Subjects -> BIOLOGY (Total: 3397 journals)
    - BIOCHEMISTRY (264 journals)
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    - BIOLOGY (1617 journals)
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    - ZOOLOGY (146 journals)

BIOLOGY (1617 journals)            First | 1 2 3 4 5 6 7 8 | Last

Showing 801 - 1000 of 1720 Journals sorted alphabetically
IRBM     Full-text available via subscription  
IRBM News     Full-text available via subscription  
iScience     Open Access  
Islets     Full-text available via subscription   (Followers: 1)
Israel Journal of Ecology and Evolution     Full-text available via subscription   (Followers: 1)
Istituto Lombardo - Accademia di Scienze e Lettere - Incontri di Studio     Open Access  
Italian Journal of Mycology     Open Access  
ITBM-RBM     Full-text available via subscription   (Followers: 1)
ITBM-RBM News     Full-text available via subscription   (Followers: 1)
IUBMB Life     Hybrid Journal   (Followers: 6)
IUFS Journal of Biology     Open Access  
Izvestiya Atmospheric and Oceanic Physics     Hybrid Journal   (Followers: 1)
Izvestiya, Physics of the Solid Earth     Hybrid Journal   (Followers: 2)
Jahangirnagar University Journal of Biological Sciences     Open Access   (Followers: 1)
Japanese Journal of Applied Physics     Full-text available via subscription   (Followers: 6)
JCI Insight     Open Access   (Followers: 3)
JDREAM : Journal of interDisciplinary REsearch Applied to Medicine     Open Access  
JETP Letters     Hybrid Journal   (Followers: 3)
Jornal Interdisciplinar de Biociências     Open Access  
Journal Biastatistics : Biomedics, Industry & Business And Social Statistics     Open Access  
Journal of Bacteriology & Parasitology     Open Access   (Followers: 5)
Journal of Bioanalysis & Biomedicine     Open Access   (Followers: 1)
Journal of Bioequivalence & Bioavailability     Open Access  
Journal of Bioremediation & Biodegradation     Open Access   (Followers: 4)
Journal of Computer Science & Systems Biology     Open Access   (Followers: 5)
Journal of Proteomics & Bioinformatics     Open Access   (Followers: 10)
Journal of Advanced Laboratory Research in Biology     Open Access   (Followers: 1)
Journal of Advances in Biology     Open Access   (Followers: 5)
Journal of Advances in Biology & Biotechnology     Open Access  
Journal of Agricultural, Biological & Environmental Statistics     Hybrid Journal   (Followers: 11)
Journal of Amino Acids     Open Access   (Followers: 4)
Journal of Anatomy     Hybrid Journal   (Followers: 7)
Journal of AOAC International     Full-text available via subscription   (Followers: 8)
Journal of Applied Biobehavioral Research     Hybrid Journal  
Journal of Applied Bioinformatics & Computational Biology     Hybrid Journal   (Followers: 5)
Journal of Applied Biological Sciences     Open Access   (Followers: 2)
Journal of Applied Biosciences     Open Access   (Followers: 1)
Journal of Applied Ichthyology     Hybrid Journal   (Followers: 6)
Journal of Applied Life Sciences International     Open Access  
Journal of Applied Phycology     Hybrid Journal   (Followers: 10)
Journal of Applied Virology     Open Access   (Followers: 5)
Journal of Aquatic Sciences     Full-text available via subscription   (Followers: 3)
Journal of Arachnology     Full-text available via subscription  
Journal of Asia-Pacific Biodiversity     Open Access  
Journal of Astrobiology & Outreach     Open Access   (Followers: 3)
Journal of Avian Biology     Hybrid Journal   (Followers: 24)
Journal of Basic Microbiology     Hybrid Journal   (Followers: 3)
Journal of Bio-Science     Open Access   (Followers: 3)
Journal of Biobased Materials and Bioenergy     Full-text available via subscription  
Journal of Biodiversity Management & Forestry     Hybrid Journal   (Followers: 6)
Journal of Bioenergetics and Biomembranes     Hybrid Journal   (Followers: 1)
Journal of Biogeography     Hybrid Journal   (Followers: 45)
Journal of Bioinformatics and Computational Biology     Hybrid Journal   (Followers: 18)
Journal of Bioinformatics and Intelligent Control     Full-text available via subscription   (Followers: 2)
Journal of Bioinformatics and Sequence Analysis     Open Access   (Followers: 1)
Journal of Biological Control     Hybrid Journal   (Followers: 2)
Journal of Biological Dynamics     Open Access   (Followers: 1)
Journal of Biological Education     Hybrid Journal   (Followers: 2)
Journal of Biological Engineering     Open Access   (Followers: 3)
Journal of Biological Methods     Open Access  
Journal of Biological Physics     Hybrid Journal   (Followers: 1)
Journal of Biological Research - Thessaloniki     Open Access  
Journal of Biological Sciences     Open Access   (Followers: 5)
Journal of Biological Systems     Hybrid Journal   (Followers: 2)
Journal of Biology and Life Science     Open Access   (Followers: 2)
Journal of Biology, Agriculture and Healthcare     Open Access   (Followers: 11)
Journal of Biomechanics     Hybrid Journal   (Followers: 41)
Journal of Biomedical Education     Open Access   (Followers: 2)
Journal of Biomedical Informatics     Partially Free   (Followers: 16)
Journal of Biomedical Informatics : X     Open Access  
Journal of Biomedical Materials Research Part A     Hybrid Journal   (Followers: 3)
Journal of Biomedical Materials Research Part B : Applied Biomaterials     Hybrid Journal   (Followers: 2)
Journal of Biomedical Nanotechnology     Full-text available via subscription   (Followers: 3)
Journal of Biomedical Physics and Engineering     Open Access  
Journal of Biomedical Science and Engineering     Open Access   (Followers: 2)
Journal of Bionic Engineering     Hybrid Journal  
Journal of Bioresource Management     Open Access  
Journal of Biorheology     Hybrid Journal  
Journal of Biosafety and Biosecurity     Open Access  
Journal of Bioscience and Bioengineering     Full-text available via subscription   (Followers: 34)
Journal of Biosciences and Medicines     Open Access   (Followers: 3)
Journal of Biosocial Science     Hybrid Journal   (Followers: 5)
Journal of Bryology     Hybrid Journal   (Followers: 7)
Journal of Cell Biology     Full-text available via subscription   (Followers: 48)
Journal of Cell Communication and Signaling     Hybrid Journal  
Journal of Cell Death     Open Access   (Followers: 2)
Journal of Cell Science     Full-text available via subscription   (Followers: 18)
Journal of Cellular Biochemistry     Hybrid Journal   (Followers: 4)
Journal of Cellular Physiology     Hybrid Journal   (Followers: 7)
Journal of Cerebral Blood Flow & Metabolism     Hybrid Journal   (Followers: 2)
Journal of Chromatography B     Hybrid Journal   (Followers: 34)
Journal of Clinical Bioinformatics     Open Access   (Followers: 5)
Journal of Clinical Toxicology     Open Access   (Followers: 6)
Journal of Communications Technology and Electronics     Hybrid Journal   (Followers: 2)
Journal of Contemporary Physics (Armenian Academy of Sciences)     Hybrid Journal   (Followers: 10)
Journal of Crustacean Biology     Hybrid Journal   (Followers: 2)
Journal of Developmental Biology     Open Access   (Followers: 2)
Journal of Ecology and The Natural Environment     Open Access   (Followers: 4)
Journal of Education, Health and Sport     Open Access   (Followers: 4)
Journal of Electrical Bioimpedance     Open Access   (Followers: 2)
Journal of Electromyography and Kinesiology     Hybrid Journal   (Followers: 5)
Journal of Environment and Ecology     Open Access   (Followers: 10)
Journal of Environment and Sociobiology     Hybrid Journal  
Journal of Environmental Analysis and Progress     Open Access  
Journal of Environmental Radioactivity     Hybrid Journal   (Followers: 3)
Journal of Environmental Science and Natural Resources     Open Access   (Followers: 4)
Journal of Ethnobiology     Full-text available via subscription   (Followers: 4)
Journal of Ethnobiology and Ethnomedicine     Open Access  
Journal of Ethology     Hybrid Journal   (Followers: 3)
Journal of Evolutionary Biology     Hybrid Journal   (Followers: 26)
Journal of Evolutionary Biology Research     Open Access  
Journal of Experimental and Clinical Anatomy     Open Access   (Followers: 2)
Journal of Experimental Life Science     Open Access  
Journal of Experimental Marine Biology and Ecology     Hybrid Journal   (Followers: 40)
Journal of Fish Biology     Hybrid Journal   (Followers: 36)
Journal of Functional Biomaterials     Open Access   (Followers: 3)
Journal of Fungi     Open Access   (Followers: 3)
Journal of Genomics     Open Access   (Followers: 1)
Journal of Great Lakes Research     Hybrid Journal   (Followers: 7)
Journal of Green Science and Technology     Full-text available via subscription   (Followers: 2)
Journal of Health and Biological Sciences     Open Access   (Followers: 1)
Journal of Heredity     Hybrid Journal   (Followers: 3)
Journal of Huazhong University of Science and Technology [Medical Sciences]     Hybrid Journal  
Journal of Human Evolution     Hybrid Journal   (Followers: 18)
Journal of Hymenoptera Research     Open Access   (Followers: 3)
Journal of Ichthyology     Hybrid Journal   (Followers: 3)
Journal of Insect Behavior     Hybrid Journal   (Followers: 7)
Journal of Insect Biodiversity     Open Access   (Followers: 4)
Journal of Insect Conservation     Hybrid Journal   (Followers: 10)
Journal of Institute of Science and Technology     Open Access  
Journal of Integrated OMICS     Open Access  
Journal of Integrated Pest Management     Open Access   (Followers: 3)
Journal of Integrative Environmental Sciences     Hybrid Journal   (Followers: 4)
Journal of Intelligent Transportation Systems: Technology, Planning, and Operations     Hybrid Journal   (Followers: 4)
Journal of Invertebrate Pathology     Hybrid Journal   (Followers: 3)
Journal of Landscape Ecology     Open Access   (Followers: 18)
Journal of Law and the Biosciences     Open Access   (Followers: 4)
Journal of Leukocyte Biology     Open Access   (Followers: 2)
Journal of Life and Earth Science     Open Access  
Journal of Life Sciences Research     Open Access  
Journal of Lipid Research     Full-text available via subscription   (Followers: 6)
Journal of Lipids     Open Access  
Journal of Luminescence     Hybrid Journal   (Followers: 4)
Journal of Mammalian Evolution     Hybrid Journal   (Followers: 7)
Journal of Mammalian Ova Research     Full-text available via subscription  
Journal of Mammalogy     Full-text available via subscription   (Followers: 13)
Journal of Mammary Gland Biology and Neoplasia     Hybrid Journal   (Followers: 1)
Journal of Marine and Aquatic Sciences     Open Access   (Followers: 1)
Journal of Marine Sciences     Open Access   (Followers: 16)
Journal of Mathematical Biology     Hybrid Journal   (Followers: 9)
Journal of Mechanics in Medicine and Biology     Hybrid Journal  
Journal of Medical Primatology     Hybrid Journal   (Followers: 1)
Journal of Medical Toxicology     Hybrid Journal   (Followers: 6)
Journal of Medicinal Botany     Open Access  
Journal of Medicine and Philosophy     Hybrid Journal   (Followers: 8)
Journal of Melittology     Open Access   (Followers: 1)
Journal of Membrane Biology     Hybrid Journal   (Followers: 1)
Journal of Membrane Computing     Hybrid Journal  
Journal of Membrane Science     Hybrid Journal   (Followers: 25)
Journal of Molecular Biology     Hybrid Journal   (Followers: 45)
Journal of Molecular Biology Research     Open Access   (Followers: 3)
Journal of Molecular Catalysis B: Enzymatic     Hybrid Journal   (Followers: 1)
Journal of Molecular Cell Biology     Hybrid Journal   (Followers: 15)
Journal of Molecular Evolution     Hybrid Journal   (Followers: 6)
Journal of Molecular Signaling     Open Access  
Journal of Molecular Structure     Hybrid Journal   (Followers: 7)
Journal of Molluscan Studies     Hybrid Journal   (Followers: 1)
Journal of Muscle Research and Cell Motility     Hybrid Journal   (Followers: 1)
Journal of Nanoparticle Research     Hybrid Journal   (Followers: 3)
Journal of Nanoparticles     Open Access   (Followers: 3)
Journal of Natural History     Hybrid Journal   (Followers: 10)
Journal of Natural Products     Hybrid Journal   (Followers: 19)
Journal of Natural Science, Biology and Medicine     Open Access   (Followers: 3)
Journal of Natural Sciences and Mathematics Research     Open Access  
Journal of Natural Sciences Research     Open Access   (Followers: 4)
Journal of Negative Results in BioMedicine     Open Access  
Journal of Nematology     Open Access   (Followers: 1)
Journal of Neuroscience and Behavioral Health     Open Access   (Followers: 1)
Journal of New Results in Science     Open Access  
Journal of New Seeds     Hybrid Journal  
Journal of Nucleic Acids     Open Access   (Followers: 1)
Journal of Parasitology     Full-text available via subscription   (Followers: 13)
Journal of Parasitology and Vector Biology     Open Access   (Followers: 2)
Journal of Pharmacological and Toxicological Methods     Hybrid Journal   (Followers: 7)
Journal of Phycology     Hybrid Journal   (Followers: 6)
Journal of Physics D : Applied Physics     Hybrid Journal   (Followers: 13)
Journal of Physics: Condensed Matter     Hybrid Journal   (Followers: 6)
Journal of Physics: Conference Series     Open Access   (Followers: 2)
Journal of Phytopathology     Hybrid Journal   (Followers: 2)
Journal of Plankton Research     Hybrid Journal   (Followers: 2)
Journal of Plant Ecology     Hybrid Journal   (Followers: 20)
Journal of Plant Pathology     Hybrid Journal  
Journal of Plasma Physics     Hybrid Journal   (Followers: 22)
Journal of Pollination Ecology     Open Access  
Journal of Porphyrins and Phthalocyanines     Hybrid Journal   (Followers: 2)
Journal of Progressive Research in Biology     Open Access   (Followers: 1)
Journal of Proteome Research     Hybrid Journal   (Followers: 12)
Journal of Proteomics     Hybrid Journal   (Followers: 10)
Journal of Purdue Undergraduate Research     Open Access   (Followers: 1)
Journal of Radiation Research and Applied Sciences     Open Access   (Followers: 2)

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Similar Journals
Journal Cover
Journal of Biomechanics
Journal Prestige (SJR): 1.147
Citation Impact (citeScore): 3
Number of Followers: 41  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0021-9290
Published by Elsevier Homepage  [3161 journals]
  • Hemodynamic Effects of Pulsatile Unloading of Left Ventricular Assist
           Devices (LVAD) on Intraventricular Flow and Ventricular Stress
    • Abstract: Publication date: Available online 15 January 2020Source: Journal of BiomechanicsAuthor(s): Kaiyun Gu, Zhiyuan Guan, Yu Chang, Bin Gao, Yunpeng Ling, Zhiming Song, Feng WanAbstractThe role of pulsatile unloading in hemodynamic changes in intraventricular flow and ventricular wall stress remains unknown. In this study, a finite element model of the left ventricle (LV) is proposed to calculate the mechanical response. The constitutive model of the LV is composed of a quasi-incompressible transversely isotropic model and an active contraction of the myocardium model. Pulsatile unloading is provided by the left ventricular assist device (LVAD), which is implanted between the aortic root and aortic arch. Support models (constant speed and co-pulse) were utilized to study the effect of pulsatile unloading on intraventricular flow and ventricular stress. The result indicates that the formation time of the vortex increases under pulsatile unloading. The area rate of high time-averaged wall shear stress (TAWSS) increased after pulsatile unloading. The area of the high oscillatory shear index (OSI) region (OSI> 0.375) was calculated for heart failure, constant speed, and co-pulse (9.9 cm2, 9.6 cm2, and 9.2 cm2, respectively). The maximum value of the stress that reflects the level of stretch declined after pulsatile unloading (66.4 kPa, 30.9 kPa, and 21.3 kPa, respectively). Besides, pulsatile unloading impacts the maximum value of thickness at the ventricular wall (-0.75 mm, -1 mm, and -1.25 mm, respectively). The change ratios of the thickness are 10%, 14%, and 17%, respectively. In conclusion, pulsatile unloading contributes to the distribution of intraventricular flow and the formation time of the vortex. Co-pulse support significantly reduces the maximum value of the ventricular wall stress and the area of high stress on the ventricular wall.
       
  • Relationship between shear modulus and passive tension of the posterior
           shoulder capsule using ultrasound shear wave elastography: A cadaveric
           study
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Naoya Iida, Keigo Taniguchi, Kota Watanabe, Hiroki Miyamoto, Tatsuya Taniguchi, Mineko Fujimiya, Masaki KatayoseAbstractAlthough shear wave elastography (SWE) has been used to indirectly measure passive tension in muscle tissues, it is unknown whether SWE can adequately evaluate passive tension in capsule tissues. This study investigated the relationship between the shear modulus and passive tension in the posterior shoulder capsule using SWE. Ten posterior middle and ten posterior inferior shoulder capsules were dissected from ten fresh-frozen cadavers; humeral head–capsule–glenoid specimens were created from each capsule. The humeral head and glenoid were immobilized with clamps in a custom-built device. Loads (0–400 g, in 25-g increments) were applied to each capsule via a pulley system; elasticity was simultaneously measured using SWE. The elasticity-load relationship of each tested capsule was analyzed by fitting a least-squares regression line to the data. Elasticity change due to creep or hysteresis effects was evaluated by comparing the elastic modulus for a 100-g load during and after the stepwise application of the loads. The observed relationship between the shear modulus and passive capsule tension was highly linear for all twenty tested capsules (p 
       
  • Validation of a low-cost inertial motion capture system for whole-body
           motion analysis
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): X. Robert-Lachaine, H. Mecheri, A. Muller, C. Larue, A. PlamondonAbstractWhile some low-cost inertial motion capture (IMC) systems are now commercially available, generally, they have not been evaluated against gold standard optical motion capture (OMC). The objective was to validate the low-cost Neuron IMC system with OMC. Whole-body kinematics were recorded on five healthy subjects during manual handling of boxes for about 32 min while wearing 17 magnetic and inertial measurement units with Optotrak clusters serving as a reference. The kinematical model was calibrated anatomically for OMC and with poses for IMC. Local coordinate systems were aligned with angular velocities to dissociate differences due to technology or kinematical model. Descriptive statistics including the root mean square error (RMSE), coefficient of multiple correlation (CMC) and limits of agreement (LoA) were applied to the joint angle curves. The average technological error yielded 5.8° and 4.9° for RMSE, 0.87 and 0.96 for CMC and 0.4 ± 8.6° and −0.3 ± 6.0° for LoA about the frontal and transverse axes respectively, whereas the longitudinal axis yielded 10.5° for RMSE, 0.78 for CMC and 3.3 ± 13.1° for LoA. Differences due to technology and to the model contributed similarly to the total difference between IMC and OMC. For many joints and axes, RMSE stayed under 5°, CMC over 0.9 and LoA under 10°, especially for the transverse axis and lower limb. The Neuron low-cost IMC system showed potential for tracking complex human movements of long duration in a normal laboratory environment with a certain error level that may be suitable for many applications involving large IMC distribution.
       
  • Characterizing the shoe-rung friction requirements during ladder climbing
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Ellen R. Martin, Erika M. Pliner, Kurt E. BeschornerAbstractLadder slip and falls cause negative financial and health impacts due to their severity and frequency. However, frictional requirements of climbing, which presumably influence slip risk, are unknown. The purpose of this study was to quantify frictional requirements during climbing at different ladder angles. The required coefficient of friction (RCOF) was calculated during ladder climbing and assessed for three ladder angles (75.5°, 82.8°, and 90°). Data was collected from 10 participants at each angle. Kinetic data and kinematic data of the climber’s shoe was collected and used to map friction and normal forces to the shoe. These forces were then used to calculate the RCOF. The RCOF and friction force at 90° was higher than at lower angles (75.5° and 82.8°). RCOF was correlated with shoe angle and body angle supporting both the relevance of shoe orientation and body position to slip risk. This study suggests that frictional requirements of ladder climbing are dependent on ladder angle, shoe orientation, and body angle.
       
  • Biomechanists can revolutionize the STEM pipeline by engaging youth
           athletes in sports-science based STEM outreach
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): John F DrazanAbstractIncreasing diversity in the STEM (Science, Technology, Engineering, and Math) fields has become imperative to ensure equitable access to economic opportunity and to provide the technologically adept workforce of the future. The present STEM pipeline preferentially engages youth who are, not only aware of and interested in STEM, but also, can see themselves on a path to a STEM career. The present pipeline fails to capture youth for whom STEM remains remote and outside their current experience. Interest in sports casts a wider net and includes populations currently underrepresented in the STEM pipeline and in STEM careers. To engage these young people in STEM, it is necessary to incorporate STEM into activities they enjoy and already participate in, such as sports. Sports engage millions of youth who are intrinsically motivated to grow and improve as athletes. Biomechanical experiments and activities can build a bridge between young people’s interest in sport activities to awareness and interest in STEM. This connection between science and sports is reinforced by the growing use of sports-science as a tool for elite athletic performance at the highest levels. The potential of sports-science to provide diverse youth with access to the STEM Pipeline is extraordinarily promising. Biomechanics researchers are uniquely positioned to deliver on the promise of sport-science based STEM outreach due to the applicability of biomechanical analysis to sports-science analysis. Historically, and not without resistance and great effort, participation in sports has broken barriers of cultural and racial discrimination within broader society. Through sports-science infused STEM outreach, biomechanists have potential to jumpstart the same process within the STEM career fields.
       
  • Characterizing healthy knee symmetry using the finite helical axis and
           muscle power during open and closed chain tasks
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Emily L. Bishop, Gregor Kuntze, Janet L. RonskyAbstractUnderstanding healthy joint movement and muscle control, and injurious alterations, is important to determine musculoskeletal contributions to post-injury joint instabilities or altered dynamic joint function. The contralateral limb is often used as a point of reference to determine the effects of knee joint injury. However, it is currently difficult to interpret within subject variability between limbs as this is not well established in the healthy population. There is a continuing need to characterize healthy knee joint mechanics and neuromuscular control to determine the degree of symmetry within healthy individuals. The current study quantified limb symmetry in healthy individuals using the finite helical axis with a unique reference position (rFHA) and electromyography (EMG) approaches, for a closed-chain single leg squat (SLS) and an open-chain seated leg swing. Muscle power and FHA translation, orientation and dispersion were similar between limbs. However, the FHA was located significantly more anterior in the dominant limb relative to the contralateral during both tasks. These between-limb differences in FHA location could be attributed to differences in joint geometry and strength between limbs. This finding provides evidence that healthy knees have asymmetries which have implications for selection of control limbs in studies comparing conditions within and between individuals. Differences identified in dynamic joint function between tasks suggest that the SLS is useful for revealing joint asymmetries due to altered muscular control strategies, while the swing task is expected to highlight asymmetries in joint motion due to altered knee structures following injury.
       
  • Protective arm movements are modulated with fall height
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): James Borrelli, Robert Creath, Mark W. RogersAbstractProtective arm reactions were evoked in 14 younger adults to determine the effect of fall height on protective arm reaction biomechanics. Participants were supported in a forward-leaning position on top of an inverted pendulum that isolated arm reaction by preventing any fall arresting contribution that may come from the ankle, knees, or hip. At an unpredictable time, the pendulum was released requiring participants to rapidly orient their arms to protect the head and body. Vertical ground reaction force (vGRF), arm kinematics, and electromyographic (EMG) measures of the biceps and triceps were compared at four initial lean angles. The time following perturbation onset and prior to impact consisted of two phases: rapid extension of the elbows and co-activation of the biceps and triceps in preparation for impact. The rapid orientation phase was modulated with fall height while the co-activation of the biceps and triceps in preparation for landing was minimally affected. Larger lean angles resulted in increased vGRF, increased elbow extension at impact, decreased elbow angular extension velocity at impact, and increased neck velocity at impact while hand velocity at impact was not significantly affected. The neuromuscular control strategy appears to optimize elbow extension angle/angular velocity prior to co-activation of the biceps and triceps that occurs about 100 ms prior to impact. Future work should investigate how the neuromuscular control strategy handles delayed deployment of protective arm reactions.
       
  • Intravaginal pressure profile of continent and incontinent women
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Licia P. Cacciari, Amanda C. Amorim, Anice C. Pássaro, Chantal Dumoulin, Isabel C.N. SaccoAbstractA well-functioning pelvic floor muscle plays an important role in maintaining urinary continence. The aim of this study was to describe and compare the intravaginal pressure profile using a multisensor device along the vaginal length in women with and without urinary incontinence (UI), while performing pelvic floor muscle tasks. Fifty-four adult pre-menopausal women (31 continent and 23 incontinent) participated in this cross-sectional observational cohort study. The intravaginal pressure profile was assessed at rest, during maximum and sustained pelvic floor muscle contractions, using the Pliance® multisensor device. Between-group comparisons were performed considering the overall pressure and the pressure profile of 10-subregions along the vaginal length. In the overall pressure assessment, women with UI presented lower pressures at rest, similar pressures during maximum contraction and lower capacity to maintain pressure during sustained contraction compared to those in the continent group. The pressure profile assessment showed between-group differences that were consistent throughout tasks, with the incontinent group presenting lower pressures than the continent group, specifically in the mid-vaginal length, around 3–4 cm from the vaginal opening. We observed consistent deficits in pressure generation in incontinent compared to continent women, precisely in the region of the pelvic floor muscles. With this protocol and novel instrument, we obtained a reliable and consistent intravaginal pressure profile of continent and incontinent women. This approach could assist clinicians in the assessment of pelvic floor muscle function and foster a better understanding of the urinary incontinence mechanism.
       
  • Does variability in motor output at individual joints predict stride time
           variability in gait' Influences of age, sex, and plane of motion
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Christopher A. Bailey, Micaela Porta, Giuseppina Pilloni, Federico Arippa, Julie N. Côté, Massimiliano PauAbstractOld age is associated with variability in gait motor output, particularly in females, and is linked to fall risk. However, little is known about how older age and sex affect variability in the outputs of individual joints, and how these variabilities contribute to the collective gait output. Healthy adults aged 18–99 years (N = 102, 57 females) completed six trials of straight walking at self-selected speed. Stride time variability (coefficient of variation) and variabilities of lower limb tridimensional joint angles (standard deviations: SD) were calculated. Age * Sex (A * S) mixed models were conducted on all measures and year-by-year rates of change were subsequently estimated. Correlations and stepwise linear regression analyses were computed between joint angular variabilities and stride time variability. Each year of age was associated with 0.022% higher stride time variability (A: p = .002), 0.07° lower variability in peak ankle dorsiflexion (A: p = .004), 0.002–0.098° higher variability in mean ankle inversion/eversion, mean pelvic obliquity, and pelvic rotation range of motion (A: p 
       
  • Temporal kinematic differences throughout single and double-leg forward
           landings
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Jennifer A. Hogg, Jos Vanrenterghem, Terry Ackerman, Anh-Dung Nguyen, Scott E. Ross, Randy J. Schmitz, Sandra J. ShultzAbstractScreening methods for anterior cruciate ligament (ACL) injuries often involve double-leg landings, though the majority of ACL injuries occur during single-leg landings. Differences in kinematic temporal characteristics between single-leg and double-leg landings are poorly understood. The purpose of this study was to examine discrete and temporal kinematics associated with functional valgus collapse during single-leg and double-leg landings (LANDSL and LANDDL). Three-dimensional kinematics were obtained during the landing phases of LANDSL and LANDDL in ninety participants (45 females: 20.1 ± 1.7 yr, 165.2 ± 7.6 cm, 68.6 ± 13.1 kg; 45 males: 20.7 ± 2.0 yr, 177.7 ± 8.5 cm, 82.8 ± 16.3 kg). Peak joint angles and time series curves for frontal and transverse plane hip and knee kinematics were analyzed with an RMANOVA (discrete variables) and Statistical Parametric Mapping (SPM) paired t-tests (time series). LANDSL elicited greater knee abduction than LANDDL from 0 to 35% (0–73 ms) but greater knee adduction from 54 to 100% (112–207 ms). Peak knee abduction was 2.0° greater during LANDDL than during LANDSL (p 
       
  • The biomechanics of concussive helmet-to-ground impacts in the National
           Football league
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Richard Kent, Jason Forman, Ann M. Bailey, James Funk, Chris Sherwood, Jeff Crandall, Kristy B. Arbogast, Barry S. MyersAbstractThis paper presents a detailed characterization of helmet-to-ground impacts in the National Football League. Video analysis was performed for 16 head-to-ground impacts that caused concussions. Average resultant closing velocity was 8.3 m/s at an angle nearly 45° to the surface. Preimpact rotational velocity of the helmet ranged from negligible to as high as 54.1 rad/s. Helmet impacts were concentrated on the posterior and lateral aspects.To study the interaction in greater detail, a helmeted anthropomorphic test device (ATD) was launched over a football field and fell to the ground in various impact conditions. Substantial decoupling between the helmet and the head was observed, such that the head rebounded within the helmet and underwent changes in linear and rotational motion greater than those of the helmet. Vertical helmet rebound was also observed; the helmet underwent a change in vertical velocity on average 24% greater than the vertical component of its closing velocity. Frictional interaction between the helmet and the ground surface caused the helmet to undergo an average horizontal change in velocity of 57% of the horizontal component of its closing velocity. Finally, the duration of a helmet-to-ground impact was generally in the range of 15 – 30 ms, suggesting that the impact surface provides little ride-down. Lengthening this duration could be beneficial both by reducing the peak linear and rotational acceleration and by shifting the impact toward a time regime where brain strain is related to rotational acceleration rather than rotational velocity.
       
  • Effects of segment masses and cut-off frequencies on the estimation of
           vertical ground reaction forces in running
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Dimitrios-Sokratis Komaris, Eduardo Perez-Valero, Luke Jordan, John Barton, Liam Hennessy, Brendan O'Flynn, Salvatore TedescoAbstractThe purpose of this study is to examine the effect of the body’s mass distribution to segments and the filtering of kinematic data on the estimation of vertical ground reaction forces from positional data. A public dataset of raw running biomechanics was used for the purposes of the analysis, containing recordings of twenty-eight competitive or elite athletes running on an instrumented treadmill at three different speeds. A grid-search on half of the trials was employed to seek the values of the parameters that optimise the approximation of biomechanical loads. Two-way ANOVAs were then conducted to examine the significance of the parameterised factors in the modelled waveforms. The reserved recordings were used to validate the predictive accuracy of the model. The cut-off filtering frequencies of the pelvis and thigh markers were correlated to running speed and heel-strike patterns, respectively. Optimal segment masses were in agreement with standardised literature reported values. Root mean square errors for slow running (2.5 m/s) were on average equal to 0.1 (body weight normalized). Errors increased with running speeds to 0.13 and 0.18 for 3.5 m/s and 4.5 m/s, respectively. This study accurately estimated vertical ground reaction forces for slow-paced running by only considering the kinematics of the pelvis and thighs. Future studies should consider configuring the filtering of kinematic inputs based on the location of markers and type of running.
       
  • Development of a two-dimensional dynamic model of the foot-ankle system
           exposed to vibration
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): D. Chadefaux, K. Goggins, C. Cazzaniga, P. Marzaroli, S. Marelli, R. Katz, T. Eger, M. TarabiniAbstractWorkers in mining, mills, construction and some types of manufacturing are exposed to vibration that enters the body through the feet. Exposure to foot-transmitted vibration (FTV) is associated with an increased risk of developing vibration-induced white foot (VIWFt). VIWFt is a vascular and neurological condition of the lower limb, leading to blanching in the toes and numbness and tingling in the feet, which can be disabling for the worker. This paper presents a two-dimensional dynamic model describing the response of the foot-ankle system to vibration using four segments and eight Kelvin-Voigt models. The parameters of the model have been obtained by minimizing the quadratic reconstruction error between the experimental and numerical curves of the transmissibility and the apparent mass of participants standing in a neutral position. The average transmissibility at five locations on the foot has been optimized by minimizing the difference between experimental data and the model prediction between 10 and 100 Hz. The same procedure has been repeated to fit the apparent mass measured at the driving point in a frequency range between 2 and 20 Hz. Monte Carlo simulations were used to assess how the variability of the mass, stiffness and damping matrices affect the overall data dispersion. Results showed that the 7°-of-freedom model correctly described the transmissibility: the average transmissibility modulus error was 0.1. The error increased when fitting the transmissibility and apparent mass curves: the average modulus error was 0.3. However, the obtained values were reasonable with respect to the average inter-participant variability experimentally estimated at 0.52 for the modulus. Study results can contribute to the development of materials and equipment to attenuate FTV and, consequently, lower the risk of developing VIWFt.
       
  • Deformable link segment analysis for prosthetic foot-ankle components:
           Kinematics
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Stacey R. Zhao, J. Timothy Bryant, Qingguo LiAbstractApproaches in the literature for estimating prosthetic foot-ankle power typically require calculating the segment deformation velocity. This, in turn, necessitates approximating the segment angular velocity. Methods can be distinguished by the way in which a segment is defined and the assumptions used for estimating the segment angular velocity. However, isolating foot-ankle performance from overall prosthetic system performance is limited by uncertainties in the definition of angular velocity of a deformable segment. A deformable link segment (DLS) analysis is proposed that provides a means for estimating deformation velocity of a deformable segment without first approximating the angular velocity: the deformation velocity and angular velocity are solved simultaneously at each instant during the stance phase of gait. DLS analysis was compared to two approaches in the literature: the distal foot (DF) model and the unified deformable (UD) segment model during over-ground walking for three trans-tibial prosthesis users. DLS and UD segment estimates of deformation velocity were comparable when applied to the UD segment. Furthermore, DLS analysis enables modelling of deformable prosthetic foot-ankle components separately from other prosthetic componentry. The method is proposed as a rigorous approach to estimating angular velocity and deformation velocity of passive prosthetic foot-ankle components for subsequent calculation of deformation power and energy performance of these devices.
       
  • A feasibility study of deep learning for predicting hemodynamics of human
           thoracic aorta
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Liang Liang, Wenbin Mao, Wei SunAbstractNumerical analysis methods including finite element analysis (FEA), computational fluid dynamics (CFD), and fluid–structure interaction (FSI) analysis have been used to study the biomechanics of human tissues and organs, as well as tissue-medical device interactions, and treatment strategies. However, for patient-specific computational analysis, complex procedures are usually required to set-up the models, and long computing time is needed to perform the simulation, preventing fast feedback to clinicians in time-sensitive clinical applications. In this study, by using machine learning techniques, we developed deep neural networks (DNNs) to directly estimate the steady-state distributions of pressure and flow velocity inside the thoracic aorta. After training on hemodynamic data from CFD simulations, the DNNs take as input a shape of the aorta and directly output the hemodynamic distributions in one second. The trained DNNs are capable of predicting the velocity magnitude field with an average error of 1.9608% and the pressure field with an average error of 1.4269%. This study demonstrates the feasibility and great potential of using DNNs as a fast and accurate surrogate model for hemodynamic analysis of large blood vessels.
       
  • Implications of rectal preconditioning for interpretation of sensory-motor
           data
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Jingbo Zhao, Tine Gregersen, Janne Fassov, Klaus Krogh, Hans GregersenAbstractTesting of biomechanical properties of intestine requires the tissue to be preconditioned by applying cyclic loading to obtain repeatable mechanical data. However, little is known about the mechanosensory properties during intestinal preconditioning. We aimed to study the relationship between mechanical preconditioning of the human rectum and sensory response. Three fast rectal bag distensions to the pain threshold were done in seven healthy females. A visual analog scale (VAS) was used for sensory assessment. At each distension, we determined (1) time, bag cross-sectional area (CSA), radius (r), r/r0, pressure and tension to reach VAS = 1, 3 and 5 (pain threshold); (2) the same parameters at induced contraction start; (3) CSA where the pressure started to increase (CSAP>baseline) and (4) the number of contractions. The time, CSA, r/r0 and tension to reach VAS = 1 and VAS = 3 increased from distension 1 to 3 (4.9  0.007), primarily due to difference between the first and second distension. For VAS = 5, r/r0 was smaller in distension 3 than distension 1 (P  0.5). Compared with distension 1, CSA, r/r0 and tension at contraction start, and CSAP>baseline were bigger in distensions 2 and 3 (5.5  0.009). The pressure to reach the VAS levels, the contraction numbers and pressure at contraction start did not differ among distensions (P > 0.6). During mechanical preconditioning, CSA, tension and deformation increased at sub-pain levels, reflecting sensory adaptation. The data point to acute remodeling of a strain-dependent mechanism in the rectal wall.
       
  • Foot flexibility confounds the assessment of triceps surae extensibility
           in children with spastic paresis during typical physical examinations
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Guido Weide, Peter A. Huijing, Jules G. Becher, Richard T. Jaspers, Jaap HarlaarAbstractAccurate assessment of the talo-crural (ankle) joint angle at physical examination is important for assessing extensibility of m. triceps surae (TS) in children with spastic cerebral paresis (SCP). The main aim of this study was to quantify foot flexibility during standardized measurements of TS muscle-tendon complex extensibility (i.e. based on foot-sole rotation) in SCP children, and typical developed (TD) ones. Additionally, we aim to define a method that minimizes the confounding effects of foot flexibility on estimates of talo-crural joint angles and TS extensibility.Children, aged 6–13 years, with SCP (GMFCS I-III, n = 13) and TD children (n = 14) participated in this study. Externally applied −1 Nm, 0 Nm, 1 Nm and 4 Nm dorsal flexion foot plate moments were imposed. Resulting TS origin-insertion lengths, foot sole (φFoSo) rotations, and changes in talo-crural joint angle (φTaCr) were measured. Foot flexibility was quantified as Δ(φTaCr -φFoSo) between the 0 Nm and 4 Nm dorsal flexion conditions.In both groups, φFoSo rotations of approximately 20° were observed between 0 Nm and 4 Nm dorsal flexion, of which about 6° (≈30%) was related to foot flexibility. Foot flexibility correlated to φFoSo (r = 0.69) but not to φTaCr (r = 0.11). For φFoSo no significant differences were found between groups at 4 Nm. However, for SCP children the mean estimate of φTaCr was 4.3° more towards plantar flexion compared to the TD group (p 
       
  • Active arm swing and asymmetric walking leads to increased variability in
           trunk kinematics in young adults
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Tarique Siragy, Cezar Mezher, Allen Hill, Julie NantelAbstractFall induced injuries are a leading cause for occupational injuries with the majority originating from challenging same-level walking surfaces. Despite current perturbation and fall prevention paradigms, occupational fall prevalence remains stable. Typically, these paradigms do not account for arm swing which has been demonstrated to affect the center of mass′ movement during walking. This study examined the effect of different arm swing on postural control during symmetric and asymmetric walking. Fifteen healthy young adults (age = 23.4 ± 2.8) walked symmetrically and asymmetrically with three arm motions (normal, held, and active) on a split-belt treadmill CAREN Extended-System (Motek Medical, Amsterdam, NL). Mean, standard deviation and maximal values of trunk linear and angular velocity, and whole-body angular momentum were calculated in all three axes; additionally, step length, time and width mean and Coefficient of Variation, Margin of Stability and Harmonic Ratios were calculated. Compared to normal and held conditions, active arm increased trunk linear and angular velocity standard deviation, max velocity values, mean step length and time, as well as the Coefficient of Variation for step length, time, and width. Furthermore, whole-body angular momentum increased as a function of arm swing amplitude. Active arm swing further reduced Harmonic Ratios in the mediolateral and anteroposterior directions. Asymmetric walking increased average step time, and width as well as increased the Coefficient of Variation for step length and time but reduced left average step length and step width Coefficient of Variation. Further, asymmetric walking increased mediolateral Margin of Stability and reduced anteroposterior and mediolateral Harmonic Ratios. Finally, results demonstrated that actively increasing arm swing increases trunk linear and angular velocity variability in healthy young adults during symmetric and asymmetric treadmill walking. Findings may be due to active arm swing and asymmetric walking causing a disproportional contribution to trunk and center of mass movement causing participants to modify their base of support to maintain stability.
       
  • Thickness, cross-sectional area, and stiffness of intrinsic foot muscles
           affect performance in single-leg stance balance tests in healthy sedentary
           young females
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Serkan Taş, Nezehat Özgül Ünlüer, Alp ÇetinAbstractThe purpose of this study was to investigate the effect of thickness, cross-sectional area and stiffness of intrinsic foot muscles on performance in single-leg stance balance tasks in healthy sedentary young females. This study included a total of 40 healthy sedentary young females between the ages of 19 and 35 years. Single-leg stance balance assessments were carried out using Biodex Balance Systems (Biodex Medical Systems, Shirley, NY, USA). Performance in the single-leg stance balance tests was assessed using the overall stability index (OSI), mediolateral stability index (MLSI) and the anteroposterior stability index (APSI). Lower scores indicated better postural stability. Stiffness, thickness and cross-sectional area measurements of the abductor hallucis (AbH), flexor digitorum brevis (FDB) and flexor hallucis brevis (FHB) muscles were performed using an ultrasonography device. Larger AbH and FHB muscles were correlated with higher OSI, APSI, and MLSI (r = 0.31–0.46, p 
       
  • A novel method for measuring asymmetry in kinematic and kinetic variables:
           The normalized symmetry index
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Robin Queen, Laura Dickerson, Shyam Ranganathan, Daniel SchmittAbstractGait and movement asymmetries are important variables for assessing locomotor mechanics in humans and other animals and as a predictor of injury risk and success of clinical interventions. The four indices used most often to assess symmetry are not well designed for different variable types, perform poorly when presented with cases of high asymmetry or when variables are of low magnitude, and are easily influenced by small variation in the signal. The purpose of the present study was to test the performance of these indices on previously unpublished data on ACL-R patients and to propose a new index to resolve some of these limitations. The performance of four currently used indices and a new index—the Normalized Symmetry Index (NSI), which is scaled to the range of variables being tested across multiple trials—were compared using force and angular data on participants who had undergone anterior cruciate ligament reconstruction and healthy controls. The NSI performed well compared to all other indices with all variables and had the additional benefit of returning values that range from 0% (full symmetry) to ±100% (full asymmetry). Therefore, the NSI can serve as a universal index for assessing asymmetry in humans, nonhuman animal models, and in a clinical context for assessing risk for injury and clinical outcomes.
       
  • ISB recommendations on the reporting of intersegmental forces and moments
           during human motion analysis
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Timothy R. Derrick, Antonie J. van den Bogert, Andrea Cereatti, Raphael Dumas, Silvia Fantozzi, Alberto LeardiniThe International Society of Biomechanics (ISB) has charged this committee with development of a standard similar in scope to the kinematic standard proposed in Wu et al. (2002) and Wu et al. (2005). Given the variety of purposes for which intersegmental forces and moments are used in biomechanical research, it is not possible to recommend a particular set of analysis standards that will be acceptable in all applications. Instead, it is the purpose of this paper to recommend a set of reporting standards that will result in an understanding of the differences between investigations and the ability to reproduce the research. The end products of this standard are (1) a critical checklist that can be used during submission of manuscripts and abstracts to insure adequate description of methods, and (2) a web based visualization tool that can be used to alter the coordinate system, normalization technique and internal/external perspective of intersegmental forces and moments during walking and running so that the shape and magnitude of the curves can be compared to one’s own data.
       
  • Maturity offset affects standing postural control in youth male soccer
           players
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Matteo Zago, Alex Patten Moorhead, Filippo Bertozzi, Chiarella Sforza, Marco Tarabini, Manuela GalliAbstractQuantifying the response of postural control in developmental athletes makes it possible to understand critical coordination and learning phases and to improve technical-physical interventions. However, the influence of maturation on postural control amongst young soccer players has neither been tested using quantitative methods, nor over a wide age range.In this study, we examined stabilometric parameters of 238 young male soccer players from 9 to 17 years old relative to maturity offset. Two 30-s tests (eyes open and eyes closed) were recorded on a baropodometric platform at 50 Hz. Participants were split into six groups according to their maturity offset, expressed as years from individual’s peak height velocity. Dependent variables were: Sway Area, Center-of-Pressure velocity, standard deviation of the antero-posterior and medio-lateral Center-of-Pressure trajectory, Romberg Quotient.Sway Area was significantly higher in players with maturity offset  0.5 years (p −0.5 years (p 
       
  • Effects of sports bra and footwear on vertebral posture during walking and
           running
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Juliane Cristina Leme, Yasmim Barbosa dos Reis, Luiza dos Santos Banks, Jefferson Rosa Cardoso, Mario Hebling Campos, Felipe Arruda MouraAbstractLittle attention has been given to factors which affects women running, such as proper footwear and breast support and their effects on spine. The objective of study was to analyse the influence of different breast support and footwear on vertebral posture during walking and running. Seventeen women (x¯ = 23.51; SD = 3.70 years) performed a treadmill walking (5 km/h) and running (7 and 10 km/h) with different footwear (barefoot, minimalist and traditional) and breast support (bare breast, everyday bra and sports bra) conditions. Spine movements were analyzed using three cameras in grayscale video mode, positioned behind the participant to register reflective markers fixed in the vertebrae. From the 3D coordinates of the trunk markers we computed, for the whole gait cycle (C) and for the average gait posture (neutral curve–NC) the maximal (M) thoracic (T) kyphosis and lateral flexion, and the maximal lumbar (L) lordosis and lateral flexion. Frontal plane: bare breast presented higher lumbar NC than the everyday bra and sports bra, higher MLC than the sports bra and lower MTC than the everyday bra and sports bra. Barefoot presented higher MTC than minimalist. Sagittal plane: bare breast presented lower MTC than the sports bra. Barefoot presented higher lumbar NC than the minimalist and traditional footwear and higher MLC than the minimalist and traditional ones. The sports bra increased curvatures in the thoracic spine that were rectified during bare breast conditions. In addition, both footwears were able to maintain the natural curvatures of the spine in the lumbar.
       
  • Characterization of polyvinyl alcohol hydrogels as tissue-engineered
           
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Mohadeseh Nazouri, Alireza Seifzadeh, Elahe MasaeliAbstractMechanical strength along with high biocompatibility and water absorbing are among main characteristics of a desirable scaffold for cartilage tissue engineering. Having these properties, polyvinyl alcohol (PVA) can be a good option for constructing cartilage tissue engineering scaffolds. In this study, PVA hydrogel was produced by freeze-thaw crosslinking method, and its mechanical properties such as viscoelastic and hyperplastic behavior, which cannot be obtained analytically, was investigated with a coupled finite element (FE)-optimization algorithm and stress relaxation experimental data. To obtain isotropic hyper-viscoelastic constitutive parameters of PVA scaffolds, the Mooney-Rivlin and Neo-Hooke strain energy functions, in which shear and bulk moduli varies with time, were applied. Results showed that predicted mechanical responses of scaffolds by the Mooney-Rivlin model better fitted stress-relaxation experiments than those obtained by Neo-Hooke one. Also, the properties obtained from the finite element model, such as the bulk and the shear moduli, showed that, after successful in vitro and in vivo experiments, PVA hydrogel may be introduced as a cartilage substitute for future tissue engineering therapies.
       
  • Changes in hip mechanics during gait modification to reduce knee abduction
           moment
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Sarah Kettlety, Bryndan Lindsey, Oladipo Eddo, Matt Prebble, Shane Caswell, Nelson CortesAbstractFirst peak knee abduction moment (KAM) has been associated with the severity and progression of knee osteoarthritis (KOA). Gait modifications, including lateral trunk lean (TL), medial knee thrust (MKT), and reduced foot progression (FP) have decreased KAM. However, their effects on the hip joint are poorly understood. Reduced hip abduction moment has been found to be predictive of KOA progression and has been hypothesized to represent a decreased demand on the hip musculature. Lack of studies investigating changes in hip mechanics as a result of gait modification limits our understanding of their cumulative benefit, therefore, we investigated the effects of TL, MKT, and FP on internal hip abduction moment as well as rate change in net joint reaction force. Using real-time visual biofeedback, five trials were completed for each modification. Each modification target range was individualized to 3–5 SD greater (TL and FP) or lesser (MKT) than the participants mean baseline value. Kinematics and kinetics at the hip and knee were calculated at first peak KAM. Trunk lean and MKT decreased hip abduction moment compared to baseline (p 
       
  • Do gait and muscle activation patterns change at middle-age during
           split-belt adaptation'
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): D. Vervoort, A.R. den Otter, T.J.W. Buurke, N. Vuillerme, T. Hortobágyi, C.J.C. LamothAbstractAdvancing age affects gait adaptability, but it is unclear if such adaptations to split-belt perturbations are already affected at middle-age. Changes in neuromuscular control, that already start at middle-age, may underlie the age-related changes in gait adaptation. Thus, we examined the effects of age on adaptations in gait and muscle activation patterns during split-belt walking in healthy young and middle-aged adults. Young (23.3 ± 3.13 years) and middle-aged adults (55.3 ± 2.91 years) walked on an instrumented split-belt treadmill. Both age groups adapted similarly by reducing asymmetry in step length and double support time. Surface EMG was recorded from eight leg muscles bilaterally. Principal Component Analysis (PCA) was applied to the EMG data of all subjects, for the fast and slow leg separately, to identify muscle activation patterns. The principal components consisted of i.e. temporal projections that were analyzed with Statistical Parametric Mapping (SPM). The functional muscle groups, identified by PCA, increased activation during early adaptation and post-adaptation, and decreased activation over time similarly in both age groups. Extra activation peaks of the plantar- and dorsiflexors suggest a role in gait modulation during split-belt walking. Both young and middle-aged adults re-established gait symmetry and showed adaptation effects in the muscle activation patterns. Since the adaptation of muscle activation patterns parallels adaptation of gait symmetry, changes in muscle activation likely underlie the changes in step parameters during split-belt adaptation. In conclusion, split-belt adaptation, in terms of gait and muscle activation patterns, is still preserved at middle-age, suggesting that age-related differences occur later in the lifespan.
       
  • Biomechanical contribution of the alar ligaments to upper cervical
           stability
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Robert Tisherman, Robert Hartman, Kharthik Hariharan, Nicholas Vaudreuil, Gwendolyn Sowa, Michael Schneider, Michael Timko, Kevin BellAbstractAcute and chronic whiplash-associated disorders pose a significant healthcare burden due to chronic pain, which is associated with upper cervical instability resulting from ligamentous injury. No standard measure exists for diagnosing alar ligament injury and imaging findings vary widely. Multiple physical examination maneuvers are used to diagnose alar ligament injury including the C2 Spinous Kick, Flexion-Rotation, and Bending-Rotation tests. The objective of the current study was to determine the mechanical contribution of the alar ligaments to upper cervical stability and quantify the biomechanical changes seen during simulated clinical examinations after alar ligament injury. Eight cadaveric C0-C3 specimens were evaluated using a robotic testing system. Range of motion and moment at the end of intact specimen replay were the primary outcomes. Clinical examinations were simulated by rotation through two axes as performed during physical examination. Intact, unilateral and bilateral alar ligament injury states were tested. Unilateral alar ligament injury led to significant increases in lateral bending (12.0 ± 7.2%, p 
       
  • A modular impact diverting mechanism for football helmets
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Daniel E. Abram, Adrian Wikarna, Farid Golnaraghi, G. Gary WangAbstractTo mitigate the injurious effect of the rotational acceleration of the brain, a modular Impact Diverting Mechanism (IDM) has been developed. The IDM can replace stickers (decals) that normally attach to the exterior of a football helmet. The IDM decals reduce friction and catch points between the covered area with the IDM on the outer shell of the helmet and the impacting surface, thereby decreasing rotational acceleration acting on the player’s head. A Riddell Speed helmet’s exterior was prepared with the IDM and outfitted to a headform equipped with linear accelerometers and gyroscopes. The helmets were tested at an impact velocity of 5.5 m/s at 15°, 30°, and 45° to the vertical: on the front, side, and back of the helmet. Results of 135 impact tests in the lab show that the IDM decal, when compared to helmets without it, reduced the rotational acceleration, rotational velocity, SI, HIC, and RIC ranging from 22% to 77%, 20% to 74%, 13% to 68%, 7% to 68%, 31% to 94%, respectively. Protection against rotational acceleration from oblique impacts is not prioritized in modern football helmets, as evident by current standard helmet testing protocols. This study demonstrates that the inclusion of the IDM decals in football helmets can help reduce the effects of rotational acceleration of the head during oblique impacts.
       
  • An optimization method for surgical reduction of hypertrophied inferior
           turbinate
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Huahui Xiong, Han Cao, Yaqi HuangAbstractSurgical reductions of the hypertrophied inferior turbinate (HIT) can improve nasal obstruction. However, there is currently a lack of personalized and objective methods to guide surgical operations, which results in the excessive or inadequate resection of HIT. In this study, we proposed an optimizing method based on homotopy deformation to determine the resected amount and shape of the tissue by matching the flow resistance in the two nasal passageways. The simulation results obtained using computational fluid dynamics showed that after such an optimization procedure, the most obstructed nasal side could have a similar air flux as the less obstructed side. A 35% and a 56% less tissue resection in the optimizing operation compared to that in the total turbinectomy could well balance the air flow between the two nasal cavities in the simulations for patients 1 and 2 with unilateral nasal obstruction respectively. Compared with the optimization operation, the total turbinectomy made a more aggressive resection of HIT, which could worsen the air conditioning capacity of the nose. A sensitivity test indicated that in the optimization operation, the most constricted region in the nasal cavity should be adequately enlarged. However, more tissue resection than is required for the optimization operation did not improve the flow in the obstructed side strikingly. Simulations of the optimization operation in both nasal cavities for a patient with bilateral nasal obstruction were also performed. The flow rate could reach the normal level and be well balanced in the two sides after such an optimization procedure.
       
  • Force interactions between Yersiniae lipopolysaccharides and monoclonal
           antibodies: An optical tweezers study
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Ilya Konyshev, Andrey Byvalov, Boris Ananchenko, Rawil Fakhrullin, Anna Danilushkina, Lyubov DudinaAbstractThis article reports the force spectroscopy investigation of interactions between lipopolysaccharides (LPSs) of two species from Yersinia genus and complementary (or heterologous) monoclonal antibodies (mAbs). We have obtained the experimental data by optical trapping on the “sensitized polystyrene microsphere – sensitized glass substrate” model system at its approach – retraction in vertical plane. We detected non-specific interactions in low-amplitude areas on histograms mainly due to physicochemical properties of abiotic surface and specific interactions in complementary pairs “antigen – antibodies” in high-amplitude areas (100–120 pN) on histograms. The developed measurement procedure can be used for detection of rupture forces in other molecular pairs.
       
  • Effect of first order chemical reactions on the dispersion coefficient
           associated with laminar flow through fibrosis affected lung
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Jyoti Kori, PratibhaAbstractIn this paper, we worked on the effective area average concentration and dispersion coefficient associated with the unsteady flow, to understand the dispersion in the fibrosis-affected lung. We assumed that the tube wall (i.e. alveolar or pulmonary capillary wall) is thicker than its normal size due to fibrosis and chemical species may go through linear first-order kinetic reactions, one is reversible phase exchange with the wall material and other is irreversible absorption into the tube wall. By considering diffusivity as a function of thickness, the dispersion can be calculated by the distribution of concentration of gas along a tube. Mathematical modeling is done by using diffusion equation; and effects of various dimensionless parameters e.g., the Damkohler number (DA), phase partitioning number (α), dimensionless absorption number (Γ), thickness and permeability of wall are observed. Numerical simulation shows that the diffusion rate through the respiratory wall is decreased significantly as the thickness of wall increases, while it increased with the increment in the porosity of wall, the concentration of species increased when the tube wall thickness increases; which cause reduction in the spread of the species; additionally, the dispersion coefficient achieves the steady-state values in a very short time when 0
       
  • The effects of upper airway tissue motion on airflow dynamics
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Yongling Zhao, Joel Raco, Agisilaos Kourmatzis, Sammy Diasinos, Hak-Kim Chan, Runyu Yang, Shaokoon ChengAbstractThe human upper airway is not only geometrically complex, but it can also deform dynamically as a result of active muscle contraction and motility during respiration. How the active transformation of the airway geometry affects airflow dynamics during respiration is not well understood despite the importance of this knowledge towards improving current understanding of particle transport and deposition. In this study, particle imaging velocimetry (PIV) measurements of the fluid dynamics are presented in a physiologically realistic human upper airway replica for (i) the undeformed case and (ii) the case where realistic soft tissue motion during breathing is emulated. Results from this study show that extrathoracic wall motion alters the flow field significantly such that the fluid dynamics is distinctly different from the undeformed airway. Distinctive flow field patterns in the physiologically realistic airway include (i) fluid recirculation at the back of the tongue and cranial to the tip of the epiglottis during mid-inspiration, (ii) horizontal and posteriorly directed flow at the back of tongue at the peak of inspiration and (iii) a more homogeneous flow across the airway downstream from the epiglottis. These findings suggest that the active deformation of the human upper airway may potentially influence particle transport and deposition at the back of the tongue and therefore, highlights the importance of considering extrathoracic wall motion in future airway flow studies.D.
       
  • Mechanical characterization of an in-body tissue-engineered autologous
           collagenous sheet for application as an aortic valve reconstruction
           material
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Takeshi Terazawa, Takayuki Kawashima, Tadashi Umeno, Tomoyuki Wada, Shigeyuki Ozaki, Shinji Miyamoto, Yasuhide NakayamaAbstractThe reconstruction of the aortic valve using glutaraldehyde-treated autologous pericardium is known as “aortic valve neo-cuspidization” (AVNeo). In-body tissue architecture (iBTA), a cell-free, in vivo tissue-engineering technology that can form autologous implantable tissues of the desired shape by subcutaneous embedding specially designed molds, was used to prepare sheet-like collagenous tissues called “Biosheets”. Cylindrical molds with several line slits arranged in an alternating (n = 30) or parallel (n = 36) pattern were subcutaneously embedded in goats (n = 12) for 2 or 3 months. The tubular tissues formed in the molds were dried and then cut in the longitudinal direction, thus obtaining Biosheets (5 × 7 cm). The success rate was 97.6% when using the alternating-pattern molds and 97.2% for the parallel molds. Thickness mapping of the Biosheets showed that their entire surface, except for the line-projection portions, was smooth without any defects. The average wall thickness could be controlled over a range of ca. 0.2–0.5 mm by changing the size of the gap (0.75–1.5 mm) in the molds. The alternating slit-patterned Biosheets were found to be almost isotropic in their mechanical properties (ultimate tensile strength, fracture strain, and Young’s modulus). Although the composition of the Biosheet wall was heterogeneous in terms of its density (which varied with the thickness), the breaking strength of all the alternating-patterned Biosheets increased almost linearly with the thickness within the range of the thickness of clinically used glutaraldehyde-treated pericardium as a control, and was larger than that of human aortic valve leaflets. Therefore, the alternating-patterned Biosheets have potential for use in an alternative aortic leaflet material in AVNeo.
       
  • Changes in inertial parameters of the lower limb during the impact phase
           of dynamic tasks
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Laura-Anne M. Furlong, Dimitrios Voukelatos, Pui Wah Kong, Matthew T.G. PainAbstractMechanical analysis at the whole human body level typically assumes limbs are rigid bodies with fixed inertial parameters, however, as the human body consists mainly of deformable soft tissue, this is not the case. The aim of this study was to investigate changes in the inertial parameters of the lower limb during landing and stamping tasks using high frequency three-dimensional motion analysis. Seven males performed active and passive drop landings from 30 and 45 cm and a stamp onto a force plate. A sixteen-camera 750 Hz Vicon system recorded markers for standard rigid body analysis using inverse kinematics in Visual 3D and 7 × 8 and 7 × 9 marker arrays on the shank and thigh. Frame by frame segment volumes from marker arrays were calculated as a collection of tetrahedra using the Delaunay triangulation method in 3D and further inertial parameters were calculated using the method of Tonon (2004). Distance between the centres of mass (COM) of the rigid and soft tissues changed during impact in a structured manner indicative of a damped oscillation. Group mean amplitudes for COM motion of the soft tissues relative to the rigid body of up to 1.4 cm, and changes of up to 17% in moment of inertia of the soft tissue about the rigid body COM were found. This study has shown that meaningful changes in inertial parameters can be observed and quantified during even moderate impacts. Further examination of the effects these could have on movement dynamics and energetics seems pertinent.
       
  • Biomechanical implications of the fenestration structure after thoracic
           endovascular aortic repair
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Yonghui Qiao, Le Mao, Ting Zhu, Jianren Fan, Kun LuoAbstractThe inadequate landing zone during thoracic endovascular aortic repair (TEVAR) could be resolved by fenestration technology. The fenestration structure consists of a main endograft and a left subclavian artery (LSA) stent-graft. The purpose of this study is to assess the biomechanical implications of the protruding segment (PS) of the LSA stent-graft after TEVAR with in situ fenestration (ISF-TEVAR). The PS is characterized by the protruding length and centerline angle between the LSA and PS. An idealized three-dimensional geometric model of the human aorta was constructed as the reference benchmark. We designed nine postoperative aortic geometries with different protruding lengths (5, 10, 15 mm) and centerline angles (-20°, 0°, +20°). The blood was assumed to be non-Newtonian and the three-element Windkessel model was applied to reproduce physiological pressure waveforms. The interaction between the blood and vessel wall was captured by a two-way fluid-structure method. We also considered the impact of the fenestration structure on the vessel wall. Long protruding length (15 mm) and the retrograde angle (+20°) result in a markedly reduced LSA flow ratio (1.3%). There is a pressure difference between the inner and outer walls of the PS. The region around the PS is more prone to thrombosis. The flow stability and turbulence intensity of downstream blood of the PS gradually deteriorate. The largest deformed region moves from the aortic arch to the ascending aorta after ISF-TEVAR. The postoperative hemodynamics largely depends on the protruding length and angle of the LSA stent-graft. The configurations should be carefully controlled during ISF-TEVAR.
       
  • Chronic ankle instability patients exhibit higher variability in lower
           extremity joint-coupling variability during drop vertical jumps
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): C.C. Herb, S. Blemker, S. Saliba, J. Hart, J. HertelAbstractChronic ankle instability (CAI) has been associated with biomechanical alterations during landing tasks. While joint coupling differences have been reported during gait in patients with CAI, there is no known research assessing joint coupling during a drop-vertical jumping (DVJ). Joint coupling variability measure may provide information on the sensorimotor health of these patients. The purpose of this study was to compare lower extremity joint coupling variability during a DVJ between patients with CAI and controls. Twenty-eight young, active individuals (CAI:n = 14, Control:n = 14) participated in the study. A 3D motion capture system was used to collect kinematics during 15 drop-vertical jump trials. A vector coding analysis was used to assess the variability in the following joint couples: knee sagittal-ankle frontal, knee sagittal-ankle sagittal, hip frontal-ankle frontal, and hip frontal-ankle sagittal. The CAI group had higher joint coupling variability in hip frontal-ankle sagittal, knee sagittal-ankle frontal and knee sagittal-ankle sagittal planes both prior to and following ground contact during the drop vertical jumps. These changes indicate potential adaptations to the constraint of CAI and the task of the DVJ. Higher variability may reflect an attempt by the subjects to explore alternate movement strategies or reflect poor sensorimotor control strategies. Clinicians should consider the challenges of DVJ during rehabilitation as they create a unique task constraint.
       
  • A novel test reliably captures hip and knee kinematics and kinetics during
           unanticipated/anticipated diagonal hops in individuals with anterior
           cruciate ligament reconstruction
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Ashokan Arumugam, Jonas L. Markström, Charlotte K. HägerAbstractUnanticipated land-and-cut maneuvers might emulate lower limb mechanics associated with anterior cruciate ligament (ACL) injury. Reliability studies on landing mechanics of such maneuvers are however lacking. This study investigated feasibility and within-session reliability of landing mechanics of a novel one-leg double-hop test, mimicking a land-and-cut maneuver, in individuals with ACL reconstruction (ACLR). Our test comprised a forward hop followed by a diagonal hop in either of two directions (medial/lateral) under anticipated and unanticipated conditions. Twenty individuals with a unilateral ACLR (aged 24.2 ± 4.2 years, 0.7–10.8 years post-surgery) performed three successful hops/direction per leg. We determined reliability (intraclass correlation coefficient [ICC]) and agreement (standard error of measurement [SEM]) of 3-dimensional hip and knee angles and moments during the deceleration phase of the land-and-cut maneuver (vulnerable for non-contact ACL injuries). Mean success rate for unanticipated hops was 71–77% and for anticipated hops 91–95%. Both limbs demonstrated moderate-excellent reliability (ICC 95% confidence intervals: 0.50–0.99) for almost all hip and knee peak angles and moments in all planes and conditions, with a few exceptions: poor-good reliability for hip and knee frontal and/or transverse plane variables, especially for lateral diagonal hops. The SEMs were ≤5° and ≤0.23 N·m/kg·m for most peak angles and moments, respectively. Our test seems feasible and showed satisfactory reliability for most hip and knee angles and moments; however, low knee abduction and internal rotation angles and moments, and moderate reliability of these moments deserve consideration. The test appears to challenge dynamic knee control and may prove valuable in evaluation during knee rehabilitation.
       
  • Comparison of three kinematic gait event detection methods during
           overground and treadmill walking for individuals post stroke
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Margaret A. French, Corey Koller, Elisa S. ArchAbstractDetecting gait events using ground reaction forces (i.e. kinetic detection) is the gold standard, but it is not always possible. Kinematic methods exist; however, accuracy of these methods in stroke survivors during treadmill and overground walking is unknown. Thus, this study compared the accuracy of three kinematic methods during overground and treadmill walking in stroke survivors. Heel strike and toe off were calculated bilaterally using three kinematic methods (horizontal sacral-heel distance, horizontal ankle-heel distance, and horizontal velocity) and a kinetic method for ten stroke survivors. We calculated true and absolute error for each kinematic method relative to the kinetic method to evaluate accuracy. Repeated-measures ANOVAs compared the absolute error between the different methods for each condition. There was a significant effect of method for all conditions except heel strike during treadmill walking. Post hoc tests showed ankle-heel distance detected heel strike with significantly less error than the other methods during overground walking (p 
       
  • Hamstring muscle-tendon unit lengthening and activation in instep and
           cut-off kicking
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Liwen Zhang, Hanjun Li, William E Garrett, Hui Liu, Bing YuAbstractHamstring muscle strain injury is one of the most common injuries in sports involving sprinting and kicking. Studies examining hamstring kinematics and activations are rich for sprinting but lacking for kicking. The purpose of this study was to examine kinematics and activations of hamstring muscles in instep and cut-off kicking tasks frequently performed in soccer. Videographic and electromyographic (EMG) data were collected for 11 male soccer-majored college students performing the two kicking tasks. Peak hamstring muscle-tendon unit lengths, elongation velocities, and maximum linear envelop EMG data were identified and compared among hamstring muscles and between kicking tasks. Hamstring muscles exhibited activated elongations before and after the contact of the kicking foot with the ball. The muscle-tendon unit lengths peaked in the follow-through phase. The peak elongation velocity of the semimembranosus was significantly greater than that of the semitendinosus and biceps femoris (p = 0.001). The maximum linear envelop EMG of the biceps femoris was significantly greater than that of the semimembranosus (p = 0.026). The potential for hamstring injury exists in the follow-through phase of each kicking task. The increased hamstring muscle-tendon unit elongation velocities in kicking tasks may explain the more severe hamstring injuries in kicking compared to sprinting.
       
  • An inverse model of the mechanical response of passive skeletal muscle:
           Implications for microstructure
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Théo Valentin, Ciaran SimmsAbstractThe constitutive response of passive skeletal muscle is important for many human body modelling applications, but modelling the tension-compression asymmetry and the anisotropy observed in ex-vivo samples is challenging. Existing microstructural models do not capture the full three-dimensional response while models suitable for application in finite element environments mostly have a limited microstructural basis and cannot capture the observed Poisson’s ratios. The aim of this paper is to derive an inverse model based on the microstructure of a skeletal muscle that can predict its passive mechanical response. The model parameters and predictions were derived and assessed by comparison with published experimental stress-strain response and Poisson’s ratio data. Results show a close match for both predicted stress-strain response for fibre and cross-fibre direction deformations and similar Poisson’s ratio values. Some microstructural observations which strengthen our understanding of the role of the collagen network and intramuscular pressure are also provided.
       
  • Analysis of the aerodynamic sound of speech through static vocal tract
           models of various glottal shapes
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Lukas Schickhofer, Mihai MihaescuAbstractThe acoustic spectrum of our voice can be divided into harmonic and inharmonic sound components. While the harmonic components, generated by the oscillatory motion of the vocal folds, are well described by reduced-order speech models, the accurate computation of the inharmonic components requires high-order flow simulations, which predict the vortex shedding and turbulent structures present in the shear layers of the glottal jet. This study characterizes the dominant frequencies in the unsteady flow of the intra- and supraglottal region. A realistic vocal tract geometry obtained through magnetic resonance imaging (MRI) is applied for the numerical domain, which is locally modified to account for different convergent and divergent glottal angles. Both time-averaged and fluctuating values of the flow variables are computed and their distribution at various glottal shapes is compared. The impact of the registered modes in the unsteady flow on the acoustic far field is computed through direct compressible flow simulations. Furthermore, acoustic analogies are applied to localize the sources of the aerodynamically generated sound.
       
  • Knee joint stiffness following immobilization and remobilization: A study
           in the rat model
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Haodong Zhou, Guy Trudel, Louis Goudreau, Odette LaneuvilleAbstractDeficits in extension can limit the function and performance of the knee joint. The range of motion (ROM) deficit in knee extension is often measured and reported at a single torque value applied in the flexion-extension axis. This static measurement of ROM omits key details about the biomechanical properties of the knee, such as its mechanical stiffness. Our objectives were (1) to quantify knee extension stiffness after various periods of immobilization and remobilization, and (2) to evaluate how stiffness correlated with the length of the posterior knee capsule. Two hundred fifty-six male Sprague Dawley rats had one knee immobilized at a 45° angle in flexion using a Delrin® plate for 6 different durations ranging from 1 to 32 weeks. Remobilization was initiated by removing the plate and lasted for 0–48 weeks. The contralateral knee and unoperated age-matched rats were used as controls. An automated arthrometer extended the knee at four pre-determined torques and these data were used to calculate mechanical stiffness. The stiffness of knees immobilized for 8 or more weeks was significantly greater than controls and persisted despite remobilization (p 
       
  • Sensitivity of the knee joint response, muscle forces and stability to
           variations in gait kinematics-kinetics
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): M. Sharifi, A. Shirazi-Adl, H. MarouaneAbstractSensitivity analysis of the knee joint response to variations in gait kinematics-kinetics as reported in the literature is crucial for improved understanding and more effective prevention-treatment strategies. Using our validated finite element-musculoskeletal (FE-MS) model of lower extremity, we investigate the sensitivity of knee anterior cruciate ligament (ACL), muscle, and contact forces plus stability to the reported scatter in asymptomatic gait data. Three highly loaded stance instants (25, 50 and 75%) with five levels (mean, ±0.5SD and ±SD) for each of six knee joint angles-moments are used employing Taguchi approach (25 experiments) and regression equations. ACL force drops significantly at larger flexion angles (all periods) and smaller internal moment (at 75% only) but increases with the flexion moment. Tibiofemoral (TF) medial-lateral contact force partitioning is found, contrary to the common claim, most sensitive to changes in the adduction angle and not in the adduction moment. Total TF contact force increases significantly at greater moments (but not angles), especially in the sagittal plane. Forces in lateral hamstrings are significantly influenced by changes in adduction angles-moments. Larger flexion moments (at 25 and 50%) significantly increase forces in quadriceps and on patellofemoral (PF) contact. Sagittal moment, adduction moment (at 75%) and flexion angle (at 25%) contribute most to the joint stability. A strong inverse correlation exists between the joint stability and the total TF compression force. These findings can be exploited to adapt and modify intact, injured and reconstructed knee joint responses during gait.
       
  • The effects of rehabilitation on the biomechanics of patients with
           athletic groin pain
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): S.J. Gore, A. Franklyn-Miller, C. Richter, E. King, E.C. Falvey, K. MoranAbstractThis study sought to investigate the kinematic and kinetic variables that change in patients with athletic groin pain (AGP) after a successful exercise intervention. The kinematic and kinetic measures of subjects with AGP (n = 65) that completed a lateral hurdle hop, pre and post an exercise rehabilitation program were compared to a control group of matched uninjured individuals (n = 50). Analysis of Characterising Phases was used to identify differences in kinematic and kinetic measures between the groups. AGP subjects returned to pain-free participation in sport in a median time of 9.14 weeks (5.14‐29.0). In total 18 different biomechanical variables were significantly different between the AGP group and the uninjured group pre-rehabilitation. Of these, seven variables were no longer significantly different between the AGP group post-rehabilitation and the uninjured group. These seven variables may represent the factors most related to return to play in this cohort and are potential targets for rehabilitation.
       
  • The ability of surface electromyography to represent supraspinatus
           anterior and posterior partition activity depends on elevation angle, hand
           load and plane of elevation
    • Abstract: Publication date: 23 January 2020Source: Journal of Biomechanics, Volume 99Author(s): Alan C. Cudlip, Soo Y. Kim, Clark R. DickersonAbstractThis study examined relationships between electromyography recorded from indwelling electrodes of the anterior and posterior supraspinatus and a surface supraspinatus electrode. Twenty male and twenty female participants completed full range humeral elevations in three planes of elevation (0/40/90°) and three hand loads (unloaded/20%/40% of maximal elevation strength). EMG activation was combined with motion capture to determine activation at instantaneous activation angles, and linear regressions of anterior and posterior indwelling electrodes relative to the surface electrode determined relationships between these signals. Regressions between surface and indwelling signals were affected by plane of elevation, elevation angle, load intensity and participant sex, but no interactions existed. Surface signals underestimated activation at low elevation angles for both regions, and up to 45% in the anterior supraspinatus (p 
       
  • Piezoelectricity in the Intervertebral Disc
    • Abstract: Publication date: Available online 9 January 2020Source: Journal of BiomechanicsAuthor(s): Philip Poillot, Joseph O'Donnell, David T. O'Connor, Ehtsham Ul Haq, Christophe Silien, Syed A.M. Tofail, Jacques M. HuygheAbstractLower back pain is a major global health challenge that can often be caused by degeneration of the Intervertebral Disc (IVD). While IVD biomechanics are a key factor in the degenerative cycle, many mechanotransduction pathways remain unknown, in particular the electro-mechanical coupling in the loaded tissue. However, despite evidence for a role in the mechanically-induced remodelling of similar tissue, piezoelectricity has been overlooked in the IVD. In this study, we investigate the piezoelectric properties of the Annulus Fibrosus (AF) and the Nucleus Pulposus (NP) by measuring the direct piezoelectric effect of mechanically-induced electrical potential change. To verify these findings, we conducted Piezoresponse Force Microscopy (PFM) to measure the inverse effect of electrically-induced deformation. We demonstrate that, for the first time, piezoelectricity is generated throughout the IVD. Piezoelectric effects were greater in the AF than the NP, owing to the organised collagen networks present. However, the piezoresponse found in the NP indicates piezoelectric properties of non-collagenous proteins that have not yet been studied. The voltage generated by longitudinal piezoelectricity in-vivo has been calculated to be ∼1 nV locally, indicating that piezoelectric effects may directly affect cell alignment in the AF and may work in conjunction with streaming potentials throughout the IVD. In summary, we have highlighted an intricate electro-mechanical coupling that appears to have distinct physiological roles in the AF and NP. Further study is required to elucidate the cell response and determine the potential role of piezoelectric effects in regeneration and preventative measures from degeneration.
       
  • Stair negotiation behaviour of older individuals: Do step dimensions
           matter'
    • Abstract: Publication date: Available online 9 January 2020Source: Journal of BiomechanicsAuthor(s): Thijs M.A. Ackermans, Natasha C. Francksen, Raul V. Casana-Eslava, Carolyn Lees, Vasilios Baltzopoulos, Paulo J.G. Lisboa, Mark A. Hollands, Thomas D. O'Brien, Constantinos N. MaganarisAbstractStair falls are a major health problem for older people. Most studies on identification of stair fall risk factors are limited to staircases set in given step dimensions. However, it remains unknown whether the conclusions drawn would still apply if the dimensions had been changed to represent more challenging or easier step dimensions encountered in domestic and public buildings. The purpose was to investigate whether the self-selected biomechanical stepping behaviours are maintained when the dimensions of a staircase are altered. Sixty-eight older adults (>65 years) negotiated a seven-step staircase set in two step dimensions (shallow staircase: rise 15cm, going 28cm; steep staircase: rise 20cm, going 25cm). Six biomechanical outcome measures indicative of stair fall risk were measured. K-means clustering profiled the overall stair-negotiating behaviour and cluster profiles were calculated. A Cramer’s V measured the degree of association in membership between clusters. The cluster profiles revealed that the biomechanically risky and conservative factors that characterized the overall behaviour in the clusters did not differ for the majority of older adults between staircases for ascent and descent. A strong association of membership between the clusters on the shallow staircase and the steep staircase was found for stair ascent (Cramer’s V: 0.412, p
       
  • Spinal Sagittal Alignment Goals based on Statistical Modelling and
           Musculoskeletal Simulations
    • Abstract: Publication date: Available online 9 January 2020Source: Journal of BiomechanicsAuthor(s): Sebastiano Caprara, Greta Moschini, Jess G. Snedeker, Mazda Farshad, Marco SentelerAbstractThe definition of target alignment for spinal fusion surgery follows anatomical criteria and strongly relies on surgical experience. However, the optimal patient-specific alignment often remains unknown. Statistical models could provide information about physiological alignments, and musculoskeletal models are powerful tools to investigate biomechanics. We aimed to statistically predict alignments and hypothesized they would be biomechanically favorable.A statistical model was trained with 60 annotated radiographs to predict physiological sagittal alignment based on position of femoral heads and sacrum. Predicted alignments for 11 back pain patients were clinically evaluated in terms of balance and compared to Original alignments. The normative ranges for spinal balance parameters were obtained from Surgimap™. Musculoskeletal loads were furthermore simulated in upright standing and 30° forward flexion, using alignment-specific musculoskeletal models.For the majority of Predicted alignments (n=9) at least two of three investigated balance parameters were within the normative range, as opposed to the minority of the Original alignments (n=4). Predicted alignments resulted in significantly lowered overall muscle activity and compressive loads (all levels, both postures). Shear force magnitudes in upright standing decreased significantly at levels L1L2 (-68 N) and L2L3 (-69 N) and clearly yet not significantly at L3L4 (-39 N) and L4L5 (-152 N). Shear loads at level L5S1 remained the same. In flexed postures identical trends were observed.The statistical model was able to predict spinal alignments that led to both improved balance and reduced musculoskeletal loads. Further studies are needed to investigate clinical validity of such models.
       
  • Automatic segment filtering procedure for processing non-stationary
           signals
    • Abstract: Publication date: Available online 9 January 2020Source: Journal of BiomechanicsAuthor(s): Daniel J. Davis, John H. ChallisAbstractComputing time derivatives is a frequent stage in the processing of biomechanical data. Unfortunately, differentiation amplifies the high frequency noise inherent within the signal hampering the accuracy of signal derivatives. A low-pass Butterworth filter is commonly used to reduce the sampled signal noise prior to differentiation. One hurdle lies in selecting an appropriate filter cut-off frequency which retains the signal of interest while reducing deleterious noise. Most biomechanics data processing approaches utilize the same cut-off frequency for the whole sampled signal, but the frequency components of a signal can vary with time. To accommodate such signals, the Automatic Segment Filtering Procedure (ASFP) is proposed which uses different automatically determined Butterworth filter cut-off frequencies for separate segments of a sampled signal. The Teager-Kaiser Energy Operator of the signal is computed and used to determine segments of the signal with different energy content. The Autocorrelation-Based Procedure (ABP) is used on each of these segments to determine filter cut-off frequencies. This new procedure was evaluated by estimating acceleration values from the test data set of Dowling (1985). The ASFP produced a root mean square error (RMSE) of 16.4 rad.s-2 (26.6%) whereas a single ABP determined filter cut-off frequency applied to the whole Dowling (1985) signal, representing the common approach, produced a RMSE of 25.5 rad.s-2 (41.4%). As a point of comparison, a Generalized Cross-Validated Quintic Spline, a common non-Butterworth filter, produced a RMSE of 23.6 rad.s-2 (38.4%). This new automatic approach is advantageous in biomechanics for preserving high frequency content of non-stationary signals.
       
  • Non-periodicity of blood flow and its influence on wall shear stress in
           the carotid artery bifurcation: an in vivo measurement-based computational
           study
    • Abstract: Publication date: Available online 9 January 2020Source: Journal of BiomechanicsAuthor(s): Xindong Zhou, Lekang Yin, Lijian Xu, Fuyou LiangAbstractAlthough arterial blood flow is physiologically non-periodic under resting conditions, periodic flow assumption has been widely adopted in most hemodynamic studies. So far, it remains unclear how the non-periodicity of blood flow would influence local hemodynamic parameters, especially wall shear stress (WSS) that associates closely with endothelial function and vascular disease. In this study, numerical simulations of blood flows in sixteen normal carotid artery bifurcations were performed under measured non-periodic and averaged periodic flow conditions, respectively, with the obtained results being compared in terms of five typical WSS metrics (i.e., mean WSS (MWSS), time-averaged WSS (TAWSS), oscillatory shear index (OSI), transverse WSS (transWSS), and average temporal gradient of WSS (WSSTG)) in the atheroprone low-WSS regions. It was found that simplifying the physiologically non-periodic flow condition into a periodic one did not significantly alter the major features of WSS distribution, but resulted in underestimations of some WSS metrics. Specifically, the degree of underestimation was largest (27.2% ± 8.3%) for WSSTG, smallest (0.5% ± 0.4%) for MWSS, while moderate (5.1% ± 3.2% ~ 9.2% ± 4.1%) for other WSS metrics. Statistical analyses revealed that the cycle-to-cycle variability of flow velocity waveform (var-V) and the planarity of internal carotid artery correlated strongly with the periodic flow assumption-induced underestimations of WSS metrics. These findings suggest that taking the non-periodic characteristic of blood flow into consideration could be important for studying hemodynamics in arteries with a large var-V or specific morphological characteristics, especially when WSSTG is the main hemodynamic parameter of concern.
       
  • New insights on the proximal femur biomechanics using Digital Image
           Correlation
    • Abstract: Publication date: Available online 8 January 2020Source: Journal of BiomechanicsAuthor(s): Yekutiel Katz, Zohar YosibashAbstractFinite element analyses (FEAs) of human femurs are mostly validated by ex-vivo experimental observations. Such validations were largely performed by comparing local strains at a small subset of points to the gold standard strain gauge (SG) measurements. A comprehensive full field validation of femoral FEAs including both strains and displacements using digital image correlation (DIC) full field measurements, especially at medial and lateral surfaces of the neck that experience the highest strains, provide new insights on femurs’ mechanical behavior.Five cadaver femurs were loaded in stance position and monitored at the shaft and neck using two DIC systems simultaneously. DIC strains were compared to SG measurements at a limited number of locations so to corroborate DIC measurements by the gold standard technique. These were used to quantitatively assess the validity of FEA strains prediction especially at the neck where fracture usually occurs.Strains measured by DIC correspond well to the SG observations. An excellent agreement was observed between DIC and FEA predicted strains excluding the superior neck surface: FE=1.02×DIC-17,r2=0.977. At the superior neck however, strains were not well predicted by FEA models: Although the FEA predicted high strains at the ’saddle region’, these were not observed experimentally. On the other hand, strain concentration has been measured by DIC at numerous vessel holes which were not represented by FE models. Since fractures usually initiates at thesubcapital region in stance position ex-vivo experiments, where numerus of vessel holes exist, these vessel holes may be required to be accounted for in future FE models so to allow a better estimation of the fracture load. Full field measurements are mandatory to allow a better validation of fracture load and location predictions which are of high clinical importance.
       
  • Direct muscle electrical stimulation as a method for the in vivo
           assessment of force production in m. abductor hallucis
    • Abstract: Publication date: Available online 7 January 2020Source: Journal of BiomechanicsAuthor(s): Andrei L. Pérez Olivera, Daniel F. Alzapiedi, Matthew C. Solan, Kiros Karamanidis, Katya N. Mileva, Darren C. JamesAbstractIn vivo assessment of the force-generating capacity of m. abductor hallucis (AbH) is problematic due to its combined abduction-flexion action and the inability of some individuals to voluntarily activate the muscle. This study investigated direct muscle electrical stimulation as a method to assess isometric force production in AbH about the 1st metatarsal phalangeal joint (1MPJ) at different muscle-tendon lengths, with the aim of identifying an optimal angle for force production. A 7s stimulation train was delivered at 20Hz pulse frequency and sub-maximal (150% motor threshold) intensity to the AbH of the left foot in 16 participants whilst seated, and with the Hallux suspended from a force transducer in 0°,5°,10°,15° and 20° 1MPJ dorsal flexion. Reflective markers positioned on the foot and force transducer were tracked with 5 optical cameras to continuously record the force profile and calculate the external 1MPJ joint flexion moment at each joint configuration. A parabolic relationship was found between AbH force production and 1MPJ configuration. The highest 1MPJ joint moments induced by electrical stimulation were found between 10° and 15° of Hallux dorsal flexion. However, the joint angle (p
       
  • Total disc arthroplasties alter the characteristics of the instantaneous
           helical axis of the cervical functional spinal units C3/C4 and C5/C6
           during flexion and extension in in vitro conditions
    • Abstract: Publication date: Available online 7 January 2020Source: Journal of BiomechanicsAuthor(s): Paul Jonathan Roch, Markus Wagner, Jan Weiland, Stefan Spiering, Wolfgang Lehmann, Dominik Saul, Lukas Weiser, Lennart Viezens, Martin Michael WachowskiAbstractTotal disc arthroplasty (TDA) increases the risk of adjacent segment disease (ASD). Kinematic analyses are necessary to compare the intact condition (IC) with alterations after TDA to develop better prostheses. A well-established 6D measuring apparatus (resolution 
       
  • Quantifying deformations and strains in human intervertebral discs using
           Digital Volume Correlation combined with MRI (DVC-MRI)
    • Abstract: Publication date: Available online 3 January 2020Source: Journal of BiomechanicsAuthor(s): S. Tavana, J.N. Clark, J. Prior, N. Baxan, S.D. Masouros, N. Newell, U. HansenAbstractPhysical disruptions to intervertebral discs (IVDs) can cause mechanical changes that lead to degeneration and to low back pain which affects 75% of us in our lifetimes. Quantifying the effects of these changes on internal IVD strains may lead to better preventative strategies and treatments. Digital Volume Correlation (DVC) is a non-invasive technique that divides volumetric images into subsets, and measures strains by tracking the internal patterns within them under load. Applying DVC to MRIs may allow non-invasive strain measurements. However, DVC-MRI for strain measurements in IVDs has not been used previously. The purpose of this study was to quantify the strain and deformation errors associated with DVC-MRI for measurements in human IVDs.Eight human lumbar IVDs were MRI scanned (9.4T) for a ‘zero-strain study’ (multiple unloaded scans to quantify noise within the system), and a loaded study (2mm axial compression). Three DVC methodologies: Fast-Fourier transform (FFT), direct correlation (DC), and a combination of both FFT and DC approaches were compared with subset sizes ranging from 8 to 88 voxels to establish the optimal DVC methodology and settings which were then used in the loaded study.FFT+DC was the optimal method and a subset size of 56 voxels (2520 micrometers) was found to be a good compromise between errors and spatial resolution. Displacement and strain errors did not exceed 28 µm and 3000 microstrain, respectively.These findings demonstrate that DVC-MRI can quantify internal strains within IVDs non-invasively and accurately. The method has unique potential for assessing IVD strains within patients.
       
  • A Combined Method for Binning Coupling Angles to Define Coordination
           Patterns
    • Abstract: Publication date: Available online 3 January 2020Source: Journal of BiomechanicsAuthor(s): John Beitter, Young-Hoo Kwon, Kirsten Tulchin-FrancisAbstractThe vector coding technique has been used to quantify coordination of two joints, segments, and/or planes during cyclic activities, such as walking. Coordination patterns can be identified by categorizing the tangent lines of an angle-angle plot by their direction, termed “coupling angle binning” or “phase binning”. In the literature the ranges of directions, or “bins”, originally divided by Chang et al. and more recently by Needham et al. have different strengths. Chang’s method identifies general patterns with large bins while Needham’s method identifies a dominant joint or segment in the pattern. This study created a novel method that incorporates bin categories from both methods, and therefore recognizes both general patterns and a dominant contributor when appropriate. This new method, the TSRH method, as well as the two existing methods, were used to quantify knee-ankle coordination in the sagittal plane for healthy individuals and an individual with clubfoot during gait. Similarities and differences in classification between methods were compared and further investigated by interpreting the uncoupled angular data. Each method was then used to evaluate sagittal-coronal coordination of the forefoot in an individual with clubfoot during gait. This was done to demonstrate across-plane coordination analysis, to confirm that the advantages of the combined method extend to coupling pairs with like ranges of motion, and to present a clinical application. It was found that the TSRH binning methods provides a more complete description of coordination by including coordination categories defined by both the Chang and Needham method.
       
  • Low back pain affects coordination between the trunk segments but not
           variability during running
    • Abstract: Publication date: Available online 3 January 2020Source: Journal of BiomechanicsAuthor(s): Alexandre R. M. Pelegrinelli, Leandro C. Guenka, Mariana F. Silva, Aline C. Carrasco, Felipe A. Moura, Jefferson R. CardosoAbstractThis study aimed to analyze the coordination and variability between the thorax, lumbar, and pelvis segments in runners with chronic low back pain group (LBPG) and matched control group (CG). Twenty-six recreational runners were evaluated on a treadmill at 3.3 m/s. The coordination of the pelvis–lumbar and lumbar–thorax in all three planes and between the transverse and frontal plane of the lumbar segment were evaluated using the vector coding technique. Coordination was analyzed via histograms with the percentage of each pattern and the coupling angle during the cycle. The variability coordination was calculated from the angular deviation between the cycles. Differences were observed in the coordination patterns and in the coupling angle during the cycle. Between the pelvis–lumbar in the frontal plane, the LBPG (x¯= 50.6 % (SD = 10.7)) presented more in-phase pattern than the CG (38.6 % (8.7; P = 0.05). For the lumbar–thorax, differences occurred in all planes. Between the frontal–transverse plane of the lumbar segment, the LBPG (27.6 % (7.9)) presented more in-phase pattern than the CG (38.6 % (8.7); P = 0.02). The variability did not demonstrate the differences between the groups; these differences were observed in coordination between the lumbar and adjacent segments in all planes. The model of rigid segments and the coordination analyses were sensitive to detect these differences, and the presence of more in-phase patterns could be related to the protection mechanism in order to avoid painful movements.
       
  • Effects of age and sex on trunk motor control
    • Abstract: Publication date: Available online 3 January 2020Source: Journal of BiomechanicsAuthor(s): M. Griffioen, J.H. van DieënAbstractThe goal of the present study was to assess the effects of age and sex on trunk motor control. Fifty healthy adults (aged between 19 and 67 years, 28 males) participated in this study. Trunk motor control was assessed using force-controlled perturbations directly applied to the trunk. Admittance (inverse of lumped intrinsic and reflexive impedance) decreased with age and tended to be lower in females than males. The age effect on admittance was due to increasing intrinsic stiffness and damping with age, while intrinsic damping and position- and velocity feedback gains were lower in females than males. Feedback delays were not dependent on age. The decrease of trunk admittance with age is most likely due to increasing levels of antagonistic co-activation. Trunk admittance was (just) not significantly different between females and males, in spite of lower feedback gains and damping, possibly due to differences in trunk mass between sexes. These results imply that age and sex differences should be considered when assessing the relationship between back pain and trunk motor control.
       
  • Comparison of a portable balance board for measures of persistence in
           postural sway
    • Abstract: Publication date: Available online 3 January 2020Source: Journal of BiomechanicsAuthor(s): Zachary S. Meade, Vivien Marmelat, Mukul Mukherjee, Takashi Sado, Kota Z. TakahashiAbstractMeasuring postural sway is important for determining functional ability or risk of falling. Gathering postural sway measures outside of controlled environments is desirable for reaching populations with limited mobility. Previous studies have confirmed the accuracy of the magnitude of postural sway using the Nintendo Wii Balance Board (WBB). However, it is unclear if the WBB can accurately measure persistence of postural sway, i.e., the pattern of center-of-pressure fluctuations over time. The purpose of this study was to compare measures of persistence of postural sway (through detrended fluctuation analysis) using WBB and a force platform (FP). Seventeen healthy individuals performed three standing conditions: eyes open, eyes closed, and one-leg standing. The WBB (30 Hz) was placed on top on the FP (600 Hz) to collect data simultaneously, then the FP data were downsampled to 100 Hz and 30 Hz. The agreement between WBB and FP for measures of postural sway were influenced by the sampling rate and postural sway direction. Intraclass correlation coefficient was excellent (range: 0.953 – 0.998) for long-term scaling regions in the anterior-posterior direction, but lower (range: 0.352 – 0.877) and inconsistent for medial-lateral direction and short-term scaling regions. The three comparison groups (WBB at 30 Hz, FP at 30 Hz, and FP at 100 Hz) showed dissimilar abilities in detecting differences in persistence of postural sway. In summary, the WBB is accurate for quantifying persistence of postural sway measurements in long-term scaling regions in the AP direction, but has limitations for short-term scaling regions and the ML direction.
       
  • Dynamic interactions between lumbar intervertebral motion segments during
           forward bending and return
    • Abstract: Publication date: Available online 3 January 2020Source: Journal of BiomechanicsAuthor(s): Breen Alexander, Breen AlanAbstractContinuous dynamic multi-segmental studies of lumbar motion have added depth to our understanding of the biomechanics of back pain, but few have attempted to continuously measure the proportions of motion accepted by individual levels. This study attempted to compare the motion contributions of adjacent lumbar levels during an active weight bearing flexion and return protocol in chronic, non-specific low back pain (CNSLBP) patients and controls using quantitative fluoroscopy (QF).Eight CNSLBP patients received QF during guided standing lumbar flexion. Dynamic motion sharing of segments from L2 to S1 were calculated and analysed for interactions between levels. Eight asymptomatic controls were then matched to the 8 patients for age and sex and their motion sharing patterns compared.Share of intersegmental motion was found to be consistently highest at L2-L3 and L3-L4 and lowest at L5-S1 throughout the motion in both groups, with the exception of maximum flexion where L4-L5 received the greatest share.Change in motion sharing occurred throughout the flexion and return motion paths in both participant groups but tended to vary more at L4-L5 in patients (p
       
  • Sensitivity analysis of muscle properties and impact parameters on head
           injury risk in american football
    • Abstract: Publication date: Available online 3 January 2020Source: Journal of BiomechanicsAuthor(s): Jonathan D. Mortensen, Anita N. Vasavada, Andrew S. MerryweatherAbstractHead injuries frequently occur in American football and other contact sports. Uncertainty on the effects of cervical muscle properties on head injury risk may be due to the limitations of previous observational studies. This simulation study employs a musculoskeletal model of the head and neck to investigate the effect of several factors related to head injury metrics in American Football. These factors include isometric muscle strength, the eccentric multiplier (which is related to the athlete’s ability to apply greater muscle force during eccentric contractions), posture, muscle activation patterns, and impact properties. Impact properties were based on the literature and tuned to reproduce peak linear and rotational accelerations of the skull. We hypothesized that active neck muscles significantly reduce head injury metrics. We systematically altered each model parameter to test our hypothesis. We then determined which model parameters affect head injury metrics the most. The results of this study indicate that active neck muscles have a statistically significant effect on head injury metrics. Increasing muscle strength and eccentric multiplier also resulted in a statistically significant reduction of head injury metrics. However, posture prior to impact had a much stronger effect than any other factor on head injury metrics. A comprehensive approach to athlete training protocols is recommended, including exercises aimed at increasing eccentric muscle strength and preparation for impacts. Future studies should investigate how targeted muscle strengthening and impact training (i.e. activation patterns and posture) modifies risk.
       
  • Effect of Investigator Observation on Gait Parameters in Individuals with
           Stroke
    • Abstract: Publication date: Available online 3 January 2020Source: Journal of BiomechanicsAuthor(s): Marzieh M. Ardestani, T. George HornbyAbstractImprovements in gait speed following various training paradigms applied to patients post-stroke does not always lead to changes in walking performance, defined as gains in daily stepping activity. We hypothesized that testing conditions, specifically the presence of an observer, influences patient behaviors and resultant outcomes may overestimate their true walking capacity. This potential Hawthorne effect on spatiotemporal and biomechanical measures of locomotor function in individuals post-stroke has not been assessed previously.Fifteen ambulatory individuals with chronic stroke wore instrumented insoles and performed two separate normal-pace walking assessments, including unobserved conditions during which participants were unattended and unaware of data collection, and observed conditions with an investigator present. Gait analysis was conducted outside of a laboratory setting using instrumented insoles equipped with a 3D accelerometer and pressure sensors which captured the spatiotemporal kinematics, vertical ground reaction forces and foot acceleration. Data were compared using paired comparisons, with subsequent correlation and stepwise regression analyses to explore potential associations between Hawthorne-induced changes in walking strategies, gait speed and locomotor performance (daily stepping).Except for cadence, other measures of spatiotemporal parameters and swing kinematics (acceleration) were not significantly different between observed vs unobserved conditions. However, analyses of ground reaction forces revealed significantly greater paretic limb loading (Δ1st peak = 1.5±1.6 N/Kg Δ2nd peak=1.4±1.8 N/Kg; p
       
  • Peak of neuromuscular activation and angle where it occurs during bench
           press exercise performed with different repetition number and duration in
           resistance trained individuals
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): L.T. Lacerda, M.H. Chagas, M.S. Gurgel, R.C.R. Diniz, M.B. Lanza, G.H.C. Peixoto, A.G.P. Andrade, F.V. LimaAbstractThe present study compared neuromuscular activation, measured by surface electromyography (EMG) amplitude [measure by EMG peak (EMGPEAK)] and range of motion (ROM) where EMGPEAK occurred between two training protocols, matched by time under tension, but with a different number and duration of repetitions. Sixteen recreationally trained males performed 2 training protocols with 3 sets, 180 s of rest with 60% of one-repetition maximum(1RM) on the bench press performed in a Smith machine. Protocol A consisted of 6 repetitions with a repetition duration of 6 s and protocol B consisted of 12 repetitions with a repetition duration of 3 s. EMG activity of anterior deltoid, pectoralis major and triceps brachii muscles were recorded. The results showed a general higher EMG amplitude (regardless of the muscle) in protocol B (p = 0.010), and pectoral and triceps brachii consistently presented higher neuromuscular activation than anterior deltoid at both protocols (p = 0.007). Additionally, the ROM where EMGPEAK occurred in triceps brachii was in the middle of the concentric action (~50% of ROM), this occurred in the first half of the same action (~24% of ROM) in the other muscles. In conclusion, protocol B demonstrated an increased EMG amplitude over protocol A, although both protocols responded similarly by achieving the highest EMG amplitude at same ROM among the muscles analysed.
       
  • Relationships between the foot posture Index and static as well as dynamic
           rear foot and arch variables
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Anja-Verena Behling, Benno Maurus NiggAbstractClinicians, podiatrists and researchers have been quantifying foot posture and movement in various speed conditions and populations. Common variables to assess foot posture/movement are the Foot Posture Index (FPI-6), Achilles tendon angle (β), rear foot angle (γ) and longitudinal arch angle (LAA). These variables were frequently used in clinical and biomechanical settings. This study aimed to determine the relationship between the biomechanical variables (β, γ & LAA) in static and dynamic conditions and the clinically used FPI-6 and their redundancy.Forty participants performed bipedal standing, over ground walking and running trials. Manual assessment data (FPI-6), kinematic data and ground reaction forces were collected. Discrete biomechanical variables (β, γ & LAA) were calculated at various time points (e.g. heel strike). A Principal Component Analysis (PCA) was performed to quantify the contribution of each variable to the overall variance in the data set. Spearman correlations were used to assess the relationship between the sub-measures of the FPI-6 and the biomechanical variables.Two major components were found that explained 85.2% of the overall variance, consisting of LAA and β variables, respectively. Only LAA variables showed significant, but moderate correlations (r 
       
  • Anterior cruciate ligament transection of rabbits alters composition,
           structure and biomechanics of articular cartilage and chondrocyte
           deformation 2 weeks post-surgery in a site-specific manner
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Simo P. Ojanen, Mikko A.J. Finnilä, Janne T.A. Mäkelä, Kiira Saarela, Emilia Happonen, Walter Herzog, Simo Saarakkala, Rami K. KorhonenAbstractAnterior cruciate ligament (ACL) injury often leads to post-traumatic osteoarthritis (OA) and articular cartilage degradation, changing biomechanics of the tissue and chondrocytes, and altering the fixed charged density (FCD) and collagen network. However, changes in these properties are not known at a very early time point after ACL rupture, but recognizing early changes might be crucial for successful intervention. We investigated the effects of ACL transection (ACLT) in rabbits on the site-specific biomechanical properties of articular cartilage and chondrocytes, FCD content and collagen network organization, two weeks post-surgery.Unilateral ACLT was performed in eight rabbits, and femoral condyles, tibial plateaus, femoral grooves and patellae were harvested from experimental and contralateral knee joints. An intact control group was used as a reference. We analyzed chondrocyte morphology under pre- and static loading, cartilage biomechanical properties, FCD content and collagen fibril orientation.ACLT caused FCD loss in the lateral and medial femoral condyle, lateral tibial plateau, femoral groove and patellar cartilage (p 
       
  • Implementation of physiological functional spinal units in a rigid-body
           model of the thoracolumbar spine
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Wei Wang, Dongmei Wang, Friedl De Groote, Lennart Scheys, Ilse JonkersAbstractMost of the current rigid-body models of the complete thoracolumbar spine do not properly model the intervertebral joint as the highly nonlinear stiffness is not incorporated comprehensively and the effects of compressive load on stiffness is commonly being neglected. Based on published in vitro data of individual intervertebral joint flexibility, multi-level six degree-of-freedom nonlinear stiffness of functional spinal units was modelled and incorporated in a rigid-body model of the thoracolumbar spine. To estimate physiological in vivo conditions of the entire spine, stiffening effects caused by directly applied compressive loads, and contributions to mono-segmental stiffness from the rib cage as well as multi-segmental interactions in the thoracic spine were analysed and implemented. Forward dynamic simulations were performed to simulate in vitro tests that measured the load-displacement response of the spine under various loading conditions. The predicted kinematic responses of the model were in agreement with in vitro measurements, with correlations between simulated and measured segmental displacements varying between 0.66 and 0.97 (p 
       
  • Inflation experiments and inverse finite element modelling of posterior
           human sclera
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Brendan Geraghty, Ahmed Abass, Ashkan Eliasy, Stephen W. Jones, Paolo Rama, Wael Kassem, Riaz Akhtar, Ahmed ElsheikhAbstractThe complexity of inverse finite element modelling methods used in ocular biomechanics research has significantly increased in recent years in order to produce material parameters that capture microscale tissue behaviour. This study presents a more accessible method for researchers to optimise sclera material parameters for use in finite element studies where macroscale sclera displacements are required.Five human donor sclerae aged between 36 and 72 years were subjected to cycles of internal pressure up to 61 mmHg using a custom-built inflation rig. Displacements were measured using a laser beam and two cameras through a digital image correlation algorithm. Specimen-specific finite element models incorporating regional thickness variation and sclera surface topography were divided into six circumferential regions. An inverse finite element procedure was used to optimise Ogden material parameters for each region.The maximum root mean squared (RMS) error between the numerical and experimental displacements within individual specimens was 17.5 µm. The optimised material parameters indicate a gradual reduction in material stiffness (as measured by the tangent modulus) from the equator to the posterior region at low-stress levels up to 0.005 MPa. The variation in stiffness between adjacent regions became gradually less apparent and statistically insignificant at higher stresses.The study demonstrated how inflation testing combined with inverse modelling could be used to effectively characterise regional material properties capable of reproducing global sclera displacements. The material properties were found to vary between specimens, and it is expected that age could be a contributing factor behind this variation.
       
  • In vivo attachment site to attachment site length and strain of the ACL
           and its bundles during the full gait cycle measured by MRI and high-speed
           biplanar radiography
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Zoë A. Englander, William E. Garrett, Charles E. Spritzer, Louis E. DeFrateAbstractThe purpose of this study was to measure in vivo attachment site to attachment site lengths and strains of the anterior cruciate ligament (ACL) and its bundles throughout a full cycle of treadmill gait. To obtain these measurements, models of the femur, tibia, and associated ACL attachment sites were created from magnetic resonance (MR) images in 10 healthy subjects. ACL attachment sites were subdivided into anteromedial (AM) and posterolateral (PL) bundles. High-speed biplanar radiographs were obtained as subjects ambulated at 1 m/s. The bone models were registered to the radiographs, thereby reproducing the in vivo positions of the bones and ACL attachment sites throughout gait. The lengths of the ACL and both bundles were estimated as straight line distances between attachment sites for each knee position. Increased attachment to attachment ACL length and strain were observed during midstance (length = 28.5 ± 2.6 mm, strain = 5 ± 4%, mean ± standard deviation), and heel strike (length = 30.5 ± 3.0 mm, strain = 12 ± 5%) when the knee was positioned at low flexion angles. Significant inverse correlations were observed between mean attachment to attachment ACL lengths and flexion (rho = −0.87, p 
       
  • The use of the gait profile score and gait variable score in individuals
           with Duchenne Muscular Dystrophy
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Mariana Angélica de Souza, Ananda Cezarani, Elisangela Aparecida da Silva Lizzi, Gabriela Barroso de Queiroz Davoli, Stela Márcia Mattiello, Richard Jones, Ana Cláudia Mattiello-SverzutAbstractTherapeutic gait interventions for individuals with Duchenne Muscular Dystrophy (DMD) should be based on understanding how movement of the individual is affected and whether different clusters of individuals, determined by clinical severity, differ. Gait indexes have been developed to synthesize the data provided by the three-dimensional (3D) gait analysis such as the Gait Deviation Index (GDI) and the Gait Profile Score (GPS) where the gait variable score (GVS) can be calculated. The objective this study was to evaluate the potential use of the GDI and GPS and MAP using data from 3D gait analysis of DMD patients. The dimension 1 score of the Motor Function Measurement defined the groups that composed the cluster analysis. Twenty patients with DMD composed 2 groups according to the cluster analysis (Cluster 1, n = 10; Cluster 2, n = 10). Three-dimensional gait analysis was conducted where GDI, GPS and GVS (pelvic tilt/obliquity; hip flexion-extension/adduction-abduction/rotation; knee flexion-extension; ankle dorsiflexion-plantarflexion, foot progression angle) were calculated. Cluster 1 group presented lower hip flexion-extension and lower pelvic obliquity when compared with Cluster 2 group (p  0.05). This study showed that GVS could detect alterations on the parameters obtained using three-dimensional gait analysis for those DMD patients separated according to motor function regarding pelvic and hip kinematic patterns. The rehabilitation of patients with DMD is recommended from the early stages of the disease (as Cluster 1, with>MFM) with the hip joint being the therapeutic target.
       
  • Age-associated changes in the mechanical properties of human cadaveric
           pelvic floor muscles
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Lindsey A. Burnett, Mark Cook, Sameer Shah, Ms. Michelle Wong, Deborah M. Kado, Marianna AlperinAbstractProper function of the female pelvic floor requires intact pelvic floor muscles (PFMs). The prevalence of pelvic floor disorders (PFDs) increases substantially with age, in part due to clinically identified deterioration of PFM function with age. However, the etiology of this decline remains largely unknown. We previously demonstrated that PFMs undergo age-related fibrotic changes. This study sought to determine whether aging also impacts PFMs’ passive mechanical properties that are largely determined by the intramuscular extracellular matrix. Biopsies from younger (≤52y) and older (>52y) female cadaveric donors were procured from PFMs, specifically coccygeus (C) and two portions of the levator ani - iliococcygeus (IC) and pubovisceralis (PV), and the appendicular muscles - obturator internus (OI) and vastus lateralis (VL). Muscle bundles were subjected to a passive loading protocol, and stress-sarcomere length (Ls) relationships calculated. Muscle stiffness was compared between groups using 2-way ANOVA and Sidak pairwise comparisons, α 
       
  • How age and surface inclination affect joint moment strategies to
           accelerate and decelerate individual leg joints during walking
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Jeroen B. Waanders, Alessio Murgia, Tibor Hortobágyi, Paul DeVita, Jason R. FranzAbstractA joint moment also causes motion at other joints of the body. This joint coupling-perspective allows more insight into two age-related phenomena during gait. First, whether increased hip kinetic output compensates for decreased ankle kinetic output during positive joint work. Second, whether preserved joint kinetic patterns during negative joint work in older age have any functional implication. Therefore, we examined how age and surface inclination affect joint moment strategies to accelerate and/or decelerate individual leg joints during walking. Healthy young (age: 22.5 ± 4.1 years, n = 18) and older (age: 76.0 ± 5.7 years, n = 22) adults walked at 1.4 m/s on a split-belt instrumented treadmill at three grades (0%, 10%, −10%). Lower-extremity moment-induced angular accelerations were calculated for the hip (0% and 10%) and knee (0% and −10%) joints. During level and uphill walking, both age groups showed comparable ankle moment-induced ipsilateral (p = 0.774) and contralateral (p = 0.047) hip accelerations, although older adults generated lower ankle moments in late stance. However, ankle moment-induced contralateral hip accelerations were smaller (p = 0.001) in an older adult subgroup (n = 13) who showed larger hip extension moments in early stance than young adults. During level and downhill walking, leg joint moment-induced knee accelerations were unaffected by age (all p > 0.05). These findings suggest that during level and uphill walking increased hip flexor mechanical output in older adults does not arise from reduced ankle moments, contrary to increased hip extensor mechanical output. Additionally, results during level and downhill walking imply that preserved eccentric knee extensor function is important in maintaining knee stabilization in older age.
       
  • Validating diverse human body models against side impact tests with
           post-mortem human subjects
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Eunjoo Hwang, Jingwen Hu, Matthew P. ReedAbstractThis study aimed at evaluating the ability of morphed finite element (FE) human body models (HBMs) to reproduce the impact responses of post-mortem human subjects (PMHS) with various stature and shape. Ten side impact tests previously performed using seven PMHS under 3 m/s and 8 m/s impact velocities were selected for model evaluation. With weight, stature, sex, and age of PMHS, seven FE HBMs were developed by morphing the midsize male THUMS model into the target geometries predicted by the statistical skeleton and external body shape models. The model-predicted force histories, accelerations along the spine, and deflections in the chest and abdomen were compared to the test data. For comparison, simulations in all testing conditions were also conducted with the original midsize male THUMS, and the results from the THUMS simulations were scaled to the weight and stature from each PMHS. The CORrelation and Analysis (CORA) was used to evaluate the model accuracy, with CORA scores close to one indicating excellent agreement. Ten simulations using the morphed models exhibited 0.80 ± 0.01, 0.80 ± 0.01, 0.78 ± 0.02, and 0.78 ± 0.02 CORA scores for the impact forces to the thorax, abdomen, iliac-wings, and greater-trochanter, respectively; the corresponding CORA scores with the original THUMS were markedly lower at 0.60 ± 0.06, 0.69 ± 0.05, 0.71 ± 0.05, and 0.69 ± 0.04; while those for the scaled THUMS were 0.65 ± 0.05, 0.71 ± 0.05, 0.73 ± 0.05, and 0.72 ± 0.02, also lower than the morphed models. Across all simulations, the morphed HBMs demonstrated significantly higher accuracy than the THUMS with or without scaling. These results suggested the necessity of accounting for size and shape effects on predicting human responses in side impacts.
       
  • Intervertebral range of motion characteristics of normal cervical spinal
           segments (C0-T1) during in vivo neck motions
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Chaochao Zhou, Haiming Wang, Cong Wang, Tsung-Yuan Tsai, Yan Yu, Peter Ostergaard, Guoan Li, Thomas ChaAbstractThe in vivo intervertebral range of motion (ROM) is an important predictor for spinal disorders. While the subaxial cervical spine has been extensively studied, the motion characteristics of the occipito-atlantal (C0-1) and atlanto-axial (C1-2) cervical segments were less reported due to technical difficulties in accurate imaging of these two segments. In this study, we investigated the intervertebral ROMs of the entire cervical spine (C0-T1) during in vivo functional neck motions of asymptomatic human subjects, including maximal flexion-extension, left-right lateral bending, and left-right axial torsion, using previously validated dual fluoroscopic imaging and model registration techniques. During all neck motions, C0-1, similar to C7-T1, was substantially less mobile than other segments and always contributed less than 10% of the cervical rotations. During the axial rotation of the neck, C1-2 contributed 73.2 ± 17.3% of the cervical rotation, but each of other segments contributed less than 10% of the cervical rotation. During both lateral bending and axial torsion neck motions, regardless of primary or coupled motions, the axial torsion ROM of C1-2 was significantly greater than its lateral bending ROM (p 
       
  • Influence of osmolarity and hydration on the tear resistance of the human
           amniotic membrane
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Kevin Bircher, Riccardo Merluzzi, Adam Wahlsten, Deborah Spiess, Ana Paula Simões-Wüst, Nicole Ochsenbein-Kölble, Roland Zimmermann, Jan Deprest, Edoardo MazzaAbstractThe amnion is considered to be the load-bearing part of the fetal membranes. We investigated the influence of osmolarity of the testing medium and hydration on its fracture toughness. Mode I fracture tests revealed that physiological variations in the bath osmolarity do not influence the tear resistance of amnion, while larger changes, i.e. from physiological saline solution to distilled water, lead to a significant reduction of the fracture toughness. Uniaxial tensile tests on collagen hydrogels confirmed the reduction in toughness, suggesting that lower bath osmolarity triggers changes in the failure properties of single collagen fibers. Prenatal surgeries, in particular fetoscopic procedures with partial amniotic carbon dioxide insufflation, might result in dehydration of the amnion. Dehydration induced a brittle behavior; however, subsequent rehydration for 15 min resulted in a similar tear resistance as for the fresh tissue.
       
  • Estimating the stabilizing function of ankle and subtalar ligaments via a
           morphology-specific three-dimensional dynamic model
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Emanuele Palazzi, Sorin Siegler, Vishnuvardhan Balakrishnan, Alberto Leardini, Paolo Caravaggi, Claudio BelvedereAbstractKnowledge of the stabilizing role of the ankle and subtalar ligaments is important for improving clinical techniques such as ligament repair and reconstruction. However, this knowledge is incomplete. The goal of this study was to expand this knowledge by investigating the stabilizing function of the ligaments using multiple morphologically subject-specific computational models.Nine models were created from the lower extremities of nine donors. Each model consisted of the articulating bones, articular cartilage, and ligaments. Simulations were conducted in ADAMS™ – a dynamic simulation program. During simulation, tibia and fibula were fixed while cyclic moments in all three anatomical planes were applied to the calcaneus one-at-a-time. The resulting displacements between the bones and the forces in each ligament were computed. Simulations were conducted with all ligaments intact and after simulated ligament serial sectioning. Each model was validated by comparing the simulation results to experimental data obtained from the specimen used to construct the model. From the results the stabilizing role of each ligament was established and the effect of ligament sectioning on Range of Motion and Overall Laxity was identified.On the lateral side, ATFL provided stabilization in supination, CFL restrained inversion, external rotation and dorsiflexion and PTFL limited dorsiflexion and external rotation. On the medial side, PTTL restrained dorsiflexion and internal rotation, ATTL limited plantarflexion and external rotation, and TCL limited dorsiflexion, eversion and external rotation. At the subtalar joint, ITCL limited plantarflexion and its posterior-lateral bundle restrained subtalar inversion. CL restrained plantarflexion/dorsiflexion, and internal and external rotation.The large inter-model variability observed in the results indicate the importance of using multiple subject-specific models rather than relying on one “representative” model.
       
  • Stepping over multiple obstacles changes the pattern of foot integrated
           pressure of the leading and trailing legs
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Zhuo Wang, Jung Hung Chien, Ka-Chun SiuAbstractAn efficient obstacle avoidance strategy when stepping over a single obstacle was reported in the literature – the total impulse of the leading and of the trailing legs are equal even though the kinematics parameters of two legs are different. However, does this efficient obstacle avoidance strategy exist when stepping over multiple obstacles' The study attempted to answer this question. Nineteen healthy young adults (25.84 ± 3.35 years) were recruited and performed multiple obstacle crossings when intervals between two obstacles were one-step, two-step, and three-step away, respectively. The dependent variables were foot integrated pressure (FIP) and other kinematic parameters – horizontal distance (HD, a heel-contact-to-obstacle distance of the leading leg/toe-off-to-obstacle distance of the trailing leg) and vertical distance (VD, toe clearance of both legs). A significant interaction among the effect of different legs, different intervals, and different obstacles on FIP, and kinematic parameters of HD and VD was found (p 
       
  • Micromotion at the head-stem taper junction of total hip prostheses is
           influenced by prosthesis design-, patient- and surgeon-related factors
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Adrian Falkenberg, Sara Biller, Michael M. Morlock, Gerd HuberAbstractTaper junctions of modular hip prostheses are susceptible to fretting and crevice corrosion. Prevalence and significance increase for cobalt-chromium heads assembled on titanium-alloy stems. Retrieval and in-vitro studies have identified micromotion between the taper components to accelerate the corrosion process. The aim of this study was to identify the most critical factors contributing to increased micromotion, which is most likely influenced by design-, patient- and surgeon-related aspects. Micromotion between head and stem taper surfaces was measured for different taper surface topographies and load orientations. Consecutive visual images were recorded through windows in the head component. By image matching analysis the local micromotions at the taper junction between head and stem tapers were determined. To extend the findings to taper regions not visible through the windows, finite element models were generated. The models were further utilized to investigate the influence of head length, taper angle difference and assembly force on micromotion. Significantly higher micromotion (+20%) was found under varus loading (7.1 µm) in comparison to valgus loading (5.9 µm). Smooth and microgrooved stem tapers exhibited equal amounts of micromotion. The numerical model revealed head tilting and recurring taper contact changes in terms of cyclic engagement/disengagement during the loading sequences. Especially long heads (+240%) and low assembly forces (+53%) were found to substantially increase micromotion (from 2.7 µm to 9.3 µm and from 4.1 µm to 8.8 µm, respectively). This study accentuates the susceptibility of taper junctions to a variety of factors, which need to be appreciated in preoperative planning and surgical procedure to reduce the amount of micromotion and such minimize the risk of critical corrosion.
       
  • The influence of hemodynamics on graft patency prediction model based on
           support vector machine
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Boyan Mao, Yue Feng, Wenxin Wang, Bao Li, Zhou Zhao, Xiaoyan Zhang, Chunbo Jin, Dandan Wu, Youjun LiuAbstractIn the existing patency prediction model of coronary artery bypass grafting (CABG), the characteristics are based on graft flow, but no researchers selected hemodynamic factors as the characteristics. The purpose of this paper is to study whether the introduction of hemodynamic factors will affect the performance of the prediction model.Transit time flow-meter (TTFM) waveforms and 1-year postoperative patency results were obtained from 50 internal mammary arterial grafts (LIMA) and 82 saphenous venous grafts (SVG) in 60 patients. Taking TTFM waveforms as the boundary conditions, the CABG ideal models were constructed to obtain hemodynamic factors in grafts. Based on clinical characteristics and combination of clinical and hemodynamic characteristics, patency prediction models based on support vector machine (SVM) were constructed respectively.For LIMA, after the introduction of hemodynamic factors, the accuracy, sensitivity and specificity of the prediction model increased from 70.35%, 50% and 74.17% to 78.02%, 70% and 78.89%, respectively. For SVG, the accuracy, sensitivity and specificity of the prediction model increased from 63.24%, 40% and 76.91% to 74.41%, 60.1% and 82.73%, respectively.The performance of the prediction model can be improved by introducing hemodynamic factors into the characteristics of the model. The accuracy, sensitivity and specificity of the prediction results are higher with the addition of hemodynamic characteristics.
       
  • A new deep learning-based method for the detection of gait events in
           children with gait disorders: Proof-of-concept and concurrent validity
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Mathieu Lempereur, François Rousseau, Olivier Rémy-Néris, Christelle Pons, Laetitia Houx, Gwenolé Quellec, Sylvain BrochardAbstractThe stance and swing phases of the gait cycle are defined by foot strike (FS) and foot off (FO). Accurate determination of these events is thus an essential component of 3D motion recordings processing. Several methods have been developed for the automatic detection of these events (based on the heuristics of 3D marker position, velocity and acceleration), however the results may be inaccurate due to the high variability that is intrinsic to pathological gait. For this reason, gait events are still commonly determined manually, which is a tedious process. Here we propose a new application (DeepEvent) of a long short term memory recurrent neural network for the automatic detection of gait events. The 3D position and velocity of the markers on the heel, toe and lateral malleolus were used by the network to determine FS and FO. The method was developed from 10526 FS and 9375 FO from 226 children. DeepEvent predicted FS within 5.5 ms and FO within 10.7 ms of the gold standard (automatic determination using force platform data) and was more accurate than common heuristic marker trajectory-based methods proposed in the literature and another deep learning method.A sensitivity analysis showed that DeepEvent mainly used the toe and heel markers (z-axis (longitudinal) position and velocity) at the beginning and end of gait cycle to predict FS, and the toe marker (x-axis (anterior/posterior) velocity and z-axis position and velocity) at around 60% of the gait cycle to predict FO.
       
  • Non-rigid alignment pipeline applied to human gait signals acquired with
           optical motion capture systems and inertial sensors
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Rubén Soussé, Jorge Verdú, Ricardo Jauregui, Ventura Ferrer-Roca, Simone BaloccoAbstractAn accurate gait characterization is fundamental for diagnosis and treatment in both clinical and sportive fields. Although several devices allow such measurements, the performance comparison between the acquired signals may be a challenging task.A novel pipeline for the accurate non-rigid alignment of gait signals is proposed. In this paper, the measurements of Inertial Measurement Units (IMU) and Optical Motion Capture Systems (OMCAP) are aligned using a modified version of the Dynamic Time Warping (DTW) algorithm. The differences between the two acquisitions are evaluated using both global (RMSE, Correlation Coefficient (CC)) and local (Statistical Parametric Mapping (SPM)) metrics.The method is applied to a data-set obtained measuring the gait of ten healthy subjects walking on a treadmill at three different gait paces. Results show a global bias between the signal acquisition of 0.05°.Regarding the global metrics, a mean RMSE value of 2.65° (0.73°) and an average CC value of 0.99 (0.01) were obtained. The SPM profile shows, in each gait cycle phase, the percentage of cases when two curves are statistically identical and reaches an average of 48% (22%).
       
  • Biomechanical effects of passive hip springs during walking
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Florian L. Haufe, Peter Wolf, Robert Riener, Martin GrimmerAbstractPassive spring-like structures can store and return energy during cyclic movements and thereby reduce the energetic cost of locomotion. That makes them important components of the human body and wearable assistive devices alike. This study investigates how springs placed anteriorly across the hip joint affect leg joint angles and powers, and leg muscle activities during level walking at 0.5 to 2.1 m/s.We hypothesized that the anterior hip springs (I) load hip extension, (II) support hip flexion and (III) affect ankle muscle activity and dynamics during walking. Effects at the ankle were expected because hip and ankle redistribute segmental power in concert to achieve forward progression.We observed that the participants’ contribution to hip power did not increase during hip extension as the spring stored energy. Simultaneously, the activities of plantarflexor muscles that modulate energy storage in the Achilles tendon were reduced by 28% (gastrocnemius medialis) and 9% (soleus). As the spring returned energy with the onset of hip flexion, the participants’ contribution to hip power was reduced by as much as 23%. Soleus activity before push-off increased by up to 9%.Instead of loading hip extension, anterior hip springs seem to store and return parts of the energy normally exchanged with the Achilles tendon. Thereby, the springs support hip flexion but may reduce elastic energy storage in and hence recoil from the Achilles tendon. This interaction should be considered during the design and simulation of wearable assistive devices as it might – depending on user characteristics – enhance or diminish their overall functionality.
       
  • A comprehensive study on the mechanical properties of different regions of
           8-week-old pediatric porcine brain under tension, shear, and compression
           at various strain rates
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Zhigang Li, Cheng Ji, Dapeng Li, Rutao Luo, Guangliang Wang, Jinzhong JiangAbstractYoung porcine brain is often used as a surrogate for studying the mechanical factors affecting traumatic brain injury in children. However, the mechanical properties of pediatric brain tissue derived from humans and piglets are very scarce, and this seriously detracts from the biofidelity of the developed finite element (FE) models of the pediatric head/brain. The present study addresses this issue by subjecting the cerebrum (white matter and gray matter), cerebellum, and brainstem specimens derived from 8-week-old piglets to tension and shear testing at strain rates of 0.01, 1, and 50/s. The experimental data are combined with the corresponding data derived from a previous study under compression to obtain comprehensive stress-strain curves of the pediatric porcine cerebrum, cerebellum, and brainstem tissue specimens. In general, the average stress level of the white matter is somewhat higher than that of the gray matter under the tension, shear and compression conditions, however, this difference does not reach a significant level. The stiffness of the cerebellum and the cerebrum does not differ significantly under tension and shear conditions, but the stiffness of the cerebellum is greater than that of the cerebrum under compression. The brainstem has significantly higher stiffness than the cerebrum and the cerebellum under all loading modes. In addition, the mechanical properties of brain tissue exhibit significant strain-rate dependences. With increasing strain rate from 0.01/s to 50/s, the average stress at a strain of 0.5 for all of the brain tissue increased by about 2.2 times under tension, about 2.4 times under shearing and about 2.2 times under compression. The variations in the stress as a function of the strain rate for brain tissue specimens were well characterized by exponential functions at strains of 0.25 and 0.5 under all three loading modes. The results of this study are useful for developing biofidelic FE models of the pediatric brain.
       
  • Comparison of the rigidity and forefoot – Rearfoot kinematics from three
           forefoot tracking marker clusters during walking and weight-bearing foot
           pronation-supination
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Fabrício Anicio Magalhães, Thales Rezende Souza, Vanessa Lara Araújo, Lílian Marques Oliveira, Letícia de Paula Silveira, Juliana de Melo Ocarino, Sérgio Teixeira FonsecaAbstractDue to the relative motion among the foot rays, the present study aimed to compare the rigidity as well as the forefoot – rearfoot kinematics obtained from three forefoot tracking marker clusters during walking and foot pronation-supination (PROSUP). Nineteen healthy adults performed six walking trials and ten cycles of foot PROSUP movements recorded by an optoelectronic system. Rearfoot's and forefoot's coordinate system were equal for all setups, only the forefoot's tracking markers locations varied among them, which were: (1st) a typical cluster, focusing on the proximal forefoot, (2nd) a second typical cluster, focusing on the distal forefoot and outer metatarsals, and (3rd) a new cluster proposition, focusing on the distal forefoot and central metatarsals. Cluster rigidity was the normalized intra-markers residual, and forefoot – rearfoot angles were the forefoot motion relative to the rearfoot at the peak of each plane of motion. Repeated-measures ANOVA with pairwise comparisons (α=0.05) revealed that the 3rd cluster had the smallest residual (p 
       
  • A more compliant prosthetic foot better accommodates added load while
           walking among Servicemembers with transtibial limb loss
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Barri L. Schnall, Christopher L. Dearth, Jonathan M. Elrod, Pawel R. Golyski, Sara R. Koehler-McNicholas, Samuel F. Ray, Andrew H. Hansen, Brad D. HendershotAbstractSelecting an optimal prosthetic foot is particularly challenging for highly active individuals with limb loss, such as military personnel, who need to seamlessly perform a variety of demanding activities/tasks (often with and without external loads) while minimizing risk of musculoskeletal injuries over the longer term. Here, we expand on prior work by comparing biomechanical and functional outcomes in two prosthetic feet with the largest differences in mechanical response to added load (i.e., consistently “Compliant” and “Stiff” forefoot properties). In each foot, fourteen male Servicemembers with unilateral transtibial limb loss (from trauma) completed instrumented gait analyses in all combinations of two loading conditions (with and without 22 kg weighted vest) and two walking speeds (1.34 and 1.52 m/s), as well as the Prosthesis Evaluation Questionnaire. With the Stiff foot, sound limb peak loading was 2% smaller (p = 0.043) in the loaded versus unloaded condition, but similar between loading conditions in the Compliant foot (note, the Stiff foot was associated with larger loads, overall). Independent of load or walking speed, the Compliant (versus Stiff) foot provided 67.9% larger (p 
       
  • The feasibility of a split-belt instrumented treadmill running protocol
           with perturbations
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Andrew Quarmby, Mina Khajooei, Tilman Engel, Hannes Kaplick, Frank MayerAbstractUnexpected perturbations during locomotion can occur during daily life or sports performance. Adequate compensation for such perturbations is crucial in maintaining effective postural control. Studies utilising instrumented treadmills have previously validated perturbed walking protocols, however responses to perturbed running protocols remain less investigated. Therefore, the purpose of this study was to investigate the feasibility of a new instrumented treadmill-perturbed running protocol.Fifteen participants (age = 28 ± 3 years; height = 172 ± 9 cm; weight = 69 ± 10 kg; 60% female) completed an 8-minute running protocol at baseline velocity of 2.5 m/s (9 km/h), whilst 15 one-sided belt perturbations were applied (pre-set perturbation characteristics: 150 ms delay (post-heel contact); 2.0 m/s amplitude; 100 ms duration). Perturbation characteristics and EMG responses were recorded. Bland-Altman analysis (BLA) was employed (bias ± limits of agreement (LOA; bias ± 1.96*SD)) and intra-individual variability of repeated perturbations was assessed via Coefficients of Variation (CV) (mean ± SD).On average, 9.4 ± 2.2 of 15 intended perturbations were successful. Perturbation delay was 143 ± 10 ms, amplitude was 1.7 ± 0.2 m/s and duration was 69 ± 10 ms. BLA showed −7 ± 13 ms for delay, −0.3 ± 0.1 m/s for amplitude and −30 ± 10 ms for duration. CV showed variability of 19 ± 4.5% for delay, 58 ± 12% for amplitude and 30 ± 7% for duration. EMG RMS amplitudes of the legs and trunk ranged from 113 ± 25% to 332 ± 305% when compared to unperturbed gait. This study showed that the application of sudden perturbations during running can be achieved, though with increased variability across individuals. The perturbations with the above characteristics appear to have elicited a neuromuscular response during running.
       
  • Short Communication: Determining the average attitude of a rigid
           body
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): John H. ChallisAbstractThree-dimensional angular kinematics exist on the surface of a unit hypersphere, therefore the average attitude cannot always be accurately computed by averaging Cardan angles. This study derives and evaluates a method for determining average body attitude, by exploiting the singular value decomposition of the average of a set of attitude matrices. To test the method 1000 criterion attitudes were determined, and for each attitude 10 noisy attitude matrices generated. The new method and the averaging of Cardan angles extracted from the 10 noisy attitude matrices were evaluated for their ability to estimate the criterion attitude. At low attitude variance the two approaches provided equivalent results, but with increasing attitude variance levels the new procedure was superior. The method provides superior estimates of average attitude compared with averaging Cardan angles, by accounting for the geometric distribution of rigid body attitudes on the surface of a unit hypersphere.
       
  • The effects of −80 °C short-term storage on the mechanical response
           of tricuspid valve leaflets
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Samuel D. Salinas, Margaret M. Clark, Rouzbeh AminiAbstractMechanical testing of soft tissues would ideally rely on using fresh specimens. In the event that fresh tissues are not readily available, alternative measures, such as storing fresh specimens at −80 °C, could be considered. Previous studies have shown that changes in the mechanical properties of the tissues due to freezing could be tissue-dependent. Prior to our study, however, such information was not available for the tricuspid valve leaflets. As such, for the first time, we examined whether fresh porcine specimens tested in a biaxial tensile machine would offer comparable results after being frozen at −80 °C. The stress-strain response of the tricuspid valve leaflets displayed no major deviation of the post-frozen leaflets as compared to fresh leaflets. We further compared the radial and circumferential strains as an indicator of deformation at similar stress states in fresh and thawed tissues, and we did not find any significant differences. Ice formation within the extra cellular matrix may modify the collagen fiber configuration, resulting in a slight change in the mechanical response. Nevertheless, our results indicated such a small deviation was negligible, thus enabling the possibility of using frozen porcine tricuspid valve specimens for future research.
       
  • 3D printed clamps improve spine specimen fixation in biomechanical testing
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Frédéric Cornaz, Marie-Rosa Fasser, José Miguel Spirig, Jess G. Snedeker, Mazda Farshad, Jonas WidmerAbstractThis study presents an anatomically customizable fixation technique for biomechanical spine experiments using a 3D printed clamping system. The aim of this study is to evaluate the feasibility and compare the fixation rigidity of the novel technique to PMMA potting with and without screw augmentation. For this purpose, 16 thoracic and lumbar functional spine units of bovine, porcine, ovine and human cadavers (4 each) were consecutively fixed with all three techniques and loaded in six degrees of freedom. The combined relative movement between the cranial and caudal vertebral body and their corresponding fixtures were recorded using a 3D motion capture system. The 3D printed clamps did provide multiple advantages, showed no failures and the fixation rigidity was superior to potting in all loading directions and superior to screw-augmented potting in two of six loading directions (p 
       
  • Validation of a custom spine biomechanics simulator: A case for
           standardization
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): John T. Sherrill, Safeer F. Siddicky, Wyatt D. Davis, Caroline Chen, David B. Bumpass, Erin M. MannenAbstractMechanical testing machines used in cadaveric spine biomechanics research vary between labs. It is a necessary first step to understand the capabilities and limitations in any testing machine prior to publishing experimental data. In this study, a reproducible protocol that uses a synthetic spine was developed and used to quantify the inherent rotation error and the ability to apply loads in a single physiologic plane (pure-moment) of a custom spine biomechanics simulator. Rotation error was evaluated by comparing data collected by the test machine and the data collected by an optical motion capture system. Pure-moment loading was assessed by comparing the out-of-plane loads to the primary plane load. Using synthetic functional spine units previously shown to have mechanics similar to the cadaveric human spine, the simulator was evaluated using a dynamic test protocol reflective of its future use in the study of cadaveric spine specimens. Rotation errors inherent in the test machine were
       
  • An ex vivo technique for quantifying mouse lung injury using ultrasound
           surface wave elastography
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Boran Zhou, Kyle J. Schaefbauer, Ashley M. Egan, Eva M. Carmona Porquera, Andrew H. Limper, Xiaoming ZhangAbstractIdiopathic pulmonary fibrosis is a progressively fatal disease with limited treatments. The bleomycin mouse model is often used to simulate the disease process in laboratory studies. The aim of this study was to develop an ex vivo technique for assessing mice lung injury using lung ultrasound surface wave elastography (LUSWE) in the bleomycin mouse model. The surface wave speeds were measured at three frequencies of 100, 200, and 300 Hz for mice lungs from control, mild, and severe groups. The results showed significant differences in the lung surface wave speeds, pulse oximetry, and compliance between control mice and mice with severe pulmonary fibrosis. LUSWE is an evolving technique for evaluating lung stiffness and may be useful for assessing pulmonary fibrosis in the bleomycin mouse model.
       
  • Ultrasound shear wave elastography for measuring intracompartmental
           pressure of compartment syndrome using a turkey hind limb model
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Yoichi Toyoshima, Jeremy Webb, Adriana Gregory, Mostafa Fatemi, Azra Alizad, Chunfeng ZhaoAbstractDiagnosis and treatment of acute compartment syndrome are quite challenging. It is well known that compartment pressure is an important factor for diagnosing fasciotomy. However, the current technology to measure the pressure using a needle-catheter is invasive and painful. Recently ultrasound elastography has been used to measure soft tissue elasticity based on shear wave propagation speed. Because the muscle’s elasticity is affected by the pressure within the compartment, ultrasound elastography might be a possible tool for the compartment pressure evaluation. Ultrasound shear wave elastography and pressure were simultaneously measured using a clinical ultrasound system and clinically used catheter in a turkey anterior-lateral and anterior-deep compartment under elevated pressures of baseline, 10, 20, 30, 40, and 50 mmHg using vascular infusion technique. Shear wave propagation speed increased linearly in proportion to the increase in intra-compartmental pressure. Strong correlation was observed between measured pressure and mean shear wave speed in each compartment (anterior-lateral compartment, mean R2 = 0.929, P 
       
  • The effects of intensive dietary weight loss and exercise on gait in
           overweight and obese adults with knee osteoarthritis. The Intensive Diet
           and Exercise for Arthritis (IDEA) trial
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Stephen P. Messier, Daniel P. Beavers, Shannon L. Mihalko, Gary D. Miller, Mary F. Lyles, David J. Hunter, J. Jeffery Carr, Felix Eckstein, Ali Guermazi, Richard F. Loeser, Paul DeVitaAbstractThe Intensive Diet and Exercise for Arthritis (IDEA) trial was an 18-month randomized controlled trial that enrolled 454 overweight and obese older adults with symptomatic and radiographic knee osteoarthritis (OA). Participants were randomized to either exercise (E), intensive diet-induced weight loss (D), or intensive diet-induced weight loss plus exercise (D + E) interventions. We previously reported that the clinical benefits of D + E were significantly greater than with either intervention alone (e.g., greater pain reduction, and better function, mobility, and health-related quality of life). We now test the hypothesis that D + E has greater overall benefit on gait mechanics compared to either intervention alone. Knee joint loading was analyzed using inverse dynamics and musculoskeletal modeling. Analysis of covariance determined the interventions’ effects on gait. The D + E group walked significantly faster at 18-month follow-up (1.35 m s−1) than E (1.29 m s−1, p = 0.0004) and D (1.31 m s−1, p = 0.0007). Tibiofemoral compressive impulse was significantly lower (p = 0.0007) in D (1069 N s) and D + E (1054 N s) compared to E (1130 N s). D had significantly lower peak hip external rotation moment (p = 0.01), hip abduction moment (p = 0.0003), and peak hip power production (p = 0.016) compared with E. Peak ankle plantar flexion moment was significantly less (p 10% of baseline body weight had significantly (p = 0.0001) lower resultant knee forces and lower muscle (quadriceps, hamstring, and gastrocnemius) forces than participants that had less weight loss. Compared to E, D produces significant load reductions at the hip, knee, and ankle; combining D with E attenuates these reductions, but most remain significantly better than with E alone.
       
  • Cardiac wall mechanics analysis in hypertension-induced heart failure rats
           with preserved ejection fraction
    • Abstract: Publication date: 2 January 2020Source: Journal of Biomechanics, Volume 98Author(s): Zhongjie Yin, Wenxi Zhang, Dongliang Zhao, Fatiesa Sulejmani, Yundi Feng, Yunlong Huo, Wenchang TanAbstractAlthough cardiac wall mechanics is of importance for understanding heart failure with preserved ejection fraction (HFpEF), there is a lack of relevant mechanics studies. The aim of this study was to analyze the changes in stress and strain in the left ventricle (LV) in hypertension-induced HFpEF rats. Based on experimental measurements in DSS rats fed with high-salt (HS) and low-salt (LS) diets, LV stress and strain were computed throughout the cardiac cycle using Continuity software. HS-feeding increased myofiber stress and strain along both the transmural and longitudinal directions at the end-diastolic state but resulted in a lower absolute value of strain and relatively unchanged stress at the end-systolic state. Moreover, the end-diastolic stress and strain decreased with increasing radial position from the endocardial towards the epicardial walls despite negligible changes along the longitudinal direction. The changes in LV wall mechanics characterized the elevated diastolic LV stiffness and slow LV relaxation in HS-fed rats of HFpEF. These findings denote that a vicious cycle of increased stress and strain and diastolic dysfunction can prompt the development of HFpEF.
       
  • Measuring markers of aging and knee osteoarthritis gait using inertial
           measurement units
    • Abstract: Publication date: Available online 27 December 2019Source: Journal of BiomechanicsAuthor(s): Jocelyn F. Hafer, Seraphina G. Provenzano, Kathy L. Kern, Cristine E. Agresta, John A. Grant, Ronald F. ZernickeAbstractDifferences in gait with age or knee osteoarthritis have been demonstrated in laboratory studies using optical motion capture (MoCap). While MoCap is accurate and reliable, it is impractical for assessment outside the laboratory. Inertial measurement units (IMUs) may be useful in these situations. Before IMUs are used as a surrogate for MoCap, methods that are reliable, repeatable, and that calculate metrics at similar accuracy to MoCap must be demonstrated. The purpose of this study was to compare spatiotemporal gait parameters and knee range of motion calculated via MoCap to IMU-derived variables and to compare the ability of these tools to discriminate between groups. MoCap and IMU data were collected from young, older, and adults with knee osteoarthritis during overground walking at three self-selected speeds. Walking velocity, stride length, cadence, percent of gait cycle in stance, and sagittal knee range of motion were calculated and compared between tools (MoCap and IMU), between participant groups, and across speed. There were no significant differences between MoCap and IMU outcomes, and root mean square error between tools was ≤0.05 m/s for walking velocity, ≤0.07m for stride length, ≤0.5 strides/min for cadence, ≤5% for percent of gait cycle in stance, and ≤1.5° for knee range of motion. No interactions were present, suggesting that MoCap and IMU calculated metrics similarly across groups and speeds. These results demonstrate IMUs can accurately calculate spatiotemporal variables and knee range of motion during gait in young and older, asymptomatic and knee osteoarthritis cohorts.
       
  • Muco-ciliary clearance: A review of modelling techniques
    • Abstract: Publication date: Available online 24 December 2019Source: Journal of BiomechanicsAuthor(s): Shayan M. Vanaki, David Holmes, Suvash Saha, Jinju Chen, Richard J. Brown, Pahala Gedara JayathilakeAbstractThe airways of the human respiratory system are covered by a protective layer, which is known as airway surface liquid (ASL). This layer consists of two relatively distinct sub-layers; a mucus layer (ML), and a periciliary liquid layer (PCL). In addition, the airways are lined with a dense mat of hair-like structures, called cilia, which beat back and forth in a co-ordinated manner and mainly propel the mucus layer. Such interaction between the cilia and mucus is called ‘muco-ciliary clearance’ (MCC) which is essential to clear the respiratory airways from the inhaled toxic particles deposited on the mucus. The complex nature of lung clearance mechanisms limit the ability to conduct experiments to investigate micro-scale physiological phenomena. As such, modelling techniques are commonly implemented to investigate the effects of biological parameters on the lung muco-ciliary clearance.In the present work, modelling techniques of cilia-ASL interactions – including continuum cilia modelling and discrete cilia modelling – are reviewed and the numerical procedures and level of complexity related to each technique are explained. This is followed by a detailed analysis of the airway surface liquid modelling approaches. In addition, findings of numerical investigations related to the effects of various parameters such as ciliary beat frequency (CBF), mucus rheology, metachronal waves of cilia, surface tension at the PCL-mucus interface, ciliary length, ciliary density, and airway surface liquid depth on the bronchial and tracheal ASL transport are reviewed. This review also explains how these biological parameters can alter the internal power required to perform ciliary beating. Lastly, the main limitations of current numerical works are discussed and significant research directions are brought forward that may be considered in future models to better understand this complex human biological system and its vital clearance mechanism.
       
  • Effect on manual skills of wearing instrumented gloves during manipulation
    • Abstract: Publication date: Available online 14 November 2019Source: Journal of BiomechanicsAuthor(s): Alba Roda-Sales, Joaquín L. Sancho-Bru, Margarita Vergara, Verónica Gracia-Ibáñez, Néstor J. Jarque-BouAbstractInstrumented gloves are motion capture systems that are widely used due to the simplicity of the setup required and the absence of occlusion problems when manipulating objects. Nevertheless, the effect of their use on manipulation capabilities has not been studied to date. Therefore, the aim of this work is to quantify the effect of wearing CyberGlove instrumented gloves on these capabilities when different levels of precision are required. Thirty healthy subjects were asked to perform three standardised dexterity tests twice: bare-handed and wearing instrumented gloves. The tests were the Sollerman Hand Function Test (to evaluate capability of performing activities of daily living), the Box and Block Test (to evaluate gross motor skills) and the Purdue Pegboard Test (to evaluate fine motor skills). Scores obtained in the test evaluating fine motor skills decreased by an average of 29% when wearing gloves, while scores obtained on those evaluating gross motor skills and capability to perform activities of daily living were reduced by an average of 8% and 3%, respectively. The use of instrumented gloves to record hand kinematics is only recommended when performing tasks requiring medium and gross motor skills.
       
  • Walking Assistance Using Crutches: A State of the Art Review
    • Abstract: Publication date: Available online 14 November 2019Source: Journal of BiomechanicsAuthor(s): Fatemeh Rasouli, Kyle B. ReedAbstractCrutches are one of the most common ambulatory assistive devices. Using crutches encourages more physical activity than many other assistive devices, which has long-term health benefits. Recent advances have led to improvements in performance, but using crutches remains slower than normal walking, are energetically inefficient, cause additional strain on upper extremities, and often result in abrasions on the skin. Further improvements to address these deficiencies are needed but require an understanding of the crutch users’ disabilities, different crutch gait patterns, associated biomechanics, and how the crutch design interacts with the user. It is important that research studies and designs take into account parameters from multiple ways of measuring performance in order for impaired users to achieve effective crutch walking. Many existing studies of crutches only analyze a subset of quantitative variables, so the overall impact of a design or modification is not fully assessed or comparable to other designs. Another important aspect is the user; each crutch type has specific characteristics that need to match the user’s ability, physical fitness, and gait pattern. Pain and injuries on upper extremities should also be considered as an important factor in long-term users.A search was done to find research papers and related patents focusing on crutch design and usage. Papers that studied one or more of the following topics were included: effects of crutches on the gait parameter, types of crutch walking patterns, improving walking efficiency through crutch design, and identifying the important components when studying a gait. This review paper summarizes the effects of existing crutch types and gives guidelines for how future studies should comprehensively evaluate design changes. This paper includes an overview of crutch gait walking patterns, users, the components and measurements of crutch studies, and advancements of crutch designs.
       
 
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