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Publisher: Springer-Verlag (Total: 2351 journals)

 Annals of Biomedical EngineeringJournal Prestige (SJR): 1.042 Citation Impact (citeScore): 3Number of Followers: 18      Hybrid journal (It can contain Open Access articles) ISSN (Print) 1573-9686 - ISSN (Online) 0090-6964 Published by Springer-Verlag  [2351 journals]
• Medical Robotics
• Authors: Daniel S. Elson; Kevin Cleary; Pierre Dupont; Robert Merrifield; Cameron Riviere
Pages: 1433 - 1436
PubDate: 2018-10-01
DOI: 10.1007/s10439-018-02127-7
Issue No: Vol. 46, No. 10 (2018)

• Toward a Flexible Variable Stiffness Endoport for Single-Site Partial
Nephrectomy
• Authors: E. Amanov; T.-D. Nguyen; S. Markmann; F. Imkamp; J. Burgner-Kahrs
Pages: 1498 - 1510
Abstract: Laparoscopic partial nephrectomy for localized renal tumors is an upcoming standard minimally invasive surgical procedure. However, a single-site laparoscopic approach would be even more preferable in terms of invasiveness. While the manual approach offers rigid curved tools, robotic single-site systems provide high degrees of freedom manipulators. However, they either provide only a straight deployment port, lack of instrument integration, or cannot be reconfigured. Therefore, the current main shortcomings of single-site surgery approaches include limited tool dexterity, visualization, and intuitive use by the surgeons. For partial nephrectomy in particular, the accessibility of the tumors remains limited and requires invasive kidney mobilization (separation of the kidney from the surrounding tissue), resulting in patient stress and prolonged surgery. We address these limitations by introducing a flexible, robotic, variable stiffness port with several working channels, which consists of a two-segment tendon-driven continuum robot with integrated granular and layer jamming for stabilizing the pose and shape. We investigate biocompatible granules for granular jamming and demonstrate the stiffening capabilities in terms of pose and shape accuracy with experimental evaluations. Additionally, we conduct in vitro experiments on a phantom and prove that the visualization of tumors at various sites is increased up to 38% in comparison to straight endoscopes.
PubDate: 2018-10-01
DOI: 10.1007/s10439-018-2060-4
Issue No: Vol. 46, No. 10 (2018)

• Towards Alternative Approaches for Coupling of a Soft Robotic Sleeve to
the Heart
• Authors: Markus A. Horvath; Claudia E. Varela; Eimear B. Dolan; William Whyte; David S. Monahan; Christopher J. Payne; Isaac A. Wamala; Nikolay V. Vasilyev; Frank A. Pigula; David J. Mooney; Conor J. Walsh; Garry P. Duffy; Ellen T. Roche
Pages: 1534 - 1547
Abstract: Efficient coupling of soft robotic cardiac assist devices to the external surface of the heart is crucial to augment cardiac function and represents a hurdle to translation of this technology. In this work, we compare various fixation strategies for local and global coupling of a direct cardiac compression sleeve to the heart. For basal fixation, we find that a sutured Velcro band adheres the strongest to the epicardium. Next, we demonstrate that a mesh-based sleeve coupled to the myocardium improves function in an acute porcine heart failure model. Then, we analyze the biological integration of global interface material candidates (medical mesh and silicone) in a healthy and infarcted murine model and show that a mesh interface yields superior mechanical coupling via pull-off force, histology, and microcomputed tomography. These results can inform the design of a therapeutic approach where a mesh-based soft robotic DCC is implanted, allowed to biologically integrate with the epicardium, and actuated for active assistance at a later timepoint. This strategy may result in more efficient coupling of extracardiac sleeves to heart tissue, and lead to increased augmentation of heart function in end-stage heart failure patients.
PubDate: 2018-10-01
DOI: 10.1007/s10439-018-2046-2
Issue No: Vol. 46, No. 10 (2018)

• Neuromonitoring During Robotic Cochlear Implantation: Initial Clinical
Experience
• Authors: Juan Ansó; Olivier Scheidegger; Wilhelm Wimmer; Kate Gavaghan; Nicolas Gerber; Daniel Schneider; Jan Hermann; Christoph Rathgeb; Cilgia Dür; Kai Michael Rösler; Georgios Mantokoudis; Marco Caversaccio; Stefan Weber
Pages: 1568 - 1581
Abstract: During robotic cochlear implantation a drill trajectory often passes at submillimeter distances from the facial nerve due to close lying critical anatomy of the temporal bone. Additional intraoperative safety mechanisms are thus required to ensure preservation of this vital structure in case of unexpected navigation system error. Electromyography based nerve monitoring is widely used to aid surgeons in localizing vital nerve structures at risk of injury during surgery. However, state of the art neuromonitoring systems, are unable to discriminate facial nerve proximity within submillimeter ranges. Previous work demonstrated the feasibility of utilizing combinations of monopolar and bipolar stimulation threshold measurements to discretize facial nerve proximity with greater sensitivity and specificity, enabling discrimination between safe (> 0.4 mm) and unsafe (< 0.1 mm) trajectories during robotic cochlear implantation (in vivo animal model). Herein, initial clinical validation of the determined stimulation protocol and nerve proximity analysis integrated into an image guided system for safety measurement is presented. Stimulation thresholds and corresponding nerve proximity values previously determined from an animal model have been validated in a first-in-man clinical trial of robotic cochlear implantation. Measurements performed automatically at preoperatively defined distances from the facial nerve were used to determine safety of the drill trajectory intraoperatively. The presented system and automated analysis correctly determined sufficient safety distance margins (> 0.4 mm) to the facial nerve in all cases.
PubDate: 2018-10-01
DOI: 10.1007/s10439-018-2094-7
Issue No: Vol. 46, No. 10 (2018)

• Toward Semi-autonomous Cryoablation of Kidney Tumors via Model-Independent
Deformable Tissue Manipulation Technique
• Authors: Farshid Alambeigi; Zerui Wang; Yun-hui Liu; Russell H. Taylor; Mehran Armand
Pages: 1650 - 1662
Abstract: We present a novel semi-autonomous clinician-in-the-loop strategy to perform the laparoscopic cryoablation of small kidney tumors. To this end, we introduce a model-independent bimanual tissue manipulation technique. In this method, instead of controlling the robot, which inserts and steers the needle in the deformable tissue (DT), the cryoprobe is introduced to the tissue after accurate manipulation of a target point on the DT to the desired predefined insertion location of the probe. This technique can potentially reduce the risk of kidney fracture, which occurs due to the incorrect insertion of the probe within the kidney. The main challenge of this technique, however, is the unknown deformation behavior of the tissue during its manipulation. To tackle this issue, we proposed a novel real-time deformation estimation method and a vision-based optimization framework, which do not require prior knowledge about the tissue deformation and the intrinsic/extrinsic parameters of the vision system. To evaluate the performance of the proposed method using the da Vinci Research Kit, we performed experiments on a deformable phantom and an ex vivo lamb kidney and evaluated our method using novel manipulability measures. Experiments demonstrated successful real-time estimation of the deformation behavior of these DTs while manipulating them to the desired insertion location(s).
PubDate: 2018-10-01
DOI: 10.1007/s10439-018-2074-y
Issue No: Vol. 46, No. 10 (2018)

• In-Human Robot-Assisted Retinal Vein Cannulation, A World First
• Authors: Andy Gijbels; Jonas Smits; Laurent Schoevaerdts; Koen Willekens; Emmanuel B. Vander Poorten; Peter Stalmans; Dominiek Reynaerts
Pages: 1676 - 1685
Abstract: Retinal Vein Occlusion (RVO) is a blinding disease caused by one or more occluded retinal veins. Current treatment methods only focus on symptom mitigation rather than targeting a solution for the root cause of the disorder. Retinal vein cannulation is an experimental eye surgical procedure which could potentially cure RVO. Its goal is to dissolve the occlusion by injecting an anticoagulant directly into the blocked vein. Given the scale and the fragility of retinal veins on one end and surgeons’ limited positioning precision on the other, performing this procedure manually is considered to be too risky. The authors have been developing robotic devices and instruments to assist surgeons in performing this therapy in a safe and successful manner. This work reports on the clinical translation of the technology, resulting in the world-first in-human robot-assisted retinal vein cannulation. Four RVO patients have been treated with the technology in the context of a phase I clinical trial. The results show that it is technically feasible to safely inject an anticoagulant into a $$100\,{\mu} {\rm m}$$ -thick retinal vein of an RVO patient for a period of 10 min with the aid of the presented robotic technology and instrumentation.
PubDate: 2018-10-01
DOI: 10.1007/s10439-018-2053-3
Issue No: Vol. 46, No. 10 (2018)

• Novel In Vitro Test Systems and Insights for Transcatheter Mitral Valve
Design, Part I: Paravalvular Leakage
• Abstract: While transcatheter mitral valve (TMV) replacement technology has great clinical potential for surgically inoperable patients suffering from mitral regurgitation, no TMV has yet achieved regulatory approval. The diversity of devices currently under development reflects a lack of consensus regarding optimal design approaches. In Part I of this two-part study, a test system was developed for the quantification of paravalvular leakage (PVL) following deployment of a TMV or TMV-like device in pressurized, explanted porcine hearts (N = 7). Using this system, PVL rate was investigated as a function of steady trans-mitral pressure (ΔP), TMV shape, and TMV-annular oversizing, using a series of “mock TMV plug” devices. Across all devices, PVL was found to approximately trend with the square of ΔP. PVL rates were approximately 0–15 mL/s under hypotensive pressure, 10–40 mL/s under normotension, and 30–85 mL/s under severe hypertension. D-shaped devices significantly reduced PVL vs. circular devices; however, this effect was diminished upon oversizing to the annulus by 6 mm inter-trigonal distance. In conclusion, this steady pressure, in vitro test system was effective to compare PVL performance across TMV-like designs. PVL exhibited complex dynamics in terms of its response to transvalvular pressure and TMV profile.
PubDate: 2018-10-17

• The Shrinking Brain: Cerebral Atrophy Following Traumatic Brain Injury
• Abstract: Cerebral atrophy in response to traumatic brain injury is a well-documented phenomenon in both primary investigations and review articles. Recent atrophy studies focus on exploring the region-specific patterns of cerebral atrophy; yet, there is no study that analyzes and synthesizes the emerging atrophy patterns in a single comprehensive review. Here we attempt to fill this gap in our current knowledge by integrating the current literature into a cohesive theory of preferential brain tissue loss and by identifying common risk factors for accelerated atrophy progression. Our review reveals that observations for mild traumatic brain injury remain inconclusive, whereas observations for moderate-to-severe traumatic brain injury converge towards robust patterns: brain tissue loss is on the order of 5% per year, and occurs in the form of generalized atrophy, across the entire brain, or focal atrophy, in specific brain regions. The most common regions of focal atrophy are the thalamus, hippocampus, and cerebellum in gray matter and the corpus callosum, corona radiata, and brainstem in white matter. We illustrate the differences of generalized and focal gray and white matter atrophy on emerging deformation and stress profiles across the whole brain using computational simulation. The characteristic features of our atrophy simulations—a widening of the cortical sulci, a gradual enlargement of the ventricles, and a pronounced cortical thinning—agree well with clinical observations. Understanding region-specific atrophy patterns in response to traumatic brain injury has significant implications in modeling, simulating, and predicting injury outcomes. Computational modeling of brain atrophy could open new strategies for physicians to make informed decisions for whom, how, and when to administer pharmaceutical treatment to manage the chronic loss of brain structure and function.
PubDate: 2018-10-17

• Novel In Vitro Test Systems and Insights for Transcatheter Mitral Valve
Design, Part II: Radial Expansion Forces
• Abstract: Transcatheter mitral valve (TMV) replacement technology has great clinical potential for surgically inoperable patients suffering from mitral regurgitation. An important goal for robust TMV design is maximizing the likelihood of achieving a geometry post-implant that facilitates optimal performance. To support this goal, improved understanding of the annular forces that oppose TMV radial expansion is necessary. In Part II of this study, novel circular and D-shaped Radial Expansion Force Transducers (C-REFT and D-REFT) were developed and employed in porcine hearts (N = 12), to detect the forces required to radially expand the mitral annulus to discrete oversizing levels. Forces on both the septal-lateral and inter-commissural axes (FSL and FIC) scaled with device size. The D-REFT experienced lower FSL than the C-REFT (19.8 ± 7.4 vs. 17.4 ± 10.8 N, p = 0.002) and greater FIC (31.5 ± 14.0 vs. 36.9 ± 16.2 N; p = 0.002), and was more sensitive to degree of oversizing. Across all tests, FIC/FSL was 2.21 ± 1.33, likely reflecting low resistance to radial expansion at the aorto-mitral curtain. In conclusion, the annular forces opposing TMV radial expansion are non-uniform, and depend on final TMV shape and size. Based on this two-part study, we propose that radial force applied at the commissural aspect of the annulus has the most potent effect on paravalvular sealing.
PubDate: 2018-10-17

• Development of Open-Source Dummy and Impactor Models for the Assessment of
American Football Helmet Finite Element Models
• Abstract: The objective of this study was to develop and validate a set of Hybrid-III head and neck (HIII-HN) and impactor models that can be used to assess American football design modifications with established dummy-based injury metrics. The model was validated in two bare-head impact test configurations used by the National Football League and research groups to rank and assess helmet performance. The first configuration was a rigid pendulum impact to three locations on the HIII head (front, rear, side) at 3 m/s. The second configuration was a set of eight 5.5 m/s impacts to the HIII head at different locations using a linear impactor with a compliant end cap. The ISO/TS 18571 objective rating metric was used to quantify the correlation between the experimental and model head kinematics (linear and rotational velocity and acceleration) and neck kinetics (neck force and moment). The HIII-HN model demonstrated good correlation with overall mean ISO scores of 0.69–0.78 in the pendulum impacts and 0.65–0.81 in the linear impacts. These publically available models will serve as an in silico design platform that will be useful for investigating novel football helmet designs and studying human head impact biomechanics, in general.
PubDate: 2018-10-16

• Impact of Factors that Affect Reading Skill Level on King–Devick
Baseline Performance Time
• Abstract: The King–Devick (K–D) test is often used as part of a multimodal assessment to screen for sport-related concussion. However, the test involves reading numbers, and little is known about variation in baseline performance on the K–D by reading skill level. We conducted a cross-sectional study analyzing data from the Concussion Assessment, Research and Education (CARE) Consortium to assess differences in baseline performance on the K–D associated with factors that impact reading skill level (learning disorder [LD] and primary home language other than English [PHLOTE]), while controlling for covariates (gender, type of sport, attentional issues, history of concussion and modality of administration). We had a sample of 2311 student-athletes (47% female), and multivariate regression indicated an average K–D performance time of 40.4 s. Presence of LD was associated with a 3.3 s slower K–D time (95% CI 1.9–4.7, p < 0.001), and PHLOTE was associated with a 2.6 s slower K–D time (95% CI 1.2–4.0, p < 0.001), after controlling for other covariates. These results suggest caution in the use of normative data with the K–D. Future studies should explore the impact of factors associated with reading skill level on sensitivity of the K–D in detecting concussion.
PubDate: 2018-10-12

• Sonodynamic Therapy on Intracranial Glioblastoma Xenografts Using
Sinoporphyrin Sodium Delivered by Ultrasound with Microbubbles
• Abstract: Sonodynamic therapy (SDT) is a promising noninvasive method for cancer treatment. The anti-tumor effect of sinoporphyrin sodium (DVDMS)-mediated SDT on nude mice bearing intracranial U87 MG-Red-FLuc human glioblastoma was investigated. Focused ultrasound (FUS) with microbubbles (MBs) was utilized to open the blood-brain barrier for enhancing the delivery of the sonosensitizer DVDMS to the brain tumor first, and then the SDT treatment was performed. The in vitro study showed obvious cytotoxicity of DVDMS-mediated SDT (center frequency: 0.996 MHz, acoustic power: 1.7 W, pulse repletion frequency: 1 Hz, duty cycle: 30%, duration: 1 min) on U87 MG-Red-FLuc cells. The results indicated that more DVDMS accumulation in the tumor sites was induced by FUS with MBs by 3.43 folds of unsonicated ones. Longitudinal bioluminescence imaging illustrated that the intracranial glioblastoma progression in nude mice treated with SDT was retarded compared to the untreated group. The median survival time was prolonged to 30.25 days after SDT treatment by 27.37%. The anti-proliferation effect and cell apoptosis induction was further confirmed by immunohistochemical examinations. These results of the study suggested that SDT using the sonosensitizer DVDMS delivered by FUS with MBs may provide a new promising therapeutic strategy against glioblastoma.
PubDate: 2018-10-12

• Fecobionics: A Novel Bionics Device for Studying Defecation
• Abstract: During defecation, solid, semisolid or liquid stools are eliminated via the anus in a complex physiological process. Up to 25% of the population are affected by anorectal disorders that are poorly recognized and treated. We developed a new bionics device, a simulated stool named Fecobionics, to replace several current tests of anorectal function. Fecobionics was developed to simulate the defecation process that depends on rectal forces, the anorectal size angle, and anorectal size and sensitivity. Fecobionics provided axial pressure signatures, measurement of bending (anorectal angle) and geometric mapping in a single examination. It had the consistency and shape of normal stool. The device had a soft core with embedded electronics and a bag for distension. The paper describes the device development and validation. Furthermore, data were obtained in preliminary experiments in pigs, healthy human subjects and patients with focus on four important features of the system, i.e. measurements of pressure signatures, bending characteristics, impedance measurements and data transmission. Accurate pressure and orientation data as well as geometric profiles were successfully obtained on the bench as well as in vivo in pigs and human subjects during defecation. Fecobionics is a novel technology imitating defecation. The clinical future ultimately depends on its ability to impact on daily treatment of anorectal disorders. A potential long-term clinical application is use of the device for biofeedback training for dyssynergic defecation.
PubDate: 2018-10-11

• Modeling Human Volunteers in Multidirectional, Uni-axial Sled Tests Using
a Finite Element Human Body Model
PubDate: 2018-10-11
DOI: 10.1007/s10439-018-02147-3

• Applications of Wireless Power Transfer in Medicine: State-of-the-Art
Reviews
• Authors: Julian Moore; Sharon Castellanos; Sheng Xu; Bradford Wood; Hongliang Ren; Zion Tsz Ho Tse
Abstract: Magnetic resonance within the field of wireless power transfer has seen an increase in popularity over the past decades. This rise can be attributed to the technological advances of electronics and the increased efficiency of popular battery technologies. The same principles of electromagnetic theory can be applied to the medical field. Several medical devices intended for use inside the body use batteries and electrical circuits that could be powered wirelessly. Other medical devices limit the mobility or make patients uncomfortable while in use. The fundamental theory of electromagnetics can improve the field by solving some of these problems. This survey paper summarizes the recent uses and discoveries of wireless power in the medical field. A comprehensive search for papers was conducted using engineering search engines and included papers from related conferences. During the initial search, 247 papers were found then non-relevant papers were eliminated to leave only suitable material. Seventeen relevant journal papers and/or conference papers were found, then separated into defined categories: Implants, Pumps, Ultrasound Imaging, and Gastrointestinal (GI) Endoscopy. The approach and methods for each paper were analyzed and compared yielding a comprehensive review of these state of the art technologies.
PubDate: 2018-10-10
DOI: 10.1007/s10439-018-02142-8

• Health-Related Quality of Life Following Concussion in Collegiate
Student-Athletes With and Without Concussion History
• Authors: M. L. Weber; CARE Consortium Investigators; R. C. Lynall; N. L. Hoffman; E. H. Miller; T. W. Kaminski; T. A. Buckley; H. J. Benjamin; C. M. Miles; C. T. Whitlow; L. Lintner; S. P. Broglio; M. McCrea; T. McAllister; J. D. Schmidt
Abstract: The purpose of this study was to compare global and specific health-related quality of life (HRQOL) throughout concussion recovery between those with and without concussion history. Student-athletes diagnosed with concussion completed global (Short Form-12v2; SF-12) and specific (Hospital Anxiety and Depression Scale: HADS) HRQOL assessments at baseline, 24–48 h, asymptomatic, return-to-play, and 6-months post-injury. Baseline scores were compared to post-injury time points for SF-12 subscores (physical and mental; PCS-12, MCS-12) and HADS subscores (depression and anxiety; HADS-D, HADS-A). We conducted a 2 × 5 mixed model ANOVA for group (with and without concussion history) and time (four post-injury assessments compared to baseline). We did not observe interaction or main effects for group, except those with concussion history had worse HADS-D subscores than those without concussion history. PCS-12 subscores were worse at 24–48 h, asymptomatic, and return-to-play compared to baseline, but returned to baseline 6-months post-injury. MCS-12 subscores did not differ at any time points. HADS-D subscores worsened 24–48 h post-injury, but improved for additional assessments compared to baseline. HADS-A improved post-injury compared to baseline at asymptomatic, return-to-play, and 6-month assessments, but was similar to baseline 24–48 h post-injury. HRQOL physical aspects slightly worsened post-injury and restored to baseline after returning to play.
PubDate: 2018-10-09
DOI: 10.1007/s10439-018-02151-7

• Pentagalloyl Glucose and Its Functional Role in Vascular Health:
Biomechanics and Drug-Delivery Characteristics
• Authors: Sourav S. Patnaik; Dan T. Simionescu; Craig J. Goergen; Kenneth Hoyt; Shashank Sirsi; Ender A. Finol
Abstract: Pentagalloyl glucose (PGG) is an elastin-stabilizing polyphenolic compound that has significant biomedical benefits, such as being a free radical sink, an anti-inflammatory agent, anti-diabetic agent, enzymatic resistant properties, etc. This review article focuses on the important benefits of PGG on vascular health, including its role in tissue mechanics, the different modes of pharmacological administration (e.g., oral, intravenous and endovascular route, intraperitoneal route, subcutaneous route, and nanoparticle based delivery and microbubble-based delivery), and its potential therapeutic role in vascular diseases such as abdominal aortic aneurysms (AAA). In particular, the use of PGG for AAA suppression and prevention has been demonstrated to be effective only in the calcium chloride rat AAA model. Therefore, in this critical review we address the challenges that lie ahead for the clinical translation of PGG as an AAA growth suppressor.
PubDate: 2018-10-08
DOI: 10.1007/s10439-018-02145-5

• Evaluation of Drug-Loaded Gold Nanoparticle Cytotoxicity as a Function of
Tumor Vasculature-Induced Tissue Heterogeneity
• Authors: Hunter A. Miller; Hermann B. Frieboes
Abstract: The inherent heterogeneity of tumor tissue presents a major challenge to nanoparticle-mediated drug delivery. This heterogeneity spans from the molecular (genomic, proteomic, metabolomic) to the cellular (cell types, adhesion, migration) and to the tissue (vasculature, extra-cellular matrix) scales. In particular, tumor vasculature forms abnormally, inducing proliferative, hypoxic, and necrotic tumor tissue regions. As the vasculature is the main conduit for nanotherapy transport into tumors, vasculature-induced tissue heterogeneity can cause local inadequate delivery and concentration, leading to subpar response. Further, hypoxic tissue, although viable, would be immune to the effects of cell-cycle specific drugs. In order to enable a more systematic evaluation of such effects, here we employ computational modeling to study the therapeutic response as a function of vasculature-induced tumor tissue heterogeneity. Using data with three-layered gold nanoparticles loaded with cisplatin, nanotherapy is simulated interacting with different levels of tissue heterogeneity, and the treatment response is measured in terms of tumor regression. The results quantify the influence that varying levels of tumor vascular density coupled with the drug strength have on nanoparticle uptake and washout, and the associated tissue response. The drug strength affects the proportion of proliferating, hypoxic, and necrotic tissue fractions, which in turn dynamically affect and are affected by the vascular density. Higher drug strengths may be able to achieve stronger tumor regression but only if the intra-tumoral vascular density is above a certain threshold that affords sufficient transport. This study establishes an initial step towards a more systematic methodology to assess the effect of vasculature-induced tumor tissue heterogeneity on the response to nanotherapy.
PubDate: 2018-10-08
DOI: 10.1007/s10439-018-02146-4

• Selective Enzymatic Digestion of Proteoglycans and Collagens Alters
Cartilage T1rho and T2 Relaxation Times
• Authors: Amber T. Collins; Courtney C. Hatcher; Sophia Y. Kim; Sophia N. Ziemian; Charles E. Spritzer; Farshid Guilak; Louis E. DeFrate; Amy L. McNulty
Abstract: Our objective was to determine the relationship of T1rho and T2 relaxation mapping to the biochemical and biomechanical properties of articular cartilage through selective digestion of proteoglycans and collagens. Femoral condyles were harvested from porcine knee joints and treated with either chondroitinase ABC (cABC) followed by collagenase, or collagenase followed by cABC. Magnetic resonance images were acquired and cartilage explants were harvested for biochemical, biomechanical, and histological analyses before and after each digestion. Targeted enzymatic digestion of proteoglycans with cABC resulted in elevated T1rho relaxation times and decreased sulfated glycosaminoglycan content without affecting T2 relaxation times. In contrast, extractable collagen and T2 relaxation times were increased by collagenase digestion; however, neither was altered by cABC digestion. Aggregate modulus decreased with digestion of both components. Overall, we found that targeted digestion of proteoglycans and collagens had varying effects on biochemical, biomechanical, and imaging properties. T2 relaxation times were altered with changes in extractable collagen, but not changes in proteoglycan. However, T1rho relaxation times were altered with proteoglycan loss, which may also coincide with collagen disruption. Since it is unclear which matrix components are disrupted first in osteoarthritis, both markers may be important for tracking disease progression.
PubDate: 2018-10-04
DOI: 10.1007/s10439-018-02143-7

• Lower Limb Posture Affects the Mechanism of Injury in Under-Body Blast
• Authors: Grigoris Grigoriadis; Diagarajen Carpanen; Claire E. Webster; Arul Ramasamy; Nicolas Newell; Spyros D. Masouros
Abstract: Over 80% of wounded Service Members sustain at least one extremity injury. The ‘deck-slap’ foot, a product of the vehicle’s floor rising rapidly when attacked by a mine to injure the limb, has been a signature injury in recent conflicts. Given the frequency and severity of these combat-related extremity injuries, they require the greatest utilisation of resources for treatment, and have caused the greatest number of disabled soldiers during recent conflicts. Most research efforts focus on occupants seated with both tibia-to-femur and tibia-to-foot angles set at 90°; it is unknown whether results obtained from these tests are applicable when alternative seated postures are adopted. To investigate this, lower limbs from anthropometric testing devices (ATDs) and post mortem human subjects (PMHSs) were loaded in three different seated postures using an under-body blast injury simulator. Using metrics that are commonly used for assessing injury, such as the axial force and the revised tibia index, the lower limb of ATDs were found to be insensitive to posture variations while the injuries sustained by the PMHS lower limbs differed in type and severity between postures. This suggests that the mechanism of injury depends on the posture and that this cannot be captured by the current injury criteria. Therefore, great care should be taken when interpreting and extrapolating results, especially in vehicle qualification tests, when postures other than the 90°–90° are of interest.
PubDate: 2018-10-01
DOI: 10.1007/s10439-018-02138-4

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