nils-herrmann/clean_scirepeval huggingface dataset:
Plantar pressure distribution and spatiotemporal gait parameters after the radial shock wave therapy in patients with chronic plantar fasciitis.
Venue: Journal of biomechanics

Radial shock wave therapy (RSWT) has been recommended as an appropriate, safe and effective method in the treatment of chronic plantar fasciitis (PF). The main purpose of this study was to examine how RSWT affects gait parameters. This study included 23 patients with unilateral, chronic PF. RSWT were administered in 5 interventions, during a consecutive 3-week period. Objective kinetic (force distribution under the forefoot, midfoot, rearfoot) and spatiotemporal parameters (cadence, step length, stance phase duration) during treadmill walking at, preferred" speed were evaluated on. 4 sessions: before therapy, immediately after (primary endpoint), 3 and 6 weeks after therapy. The mean reduction in the reported pain when taking first steps in the morning from baseline to the primary endpoint, 3- and 6-weeks post procedure was 42.7%, 50.1% and 66.9% respectively. Similar reduction was seen in the reported pain during walking. After the therapy during gait at the preferred speed patients had a significantly higher force beneath the rearfoot and forefoot of both limbs. Force beneath the midfoot was not significantly affected by treatment. The step length in both limbs increased by 3.3-3.6 cm after RSWT. After the therapy stance phase duration in symptomatic foot was longer by 7% and it slightly decreased until POST-6wk. Similar changes were seen in an asymptomatic limb. The spatiotemporal and kinetic results indicate that RSWT therapy induces changes in patient's gait structure and alter regional loading in the affected foot.
High density muscle size and muscle power are associated with both gait and sit-to-stand kinematic parameters in frail nonagenarians.
Venue: Journal of biomechanics

Frailty is an important concept in clinical and demographic research in the elderly because of its incidence level and its relationship with adverse outcomes. Functional ability declines with advanced age, likely due to changes in muscle function. This study aimed to examine the relationship between muscle quality and muscle power with kinematics from functional tests in a population of 21 institutionalized frail nonagenarian (91.3 ± 3.1 years). Here, muscle quality was measured by segmenting areas of high- and low-density fibers with computerized tomography. In addition, muscle strength and muscle power were obtained through maximal strength and power tests using resistance exercises. Finally, functional capacity outcomes (i.e., balance, gait velocity and sit-to-stand ability), as well as kinematic parameters, were evaluated from a tri-axial sensor used during a battery of functional tests. Our results show that lower limb muscle quality, maximal strength and power output present statistically significant relationships with different kinematic parameters, especially during the sit-to-stand and gait tests (e.g. leg power and maximum power during sit-to-stand (r = 0.80) as well as quadriceps muscle mass and step asymmetry (r = -0,71). In particular, frail individuals with greater muscle quality needed less trunk range of motion to make the transition between sitting and standing, took less time to stand up, and exerted a major peak power of force. As a conclusion, a loss of muscle quality and power may lead to motor control impairments such as gait, sit-to-stand and balance that can be the cause of adverse events such as falls.
Load carriage magnitude and locomotion strategy alter knee total joint moment during bipedal ambulatory tasks in recruit-aged women.
Venue: Journal of biomechanics

Knee osteoarthritis (OA) is prevalent among female soldiers, resulting in limited duty and long term adverse ambulatory effects. A proposed mechanism to the development of knee OA is the assiduous execution of load carriage tasks. Soldiers are often required to maintain a walking gait with load at velocities beyond their gait transition velocity (GTV) known as forced marching. The primary aim of this investigation is to determine the interactive effects of load magnitude and locomotion pattern on relative knee total joint moment (KTJM) in healthy recruit-aged women. The secondary aims are to determine knee total joint moment limb differences and to determine the interactive effect of load magnitude and locomotion pattern on the percent contributions of each plane of motion moment. Individuals were tasked with running and forced marching at 10% above their GTV at body weight (BW) and with an additional 25% and 45% of their BW. KTJM was analyzed at two specific gait events of heel-strike and mid-stance. At heel-strike, forced marching exhibited greater KTJM compared to run for all load conditions but running had greater KTJM than forced marching at mid-stance. The forced marching pattern exhibited larger KTJM for the dominant limb at both gait events compared to running. Lastly, at mid-stance the knee adduction moment percent (KAM%) contribution was greater for forced marching compared to running. The forced marching pattern demonstrates joint kinetics that may be more deleterious with prolonged exposure. Likewise, forced marching induced KAM% similar to those already suffering from knee OA.
Evaluation of brain-skull interface modelling approaches on the prediction of acute subdural hematoma in the elderly.
Venue: Journal of biomechanics

Acute subdural hematoma (ASDH) in the elderly is currently a matter of concern due to the growing number of the aging population and their higher incident rate compared to the younger adults. Computational head models that can replicate this age-related injury pattern are valuable tools to help addressing this concern. Although a biofidelic brain-skull interface modelling strategy is essential for accurate ASDH prediction, approaches with different simplifications have been used in existing head models to simulate the interaction between the brain and skull with their ASDH predictability unknown. Thus, the current communication evaluates the applicability of different brain-skull interface modelling approaches for ASDH prediction associated with age-related brain atrophy. Four representative approaches are selected by simulating cerebrospinal fluid (CSF) as Lagrangian-represented solid and Arbitrary Lagrangian-Eulerian (ALE) represented fluid, each with or without tangential sliding aginst the brain. The chosen approaches are implemented in three models with various degrees of atrophied brain, which are subsequently exposed to an experimentally measured loading known to cause ASDH. The results show, only when simulating the CSF as ALE elements with sliding interface against the brain, a relatively higher ASDH risk characterized by increased cortical relative motion and BV strain peaks are predicted by the atrophied model without causing excessive mesh distortion in the CSF elements. The results of this study provide guidance for brain-skull interface modelling, particularly for the prediction of ASDH in different age groups.
Biomechanical mechanism of Tai-Chi gait for preventing falls: A pilot study.
Venue: Journal of biomechanics

Chi (TC) practice has been increasingly used to prevent falls in older adults. However, the biomechanical mechanisms underlying the effects of TC practice on fall risk among older adults remain unanswered. The objective of this pilot study was to examine how TC gait biomechanically impacts the human body in terms of dynamic gait stability and lower limb muscle strength in comparison with regular walking gait. Ten healthy adults performed five trials of TC gait following three to seven trials of regular walking. Full body kinematics and kinetics were collected, and then dynamic gait stability and lower limb joint moments were determined. During TC gait, individuals were less stable, moved more slowly and experienced a larger mediolateral movement in comparison with regular walking gait. The peak moment at the ankle joint on the sagittal and transverse planes, at the knee joint on all three planes, and at the hip joint on the frontal plane was significantly different when performing TC gait than during regular gait. The results indicate that TC gait challenges body balance and requires more muscle strength of the lower limb joints compared to regular walking gait. To cope with these challenges, the body could develop neuromuscular control strategies to maintain body balance and thus reduce the risk of falls. The findings and methodology in this study could provide preliminary guidance for identifying optimal TC forms in order to maximize the effects of TC-based fall prevention interventions among various populations with elevated risk of falls.
As the endothelial cell reorients, its tensile forces stabilize.
Venue: Journal of biomechanics

When adherent cells are subjected to uniaxial sinusoidal stretch at frequencies close to physiological, their body and their contractile stress fibers realign nearly perpendicularly to the stretch axis. A common explanation for this phenomenon is that stress fibers reorient along the direction where they are unaffected by the applied cyclic stretch and thus can maintain optimal (homeostatic) tensile force. The ability of cells to achieve tensional homeostasis in response to external disturbances is important for normal physiological functions of cells and tissues and it provides protection against diseases, including cancer and atherosclerosis. However, quantitative experimental data that support the idea that stretch-induced reorientation is associated with tensional homeostasis are lacking. We observed previously that in response to uniaxial cyclic stretch of 10% strain amplitudes, traction forces of single endothelial cells reorient in the direction perpendicular to the stretch axis. Here we carried out a secondary analysis of those data to investigate whether this reorientation of traction forces is associated with tensional homeostasis. Our analysis showed that stretch-induced reorientation of traction forces was accompanied by attenuation of temporal variability of the traction field to the level that was observed in the absence of stretch. These findings represent a quantitative experimental evidence that stretch-induced reorientation of cellular traction forces is associated with the cell's tendency to achieve tensional homeostasis.
Ultrasound echogenicity is associated with fatigue-induced failure in a cadaveric Achilles tendon model.
Venue: Journal of biomechanics

Achilles tendon disorders are among the most difficult sports-related injuries to predict with current diagnostic tools. The purpose of this study was to identify a clinically useful marker for early tendon damage. We hypothesized that alterations in mean echogenicity are linked with changes in vitro tendon mechanics. To test our hypothesis, we harvested Achilles tendons from 10 fresh-frozen cadaveric feet and cyclically fatigued them using a universal test frame while we continuously acquired ultrasound images. Throughout this fatigue protocol, we applied 2 stress tests every 500 loading cycles to quantify changes in ultrasound imaging echogenicity. We continued this fatigue protocol until each tendon either failed completely or survived 150,000 cycles. Tendons that failed during the fatigue loading (6/10) underwent greater changes in mean echogenicity compared to tendons that did not fail (P = 0.031). These tendons that failed during fatigue loading demonstrated greater changes in mean echogenicity that surpassed 1.0%; whereas survivor tendons exhibited less than 0.5% changes in mean echogenicity. We found that changes in mean echogenicity measured with ultrasound increased proportionally with increased tendon damage. The magnitude of these changes was relatively small (<1.5% change in mean echogenicity) but may be an effective predictor of tendon failure. Mean echogenicity is a promising marker for quantifying fatigue damage in cadaveric Achilles tendons during a stress test. Although these changes cannot be detected with the naked eye, computer-based predictive models may effectively assess risk of tendon damage in physically active adults.
Heterogeneous matrix deposition in human tissue engineered cartilage changes the local shear modulus and resistance to local construct buckling.
Venue: Journal of biomechanics

Human tissue engineered cartilage is a promising solution for focal cartilage defects, but these constructs do not have the same local mechanical properties as native tissue. Most clinically relevant engineered cartilage constructs seed human chondrocytes onto a collagen scaffold, which buckles at low loads and strains. This buckling creates local regions of high strain that could cause cell death and damage the engineered tissue. Since human tissue engineered cartilage is commonly grown in-vivo prior to implantation, new matrix deposition could improve the local implant mechanics and prevent local tissue buckling. However, the relationship between local biochemical composition and the local mechanics or local buckling probability has never been quantified. Therefore, this study correlated the local biochemical composition of human tissue engineered cartilage constructs using Fourier transform infrared spectroscopy (FTIR) with the local shear modulus and local buckling probability. The local shear modulus and local buckling probability were obtained using a confocal elastography technique. The local shear modulus increased with increases in local aggrecan content in the interior region (inside the scaffold). A minimum amount of aggrecan was required to prevent local construct buckling at physiologic strains. Since the original scaffold was primarily composed of collagen, increases in collagen content due to new matrix deposition was minimal and had little effect on the mechanical properties. Thus, we concluded that aggrecan deposition inside the scaffold pores is the most effective way to improve the mechanical function and prevent local tissue damage in human tissue engineered cartilage constructs.
Biomechanical analysis of common solid waste collection throwing techniques using OpenSim and an EMG-assisted solver.
Venue: Journal of biomechanics

The solid waste collection industry is one of the most common occupations resulting in low back pain (LBP). Lumbar peak joint reaction forces and peak and integrated moments are strong correlates of LBP. To investigate these risks, this study compared three common waste collection throwing techniques of varying lumbar symmetry: the symmetric (SYM) technique, the asymmetric fixed stance (AFS) technique, and the asymmetric with pivot (AWP) technique. Lumbar moments and joint reaction loads were computed for throwing garbage bags of 3, 7, and 11 kg to quantify the effects that technique and object weight have on LBP risk. LBP risk factors were computed using a full-body musculoskeletal model in OpenSim. Muscle activations were estimated using two methods: the EMG-assisted method, which included electromyography data in the solution, and the conventional static optimization method, which did not. The EMG-assisted method more accurately reproduced measured muscle activation, resulting in significantly larger peak compressive and shear forces (p < 0.05) of magnitudes indicative of LBP risk. Risk factors associated with the SYM technique were either larger or not statistically different compared to the asymmetric techniques for the 3 kg condition; however, the opposite result occurred for the 7 and 11 kg conditions (p < 0.05). These results suggest using rapid, asymmetric techniques when handling lightweight objects and slower, symmetric techniques for heavier objects to reduce LBP risk during waste collection throwing techniques. Results indicating increased risk between asymmetric techniques were mostly inconclusive. As expected, increasing bag mass generally increased LBP risk factors, regardless of technique (p < 0.05).
Effect of intervertebral disc degeneration on mechanical and electric signals at the interface between disc and vertebra.
Venue: Journal of biomechanics

Intervertebral disc (IVD) degeneration is significantly correlated with the changes in structure and material properties of adjacent vertebral bone, possibly through mechanical and electrical interactions. However, the mechanisms underlying the alteration of the mechanical and electrical environment at the disc-vertebra interface related with disc degeneration have not been well studied. The objective of this study was to numerically investigate the long-term distributions of mechanical and electrical signals on the disc-vertebra interface with disc degeneration. A three-dimensional finite element model of a human lumbar IVD was used to study the mechanical and electric signals at the interface between disc and vertebral body. The disc degeneration was simulated by reducing the nutrition levels on the nucleus pulposus (NP)-vertebra interface and on the annulus fibrosus (AF) periphery to 30% and 60% of its normal values, respectively. In the simulation, the total external mechanical load applied to the disc-vertebra segment was assumed unchanged during disc degeneration. The simulation results showed that the compressive stress of solid matrix changed by up to ~37 kPa on the NP-vertebra interface, while it increased by up to ~32 kPa on the AF-vertebra interface. The shear stress increased by up to ~37 kPa with disc degeneration. The absolute value of the electric potential on the disc-vertebra interface of the disc slightly decreased with the disc degeneration (~0.5 mV). The knowledge of these spatial and temporal variations of the mechanical stresses and electric potential on the disc-vertebra interface is important for understanding the vertebrae adaptation and remodeling during disc degeneration.
Experimental and numerical study on the performance of printed alginate/hyaluronic acid/halloysite nanotube/polyvinylidene fluoride bio-scaffolds.
Venue: Journal of biomechanics

The growing usage of printed bio scaffolds in the field of regenerative medicine has made this field very important in biomedical engineering. In this regard, three-dimensional printing (3D) technique needs bio-materials with higher mechanical and biological performance. The biomaterials with high mechanical performance beside its bio compatibility are limited. A novel bio-material made of Alginate, Hyaluronic acid, Halloysite Nanotube and Polyvinylidene Fluoride was used and characterized for printing cartilage bio scaffolds through numerical studies. CaCl2 was used for crosslinking of biomaterial. Scanning Electron Microscopy, mechanical tests (tensile and compressive test), MTT assay were conducted for evaluating this novel biomaterial. Different structures of bio material were simulated for numerical studies. The numerical study was performed in ANSYS 18 using three parameter Mooney-Rivlin model. According to experimental and numerical results, Halloysite Nanotube increases the tensile and compressive strength of biomaterial up to 47%. Results show that biomaterial have good mechanical performance due to mechanical forces required for cartilage bio scaffolds besides its high biological performance. Polyvinylidene fluoride reduces the mechanical performance while increasing the cell viability. MTT assay results performed on day 0, day 2 and day 6 show increase in cell number to be about twice for biomaterial containing 40 mg/ml alginate, 40 mg/ml halloysite nanotube, 10 mg/ml hyaluronic acid and 1 w/v Polyvinylidene fluoride. Numerical simulation shows high mechanical performance of bio material in different scaffolds structure. The best structure of bio scaffolds was achieved with 0.4 mm nozzle diameter and 0.4 space between rows.
Correction of bias in the estimation of cell volume fraction from histology sections.
Venue: Journal of biomechanics

Accurate determination of the fraction of a tissue's volume occupied by cells is critical for studying tissue development, pathology, and biomechanics. For example, homogenization methods that predict the function and responses of tissues based upon the properties of the tissue's constituents require estimates of cell volume fractions. A common way to estimate cellular volume fraction is to image cells in thin, planar histologic sections, and then invoke either the Delesse or the Glagolev principle to estimate the volume fraction from the measured area fraction. The Delesse principle relies upon the observation that for randomly aligned, identical features, the expected value of the observed area fraction of a phase equals the volume fraction of that phase, and the Glagolev principle relies on a similar observation for random rather than planar sampling. These methods are rigorous for analysis of a polished, opaque rock sections and for histologic sections that are thin compared to the characteristic length scale of the cells. However, when histologic slices cannot be cut sufficiently thin, a bias will be introduced. Although this bias - known as the Holmes effect in petrography - has been resolved for opaque spheres in a transparent matrix, it has not been addressed for histologic sections presenting the opposite problem, namely transparent cells in an opaque matrix. In this note, we present a scheme for correcting the bias in volume fraction estimates for transparent components in a relatively opaque matrix.
Experimental study of prosthesis modifications based on passive dynamic walking model: A limit cycle stability analysis.
Venue: Journal of biomechanics

The aim of the current study was to examine the effect of asymmetric prosthesis derived from the passive dynamic walking (PDW) concept on dynamic stability and symmetry in unilateral transfemoral amputees. Seventeen transfemoral amputees were asked to walk on 77.8 m in preferred speed under four conditions: 1) no added mass, 2) the knee joint relocated downwards by 18% of the total shank length, shank mass decreased by 68%, thigh mass increased by 7%, 3) the knee joint relocated downwards by 37% of the total shank length, shank mass decreased by 68%, thigh mass increased by 7% and 4) thigh mass increased 17%, shank mass decreased by 38%. Trunk accelerations were recorded by a triaxle accelerometer, attached at the L3 level of spine. For each condition, stability (orbital and local), intra-limb step length and step time variability, step length and step time symmetry, were estimated from the vertical acceleration. Our findings showed no significant change in the orbital stability (P = 0.627) and the local stability (P = 0.748). In addition, no significant difference was found in the step length symmetry (P = 0.891), intra-limb step length variability (P > 0.234), the step time symmetry (P = 0.960) and intra-limb step time variability (P > 0.847) with the new prosthetic configurations. Our empirical findings indicate that contrary to the modeling predictions, manipulating physical parameters does not improve gait pattern in terms of stability, variability and symmetry in transfemoral amputees. It suggests that proposed modifications based on PDW cannot be directly applied to real human conditions without further elaborations.