nils-herrmann/clean_scirepeval huggingface dataset:
Motion of the residual femur within the socket during gait is associated with patient-reported problems in transfemoral amputees.
Venue: Journal of biomechanics

The purpose of this study was to provide a quantitative description of residual femur motion within the socket during gait and to explore the relationship between residual femur motion and patient-reported comfort and function. It was hypothesized that increased residual bone movement would correlate to worse patient-reported comfort and function. The secondary goals were to assess within-subject step-to-step variability and between-subject variability in residual femur motion within the socket during gait. Dynamic biplane radiography, combined with conventional motion capture, was used to measure residual femur motion within the socket during treadmill walking for 10 unilateral transfemoral amputees. The questionnaire for persons with a transfemoral amputation (Q-TFA) was administered to assess prosthetic use, mobility, health problems, and global health. Increased femur pistoning (proximal-distal translation relative to the socket) correlated with worsening Q-TFA problem and global scores (ρ = 0.741, p = 0.04 and ρ = -0.783, p = 0.02, respectively). Average residual femur rotation ROMs were 7.3°±3.7°, 10.8°±4.4°, and 7.7°±4.8° for anterior tilt, internal-external rotation, and varus-valgus, respectively. Average residual femur translation ROMs were 8.6 mm ± 3.0 mm, 28.4 mm ± 13.9 mm, and 20.4 mm ± 7.2 mm for medial-lateral, pistoning, and anterior-posterior directions, respectively. Within-subject rotational and translational variability during gait averaged 2.8° and 2.0 mm or less, whereas the between-subject variability was up to 9.4° and 18.6 mm, which demonstrates residual femur motion relative to the socket is repeatable within subjects, but inconsistent across subjects during gait. The results suggest residual bone motion within the socket is a potential mechanism behind patient-reported problems and suggests a target for intervention aimed at improving transfemoral amputee quality of life.
Age-related differences in gastrocnemii muscles and Achilles tendon mechanical properties in vivo.
Venue: Journal of biomechanics

Ageing is associated with alterations in the structure and function of the contractile and elastic tissues that enable movement, posture, and balance. Alterations in structure and mechanical properties of the ankle plantarflexors and Achilles tendon are of particular interest due to their important 'catapult-like' function during efficient and healthy human locomotion. In this study, we examined age-related differences in the in vivo mechanical properties of both muscle and tendon in the human ankle plantarflexors in healthy younger (21 ± 3.25 years) and older (69 ± 2.86 years) adults. All participants were physically active, to represent healthy ageing. B-mode ultrasound coupled with force measurements was used to determine in vivo Achilles tendon stiffness and shear-wave elastography was used to measure shear modulus, an index of muscle stiffness, in the medial and lateral gastrocnemii. We found that older adults displayed 43% lower (p = 0.004) Achilles tendon stiffness, 59% lower (p < 0.001) Achilles tendon Young's modulus, and 34% greater (p = 0.002) Achilles tendon cross-sectional area compared to younger participants. We found no difference in the shear modulus of the medial or lateral gastrocnemii between the younger and older individuals. The reduction in Achilles tendon stiffness coupled with similar gastrocnemii muscle shear modulus likely influences the integrated neuromechanical function of the ankle plantarflexor muscle-tendon units during locomotor tasks. Further investigations into the relationship between altered mechanical properties and in vivo muscle-tendon dynamics will provide greater insights into the age-related declines in mobility and locomotor function.
Muscle contributions to maximal single-leg forward braking and backward acceleration in elite athletes.
Venue: Journal of biomechanics

Abrupt deceleration is a common practice in several sports, where sudden changes of direction are needed to reach the highest performance level. When inappropriately performed, these actions can impose excessive mechanical loads at the lower limb joints, specifically at the knee and ankle joints, usually associated with increased risk of injury. This work aims to estimate muscle forces and muscle contributions to the acceleration of the center of mass during a rapid maximal single-leg forward braking and backward acceleration task. Fourteen elite male injury-free indoor-sports athletes participated in this work. Scaled generic musculoskeletal models, consisting of 12 segments, 23 degrees of freedom, and 92 muscle-tendon actuators were used in OpenSim software. Due to the nature of the musculoskeletal system, all muscles are considered when joint and segment positions, velocities, and accelerations are calculated, resulting in muscles acting to accelerate joints it does not span. The knowledge of muscle interaction during this multijoint task is important and was achieved through an induced acceleration analysis. The vasti (-9.18 ± 2.09 and -7.63 ± 1.33 N/Kg) were the main contributors to the centre of mass deceleration profile along the anterior/posterior direction, aided by the soleus muscle (9.72 ± 2.35 and 9.62 ± 2.07 N/Kg), which counteracted most of the effects applied by gravity along the vertical direction, during both phases. This study provides a computational approach to quantify the dynamical interactions between muscles and joints during an abrupt anterior/posterior deceleration task, thus giving robust and insightful indicators that can be implemented in injury prevention protocols.
Muscle size-scaled shear elastic modulus: A muscle force index independent of maximal voluntary contraction, assessed during elbow extension.
Venue: Journal of biomechanics

Shear elastic modulus (G) can differ among individuals due to muscle size and other factors, even for constant muscle force. Inter-individual comparisons of G usually require normalization by maximal voluntary contraction (MVC), but MVC procedures may not be appropriate for certain clinical populations including those presenting with pain or other compromised functionality. This study aimed to test whether muscle size-scaled G, which does not require MVC testing, would yield stronger correlation with absolute torque than unscaled G. Twelve-healthy males performed isometric elbow extension across a range of torque magnitudes (from 5 Nm until 60% MVC). G of the triceps brachii was measured using shear wave elastography during each trial. Cross-sectional area (CSA) and muscle thickness (MT) of the triceps brachii were measured at rest. Scaled G was calculated as a product of G and CSA or MT ("G-CSA" and "G-MT", respectively). Within-individual linear regressions were conducted between absolute torque and the three force indicator variables. The regression slopes' coefficient of variation (CV) was calculated for each indicator across individuals. Between-individual correlation coefficients were calculated, after pooling all data across individuals into a single regression analysis for each indicator. Linear regression found that inter-individual slope variation increased in the following order: G-CSA, G-MT, and unscaled G (CV = 0.15, 0.18, and 0.29, respectively). Pooled-individual correlation coefficients were significantly higher in G-CSA and G-MT than in unscaled G (r = 0.948, 0.924, and r = 0.783, respectively). These results suggest that muscle size-scaled G may be more appropriate than unscaled G when comparing shear moduli across individuals.
Head stabilization during standing in people with persisting symptoms after mild traumatic brain injury.
Venue: Journal of biomechanics

Increased postural sway is often observed in people with mild traumatic brain injury (mTBI), but our understanding of how individuals with mTBI control their head during stance is limited. The purpose of this study was to determine if people with mTBI exhibit increased sway at the head compared with healthy controls. People with persisting symptoms after mTBI (n = 59, 41 women) and control participants (n = 63, 38 women) stood quietly for one minute in four conditions: eyes open on a firm surface (EO-firm), eyes closed on a firm surface (EC-firm), eyes open on a foam pad (EO-foam), and eyes closed on foam (EC-foam). Inertial sensors at the head, sternum, and lumbar region collected tri-axial accelerations. Root-mean-square (RMS) accelerations in anteroposterior (AP) and mediolateral (ML) directions and sway ratios between the head and sternum, head and lumbar, and sternum and lumbar region were compared between groups. Temporal coupling of anti-phase motion between the upper and lower body angular accelerations was assessed with magnitude squared coherence and cross-spectral phase angles. People with mTBI demonstrated greater sway than controls across conditions and directions. During foam-surface conditions, the control group, but not the mTBI group, reduced ML sway at their head and trunk relative to their lumbar by increasing the expression of an anti-phase hip strategy within the frontal plane. These results are consistent with suggestions of inflexible or inappropriate postural control in people with mTBI.
The influence of microstructure on crack propagation in cortical bone at the mesoscale.
Venue: Journal of biomechanics

The microstructure of cortical bone is key for the tissue's high toughness and strength and efficient toughening mechanisms have been identified at the microscale, for example when propagating cracks interact with the osteonal microstructure. Finite element models have been proposed as suitable tools for analyzing the complex link between the local tissue structure and the fracture resistance of cortical bone. However, previous models that could capture realistic crack paths in cortical bone were due to the required computational effort limited to idealized osteon geometries and small (<1 mm2) model domains. The objective of this study was therefore to bridge the gap between experimental and numerical analysis of crack propagation in cortical bone by introducing image-based models at the mesoscale. Tissue orientation maps from high-resolution micro-CT images were used to define the distribution and orientation of weak interfaces in the models. Crack propagation was simulated using the extended finite element method in combination with an interface damage model, previously developed to simulate crack propagation in microstructural osteon models. The results showed that image-based mesoscale models can be used to capture interactions between cracks and microstructure. The simulated crack paths predicted the general trends seen in experiments with more irregular patterns for cracks propagating perpendicular compared to parallel to the osteon orientation. In all, the proposed method enabled an efficient description of the tissue level microstructure, which is a necessity to predict realistic crack paths in cortical bone and is an important step towards simulating crack propagation in bone models in 3D.
Principles of a 3D printed mechanical device for total knee balancing.
Venue: Journal of biomechanics

Implant alignment and soft-tissue balancing are important factors in total knee arthroplasty (TKA). The purpose of this study was to design a mechanical balancing device, which measures deflections resulting from forces applied on each condyle to provide numerical data indicating the extent of ligament release needed, or angular changes in the bone cuts required to achieve a balanced knee. Two mechanical devices were designed and 3D printed, Pistol Grip and In-line. The Pistol Grip design consisted of a lever system that indicated the difference between lateral and medial forces with a single pointer. The In-line design allows for the quantification of the absolute force applied on each individual condyle. The two designs were evaluated on a test rig designed to model balance and imbalance conditions in the knee. For the Pistol Grip design maximum pointer deflection indicates a 2 mm change in elevation per condyle and/or a 3 degrees angular change of the condyles which can be corrected by adjusting the ligament lengths equivalent to 2 mm and/or by modifying the proximal or distal femur bone cut by 3 degrees. For the In-line design, maximum pointer deflection represented a 40 N load on the condyle. Our mechanical balancer designs were successful in providing information that can guide surgeons to accurately achieve balance through ligamentous releases and/or modification to bone cuts. The balancer designs are easy to use, do not require any electronics or software, and can be incorporated into the surgical procedure.
Differences in stretch-shortening cycle and residual force enhancement between muscles.
Venue: Journal of biomechanics

It has been suggested that cross bridge kinetics and residual force enhancement (RFE) affect force in the stretch-shortening cycle (SSC). Because cross bridge kinetics and titin isoforms, which are thought to be related to RFE, differ between muscles, the SSC effect may be also muscle-dependent. Thus, we compared the SSC effect between psoas and soleus muscles, which have a distinct fiber type distribution and different titin isoforms. Four tests (SSC, SSC control, RFE, RFE control) were conducted using isolated, skinned fibers of psoas and soleus. In the SSC tests, fibers were activated at an average sarcomere length of 2.4 μm, stretched to 3.0 μm, and shortened to 2.4 μm. In the SSC control tests, fibers were activated at an average sarcomere length of 3.0 μm and then shortened to 2.4 μm. The relative increase in mechanical work obtained during shortening between tests was defined as the SSC effect. In the RFE tests, fibers were activated at an average sarcomere length of 2.4 μm and then stretched to 3.0 μm, while the RFE control tests consisted of an isometric contraction at 3.0 μm. The difference in steady-state isometric force between tests was defined as RFE. The SSC effect was greater in soleus than in psoas, while the RFE was the same for both muscles. Since the SSC effect was greater in soleus, while the RFE was the same, the observed greater SSC effect is probably not directly caused by RFE, but may be related to differences in cross bridge kinetics.
Between-session reliability of subject-specific musculoskeletal models of the spine derived from optoelectronic motion capture data.
Venue: Journal of biomechanics

This study evaluated the between-session reliability of creating subject-specific musculoskeletal models with optoelectronic motion capture data, and using them to estimate spine loading. Nineteen healthy participants aged 24-74 years underwent the same set of measurements on two separate occasions. Retroreflective markers were placed on anatomical regions, including C7, T1, T4, T5, T8, T9, T12 and L1 spinous processes, pelvis, upper and lower limbs, and head. We created full-body musculoskeletal models with detailed thoracolumbar spines, and scaled these to create subject-specific models for each individual and each session. Models were scaled from distances between markers, and spine curvature was adjusted according to marker-estimated measurements. Using these models, we estimated vertebral compressive loading for five different standardized postures: neutral standing, 45˚ trunk flexion, 15˚ trunk extension, 20˚ lateral bend to the right, and 45˚ axial rotation to the right. Intraclass correlation coefficients (ICCs) and standard error of measurement were calculated as measures of between-session reliability and measurement error, respectively. Spine curvature measures showed excellent reliability (ICC = 0.79-0.91) and body scaling segments showed fair to excellent reliability (ICC = 0.46-0.95). We found that musculoskeletal models showed mostly excellent between-session reliability to estimate spine loading, with 91% of ICC values > 0.75 for all activities. This information is a necessary precursor for using motion capture data to estimate spine loading from subject-specific musculoskeletal models, and suggests that marker data will deliver reproducible subject-specific models and estimates of spine loading.
An experimental evaluation of a concept to improve conventional aortic prostheses.
Venue: Journal of biomechanics

Conventionally used textile prosthesis for traditional open surgical repair (OSR) of aortic aneurysms have a lower compliance than the native aortic tissue. Graft placements lead to an acute drop in compliance which effects cardiovascular risk and the development of graft related complications. A custom-made spring casing was applied to a Dacron graft segment under physiological pressure conditions within a five-element biventricular mock circulation loop, to investigate experimentally a concept to improve the compliance of a conventional aortic prosthesis by changing the transverse graft cross-section. Two different prosthesis locations, proximal and distal of compliant silicone tubing were used to study uniaxial graft compression with an elastic device. To characterise the devices' performance by means of pulse pressure (PP), diastolic pressure (Pdia) and pulse wave velocity(PWV), fluid pressures and flow were recorded. In a proximal graft setting (ascending aorta repair) elastic uniaxial compression with a custom-made spring casing (2 cm width) could significantly reduce PP by 10-14% (p < .001) and slowed PWV from 6.7 to 5.2 m/s (22%, p = .002). Applied to a graft in a distal position, the spring casing demonstrated less impact on PP (2-10%), but significantly reduced PWV in this mock aorta segment from 13.7 to 5.5 m/s (60%, p = .004). In conclusion, a newly conceptualised spring casing applied to the external wall of synthetic aortic grafts can reduce PP and slow PWV. By restoring elastic aortic recoil in stiff textile aortic prostheses, the presented concept is a potential solution to improve long-term aortic prosthesis related complications.
Effect of angular velocity on active muscle stiffness in vivo.
Venue: Journal of biomechanics

We previously reported that active muscle stiffness could be evaluated in vivo. However, we were not able to investigate active muscle stiffness as more than 250 deg·s-1 due to the limitation of the torque motor of dynamometer. The aim of the present study was to investigate the effect of angular velocities (including higher angular velocities of more than 250 deg·s-1) on active muscle stiffness. Eighteen males volunteered for this study. Active muscle stiffness of the medial gastrocnemius muscle was calculated according to changes in the estimated muscle force and fascicle length during fast lengthening at five different angular velocities (100, 200, 300, 500, and 600 deg·s-1). Electromyographic activities of the lateral gastrocnemius muscle (LG) and soleus muscle (SOL) were evaluated over two different phases: before the stretch (mEMGa) and after the stretch (mMEGb). Active muscle stiffness was higher at 300 than at 100 deg·s-1, but decreased as the angular velocity increased from 300 to 600 deg·s-1. There were no differences in mEMGa and mEMGb values among the five angular velocities, whereas mEMGb values were higher than mEMGa for all angular velocities. In conclusion, active muscle stiffness was highest at 300 deg·s-1 and decreased at both slower and faster angular velocities.
Modulation of physiological cross-sectional area and fascicle length of vastus lateralis muscle in response to eccentric exercise.
Venue: Journal of biomechanics

In the current study, we investigated the effect of lengthening velocity during eccentric exercise on the modulation of the physiological cross-sectional area (PCSA) and fascicle length of the vastus lateralis (VL) muscle. We hypothesized a greater increase in muscle PCSA after training with lower lengthening velocities and a greater increase in fascicle length after higher lengthening velocities. Forty-seven young men were randomly assigned to either a control (n = 14) or an intervention group (n = 33). The participants of the intervention group were randomly allocated to one of four isokinetic eccentric training protocols of the knee extensors, with four different knee angular velocities (45°/s, 120°/s, 210°/s and 300°/s), yet similar range of motion (25-100° knee joint angle), load magnitude (100% of isometric maximum) and load volume (i.e. similar time under tension for one training set). Before and after an 11-week training period with 3 times per week exercise, muscle volume, pennation angle, fascicle length and PCSA of the VL muscle were measured using magnetic resonance imaging and ultrasonography. After the training, the VL muscle volume and fascicle length increased similarly and approximately 5% in all investigated protocols. The PCSA and pennation angles of the VL did not change after any exercise protocol, indicating negligible radial muscle adaptation after the training. The reason for the found hypertrophy of VL muscle after eccentric training in a wide range of lengthening velocities was mainly a longitudinal muscle growth. Further, the longitudinal muscle growth was independent of the lengthening velocity.
Measurement of normal and pathological mandibular and temporomandibular joint kinematics: A systematic review.
Venue: Journal of biomechanics

Motion of the mandible and temporomandibular joint (TMJ) plays a pivotal role in the function of the dentition and associated hard and soft tissue structures, and facilitates mastication, oral communication and access to respiratory and digestive systems. Quantification of TMJ kinematics is clinically relevant in cases of prosthetic rehabilitations, TMJ disorders, osteoarthritis, trauma, tumour resection and congenital abnormalities, which are known to directly influence mandibular motion and loading. The objective of this systematic review was to critically investigate published literature on historic and contemporary measurement modalities used to quantify in vivo mandibular and TMJ kinematics in six degrees of freedom. The electronic databases of Scopus, Web of Science, Medline, Embase and Central were searched and 109 relevant articles identified. Publication quality was documented using a modified Downs and Black checklist. Axiography and ultrasonic tracking are commonly employed in the clinical setting due to their simplicity and capacity to rapidly acquire low-fidelity mandibular motion data. Magnetic and optoelectronic tracking have been used in combination with dental splints to produce higher accuracy measurements while minimising skin motion artefact, but at the expense of setup time and cost. Four-dimensional computed tomography provides direct 3D measurement of mandibular and TMJ motion while circumventing skin motion artefact entirely, but employs ionising radiation, is restricted to low sampling frequencies, and requires time-consuming image processing. Recent advances in magnetic tracking using miniature sensors adhered to the teeth in combination with intraoral scanning may facilitate rapid and high precision mandibular kinematics measurement in the clinical setting. The findings of this review will guide selection and application of mandibular and TMJ kinematic measurement for both clinical and research applications.