nils-herrmann/clean_scirepeval huggingface dataset:
Axial pelvis range of motion affects thorax-pelvis timing during gait.
Venue: Journal of biomechanics

During gait, patients with pelvic girdle pain and low back pain demonstrate an altered phase relationship between axial thorax and pelvis rotations (thorax-pelvis relative phase). This could be the result of an increase in axial pelvis range of motion (ROM) which has been observed in these patients as well. To establish this relationship, we investigated if altered axial pelvis ROM during gait affects thorax-pelvis relative phase in 12 healthy subjects. These subjects walked on a treadmill and received real-time feedback on axial pelvis rotations. Subjects were asked to (1) walk normal, and walk with (2) decreased and (3) increased pelvis ROM. Gait speed and stride frequency were matched between trials. Subjects were able to increase pelvis ROM to a large extent, but the reduction in pelvis ROM was relatively small. Walking with large pelvis ROM resulted in a change in thorax-pelvis relative phase similar to that in pelvic girdle pain and low back pain. A forward dynamic model was used to predict the effect of manipulation of pelvis ROM on timing of thorax rotations independent of apparent axial trunk stiffness and arm swing amplitude (which can both affect thorax-pelvis relative phase). The model predicted a similar, even larger, effect of large axial pelvis ROM on thorax-pelvis relative phase, as observed experimentally. We conclude that walking with actively increased ROM of axial pelvis rotations in healthy subjects is associated with a shift in thorax-pelvis relative phase, similar to observations in patients with pelvic girdle pain and low back pain.
Computationally efficient modelling of hip replacement separation due to small mismatches in component centres of rotation.
Venue: Journal of biomechanics

Patient imaging and explant analysis has shown evidence of edge loading of hard-on-hard hip replacements in vivo. Experimental hip simulator testing under edge loading conditions has produced increased, clinically-relevant, wear rates for hard-on-hard bearings when compared to concentric conditions. Such testing, however, is time consuming and costly. A quick running computational edge loading model (Python Edge Loading (PyEL) - quasi-static, rigid, frictionless), capable of considering realistic bearing geometries, was developed. The aim of this study was to produce predictions of separation within the typical experimental measurement error of ∼0.5 mm. The model was verified and validated against comparable finite element (FE) models (including inertia and friction) and pre-existing experimental test data for 56 cases, covering a variety of simulated cup orientations, positions, tissue tensions, and loading environments. The PyEL model agreed well with both the more complex computational modelling and experimental results. From comparison with the FE models, the assumption of no inertia had little effect on the maximum separation prediction. With high contact force cases, the assumption of no friction had a larger effect (up to ∼5% error). The PyEL model was able to predict the experimental maximum separations within ∼0.3 mm. It could therefore be used to optimise an experimental test plan and efficiently investigate a much wider range of scenarios and variables. It could also help explain trends and damage modes seen in experimental testing through identifying the contact locations on the liner that are not easily measured experimentally.
Skeletal kinematics of the midtarsal joint during walking: Midtarsal joint locking revisited.
Venue: Journal of biomechanics

The kinematics of the human foot complex have been investigated to understand the weight bearing mechanism of the foot. This study aims to investigate midtarsal joint locking during walking by noninvasively measuring the movements of foot bones using a high-speed bi-planar fluoroscopic system. Eighteen healthy subjects volunteered for the study; the subjects underwent computed tomography imaging and bi-planar radiographs of the foot in order to measure the three-dimensional (3D) midtarsal joint kinematics using a 2D-to-3D registration method and anatomical coordinate system in each bone. The relative movements on bone surfaces were also calculated in the talonavicular and calcaneocuboid joints and quantified as surface relative velocity vectors on articular surfaces to understand the kinematic interactions in the midtarsal joint. The midtarsal joint performed a coupled motion in the early stance to pronate the foot to extreme pose in the range of motion during walking and maintained this pose during the mid-stance. In the terminal stance, the talonavicular joint performed plantar-flexion, inversion, and internal rotation while the calcaneocuboid joint performed mainly inversion. The midtarsal joint moved towards an extreme supinated pose, rather than a minimum motion in the terminal stance. The study provides a new perspective to understand the kinematics and kinetics of the movement of foot bones and so-called midtarsal joint locking, during walking. The midtarsal joint continuously moved towards extreme poses together with the activation of muscle forces, which would support the foot for more effective force transfer during push-off in the terminal stance.
Regional variations of in vivo surface stiffness of soft tissue layers of musculoskeletal extremities.
Venue: Journal of biomechanics

Surface stiffness of bulk soft tissue in musculoskeletal extremities is important to consider in the design of prosthetics, exoskeletons, and protective gear. This knowledge is also foundational for surgical simulation and clinical interventions leveraging manipulation of the musculoskeletal surfaces. Injuries to musculoskeletal extremities are common and surgical and preventive interventions require interactions between various objects such as surgical tools and support surfaces with tissue boundaries. While a handful of investigations examined the variations in indentation mechanics due to pathology or injury specific sites, a comprehensive analysis across the surfaces of musculoskeletal extremities has not been completed. In this study we examine variations of surface stiffness across 8 sites of the upper and lower arms and legs for 95 subjects using an instrumented ultrasound device. Differences in surface stiffness were observed between gender, activity level, and indentation location groups. The lower arm posterior location had the highest average stiffness (3.89 × 10-3 MPa/mm), while the lowest stiffness was observed at the upper leg posterior location (0.98 × 10-3 MPa/mm). The differences between indentation sites were larger in magnitude when compared to differences due to demographics (gender and activity level). However the large ranges of the 95% confidence intervals suggest that an aggregated metric based on population or sub-group may not capture individual variations. This study implicates the motivation to explore tissue composition variations within the indentation sites as well as the potential importance to include variations in surface stiffness during surgical simulations.
In search of sports biomechanics' holy grail: Can athlete-specific optimum sports techniques be identified?
Venue: Journal of biomechanics

The development of methods that can identify athlete-specific optimum sports techniques-arguably the holy grail of sports biomechanics-is one of the greatest challenges for researchers in the field. This 'perspectives article' critically examines, from a dynamical systems theoretical standpoint, the claim that athlete-specific optimum sports techniques can be identified through biomechanical optimisation modelling. To identify athlete-specific optimum sports techniques, dynamical systems theory suggests that a representative set of organismic constraints, along with their non-linear characteristics, needs to be identified and incorporated into the mathematical model of the athlete. However, whether the athlete will be able to adopt, and reliably reproduce, his/her predicted optimum technique will largely be dependent on his/her intrinsic dynamics. If the attractor valley corresponding to the existing technique is deep, or if the attractor valleys corresponding to the existing technique and the predicted optimum technique are in different topographical regions of the dynamic landscape, technical modifications may be challenging or impossible to reliably implement even after extended practice. The attractor layout defining the intrinsic dynamics of the athlete, therefore, needs to be determined to establish the likelihood of the predicted optimum technique being reliably attainable by the athlete. Given the limited set of organismic constraints typically used in mathematical models of athletes, combined with the methodological challenges associated with mapping the attractor layout of an athlete, it seems unlikely that athlete-specific optimum sports techniques will be identifiable through biomechanical optimisation modelling for the majority of sports skills in the near future.
A biomechanical study of the relationship between running velocity and three-dimensional lumbosacral kinetics.
Venue: Journal of biomechanics

Faster running is not performed with proportional increase in all joint torque/work exertions. Although previous studies have investigated lumbopelvic kinetics for a single velocity, it is unclear whether each lumbopelvic torque should increase for faster running. We examined the relationship between running velocity and lumbopelvic kinetics. We calculated the three-dimensional lumbosacral kinetics of 10 male sprinters during steady-state running on a temporary indoor running track at five target velocities: 3.0 (3.20 ± 0.16), 4.5 (4.38 ± 0.18), 6.0 (5.69 ± 0.47), 7.5 (7.30 ± 0.41), and maximal sprinting (9.27 ± 0.36 m/s). The lumbosacral axial rotation torque increased more markedly (from 0.37 ± 0.06 to 1.99 ± 0.46 Nm/kg) than the extension and lateral flexion torques. The increase in the axial rotation torque was larger above 7.30 m/s. Conversely, the extension and lateral flexion torques plateaued when running velocity increased above 7.30 m/s. Similar results were observed for mechanical work. The results indicate that faster running required larger lumbosacral axial rotation torque. Conversely, the extension and lateral flexion torques were relatively invariant to running velocity above 7 m/s, implying that faster running below 7 m/s might increase the biomechanical loads causing excessive pelvic posterior tilt and excessive pelvic drop which has the potential to cause pain/injury related to lumbopelvic extensors and lateral flexors, whereas these biomechanical loads might not relate with running velocity above 7 m/s.
Biomechanical model of swimming rehabilitation after hip and knee surgery.
Venue: Journal of biomechanics

As a low-to-moderate intensity rehabilitation exercise after hip and knee surgery, we propose a dynamical model of the legs motion through the water medium in freestyle and backstroke swimming. We formulate a general Kirchhoff-Lagrangian dynamics model of the legs-propulsion through the water in post-surgical rehabilitation swimming. We start by defining the two-leg-propulsion configuration manifold. This is composed of eight Euclidean groups of rigid motions in 3D space for each of the four leg segments. Next, we define Newton-Euler dynamics for each segment. This single segmental dynamics is further generalized into Lagrangian dynamics for the whole leg-propulsion system. Finally, the water effects are added in the form of Kirchhoff's vector cross-products. In agreement with orthopaedic recommendations for post-surgical rehabilitation, numerical simulation is performed on a simplified version of the full Kirchhoff-Lagrangian dynamics model, which we call the "robotic swimming leg" - with intentionally reduced number of (microscopic, non-sagittal) degrees-of-freedom. The purpose of this development is both qualitative, for medical and physiotherapist practitioners to study, and quantitative, for biomechanics experts to analyze and further develop.
A prospective study of lumbo-pelvic coordination in patients with non-chronic low back pain.
Venue: Journal of biomechanics

Despite the current knowledge about abnormalities in the lumbo-pelvic coordination of patients with non-specific low back pain (LBP), it is unclear how such abnormalities change with time. Timing and magnitude aspects of lumbo-pelvic coordination during a trunk forward bending and backward return task along with subjective measures of pain and disability were collected at three-time points over a six-month period from 29 patients who had non-chronic LBP at the time of enrollment in the study. To enable investigation of abnormalities in lumbo-pelvic coordination of patients, we also included lumbo-pelvic coordination data of age and gender-matched back healthy individuals from an earlier study of our group. Finally, differences in lumbo-pelvic coordination between patients with moderate-severe LBP (i.e., those whose level of pain was ≥ 4 (out of 10) at all three data collection sessions; n = 8) and patients with low-moderate LBP (n = 21) were investigated. There were clear distinctions in measures of lumbo-pelvic coordination between patients with low-moderate and moderate-severe LBP. Contrary to our expectation, however, the abnormalities in magnitude aspects of lumbo-pelvic coordination were larger (F > 4.84, P < 0.012) in patients with low-moderate LBP. These abnormalities in patients with low-moderate LBP, compared to controls, included larger (>12°) pelvic and thoracic rotations as well as smaller (>10°) lumbar flexion. The abnormal lumbo-pelvic coordination of patients with non-specific LBP, observed at baseline, persisted (F < 1.96, P > 0.156) or worsen (F > 3.48, P < 0.04) over the course of study period despite significant improvement in their pain (18% decrease; F = 12.10, P < 0.001) and disability (10% decrease; F = 4.39, P = 0.017). Distinct but lingering abnormalities in lumbo-pelvic coordination, observed in patients with low-moderate and moderate-severe LBP, might have a role in persistence and/or relapse of symptoms in patients with non-specific LBP. Such inferences, however, should further be studied in future via investigation of the relationship between abnormalities in lumbo-pelvic coordination and clinical presentation of LBP.
Microstructure, mineral and mechanical properties of teleost intermuscular bones.
Venue: Journal of biomechanics

There is an increasing interest in understanding teleost bone biomechanics in several scientific communities, for instance as interesting biomaterials with specific structure-function relationships. Intermuscular bones of teleost fish have previously been described to play a role in the mechanical force transmission between muscle and bone, but their biomechanical properties are not yet fully described. Here, we have investigated intermuscular bones (IBs) of the North Atlantic Herring with regard to their structure and micro-architecture, mineral-related properties, and micro-mechanical tensile properties. A total of 115 IBs from 18 fish were investigated. One cohort of IBs, containing 20 bones from 2 smaller fish and 23 bones of 3 larger fish, was used for mechanical testing, wide-angle X-ray scattering, and scanning electron microscopy. Another cohort, containing 36 bones from 7 smaller fish and 36 bones from 6 larger fish, was used for microCT. Results show some astonishing properties of the IBs: (i) IBs present higher ductility, lower Young's modulus but similar strength and TMD (Tissue Mineral Density) compared to mammalian bone, and (ii) IBs from small fish were 49% higher in Young's modulus than fish bones from larger fish while their TMD was not statistically different and crystal length was 8% higher in large fish bones. Our results revealed that teleost IB presents a hybrid nature of soft and hard tissue that differs from other bone types, which might be associated with their evolution from mineralized tendons. This study provides new data regarding teleost fish bone biomechanical and micro-structural properties.
Effect of variable periodontal ligament thickness and its non-linear material properties on the location of a tooth's centre of resistance.
Venue: Journal of biomechanics

In orthodontics, the 3D translational and rotational movement of a tooth is determined by the force-moment system applied and the location of the tooth's centre of resistance (CR). Because of the practical constraints of in-vivo experiments, the finite element (FE) method is commonly used to determine the CR. The objective of this study was to investigate the geometric model details required for accurate CR determination, and the effect of material non-linearity of the periodontal ligament (PDL). A FE model of a human lower canine derived from a high-resolution µCT scan (voxel size: 50 µm) was investigated by applying four different modelling approaches to the PDL. These comprised linear and non-linear material models, each with uniform and realistic PDL thickness. The CR locations determined for the four model configurations were in the range 37.2-45.3% (alveolar margin: 0%; root apex: 100%). We observed that a non-linear material model introduces load-dependent results that are dominated by the PDL regions under tension. Load variation within the range used in clinical orthodontic practice resulted in CR variations below 0.3%. Furthermore, the individualized realistic PDL geometry shifted the CR towards the alveolar margin by 2.3% and 2.8% on average for the linear and non-linear material models, respectively. We concluded that for conventional clinical therapy and the generation of representative reference data, the least sophisticated modelling approach with linear material behaviour and uniform PDL thickness appears sufficiently accurate. Research applications that require more precise treatment monitoring and planning may, however, benefit from the more accurate results obtained from the non-linear constitutive law and individualized realistic PDL geometry.
Development of a finite element musculoskeletal model with the ability to predict contractions of three-dimensional muscles.
Venue: Journal of biomechanics

Representation of realistic muscle geometries is needed for systematic biomechanical simulation of musculoskeletal systems. Most of the previous musculoskeletal models are based on multibody dynamics simulation with muscles simplified as one-dimensional (1D) line-segments without accounting for the large muscle attachment areas, spatial fibre alignment within muscles and contact and wrapping between muscles and surrounding tissues. In previous musculoskeletal models with three-dimensional (3D) muscles, contractions of muscles were among the inputs rather than calculated, which hampers the predictive capability of these models. To address these issues, a finite element musculoskeletal model with the ability to predict contractions of 3D muscles was developed. Muscles with realistic 3D geometry, spatial muscle fibre alignment and muscle-muscle and muscle-bone interactions were accounted for. Active contractile stresses of the 3D muscles were determined through an efficient optimization approach based on the measured kinematics of the lower extremity and ground force during gait. This model also provided stresses and strains of muscles and contact mechanics of the muscle-muscle and muscle-bone interactions. The total contact force of the knee predicted by the model corresponded well to the in vivo measurement. Contact and wrapping between muscles and surrounding tissues were evident, demonstrating the need to consider 3D contact models of muscles. This modelling framework serves as the methodological basis for developing musculoskeletal modelling systems in finite element method incorporating 3D deformable contact models of muscles, joints, ligaments and bones.
Quantification of regional right ventricular strain in healthy rats using 3D spiral cine dense MRI.
Venue: Journal of biomechanics

Statistical data from clinical studies suggests that right ventricular (RV) circumferential strain (Ecc) and longitudinal strain (Ell) are significant biomarkers for many cardiovascular diseases. However, a detailed and regional characterization of these strains in the RV is very limited. In the current study, RV images were obtained with 3D spiral cine DENSE MRI in healthy rats. An algorithm for surface growing was proposed in order to fit irregular topology. Specifically, a new custom plugin for the DENSEanalysis program, called 3D DENSE Plugin for Crescent Organ, was developed for surface reconstruction and precise segmentation of organs with sharp curvature, such as the murine RV. The RV free wall (RVFW) was divided into three longitudinal thirds (i.e., basal, middle, and apical) with each one partitioned into circumferential fourths (i.e., anterior, anteriorlateral, inferiorlateral and inferior). Peak systolic strains were quantified for each segment and comparisons were performed statistically. The inclusion of a new plugin was able to generate global values for Ecc and Ell that are in good agreement with previous findings using MRI. Despite no regional variation found in the peak Ecc, the peak Ell exhibited regional variation at the anterior side of the RV, which is potentially due to differences in biventricular torsion at the RV insertion point and fiber architecture. These results provide fundamental insights into the regional contractile function of the RV in healthy rat and could act as a normative baseline for future studies on regional changes induced by disease or treatment.
Strong independent associations between gait biomechanics and pain in patients with knee osteoarthritis.
Venue: Journal of biomechanics

We investigated the simple and multivariate associations between knee pain and gait biomechanics. 279 patients with medial knee osteoarthritis (OA) and discordant changes in pain between limbs after walking completed bilateral three-dimensional gait analysis. For each limb, patients rated their pain before and after a 6-min walk and the change in pain was recorded as an increase (≥1 points) or not (≤0 points). Among paired limbs, the simple and multivariate associations between an increase in pain and the external moments in each orthogonal plane were evaluated using conditional logistic regression. The analyses were then repeated for knee angles. Univariate analyses demonstrated associations in each plane that varied in both magnitude and direction, with larger associations for the knee moments [Odds Ratio (95% confidence interval) = first peak adduction moment: 2.80 (2.02, 3.88), second peak adduction moment: 2.36 (1.73, 3.24), adduction impulse: 6.65 (3.50, 12.62), flexion moment: 0.46 (0.36, 0.60), extension moment: 0.56 (0.44, 0.71), internal rotation moment: 7.54 (3.32, 17.13), external rotation moment: 0.001 (0.00, 0.04)]. Multivariate analyses with backward elimination resulted in a model including only the adduction impulse [5.35 (2.51, 11.42)], flexion moment [0.32 (0.22, 0.46)] and extension moment [0.28 (0.19, 0.42)]. The varus, flexion and extension angles were included in the final multivariate model for the knee angles. When between-person confounding is lessened by comparing limbs within patients, there are strong independent associations between knee pain and multiple external knee moments that vary in magnitude and direction. While controlling for other knee moments, a greater adduction impulse and lower flexion and extension moments were independently associated with greater odds of an increase in pain.