nils-herrmann/clean_scirepeval huggingface dataset:
The effect of simulated marker misplacement on the interpretation of inter-limb differences during a change of direction task.
Venue: Journal of biomechanics

The objective assessment of biomechanical asymmetries during movement tasks is used to monitor rehabilitation following anterior cruciate ligament reconstruction (ACLR). Marker placement is an important source of methodological variability within human motion analysis. It is currently unclear how marker placement error effects the interpretation of biomechanical asymmetries throughout post ACLR rehabilitation. The aim of this investigation was to determine the effect of random marker placement variation on the interpretation of inter-limb differences during a change of direction (CoD) task. Forty-seven participants 9 months post-ACLR and fifty uninjured controls completed a 90° CoD task on both limbs. Inter-limb differences in kinematic and kinetic metrics during the CoD stance phase were calculated for both groups using the Vicon Plug-in Gait model, and ACLR subjects were classified as having 'normal' or 'abnormal' inter-limb differences relative to the control group. Simulated random marker displacements based on published marker placement error ranges were then repeatedly applied to the lateral thigh, femoral epicondyle and tibia markers. ACLR inter-limb differences were recalculated each time, allowing the estimation of 95% confidence intervals and minimal identifiable between-session changes. ACLR subjects were also reclassified relative to the control group after each simulation and the percentage of participants to change classification was calculated. Marker displacements caused large deviations in inter-limb difference measures in several variables including hip rotation angle, knee abduction angle and knee abduction moment, thus limiting the ability to identify participants with large inter-limb differences relative to a control group. These findings highlight the challenges in using marker-based biomechanical models to conduct objective assessments of inter-limb differences during CoD tasks.
Towards the non-invasive determination of arterial wall distensible properties: New approach using old formulae.
Venue: Journal of biomechanics

Arterial function and wall mechanical properties are important determinants of hemodynamics in the circulation. However, their non-invasive determination is not widely available. Therefore, the aim of this work is to present a novel approach for the non-invasive determination of vessel's distensibility and elastic modulus. Simultaneous measurements of vessel's Diameter (D) and flow velocity (U) were recorded to determine local wave speed (nC) in flexible tubes and calf aortas non-invasively using the lnDU-loop method, which was used to calculate the Distensibility (nDs) and Elastic Modulus (nE), also non-invasively. To validate the new approach, the non-invasive results were compared to traditionally invasive measurements of Dynamic Distensibility (Dsd) and Tangential Elastic Modulus (Em). In flexible tubes, the average nDs was higher and nE was lower than Dsd and Em by 1.6% and 6.9%, respectively. In calf aortas, the results of nDs and nE agreed well with those of Dsd and Em, as demonstrated by Bland-Altman technique. The results of nDs and nE are comparable to those determined using traditional techniques. Our results suggest that nDs and nE could be measured in-vivo non-invasively, given the possibility of measuring D and U to obtain nC. Further studies are warranted to establish the clinical usefulness of the new approach.
Exposure to brain trauma in six age divisions of minor ice hockey.
Venue: Journal of biomechanics

Acute and chronic neurological risks associated with brain trauma sustained in professional ice hockey has generated concern for youth participants. Minor hockey is a different game when compared to elite players presenting distinctive risk factors for each age division. Objective measures of brain trauma exposure were documented for six divisions in minor ice hockey; U7, U9, U11, U13, U15, U18. Game video analysis, physical reconstruction and computational modelling was employed to capture the event conditions, frequency of impacts, frequency of high strain magnitude (>0.17) impacts, and cumulative trauma. The results showed proportional differences in the event conditions; event type, closing velocity, and head impact location, informing the improvement of age appropriate protection, testing protocols, and safety standards. Frequency of events were highest for U7 when players were learning to skate, and again in U18 as game physicality increases. No significant difference was observed in frequency of high magnitude impacts across age divisions. A peak in high magnitude impacts was empirically observed at both U7 and U15 where skill development in skating and body checking, respectively, were most prominent. Finally, a cumulative trauma metric incorporating frequency and magnitude of impacts provided a detailed analysis of trauma exposure provides for a targeted approach to managing injury risk specific to age division. Objective measures of brain trauma exposure identified in the current study are important to inform strategy, guide legislation and initiate policy for safe play in minor ice hockey.
The effects of an activation-dependent increase in titin stiffness on whole muscle properties using finite element modeling.
Venue: Journal of biomechanics

Active state titin's effects have been studied predominantly in sarcomere or muscle fiber segment level and an understanding of its functional effects in the context of a whole muscle, and the mechanism of those is lacking. By representing experimentally observed calcium induced stiffening and actin-titin interaction induced reduced free spring length effects of active state titin in our linked fiber-matrix mesh finite element model, our aim was to study the mechanism of effects and particularly to determine the functionally more effective active state titin model. Isolated EDL muscle of the rat was modeled and three cases were studied: passive state titin (no change in titin constitutive equation in the active state), active state titin-I (constitutive equation involves a higher stiffness in the active state) and active state titin-II (constitutive equation also involves a strain shift coefficient accounting for titin's reduced free spring length). Isometric muscle lengthening was imposed (initial to long length, lm = 28.7 mm to 32.7 mm). Compared to passive state titin, (i) active state titin-I and II elevates muscle total (lm = 32.7 mm: 14% and 29%, respectively) and active (lm = 32.7 mm: 37.5% and 77.4%, respectively) forces, (ii) active state titin-II also shifts muscle's optimum length to a longer length (lm = 29.6 mm), (iii) active state titin-I and II limits sarcomere shortening (lm = 32.7 mm: up to 10% and 20%, respectively). Such shorter sarcomere effect characterizes active state titin's mechanism of effects. These effects become more pronounced and functionally more effective if not only calcium induced stiffening but also a reduced free spring length of titin is accounted for.
Differences in movement limitations in different low back pain severity in functional tests using an RGB-D camera.
Venue: Journal of biomechanics

Low back pain (LBP) can lead to motor control disturbance which can be one of the causes of reoccurrence of the complaint. It is important to improve our knowledge of movement related disturbances during assessment in LBP and to classify patients according to the severity. The aim of this study is to present differences in kinematic variables using a RGB-D camera in order to classify LBP patients with different severity. A cross-sectional study was carried out. Subjects with non-specific subacute and chronic LBP were screened 6 weeks following an episode. Functional tests were bending trunk test, sock test and sit to stand test. Participants performed as many repetitions as possible during 30 s for each functional test. Angular displacement, velocity and acceleration, linear acceleration, time and repetitions were analysed. Participants were divided into two groups to determine their different LBP severity with a k-means clusters according to the results obtained in Roland Morris questionnaire (RMQ). Comparing different severity groups based on RMQ score (high impact = 17.15, low impact = 7.47), bending trunk test obtained significative differences in linear acceleration (p = 0.002-0.01). The differences of total linear acceleration during the Sit to Stand test were significative (p = 0.004-0.02). Sock test showed not significative differences between groups (p > 0.05). Linear acceleration variables during Sit to Stand test and Bending trunk test were significatively different between the different severity groups. RGB-D camera system and functional tests can detect kinematic differences in different type of LBP according to the functionality.
Towards the simulation of active cardiac mechanics using a smoothed finite element method.
Venue: Journal of biomechanics

In the last decades, various computational models have been developed to simulate cardiac electromechanics. The most common numerical tool is the finite element method (FEM). However, this method crucially depends on the mesh quality. For complex geometries such as cardiac structures, it is convenient to use tetrahedral discretisations which can be generated automatically. On the other hand, such automatic meshing with tetrahedrons together with large deformations often lead to elements distortion and volumetric locking. To overcome these difficulties, different smoothed finite element methods (S-FEMs) have been proposed in the recent years. They are known to be volumetric locking free, less sensitive to mesh distortion and so far have been used e.g. in simulation of passive cardiac mechanics. In this work, we extend for the first time node-based S-FEM (NS-FEM) towards active cardiac mechanics. Firstly, the sensitivity to mesh distortion is tested and compared to that of FEM. Secondly, an active contraction in circumferentially aligned fibre direction is modelled in the healthy and the infarcted case. We show, that the proposed method is more robust with respect to mesh distortion and computationally more efficient than standard FEM. Being furthermore free of volumetric locking problems makes S-FEM a promising alternative in modelling of active cardiac mechanics, respectively electromechanics.
Knee-specific gait biomechanics are reliable when collected in multiple laboratories by independent raters.
Venue: Journal of biomechanics

Multi-centre gait biomechanics studies provide the opportunity to increase sample size and the confidence in results, yet differences between centres may introduce additional error. While previous investigations have compared gait biomechanics from different laboratories assessed by different raters, estimates of relative reliability, measurement error, and thresholds for real change are still unknown. These metrics are imperative to interpret multi-centre study results. Therefore, we examined the reliability of gait biomechanics assessed in two different laboratories, by two different raters, and using the same study sample. Twelve healthy participants underwent gait assessments by two raters in two laboratories at different institutions. Identical protocols were used to collect five walking trials per participant. Discrete data were examined for knee joint angles and moments, gait speed, and stride length. Reliability was assessed using the intraclass correlation coefficient (ICC), standardized error of the measurement (SEM), minimum detectable difference (MDD), and Bland and Altman plots. All spatiotemporal, joint angle, and joint moment measures had ICCs = 0.83-0.94, except for the knee adduction moment peak in late stance (ICC = 0.69 and 0.72). The knee adduction moment SEMs indicate that measurement errors due to the laboratory effect are between 0.19% and 0.31% body weight times height (0.03-0.05 Nm/kg). Meanwhile, measurement error for the knee flexion-extension angle is <2°. Our results are similar to previous test-retest reliability results from a single laboratory, and multiple laboratories, while adding previously unreported reliability metrics necessary for interpreting multi-centre study results.
Unilateral above-knee amputees achieve symmetric mediolateral ground reaction impulse in walking using an asymmetric gait strategy.
Venue: Journal of biomechanics

The ability to sustain steady straight-ahead walking is one goal of gait rehabilitation for individuals with unilateral above-knee (UAK) amputation. Despite the morphological and musculoskeletal asymmetry resulting from unilateral limb loss, the mediolateral ground-reaction-impulse (GRI) should be counterbalanced between the affected and unaffected limbs during straight-ahead walking. Therefore, we investigated the strategies of mediolateral ground-reaction-force (GRF) generation adopted by UAK prosthesis users walking along a straight path. GRFs of 15 participants with UAK amputation were measured during straight-ahead walking. Then, the mediolateral GRI, stance time, and mean mediolateral GRF during the stance phase of the affected and unaffected limbs were compared. To better understand the GRF generation strategy, statistical-parametric-mapping (SPM) was applied to assess the phase-dependent difference of the mediolateral GRFs between two limbs. The results showed that UAK prosthesis users can achieve symmetric mediolateral GRI during straight-ahead walking by adopting an asymmetric gait strategy: shorter stance time and higher mean mediolateral GRF over the stance phase for the affected than for the unaffected limb. In addition, the analysis using SPM revealed that the affected limb generates a higher mean medial GRF component than the unaffected limb, especially during the single-support phase. Thus, a higher medial GRF during the single-support phase of the affected limb may allow UAK prosthesis users to achieve mediolateral GRI that are similar to those of the unaffected limb. Further insights on these mechanics may serve as guidelines on the improved design of prosthetic devices and the rehabilitation needs of UAK prosthesis users.
Running in circles: Describing running kinematics using Fourier series.
Venue: Journal of biomechanics

We explore the use of Fourier series to describe the kinematics of human running. From a database of 285 trials of treadmill running, we drive a musculoskeletal model with 104 anatomical joint angles to obtain kinematics. Using FFT analysis, we determine a fundamental frequency for all independent joint angles and compute average step kinematics. Finally, we represent the average step kinematics using Fourier series with numbers of coefficient pairs ranging from one through ten. We find that five or fewer Fourier coefficient pairs provide an accurate (Pearson's correlation > 0.99 and root mean square difference < 0.5 degrees) representation for most joint angles. In conclusion, Fourier series appear to provide a compact and valid representation of running kinematics, thus enabling researchers to confidently use Fourier series in research of human running.
Test-retest reliability of force plate-derived measures of reactive stepping.
Venue: Journal of biomechanics

Characterizing reactive stepping is important to describe the response's effectiveness. Timing of reactive step initiation, execution, and termination have been frequently reported to characterize reactive balance control. However, the test-retest reliabilities of these measures are unknown. Accordingly, the purpose of this study was to determine the between- and within-session test-retest reliabilities of various force plate-derived measures of reactive stepping. Nineteen young, healthy adults responded to 6 small (~8-10% of body weight) and 6 large perturbations (~13-15% of body weight) using an anterior lean-and-release system. Tests were conducted during two visits separated by at least two days. Participants were instructed to recover balance in as few steps as possible. Step onset, foot-off, swing, and restabilization times were extracted from force plates. Relative test-retest reliability was determined through intraclass correlation coefficients (ICCs) and 95% confidence intervals (CIs). Absolute test-retest reliability was assessed using the standard error of the measurement (SEM). Foot-off and swing times had the highest between- and within-session test-retest reliabilities regardless of perturbation size (between-session ICC = 0.898-0.942; within-session ICC = 0.455-0.753). Conversely, step onset and restabilization times had lower ICCs and wider CIs (between-session ICC = 0.495-0.825; within-session ICC = -0.040-0.174). Between-session test-retest reliability was higher (ICC = 0.495-0.942) for all measures than within-session test-retest reliability (ICC = -0.040-0.753). Time to restabilization had the highest SEM, indicating the worst absolute reliability of the measures. These findings suggest multiple baseline sessions are needed for measuring restabilization and step onset times. The minimal detectable changes reported provide an index for measuring meaningful change due to an intervention.
Shank and rearfoot coordination and its variability during running in flatfoot.
Venue: Journal of biomechanics

Flatfoot is a risk factor for patellofemoral pain syndrome (PFPS), and excessive rearfoot eversion occurring in flatfoot has been associated with the development and progression of PFPS; however, the mechanism remains unclear. This study aimed to investigate transverse shank and frontal rearfoot coordination patterns and variability when running with normal foot and flatfoot. Participants with normal foot (n = 13) and flatfoot (n = 13) were asked to run at their preferred speed. The coupling angle between the shank and rearfoot, representing intersegmental coordination, was calculated using the modified vector coding technique and categorized into four coordination patterns. Standard deviation of the coupling angle was computed as a measure of coordination variability during the stance phase. No differences in the characteristics and spatiotemporal parameters between groups were found, and all participants had rearfoot strike pattern. During midstance, the flatfoot group showed a significantly greater proportion of anti-phase with proximal (shank) dominancy than the normal foot group (p = 0.04, effect size = 0.88 [large]). Furthermore, flatfoot group showed a significantly greater in variability than the normal foot group (p = 0.03, effect size = 0.91 [large]). This study's results may help explain why flatfoot is likely to result in PFPS. However, the occurrence mechanism of running injuries like PFPS is multi- factorial. Since these results alone are not sufficient to explain the cause-effect relationship between flatfoot and injuries like PFPS, a prospective study including other factors such as patellofemoral joint stress would also be needed.
Biomechanical and viscoelastic properties of the ankle muscles in men with previous history of ankle sprain.
Venue: Journal of biomechanics

In this study, we aimed to explore the impact of previous history of lateral ankle sprain on the mechanical and viscoelastic properties of the tibialis anterior (TA), peroneus longus (PL) and gastrocnemius lateralis (GL) and medialis (GM) in asymptomatic men. For this purpose, a group of 26 men with previous history of lateral ankle sprain (ASG) and a control group (CG) of 29 healthy counter-parts participated in this study. Tone, stiffness, elasticity and mechanical stress relaxation time were measured using a myotonometer in a single session. Higher tone was noted for TA and GL in ASG as compared to CG (effect size of Cohen's d = 0.57 [p = 0.04] and 0.59 [p = 0.04], respectively). Further, stiffness was higher in ASG than in CG for TA (d = 0.56; p = 0.04), PL (d = 0.58; p = 0.04) and GL (d = 0.63; p = 0.02). Stress relaxation time was also lower for the ASG compared to the CG for TA (d = 0.61; p = 0.03), PL (d = 0.55; p = 0.04) and GL (d = 0.68; p = 0.02). There were no significant differences between groups in elasticity (p > 0.05). GM experienced no significant changes after ankle sprain in any of the variables (p > 0.05). To conclude, previous history of lateral ankle sprain results in higher TA and GL muscle tone. Likewise, these muscles in addition to PL exhibit less deformation against resistance due to their increased stiffness, thus needing a shorter time to restore to their original shape after deformation.
Biphasic plating improves the mechanical performance of locked plating for distal femur fractures.
Venue: Journal of biomechanics

Internal fixation by plate osteosynthesis is the gold standard treatment for distal femur fractures. Despite improvements that preserve the biological conditions for bone healing, there are concerns standard locked plating constructs may be overly stiff. Biphasic plating is a novel concept designed to provide suitable fracture motion and increased implant strength to support early full weight-bearing. This study aims to demonstrate that the Biphasic Plate can be incorporated into a pre-contoured distal femur plate while providing adequate flexibility and increased implant strength. The mechanical performance of the Biphasic Plate (BP) was investigated in comparison to a standard locking plate for the distal femur (LCP-DF). Constructs were formed by mounting the implants on a bone substitute. The construct stiffness and strength under axial loading and the magnitude of interfragmentary movement were determined using finite element analysis. The Biphasic Plate exhibited a bi-linear stiffness response; at low loads, the BP construct was 55% more compliant and at high loads 476% stiffer than the LCP-DF. The Biphasic Plate provided more consistent interfragmentary movement over a wider loading range. At partial weight-bearing loads, the Biphasic Plate produced larger interfragmentary movements (0.18 vs. 0.04 mm). However, at loads equivalent to full weight-bearing, the maximum movements were substantially smaller than the LCP-DF construct (1.5 vs. 3.5 mm). The increased flexibility at low loads was provided without sacrificing implant strength with peak stress in the Biphasic Plate 63% lower than the LCP-DF construct. The biphasic plating concept can be successfully incorporated into anatomically contoured distal femur plates while providing adequate flexibility and increasing implant strength.
Tissue engineered platforms for studying primary and metastatic neoplasm behavior in bone.
Venue: Journal of biomechanics

Cancer is the second leading cause of death in the United States, claiming more than 560,000 lives each year. Osteosarcoma (OS) is the most common primary malignant tumor of bone in children and young adults, while bone is a common site of metastasis for tumors initiating from other tissues. The heterogeneity, continual evolution, and complexity of this disease at different stages of tumor progression drives a critical need for physiologically relevant models that capture the dynamic cancer microenvironment and advance chemotherapy techniques. Monolayer cultures have been favored for cell-based research for decades due to their simplicity and scalability. However, the nature of these models makes it impossible to fully describe the biomechanical and biochemical cues present in 3-dimensional (3D) microenvironments, such as ECM stiffness, degradability, surface topography, and adhesivity. Biomaterials have emerged as valuable tools to model the behavior of various cancers by creating highly tunable 3D systems for studying neoplasm behavior, screening chemotherapeutic drugs, and developing novel treatment delivery techniques. This review highlights the recent application of biomaterials toward the development of tumor models, details methods for their tunability, and discusses the clinical and therapeutic applications of these systems.