nils-herrmann/clean_scirepeval huggingface dataset:
Automatic segment filtering procedure for processing non-stationary signals.
Venue: Journal of biomechanics

Computing time derivatives is a frequent stage in the processing of biomechanical data. Unfortunately, differentiation amplifies the high frequency noise inherent within the signal hampering the accuracy of signal derivatives. A low-pass Butterworth filter is commonly used to reduce the sampled signal noise prior to differentiation. One hurdle lies in selecting an appropriate filter cut-off frequency which retains the signal of interest while reducing deleterious noise. Most biomechanics data processing approaches utilize the same cut-off frequency for the whole sampled signal, but the frequency components of a signal can vary with time. To accommodate such signals, the Automatic Segment Filtering Procedure (ASFP) is proposed which uses different automatically determined Butterworth filter cut-off frequencies for separate segments of a sampled signal. The Teager-Kaiser Energy Operator of the signal is computed and used to determine segments of the signal with different energy content. The Autocorrelation-Based Procedure (ABP) is used on each of these segments to determine filter cut-off frequencies. This new procedure was evaluated by estimating acceleration values from the test data set of Dowling (1985). The ASFP produced a root mean square error (RMSE) of 16.4 rad s-2 (26.6%) whereas a single ABP determined filter cut-off frequency applied to the whole Dowling (1985) signal, representing the common approach, produced a RMSE of 25.5 rad s-2 (41.4%). As a point of comparison, a Generalized Cross-Validated Quintic Spline, a common non-Butterworth filter, produced a RMSE of 23.6 rad s-2 (38.4%). This new automatic approach is advantageous in biomechanics for preserving high frequency content of non-stationary signals.
Subject-specific regression equations to estimate lower spinal loads during symmetric and asymmetric static lifting.
Venue: Journal of biomechanics

Workplace safety assessment, personalized treatment design and back pain prevention programs require accurate subject-specific estimation of spinal loads. Since no noninvasive method can directly estimate spinal loads, easy-to-use regression equations that are constructed based on the results of complex musculoskeletal models appear as viable alternatives. Thus, we aim to develop subject-specific regression equations of L4-L5 and L5-S1 shear and compression forces during various symmetric/asymmetric tasks using a nonlinear personalized finite element musculoskeletal trunk model. Kinematics and electromyography (EMG) activities of 19 young healthy subjects were collected during 64 different symmetric/asymmetric tasks. To investigate the reliability and accuracy of the musculoskeletal model and regression equations, we compared estimated trunk muscle activities and L4-L5 intradiscal pressures (IDPs) respectively with our own electromyography data (EMGs) and reported in vivo pressure measurements. Although in general, six independent rotation components (three trunk T11 rotations and three pelvic S1 rotations) are required to determine kinematics along the spine, only two surrogate variables (trunk flexion and its asymmetric angles) satisfactorily predicted all six rotation components (R2 > 0.94). Regression equations, developed based on subject-specific inputs, predicted spinal loads in satisfactory agreement with IDP measurements (R2 = 0.85). Predicted muscle activities in the personalized musculoskeletal models were in moderate to weak agreements with our measured EMGs in 19 participants. Based on dominance analysis, trunk flexion and its asymmetry angle, hand-load weight, hand-load lever arm, and body weight were the most important variables while the effects of body height and sex on spinal loads remained small.
Intravaginal pressure profile of continent and incontinent women.
Venue: Journal of biomechanics

A well-functioning pelvic floor muscle plays an important role in maintaining urinary continence. The aim of this study was to describe and compare the intravaginal pressure profile using a multisensor device along the vaginal length in women with and without urinary incontinence (UI), while performing pelvic floor muscle tasks. Fifty-four adult pre-menopausal women (31 continent and 23 incontinent) participated in this cross-sectional observational cohort study. The intravaginal pressure profile was assessed at rest, during maximum and sustained pelvic floor muscle contractions, using the Pliance® multisensor device. Between-group comparisons were performed considering the overall pressure and the pressure profile of 10-subregions along the vaginal length. In the overall pressure assessment, women with UI presented lower pressures at rest, similar pressures during maximum contraction and lower capacity to maintain pressure during sustained contraction compared to those in the continent group. The pressure profile assessment showed between-group differences that were consistent throughout tasks, with the incontinent group presenting lower pressures than the continent group, specifically in the mid-vaginal length, around 3-4 cm from the vaginal opening. We observed consistent deficits in pressure generation in incontinent compared to continent women, precisely in the region of the pelvic floor muscles. With this protocol and novel instrument, we obtained a reliable and consistent intravaginal pressure profile of continent and incontinent women. This approach could assist clinicians in the assessment of pelvic floor muscle function and foster a better understanding of the urinary incontinence mechanism.
Alteration of movement patterns in low back pain assessed by Statistical Parametric Mapping
Venue: Journal of biomechanics

Changes in movement pattern in low back pain (LBP) groups have been analysed by reporting predefined discrete variables. However, this approach does not consider the full kinematic data waveform and its dynamic information, potentially exposing the analysis to bias. Statistical Parametric Mapping (SPM) has been introduced and applied to 1 dimensional (D) kinematic variables allowing the assessment of data over time. The aims of this study were to assess differences in 3D kinematics patterns in people with and without LBP during functional tasks by using SPM and to investigate if SPM analysis was consistent with standard 3D range of motion (RoM) assessments. 3D joints kinematics of the spine and lower limbs were compared between 20 healthy controls and 20 participants with non-specific LBP during walking, sit-to-stand and lifting. SPM analysis showed significant differences in the 3Dkinematics of the lower thoracic segment, upper and lower lumbar segment and knee joint during walking and lifting mostly observed at the beginning and/or towards the end of the tasks. ROMs differed between groups in the lower thoracic segment (walking/sit-to-stand), upper and lower lumbar segments (walking/sit-to-stand/lifting), hip and knee (sit-to-stand/lifting). Based on these results, the two approaches can yield different data interpretations. SPM analysis allows the identification of differences in movement that occur over time. This adds value to LBP movement analysis as it allows an understanding of the LBP strategies adopted during motion that may not be conveyed by simple discrete parameters such as ROMs.
Quantifying deformations and strains in human intervertebral discs using Digital Volume Correlation combined with MRI (DVC-MRI).
Venue: Journal of biomechanics

Physical disruptions to intervertebral discs (IVDs) can cause mechanical changes that lead to degeneration and to low back pain which affects 75% of us in our lifetimes. Quantifying the effects of these changes on internal IVD strains may lead to better preventative strategies and treatments. Digital Volume Correlation (DVC) is a non-invasive technique that divides volumetric images into subsets, and measures strains by tracking the internal patterns within them under load. Applying DVC to MRIs may allow non-invasive strain measurements. However, DVC-MRI for strain measurements in IVDs has not been used previously. The purpose of this study was to quantify the strain and deformation errors associated with DVC-MRI for measurements in human IVDs. Eight human lumbar IVDs were MRI scanned (9.4 T) for a 'zero-strain study' (multiple unloaded scans to quantify noise within the system), and a loaded study (2 mm axial compression). Three DVC methodologies: Fast-Fourier transform (FFT), direct correlation (DC), and a combination of both FFT and DC approaches were compared with subset sizes ranging from 8 to 88 voxels to establish the optimal DVC methodology and settings which were then used in the loaded study. FFT + DC was the optimal method and a subset size of 56 voxels (2520 µm) was found to be a good compromise between errors and spatial resolution. Displacement and strain errors did not exceed 28 µm and 3000 microstrain, respectively. These findings demonstrate that DVC-MRI can quantify internal strains within IVDs non-invasively and accurately. The method has unique potential for assessing IVD strains within patients.
Evaluation of human nasal cartilage nonlinear and rate dependent mechanical properties.
Venue: Journal of biomechanics

Nasal reconstruction frequently requires donor cartilage and tissue, and ideally, donor tissue will closely emulate native nasal cartilage mechanics. Tissue engineering scaffolds, especially 3D printed scaffolds, have been proposed for nasal reconstruction, and the success of these constructs may depend on how well scaffolds reflect native nasal cartilage mechanical properties. Therefore, consistent and comprehensive characterization of native nasal cartilage mechanical properties is a foundation for nasal cartilage tissue engineering and reconstruction in general by providing design targets for reconstructive materials. Our group has previously shown the feasibility of producing scaffolds with porous architecture permitting chondrocyte growth and cartilage production. In this study, we determined the nonlinear and stress relaxation behavior of human nasal cartilage under unconfined compression. We then fit this experimental data to nonlinear elastic, nonlinear viscoelastic and nonlinear biphasic constitutive models. The resulting coefficients will provide design targets for nasal reconstruction and scaffold design as well as outcome measures for assessment of tissue engineered nasal cartilage.
Total disc arthroplasties alter the characteristics of the instantaneous helical axis of the cervical functional spinal units C3/C4 and C5/C6 during flexion and extension in in vitro conditions.
Venue: Journal of biomechanics

Total disc arthroplasty (TDA) increases the risk of adjacent segment disease (ASD). Kinematic analyses are necessary to compare the intact condition (IC) with alterations after TDA to develop better prostheses. A well-established 6D measuring apparatus (resolution < 2.4 μm; 400 positions/cycle) was used. Kinematics of the flexion and extension of 8 human cervical spine segments (cFSU) C3/C4 and C5/C6 (67.9 ± 13.2 y) were analyzed in the IC and after TDA (Bryan® Cervical Disc [B-TDA], Prestige LP® Cervical Disc [P-TDA]). The migration of the instantaneous helical axis (IHA) and the stiffness of the segments were calculated. Analyses demonstrated a stretched U-curved IHA migration in the sagittal plane. The IHA positions were significantly more cranial in cFSU C5/C6 than in C3/C4 in IC and after either TDA (IC: p < 0.001; B-TDA: p = 0.001; P-TDA: p = 0.045). In cFSU C3/C4 IHA positions shifted anteriocranially after either TDA (p < 0.001). In cFSU C5/C6, the IHA positions were significantly more anterocranial after B-TDA than in IC and after P-TDA (anterior: p < 0.001; cranial: p = 0.005). After B-TDA, the IHA migration path length was significantly longer in cFSU C3/C4 than in C5/C6 (p = 0.007) and longer than in IC in both cFSU (C3/C4: p = 0.047; C5/C6: p < 0.001). Stiffness was increased after both TDA. Various kinematic alterations were observed after both TDA. Increased translation and IHA position shifting after both TDA might indicate abnormal strain and a derogated benefit of TDA. These results imply the most abnormal strain after B-TDA. The lower cFSU might be more susceptible to alterations after TDA than the upper cFSU.
Effects of in vivo fatigue-induced subchondral bone microdamage on the mechanical response of cartilage-bone under a single impact compression.
Venue: Journal of biomechanics

Subchondral bone (SCB) microdamage is prevalent in the joints of human athletes and animals subjected to high rate and magnitude cyclic loading of the articular surface. Quantifying the effect of such focal in vivo fatigue-induced microdamage on the mechanical response of the tissue is critical for the understanding of joint surface injury and the development of osteoarthritis. Thus, we aimed to quantify the mechanical properties of cartilage-bone from equine third metacarpal (MC3) condyles, which is a common area of accumulated microdamage due to repetitive impact loading. We chose a non-destructive technique, i.e. high-resolution microcomputed tomography (µCT) imaging, to identify various degrees of in vivo microdamage in SCB prior to mechanical testing; because µCT imaging can only identify a proportion of accumulated microdamage, we aimed to identify racing and training history variables that provide additional information on the prior loading history of the samples. We then performed unconfined high-rate compression of approximately 2% strain at 45%/s strain rate to simulate a cycle of gallop and used real-time strain measurements using digital image correlation (DIC) techniques to find the stiffness and shock absorbing ability (relative energy loss) of the cartilage-bone unit, and those associated with cartilage and SCB. Results indicated that stiffness of cartilage-bone and those associated with the SCB decreased with increasing grade of damage. Whole specimen stiffness also increased, and relative energy loss decreased with higher TMD, whereas bone volume fraction of the SCB was only associated negatively with the stiffness of the bone. Overall, the degree of subchondral bone damage observed with µCT was the main predictor of stiffness and relative energy loss of the articular surface of the third metacarpal bone of Thoroughbred racehorses under impact loading.
Measuring markers of aging and knee osteoarthritis gait using inertial measurement units.
Venue: Journal of biomechanics

Differences in gait with age or knee osteoarthritis have been demonstrated in laboratory studies using optical motion capture (MoCap). While MoCap is accurate and reliable, it is impractical for assessment outside the laboratory. Inertial measurement units (IMUs) may be useful in these situations. Before IMUs are used as a surrogate for MoCap, methods that are reliable, repeatable, and that calculate metrics at similar accuracy to MoCap must be demonstrated. The purpose of this study was to compare spatiotemporal gait parameters and knee range of motion calculated via MoCap to IMU-derived variables and to compare the ability of these tools to discriminate between groups. MoCap and IMU data were collected from young, older, and adults with knee osteoarthritis during overground walking at three self-selected speeds. Walking velocity, stride length, cadence, percent of gait cycle in stance, and sagittal knee range of motion were calculated and compared between tools (MoCap and IMU), between participant groups, and across speed. There were no significant differences between MoCap and IMU outcomes, and root mean square error between tools was ≤0.05 m/s for walking velocity, ≤0.07 m for stride length, ≤0.5 strides/min for cadence, ≤5% for percent of gait cycle in stance, and ≤1.5° for knee range of motion. No interactions were present, suggesting that MoCap and IMU calculated metrics similarly across groups and speeds. These results demonstrate IMUs can accurately calculate spatiotemporal variables and knee range of motion during gait in young and older, asymptomatic and knee osteoarthritis cohorts.
Muco-ciliary clearance: A review of modelling techniques.
Venue: Journal of biomechanics

The airways of the human respiratory system are covered by a protective layer, which is known as airway surface liquid (ASL). This layer consists of two relatively distinct sub-layers; a mucus layer (ML), and a periciliary liquid layer (PCL). In addition, the airways are lined with a dense mat of hair-like structures, called cilia, which beat back and forth in a co-ordinated manner and mainly propel the mucus layer. Such interaction between the cilia and mucus is called 'muco-ciliary clearance' (MCC) which is essential to clear the respiratory airways from the inhaled toxic particles deposited on the mucus. The complex nature of lung clearance mechanisms limit the ability to conduct experiments to investigate micro-scale physiological phenomena. As such, modelling techniques are commonly implemented to investigate the effects of biological parameters on the lung muco-ciliary clearance. In the present work, modelling techniques of cilia-ASL interactions - including continuum cilia modelling and discrete cilia modelling - are reviewed and the numerical procedures and level of complexity related to each technique are explained. This is followed by a detailed analysis of the airway surface liquid modelling approaches. In addition, findings of numerical investigations related to the effects of various parameters such as ciliary beat frequency (CBF), mucus rheology, metachronal waves of cilia, surface tension at the PCL-mucus interface, ciliary length, ciliary density, and airway surface liquid depth on the bronchial and tracheal ASL transport are reviewed. This review also explains how these biological parameters can alter the internal power required to perform ciliary beating. Lastly, the main limitations of current numerical works are discussed and significant research directions are brought forward that may be considered in future models to better understand this complex human biological system and its vital clearance mechanism.
Glenohumeral stabilizing roles of the scapulohumeral muscles: Implications of muscle geometry.
Venue: Journal of biomechanics

Dynamic stability provided by muscles is integral for function and integrity of the glenohumeral joint. Although the high degree of inter-individual variation that exists in musculoskeletal geometry is associated with shoulder injuries, there is limited research associating the effects of muscle geometry on the potential stabilizing capacities of shoulder muscles. The purpose of this investigation was to evaluate the stabilizing functions of the scapulohumeral muscles using computational modeling and to quantify the sensitivity of muscle stabilizing roles to changes in muscle geometry. Muscle stability ratios in the superior/inferior and anterior/posterior directions were computed as the ratio between the muscle's shear components relative to compression throughout arm elevation in the scapular plane. Muscle attachment locations on the clavicle, scapula, and humerus were iteratively adjusted using Monte Carlo simulations. Consistent with previous experimental studies, the rotator cuff muscles were identified as the primary stabilizers of the glenohumeral joint; whereas the deltoids and coracobrachialis have a strong potential for superiorly translating the humerus at low elevation angles. Variations in the stability ratios due to altered muscle geometry were muscle- and angle-specific. In general, the highest variation was observed for the subscapularis and deltoids (at low elevation angles), while the remaining rotator cuff muscles largely maintained their capacity to provide compressive stabilizing forces at the glenohumeral joint. Changes in muscle stability ratios may affect dynamic stability of the humerus that could differentially predispose individuals to greater risk for injury.
The impact of obesity on gait stability in older adults.
Venue: Journal of biomechanics

Obesity increases fall risk, and fall-related injuries in older adults. While prior work suggests obesity influences postural stability during standing, little is known about how obesity affects walking stability. Therefore, this study compared walking stability in older adults with and without obesity. Exploratory analyses were also conducted to evaluate the associations between measures of body habitus and gait stability as well as the association between prospective stumbles and falls and gait stability. A total of 34 older adults (17 with obesity, 17 with normal weight) walked on a treadmill at a self-selected speed. Walking stability was quantified as the local dynamic stability of the trunk in all three planes of motion. Participants also performed a series of functional tests, and were followed for a one-year period during which they reported falls and stumbles. Although participants with obesity performed significantly worse than participants without obesity on most functional tests, there were no differences in stability between groups in any direction (p = 0.18-0.78; η2 = 0.003-0.056), nor between those with and without a prospective fall or stumble (p = 0.18-0.93; η2 = 0.003-0.054). There were significant, albeit weak, correlations between BMI, waist circumference, and waist-to-height ratio and walking instability (p = 0.027-0.042; ρ = 0.36-0.39). Increased body mass, in absence of other obesity-related comorbidities, may have minimum impact on walking stability and in turn fall risk in older adults.
Computational hemodynamics in arteries with the one-dimensional augmented fluid-structure interaction system: viscoelastic parameters estimation and comparison with in-vivo data.
Venue: Journal of biomechanics

Mathematical models are widely recognized as a valuable tool for cardiovascular diagnosis and the study of circulatory diseases, especially to obtain data that require otherwise invasive measurements. To correctly simulate body hemodynamics, the viscoelastic properties of vessels walls are a key aspect to be taken into account as they play an essential role in cardiovascular behavior. The present work aims to apply the augmented fluid-structure interaction system of blood flow to real case studies to assess the validity of the model as a valuable resource to improve cardiovascular diagnostics and the treatment of pathologies. Main contributions of the paper include the evaluation of viscoelastic tube laws, estimation of viscoelastic parameters and comparison of models with literature results and in-vivo experiments. The ability of the model to correctly simulate pulse waveforms in single arterial segments is verified using literature benchmark test cases, designed taking into account a simple elastic behavior of the wall in the upper thoracic aorta and in the common carotid artery. Furthermore, in-vivo pressure waveforms, extracted from tonometric measurements performed on four human common carotid arteries and two common femoral arteries, are compared to numerical solutions. It is highlighted that the viscoelastic damping effect of arterial walls is required to avoid an overestimation of pressure peaks. Finally, an effective procedure to estimate the viscoelastic parameters of the model is herein proposed, which returns hysteresis curves of the common carotid arteries dissipating energy fractions in line with values calculated from literature hysteresis loops in the same vessel.