nils-herrmann/clean_scirepeval huggingface dataset:
Increased core stability is associated with reduced knee valgus during single-leg landing tasks: Investigating lumbar spine and hip joint rotational stiffness.
Venue: Journal of biomechanics

Knee valgus during landing has been identified as a strong correlate of ACL injury. Inappropriate trunk control during landing contributes to high knee valgus, with neuromuscular factors related to core stability postulated as the mechanism. This investigation probed the influence of trunk and hip mechanics, including joint stiffness, on knee mechanics, particularly high knee valgus. Specifically, this study quantified lumbar spine and hip joint rotational stiffness (a proxy for mechanical joint stability) during single-leg landing tasks known to be associated with injury risk, particularly in females. Kinematics, kinetics, and 24 channels of electromyography spanning the trunk and hip musculature were measured in 18 healthy female participants. Anatomically detailed EMG-driven musculoskeletal models quantified lumbar spine and hip joint rotational stiffness. The links between peak knee abduction angle and moment with lumbar spine and hip joint rotational stiffness were measured. Hip joint rotational stiffness influenced knee abduction across tasks (correlation coefficient ranging from -0.48 to -0.70, p < 0.05) to reduce valgus deviation. Similarly, transverse plane hip joint rotational stiffness during landings reduced knee abduction moment (R = -0.50, P = 0.03; R = -0.49, P = 0.04), and lumbar spine joint rotational stiffness reduced knee abduction angle and moment but did not consistently reach statistical significance. The control system uses stiffness to control motion. This study demonstrates the importance of proximal (lumbar spine and hip) joint rotational stiffness (i.e. core control stability) during single-leg landing to prevent knee abduction motion. Instantaneous core stability is achieved with the coordinated activation and stiffness of both trunk and hip muscles.
The gait is less stable in children with cerebral palsy in normal and dual-task gait compared to typically developed peers.
Venue: Journal of biomechanics

There is limited evidence about gait stability and its alteration by concurrent motor and cognitive tasks in children with cerebral palsy (CP). We examined gait stability and how it is altered by constrained cognitive or motor task in CP and their typically developed (TD) controls. Gait kinematics were recorded using inertial-measurement units (IMU) from 18 patients with hemiplegia (13.5 ± 2.4 years), 12 with diplegia (13.0 ± 2.1 years), and 31 TD controls (13.5 ± 2.2 years) during unconstrained gait, and motor (carrying a tray) and cognitive (word naming) task constrained gait at preferred speed (~400 steps/task). Step duration, its standard deviation and refined-compound-multiscale entropy (RCME) were computed independently for vertical and resultant horizontal accelerations. Gait complexity was higher for patients with CP than TD in all tasks and directions (p < 0.001-0.01), being pronounced in vertical direction, cognitive task and for diplegic patients (p < 0.05-0.001). The gait complexity increased more (i.e. higher dual-task cost) from the unconstrained to the constrained gait in CP compared to TD (p < 0.05). Step duration was similar in all groups (p > 0.586), but its variation was higher in CP than TD (p < 0.001-0.05), and during the constrained than unconstrained gait in all groups (p < 0.01-0.001). The gait in children with CP was more complex and the dual-task cost was higher primarily for children with diplegic CP than TD during cognitive task, indicating that attentional load hinders their gait more. This raises the hypothesis that more attention and cortical resources are needed to compensate for the impaired gait in children with CP.
Numerical-experimental analysis of the permeability-porosity relationship in triply periodic minimal surfaces scaffolds.
Venue: Journal of biomechanics

Bone Tissue Engineering has been focusing on improving the current methods for bone repair, being the use of scaffolds presented as an upgrade to traditional surgery techniques. Scaffolds are artificially porous matrices, meant to promote cell seeding and proliferation, being these properties influenced by the permeability of the structure. This work employed experimental pressure drop tests and Computational Fluid Dynamics models to assess permeability (and fluid streamlines) within different triply periodic minimal surfaces scaffold geometries (Schwarz D, Gyroid and Schwarz P). The pressure outputs from the computational analysis presented a good correlation with the experimental results, with R2 equal to 0.903; they have also shown that a lower porosity may not mean a lower permeability if the geometry is altered, such as the difference between 60% porous Gyroid scaffolds (8.1*10-9 mm2) and 70% porous Schwarz D scaffolds (7.1*10-9 mm2). Fluid streamlines revealed how the Gyroid geometries are the most appropriate design for most bone tissue engineering applications, due to their consistent fluid permeation, followed by Schwarz D. The Schwarz P geometries have shown flat streamlines and significant variation of the permeability with the porosity (an increase of 10% in their porosity lead to an increase in the permeability from 5.1*10-9 mm2 to 11.7*10-9 mm2), which would imply a poor environment for cell seeding and proliferation.
Upper extremity and trunk body segment parameters are affected by BMI and sex.
Venue: Journal of biomechanics

Although body mass index (BMI) relates to body segment parameters (BSPs), unknowns persist over whether: 1) BSPs relate to BMI group classifications, 2) sex influences BMI/BSP relationships, and 3) simple anthropometric measures sufficiently predict BSPs. Dual energy X-ray absorptiometry (DXA) scans and anthropometric measures were obtained from 76 participants (33M, 43F) of varying body composition. Trunk, neck and head (TNH), arm, forearm and hand masses were obtained from DXA scans and center of mass locations (COM) estimated from geometric models. Groups with larger BMIs had lesser hand and forearm mass (%total body mass; p<0.001) and greater TNH mass (p=0.014). Males had greater hand, forearm, and arm masses (p<0.05). TNH COM was inferior in groups with larger BMI (p<0.01) and in males (p=0.006). In females, arm COM was distal in Obese II/III versus Normal (p=0.024). Two sets of linear models were created to predict BSPs; a simplified set with only BMI, height, weight, sex and mass potential predictors and a complex set with additional anthropometric measures. Complex arm and TNH mass models (arm R2=0.43, TNH R2=0.61) explained more variance than simplified models (arm R2=0.1, TNH R2=0.33). Complex hand mass, forearm mass and TNH COM models had smaller R2 increases versus simplified models (hand=0.05, forearm=0.06, TNH=0.08). Explained variance in forearm COM (R2=0.2) and arm COM (R2=0.27) complex models was low, suggesting a constant may provide reasonable estimates. Certain BSPs can be estimated using simplified measures, whereas prediction of other BSPs markedly improves if additional anthropometric measures are included.
Knee flexion angle and muscle activations control the stability of an anterior cruciate ligament deficient joint in gait.
Venue: Journal of biomechanics

Anterior cruciate ligament (ACL) is a primary structure and a commonly injured ligament of the knee joint. Some patients with ACL deficiency (ACLD) experience joint instability and require a reconstructive surgery to return to daily routines, some can adapt by limiting their activities while others, called copers, can return to high-level activities with no instability. We investigated the effects of alterations in the knee flexion angle (KFA) and muscle force activations on the stability and biomechanics of ACLD joints at 25, 50, and 75% periods of gait stance. ACLD joint stability is controlled by variations in both KFA and knee muscle forces. For the latter, a parameter called activity index is defined as the ratio of forces in ACL antagonists (quadriceps and gastrocnemii) to those in ACL agonists (hamstrings). Under a greater KFA (2-6° beyond the mean of reported values in healthy subjects), an ACLD joint regains its pre-injury stability levels. The ACLD joint stability also markedly improves at smaller quadriceps and larger hamstrings forces (activity indices of 2.0-3.6 at 25%) at the first half of stance and smaller gastrocnemii and larger hamstrings forces (activity indices of 0.1-1.1 at 50% and 0.1-1.2 at 75%) at the second half of stance. Activity index and KFA are both crucial when assessing the dynamic stability of an ACLD joint. These results are helpful in our understanding of the biomechanics and stability of ACLD joints towards improved prevention and treatment strategies.
Intrinsic properties of osteomalacia bone evaluated by nanoindentation and FTIRM analysis.
Venue: Journal of biomechanics

Osteomalacia is a pathological bone condition consisting in a deficient primary mineralization of the matrix, leading to an accumulation of osteoid tissue and reduced bone mechanical strength. The amounts, properties and organization of bone constituents at tissue level, are known to influence its mechanical properties. It is then important to investigate the relationship between mechanical behavior and tissue composition at this scale in order to provide a better understanding of bone fragility mechanisms associates with this pathology. Our purpose was to analyze the links between ultra-structural properties and the mechanical behavior of this pathological bone tissue (osteomalacia) at tissue level (mineral and osteoid separately, or global). Four bone biopsies were taken from patients with osteomalacia, and subsequently embedded, sectioned, and polished. Then nanoindentation tests were performed to determine local elastic modulus E, contact hardness Hc and true hardness H for both mineralized and organic bone phases and for the global bone. The creep of the bone was also studied using a special indentation procedure in order to assess visco-elasto-plastic (creep) bone behavior. This allowed a detailed study of the rheological models adapted to the bone and to calculate the parameters associated to a Burgers model. Ultra-structural parameters were measured by Fourier Transform InfraRed Microspectroscopy (FTIRM) on the same position as the indents. The use of rheological models confirmed a significant contribution from the organic phase on the viscous character of bone tissue. The elastic E and the elasto-plastic Hc deformation were correlated to both collagen maturity and Mineral/Matrix. The pure plastic deformation H was only correlated to the mineral phase. Our data show that mineral phase greatly affects mechanical variables (moduli and viscosities) and that organic phase (as illustrated in osteoid tissue) may play an important role in the creep behavior of bone. In conclusion, this study brings mechanical and physicochemical values for osteoid and mineral phases.
The effect of the hip impact configuration on the energy absorption provided by the femoral soft tissue during sideways falls.
Venue: Journal of biomechanics

The femoral soft tissue (i.e., skin, muscle, fat) may play a key role in preventing hip fractures during a fall by absorbing the impact energy. We measured the femoral soft tissue deformation and associated compressive force during simulated sideways falls to estimate the energy absorbed by the soft tissue, and then examined how this was affected by the hip impact configuration and gender. Eighteen young adults (9 males and 9 females) participated in the pelvis release experiment. The pelvis was raised through a rope attached to an electromagnet on the ceiling, so the skin surface barely touches the ultrasound probe, which flush to a Plexiglas plate placed on a force plate. The electromagnet was turned off to cause a fall while the soft tissue deformation and associated compressive force were being recorded. Trials were acquired with three hip impact configurations. An outcome variable included the energy absorbed by the femoral soft tissue during a fall. The energy absorbed by the femoral soft tissue ranged from 0.03 to 3.05 J. Furthermore, the energy absorption was associated with the hip impact configuration (F = 4.69, p = 0.016). On average, the absorbed energy was 62% greater in posteriolateral than anteriolateral impact (0.92 versus 0.57 J). However, the energy absorption did not differ between male and female (F = 0.91, p = 0.36). The force-deflection behavior of the femoral soft tissue during a fall has been recorded, providing insights on the potential protective benefits of the soft tissue covering during a fall.
Effects of different initial foot positions on kinematics, muscle activation patterns, and postural control during a sit-to-stand in younger and older adults.
Venue: Journal of biomechanics

Performing a sit-to-stand (STS) can be a challenging task for older adults because of age-related declines in neuromuscular strength and coordination. We investigated the effects of different initial foot positions (IFPs) on kinematics, muscle activation patterns, and balance control during a STS in younger and older adults.



Ten younger and ten older healthy adults participated in this study. Four symmetric IFPs were studied: (1) reference (REF), (2) toes-out with heels together (TOHT), (3) toes-out (TO), and (4) Wide. Lower-extremity muscle activation patterns and kinetic and kinematic data in the sagittal and frontal planes were measured.



The trunk forward-tilt angle and hip extension torque during uprising were smaller in TO and Wide for both age groups. Postural sway and center of pressure sway area were smallest in TO after completion of uprising with no difference between age groups. Adductor longus and gluteus medius activity was greater in TO than in the other IFPs, and older adults activated these muscles to a greater degree than younger adults.



Smaller trunk flexion angles with greater activation of the hip abductor and adductor muscles in TO contributed to improving postural stability during the STS.



STS training with a toes-out foot position could be an effective rehabilitation strategy for older adults to strengthen hip muscles that control medio-lateral balance required for balance during a STS.
Large magnitude of force leads to NO-mediated cell shrinkage in single osteocytes implying an initial apoptotic response.
Venue: Journal of biomechanics

Damage accumulation in the bone under continuous daily loading causes local mechanical overloading known to induce osteocyte apoptosis, which promotes bone resorption to repair bone damage. However, only a few studies have investigated the mechanism of apoptosis in mechanically overloaded osteocytes. As mechanically stimulated osteocytes produce nitric oxide (NO), which triggers apoptosis in various cell types, we aimed to elucidate the mechanism underlying apoptosis in mechanically overloaded osteocytes, focusing on intracellular NO. To investigate the effects of force magnitude on apoptosis and intracellular NO production, we isolated osteocytes from DMP1-EGFP mice and subjected them to quantitative local forces via fibronectin-coated micro beads targeting integrin on the cell surface using a magnetic tweezer. Cell shrinkage was microscopically examined, and intracellular NO production was visualized using DAR-4 M. Mechanical stimulation revealed relationships between force magnitude, apoptosis, and intracellular NO production. The application of a smaller force resulted in no significant cell shrinkage or intracellular NO production; however, a larger force caused a rapid increase in intracellular NO production followed by cell shrinkage. Besides, intracellular NOS (NO synthase) inhibition and NO donation revealed the pro-apoptotic roles of NO in osteocytes. L-NAME (NOS inhibitor)-treated cells displayed no significant shrinkage under a larger force, whereas SNP (NO donor)-treated cells showed cell shrinkage and Annexin V fluorescence, indicating apoptosis. Collectively, our study demonstrates that larger force leads to NO production-mediated osteocyte shrinkage, implying an initial apoptotic response and highlighting the importance of NO production in bone damage.
Video-based biomechanical analysis of an unexpected Achilles tendon rupture in an Olympic sprinter.
Venue: Journal of biomechanics

We used image-processing techniques to determine the moment (i.e., image frame) of the Achilles tendon (AT) rupture in an Olympic sprinter. This report may be unique due to the difficulty in conducting motion capture analyses during injury events. Our report includes one female Olympic sprinter, 29 years old (body mass: 56 kg, height: 1.68 m, and body mass index: 19.8 kg/m2) with a high-competitive profile history (2008 and 2012 Olympic Games participation; South American record holder in 100- and 200-m; Pan-American gold medalist in 200-m and 4 × 100-m relay) who suffered a complete AT rupture in the left leg while exercising in the final phase of rehabilitation following an Achilles tendinopathy in the contralateral limb. The greater dorsiflexion found at the moment of the injury and the delayed control of heel position indicated the presence of uncontrolled dorsiflexion, which potentially generated excessive eccentric stress over the tendon and, thus, the AT rupture. Here we discuss the relevance of lower leg alignment, the movements' characteristics, and the history of Achilles tendinopathy in the contralateral leg on the occurrence of the AT rupture.
Tandem ureteral stents drainage lowers renal pelvis pressure in malignant ureteral obstruction: Experimental and computational models.
Venue: Journal of biomechanics

Malignant ureteral obstruction may lead to impaired renal function and requires drainage by a percutaneous nephrostomy tube or an internal ureteric stent. Usage of stiff tandem ureteral stents may decrease stent failure rates. In this paper we combined computational and in vitro models to examine the flow in a malignant ureteral obstruction (MUO) managed by 4 methods of drainage: single soft stent, single stiff stent, soft tandem ureteral stents, and stiff tandem ureteral stents. Pressure at the renal pelvis was the primary outcome of the computational and in vitro models. Different drainage modalities were compared using ANCOVA. Results of computational and in vitro models agreed completely. Drainage by stiff tandem ureteral stents provides lower renal pelvis pressure levels compared with single and soft stents (p < 0.001), especially for high levels of external pressure. Usage of stiff tandem ureteral stents may decrease stent-failure rates and postpone the need for percutaneous nephrostomy tube insertion.
Relationships between tibial acceleration and ground reaction force measures in the medial-lateral and anterior-posterior planes.
Venue: Journal of biomechanics

Peak vertical tibial accelerations during running have shown strong correlations with vertical ground reaction force loading rates and some associations with injury. However, little attention has been given to tibial accelerations along the medial-lateral and anterior-posterior axes. Therefore, our purpose was to examine the correlation between peak tibial accelerations and ground reaction force loading rates in the medial-lateral and posterior directions. Eighteen recreational runners were recruited who ran with a rearfoot strike pattern (10 men/ 8 women, mean age (yrs) = 33 ± 11). Tibial accelerations and ground reaction forces were collected while participants ran on an instrumented treadmill at a self-selected speed. Correlations were developed for: a) peak medial and lateral accelerations with lateral and medial loading rates, respectively, b) peak anterior tibial accelerations and posterior loading rates. Significant correlations were found between tibial accelerations and loading rates in all planes. Peak medial tibial accelerations were correlated with lateral loading rates (Rs = 0.86, p < 0.001) and peak lateral tibial accelerations were correlated with peak medial loading rates (Rs = 0.91, p < 0.001). A lower correlation was found between anterior accelerations and posterior loading rates (Rs = 0.51, p = 0.030). Tibial accelerations in the medial-lateral plane seem to be a valid surrogate for the respective ground reaction force measures during running on a treadmill, explaining 74-83% of the variance in loading rates. However, with only 26% of the variance explained, the same may not be true for anterior tibial accelerations and posterior loading rates.
Mechanical properties of the different rotator cuff tendons in the rat are similarly and adversely affected by age.
Venue: Journal of biomechanics

Rotator cuff tendon tears and tendinopathies are common injuries affecting a large portion of the population and can result in pain and joint dysfunction. Incidence of rotator cuff tears significantly increases with advancing age, and up to 90% of these tears involve the supraspinatus. Previous literature has shown that aging can lead to inferior mechanics, altered composition, and changes in structural properties of the supraspinatus. However, there is little known about changes in supraspinatus mechanical properties in context of other rotator cuff tendons. Alterations in tendon mechanical properties may indicate damage and an increased risk of rupture, and thus, the purpose of this study was to use a rat model to define age-related alterations in rotator cuff tendon mechanics to determine why the supraspinatus is more susceptible to tears due to aging than the infraspinatus, subscapularis, and teres minor. Fatigue, viscoelastic, and quasi-static properties were evaluated in juvenile, adult, aged, and geriatric rats. Aging ubiquitously and adversely affected all rotator cuff tendons tested, particularly leading to increased stiffness, decreased stress relaxation, and decreased fatigue secant and tangent moduli in geriatric animals, suggesting a common intrinsic mechanism due to aging in all rotator cuff tendons. This study demonstrates that aging has a significant effect on rotator cuff tendon mechanical properties, though the supraspinatus was not preferentially affected. Thus, we are unable to attribute the aging-associated increase in supraspinatus tears to its mechanical response alone.
Microfluidic detection of human diseases: From liquid biopsy to COVID-19 diagnosis
Venue: Journal of Biomechanics

Microfluidic devices can be thought of as comprising interconnected miniaturized compartments performing multiple experimental tasks individually or in parallel in an integrated fashion. Due to its small size, portability, and low cost, attempts have been made to incorporate detection assays into microfluidic platforms for diseases such as cancer and infection. Some of these technologies have served as point-of-care and sample-to-answer devices. The methods for detecting biomarkers in different diseases usually share similar principles and can conveniently be adapted to cope with arising health challenges. The COVID-19 pandemic is one such challenge that is testing the performance of both our conventional and newly-developed disease diagnostic technologies. In this mini-review, we will first look at the progress made in the past few years in applying microfluidics for liquid biopsy and infectious disease detection. Following that, we will use the current pandemic as an example to discuss how such technological advancements can help in the current health challenge and better prepare us for future ones.