Local experience of laboratory activities in a BS physical therapy course: integrating sEMG and kinematics technology with active learning across six cohorts.

Introduction: Integrating technology and active learning methods into Laboratory activities would be a transformative educational experience to familiarize physical therapy (PT) students with STEM backgrounds and STEM-based new technologies. However, PT students struggle with technology and feel comfortable memorizing under expositive lectures. Thus, we described the difficulties, uncertainties, and advances observed by faculties on students and the perceptions about learning, satisfaction, and grades of students after implementing laboratory activities in a PT undergraduate course, which integrated surface-electromyography (sEMG) and kinematic technology combined with active learning methods. Methods: Six cohorts of PT students (n = 482) of a second-year PT course were included. The course had expositive lectures and seven laboratory activities. Students interpreted the evidence and addressed different motor control problems related to daily life movements. The difficulties, uncertainties, and advances observed by faculties on students, as well as the students' perceptions about learning, satisfaction with the course activities, and grades of students, were described. Results: The number of students indicating that the methodology was "always" or "almost always," promoting creative, analytical, or critical thinking was 70.5% [61.0-88.0%]. Satisfaction with the whole course was 97.0% [93.0-98.0%]. Laboratory grades were linearly associated to course grades with a regression coefficient of 0.53 and 0.43 R-squared (p < 0.001). Conclusion: Integrating sEMG and kinematics technology with active learning into laboratory activities enhances students' engagement and understanding of human movement. This approach holds promises to improve teaching-learning processes, which were observed consistently across the cohorts of students.

Static and dynamic stress analysis of different crown materials on a titanium base abutment in an implant-supported single crown: a 3D finite element analysis.

BACKGROUND: This Finite Element Analysis was conducted to analyze the biomechanical behaviors of titanium base abutments and several crown materials with respect to fatigue lifetime and stress distribution in implants and prosthetic components. METHODS: Five distinct designs of implant-supported single crowns were modeled, including a polyetheretherketone (PEEK), polymer-infiltrated ceramic network, monolithic lithium disilicate, and precrystallized and crystallized zirconia-reinforced lithium silicates supported by a titanium base abutment. For the static load, a 100 N oblique load was applied to the buccal incline of the palatal cusp of the maxillary right first premolar. The dynamic load was applied in the same way as in static loading with a frequency of 1 Hz. The principal stresses in the peripheral bone as well as the von Mises stresses and fatigue strength of the implants, abutments, prosthetic screws, and crowns were assessed. RESULTS: All of the models had comparable von Mises stress values from the implants and abutments, as well as comparable maximum and minimum principal stress values from the cortical and trabecular bones. The PEEK crown showed the lowest stress (46.89 MPa) in the cervical region. The prosthetic screws and implants exhibited the highest von Mises stress among the models. The lithium disilicate crown model had approximately 9.5 times more cycles to fatique values for implants and 1.7 times more cycles to fatique values for abutments than for the lowest ones. CONCLUSIONS: With the promise of at least ten years of clinical success and favorable stress distributions in implants and prosthetic components, clinicians can suggest using an implant-supported lithium disilicate crown with a titanium base abutment.

Unanticipated mid-flight external trunk perturbation increased frontal plane ACL loading variables during sidestep cuttings.

Unanticipated trunk perturbation is commonly observed when anterior cruciate ligament (ACL) injuries occur during direction-changing manoeuvres. This study aimed to quantify the effect of mid-flight medial-lateral external trunk perturbation directions/locations on ACL loading variables during sidestep cuttings. Thirty-two recreational athletes performed sidestep cuttings under combinations of three perturbation directions (no-perturbation, ipsilateral-perturbation, and contralateral-perturbation relative to the cutting leg) and two perturbation locations (upper-trunk versus lower-trunk). The pushing perturbation was created by customised devices releasing a slam ball to contact participants near maximum jump height prior to cutting. Perturbation generally resulted in greater peak vertical ground reaction force and slower cutting velocity. Upper-trunk contralateral perturbation showed the greatest lateral trunk bending away from the travel direction, greatest peak knee flexion and abduction angles, and greatest peak internal knee adduction moments compared to other conditions. Such increased ACL loading variables were likely due to the increased lateral trunk bending and whole-body horizontal velocity away from the cutting direction caused by the contralateral perturbation act at the upper trunk. The findings may help understand the mechanisms of indirect contact ACL injuries and develop effective cutting techniques for ACL injury prevention.

[Biomechanics of diabetic vitreopapillary traction syndrome]. / Biomekhanika diabeticheskogo vitreopapillyarnogo traktsionnogo sindroma.

Diabetic vitreopapillary traction syndrome (VPT) is a variant of diabetic retinopathy (DR) that can lead to vision loss in advanced stages. This review reports on the biomechanics of the vitreous in the pathogenesis of proliferative DR, in particular diabetic VPT. The article analyzes and summarizes literature data, presents the views of different authors on this problem, and provides the results of Russian and foreign scientific research on this pathology. It is concluded that further research in this area can lead to a significant improvement in the results of therapy, timely diagnosis, and preservation of vision in patients with DR.

A finite element model of human hindfoot and its application in supramalleolar osteotomy.

BACKGROUND: The majority of the ankle osteoarthritis cases are posttraumatic and affect younger patients with a longer projected life span. Hence, joint-preserving surgery, such as supramalleolar osteotomy becomes popular among young patients, especially those with asymmetric arthritis due to alignment deformities. However, there is a lack of biomechanical studies on postoperative evaluation of stress at ankle joints. We aimed to construct a verifiable finite element model of the human hindfoot, and to explore the effect of different osteotomy parameters on the treatment of varus ankle arthritis. METHODS: The bones of the hindfoot are reconstructed using normal CT tomography data from healthy volunteers, while the cartilages and ligaments are determined from the literature. The finite element calculation results are compared with the weight-bearing CT(WBCT) data to validate the model. By setting different model parameters, such as the osteotomy height (L) and the osteotomy distraction distance (h), the effects of different surgical parameters on the contact stress of the ankle joint surface are compared. FINDINGS: The alignment and the deformation of hindfoot bones as determined by the finite element analysis aligns closely with the data obtained from WBCT. The maximum contact stress of the ankle joint surface calculated by this model increases with the increase of the varus angle. The maximum contact stresses as a function of the L and h on of the ankle joint surface are determined. INTERPRETATION: The relationship between surgical parameters and stress at the ankle joint in our study could further help guiding the planning of the supramalleolar osteotomy according to the varus/valgus alignment of the patients.

A biomechanical study to optimize superior capsular reconstruction operative technique.

Background: The goals of this study were to optimize superior capsular reconstruction by assessing the relative fixation strength of 4 suture anchors; evaluating 3 glenoid neck locations for fixation strength and bone mineral density (BMD); determining if there is a correlation between BMD and fixation strength; and determining which portal sites have optimal access to the posterosuperior and anterosuperior glenoid neck for anchor placement. Methods: Twenty cadaveric specimens were randomized into 4 groups: all-suture anchor (FiberTak), conventional 3.0-mm knotless suture anchor (SutureTak), 3.9-mm knotless PEEK (polyetheretherketone) Corkscrew anchor, and 4.5-mm Bio-Corkscrew anchor. Each specimen was prepared with 3 anchors into the glenoid: an anterosuperior anchor, superior anchor, and posterosuperior anchor. All anchors were inserted into the superior glenoid neck 5 mm from the glenoid rim. A materials testing system performed cyclic testing (250 cycles) followed by load-to-failure testing at 12.5 mm/s. Cyclic elongation, first cycle excursion, maximum load, and stiffness were recorded. Using custom software, BMD was calculated at each anchor location. This software was also used to assess access to the posterosuperior and anterosuperior glenoid neck from standard arthroscopic portal positions. Results: There was no significant difference in cyclic elongation (P = .546), first cycle excursion (P = .476), maximum load (P = .817), or stiffness (P = .309) among glenoid anchor positions. Cyclic elongation was significantly longer in the PEEK Corkscrew group relative to the other implants (P ≤ .002). First cycle excursion was significantly greater in the FiberTak group relative to all other implants (P ≤ .008). For load-to-failure testing, the Bio-Corkscrew group achieved the highest maximum load (P ≤ .001). No other differences in cyclic or failure testing were observed between the groups. No differences in stiffness testing were observed (P = .133). The superior glenoid rim had the greatest BMD (P = .003), but there was no correlation between BMD and cyclic/load outcomes. The posterior portal (80% of specimens) and the anterior portal (60% of specimens) demonstrated the best access to the posterosuperior and anterosuperior glenoid neck, respectively. Conclusion: The 4.5-mm Bio-Corkscrew anchor provided the most robust fixation to the glenoid during superior capsular reconstruction as it demonstrated the strongest maximum load, had minimal elongation, had minimal first cycle excursion, and did not fail during cyclic testing. The superior glenoid neck had the highest BMD; however, there was no correlation between BMD or glenoid anchor location and biomechanical outcomes. The posterior portal and anterior portal provided optimal access to the posterosuperior glenoid neck and anterosuperior glenoid neck, respectively.

Ontogenetic changes in jaw leverage and skull shape in tufted and untufted capuchins.

The ontogeny of feeding is characterized by shifting functional demands concurrent with changes in craniofacial anatomy; relationships between these factors will look different in primates with disparate feeding behaviors during development. This study examines the ontogeny of skull morphology and jaw leverage in tufted (Sapajus) and untufted (Cebus) capuchin monkeys. Unlike Cebus, Sapajus have a mechanically challenging diet and behavioral observations of juvenile Sapajus suggest these foods are exploited early in development. Landmarks were placed on three-dimensional surface models of an ontogenetic series of Sapajus and Cebus skulls (n = 53) and used to generate shape data and jaw-leverage estimates across the tooth row for three jaw-closing muscles (temporalis, masseter, medial pterygoid) as well as a weighted combined estimate. Using geometric morphometric methods, we found that skull shape diverges early and shape is significantly different between Sapajus and Cebus throughout ontogeny. Additionally, jaw leverage varies with age and position on the tooth row and is greater in Sapajus compared to Cebus when calculated at the permanent dentition. We used two-block partial least squares analyses to identify covariance between skull shape and each of our jaw muscle leverage estimates. Sapajus, but not Cebus, has significant covariance between all leverage estimates at the anterior dentition. Our findings show that Sapajus and Cebus exhibit distinct craniofacial morphologies early in ontogeny and strong covariance between leverage estimates and craniofacial shape in Sapajus. These results are consistent with prior behavioral and comparative work suggesting these differences are a function of selection for exploiting mechanically challenging foods in Sapajus, and further emphasize that these differences appear quite early in ontogeny. This research builds on prior work that has highlighted the importance of understanding ontogeny for interpreting adult morphology.

3D kinematics of tibiotalar motion in patients with mobile bearing and fixed bearing total ankle arthroplasty: In vivo videofluoroscopic feasibility study.

BACKGROUND: As total ankle arthroplasty (TAA) is an increasingly common surgical intervention for patients with end-stage ankle arthritis, there is a need to better understand the dynamic performance of prosthetic implants during activities of daily living. Our purpose was to quantify and compare relative tibiotalar motion during gait in persons with a fixed-bearing (FB) and mobile-bearing (MB) total ankle arthroplasty. We hypothesized a FB prosthesis would have lower tibiotalar range of motion (ROM). METHODS: Patients at least 12 months postoperative with either a FB (n=5) or MB (n=3) total ankle arthroplasty were tested. We used high-speed biplanar videoradiography to quantify tibiotalar kinematics during self-selected gait. Angular and linear ROM in three axes were compared between the groups. RESULTS: ROM for dorsiflexion-plantarflexion, internal-external rotation, and inversion-eversion angles in FB subjects averaged 7.47±4.05°, 7.39±3.63°, and 4.51±2.13°, respectively. ROM in MB subjects averaged 6.74±2.04°, 6.28±4.51°, and 5.68±2.81°, respectively. Linear ROM along anteroposterior, mediolateral, and superior-inferior axes in FB subjects averaged 1.47±2.07 mm, 1.13±1.49 mm, and 0.28±0.30 mm, respectively. Linear ROM in MB subjects averaged 0.68±1.44 mm, 0.60±1.41 mm, and 0.20±0.13 mm, respectively. We found no significant difference between the two groups for any of these ROM parameters (p>0.05). CONCLUSION: Total ankle arthroplasty using either FB or MB design appears to confer similar ankle motion during the gait cycle in this biplanar fluoroscopic model. LEVEL OF EVIDENCE: Level IV, case series.

Biomechanics of conventional and miniscrew-assisted rapid palatal expansion.

Posterior Crossbite is a common condition resulting because of transverse maxillary deficiency. The growth of the craniofacial complex finishes first in the transverse dimension, followed by sagittal and vertical dimensions. Conventional rapid palatal expansion (RPE) appliances are commonly used to correct transverse maxillary deficiency. Although RPE is efficient in correcting posterior crossbite, it results in dental side effects such as buccal tipping of maxillary molars, root resorption, bone dehiscence, and relapse. Mini-implant-assisted RPE has been introduced to increase the skeletal effects of expansion especially in patients with increased maturation and greater interdigitation of midpalatal suture. This article will review the biomechanics of RPE and mini-implant-assisted RPE. Additionally, the different designs of MARPE and the long-term clinical effects of expansion appliances will also be discussed in detail.

Biomechanical evaluation of various rigid internal fixation modalities for condylar-base-associated multiple mandibular fractures: A finite element analysis.

Condylar-base-associated multiple mandibular fractures are more prevalent than single ones. Direct trauma to mandibular symphysis, body or angle are prone to induce indirect condylar fracture. However, little is known about the effects of various rigid internal fixation modalities in condylar base for relevant multiple mandibular fractures, especially when we are confused in the selection of operative approach. Within the finite element analysis, straight-titanium-plate implanting positions in condylar base contained posterolateral zone (I), anterolateral zone (II), and intermediate zone (III). Von Mises stress (SS) in devices and bone and mandibular displacement (DT) were solved, while maximum values (SSmax and DTmax) were documented. For rigid internal fixation in condylar-base-and-symphysis fractures, I + II modality exhibited least SSmax in screws and cortical bone and least DTmax, I + III modality exhibited least SSmax in plates. For rigid internal fixation in condylar-base-and-contralateral-body fractures, I + III modality exhibited least SSmax in screws and cortical bone, I + II modality exhibited least SSmax in plates and least DTmax. For rigid internal fixation in condylar-base-and-contralateral-angle fractures, I + III modality exhibited least DTmax. The findings suggest that either I + II or I + III modality is a valid guaranty for rigid internal fixation of condylar base fractures concomitant with symphysis, contralateral body or angle fractures.

A Review of Natural Fiber-Reinforced Composites for Lower-Limb Prosthetic Designs.

This paper presents a comprehensive review of natural fiber-reinforced composites (NFRCs) for lower-limb prosthetic designs. It covers the characteristics, types, and properties of natural fiber-reinforced composites as well as their advantages and drawbacks in prosthetic designs. This review also discusses successful prosthetic designs that incorporate NFRCs and the factors that make them effective. Additionally, this study explores the use of computational biomechanical models to evaluate the effectiveness of prosthetic devices and the key factors that are considered. Overall, this document provides a valuable resource for anyone interested in using NFRCs for lower-limb prosthetic designs.

3-Dimensional Biomechanics of Noncontact Anterior Cruciate Ligament Injuries in Male Professional Soccer Players.

BACKGROUND: The understanding of noncontact anterior cruciate ligament (ACL) injury causation in soccer has improved over the past decades. Bidimensional video analyses have significantly augmented our awareness, representing to date the only practical method to describe injury biomechanics. However, the extent of the problem continues to raise serious concerns. PURPOSE: To advance our understanding of the causal pathways leading to ACL injury with a large-scale reconstruction of 3-dimensional (3D) whole-body joint kinematics of injuries that occurred to male elite soccer players, as well as to compare the joint angle time course among situational patterns. STUDY DESIGN: Descriptive laboratory study. METHODS: A total of 33 consecutive noncontact and indirect contact ACL injuries that occurred in 6 national and 2 international professional leagues (seasons 2020-2021 to 2022-2023 until December 2022) were analyzed: (1) multiview noncoaxial television images were inspected; (2) multiple camera views were taken from 400 ms before the initial ground contact to 200 ms after the injury frame; (3) a size-matched pitch was modeled and used to calibrate cameras; (4) a 3D skeletal model was adjusted to fit the player's pose in each frame/view; and (5) poses were interpolated, and Euler joint angles were extracted. RESULTS: The authors reconstructed the 3D lower limb joint kinematic curves preceding and during ACL injuries in 33 cases; notably, a sudden external (up to 5°) and then internal knee rotation was observed after the initial contact and before the injury frame. The overall kinematics at injury were knee moderately flexed (45.9°± 21.7°), abducted (4.3°± 5.1°), and externally rotated (3.0°± 6.4°); trunk shallowly flexed (17.4°± 12.5°) and rotated and tilted toward the injured side; and hip flexed (32.0°± 18.7°), abducted (31.1°± 12.0°), and slightly internally rotated (6.6°± 12.2°). Variable behaviors were observed at the ankle level. CONCLUSION: Via reconstruction of the sequence of whole-body joint motion leading to injury, we confirmed the accepted gross biomechanics (dynamic valgus trend). This study significantly enriches the current knowledge on multiplanar kinematic features (transverse and coronal plane rotations). Furthermore, it was shown that ACL injuries in male professional soccer players manifest through distinct biomechanical footprints related to the concurrent game situation. CLINICAL RELEVANCE: Interventions aimed at reducing ACL injuries in soccer should consider that environmental features (ie, situational patterns) affect injury mechanics.

Biomechanical effects of muscle loading on early healing of femoral stem fractures: a combined musculoskeletal dynamics and finite element approach.

Femoral stem fractures (FST) are often accompanied by muscle injuries, however, what muscle injuries affect fracture healing and to what extent is unknown. The purpose of this study was to analyze the extent to which different muscles affect FST healing through a combined musculoskeletal dynamics and finite element approach. Modeling the lower extremity musculoskeletal system for 12 different muscle comprehensives. Muscle and joint reaction forces on the femur were calculated and these data were used as boundary conditions input to the FSTs model to predict the degree of muscle influence on fracture healing. Finally, we will investigate the extent to which muscle influences FST healing during knee flexion. Muscle and joint forces are highly dependent on joint motion and have a significant biomechanical influence on interfragmentary strain (IFS) healing. The psoas major (PM), gastrocnemius lateralis (GL) and gastrocnemius medialis (GM) muscles play a major role in standing, with GM > PM > GL, whereas the gluteus medius posterior (GMP), vastus intermedius (VI), vastus medialis (VM), vastus lateralis superior (VLS), and adductor magnus distalis (AMD) muscles play a major role in knee flexion, with VLS > VM > VI > AMD > GMP. Mechanical stimulus-controlled healing can be facilitated when the knee joint is flexed less than 20°. Different muscles exert varying degrees of influence on the healing of fractures. Therefore, comprehending the impact of particular muscles on fracture site tissue FST healing can aid orthopedic surgeons in formulating improved surgical and rehabilitation strategies.

Podiatric conditions observed in Special Olympics athletes: Contrasting data from a USA versus an international population.

OBJECTIVES: Persons with intellectual disabilities frequently have podiatric conditions. Findings from the 2018 United States Summer games (USA) venues are compared to those from athletes screened at the 2019 Special Olympics World Summer Games in Abu Dhabi, United Arab Emirates (UAE). METHODS: Data from Fit Feet screenings from 2445 United Arab Emirates (UAE) participants were compared to 1244 US participants. RESULTS: A sampling of results that reflect significant differences in findings between the USA cohort and Abu Dhabi cohort include ankle joint range of motion, excessive abduction, hallux abducto valgus and pes planus. The overall shoe to foot mismatch was found to be 52.2%. A professional referral was recommended 27.7% of the time in the USA data and 28.5% in the Abu Dhabi data. An urgent referral was requested 5.1% of the time for the USA data and 3.7% of the time in the Abu Dhabi data. CONCLUSION: Special Olympics athletes experience a greater prevalence of identifiable podiatric conditions as compared to the general population. Several of the conditions investigated in this study differed significantly between the international Special Olympics cohort and the USA cohort. Assessment of the feet of Special Olympics athletes can help to better appreciate the podiatric conditions in a population of individuals with intellectual disabilities. The variance identified between populations of Special Olympics athletes may be a reflection on the lack of standardization of conditions that are assessed for as well as the disparate characteristics of the clinical volunteers. Future Fit Feet events may wish to consider significant improvements in objectivity and standardization as it pertains to the conditions that are evaluated for in the Fit Feet exam.

Passive mechanical properties of adipose tissue and skeletal muscle from C57BL/6J mice.

Skeletal muscle and adipose tissue are characterized by unique structural features finely tuned to meet specific functional demands. In this study, we investigated the passive mechanical properties of soleus (SOL), extensor digitorum longus (EDL) and diaphragm (DIA) muscles, as well as subcutaneous (SAT), visceral (VAT) and brown (BAT) adipose tissues from 13 C57BL/6J mice. Thereto, alongside stress-relaxation assessments we subjected isolated muscles and adipose tissues (ATs) to force-extension tests up to 10% and 30% of their optimal length, respectively. Peak passive stress was highest in the DIA, followed by the SOL and lowest in the EDL (p < 0.05). SOL displayed also the highest Young's modulus and hysteresis among muscles (p < 0.05). BAT demonstrated highest peak passive stress and Young's modulus followed by VAT (p < 0.05), while SAT showed the highest hysteresis (p < 0.05). When comparing data across all six biological specimens at fixed passive force intervals (i.e., 20-40 and 50-70 mN), skeletal muscles exhibited significantly higher peak stresses and strains than ATs (p < 0.05). Young's modulus was higher in skeletal muscles than in ATs (p < 0.05). Muscle specimens exhibited slower force relaxation in the first phase compared to ATs (p < 0.05), while there was no significant difference in behavior between muscles and AT in the second phase of relaxation. The study revealed distinctive mechanical behaviors specific to different tissues, and even between different muscles and ATs. These variations in mechanical properties are likely such to optimize the specific functions performed by each biological tissue.

Influence of muscle activation on lumbar injury under a specific +Gz load.

PURPOSE: The aim of the present study was to analyze the influence of muscle activation on lumbar injury under a specific +Gz load. METHODS: A hybrid finite element human body model with detailed lumbar anatomy and lumbar muscle activation capabilities was developed. Using the specific +Gz loading acceleration as input, the kinematic and biomechanical responses of the occupant's lower back were studied for both activated and deactivated states of the lumbar muscles. RESULTS: The results indicated that activating the major lumbar muscles enhanced the stability of the occupant's torso, which delayed the contact between the occupant's head and the headrest. Lumbar muscle activation led to higher strain and stress output in the lumbar spine under +Gz load, such as the maximum Von-Mises stress of the vertebrae and intervertebral discs increased by 177.9% and 161.8%, respectively, and the damage response index increased by 84.5%. CONCLUSION: In both simulations, the occupant's risk of lumbar injury does not exceed 10% probability. Therefore, the activation of muscles could provide good protection for maintaining the lumbar spine and reduce the effect of acceleration in vehicle travel direction.

Compositional, Structural, and Biomechanical Properties of Three Different Soft Tissue-Hard Tissue Insertions: A Comparative Review.

Connective tissue attaches to bone across an insertion with spatial gradients in components, microstructure, and biomechanics. Due to regional stress concentrations between two mechanically dissimilar materials, the insertion is vulnerable to mechanical damage during joint movements and difficult to repair completely, which remains a significant clinical challenge. Despite interface stress concentrations, the native insertion physiologically functions as the effective load-transfer device between soft tissue and bone. This review summarizes tendon, ligament, and meniscus insertions cross-sectionally, which is novel in this field. Herein, the similarities and differences between the three kinds of insertions in terms of components, microstructure, and biomechanics are compared in great detail. This review begins with describing the basic components existing in the four zones (original soft tissue, uncalcified fibrocartilage, calcified fibrocartilage, and bone) of each kind of insertion, respectively. It then discusses the microstructure constructed from collagen, glycosaminoglycans (GAGs), minerals and others, which provides key support for the biomechanical properties and affects its physiological functions. Finally, the review continues by describing variations in mechanical properties at the millimeter, micrometer, and nanometer scale, which minimize stress concentrations and control stretch at the insertion. In summary, investigating the contrasts between the three has enlightening significance for future directions of repair strategies of insertion diseases and for bioinspired approaches to effective soft-hard interfaces and other tough and robust materials in medicine and engineering.

A surgical technique for individual control of the muscles of the rabbit lower hindlimb.

Little is known regarding the precise muscle, bone and joint actions resulting from individual and simultaneous muscle activation(s) of the lower limb. An in situ experimental approach is described herein to control the muscles of the rabbit lower hindlimb, including the medial and lateral gastrocnemius, soleus, plantaris and tibialis anterior. The muscles were stimulated using nerve-cuff electrodes placed around the innervating nerves of each muscle. Animals were fixed in a stereotactic frame with the ankle angle set at 90 deg. To demonstrate the efficacy of the experimental technique, isometric plantarflexion torque was measured at the 90 deg ankle joint angle at a stimulation frequency of 100, 60 and 30 Hz. Individual muscle torque and the torque produced during simultaneous activation of all plantarflexor muscles are presented for four animals. These results demonstrate that the experimental approach was reliable, with insignificant variation in torque between repeated contractions. The experimental approach described herein provides the potential for measuring a diverse array of muscle properties, which is important to improve our understanding of musculoskeletal biomechanics.

Associations Between Hip Pathology, Hip and Groin Pain, and Injuries in Hockey Athletes: A Clinical Commentary.

Femoroacetabular impingement (FAI), particularly cam morphology, is highly prevalent among elite hockey athletes. Moreover, hip and groin pain has become a common issue in hockey, with approximately 50% of European professional athletes reported to experience a hip or groin problem during a season. While most athletes will not miss training or competition due to this, restricted competitive performance and increased risk of reduced physical and psychological well-being are likely. Recent research suggests that the development of cam morphology is related to the repetitive shear stresses experienced at the hip joint during adolescence from skating. This condition likely increases the potential for intra-articular and extra-articular injuries in these athletes later in their careers. Research also indicates that the hip joint mechanics during forward skating substantially increase the possibility of sustaining a labral tear compared to other sports. Such an injury can increase femoral head movement within the joint, potentially causing secondary damage to the iliofemoral ligament, ligamentum teres and joint capsule. These injuries and the high density of nociceptors in the affected structures may explain the high prevalence of hip and groin pain in hockey athletes. Compensatory adaptations, such as reduced hip strength, stability, and range-of-motion (ROM) likely increase the opportunity for core muscle injuries and hip flexor and adductor injuries. Specifically, the limited hip ROM associated with cam morphology appears to exacerbate the risk of these injuries as there will be an increase in pubic symphysis stress and transverse strain during rotational movements. It is hoped that this article will assist practitioners currently working with hockey athletes to develop evidence-informed monitoring strategies and training interventions, aimed at reducing the incidence and severity of hip and groin problems, ultimately enhancing athlete performance and well-being. Therefore, the purpose of this clinical commentary was to examine current evidence on common hip pathologies in hockey athletes, exploring potential associations between hip and groin pain and the biomechanics of hockey activities. Level of Evidence: 5.

Individualized Technique Feedback for Instant Technique Improvements and Knee Abduction Moment Reductions - A New Approach for 'Sidestepping' ACL Injuries?

Background: Sidestep cutting technique is highly individual and has been shown to influence knee joint loading. However, studies assessing whether individualized technique feedback improves technique and ACL injury-relevant knee joint loads instantly in a sport-specific task are lacking. Purpose: To determine the instant effects of individualized augmented technique feedback and instructions on technique and the peak external knee abduction moment (pKAM) in a handball-specific sidestep cut. Additionally, to determine the effects of technique modifications on the resultant ground reaction force and its frontal plane moment arm to the knee joint center. Study Design: Controlled laboratory cohort study. Methods: Three-dimensional biomechanics of 48 adolescent female handball players were recorded during a handball-specific sidestep cut. Following baseline cuts to each side, leg-specific visual and verbal technique feedback on foot strike angle, knee valgus motion, or vertical impact velocity using a hierarchically organized structure accounting for the variables' association with performance was provided. Subsequently, sidestep cuts were performed again while verbal instructions were provided to guide technique modifications. Combined effects of feedback and instructions on technique and pKAM as well as on the resultant ground reaction force and its frontal plane moment arm to the knee joint center were assessed. Results: On average, each targeted technique variable improved following feedback and instructions, leading to instant reductions in pKAM of 13.4% to 17.1%. High inter-individual differences in response to feedback-instruction combinations were observed. These differences were evident in both the adherence to instructions and the impact on pKAM and its components. Conclusion: Most players were able to instantly adapt their technique and decrease ACL injury-relevant knee joint loads through individualized augmented technique feedback, thereby potentially reducing the risk of injury. More research is needed to assess the retention of these adaptations and move towards on-field technique assessments using low-cost equipment. Level of Evidence: Level 3.