Hip Angles Research Articles

Validity and Reliability of Handheld Dynamometry to Assess Isometric Hamstrings and Quadriceps Strength at Varying Muscle Lengths.

The hamstrings are the most commonly injured muscle in sports and are especially injury prone in lengthened positions. Measuring knee muscle strength in such positions could be relevant to establish injury risk. Handheld dynamometry has been shown to be a valid, reliable, and practical tool to measure isometric muscle strength clinically. The aim of this study was to assess the validity and reliability of the assessment of isometric knee muscle strength with a handheld dynamometer (HHD) at various muscle lengths, by modifying the hip and knee angles during testing. Concurrent validity and test-retest reliability. Thirty young healthy participants were recruited. Hamstring and quadriceps isometric strength was measured with a HHD and with an isokinetic dynamometer, over 2 testing sessions, in a randomized order. Isometric strength was measured on the right lower limb in 6 different positions, with the hip at either 0° or 80° of flexion and the knee at either 30°, 60°, or 90° of flexion. Pearson and Spearman correlations were used to assess the validity, and intraclass correlation coefficients were calculated to establish the test-retest reliability of the HHD. Good to excellent reliability and moderate to high validity were found in all the tested muscle length positions, except for the hamstrings in a seated position with the knee extended at 30°. The use of a HHD is supported in the clinical setting to measure knee muscle strength at varying muscle lengths in healthy adults, but not for the hamstrings in a lengthened position (hip flexed and knee extended). These results will have to be confirmed in sport-specific populations.

Reduced trunk movement control during motor dual-tasking in older adults

Older adults have a decreased trunk movement control which is linked to their higher fall risk. While motor/cognitive dual-tasking deteriorates balance and walking in older adults, there is limited understanding on how trunk kinematics and kinetics are affected by dual-tasking in scenarios where falls can occur. Therefore, the purpose of the study was to determine the impacts of a challenging motor dual-task, specifically obstacle avoidance during walking, on trunk and lower-body kinematics and kinetics of older adults compared to young adults. The study captured three-dimensional kinematic and kinetic data from 12 young adults and 10 older adults as they walked on a treadmill and stepped over an obstacle with both legs. The study analyzed trunk, hip, knee, and ankle angles and torques. Trunk torque was further broken down to trunk muscle torque, gravitational torque, and inertia torque. A linear mixed effects model was used to investigate the difference in each variable between the two groups. Older adults exhibited significantly increased trunk flexion angle and trunk extension muscle torque compared to young adults, with the trunk being the only segment/joint showing differences in both kinematics and kinetics. Trunk torque breakdown analysis revealed that larger trunk flexion led to a larger gravitational torque, which contributed to an increased compensatory trunk muscle torque. Moreover, older adults' less controlled trunk flexion during weight shifting from trail leg to the lead leg, necessitated a compensatory trunk deceleration during trail leg obstacle avoidance which was achieved by generating additional increase in trunk muscle torque. The study demonstrated that motor dual-tasking has the most negative effects on trunk control in older adults compared to young adults. This exposes older adults to a higher fall risk. Therefore, future work should focus on supporting trunk control during daily multi-tasking conditions where falls can occur.

Walking with unilateral ankle-foot unloading: a comparative biomechanical analysis of three assistive devices

BackgroundFoot and ankle unloading is essential in various clinical contexts, including ulcers, tendon ruptures, and fractures. Choosing the right assistive device is crucial for functionality and recovery. Yet, research on the impact of devices beyond crutches, particularly ankle-foot orthoses (AFOs) designed to unload the ankle and foot, is limited. This study investigates the effects of three types of devices—forearm crutches, knee crutch, and AFO—on biomechanical, metabolic, and subjective parameters during walking with unilateral ankle-foot unloading.MethodsTwenty healthy participants walked at a self-selected speed in four conditions: unassisted able-bodied gait, and using three unloading devices, namely forearm crutches, iWalk knee crutch, and ZeroG AFO. Comprehensive measurements, including motion capture, force plates, and metabolic system, were used to assess various spatiotemporal, kinematic, kinetic, and metabolic parameters. Additionally, participants provided subjective feedback through questionnaires. The conditions were compared using a within-subject crossover study design with repeated measures ANOVA.ResultsSignificant differences were found between the three devices and able-bodied gait. Among the devices, ZeroG exhibited significantly faster walking speed and lower metabolic cost. For the weight-bearing leg, ZeroG exhibited the shortest stance phase, lowest braking forces, and hip and knee angles most similar to normal gait. However, ankle plantarflexion after push-off using ZeroG was most different from normal gait. IWalk and crutches caused significantly larger center-of-mass mediolateral and vertical fluctuations, respectively. Participants rated the ZeroG as the most stable, but more participants complained it caused excessive pressure and pain. Crutches were rated with the highest perceived exertion and lowest comfort, whereas no significant differences between ZeroG and iWalk were found for these parameters.ConclusionsSignificant differences among the devices were identified across all measurements, aligning with previous studies for crutches and iWalk. ZeroG demonstrated favorable performance in most aspects, highlighting the potential of AFOs in enhancing gait rehabilitation when unloading is necessary. However, poor comfort and atypical sound-side ankle kinematics were evident with ZeroG. These findings can assist clinicians in making educated decisions about prescribing ankle-foot unloading devices and guide the design of improved devices that overcome the limitations of existing solutions.

A Comparison of the Immediate Effects of Verbal and Virtual Reality Feedback on Gait in Children with Cerebral Palsy.

Different types of feedback are used during gait training in children with cerebral palsy (CP), including verbal (VB) and virtual reality (VR) feedback. Previous studies on VR feedback showed positive effects on the targeted gait parameter. However, both positive and negative side effects on other parameters were seen as well. The literature on the effect of VB feedback is lacking and, to our knowledge, both feedback methods have not yet been compared. In this monocentric study with a single-session intervention protocol, children with CP completed a training session on the Gait Real-Time Analysis Interactive Lab (GRAIL) and received both VB and VR feedback on hip extension, in randomized order. Outcome parameters were continuous gait curves of sagittal kinematics and hip kinetics, specific features of hip angle and moment, sagittal gait variable scores and gait profile scores. Improvement of the targeted gait parameter was seen both after VB and VR feedback, with a small advantage for VR over VB feedback. Furthermore, positive side effects on knee and ankle sagittal kinematics were seen. However, the overall gait profile score did not improve, most likely due to negative compensatory strategies. In conclusion, children with CP can adapt gait in response to both VB and VR feedback, with VR feedback producing a slightly better effect. Due to secondary effects on parameters other than the targeted parameter, the overall gait did not improve.

Either Autonomy Support or Enhanced Expectancies Delivered Via Virtual-Reality Benefits Frontal-Plane Single-Leg Squatting Kinematics.

Our purpose in this study was to determine the effects of a virtual reality intervention delivering specific motivational motor learning manipulations of either autonomy support (AS) or enhanced expectancies (EE) on frontal plane single-leg squatting kinematics. We allocated 45 participants (21 male, 24 female) demonstrating knee, hip, and trunk frontal plane mechanics associated with elevated anterior cruciate ligament injury risk to one of three groups (control, AS, or EE). Participants mimicked an avatar performing five sets of eight repetitions of exemplary single-leg squats. AS participants were given the added option of choosing the color of their avatar. EE participants received real-time biofeedback in the form of green highlights on the avatar that remained on as long as the participant maintained pre-determined 'safe' frontal plane mechanics. We measured peak frontal plane knee, hip, and trunk angles before (baseline) and immediately following (post) the intervention. The control group demonstrated greater increases in knee abduction angle (Δ = +2.3°) than did the AS (Δ = +0.1°) and EE groups (Δ = -0.4°) (p = .003; η2p = .28). All groups demonstrated increased peak hip adduction (p = .01, ηp2 = .18) (control Δ = +1.5°; AS Δ = +3.2°; EE Δ = +0.7°). Hip adduction worsened in all groups. AS and EE motivation strategies appeared to mitigate maladaptive frontal plane knee mechanics.

Computational study of extrinsic factors affecting ACL strain during single-leg jump landing

BackgroundNon-contact anterior cruciate ligament (ACL) injuries are a major concern in sport-related activities due to dynamic knee movements. There is a paucity of finite element (FE) studies that have accurately replicated the knee geometry, kinematics, and muscle forces during dynamic activities. The objective of this study was to develop and validate a knee FE model and use it to quantify the relationships between sagittal plane knee kinematics, kinetics and the resulting ACL strain.Methods3D images of a cadaver knee specimen were segmented (bones, cartilage, and meniscus) and meshed to develop the FE model. Knee ligament insertion sites were defined in the FE model via experimental digitization of the specimen’s ligaments. The response of the model was validated against multiple physiological knee movements using published experimental data. Single-leg jump landing motions were then simulated on the validated model with muscle forces and kinematic inputs derived from motion capture and rigid body modelling of ten participants.ResultsThe maximum ACL strain measured with the model during jump landing was 3.5 ± 2.2%, comparable to published experimental results. Bivariate analysis showed no significant correlation between body weight, ground reaction force and sagittal plane parameters (such as joint flexion angles, joint moments, muscle forces, and joint velocity) and ACL strain. Multivariate regression analysis showed increasing trunk, hip and ankle flexion angles decreases ACL strain (R2 = 90.04%, p < 0.05).ConclusionsSoft landing decreases ACL strain and the relationship could be presented through an empirical equation. The model and the empirical relation developed in this study could be used to better predict ACL injury risk and prevention strategies during dynamic activities.

Jump Landing Kinematics: Establishing Normative Ranges For Male And Female Athletes.

Lower extremity joint (LE) kinematics during landing tasks are important predictors of injury risk and performance outcomes in athletes. To establish sex-related differences and normative ranges for LE kinematics during the jump-landing task in a large cohort of healthy military service academy cadets. Cross-Sectional Study. US Air Force, Naval, and Military Academies. 5308 cadets (2062 females [38.8%]). Sex-related differences in LE kinematics were analyzed using independent samples t-tests. Mean differences (MD) and effect sizes (d) were reported for interpretability. Normative ranges for hip and knee joint angles were established separately for males and females at initial contact (IC) and 50% of the stance phase. Compared to males, moderate effect sizes (d ≥ .5) were observed for knee external rotation (negative value) where females displayed greater motion at IC and at 50% stance (MD: - 3.9˚ and -5.0˚, respectively, p < .001). The following findings were of small effect size (.2 ≥ d > .5). Females exhibited less knee and hip flexion at IC (MD: -1.8˚ and -0.5˚, respectively, p < .001) and at 50% stance (MD: -4.1˚ and -4.6˚, respectfully, p < .001). This was accompanied by females having greater knee valgus (negative value) and hip adduction at IC (MD: -2.2˚ and 1.06˚, respectively, p < .001) and at 50% stance (MD: -3.2˚ and 1.8˚, respectfully, p < .001). This study establishes normative ranges for LE kinematics during the jump-landing task in a large cohort of healthy military service academy cadets entering their first year. Sex- related differences in LE kinematics were observed, highlighting the importance of considering sex as a factor in the evaluation of lower extremity movement quality and management of injury risk.

Validity Verification of Human Pose-Tracking Algorithms for Gait Analysis Capability.

Two-dimensional (2D) clinical gait analysis systems are more affordable and portable than contemporary three-dimensional (3D) clinical models. Using the Vicon 3D motion capture system as the standard, we evaluated the internal statistics of the Imasen and open-source OpenPose gait measurement systems, both designed for 2D input, to validate their output based on the similarity of results and the legitimacy of their inner statistical processes. We measured time factors, distance factors, and joint angles of the hip and knee joints in the sagittal plane while varying speeds and gaits during level walking in three in-person walking experiments under normal, maximum-speed, and tandem scenarios. The intraclass correlation coefficients of the 2D models were greater than 0.769 for all gait parameters compared with those of Vicon, except for some knee joint angles. The relative agreement was excellent for the time-distance gait parameter and moderate-to-excellent for each gait motion contraction range, except for hip joint angles. The time-distance gait parameter was high for Cronbach's alpha coefficients of 0.899-0.993 but low for 0.298-0.971. Correlation coefficients were greater than 0.571 for time-distance gait parameters but lower for joint angle parameters, particularly hip joint angles. Our study elucidates areas in which to improve 2D models for their widespread clinical application.

SEMG data driven-based anti-disturbance control enables adaptive interaction of lower limb rehabilitation exoskeleton

The efficient human–machine interaction control is the core of human–machine integration, which can improve the tracking accuracy of the lower limb rehabilitation exoskeleton system and the compliance of human–machine cooperative movement. However, the non-ideal factors such as mechanical friction, model uncertainties, iteration errors and external interference in the training process undoubtedly bring potential dangers to the safety of rehabilitation training. Consequently, to escape unnecessary damage caused by external disturbances (especially the unbounded disturbances) during rehabilitation training, a noise-suppressing zeroing neural network human–machine interaction controller is developed in this work, which is based on the constructed human–machine coupling dynamic model and the active motion intention (active torque) of the subject identified by exploiting the deep convolutional neural network. The simulation experiments and statistical analyses verify that the present noise-suppressing zeroing neural network controller can be applied to monitor the lower limb rehabilitation exoskeleton for assisting the subjects in various task with the external disturbances,and the average root mean square error of the hip, knee and ankle joints’ angles are 0.0015rad, 0.0051rad and 0.0056rad, respectively. Furthermore, a novel model predictive control is developed and analyzed based on noise-suppressing zeroing neural network controller, which can effectively constrain the angle and angular velocity of the lower limb rehabilitation exoskeleton. The root mean square errors of hip, knee and ankle joint angle are 0.0032rad, 0.0078rad, and 0.0085rad, respectively. Finally, the platform experiment verifies that the proposed controllers can be utilized to control the lower limb rehabilitation exoskeleton to assist the subjects in rehabilitation training.

The small screw-apex distance is potentially associated with femoral head osteonecrosis in adults with femoral neck fractures treated by closed reduction and percutaneous 3 parallel cannulated screws

ObjectiveFemoral neck fractures (FNFs) are among the most common fractures in elderly individuals. Surgery is the main treatment for FNFs, and osteonecrosis of the femoral head (ONFH) is one of the unacceptable complications. This study aimed to assess both the clinical and radiological outcomes in patients with FNFs treated with three parallel cannulated screws and to identify relationship between screws position and ONFH.Patients and methodsA total of 100 patients who were treated with closed reduction and fixed with 3 parallel cannulated screws met the inclusion criteria between January 2014 and December 2020 at authors’ institution. The follow-up duration, age, sex, affected side, and injury-to-surgery interval were collected; the neck-shaft angle of both hips, screw-apex distance (SAD) and the tip-apex distance (TAD)were measured; and the Garden classification, quality of reduction and presence of ONFH were evaluated.ResultsThe sample consisted of 37 males and 63 females, with 60 left and 40 right hips affected. The mean age of patients was 54.93 ± 12.24 years, and the mean follow-up was 56.3 ± 13.38 months. The overall incidence of ONFH was 13%. No significant difference was observed in the incidence of ONFH by affected side, age, fracture displacement, injury-to-surgery interval, neck-shaft angle deviation, or reduction quality. The SAD was significantly shorter in ONFH patients than in normal patients for all three screws (p = 0.02, 0.02, and 0.01, respectively).ConclusionsThe short SAD of all screws is associated with femoral head necrosis of FNFs treated with 3 cannulated screws. The short SAD indicated that screws malpositioning in the weight-bearing area of the femoral head, potentially harming the blood supply and compromising the anchorage of the primary compressive trabeculae in this region.

Biomechanical Comparison of Pediatric Female Ballet Dancers With and Without Pain

BACKGROUND: Across all genres of dance, studies have reported musculoskeletal injury in 20-84% of dancers with 95% reporting a history of musculoskeletal pain. Compared to other dance styles, ballet dancers specifically are most affected by musculoskeletal injuries. The purpose of this study is to compare movement patterns and muscle activity in pediatric female pre-professional dancers with and without self- reported pain, using the Patient-Reported Outcomes Measurement Information System pediatric numeric rating scale. We hypothesize dancers reporting pain will exhibit compensatory strategies, such as asymmetrical movement patterns and muscle activity, across a series of ballet movements. METHODS: A total of 55 female ballet dancers who train en pointe were seen for testing (age 14.4±1.9 years), with 34 dancers (62%) self-reported pain in the 7 days preceding testing. Biomechanical testing, performed in pointe shoes, included performance of static (5 classical ballet positions) and dynamic ballet movements (développé, arabesqué and grand jeté) while instrumented with surface electromyography (EMG) to capture muscle activity and inertial measurement (IMU) dual sensors on the trunk and lower extremities to capture movement patterns. The experimental setup allowed for measurement of trunk and lower extremity muscle activity, as well as trunk, hip, knee, and ankle joint angles in the sagittal, coronal, and transverse planes. Student’s t-test was used to compare the pain and no pain groups across all variables with statistical significance set to α=0.05. RESULTS: Movement patterns and EMG differences were seen between groups. During first and third positions, the right (non-barre sided) leg demonstrated less external knee rotation in the pain group (p≤0.05). In fifth position, the left (barre-sided) leg exhibited increased ankle flexion (p=0.048), reduced hip abduction (p=0.027), and reduced knee adduction (p=0.026) in the pain group. The pain group exhibited decreased trunk flexion/extension range-of-motion during the grand jeté (p=0.004), and increased trunk rotation range-of-motion when performing the arabesqué en pointe (p=0.034). Rectus femoris activation was reduced for the pain group on the left leg in fifth position (p&lt;0.03). The up leg in the pain group during the développé (flat) showed increased hamstring activation (p=0.04). CONCLUSION: Ballet dancers with pain exhibited differences in movement patterns while performing certain ballet movements, notably during fifth position, grand jeté, and arabesqué (en pointe). Additionally, dancers with pain exhibited reduced rectus femoris activation in fifth position and increased hamstring activation on the working leg during the développé (flat). Future work should investigate how movement patterns and muscle activation in ballet dancers vary by location and severity of reported pain.

Hip Joint Angular Values in Children with Bilateral Spastic Cerebral Palsy: A Comparison between Ambulatory and Nonambulatory Groups According to the Gross Motor Functional Classification System

Objective: The aim of this study was to compare the migration index (MI), femoral inclination angle (FIA), lateral center-edge angle (LCEA), and acetabular index (AI) values measured from hip joint radiographs of children with bilateral spastic cerebral palsy (CP) divided into ambulatory and nonambulatory groups according to the Gross Motor Functional Classification System with functional levels of children, and to examine their relationship with anthropometric measurements of the lower extremities. Materials and Methods: The present investigation encompassed the evaluation of 30 children afflicted with CP, through the conduction of hip joint radiographic assessments, which involved the right and left hip joints, the acquisition of images using MI, FIA, LCEA, and AI parameters, as well as measurement of lower-extremity anthropometric data. Results: A significant difference was found between ambulatory and nonambulatory groups in the left MI, FIA, and LCEA (P &lt; 0.05). In comparison of anthropometric measurements to height ratios, no significant difference was found, except for left ankle circumference and bi-iliac diameter measurements (P &gt; 0.05). Conclusion: The hip joint angular values of the ambulatory group were found to be within normal limits compared to those of the nonambulatory group. Although there were significant differences between hip joint angles in the two groups, there was no significant correlation with lower-extremity anthropometric measurements. It was concluded that hip joint angles were more pathological and prone to hip displacement in the nonambulatory group. This study revealed the importance of strategies to maintain and improve the functional capacity of children with CP.

Accuracy of conventional motion capture in measuring hip joint center location and hip rotations during gait, squat, and step-up activities

Accurate measurements of hip joint kinematics are essential for improving our understanding of the effects of injury, disease, and surgical intervention on long-term hip joint health. This study assessed the accuracy of conventional motion capture (MoCap) for measuring hip joint center (HJC) location and hip joint angles during gait, squat, and step-up activities while using dynamic biplane radiography (DBR) as the reference standard. Twenty-four young adults performed six trials of treadmill walking, six body-weight squats, and six step-ups within a biplane radiography system. Synchronized biplane radiographs were collected at 50 images per second and MoCap was collected simultaneously at 100 images per second. Bone motion during each activity was determined by matching digitally reconstructed radiographs, created from subject-specific CT-based bone models, to the biplane radiographs using a validated registration process. Errors in estimating HJC location and hip angles using MoCap were quantified by the root mean squared error (RMSE) across all frames of available data. The MoCap error in estimating HJC location was larger during step-up (up to 89.3 mm) than during gait (up to 16.6 mm) or squat (up to 31.4 mm) in all three anatomic directions (all p < 0.001). RMSE in hip joint flexion (7.2°) and abduction (4.3°) during gait was less than during squat (23.8° and 8.9°) and step-up (20.1° and 10.6°) (all p < 0.01). Clinical analysis and computational models that rely on skin-mounted markers to estimate hip kinematics should be interpreted with caution, especially during activities that involve deeper hip flexion.

The relationship between joint kinematic patterns during single-leg drop landing and perceived instability in individuals with chronic ankle instability

BackgroundPerceived instability is a primary symptom among individuals with chronic ankle instability. However, the relationship between joint kinematics during landing remains unclear. Therefore, we investigated the relationships between landing kinematics and perceived instability in individuals with chronic ankle instability. MethodsIn 32 individuals with chronic ankle instability, we recorded ankle, knee, and hip joint angles during a single-leg drop landing. Joint angle waveforms during 200 ms before and after initial contact were summarized into single values using two methods: peak joint angles and principal component scores via principal component analysis. Using Spearman's rank correlation coefficient (ρ), we examined the relationships of peak joint angles and principal component scores with the Cumberland Ankle Instability Tool score, with a lower score indicating a greater perceived instability (α = 0.05). FindingsThe second principal component scores of ankle angle in the horizontal and sagittal planes significantly correlated with the Cumberland Ankle Instability Tool score (Horizontal: ρ = 0.507, P = 0.003; Sagittal: ρ = −0.359, P = 0.044). These scores indicated the differences in the magnitude of angles before and after landing. Significant correlations indicated a greater perceived instability correlated with smaller internal rotation and plantarflexion before landing and smaller external rotation and dorsiflexion after landing. In contrast, no peak joint angles correlated with the Cumberland Ankle Instability Tool score (P > 0.05). InterpretationIn individuals with chronic ankle instability, ankle movements during landing associated with perceived instability may be a protective strategy before landing and potentially cause ankle instability after landing.

Effects of Static Hamstring Stretching on Maximal Sprint Speed and Relationship With Nordic Hamstring Strength.

This study aimed to determine the acute effects of static stretching of the hamstrings on maximal sprint speed and its spatiotemporal variables and lower-limb kinematics during the late swing phase, as well as the relationship with Nordic hamstring strength. The study had a within-participant experimental design. Sixteen healthy male college sprinters were asked to sprint 80m without static stretching and with static stretching of the hamstrings for 4 × 30s per leg before the sprint; both conditions were counterbalanced. The knee flexion peak torque was measured using the Nordic hamstring. The differences between no static stretching and static stretching as well as their relationship with Nordic hamstring strength were investigated. The results showed that the touchdown distance (p = .036) significantly increased following static stretching. Although not significant, maximal sprint speed decreased (p = .086), and the theoretical hamstring length (difference between knee angle and hip angle) at ipsilateral touchdown was greater (p = .069) following static stretching. In addition, a lower peak torque of the Nordic hamstring resulted in a more significant decrease in maximal sprint speed following static stretching. Therefore, static stretching of the hamstring just before sprinting may increase the theoretical hamstring length during the late swing phase at maximal sprint speed and induce kinematics that increases the hamstring strain injury risk. Moreover, it is suggested that improving the Nordic hamstring strength may help minimize the negative effects of static stretching on the hamstrings.

Radiological Differences Following Proximal Femoral Nail Antirotation (PFNA) Compared to the Contralateral Side and Its Correlation with Harris Hip Score (HHS) in Intertrochanteric Femoral Fracture After Three Months

Introduction: The incidence of intertrochanteric femoral fractures, which account for 50% of all hip fractures, is increasing as a result of the aging population. While PFNA surgery typically enhances outcomes, certain individuals continue to have pain, stiffness, and difficulties with their gait. This study aims to determine whether there is a correlation between post-surgical complications and changes in hip joint angles assessed three months following PFNA to lead future advances in PFNA surgery for older persons by comparing impacted and unaffected hips and correlating angles with patients' hip ratings. Methods: This study included 42 individuals who underwent surgery for intertrochanteric fractures aged 50 and above. Eligible participants must possess the ability to walk before to the study, have no history of previous leg fractures, and be capable of participating in rehabilitation. Individuals having comorbidities impacting these aspects or those unable to partake were not included. Result : This study looked at hip angles in 42 people who had surgery intertrochanteric fracture. While the participants varied in age and gender, the surgery itself didn't seem to significantly change the angles of their hip bones or their ability to walk. This suggests that PFNA may not directly affect hip mechanics on its own. Conclusion: This study indicates that attaining acceptable hip angles during the procedure could enhance patients' mobility and post-operative condition. Further investigation involving bigger cohorts and extended periods of observation is necessary to validate these findings and ascertain whether modifying these angles during surgery will result in improved outcomes following PFNA. Keywords: Intertrochanteric fracture; Hip fracture; PFNA

The impact of pediatric obesity on biomechanical differences across the gait cycle at three walking speeds

BackgroundObesity impacts a child's ability to walk with resulting biomechanical adaptations; however, existing research has not comprehensively compared differences across the gait cycle. We examined differences in lower extremity biomechanics across the gait cycle between children with and without obesity at three walking speeds. MethodsFull gait cycles of age-matched children with obesity (N = 10; BMI: 25.7 ± 4.2 kg/m2) and without obesity (N = 10; BMI: 17.0 ± 1.9 kg/m2) were analyzed at slow, normal, and fast walking speeds. Main and interaction effects of group and speed across hip, knee, and ankle joint angles and moments in sagittal, frontal, and transverse planes were analyzed using one-dimensional statistical parametric mapping. FindingsCompared to children without obesity, children with obesity had greater hip adduction during mid-stance, while also producing greater hip extensor moments during early stance phase, abductor moments throughout most of stance, and hip external rotator moments during late stance. Children with obesity recorded greater knee flexor, knee extensor and knee internal rotator moments during early stance, and knee external rotator moments in late stance than children without obesity; children with obesity also demonstrated greater ankle plantarflexor moments throughout mid and late stance. Interaction effects existed within joint kinetics data; children with obesity produced greater hip extensor moments at initial contact and toe-off when walking at fast compared to normal walking speed. InterpretationWhile few kinematic differences existed between the two groups, children with obesity exhibited greater moments at the hip, knee, and ankle during critical periods of controlling and stabilizing mass.

Lower Extremity Kinematic and Kinetic Characteristics as Effects on Running Economy of Recreational Runners.

This study aimed to determine associations between running economy (RE) and running sagittal plane kinematic and kinetic parameters. A total of 30 male recreational runners (age: 21.21 ± 1.22 yr, V̇O 2max : 54.61 ± 5.42 mL·kg -1 ·min -1 ) participated in two separate test sessions. In the first session, the participant's body composition and RE at 10 and 12 km·h -1 were measured. In the second session, measurements were taken for the sagittal plane of hip, knee, and ankle angles and range of motion (ROM), as well as ground reaction force. Moderate correlations were found between lower energy costs at 12 km·h -1 and smaller hip flexion at toe-off ( r = 0.373) as well as smaller peak hip flexion during stance ( r = 0.397). During the swing phase, lower energy costs at 10 km·h -1 were moderately correlated with smaller peak knee flexion and smaller knee flexion and extension ROM ( r = 0.366-0.443). Lower energy costs at 12 km·h -1 were moderately correlated with smaller peak hip and knee flexion as well as knee extension ROM ( r = 0.369-0.427). In terms of kinetics, there was a moderate correlation between higher energy costs at 10 km·h -1 and larger peak active force, as well as larger peak braking and propulsion force ( r = -0.470-0.488). Lower energy costs at 12 km·h -1 were moderately to largely correlated with smaller peak impact and braking force ( r = 0.486 and -0.500, respectively). Regarding the statistical parametric mapping analysis, most outcomes showed associations with RE at 10 km·h -1 , including knee flexion (42.5%-65.5% of the gait cycle), ankle plantarflexion (32.5%-36% of the gait cycle), active force (30.5%-35% of the stance phase), and propulsion force (68%-72.5% of the stance phase). Lower energy costs at 12 km·h -1 were correlated with smaller hip flexion (5.5%-12% and 66.5%-74%) and smaller knee flexion (57%-57.5%) during the running gait cycle. This study indicates that biomechanical factors are associated with RE in recreational runners. To design effective training methods to improve RE, coaches and runners should focus on the sagittal plane kinematics of the hip, knee, and ankle, as well as lower vertical and horizontal kinetic parameters.

Skiing economy and kinematic during a field double poling roller skiing among novice and experienced cross-country skiers

To assess the skiing economy (SE) and kinematics during double poling (DP) roller skiing between two groups of skiers in a field setting. Five experienced and five novice male skiers performed a SEDP test at 16 km∙h−1 on an outdoor athletics track. Gas exchange parameters were measured to determine SEDP. A two-dimensional video was filmed to measure the kinematics variables. Experienced skiers exhibited a 21% lower oxygen cost than novice skiers (p = 0.016) in DP, indicating a strong association between SEDP, cycle length and cycle rate (p < 0.001). Additionally, before the poling phase, experienced skiers manifested significantly greater maximum hip and knee extension angles than novice skiers (p < 0.001). During the poling phase, experienced skiers with a greater pole plant angle (p = 0.001), longer flexion time (p < 0.001) and higher flexion angular velocity in the elbow joint (p < 0.05) demonstrated better SEDP. There was an interaction effect of the one-repetition maximum bench press × group in SEDP (b = − 0.656, SE = 0.097, t = − 6.78, p = 0.001). Therefore, experienced skiers with better SEDP demonstrated more efficient cycles, potentially accomplished using dynamic full-body DP motion to ascertain effective propulsion. Combined upper body strength and ski-specific skill training may enhance SEDP in novice skiers.

Joint kinematics and SPM analysis of gait in children with and without Down syndrome

BackgroundIndividuals with Down syndrome (DS) walk with altered gait patterns compared to their typically developing (TD) peers. While walking at faster speeds and with external ankle load, preadolescents with DS demonstrate spatiotemporal and kinetic improvements. However, evidence of joint kinematic adjustments is unknown, which is imperative for targeted rehabilitation design. Research questionHow does increasing walking speed and adding ankle load affect the joint kinematics of children with and without DS during overground walking? MethodsIn this cross-sectional observational study, thirteen children with DS aged 7–11 years and thirteen age- and sex-matched TD children completed overground walking trials. There were two speed conditions: normal speed and fast speed (as fast as possible without running). There were two load conditions: no load and ankle load (2% of body mass added bilaterally above the ankle). A motion capture system was used to register the ankle, knee, and hip joint angles in the sagittal plane. Peak flexion/extension angles, range of motion, and timing of peak angles were identified. In addition, statistical parametric mapping (SPM) was conducted to evaluate the trajectory of the ankle, knee, and hip joint angles across the entire gait cycle. Results and significanceSPM analysis revealed the DS group walked with greater ankle, knee, and hip flexion compared to the TD group for most of the gait cycle, regardless of condition. Further, increasing walking speed led to improved ankle joint kinematics in both groups by shifting peak plantarflexion closer to toe-off. However, knee extension during stance was challenged in the DS group. Adding ankle load improved hip and knee kinematics in both groups but reduced peak plantarflexion around toe-off. The kinematic adjustments in the DS group suggest specific motor strategies to accommodate their neuromuscular deficits, which can provide a foundation to design targeted gait-based interventions for children with DS.