Hip Moments Research Articles

Test-retest reliability of kinematic and kinetic parameters during dual-task stair walking in the elderly.

Objective: This study aims to evaluate the test-retest reliability of kinematics and kinetics during single and dual-task stair walking in the elderly. Methods: Fifteen healthy elderly adults were recruited. Kinematic and kinetic parameters were measured using an infrared motion analysis system (Vicon, Oxford Metrics Ltd., Oxford, United Kingdom) and force platforms (Switzerland, Kistler 9287BA and 9281CA). Participants were tested under single-task and dual-task (serial 3 subtractions or carrying a cup of water) conditions. Each participant completed two sessions on two separate days with a 1-week interval. Intraclass correlation coefficients (ICC), Pearson correlation coefficient (r), and Bland-Altman plot were used to assess the reliability of stair walking. Results: When ascending stairs, the ICC of kinematics and kinetics ranged from fair to excellent (ICC = 0.500-0.979) in the single and dual tasks, except for step length (ICC = 0.394) in the single task. The r value of kinematics and kinetics ranged from 0.704 to 0.999. When descending stairs, the ICC of kinematics and kinetics ranged from good to excellent (ICC = 0.661-0.963), except for min hip moment (ICC = 0.133) and min ankle moment (ICC = 0.057) in the manual task. The r value of kinematics and kinetics ranged from 0.773 to 0.960 in the single and dual tasks. In the Bland-Altman plots, all the zero values and most of the dots fell in the 95% confidence interval, and the mean difference was found to be close to zero for all the parameters during stair walking. Conclusion: These results obtained from this study show the good test-retest reliability of step cadence, step speed, and step width during single- and dual-task stair walking in the elderly, and the poor reliability of step length during ascending stairs. All the kinetic parameters, including min hip moment, max knee moment, and min ankle moment, had good test-retest reliability during single- and dual-task stair walking, but min hip moment and min ankle moment had poor reliability during manual-task descending stair. These results may help researchers in the assessment of biomechanics of dual-task stair walking in the elderly and to interpret the effect of interventions in this population.

Allometric Scaling Hip Joint Moments Optimally Reduces Anthropometric Differences in Males and Females

ABSTRACT Running biomechanics are scaled to reduce the effects of anthropometric differences between participants. Ratio scaling has limitations, and allometric scaling has not been applied to hip joint moments. The aim was to compare raw, ratio and allometrically scaled hip joint moments. Sagittal and frontal plane moments of 84 males and 47 females were calculated while running at 4.0 m/s. Raw data were ratio scaled by body mass (BM), height (HT), leg length (LL) and BM multiplied by HT (BM*HT) and LL (BM*LL). Log-linear (for BM, HT and LL individually) or log-multilinear regression (BM*HT and BM*LL) exponents were calculated. Correlations and r 2 values assessed the effectiveness of each scaling method. Eighty-five per cent of raw moments were positively correlated to the anthropometrics with r 2 values of 10–19%. In ratio scaling, 26–43% were significantly correlated to the moments and a majority were negative, indicating overcorrections. The most effective scaling procedure was the allometric BM*HT, as the mean shared variance between the hip moment and anthropometrics was 0.1–0.2% across all sexes and moments and none had significant correlations. Allometric scaling of hip joint moments during running are advised if the goal is to remove the underlying effects of anthropometrics across male and female participants.

Effects of foot-ankle exercises on foot-ankle kinematics, plantar pressure, and gait kinetics in people with diabetic neuropathy: Secondary outcomes from a randomized controlled trial

BackgroundFollow-up report of secondary outcomes of a randomized, single-blinded, parallel controlled trial that investigated the benefits of a foot-ankle therapeutic exercise program on foot-ankle kinematics, plantar pressure, and lower limb kinetics during gait in individuals with diabetic neuropathy (DPN). MethodsSixty-six participants with DPN were randomly allocated into a control group (CG; n = 31), which received usual care, and an intervention group (IG; n = 35), which received usual care plus a 12-week group-based foot-ankle exercise program. Outcomes were assessed at baseline and 12 weeks by an assessor blinded to group allocation. ResultsThe generalized linear mixed model and intention-to-treat analysis revealed a greater hip extensor moment at push-off and greater hallux contact area in the IG than CG after 12 weeks. A within-group analysis revealed a larger arch height during stance and higher peak pressure and pressure-time integral at the central forefoot region in the IG after 12 weeks compared to baseline. There were no other significant group difference or changes over time in foot-ankle kinematics or in any other joint moment related to overall lower limb biomechanics. ConclusionThe increases in hip moment at push-off and hallux surface contact area suggest an improvement in the propulsion phase with greater participation of the toes in foot rollover after 12 weeks of a group-based foot-ankle exercises program for people with DPN. Individual face-to-face, longer-term, and more intensive interventions may be needed to positively influence foot-ankle biomechanics and pressure parameters in other plantar areas.

Hip width and metabolic energy expenditure of abductor muscles.

Despite a paucity of physiological evidence, simplistic biomechanical analyses have led researchers to assume that humans who have wider hips use more energy to walk. Pitting biomechanical first principles against physiological data has led to little deepening of our understanding of bipedalism and its evolution. Both approaches, however, use proxies for the energy used by muscles. We decided to approach the question directly. Using a musculoskeletal model of the human body that estimates the metabolic energy expenditure of muscle activation for 48 people (23 women), 752 trials were evaluated. Metabolic energy consumption for the abductor muscles was summed over a stride to create total abductor energy expenditure. We calculated the maximum hip joint moment acting in the coronal plane and the functional distance between the hip joint centers. We hypothesize that wider hips would be correlated with both maximum coronal plane hip moment and increased total abductor energy expenditure when mass and velocity were controlled. Linear regressions with multiple independent variables, clustered by participant to control for the non-independence of the data points, were performed in Stata. We found that hip width does not predict total abductor energy expenditure, although mass and velocity combine to predict 61% of the variation (both p<0.001). Maximum hip joint coronal plane moment is predicted by pelvic width (p<0.001) and, in combination with mass and velocity (both p<0.001), explains 79% of the variation. Our results indicate that people use their morphology in ways that limit differences in energy expenditure. Consistent with recent discussion, intraspecific variation might not be useful to understand differences among species.

Optimization of the Position and Stiffness of Passive Walking Assistance Devices

Walking is a fundamental movement in daily life; however, many factors affect walking that may reduce the mobility of the people. Walking assistance devices can help with gaining mobility back for people who suffer from walking problems. In the present study, a computational method to determine the location and stiffness of the assistive walking systems was developed. The human walking model was created by using nine rigid bodies and eight revolute joints connecting them in the sagittal plane. The walking assistance system was considered as a tension spring with both ends attached to the human walking model. A coordinate system was defined along the distal–proximal direction of the human body. The position of the walking assistance system was determined by using four design variables, and the optimal position of the assistive walking system to reduce the total positive joint energy was found around the hip joint at a walking speed of 1.3 m/s. Hip joint moment and power were significantly affected by the walking assistance system, and the total positive joint energy was reduced by 8.8%. Because walking speed significantly affects walking kinematics and kinetics, the effect of walking speed on the optimal walking assistance device was investigated. The position of the device was kept the same, and the optimal stiffness and free length of the spring were found at different walking speeds. Two different cases were considered: a speed-specific design in which stiffness characteristics were separately optimized for each speed and a general design in which stiffness characteristics were optimized by considering all walking speeds. It was found that, in both cases, hip joint moment and power significantly reduced, and the speed-specific design produced a slightly larger reduction in total joint energy. The performance of the walking assistance systems in both cases were found to be higher at faster walking speeds.

Equivalent system based inverse dynamics analysis of transfemoral prosthetic legs: Validation and application.

Inverse dynamics analysis of prosthetic legs with polycentric knees is complex due to increased number of links. The present work proposes a simple and general method called equivalent system (ES) analysis. The ES analysis provides forces and moment at hip joint as well as at the functional knee centre (FKC), the instant centre of the polycentric knee. The input to the ES analysis is the motion data. For validation of the proposed method, synthetic motion data for the swing phase of walking with prosthetic legs having different knees are generated by simulations using ADAMS. The hip kinetics evaluated by the proposed method is compared with that from ADAMS. The root mean square errors of the ES analysis are lower than 17 (10-6) N for hip reaction forces and 2.6 (10-6) Nm for the hip moments, thereby validating the proposed method. In order to demonstrate the application of the proposed methodology, the motion data of two transfemoral amputees using single-axis and four-bar knee prostheses are obtained during gait trials. The hip kinetics as well as kinetics at FKC are computed using ES analysis. Hip power during the swing phase is also evaluated and compared. The results are presented in this paper and discussed. The ES analysis is shown to be a versatile tool to provide insights into the human-mechanism interaction.

A Study on the Intersection of Ground Reaction Forces during Overground Walking in Down Syndrome: Effects of the Pathology and Left–Right Asymmetry

Motor dysfunctions in patients with Down Syndrome (DS) result in poor locomotion and an altered gait phenotype, characterized by compromised stability management and frequent bilateral asymmetries. Directing ground reaction forces to a point above the center of mass, referred to as the virtual pivot point (VPP), is one means of maintaining stability during walking. This cross-sectional observational study compared the dynamic gait function of 33 individuals with DS (mean age: 17.7 ± 6.4 years, 13 females) to a group of 36 healthy controls (mean age: 15.5 ± 6.1 years, 15 females), using the concept of the VPP. Results showed that the VPP was located more anteriorly in individuals with DS compared to healthy controls, with no differences in the variability (R2) or symmetry of VPP coordinates. This anterior VPP position is likely due to the larger hip moments observed in patients with DS during the propulsive phase of stance. High R2 values in DS suggest that the VPP is strongly related to dynamic stability during walking.

Hip joint function and reconstruction of the anterior femoral offset in patients with short stem vs. conventional THA

In cases where mobility and joint function are impaired after implantation of a THA, weakening of hip movement in both extension/flexion and adduction/abduction may play a role due to shortening of the physiological lever arm of the hip muscles. Mechanical factors of influence include the lateral femoral offset, which affects the lever arm, and the antetorsion angle of the hip prosthesis, which affects the anterior femoral offset. This study aimed to investigate the effect of an altered antetorsion angle of the implant on the hip moments and gait patterns of the patient. For this study, 13 patients with a conventional stem on one side and a calcar-guided short stem implanted on the contralateral side were included. To determine the maximum hip moment, tests were performed on a dynamometer in extension/flexion and adduction/abduction in addition to gait analysis. As a control, a comparison was made with data from a reference group of 30 healthy subjects. Both implants showed similar symmetry indices. There was a significant difference between the implants for adduction moments (p < 0.001). The ratios between the directions of moments showed no significant differences. The joint function measured by isokinetic measurements and gait analysis remains comparable to the healthy control group after short stem arthroplasty, but shows slight changes after conventional stem arthroplasty.

Changes in Joint Power and Energetics during a Sport-Specific Jumping Fatigue Protocol

Kinematic and kinetic changes in the lower extremities occur as an athlete becomes fatigued during vertical jumping; however, the specifics of these changes are not well-understood. Therefore, the purpose of this study was to quantify the influence of a sport-specific, vertical jumping fatigue protocol on the biomechanics of the ankle, knee, and hip joint. Twenty male varsity athletes performed repetitive standing countermovement squat jumps every 20 s until fatigued (vertical jump and reach height decreased to 88% of their maximum height for three consecutive jumps). The kinematics and kinetics of their lower extremities (ankle, knee, and hip) were quantified, and the ankle, knee, and hip joint’s moments, angular velocity, and joint power were compared. The participants performed an average of 175 jumps before they were classified as being fatigued. When they became fatigued, the peak power of the ankle and hip joints were substantially reduced due to a decrease in the angular velocity at both joints. Ankle and hip joint moments were unchanged. Peak power at the knee joint was also unchanged over the course of the jumping protocol. To maintain vertical jumping performance over the course of a game or to delay the influence of fatigue, training should be targeted at maintaining the angular velocity of the ankle and hip joints.

Multi-Joint Leg Moment Estimation During Walking Using Thigh or Shank Angles.

To reinstate human-like locomotion by using robotic prosthetics, orthotics or exoskeletons, a main challenge is how to coordinate the motion of these devices with that of the biological limbs. One approach to overcome this challenge is to identify firstly the relationships that exist between the kinematics and kinetics of the lower extremity joints and limbs. In this work we aimed to continuously estimate sagittal plane ankle, knee and hip moments using shank or thigh angles. For this purpose, neural network and wavelets were used in a nonlinear auto-regressive model with exogenous inputs. This approach circumvented the need for switching rules or intermediate parameters. To assess the performance of the estimator, four case studies were developed. First, thigh angles (inputs) were used to estimate hip moments (outputs). Second, thigh angles were used to estimate knee moments. Third, ankle moments were estimated using thigh angles, and in the fourth case study, ankle moments were estimated using shank angles. Three different databases involving 106 subjects at different walking speeds were used to evaluate estimation quality. The testing procedure involved both inter-subject and intra-subject evaluations. The best estimation performance was observed when ankle moments were estimated from shank angles. The weakest estimation performance was observed when knee moments were estimated using thigh angles at 0.5 m/s. For this case, the estimation quality was much better at 1.5 m/s. Average RMS errors were 0.13- 0.15, 0.10- 0.13, and 0.09- 0.12 [Nm/kg] for hip, knee and ankle moments, respectively. Average mean absolute errors MAEs were 0.10- 0.11, 0.07- 0.10, and 0.06- 0.08 [Nm/kg] for hip, knee and ankle moments, respectively. Average correlation coefficients were 0.90- 0.98 and 0.98- 0.99 for hip and ankle moment estimations. The value for knee was comparable only at high speed (0.96 for 1.5 m/s), while it was less accurate at slow speed (0.71 for 0.5 m/s). In general, for all of the joints, the estimation accuracy was comparable with that of other studies, although one source of input was employed (either shank or thigh angle).

Sensitivity of lower-limb joint mechanics to prosthetic forefoot stiffness with a variable stiffness foot in level-ground walking

This paper presents the effectsof the Variable Stiffness Foot (VSF) on lower-limb joint mechanics in level-ground walking. Persons with transtibial amputations use lower-limb prostheses to restore level-ground walking, and foot stiffness and geometry have been shown to be the main factors for evaluating foot prostheses. Previous studies have validated the semi-active and stiffness modulation capabilities of the VSF. The core aim of this study is to investigate the mechanical effects of adjusting stiffness on knee and ankle mechanics for prosthetic users wearing the VSF. For this study, seven human participants walked with three different stiffnesses (compliant, medium, stiff) of the VSF across two force plates in a motion capture lab. Linear mixed models were utilized to estimate the significance and coefficients of determinations for the regression of stiffness on several biomechanical metrics. A stiffer VSF led to decreased ankle dorsiflexion angle (p < 0.0001, r2 = 0.90), increased ankle plantarflexor moment (p = 0.016, r2 = 0.40), increased knee extension (p = 0.021, r2 = 0.37), increased knee flexor moment (p = 0.0007, r2 = 0.63), and decreased magnitudes of prosthetic energy storage (p < 0.0001, r2 = 0.90), energy return (p = 0.0003, r2 = 0.67), and power (p < 0.0001, r2 = 0.74). These results imply lower ankle, knee, and hip moments, and more ankle angle range of motion using a less stiff VSF, which may be advantageous to persons walking with lower-limb prostheses. Responsive modulation of the VSF stiffness, according to these findings, could help overcome gait deviations associated with different slopes, terrain characteristics, or footwear.

Effects of Core Stability Training on Kinematic and Kinetic Variables in Patients With Chronic Low Back Pain

Purpose: This study aims to assess the effects of an 8-week core stability training on the kinematics and kinetics of trunk flexion and extension motions in patients with chronic non-specific low back pain (CNSLBP). Methods: A total of 30 CNSLBP patients with the age range of 25 to 45 years were randomly divided into 2 equally sized groups. The subjects were identified through clinical examination. Before and after the training, tests were applied to assess peak 3-dimensional hip joint moments, peak negative and positive hip joint powers, and lumbopelvic coupling angles during trunk flexion and extension motions. The first group underwent an 8-week core stability training program, including the specific exercise of the deep muscles of abdominal along with the lumbar multifidus co-activation. After the 8-week program, the post-test stage was performed similarly to the pre-test. Results: The main effects of “time” (P=0.029, f=0.84) and “time-by-group” interactions (P=0.03, f=0.16) for hip abductor moments and internal rotator moment (P=0.03, f=0.87) were significant. A trend toward the statistically significant main effect of “time” was found for the coupling angle during the flexion phase (P&lt;0.05, f=1.88), extension phase (P=0.02, f=0.93), and “time×group” interaction during the flexion (P&lt;0.05, f=1.96), extension (P=0.01, f=0.96) phases. Conclusion: Core stability training has the potential to improve kinematics and kinetics during trunk flexion and extension motions in patients with CNSLBP.

Gait analysis after total hip arthroplasty by direct minimally invasive anterolateral approach: A controlled study

IntroductionClinical and functional improvement after minimally invasive total hip arthroplasty (THA) has become increasingly controversial. The minimally invasive anterolateral approach (MIALA) allows rapid recovery resulting in a reduced need for rehabilitation. Alterations in muscle and static balance have previously been demonstrated. Results in the context of quantified gait analysis (QGA) and MIALA compared to an asymptomatic population remain unknown beyond one year postoperatively. Thus, the main objective of this controlled study was to compare the spatiotemporal parameters of gait, obtained using a QGA, beyond one year postoperatively in subjects operated on for THA by MIALA, with a group of asymptomatic subjects of the same age. The secondary objectives of the study were to compare the other QGA and EMG data acquired in operated subjects with asymptomatic subjects. HypothesisWe hypothesized that QGA and EMG parameters would not normalize beyond one year postoperatively. Patients and methodsThirty-one subjects were recruited, including 16 patients (68 years old; IQR: 65–70) who underwent MIALA, at 15.5 months postoperatively (IQR: 13–17) and 15 asymptomatic subjects (62 years old; IQR: 61–71). Subjects underwent QGA and maximal isometric muscle force tests on the gluteus medius, gluteus maximus, Tensor Fascia Lata (TFL) and Sartorius muscles. Spatiotemporal gait parameters were the primary endpoint. The other QGA parameters: kinetics (characteristic values of vertical ground reaction forces, peak hip moments) and kinematics (hip joint amplitudes and pelvic mobility in the frontal and sagittal plane) constituted the secondary criteria. ResultsFive subjects were excluded for unrestored offset. Walking speed was lower in operated patients (1.03m/s versus 1.18m/s, p=0.005). Maximal isometric muscle force moments were lower in patients operated on for the gluteus maximus and medius as well as the TFL (p<0.005). The vertical ground reaction forces were lower for the operated patients for the loading phase (FzFCmax, p=0.001), the single stance phase (FzSPmin, p=5.05.10−2) and the swing phase (FzTOmax, p=0.0002). The moments were lower in the sagittal plane for the operated patients (0.6N.m for the operated versus 1.1N.m for the asymptomatic, p=0.02). The pelvic amplitudes in the sagittal plane were lower for operated patients (3.3° versus 7.2°, p=0.05). DiscussionOur hypothesis appears to be validated. Gait deficits persisted beyond one year postoperatively after THA with MIALA. A decrease in walking speed, maximal isometric muscle force of the gluteus medius and gluteus maximus and TFL was observed, as well as a decrease in propulsive force and peak hip moment. Functionally, these results could signify muscle damage following surgery, requiring rehabilitation for improved muscle function. Level of proofIII: Non-randomized controlled trial.

The functional role of hip muscles during gait in patients with increased femoral anteversion

BackgroundFemoral anteversion affects the lever arm and moment-generating capacity of the hip abductors, while an increased hip internal rotation during walking was proposed to be a compensatory mechanism to restore the abductive lever arm. Children with isolated increased femoral anteversion, however, do not always present a deficit in the net hip abduction moment during gait, suggesting that a more comprehensive understanding of the effect of morphology and motion on muscle forces and moments is needed to aid clinical decision making. Research questionAre muscle contributions to hip joint moments and muscle forces altered in patients with increased femoral anteversion and internally rotated gait pattern compared to a control group of typically developing children? And how would the functional role of the muscle be altered if the patients walked straight? MethodsThis follow-up study compared patients with increased femoral anteversion (n = 42, 12.8 ± 1.9 years, femoral anteversion: 39.6 ± 6.9°) to controls (n = 9, 12.0 ± 3.0 years, femoral anteversion: 18.7 ± 4.1°). Muscle forces and moment contributions were calculated using personalized musculoskeletal models. Additionally, a hypothetical scenario, in which the gait of the controls was modelled with an anteverted femoral morphology, was used to understand what would happen if the patients walked straight. ResultsGluteus medius abductive contribution was lower in patients compared to controls, despite a comparable net abduction moment around the hip. Patients presented lower muscle forces. However, if modelled to walk straight, they would require higher forces as well as a larger co-contraction of both hip internal and external rotators in the transversal plane. SignificanceThis study suggests that patients with increased femoral anteversion walking with an internally rotated gait pattern present lower muscle forces, but when modelled to walk straight muscle forces increase. The current results provide important information to better understand this condition and improve treatment recommendations in these patients.

Greater Hip Moments in Rear-Foot-Elevated Split Squats Than in Conventional Back Squats With the Same Relative Intensity of Loads.

Arakawa, H, Mori, M, and Tanimoto, M. Greater hip moments in rear-foot-elevated split squats than in conventional back squats with the same relative intensity of loads. J Strength Cond Res 37(5): 1009-1016, 2023-Rear-foot-elevated split squat (RFESS) is often performed as an alternative to conventional double-leg back squat (DLBS). This study aimed to compare 3-dimensional joint kinetics of DLBS and RFESS using the same relative intensity of loads. Eight male college rugby players performed 3 repetitions of DLBS and RFESS at 10-repetition-maximum (RM) loading. Before testing, both exercises were incorporated into the subjects' training program with a progressive increase in loads for 4 months. A 3-dimensional optical motion capture system and force platform were used for data collection. The 3-dimensional moments at the knee and hip joints in each of the 3 axes were calculated based on the inverse dynamic procedure. p values < 0.05 were considered statistically significant. The hip extension moment was 44% greater in the RFESS than in the DLBS at the bottom position ( p < 0.01) and 47% greater for the peak value ( p < 0.01) on harmonic averages. The hip abduction and external rotation moments at the bottom position were also greater in the RFESS than in the DLBS. The findings suggest that the magnitude of hip extension moment per leg in DLBS tends to be restricted to less than that expected from the given strength level. In conclusion, the mechanical contribution of hip extensors per leg can be greater in RFESS than in DLBS when using respective 10RM loads, even if the absolute load is smaller and the trunk is more upright in RFESS.

Running Mechanics After Repeated Sprints in Femoroacetabular Impingement Syndrome, Cam Morphology, and Controls.

People with femoroacetabular with femoroacetabular impingement syndrome (FAIS) often report pain during sports involving repeated sprinting. It remains unclear how sports participation influences running biomechanics in individuals with FAIS. Changes in running biomechanics and/or isometric hip strength after repeated sprint exercise would be greatest in individuals with FAIS compared with asymptomatic individuals with (CAM) and without cam morphology (Control). Controlled laboratory study. Level 3. Three-dimensional hip biomechanics during maximal running (10 m) and hip strength were measured in 49 recreationally active individuals (FAIS = 15; CAM = 16; Control = 18) before and after repeated sprint exercise performed on a nonmotorized treadmill (8-16 × 30 m). Effects of group and time were assessed for biomechanics and strength variables with repeated-measures analyses of variance. Relationships between hip pain (Copenhagen Hip and Groin Outcome Score) and changes in hip moments and strength after repeated sprint exercise were determined using Spearman's correlation coefficients (ρ). Running speed, hip flexion angles, hip flexion and extension moments, and hip strength in all muscle groups were significantly reduced from pre to post. No significant between-group differences were observed before or after repeated sprint exercise. No significant relationships (ρ = 0.04-0.30) were observed between hip pain and changes in hip moments or strength in the FAIS group. Changes in running biomechanics and strength after repeated sprint exercise did not differ between participants with FAIS and asymptomatic participants with and without cam morphology. Self-reported pain did not appear to influence biomechanics during running or strength after repeated sprint exercise in participants with FAIS. A short bout of repeated sprinting may not elicit changes in running biomechanics in FAIS beyond what occurs in those without symptoms. Longer duration activities or activities requiring greater hip flexion angles may better provoke pathology-related changes in running biomechanics in people with FAIS.

Individuals with Bilateral Cerebral Palsy Rely On Excessive Hip Extension To Complete A Step-Up Task

<h3>Research Objectives</h3> To investigate the hip, knee, and ankle joint moments of individuals with bilateral cerebral palsy (CP) during a step-up task. Due to distal joint impairment, we hypothesized that individuals with bilateral CP would generate less knee and ankle moments and more hip moments when stepping up than individuals without CP. <h3>Design</h3> In this cross-sectional study, participants were instructed to step up onto a 10.2-cm platform 5-15 times with the same leading limb. <h3>Setting</h3> University gait laboratory. <h3>Participants</h3> We recruited from convenience samples of individuals with and without bilateral CP between 5-19 years of age. Individuals without bilateral CP (n=11, 6 females, mean age=12.8 years) were included if they had no known neurological conditions. Individuals with bilateral CP (n=5, 1 female, mean age=10.6 years) were included if they had some ambulatory function without assistive devices or orthotics, no botulinum toxin injections in the past 6 months, no lower limb surgeries in the past year, and no serious co-morbidities. <h3>Interventions</h3> N/A. <h3>Main Outcome Measures</h3> Extensor support moments were calculated by summing normalized hip, knee, and ankle sagittal plane moments. Peak support moments were identified in the push-off and pull-up stance phases, where typically the ankle and knee joints generate the highest moments, respectively. Individual joint contributions to peak support moments were averaged and compared between groups using a Welch's t-test. <h3>Results</h3> For the push-off phase, the difference in hip extension moments was significant between groups, where individuals with bilateral CP generated larger hip moments during peak support moments compared to individuals without bilateral CP (p< 0.001, CI: [0.445 0.798] Nm/kg). For the pull-up phase, differences in hip and knee extension moments were significant between groups. Individuals with bilateral CP generated larger hip moments (p< 0.001, CI: [0.364 0.911] Nm/kg) and smaller knee moments (p=0.007, CI: [-0.729 -0.161] Nm/kg) during peak support moments compared to individuals without bilateral CP. <h3>Conclusions</h3> Increased generation of hip extension moments during a step-up task is likely a neural and biomechanical compensation for distal joint impairment in individuals with bilateral CP. <h3>Author(s) Disclosures</h3> None.

Potentiation of Stretch Shortening Cycle of Hip Moment and Power Only predict Jump Performance Enhancement

<h3>Research Objectives</h3> To investigate if lower-extremity joint specific potentiation of stretch shortening cycle (SSC) during the propulsive phase of jump test predicts jump height. <h3>Design</h3> Cross-sectional study. <h3>Setting</h3> University research laboratory. <h3>Participants</h3> Twenty-two young adults (12 females; mean age=25.75±3.03 years). <h3>Interventions</h3> Not applicable. <h3>Main Outcome Measures</h3> Participantsperformed three countermovement jump (CMJ) and static Jump (SJ) and bent their knees to the same flexion degree on two floor-embedded force platforms (AMTI). Using a 3-dimensional (3D) motion capture system (Vicon), jump height (JH) was measured using greater trochanters markers data of both lower extremities. Joint-based moment (Jmom) and power (Jpwr) of hip, knee, and ankle were calculated. Potentiation of SSC was calculated as CMJ/SJ ratios of JH, Jmom, and Jpwr for hip, knee, and ankle. The Vicon system contains 11 infrared cameras and two force platforms to synchronize kinetic and kinematic data. Linear regression models were used to examine if SSC potentiation predicts JH, controlling for knee joint angle and sex. <h3>Results</h3> JHPotentiation was 1.30±0.24. SSC Jmom potentiation was 1.33±0.40, 1.04±0.13, and 1.02±0.12 for hip, knee, and ankle, respectively. SSC Jpwr Potentiation was 1.39±0.53, 1.03±0.18, and 1.02±0.18 for hip, knee, and ankle, respectively. The regression models documented that SSC potentiation of hip Jpwr and Jmom predicted 77% and 87% of the variance in JH, respectively, after controlling for knee joint angle and sex. No other significant JH predictors were identified (p>0.05). <h3>Conclusions</h3> The findings show that hip Jmom and Jpwr SSC potentiation were associated with Jump test performance during the propulsive phase These findings provide an insight into understanding the mechanical function of the contribution of SSC potentiation of the lower extremities to jump tests performance. <h3>Author(s) Disclosures</h3> All authors declare no conflicts.

Properties of the iliotibial band and their relationships with gait parameters among patients with knee osteoarthritis.

This study aimed to determine the thickness and stiffness of the iliotibial band(ITB) in patients with knee osteoarthritis (KOA) and to identify the gait parameters that are associated with ITB properties. Eighteen female patients with radiographically diagnosed medial KOA and knee pain (age: 69.7 ± 5.9 years, body mass index: 23.0 ± 3.1 kg/m2 ) and 22 age-matched female individuals without knee pain (age: 69.1 ± 7.0 years, body mass index: 21.6 ± 3.6 kg/m2 ) were included. Shear wave elastography images were obtained at the height of the proximal pole of the patella with the participants in the supine position, and the ITB thickness and shear wave velocity, which is a surrogate measure of stiffness, were calculated. In patients with KOA, the knee and hip joint angles and moments during walking were calculated using a motion analysis system. The shear wave velocity was significantly higher in patients with KOA than in asymptomatic adults (11.3 ± 1.0 vs. 10.0 ± 1.8 m/s, respectively; p = 0.010); however, the thickness did not differ between them (2.1 ± 0.3 vs. 2.0 ± 0.3 mm, respectively; p = 0.705). The time-integral value of the knee adduction moment (β = 0.507, p = 0.032) and maximum value of the hip flexion moment (β = 0.498, p = 0.036) were associated with the shear wave velocity. Meanwhile, no parameters were associated with the thickness. The ITB was stiffer in patients with KOA than in asymptomatic adults; such a stiffer ITB was associated with greater knee adduction and hip flexion moments during walking. Clinical Significance: Greater mechanical loading was associated with a stifferITBin patients with KOA.

A two-stage disto-proximal braking modality to interrupt gait initiation in healthy adults

The purpose of this investigation was to determine the effect of unexpected gait termination in able-bodied participants during gait initiation on spatiotemporal and stance limb biomechanical parameters.Twenty-one healthy adults took part in this study and were divided into two groups based on the natural anterior or posterior incline of their trunk. Each participant performed 15 random trials of gait initiation: 10 trials with a Go signal and 5 with Go-&-Stop signals. Spatiotemporal parameters were assessed between the Go signal and the first heel contact. Ankle, knee, and hip joint moments were calculated in the sagittal plane. Free moment and impulse were also calculated for the stance limb.Spatiotemporal parameters were not influenced by the mean trunk inclination (p > 0.05), but participants with a forwardly-inclined trunk presented higher hip extension moments (p < 0.05). Unexpected stopping required smaller ankle and knee moments compared to the Go condition (p < 0.05). The hip extension moments appeared to be independent of gait initiation conditions (p > 0.05). The capacity of able-bodied people to interrupt their gait initiation relied on a two-stage disto-proximal braking modality involving explosive motor patterns at the ankle and hip joints.Such a pattern could be altered in vulnerable people, and further studies are needed to investigate this. This study determined a clinical method applicable as a functional protocol to assess and improve the postural control of people suffering from a lack of motor modulation during crucial transient tasks. Such tasks are essential in activities of daily living.