Hip Angles Research Articles

Innovative hip-knee health evaluation: Leveraging pose estimation for single-leg stance postural stability assessment

The analysis of the Hip and Knee (HK) joint angles during single-leg stance (SLS) activity contributes to a great understanding of the bio-mechanical mechanisms and balance maintenance across different age groups. Comprehending how these joints operate in the dynamic state is critical for identifying age-related changes in joint control and stability which can contribute to reducing the risk of falls and improving mobility among people. The possibility of revealing the health of HK joints without resorting to an MRI scan is the significance of this work. By obtaining the data on joint angles during the SLS test, we succeeded in identifying those with a higher risk of HK issues and thus the possibility of early intervention and treatment. Our proposed work is going to use a pose estimation technique that will track the trajectories of HK angles followed by association with instabilities or compromised balance in this way, we can detect the affected joint and evaluate the severity of the issue. The study found stable mean and standard deviation values for HK joints in a young participant, both hips (107.14 ± 5, 96.42 ± 7) and both knees (36.76 ± 7, 44.30 ± 4), these values align with the expected norm (110–120° for the hip and 45–65° for the knee) which indicates stable results. while elderly participants showed high variability and low mean values for both hips (65.42 ± 77, 85 ± 76.67) and both knees (4.15 ± 10.8, 7 ± 18) indicating concerns about joint health and stability. The evaluation of HK joint angles through SLS activity offers new insights.

Impact of various training programs on lower limb biomechanics in adolescent Latin dancers

Latin dance attracts many young dancers globally. While these adolescents exhibit flexibility and imitation skills, their muscular strength and neuromuscular control often fall short, making complex movements challenging. Thus, incorporating functional training methods is essential for enhancing performance and reducing injury risk. This study, a total of 30 adolescent female Latin dancers aged 12–14 years with at least one year of training and competition experience were recruited for this study and randomly divided into two groups: One group of 15 students (average height 154.37 ± 3.82 cm, average weight 45.31 ± 5.29 kg) received traditional Latin dance training, and the other group of 15 students (15 students average height 154.73 ± 4.28 cm, average weight 44.63 ± 4.37 kg) received traditional Latin dance training and based on traditional Latin dance training, functional exercise was carried out for 12 weeks. A Vicon motion capture system, force platform, and electromyography were used to collect biomechanical data. Paired samples t-tests assessed significant differences between groups pre- and post-intervention. The experimental group showed significant improvements post-intervention: in the sagittal plane, ankle joint angles improved by 14.01% to 52.21% (p < 0.001); in the coronal plane, knee joint angles increased by 0% to 31.21% (p < 0.001) and 66.67% to 100% (p < 0.001); in the horizontal plane, hip joint angles improved by 4.99% to 76.00% (p < 0.001). Muscle activation showed significant increases in gastrocnemius lateral (p = 0.016), gluteus maximus (p = 0.001), tibialis anterior (p = 0.014), and rectus femoris (p < 0.001). Functional training enhances joint flexibility, muscle activation, balance, and overall performance in adolescent Latin dancers. Integrating functional training into regular routines can improve athletic performance and lower injury risk, informing the development of targeted training programs.

Validation of a 3D Markerless Motion Capture Tool Using Multiple Pose and Depth Estimations for Quantitative Gait Analysis

Gait analysis is essential for evaluating walking patterns and identifying functional limitations. Traditional marker-based motion capture tools are costly, time-consuming, and require skilled operators. This study evaluated a 3D Marker-less Motion Capture (3D MMC) system using pose and depth estimations with the gold-standard Motion Capture (MOCAP) system for measuring hip and knee joint angles during gait at three speeds (0.7, 1.0, 1.3 m/s). Fifteen healthy participants performed gait tasks which were captured by both systems. The 3D MMC system demonstrated good accuracy (LCC > 0.96) and excellent inter-session reliability (RMSE < 3°). However, moderate-to-high accuracy with constant biases was observed during specific gait events, due to differences in sample rates and kinematic methods. Limitations include the use of only healthy participants and limited key points in the pose estimation model. The 3D MMC system shows potential as a reliable tool for gait analysis, offering enhanced usability for clinical and research applications.

Performance of Artificial Neural Network Compared to Multi-Linear Regression in Prediction of Countermovement Jump Height

Previous research has used primarily linear regression models to predict jump height and establish contributors of performance. The purpose of this study was to compare the performance of artificial neural network (ANN) and multi-linear regression (MLR) in prediction of countermovement jump (CMJ) height and investigating the contribution of kinematic variables to CMJ performance. Thirty-four healthy young male athletes performed a total of 204 CMJ while eight kinematic variables (the hip, knee, and ankle angles at the begging of the concentric phase of CMJ, the hip and knee take-off angles, and the shoulder, hip, and knee maximum angular velocities) were used as inputs to ANN and MLR to predict CMJ height. The correlation coefficients between the jump height and the predicted value by the developed models indicated that ANN predict CMJ height better than MLR (R2 = 0.68 compared to R2 = 0.44). Moreover, the root mean squared error of prediction showed better performance of the ANN rather than the MLR (4.8 cm compared to 5.3 cm). The shoulder and hip maximum angular velocities were the most important contributors, and then the hip and knee take-off angles contributed to CMJ height. In conclusion, implementing ANN to identify key variables of performance may also be relevant for other sport skills.

The Kinetic and Kinematic Efficacy of Posterior Leaf Spring Ankle-foot Orthosis in Patients with Drop foot

Background: Dorsi flexor weakness is one of the common consequences of stroke with a negative impact on normal walking. Posterior leaf spring (PLS) Ankle Foot Orthosis (AFO) is the most frequent prescription to assist foot clearance and leg propulsion in these patients. However, the real efficacy of this AFO needs more attention. This study aimed to investigate the efficacy of PLS AFO on gait outcomes as the most common AFO in drop foot post-stroke patients. Methods: The study design was a pre–post-test experiments in which twenty drop foot patients with a mean age of 65 years with a mean age of 58.45 (±5.23) years who were 4/5 years post-stroke. They walked at self-selected walking speed on a 10 meters walk away in two conditions of with their own shoes and PLS AFO. The 3D motion capture gait analysis system including 6 vicon cameras and a Kistler force plate were used in order to measure gait kinetic and kinematic variables. For each trial, each joints (ankle, knee and hip) angle, moment and power were averaged over one-minute walking. Results: Walking with PLS showed a statistically significant improve kinetic and kinematic variables in hip, knee and ankle joints included power, moments and angles at entire gait cycle. P<0.05. Conclusions: In our study of stroke patients who were fitted with a PLS AFO, immediate significant improvements occurred in most kinetic and kinematic than shoes only in sacrifice some others.

Establishing the Reliability of the GaitON® Motion Analysis System: A Foundational Study for Gait and Posture Analysis in a Healthy Population

Background: Gait and posture analysis plays a crucial role in understanding human movement, with significant applications in rehabilitation, sports science, and clinical settings. The GaitON® system, a 2D motion analysis tool, provides an accessible and cost-effective method for assessing gait and posture. However, its reliability in clinical practice, particularly for intra-rater consistency, remains to be evaluated. This study aims to assess the intra-rater reliability of the GaitON® system in a healthy population, focusing on gait and posture parameters. Methods: A total of 20 healthy participants (10 males and 10 females) aged 18 to 50 years were recruited for the study. Each participant underwent gait and posture assessments using the GaitON® system on two separate occasions, spaced one week apart. Video recordings from anterior and posterior views were used to analyze gait, while images from anterior, posterior, and lateral views were captured to assess posture with markers placed on key anatomical landmarks. The reliability of the measurements was analyzed using intraclass correlation coefficients (ICC), a standard error of measurement (SEM), and the smallest detectable difference (SDD) method. Results: The GaitON® system demonstrated excellent intra-rater reliability across a wide range of gait and posture parameters. ICC values for gait parameters, including hip, knee, and ankle joint angles, ranged from 0.90 to 0.979, indicating strong consistency in repeated measurements. Similarly, ICC values for posture parameters, such as the head alignment, shoulder position, and ASIS alignment, were above 0.90, reflecting excellent reliability. SEM values were low across all parameters, with the smallest SEM recorded for the hip joint angle (0.37°), and SDD values further confirmed the precision of the system. Conclusion: The GaitON® system provides reliable and consistent measurements for both gait and posture analysis in healthy individuals. Its high intra-rater reliability and low measurement error make it a promising tool for clinical and sports applications. Further research is needed to validate its use in clinical populations and compare its performance to more complex 3D motion analysis systems.

Lower limbs kinematic analysis during a jump landing task in soccer players with unilateral anterior cruciate ligament reconstruction

BackgroundFatigue leads to an acute decline in muscle strength, altered patterns of lower extremity muscle activation, changes in hip and knee kinematics. In terms of the effects of fatigue on knee joint kinematics during plyometric training, there is still a lack of knowledge regarding kinematic differences between athletes who passed the ACL reconstructions rehabilitation period and healthy athletes. Therefore, this study aimed to compare lower limb joint kinematic parameters between reconstructed cruciate ligament and healthy control soccer players during jump landing in a fatigued setting.MethodsLower limb kinematic parameters were recorded in 20 professional soccer players (age, 24.95 ± 2.92 years; body mass, 77.20 ± 12.88 kg; height, 1.77 ± 3.19 m) during jump landing task before and after the fatigue protocol. The control group consisted of healthy subjects and the experimental group consisted of subjects with ACL reconstruction by thigh transplantation. Kinematic data was recorded with 4 cameras to measure lower limb angles at first foot contact and maximum range of motion.ResultsThe results showed that before fatigue, there was only a significant difference between the two groups in the maximum range of motion of the non-involved hip joint (P = 0.022) and angle of the involved hip at first contact (P = 0.049). In other data on joint range of motion or initial contact angle, no significant difference was observed between the two groups (P > 0.05). After fatigue protocol, there was a significant difference in initial foot contact in non-involved (P = 0.030), and involved (P = 0.020) hip joint angles between the two groups. However, no significant difference in initial contact angle or range of motion of other joints was observed between the groups.ConclusionsThis study shows that plyometric fatigue does not contribute to numerous changes in contact angles and range of motion in lower extremity joints in healthy soccer players and those with a history of cruciate ligament repairs.

Run-up velocity and jumping ground reaction force of Chinese female gymnasts

The run-up velocity and jumping ground reaction force directly influence gymnasts’ ability to perform more difficult manoeuvres and win competitions on vault. However, the variables influencing them among elite female gymnasts remain inadequately understood and warrant detailed investigation. This study aimed to analyse critical variables including run-up velocity and jumping ground reaction force, and to compare these factors across different vault types while further exploring the correlations among them. The study hypothesized that there are significant differences in run-up velocity and jumping ground reaction force across vaulting types, and that these differences will affect athletes’ performance. To test this hypothesis, the study analyzed data from performance tests on 16 elite Chinese female gymnasts, focusing on vaulting run-up velocity and jumping ground reaction force. Descriptive statistics were used to summarize the data, and binary logistic regression analysis was employed to investigate the relationships between the variables. The study found significant differences in interval run-up velocities between the Front handspring vaults and the Tsukahara vaults, particularly before the last 10 m (p = 0.04) and the last 5 m (p = 0.03). Specifically, the Front handspring vaults had higher velocities before the last 10 m, while the Tsukahara vaults had higher velocities within the last 5 m. Differences were also noted in the lengths of the penultimate (p = 0.03), last (p = 0.01), and hurdle steps (p = 0.04). The jumping ground reaction force showed a strong negative correlation with run-up velocity before the last 10 m (ρ = -0.469, p < 0.01) and the last 5 m (ρ = − 0.604, p < 0.01). However, no significant associations were found with the 25 m run-up velocity (p = 0.346). Significant differences were observed in the hip joint angle (p = 0.001) and the trunk-to-ground angle (p = 0.001), but not in the landing angle (p = 0.435) and take-off angle (p = 0.594) during the take-off phase. These findings suggest that revising the run-up rhythm and improving pedaling techniques could contribute to the successful performance of more difficult vaulting maneuvers for female elite gymnasts in China.

Effects of Mild Fatigue on Biomechanics of Single Leg Landing in Young Male Volleyball Players

Objective: To investigate the effects of mild fatigue on the biomechanics of the lower limbs of young male volleyball players while performing single leg landing tasks. Methods: A total of ten young male volleyball players were recruited as participants in this study. After the single leg landing was performed, we compared the performance between those with and without fatigue (post- and non-fatigue, respectively). Kinematics and kinetics were collected using instruments, and related captured data were imported into OpenSim to analyze the hip, knee, and ankle joints. Results: We found that the ankle dorsiflexion angle at initial contact was significantly decreased in the post-fatigue group compared to the non-fatigue one. Meanwhile, the peak gluteus maximus force, peak gluteus medius force, peak tibialis posterior force, and peak gastrocnemius force significantly increased. There were no significant differences in the hip and knee joint flexion angles as well as the quadriceps and biceps femoris long head forces between the two groups. Conclusions: Mild fatigue can affect the performance of single leg landing, and players need to control the lower limbs by generating a higher muscle force to cope with the instability induced by fatigue. In a fatigued state, following initial contact with the ground, a decreased ankle dorsiflexion angle necessitates an increase in gastrocnemius and tibialis posterior muscle force to maintain stance during landing.

Impact of Quadriceps Muscle Fatigue on Ankle Joint Compensation Strategies During Single-Leg Vertical Jump Landing.

This study investigates the impact of quadriceps fatigue on lower limb biomechanics during the landing phase of a single-leg vertical jump (SLJ) in 25 amateur male basketball players from Ningbo University. Fatigue was induced through single-leg knee flexion and extension exercises until task failure. Kinematic and dynamic data were collected pre-fatigue (PRF) and post-fatigue (POF) using the Vicon motion capture system and the AMTI force platform and analyzed using an OpenSim musculoskeletal model. Paired sample t-tests revealed significant changes in knee and hip biomechanics under different fatigue conditions, with knee joint angle (p < 0.001), velocity (p = 0.006), moment (p = 0.006), and power (p = 0.036) showing significant alterations. Hip joint angle (p = 0.002), moment (p = 0.033), and power (p < 0.001) also exhibited significant changes. Muscle activation and joint power were significantly higher in the POF condition, while joint stiffness was lower. These findings suggest that quadriceps fatigue leads to biomechanical adjustments in the knee and hip joints, which may increase the risk of injury despite aiding in landing stability.

Biomechanical Analysis of the “Cuban Motion”

Abstract Purpose “Cuban Motion” (CM) is a term often used to label a basic movement of many Latin-American dances, such as salsa and bachata. It is characterized by a cyclical and rhythmic flexion and rotation of the pelvis, accompanied by ample movements of the spine and lower limbs. Since Latin dances are considered both a recreational activity and a kind of healthy gymnastics for young and older subjects, a biomechanical analysis of the CM was performed to quantitatively assess the main features of this movement, from joint kinematics to muscle activations. Method The study combined experimental acquisitions with a Vicon Motion Capture system and musculoskeletal analyses in OpenSim. Only one subject was considered, an instructor of Latin dances, who was equipped with 55 retro-reflective markers, according to the Full Body CGM2.5 marker set. Data were processed in OpenSim, using the ThoracoLumbar model (111 DoFs and 620 musculo-tendon actuators). Results The cycle of the CM and its main events were defined. Results showed a wide RoM of many joints, with correlations between hip and knee flexion angles and among list, between hip adduction and shoulder flexion. The main role of the iliopsoas and the ileus costalis muscles was observed. Conclusions The current study quantified the CM as a physical exercise using a biomechanical approach similar to a gait analysis. The main kinematic and kinetic features were described, also providing an estimation of the muscle activations and joint reactions, derived from simulation activity in OpenSim. The main limitation of this study is the focus on a single subject, but this step was necessary to define a context and guidelines for future investigations, where we are going to compare èlite vs. novices and male vs. female dancers.

Analysis of the mechanical characteristics of progressive one-handed underhand shooting in basketball play through kinematics

Background: Progressive one-handed underhand shooting is not only a key movement in basketball but also a primary method of scoring. Objective: This paper aims to compare the mechanical characteristics of players at different levels while performing the progressive one-handed underhand shooting movement to guide training. Methods: Ten athletes were divided into an excellent group and an ordinary group. The shooting was conducted using two SONY cameras, and the kinematics data were acquired through re-analysis in the Simi 3D Motion system for comparative analysis. Results: The average number of successful shots per person in the excellent group was 8.12 ± 0.81, which was significantly different from the ordinary group. During ball holding, the first step length of the excellent group was 1.91 ± 0.03 m, showing a significant difference compared to the ordinary group. At the beginning of ball holding, the right elbow joint angle for the excellent group was 121.26° ± 0.58° and the right hip joint angle was 135.64° ± 0.78°, both significantly different from those in the ordinary group. At the end of holding the ball, the excellent group had a right shoulder joint angle of 51.26° ± 2.36° and a right elbow joint angle of 70.34° ± 1.68°, which was significantly different from the ordinary group. At the end of jump, the excellent group had a right shoulder joint angle of 80.16° ± 2.21° and a right elbow joint angle of 87.45° ± 1.68°, which was significantly different from the ordinary group. During the shooting phase, the excellent group had a shooting angle of 60.12° ± 2.36°, a shooting height of 2.92 ± 0.03 m, and a shooting speed of 4.12 ± 0.46 m/s, all showing significant differences compared to the ordinary group. Conclusion: The excellent group with more sufficient stride, push, and extension and better shooting parameters performed better in performing the movement of progressive one-handed underhand shooting.

Correlation between the biomechanical characteristics and stability of the 143D movement during the balance phase in competitive Tai Chi.

To explore the biomechanical factors affecting the stability of athletes in the 143D balance phase of competitive Tai Chi. The Vicon 3D motion capture system, Kistler 3D force platform, and Noraxon surface electromyography (sEMG) system were used to measure the joint angle, joint moment, center of gravity, ground reaction force, and sEMG data of athletes. The stability index was then calculated according to the formula. Pearson's or Spearman's correlation tests were used to analyze the associations between the biomechanical factors and stability index. (1) Medial lateral stability index (MLSI): A significant negative correlation was found between the ankle inversion angle of the supporting leg (SL) and MLSI (p < 0.05). (2) Anterior posterior stability index (APSI): Significant negative correlations were observed between the ankle intorsion angle, integrated electromyography (iEMG) of the gastrocnemius, and muscle contribution rates of the tibialis anterior, external oblique, and gastrocnemius of the non-supporting leg (NL) with the APSI (p < 0.05). The ankle dorsiflexion moment, iEMG of the rectus femoris and tibialis anterior, muscle contribution rate of the biceps femoris, and root mean-squared (RMS) amplitude of the gluteus maximus of the SL also showed significant negative correlations with the APSI (p < 0.05). Strong and significant negative correlations were also identified between the hip intorsion angle, iEMG of the tibialis anterior, and RMS amplitude of the rectus femoris of the NL with the APSI (p < 0.01). Further strong and significant negative correlation was also found between the RMS amplitude of the biceps femoris of the SL and APSI (p < 0.01). The knee extorsion angle of the NL was positively correlated with the APSI (p < 0.05). (3) Dynamic postural stability index (DPSI): The knee adduction angle, iEMG of the tibialis anterior, and RMS amplitude of the erector spinae of the NL were significantly positively correlated with the DPSI (p < 0.05). The knee abduction and hip extension moments of the SL were also significantly positively correlated with the DPSI (p < 0.05). The ankle inversion angle of the SL impacts left-right stability, while the NL's hip and ankle intorsion angles, knee extorsion angle, and exertion on the core muscle and SL's main muscles, as well as exertion of specific muscles of the NL affect anterior-posterior stability. The hip extension and knee abduction moments of the SL, knee adduction angle, exertion on the tibialis anterior, and activation of the erector spinae of the NL significantly affect the overall stability of an athlete.

Using 2D U-Net convolutional neural networks for automatic acetabular and proximal femur segmentation of hip MRI images and morphological quantification: a preliminary study in DDH

BackgroundDevelopmental dysplasia of the hip (DDH) is a common pediatric orthopedic condition characterized by varying degrees of acetabular dysplasia and hip dislocation. Current 2D imaging methods often fail to provide sufficient anatomical detail for effective treatment planning, leading to higher rates of misdiagnosis and missed diagnoses. MRI, with its advantages of being radiation-free, multi-planar, and containing more anatomical information, can provide the crucial morphological and volumetric data needed to evaluate DDH. However, manual techniques for measuring parameters like the center–edge angle (CEA) and acetabular index (AI) are time-consuming. Automating these processes is essential for accurate clinical assessments and personalized treatment strategies.MethodsThis study employed a U-Net-based CNN model to automate the segmentation of hip MRI images in children. The segmentation process was validated using a leave-one-out method during training. Subsequently, the segmented hip joint images were utilized in clinical settings to perform automated measurements of key angles: AI, femoral neck angle (FNA), and CEA. This automated approach aimed to replace manual measurements and provide an objective reference for clinical assessments.ResultsThe U-Net-based network demonstrates high effectiveness in hip segmentation compared to manual radiologist segmentations. In test data, it achieves average DSC values of 0.9109 (acetabulum) and 0.9244 (proximal femur), with a 91.76% segmentation success rate. The average ASD values are 0.3160 mm (acetabulum) and 0.6395 mm (proximal femur) in test data, with Ground Truth (GT) edge points and predicted segmentation maps having a mean distance of less than 1 mm. Using automated segmentation models for clinical hip angle measurements (CEA, AI, FNA) shows no statistical difference compared to manual measurements (p > 0.05).ConclusionUtilizing U-Net-based image segmentation and automated measurement of morphological parameters significantly enhances the accuracy and efficiency of DDH assessment. These methods improve precision in automatic measurements and provide an objective basis for clinical diagnosis and treatment of DDH.

AI-smartphone markerless motion capturing of hip, knee, and ankle joint kinematics during countermovement jumps.

Recently, AI-driven skeleton reconstruction tools that use multistage computer vision pipelines were designed to estimate 3D kinematics from 2D video sequences. In the present study, we validated a novel markerless, smartphone video-based artificial intelligence (AI) motion capture system for hip, knee, and ankle angles during countermovement jumps (CMJs). Eleven participants performed six CMJs. We used 2D videos created by a smartphone (Apple iPhone X, 4K, 60 fps) to create 24 different keypoints, which together built a full skeleton including joints and their connections. Body parts and skeletal keypoints were localized by calculating confidence maps using a multilevel convolutional neural network that integrated both spatial and temporal features. We calculated hip, knee, and ankle angles in the sagittal plane and compared it with the angles measured by a VICON system. We calculated the correlation between both method's angular progressions, mean squared error (MSE), mean average error (MAE), and the maximum and minimum angular error and run statistical parametric mapping (SPM) analysis. Pearson correlation coefficients (r) for hip, knee, and ankle angular progressions in the sagittal plane during the entire movement were 0.96, 0.99, and 0.87, respectively. SPM group-analysis revealed some significant differences only for ankle angular progression. MSE was below 5.7°, MAE was below 4.5°, and error for maximum amplitudes was below 3.2°. The smartphone AI motion capture system with the trained multistage computer vision pipeline was able to detect, especially hip and knee angles in the sagittal plane during CMJs with high precision from a frontal view only.

Interlaboratory Study Toward Combining Gait Kinematics Data Sets of Long-Distance Runners.

The limited sample size in gait studies has hampered progress in the field. This challenge could be addressed through multicenter studies, thereby leveraging data sets from different laboratories. This study compared 3-dimensional lower-extremity running kinematics between the Biomechanics and Motor Control Laboratory, Federal University of ABC (Brazil), and the Running Injury Clinic, University of Calgary (Canada). Three-dimensional lower-extremity kinematics from 23 male runners were collected from each laboratory using comparable instrumentation and experimental procedures. The 3-dimensional hip, knee, and ankle angles were compared within and between centers using root-mean-square deviation. Two-sample t tests Statistical Parametric Mapping tested the hypothesis that the data from both laboratories were not different. The sagittal plane hip, knee, and ankle angles were similar between laboratories, while notable differences were observed for frontal (hip and ankle) and transverse (hip and knee) plane angles. The average interlaboratory root-mean-square deviation (2.6°) was lower than the intralaboratory root-mean-square deviation (Biomechanics and Motor Control = 4.8°, Running Injury Clinic = 5.6°), with the ankle transverse angle displaying the smallest, and the knee transverse angle displaying the largest variability. This study demonstrates the potential of combining gait kinematics data from different laboratories to increase sample size, but frontal and transverse plane data should be considered with caution.

Development of a Gait Analysis Application for Assessing Upper and Lower Limb Movements to Detect Pathological Gait.

Pathological gait in patients with Hakim's disease (HD, synonymous with idiopathic normal-pressure hydrocephalus; iNPH), Parkinson's disease (PD), and cervical myelopathy (CM) has been subjectively evaluated in this study. We quantified the characteristics of upper and lower limb movements in patients with pathological gait. We analyzed 1491 measurements of 1 m diameter circular walking from 122, 12, and 93 patients with HD, PD, and CM, respectively, and 200 healthy volunteers using the Three-Dimensional Pose Tracker for Gait Test. Upper and lower limb movements of 2D coordinates projected onto body axis sections were derived from estimated 3D relative coordinates. The hip and knee joint angle ranges on the sagittal plane were significantly smaller in the following order: healthy > CM > PD > HD, whereas the shoulder and elbow joint angle ranges were significantly smaller, as follows: healthy > CM > HD > PD. The outward shift of the leg on the axial plane was significantly greater, as follows: healthy < CM < PD < HD, whereas the outward shift of the upper limb followed the order of healthy > CM > HD > PD. The strongest correlation between the upper and lower limb movements was identified in the angle ranges of the hip and elbow joints on the sagittal plane. The lower and upper limb movements during circular walking were correlated. Patients with HD and PD exhibited reduced back-and-forth swings of the upper and lower limbs.

Early gait analysis after total knee arthroplasty based on artificial intelligence dynamic image recognition

To explore early postoperative gait characteristics and clinical outcomes after total knee arthroplasty (TKA). From February 2023 to July 2023, 26 patients with unilateral knee osteoarthritis (KOA) were treated with TKA, including 4 males and 22 females, aged from 57 to 85 years old with an average of (67.58±6.49) years old;body mass index (BMI) ranged from 18.83 to 38.28 kg·m-2 with an average of (26.43±4.15) kg·m-2;14 patients on the left side, 12 patients on the right side;according to Kellgren-Lawrence(K-L) classification, 6 patients with grade Ⅲ and 20 patients with grade IV;the courses of disease ranged from 1 to 14 years with an average of (5.54±3.29) years. Images and videos of standing up and walking, walking side shot, squatting and supine kneeling were taken with smart phones before operation and 6 weeks after operation. The human posture estimation framework OpenPose were used to analyze stride frequency, step length, step length, step speed, active knee knee bending angle, stride length, double support phase time, as well as maximum hip flexion angle and maximum knee bending angle on squatting position. Western Ontario and McMaster Universities (WOMAC) arthritis index and Knee Society Score (KSS) were used to evaluate clinical efficacy of knee joint. All patients were followed up for 5 to 7 weeks with an average of (6.00±0.57) weeks. The total score of WOMAC decreased from (64.85±11.54) before operation to (45.81±7.91) at 6 weeks after operation (P<0.001). The total KSS was increased from (101.19±9.58) before operation to (125.50±10.32) at 6 weeks after operation (P<0.001). The gait speed, stride frequency and stride length of the affected side before operation were (0.32±0.10) m·s-1, (96.35±24.18) steps·min-1, (0.72±0.14) m, respectively;and increased to (0.48±0.11) m·s-1, (104.20±22.53) steps·min-1, (0.79±0.10) m at 6 weeks after operation (P<0.05). The lower limb support time and active knee bending angle decreased from (0.31±0.38) s and (125.21±11.64) ° before operation to (0.11±0.04) s and (120.01±13.35) ° at 6 weeks after operation (P<0.05). Eleven patients could able to complete squat before operation, 13 patients could able to complete at 6 weeks after operation, and 9 patients could able to complete both before operation and 6 weeks after operation. In 9 patients, the maximum bending angle of crouching position was increased from 76.29° to 124.11° before operation to 91.35° to 134.12° at 6 weeks after operation, and the maximum bending angle of hip was increased from 103.70° to 147.25° before operation to 118.61° to 149.48° at 6 weeks after operation. Gait analysis technology based on artificial intelligence image recognition is a safe and effective method to quantitatively identify the changes of patients' gait. Knee pain of KOA was relieved and the function was improved, the supporting ability of the affected limb was improved after TKA, and the patient's stride frequency, stride length and stride speed were improved, and the overall movement rhythm of both lower limbs are more coordinated.

Accuracy Validation of a Sensor-Based Inertial Measurement Unit and Motion Capture System for Assessment of Lower Limb Muscle Strength in Older Adults-A Novel and Convenient Measurement Approach.

(1) Background: The aim of this study was to assess lower limb muscle strength in older adults during the transfer from sitting to standing (STS) using an inertial measurement unit (IMU). Muscle weakness in this population can severely impact function and independence in daily living and increase the risk of falls. By using an IMU, we quantified lower limb joint moments in the STS test to support health management and individualized rehabilitation program development for older adults. (2) Methods: This study involved 28 healthy older adults (13 males and 15 females) aged 60-70 years. The lower limb joint angles and moments estimated using the IMU were compared with a motion capture system (Mocap) (pair t-test, ICC, Spearman correlations, Bland-Altman plots) to verify the accuracy of the IMU in estimating lower limb muscle strength in the elderly. (3) Results: There was no significant difference in the lower limb joint angles and moments calculated by the two systems. Joint angles and moments were not significantly different (p > 0.05), and the accuracy and consistency of the IMU system was comparable to that of the Mocap system. For the hip, knee, and ankle joints, the ICCs for joint angles were 0.990, 0.989, and 0.885, and the ICCs for joint moments were 0.94, 0.92, and 0.89, respectively. In addition, the results of the two systems were highly correlated with each other: the r-values for hip, knee, and ankle joint angles were 0.99, 0.99, and 0.96, and the r-values for joint moments were 0.92, 0.96, and 0.85. In the present study, there was no significant difference (p > 0.05) between the IMU system and the Mocap system in calculating lower limb joint angles and moments. (4) Conclusions: This study confirms the accuracy of the IMU in assessing lower limb muscle strength in the elderly. It provides a portable and accurate alternative for the assessment of lower limb muscle strength in the elderly.

Effects of Technique Asymmetry on 500 m Speed Skating Performance.

This study aimed to determine the effects of technique asymmetry on 500 m straight-track speed skating performance. We analyzed 20 elite skaters, measuring their joint angles, center of mass shift, and times and speeds during the gliding and push-off phases. The technique asymmetry index (ASI) was calculated for each parameter, and paired t-tests were used to compare bilateral asymmetry. Spearman correlation coefficients assessed the relationship between the ASI and both the average straight track speed and overall performance. Significant bilateral asymmetries in the knee, push-off, trunk, and hip angles were found in both male and female participants (p < 0.05). The male participants demonstrated a higher right push-off speed (p = 0.029) and a longer left gliding time (p = 0.048). Significant asymmetry was also observed in the lateral shift of the center of mass during each phase of the straight-track skating gait cycle (p < 0.001). No significant correlation was found between the ASIs and the overall performance (p ≥ 0.067). These findings indicate that while elite speed skaters demonstrated significant bilateral technique asymmetry in straight track skating, these asymmetries did not significantly impact their overall performance.