Motion Capture System Research Articles

DeepLabCut custom-trained model and the refinement function for gait analysis

The current gold standard for the study of human movement is the marker-based motion capture system that offers high precision but constrained by costs and controlled environments. Markerless pose estimation systems emerge as ecological alternatives, allowing unobtrusive data acquisition in natural settings. This study compares the performance of two popular markerless systems, OpenPose (OP) and DeepLabCut (DLC), in assessing locomotion. Forty healthy subjects walked along a 5 m walkway equipped with four force platforms and a camera. Gait parameters were obtained using OP “BODY_25” Pre-Trained model (OPPT), DLC “Model Zoo full_human” Pre-Trained model (DLCPT) and DLC Custom-Trained model (DLCCT), then compared with those acquired from the force platforms as reference system. Our results showed that DLCCT outperformed DLCPT and OPPT, highlighting the importance of leveraging DeepLabCut transfer learning to enhance the pose estimation performance with a custom-trained neural networks. Moreover, DLCCT, with the implementation of the DLC refinement function, offers the most promising markerless pose estimation solution for evaluating locomotion. Therefore, our data provide insights into the DLC training and refinement processes required to achieve optimal performance. This study proposes perspectives for clinicians and practitioners seeking accurate low-cost methods for movement assessment beyond laboratory settings.

Kinematic Alterations with Changes in Putting Distance and Slope Incline in Recreational Golfers

Golfers must modify their motor patterns when the demands of a putting task change. The objective was to compare joint angles and putter kinematics during putting at two distances and inclines. Recreational golfers (n = 14) completed putts over four conditions: 3-foot putts on flat and incline surfaces, and 7-foot putts on flat and incline surfaces. A Vicon motion capture system measured kinematic data. Joint angles, putter angles, and spatiotemporal variables were calculated. Analysis of variance compared spatiotemporal variables, and statistical parametric mapping compared angles between putts. There were faster putter head and ball velocities during longer and incline putts. The amplitude and time of backswing increased with longer putts. Longer putts resulted in increased trunk axial rotation during backswing, downswing, and follow-through, while incline putts only resulted in greater rotation during follow-through. There were minimal differences in shoulder angle. There was greater head rotation toward the hole during all putting phases for longer putts and during follow-through for incline putts. The trunk is the primary mechanism to increase putter head amplitude, and thereby velocity, when putting from longer distances. A similar strategy could be used when putting uphill. Additional work should confirm these results in highly skilled golfers.

Effect of Post-Activation Potentiation on Weightlifting Performance and Endocrinological Responses

Purpose: This study examined the acute performance-enhancing effects and endocrinological responses of a supramaximal clean pull performed at 120% of clean and jerk, one repetition maximum, on clean performance. Methods: Eight (n = 8) ranked collegiate level weightlifters attended two days of testing in a randomised order. A control session was used to identify a baseline measure of kinetic and kinematic clean performance and endocrinological status following three cleans interspersed with one-minute recovery between repetitions. The experimental condition required participants to perform a single clean pull at 120% of clean and jerk, one repetition maximum, followed by three minutes recovery, prior to executing three cleans with one-minute recovery between repetitions. All cleans were performed on a dual force plate set up, synchronised with a 3D motion capture system to simultaneously record barbell and ground reaction force data. All endocrinological data were measured prior to the participant warming up and also following each testing protocol. Results: The results indicated that no significant differences were found between the control and PAP condition (p = 0.140–0.902); however, effect sizes from group analysis identified moderately negative to trivial effects across kinetic, kinematic and endocrinological variables (d = −0.30–0.14). Further analysis on an individual level demonstrated values, both negative and positive, ranging from extremely large (d = −4.10) to trivial (d = 0.04). Conclusions: The findings suggest a potentially negative affect of PAP on kinetic and kinematic measures of clean performance. However, individual responses varied, and thus some weightlifters may find this useful.

Evaluating the impact of soft bracing and textile engineering in enhancing postural control and proprioception in adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is often associated with unbalanced posture and proprioceptive deficits and is particularly prone to progression during puberty. However, limited research has addressed early intervention for mild curves (10-20 degrees). This study aims to examine the effects of a soft bracing intervention using the Posture Correction Girdle (PCG) on 3D postural balance and proprioception in adolescents with early-stage scoliosis. Cobb angles were measured with the X-ray Imaging before and after a 2-h wear trial with the girdle to assess immediate curve reduction. Postural angles were visualized using 3D body scanning. Proprioception was assessed using a motion capture system, focusing on trunk, neck, elbow, and knee movements under the eye-open and eye-closed condition. Data were analyzed using descriptive statistics, t-tests, and Pearson’s correlation and partial Mantel tests to examine postural balance and proprioceptive outcomes. Results indicated significant improvements in postural balance in the frontal and sagittal planes, and proprioception in the dominant-side elbow. However, other proprioceptive measures showed limited changes, with responses differing by spinal curvature. Strong correlations emerged between proprioceptive function and postural angles in the thoracic and lumbar regions. These findings suggest that soft bracing can enhance postural control for mild AIS, though individual variability in responses highlights the need for personalized bracing strategies. This study supports soft bracing as a promising therapeutic option, underscoring the importance of individualized assessment to optimize brace design and effectiveness in early-onset scoliosis management.

Impact of backpack load during walking: an EMG and biomechanical analysis.

This study aims to understand the impact of backpack carriage, a regular activity for many, on back muscles and joint mobility during walking so that clinicians can develop strategies or products to ensure individuals' safety and well-being. Surface electromyography (EMG) and XSENS Awinda motion capture systems were used to analyze the effects of carrying a backpack (12% of body weight) on erector spinae and multifidus muscles, as well as spinal, hip, knee, and ankle joints. Subjects walked at 4km/h on flat and inclined surfaces. Paired t-tests compared backpack loads to baseline measurements. Carrying a backpack reduced activation levels in erector spinae and multifidus muscles and restricted spinal joint range of motion (axial and lateral bending, ). Hip joint rotation increased ( ). Moderate to strong correlations were observed between muscle activity and spinal joint ROM, notably with left erector spinae and L5-S1 lateral bending ( ). Backpack carriage decreases back muscle activation and alters the joint range of motion. Asymmetric correlations show that the subjects adapt muscle activity and gait patterns asymmetrically to manage external loads.

Estimating hip impact velocity and acceleration from video-captured falls using a pose estimation algorithm

Analyzing video footage of falls in older adults has emerged as an alternative to traditional lab studies. However, this approach is limited by the labor-intensive process of manually labeling body parts. To address this limitation, we aimed to validate the use of the AI-based pose estimation algorithm (OpenPose) in assessing the hip impact velocity and acceleration of video-captured falls. We analyzed 110 videos of 13 older adults (64.0 ± 5.9 years old) falling sideways in an experimental setting. By applying OpenPose to each video, we generated a time series of hip positions in the video, which were then analyzed using custom MATLAB code to calculate hip impact velocity and acceleration. These calculations were compared against ground truth measurements obtained from motion capture systems (VICON for hip impact velocity) and inertial measurement units (MC10 for hip impact acceleration). We examined the agreement between the ground truth and OpenPose measurements in terms of mean of absolute error (MAE), mean of absolute percentage error (MAPE), and bias (mean of error). Results showed that OpenPose had a good accuracy in estimating hip impact velocity with minimal bias (MAE: 0.17 ± 0.13 m/s, MAPE: 7.28 ± 5.21%; percent bias: − 1.27%). However, its estimation of hip impact acceleration (i.e., peak vertical hip acceleration at impact) showed poor accuracy (MAPE: 26.3 ± 19.4%), showing substantial underestimation in instances of high acceleration impacts (> 3.0 g). Further ANOVA analysis revealed OpenPose’s ability to discern significant differences in hip impact velocity and acceleration based on the movement response utilized during the fall (e.g., stick-like fall, tuck-and-roll, knee block). This is the first study to validate the use of a pose estimation algorithm for identifying the hip impact kinematics in video-captured falls among older adults. Future validation studies involving diverse camera settings, fall contexts, and biomechanical parameters are warranted to extend this support for using pose estimation algorithms in this field.

Effect of induced extrinsic and intrinsic hand and forearm muscular fatigue on the control of finger force during piano playing.

This study aimed to investigate the effect of hand muscle fatigue on finger control and force efficiency during piano performance, which is crucial for skilled piano playing among professional pianists engaged in prolonged periods of high-intensity practice or concert preparation. Thirty-one professional pianists were recruited as participants. This study was divided into three sequential experimental parts: pre-fatigue test, fatigue protocol, and post-fatigue test. Each participant was assigned eight piano skills and instructed to perform two fatigue tasks: finger extension and finger grasping exercises. The study recorded and analyzed the finger force of professional pianists using a sensor-embedded kinetic assessment piano system; wrist movements were assessed using a three-dimensional motion capture system. Paired t-tests were used to determine the differences between the pre- and post-tests. The findings showed that the average peak striking force of most fingers in Chords 1, 2, 4, 5, 6, and 7 decreased significantly after the fatigue task, indicating a reduction in the finger-striking force following fatigue across the various chord fingerings. The analysis of wrist movements demonstrated strategic adjustments made by pianists after experiencing fatigue, particularly in the ulnar/radial deviation movements. This study highlights the influence of muscle fatigue on finger control and wrist movements of pianists across different fingerings. We recommend that pianists focus on strengthening the extrinsic and intrinsic muscles of the hand and the muscle groups responsible for controlling ulnar/radial movements to mitigate the effects of muscular fatigue on hand performance.

Integrative biomechanics of a human–robot carrying task: implications for future collaborative work

Patients with sarcopenia, who face difficulties in carrying heavy loads, may benefit from collaborative robotic assistance that is modeled after human–human interaction. The objective of this study is to describe the kinematics and spatio-temporal parameters during a collaborative carrying task involving both human and robotic partners. Fourteen subjects carried a table while moving forward with a human and a robotic partner. The movements were recorded using a three-dimensional motion capture system. The subjects successfully completed the task of carrying the table with the robot. No significant differences were found in the shoulder and elbow flexion/extension angles. In human–human dyads, the center of mass naturally oscillated vertically with an amplitude of approximately 2 cm. The here presented results of the human–human interaction serve as a model for the development of future robotic systems, designed for collaborative manipulation.

Validation and Analysis of Recreational Runners’ Kinematics Obtained from a Sacral IMU

Our aim was to validate a sacral-mounted inertial measurement unit (IMU) for reconstructing running kinematics and comparing movement patterns within and between runners. IMU data were processed using Kalman and complementary filters separately. RMSE and Bland–Altman analysis assessed the validity of each filtering method against a motion capture system. Running data from 24 recreational runners were analyzed using Fourier transform coefficients, PCA, and k-means clustering. High agreement was found for Kalman-filtered data in the frontal, sagittal, and transverse planes, with a Bland–Altman bias of ~2 mm on average, compared to a bias of ~10.5 mm for complementary-filtered data. Pelvic angles calculated from Kalman-filtered data had superior agreement, with systematic biases of ~0.3 versus 3.4 degrees for complementary-filtered data. Our findings suggest that inertial sensors are viable alternatives to motion capture for reconstructing pelvic running kinematics and movement patterns. In the second part of our study, negligible intra-individual differences were observed with changes in speed, while inter-individual differences were large. Two clusters of runners were identified, each showing distinct movement patterns and ranges of motion. These observations highlight the potential usefulness of inertial sensors for performance analysis and rehabilitation as they may permit the use of individual-specific and cluster-specific practice programs.

WearMoCap: multimodal pose tracking for ubiquitous robot control using a smartwatch

We present WearMoCap, an open-source library to track the human pose from smartwatch sensor data and leveraging pose predictions for ubiquitous robot control. WearMoCap operates in three modes: 1) a Watch Only mode, which uses a smartwatch only, 2) a novel Upper Arm mode, which utilizes the smartphone strapped onto the upper arm and 3) a Pocket mode, which determines body orientation from a smartphone in any pocket. We evaluate all modes on large-scale datasets consisting of recordings from up to 8 human subjects using a range of consumer-grade devices. Further, we discuss real-robot applications of underlying works and evaluate WearMoCap in handover and teleoperation tasks, resulting in performances that are within 2 cm of the accuracy of the gold-standard motion capture system. Our Upper Arm mode provides the most accurate wrist position estimates with a Root Mean Squared prediction error of 6.79 cm. To evaluate WearMoCap in more scenarios and investigate strategies to mitigate sensor drift, we publish the WearMoCap system with thorough documentation as open source. The system is designed to foster future research in smartwatch-based motion capture for robotics applications where ubiquity matters. www.github.com/wearable-motion-capture.

Kinematic classification of mandibular movements in patients with temporomandibular disorders based on PCA

This retrospective study aimed to kinematically classify mandibular movements collected during Temporomandibular Disorders (TMD) treatment, employing Fourier transformation (FT), Principal Component Analysis (PCA), and K-means clustering (k-means), and to investigate their correlation with symptoms of pain-related TMD. The study included five TMD participants diagnosed with myalgia (age: 39–86 years, with an SD of 18.96) and three healthy participants (age: 32–42 years, with an SD of 5.13) with no stomatognathic problems. TMD participants underwent tailored treatment for their symptoms, and their maximum unassisted mouth opening (MMO) was recorded randomly with a motion capture system (ARCUS digma II, Kavo, Biberach, Germany) at multiple time points. MMO for healthy participants served as a control. The dataset comprising 28 trials, was transferred to the AnyBody Modeling System (AnyBody Technology, Aalborg, Denmark) to extract joint angle time series, which were then transformed into Fourier series. Subsequently, PCA and k-means clustering were conducted. Two clusters were identified: Cluster 1, predominantly composed of symptomatic trials, and Cluster 2, mainly consisting of asymptomatic trials. Distinct transition pathways between the clusters were observed among participants, corresponding to the alleviation of pain-related symptoms during TMD treatment. These findings suggest that this approach has potential as an effective tool for diagnosing and assessing TMD by identifying symptomatic kinematic patterns and tracking temporal changes in mandibular movement. Despite the small dataset, these results suggest promise for a novel functional assessment method for TMD based on kinematic features.

Biomechanical differences of Asian knee osteoarthritis patients during standing and walking using statistical parametric mapping: A cross-sectional study

BackgroundBiomechanics of knee osteoarthritis (KOA) patients have been extensively studied using motion capture systems, but less have explored standing knee joint angles with the walking parameters, particularly in Asians. We aim to determine gait biomechanical differences between healthy and KOA participants in an Asian population using One-dimensional Statistical Parametric Mapping (SPM1D) and explore if they are associated with standing joint angles. MethodsA total of 20 KOA and 24 healthy stood upright and walked 10 m at self-selected speeds. The standing angles, walking kinematic and kinetic parameters of the ankle, knee, hip and trunk were analysed. Lower limb muscle excitation was measured via electromyography. SPM1D was used to compare the healthy group with the KOA group, and for further subgroup analysis. ResultsThe all KOA group had significantly greater standing knee flexion angles (KFA) (p < 0.001), standing ankle dorsiflexion angles (ADA) (p < 0.001), walking KFA during terminal stance (p = 0.001) and terminal swing (p = 0.02) and walking ADA during terminal stance (p = 0.02) and mid-swing to terminal swing (p = 0.001). Knee adduction moment (p = 0.04) and knee flexion moment (p = 0.03) were higher in severe KOA. A positive correlation was found between standing KFA and initial KFA (R2 = 0.579), and mean walking KFA (R2 = 0.801) in the KOA group. ConclusionThe increase in standing KFA was associated with an increase in walking KFA in the KOA group. Static joint angles remain as an essential parameter, although further studies need to be carried out to determine if the increase in standing joint angles can be recommended as an adjunctive measure during gait analysis of KOA using motion capture.

Concurrent validity of skin-based motion capture systems in measuring dynamic lumbar intervertebral angles.

Spine kinematics are commonly measured by external sensors such as motion capture and accelerometers. However, these skin-based measures cannot directly capture intervertebral motion of the lumbar spine. To date, research in this area has focused on the estimation of intervertebral kinematics using static trials but no study has analyzed agreement throughout the dynamic range of motion. This study investigated the agreement between skin-based sensors (accelerometers and motion capture) and quantitative fluoroscopy (QF) in measuring lumbar spine kinematics for the duration of complete flexion and extension motion in a healthy female population. Twenty female participants (age 30-57, BMI<30) were guided through a standing flexion and extension bending protocol while spine kinematics were concurrently measured by QF (L2, L3, L4, L5, and S1) and motion capture sensors and accelerometers positioned over the spinous processes of L2, L4, and S1. Intervertebral angles (L2-L4, L4-S1, L2-S1) and individual vertebrae levels were compared between measures. Non-parametric limits of agreement between QF and skin-based markers were greatest at the end-range of motion for both flexion and extension, but differences increased variably between participants, sometimes over-and sometimes underestimating angles, thus, disproving the common assumption that it increases linearly. The two skin-based marker systems showed good agreement with one another showing that they can be used interchangeably but they can only be used to estimate lumbar spine kinematics. Normalizing angles to a change in angle and considering the posture of instrumentation would be beneficial to reduce potential sources of errors.

Differences of simulated ankle dorsiflexion limitation on lower extremity biomechanics during long jump takeoff.

The long jump is an athletic event that demands speed, power, force application, and balance, with each phase being critical to overall performance. However, previous research has neglected the limiting effect of the wedge pedals on ankle dorsiflexion range of motion. This cross-sectional study investigated biomechanical changes in the lower extremities during long jumps under varying degrees of ankle dorsiflexion. Thirty male Division II long jump athletes executed jumps under three conditions: no dorsiflexion, with 10° dorsiflexion restriction, and with 20° dorsiflexion restriction. A Vicon motion capture system with eight cameras and an AMTI force platform were used to collect biomechanical data simultaneously during the long jump. The angles, moments, and velocities of the ankle, hip, and knee joints during takeoff were simulated and calculated using a musculoskeletal model. Between-group variations were assessed using one-way repeated measures ANOVA, with statistical parametric mapping (SPM1D) applied for analysis. Results showed that as ankle restriction increased, vertical velocity gain increased: NW (3.34±0.21m/s), 10W (3.65±0.14m/s), and 20W (3.77±0.12m/s) (p<0.001). Horizontal velocity loss was significantly higher only at 20W (p=0.002). Peak extension angle, angular velocity, and power were highest at 10W for the knee and hip joints (p<0.05). Joint forces at the ankle, knee, and hip were significantly affected by different pedal angles (p<0.001). Athletes with a 10° ankle dorsiflexion limit showed increased vertical velocity with minimal horizontal velocity loss, potentially enhancing performance. This limit also increased muscle co-activation around the knee, possibly stabilizing it. Athletes should consider a 10° ankle dorsiflexion limit in training to improve performance and reduce injury risk.

Inclined distance running at iso-efficient speeds: Effect on joint work

ABSTRACT Runners often reduce their pace during inclined running to maintain a constant metabolic workload, known as iso-efficiency speed (a speed-incline combination with the same metabolic intensity as level running). This study investigates changes in lower extremity (LE) joint work profiles when running on an incline at iso-efficiency speed. Eleven collegiate distance runners completed a treadmill running task under three conditions (0%, 4%, and 8% incline). Running velocity was reduced with increasing incline to ensure a consistent metabolic workload across conditions. An 8-camera motion capture system and an instrumented treadmill collected kinematics and ground reaction forces. Visual 3D was used to calculate ankle, knee, and hip joint powers, while custom software (MATLAB) calculated ankle, knee, and hip joint positive and negative work values. A significant increase in LE total positive work was attributed to greater ankle and hip joint positive work with steeper inclines. Reduced LE total negative work resulted from lower knee and hip joint negative work as incline increased. Results suggest that at iso-efficiency speeds, inclined treadmill running increases eccentric demands on the ankle joint and concentric demands on the ankle and hip joints, benefiting training programmes to optimize cardiorespiratory stimuli while reducing mechanical demand on specific extremity structures.

Evaluating the efficacy of hinged elbow braces in reducing passive valgus forces after ulnar collateral ligament injury-A biomechanical study.

This biomechanical study aimed to investigate the effectiveness of a hinged elbow orthosis in reducing passive valgus forces following medial ulnar collateral ligament (UCL) injuries of the elbow joint. The hypothesis tested was that a hinged elbow orthosis reduces these passive valgus forces. Eight fresh frozen cadaveric elbow specimens were prepared and tested under three scenarios: intact ligaments, simulated UCL rupture and application of a hinged elbow brace after simulated UCL rupture. Valgus instability was assessed using a custom testing set-up and the Optotrak motion capture system. Statistical analysis was conducted to compare the results across scenarios. Intraclass correlation (ICC) calculation showed that the testing set-up was reliable in investigating valgus deflection across all levels of applied force. The hinged elbow brace reduced passive valgus forces after UCL rupture. The reduction in valgus instability was consistent with close approximation to the native state, although not reaching its level. The hypothesis-that a hinged elbow orthosis significantly reduces passive valgus forces in the elbow following UCL injuries-is not supported by the data and therefore has to be rejected. Nevertheless, the study demonstrates a tendency that a hinged elbow brace could mitigate these forces, at least in an experimental cadaveric model with static study conditions. The level of evidence of this study is level IV.

Effects of kinesio taping on lower limb biomechanical characteristics during dynamic postural control tasks in individuals with chronic ankle instability.

Previous studies have demonstrated significant biomechanical differences between individuals with chronic ankle instability (CAI) and healthy controls during the Y-balance test. This study aimed to examine the effects of kinesio taping (KT) on lower limb biomechanical characteristics during the Y-balance anterior reach task in individuals with CAI. A total of 30 participants were recruited, comprising 15 individuals with CAI and 15 healthy controls. All participants were randomly assigned three taping conditions: no taping (NT), placebo taping (PT), and KT, followed by the Y-balance anterior reach task. Each condition was separated by one-week intervals. Kinematic and kinetic data of the lower limbs during the movement phase were collected using the Vicon motion capture system (Vicon, T40, 200 Hz) and two Kistler force platforms (Kistler, 1000 Hz). KT significantly improved the Y-balance anterior reach distance (P = 0.003) and peak ankle eversion angle (P = 0.019) compared to NT. Additionally, KT resulted in increased peak knee flexion angle (P = 0.002, P = 0.011) and peak ankle dorsiflexion angle (P <0.001, P = 0.005) relative to both NT and PT. KT also significantly reduced mediolateral center of pressure (COP) displacement (P = 0.001) and average velocity of mediolateral COP displacement (P = 0.033) in comparison to NT. Furthermore, KT decreased mediolateral center of gravity displacement (P = 0.002, P = 0.003) relative to both NT and PT. KT significantly improved abnormal ankle posture by promoting greater ankle dorsiflexion and eversion angles. Additionally, KT reduced mediolateral COP displacement and average velocity to improve postural stability. These changes may contribute to reduced risk of ankle sprains. Therefore, KT may serve as an effective tool for managing recurrent ankle sprains in individuals with CAI.

Real-time, accurate, and open source upper-limb musculoskeletal analysis using a single RGBD camera — An exploratory hand-cycling study

Biomechanical biofeedback may enhance rehabilitation and provide clinicians with more objective task evaluation. These feedbacks often rely on expensive motion capture systems (∼$100000), which restricts their widespread use, leading to the development of computer vision-based methods. These methods are subject to large joint angle errors, considering the upper limb, and exclude the scapula and clavicle motion in the analysis. Our open-source approach offers a user-friendly solution for high-fidelity upper-limb kinematics using a single consumer-grade depth-sensing camera (∼$500) and includes semi-automatic skin marker labeling. Real-time biomechanical analysis, ranging from kinematics to muscle force estimation, was conducted on eight participants performing a hand-cycling motion to demonstrate the applicability of our approach on the upper limb. Markers were recorded by the depth-sensing camera and an optoelectronic camera system, considered as a reference. Muscle activity and external load were recorded using eight electromyography sensors and instrumented hand pedals, respectively. Bland-Altman analysis revealed significant agreements in the 3D markers’ positions between the two motion capture methods, with errors averaging 3.3 ± 3.9 mm. The error propagation was low for the biomechanical analysis, with joint angle differences, for example, below 5° when comparing both systems. Biofeedback from the depth-sensing camera was provided at 68 Hz. Our study introduces a novel method for using a depth-sensing camera as a low-cost motion capture solution. Results from healthy participants suggest its potential for accurate kinematic reconstruction and comprehensive upper-limb biomechanical studies. Further investigation is needed to explore its clinical applications in pathological populations.

Effect of hand-wrist exercises on distal radius fracture healing based on markerless motion capture system.

With the internal volar locking plate (VLP) technique emerging as a preferred surgical approach, early post-surgery therapeutic exercises have shown promise in promoting wrist functionality after distal radial fractures (DRFs). The biomechanical microenvironment, particularly the role of biomechanical stimuli, plays a crucial role in guiding stem tissue formation at the fracture site. However, much less is known about how various hand exercises interact with the microenvironment and influence fracture healing outcomes. This study employed the Leap Motion Controller for markerless hand motion capture and utilised an enhanced OpenSim hand model to simulate these motions. An advanced DRF healing model, integrating angiogenesis and the mechano-regulated maturation of callus tissue, was applied to simulate the MSCs differentiation and predict the healing outcomes. The effects of various rehabilitation exercises on DRFs' healing outcomes were systematically analysed. The results showed rehabilitation exercises, such as wrist extension/flexion and ulnar deviation, generally had a higher contact force on the distal radius compared with the slack state. Also, the relationship between contact force and muscle activations was not always linear, reflecting the intricate dynamics of the kinematic system. Exercise could induce changes in the bony bridge and cartilage formation, while angiogenesis remained unaffected. In the initial weeks, gripping exercises proved most beneficial, but as time progressed, extension and flexion exercises became more advantageous. The study highlights the importance of tailoring rehabilitation exercises to the dynamic healing process of DRFs. As the healing trajectory progresses, the therapeutic efficacy of specific exercises evolves, necessitating adaptive and patient-specific rehabilitation programs.

Normative values of spinal and peripheral proprioception in position sense among healthy adolescents and young adults

Establishing normative values and understanding how proprioception varies among body parts is crucial. However, the variability across individuals, especially adolescents, makes it difficult to establish norms. This prevents further investigation into classifying patients with abnormal proprioception. Therefore, the primary objective was to address the knowledge gap using three-dimensional motion analysis to capture position sense in adolescents and young adults. The secondary objective was to evaluate the relationship between position sense and age, as well as the interrelationships of position senses across various anatomical sites. Healthy participants aged 10 to 25 years were included. Six position sense tests were implemented on the trunk, neck, elbow, and knee. Data were captured using a three-dimensional motion capture system. The proprioceptive measure was the absolute repositioning error (the difference between the destinated starting position and the corresponding self-reproduced ending position) of each test. A total of 103 participants were recruited. We found that only spinal proprioception was associated with chronological age, whereas peripheral proprioception was not. Subgroup analyses revealed that subjects aged 10 to 13 years had the poorest proprioceptive performance. The normative values of proprioception of various body parts were, trunk flexion-extension test = 25° ± 12°; trunk lateral-flexion test = 23° ± 10°; trunk axial-rotation test = 26° ± 11°; left neck rotation test = 2° ± 1°; right neck rotation test = 3° ± 1°; left elbow flexion test = 5° ± 3°; right elbow flexion test = 5° ± 2°; left knee extension test = 3° ± 2°; right knee extension test = 3° ± 1°. The normative values of proprioception in position sense provided in this study may help identify individuals with proprioceptive deficits and inform targeted interventions to improve proprioception.