Search Results (440)

Background and Objectives: In degenerative spine disease, compensatory mechanisms are activated to maintain upright posture, extending beyond the spine to involve the pelvis, lower limbs, and feet. These adaptations may be accompanied by differences in foot alignment, which could be associated with sagittal balance. The aim of this study is to investigate the relationship between foot alignment and spinal posture in patients with degenerative spine disease and evaluate whether foot deformities are associated with sagittal imbalance in degenerative spine disease. Materials and Methods: We retrospectively reviewed 98 patients with degenerative spine disease who underwent preoperative standing EOS imaging between 2017 and 2025 at a single academic spine centre. Meary’s angle, talocalcaneal angle, and calcaneal pitch were measured on lateral EOS images to classify feet as flat, normal, or cavus. Spinopelvic parameters were extracted from EOS and conventional radiographs. Differences in spinal parameters across foot groups were compared using ANOVA, and linear regression evaluated associations between sagittal vertical axis (SVA) and foot angles. Results: Among spinopelvic parameters, only SVA significantly differed between foot groups, with flatfoot patients showing greater forward imbalance (p = 0.035). Regression analysis demonstrated an inverse relationship between SVA and both talocalcaneal angle (p = 0.003) and calcaneal pitch (p = 0.034), suggesting that greater forward trunk inclination was associated with flatter feet. Degenerative scoliosis patients demonstrated a bimodal pattern with more flat and cavus feet (p = 0.006), while herniated disc patients more often exhibited flatfoot (p = 0.031). Conclusions: Foot posture abnormalities, particularly flatfoot, are associated with sagittal spinal imbalance, suggesting foot posture may be associated with global alignment and could reflect distal postural adaptations. Full article

Background/Objectives: Statistical shape modeling (SSM) is used to describe transtibial residual-limb morphology for prosthetic socket design, simulation, and future structural testing. However, conventional intrinsic metrics such as compactness, generality, and specificity may not directly reflect geometric fidelity to the original shape. This study examined the relationship between geometric fidelity and SSM evaluation and assessed a cross-sectional shape representation framework for transtibial residual limbs. Methods: Residual-limb surfaces were acquired from 62 adults with unilateral transtibial amputation using a structured-light 3D scanner while preserving habitual limb posture. Two surface-based registration methods, non-rigid iterative closest point and Bayesian coherent point drift, were compared with a cross-sectional representation in which proximal and distal regions were sectioned separately and reconstructed by strip triangulation. Geometric fidelity to the original mesh was quantified using average symmetric surface distance (ASSD). SSM performance was evaluated using compactness, generality, and specificity. Results: The optimal cross-sectional configuration was 60 sections × 72 points. The proposed method showed the best geometric fidelity (ASSD, 1.30 ± 0.14 mm), followed by Bayesian coherent point drift (1.33 ± 0.14 mm) and non-rigid iterative closest point (1.48 ± 0.48 mm). Compactness was highest for the proposed method, reaching 95% cumulative variance in four modes, compared with five and seven modes, respectively, for the two surface-based methods. In geometry-space evaluation, the proposed method showed the lowest specificity error, while differences in generality were statistically significant but small in magnitude. Conclusions: Intrinsic SSM metrics alone were insufficient to judge registration quality in transtibial residual-limb modeling. The cross-sectional representation preserved the original surface geometry more faithfully than the evaluated surface-based methods while maintaining competitive SSM performance. Full article

Background/Objectives: Evidence on the role of muscle mechanical (myotonic) properties in athletic performance remains limited in young adult and sub-elite populations, particularly in American football, and sex-specific patterns of association are not well understood. This study aimed to investigate the associations between lower extremity myotonic properties and performance outcomes (strength and balance) in American football athletes, with a specific focus on sex-related differences and candidate predictors. Methods: A cross-sectional design was implemented involving 35 American football athletes (17 female, 18 male). Lower extremity muscle tone, stiffness, and elasticity were assessed using MyotonPRO. Strength parameters (lower limb, handgrip, back, and shoulder internal rotation) and balance performance (static and dynamic under eyes-open and eyes-closed conditions) were evaluated using standardized measurement protocols. Pearson correlation analysis was conducted to examine bivariate associations, followed by Least Absolute Shrinkage and Selection Operator (LASSO) regression to determine candidate predictors while addressing multicollinearity. Results: Male athletes exhibited significantly greater height, body mass, and BMI (p < 0.001), alongside elevated myotonic values compared to females. Correlation analyses indicated distinct sex-specific association patterns between myotonic properties and performance metrics. LASSO regression revealed a distinct sex-specific divergence in strength prediction: female strength was predominantly driven by proximal musculature (quadriceps and hamstring elasticity/stiffness), whereas male strength was anchored by distal musculature (gastrocnemius tone/stiffness). Furthermore, rigorous penalization shrunk nearly all balance coefficients to zero in both sexes, indicating that resting myotonic properties do not independently predict dynamic or static postural control. Conclusions: While lower extremity myotonic properties are candidate predictors of multi-regional strength via sex-specific proximal and distal strategies, they do not independently predict balance performance, suggesting postural control relies primarily on active motor recruitment rather than passive resting mechanics. Given the cross-sectional design of this study, causal inferences cannot be drawn, and these findings should be interpreted accordingly. The observed sex-specific differences may support consideration of individualized, sex-informed training strategies in American football athletes. Full article

(1) Background: Changes in midsole hardness may affect lower-limb impact loading during forefoot strike (FFS) running in children, yet the biomechanical basis for discriminating elevated VALR-related loading remains unclear. (2) Methods: Fourteen school-aged boys performed FFS running tests in experimental shoes with four midsole hardness levels (37, 42, 47, and 52 Shore C). Lower-limb kinematics and surface electromyography (sEMG) data were collected during the dominant leg stance phase. After preprocessing, VALR was calculated from 336 valid trials, and 28 stance-phase biomechanical features were extracted, yielding a final machine-learning dataset of 324 trials after excluding incomplete feature data. VALR was used to compare loading changes and define trial-level elevated-loading labels based on the median VALR value. Classification models were evaluated under participant-level GroupKFold validation, and XGBoost was retained for exploratory SHAP analysis. (3) Results: VALR showed an upward trend with increasing hardness, but no statistically supported change point was identified. XGBoost achieved an accuracy of 75.93%, precision of 74.14%, recall of 79.63%, F1-value of 0.768, and pooled out-of-fold AUC of 0.738. SHAP analysis indicated that distal and non-sagittal kinematic features contributed most to model classification. (4) Conclusions: Elevated VALR-related loading during children’s FFS running may be characterized by a multi-feature model-based pattern rather than a fixed midsole hardness threshold. Full article

Renal tubular disorders are often overlooked causes of acquired or inherited bone hypomineralization and fragility fractures in adults. The proximal tubule reabsorbs glucose, phosphate, low-molecular-weight proteins, amino acids, bicarbonate, and much of the sodium, potassium, chloride, and calcium. The distal nephron—the thick ascending limb of the loop of Henle, the distal convoluted tubule, and the collecting duct—regulates urine concentration and dilution, maintains acid-base balance via urinary proton secretion, and controls electrolytes, including sodium, potassium, magnesium, and calcium. Tubular defects may cause hyperphosphaturia (high urinary phosphate), hypercalciuria (high urinary calcium), or chronic metabolic acidosis (renal tubular acidosis, RTA). These changes weaken bone mineralization, disrupt bone turnover, and raise the risk of muscle weakness and fractures. This review summarizes acquired and genetic tubulopathies linked to hyperphosphaturia, hypercalciuria, and RTA and outlines a practical diagnostic approach for outpatients with bone fragility and suspected renal tubulopathy. Full article

Background/Objectives: Alignment philosophy in total knee arthroplasty (TKA) may affect joints beyond the knee. Mechanical alignment (MA) targets a neutral mechanical axis, whereas kinematic alignment (KA) aims to restore native alignment and joint line obliquity (JLO). This study compares the effects of MA and KA on hip and ankle radiographic parameters and investigates the propagation of coronal correction along the lower limb. Methods: A retrospective comparative study evaluated 63 TKAs performed for varus deformity (KA: n = 32; MA: n = 31). Pre- and postoperative full-length standing radiographs were used to calculate changes (Δ), defined as the difference between postoperative and preoperative values, in hip offsets, mechanical and arithmetic hip–knee–ankle angles (mHKA, aHKA), medial proximal tibial angle (MPTA), lateral distal femoral angle (LDFA), JLO, and ankle ground-referenced angles. Between-group differences and correlations were analysed. Interobserver reliability was assessed for all variables. Results: MA produced significantly greater limb correction than KA (ΔmHKA: 8.89° vs. 4.82°, p < 0.001), primarily due to increased tibial valgus correction (ΔMPTA: 6.26° vs. 2.41°, p < 0.001). JLO increased substantially with MA (+4.10°) but was preserved with KA (+0.30°, p < 0.001). MA resulted in significant valgus shifts at the ankle (ground talar dome angle (GTDA) −3.01°, ground tibial plafond angle (GTPA) −3.02°; p = 0.006 for both), whereas KA produced no significant ankle changes. Correlation analysis demonstrated limited knee–ankle biomechanical coupling, with a moderate negative correlation in MA (ΔmHKA vs. ΔGTDA: ρ = −0.479, p = 0.006) and a weak correlation in KA (ΔaHKA vs. ΔGTDA: ρ = −0.360, p = 0.043). Hip parameters remained unchanged in both groups. Conclusions: Mechanical alignment induces larger tibial-driven coronal corrections, increases joint line obliquity, and produces measurable valgus shift at the ankle. In contrast, kinematic alignment preserves native alignment and joint-line obliquity while minimising distal ankle compensatory changes. Full article

Objective: This study aimed to compare the neuromuscular control characteristics of international- and national-level squash players during forehand strokes using a multichannel surface electromyography (sEMG)-based sensing framework. By integrating wearable biosignal acquisition with muscle synergy and intermuscular coherence analyses, this study sought to identify sensor-derived markers of performance-related neuromuscular control and to provide evidence for sensor-informed squash training and athlete monitoring. Methods: Participants performed standardized forehand strokes, during which multichannel sEMG signals were synchronously collected from major upper-limb, lower-limb, and trunk muscles. The recorded sensor signals were preprocessed and analyzed using non-negative matrix factorization to extract muscle synergies, including the number of synergies, muscle weightings, and synergy activation durations. In addition, time–frequency intermuscular coherence analysis was performed on the sEMG sensor data to quantify coherence differences in the α, β, and γ frequency bands between upper-limb–trunk and lower-limb–trunk muscle pairs. Results: No significant difference was found between the two groups in the number of muscle synergies, with both groups clustering into four synergy modules. However, the sEMG sensor-based analysis revealed clear between-group differences in synergy structure and coordination patterns. International-level players showed higher muscle weightings in major proximal muscles, including the deltoid, pectoralis major, erector spinae, and gluteus maximus, and lower weightings in relatively smaller or more distal muscles such as the biceps brachii and lateral gastrocnemius. In terms of synergy timing, international-level players exhibited significantly shorter activation durations in SYN1 and SYN2, but a significantly longer activation duration in SYN3, than national-level players. For intermuscular coherence, international-level players showed significantly lower coherence in the α, β, and γ bands for multiple upper-limb–trunk and lower-limb–trunk muscle pairs. Conclusions: A multichannel sEMG sensing approach was effective in detecting performance-level differences in neuromuscular control during the squash forehand stroke. International-level players exhibited more efficient and refined neuromuscular coordination, characterized by optimized proximal muscle recruitment, more task-specific synergy timing, and reduced intermuscular coherence across selected muscle pairs. These findings highlight the value of wearable EMG sensors and sensor-based neuromuscular feature extraction for quantitative athlete assessment, movement monitoring, and the development of sensor-guided training strategies in squash. Full article

Background: Severe knee trauma and chronic cruciate ligament insufficiency are commonly accompanied by marked quadriceps femoris (QF) atrophy and weakness. High-load strengthening is often poorly tolerated by patients with compromised joint stability; therefore, low-load blood flow restriction resistance training (LL-BFRT) may serve as an effective alternative. Case presentation: A 38-year-old male presented 27 months after motorcycle-related polytrauma with right knee pain, instability, complete anterior and posterior cruciate ligament ruptures, and partial QF denervation after femoral nerve injury. Before surgery, he completed a supervised 5-week LL-BFRT prehabilitation program (13 sessions). Results: Lean thigh circumference increased by 5.9% proximally and 17.7% distally. Voluntary activation increased from 87.2% to 92.5%, and maximal QF EMG median frequency decreased by 7.4%. Knee extensor isometric and concentric (60°/s) peak torque increased by 52.4% and 36.9%, respectively. QF isometric endurance time increased from 48.5 to 61.8 s. Stair-climbing time decreased from 18.9 to 10.6 s, repetitions in the step-down test increased from 10 to 17, and the Y-balance test composite score increased from 77.7% to 99.4%. Conclusions: Substantial physiological and clinical improvements in QF voluntary activation, maximal strength, endurance, and lower limb function were observed following a short-term LL-BFRT program in a patient with multiple ligament injuries. Changes in lean thigh circumference were consistent with possible improvements in muscle size; however, muscle hypertrophy was not directly assessed. Full article

Background: Distal radius fractures (DRFs) are the most common upper limb fractures worldwide. The main goal of DRF treatment is to achieve optimal functional outcomes with the lowest complication rate as rapidly as possible. Achieving full limb function may be delayed by emerging complications or, in some cases, may never occur. Preserving muscle strength and as full a range of motion (ROM) in the wrist as possible are key in DRF management since they enable patients to perform the activities of daily living. The purpose of this study was to assess the effect of ossein–hydroxyapatite complex (OHC), used as an adjunct in conservative DRF treatment, on muscle strength and ROM. Methods: This was a prospective randomized clinical study. We assessed 31 patients who underwent non-surgical DRF treatment at our center in the years 2024–2025 and were receiving OHC throughout their fracture treatment. K-Grip and K-Push dynamometers were used to measure the maximum and average muscle strength via tests of grip strength, palmar flexion, and dorsal flexion. Wrist ROM was also evaluated. The results were compared with those of the control group (31 patients receiving DRF treatment without OHC) and with the intact limb. Results: The medians of the maximum muscle strength in each test were comparable between the study groups. Both groups showed a higher median average strength in the intact limb than in the treated limb. We observed no intergroup differences in wrist ROM, with ROM parameters lower in the fractured limb than in the intact limb. Conclusions: The additional use of OHC was not associated with statistically significant improvements in functional outcomes. The patients from both groups achieved worse muscle strength and ROM outcomes in the fractured than in the intact limb. We recommend a longer and more intense rehabilitation of patients with DRFs. More studies on this topic are needed in order to unequivocally verify the effects of OHC on functional parameters in fracture patients. Full article

Wearable inertial sensing has considerable potential for process-level analysis of upper-limb function, but further evidence is needed to understand how it can be applied within ecologically structured immersive virtual reality (VR) tasks. Most VR-based functional assessments rely primarily on outcome-level indicators, such as task completion time, success rate, or error count, which may not fully capture how a task is executed. This exploratory study investigated whether wearable IMU signals collected during an immersive VR sushi-making task could support binary detection of a core upper-limb manipulation phase and provide additional information about task execution beyond global performance outcomes. A total of 45 participants contributed usable motion recordings for this study, with five Xsens DOT sensors placed on the hands, forearms, and waist. Three signal modalities were analysed, including acceleration (ACC), gyroscope angular velocity (GYR), and Euler angles. The downstream recognition problem was formulated as a binary classification task (Placing vs. Non-Placing), and a self-supervised learning (SSL) pretrain–fine-tune strategy was evaluated against conventional machine learning and from-scratch deep learning baselines using five subject-wise validation splits. The strongest overall performance was achieved with hand-mounted accelerometer signals, with LeftHand–ACC achieving a Macro-F1 of $0.712\pm 0.128$ and RightHand–ACC achieving $0.679\pm 0.118$. Under both hand-ACC settings, SSL fine-tuning showed higher mean Macro-F1 than the Balanced Random Forest baseline and the same deep architecture trained from scratch. Recognition performance varied substantially across sensor locations, signal modalities, and task segments, with distal upper-limb sensors generally outperforming waist-based configurations. Cross-age analyses further showed that within-cohort and cross-cohort performance did not fully align, indicating sensitivity to age-related distribution shift. Beyond classification, Log Dimensionless Jerk (LDLJ) derived from the Placing action showed a significant positive association with Cognitron motor control time cost ($r=0.636$, $p<0.001$). These findings suggest that wearable IMU sensing can provide preliminary process-level information during immersive VR functional tasks, including task-phase detection, sensing-configuration comparison, cross-cohort generalisation assessment, and exploratory motion-quality analysis. The results should be interpreted as evidence of feasibility rather than as a mature biomechanical or clinical assessment model. Full article

Background and Clinical Significance: Acute compartment syndrome is a rare but limb-threatening emergency in pediatric patients. While most cases follow high-energy trauma or displaced fractures, acute compartment syndrome precipitated by initially underestimated forearm injuries is uncommon and may create a significant diagnostic challenge, particularly in young children who exhibit atypical clinical presentations, such as escalating anxiety and analgesic requirements, rather than classic ischemic signs. Case Presentation: We report the case of a 4-year-old girl who developed severe forearm and hand compartment syndrome following a delayed presentation after a fall from a height of 2–2.5 m onto the left upper extremity. Initial evaluation revealed progressive tense swelling, severe pain with passive stretch, diminished distal perfusion, and radiographic evidence of distal radius-ulna buckle fractures associated with a proximal ulna fracture. Emergent surgical decompression via extensive volar and dorsal fasciotomies revealed markedly elevated compartment pressures. Intraoperatively, deep volar muscle ischemia and necrosis were identified, requiring carpal tunnel release, serial debridements, and complex staged wound management. Multidisciplinary care and ongoing rehabilitation were essential for limb salvage and functional recovery. Conclusions: This case underscores the profound unpredictability of pediatric compartment syndrome and demonstrates that even classically stable, benign fractures can initiate a devastating ischemic cascade. A high index of suspicion, regardless of the injury mechanism, along with early recognition and prompt surgical intervention, is absolutely critical for preventing irreversible myoneural damage and optimizing management outcomes in pediatric patients. Full article

Background/Objectives: The median nerve exhibits clinically relevant anatomical variability, with critical implications for surgical exposure, regional anesthesia, peripheral nerve repair, and diagnostic imaging. Despite extensive descriptive reports, quantitative morphometric analyses incorporating biological sex and donor record population classification remain limited, particularly among Hispanic cadaveric cohorts. Methods: This multi-institutional cadaveric study evaluated median nerve formation and segmental morphometry in 82 anatomical donors, each contributing paired bilateral upper limbs (164 upper limbs total), classified in institutional records as Puerto Rican, Caucasian, or African American. Standardized dissections were performed from the brachial plexus to the distal forearm, and linear measurements were obtained between predefined anatomical landmarks using digital calipers. Results: Mixed-effects modeling was used to evaluate morphometric differences associated with biological sex, donor record population classification, and anatomical location. Male specimens demonstrated localized differences in proximal median nerve formation, including a longer medial cord contribution on the left side. Population group comparisons identified greater measured morphometric distances in the Puerto Rican cohort compared with Caucasian and African American cohorts. Normalized LEH/MEH ratios did not differ between sexes, suggesting that some absolute differences may reflect limb-size scaling rather than proportional shifts in nerve position. Conclusions: These findings provide standardized landmark-based morphometric data and support the value of population-sensitive anatomical reference data for surgical planning and imaging-based interpretations of median nerve morphology. Full article

The use of prosthetic devices can significantly improve the quality of life of individuals with limb amputations. However, existing prosthetic hands face multiple engineering and manufacturing challenges, making them economically inaccessible to a large portion of the population. This study focuses on the design and analysis of a cost-effective prosthetic hand capable of performing five fundamental grasp types: tripod, cylindrical, spherical, lateral, and pinch. The development process began with a biomechanical analysis of the human hand, followed by the derivation of a kinematic model. To ensure anthropomorphic fidelity, finger trajectories were synthesized using a computer vision-based algorithm that captured natural human motion. These trajectories were then mapped to the prosthetic control system. Experimental validation was conducted through rigorous goniometric analysis of the prototype’s execution. The results demonstrated the system’s effectiveness in replicating functional grasps, with a Root Mean Square Error (RMSE) within acceptable thresholds for assistive tasks. While the prototype achieved high motion correspondence, higher deviations were observed in distal joints due to mechanical transmission resistance and spring-return torque requirements. This work provides a scalable framework for tendon-driven prostheses, balancing advanced trajectory synthesis with a robust and accessible mechanical architecture. Full article

Background: The latissimus dorsi free flap is a workhorse for extensive lower-extremity soft tissue defects. Conventionally, the skin paddle is designed according to the anticipated defect and left in place on the muscle as a single composite unit. This report describes an alternative approach in which the skin paddle is secondarily mobilized through subcutaneous undermining and rotated as a separate propeller-type local extension flap on random-pattern vascularization, without a specifically identified perforator—a technique that has not been previously reported. Case Presentation: A 38-year-old male with a high-energy distal lower-extremity defect exposing bone, Achilles tendon, and hardware underwent free latissimus dorsi reconstruction with an empirically designed skin paddle over the constant perforator zone. The skin paddle was subsequently mobilized and rotated as a separate propeller-type extension flap to cover the Achilles region, with additional areas managed using split-thickness skin graft and a reverse soleus flap. Results: The latissimus dorsi flap and skin paddle remained viable, providing stable coverage of the defect. The additional reverse soleus flap achieved durable medial coverage, and the limb was ultimately preserved with satisfactory soft-tissue stability. Conclusion: A random-pattern latissimus dorsi skin paddle designed within the anatomically constant perforator zone can provide a feasible new option offering intraoperative flexibility in complex lower-extremity trauma when perforator mapping is impractical. Full article

The objective of this study was to investigate the impact of localized muscle fatigue (LMF) in the hip, knee, and ankle muscle groups on stair ascent biomechanics, with a focus on identifying compensatory mechanisms following fatigue. Twenty-five participants were fatigued using an isokinetic dynamometer to induce unilateral muscle fatigue in the hip extension, knee extension, and ankle plantarflexion muscles through repetitive isokinetic contractions. We collected stair ascent data before fatigue and after three different fatigue protocols, simultaneously collecting kinematic, kinetic, and electromyographic data. The effects of different muscle fatigue conditions on stair ascent performance were assessed using one-way repeated-measures ANOVA. Key findings revealed that hip fatigue narrowed step width and increased ankle dorsiflexion. Knee fatigue reduced knee extensor moments on the fatigued side and increased hip extension moments bilaterally. Ankle fatigue decreased plantar flexion and increased hip extension moments. Electromyographic data confirmed corresponding shifts in muscle activation. Collectively, the results suggest that localized lower-limb fatigue may alter stair ascent biomechanics in a joint-specific manner. The observed changes in joint moments and muscle activation may reflect a bidirectional pattern of inter-joint compensation, with proximal-to-distal or distal-to-proximal adjustments depending on the fatigued joint. These findings suggest that mechanical and neuromuscular demands may be redistributed across lower-limb joints under acute fatigue conditions; however, given that this study was conducted in healthy young males, the relevance of these findings to stair-related instability or fall risk in more vulnerable populations should be examined in future studies. Full article