Search Results (3,267)

The complex flow behavior of the metal around the stirring tool during welding directly determines the microstructural evolution, defect formation, and mechanical properties of the welded joint, and thus becomes the core physical process affecting welding quality and process stability. In this study, to characterize the three-dimensional material flow behavior of AZ31 magnesium (Mg) alloy during friction stir welding (FSW), conventional metallographic sectioning was adopted as the primary observation method, and copper foil was used as the marker material. The flow trajectories of the materials after welding were investigated via three configurations of the marker material. The results indicate that three typical characteristic zones exist along the vertical direction, which are the shoulder-affected zone (SAZ), the pin-affected zone (PAZ), and the swirl zone from top to bottom. Specifically, the material in the SAZ is dominated by laminar flow; the PAZ exhibits complex mixed-flow characteristics; while the swirl zone shows an obvious rotational flow pattern. Based on the principles of material mechanics and fluid mechanics, a force-flow coupled “simple flow model around a rotating cylinder” was proposed, which defines three flow modes corresponding to the different characteristic zones within the weld. Full article

Background: Corticosteroid injections provide short-term relief for chronic subacromial bursitis but are associated with high recurrence rates. This study investigates the efficacy of a mobile health-supported home-based resistance exercise program compared with exercise education in patients with chronic recurrent subacromial bursitis after ultrasound-guided corticosteroid injections. Methods: Participants with chronic subacromial bursitis were assigned via computer-generated block randomization to either an intervention group receiving ultrasound-guided corticosteroid injections followed by a 12-week home-based exercise program (50 min strengthening and resistance/session, 5 days per week) supported via instant messaging applications, or a control group receiving the same injection followed by printed educational materials covering the same exercise protocol. Shoulder Pain and Disability Index (SPADI) scores, Visual Analog Scale (VAS) pain scores and active pain-free range of motion (ROM) were evaluated by a blinded assessor at weeks 4 and 12. Between-group comparisons were analyzed using two-way ANOVA after confirming normality and homoscedasticity. Results: Fifty-three patients (mean age: 55.6 ± 10.5 years; 47.2% female) were randomized to the intervention (n = 27) or control (n = 26) groups. Significant interaction effects were identified for SPADI (p = 0.040) and ROM (abduction: p = 0.036/ flexion: p = 0.032). Post hoc analysis revealed that the intervention group exhibited a significantly greater reduction in SPADI scores (p = 0.007, d = 0.72) and greater increase in abduction ROM (p = 0.004, d = 0.84) at 12 weeks; both gains surpassed the MCID. Conclusions: A mobile health-supported home-based resistance exercise program can significantly extend the benefits of corticosteroid injections in patients with chronic subacromial bursitis. Trial Registration: NCT06220643, registered 14 December 2023. Full article

Background: Breaststroke performance in young swimmers is influenced by a complex interaction of anthropometric, physiological, and technical factors. However, existing studies predominantly focus on pre-selected or elite youth swimmers, limiting insight into performance development in non-elite populations without early selection bias. Purpose: This study aimed to identify key predictors of 50-m breaststroke performance and to examine longitudinal changes in selected characteristics in pre-adolescent, non-elite female swimmers. Methods: Fourteen female swimmers (baseline biological age: 10.52 ± 0.37 years) who entered swimming training without prior anthropometric or physiological selection were followed over three consecutive years. Measurements were collected at six time points and included anthropometric dimensions, body composition, aerobic and anaerobic capacity, respiratory volumes, and 50-m breaststroke performance. This investigation was a prospective longitudinal cohort study. Data were analysed using generalised estimating equations. Results: The correlation-filtered model explained 76% of the variance in 50-m breaststroke time. Chest depth (B = −0.16, p = 0.03), foot length (B = −0.17, p = 0.04), foot width (B = 0.30, p < 0.001), and shoulder width (B = −0.07, p = 0.04) emerged as significant anthropometric predictors. Maximal oxygen uptake also showed a significant association with performance (B = −0.33, p = 0.02). Conclusions: In pre-adolescent, non-elite female swimmers, selected anthropometric characteristics—particularly trunk dimensions and foot morphology—are associated with short-distance breaststroke performance. Aerobic capacity appears to play an indirect, supportive role. These findings highlight the importance of longitudinal monitoring without early selection and support a development-oriented approach to youth swimming training. Full article

Background and Objectives: Dentofacial asymmetries are common in patients with malocclusions, while mild body postural asymmetries are frequently reported in otherwise healthy individuals. However, their interrelationship remains insufficiently investigated in adults without diagnosed spinal disorders. This study aimed to evaluate the association between dentofacial and body postural asymmetries in adults with malocclusions. Materials and Methods: A clinical cross-sectional observational study was conducted on 102 adults (18–45 years) with malocclusions and no spinal pathology. Standardized clinical morphometric examinations assessed dentofacial asymmetries (horizontal and vertical planes), dental parameters (dental midlines deviation and occlusal plane inclination), and body postural asymmetries (head, shoulder, trunk, pelvic, and lower limb alignment). Asymmetries were recorded using predefined clinical thresholds. Statistical analyses included the Wilcoxon signed-rank test, Pearson chi-square test, and Spearman’s rank correlation coefficient. Results: Dentofacial asymmetries were identified in both planes and occurred more frequently on the left side. Horizontal facial asymmetries were most common at the cheek (74.5%), nostril (66.7%), and mandibular angle levels (57.9%), and were influenced by sex, age, facial growth pattern, and facial profile (p ≤ 0.05). Mandibular dental midline asymmetry was present in 55.8% of patients. Body postural asymmetries were also frequent, particularly unilateral (60.8%) or anterior (55.9%) head inclination and shoulder asymmetries (54.9%), with a predominance on the left side and associations with age, body mass index, and postural attitude (p ≤ 0.05). Correlations were identified among facial asymmetries and among body postural asymmetries (p ≤ 0.01), indicating a bilateral distribution pattern. Additionally, right-sided facial asymmetries showed significant positive associations with right-sided body postural asymmetries (ρ = 0.197–0.229; p ≤ 0.05). Conclusions: Dentofacial and body postural asymmetries have been identified in adults with malocclusions and presented side-specific associations regarding the patterns of asymmetry. Full article

Continuous monitoring of pathological motor features is vital for post-stroke rehabilitation but remains challenged by power reliance and low sensitivity of wearable sensors. Here, we develop a high-sensitivity, self-powered breathable nanogenerator (BN-TENG) utilizing fish-scale-derived biological hydroxyapatite/carbon (Bio-HAp/C) fillers within electrospun polyvinylidene fluoride (PVDF) nanofibers. The Bio-HAp/C enhances electron-trapping capability, while a high-resilience ethylene-vinyl acetate (EVA) spacer optimizes contact-separation dynamics. The BN-TENG achieves a superior sensitivity of 16.28 V·N⁻¹ and remarkable stability over 10,000 cycles. By implementing a multi-node sensing strategy, the sensor successfully captures complex hemiplegic patterns, including compensatory shoulder hiking, distal muscle spasticity, and postural asymmetry. By resolving subtle micro-vibrations missed by traditional electronics, this work provides a sustainable, autonomous interface for characterizing pathological motor features and assessing rehabilitation progress in hemiplegic patients. Full article

Background: Wrist–forearm orthoses used during self-feeding may alter scapular and shoulder mechanics and increase proximal load, but this has not been quantified. Methods: Seventeen right-hand-dominant young adults performed a spoon-feeding task under free and restricted conditions. A thermoplastic wrist–forearm orthosis positioned the wrist at approximately 30° dorsiflexion at rest and was intended to constrain wrist motion during the task without rigidly immobilizing forearm pronation–supination. Three-dimensional kinematics (scapula, shoulder, trunk, and distal joints) were recorded using inertial sensors, and surface electromyography was obtained from the upper trapezius, middle deltoid, and biceps brachii. Maximum joint angles and mean %MVC over the feeding cycle were compared between conditions (α = 0.05). Results: The restriction condition resulted in a more anteriorly tilted and downwardly rotated scapular posture, greater shoulder abduction and external rotation, and increased thoracic flexion, whereas maximum distal joint angles did not differ, suggesting a functional distal constraint rather than rigid immobilization. Middle deltoid and biceps brachii activities increased significantly, with a nonsignificant trend toward higher upper trapezius activation. Conclusions: In healthy young adults, limited wrist motion and forearm rotation during spoon-feeding were associated with altered proximal coordination, including scapular, shoulder/trunk, and proximal muscle changes. Full article

Background: Informal sewing workers are widely exposed to ergonomic and workload-related risks but remain largely excluded from formal occupational health protection, particularly in low- and middle-income countries. This study evaluated integrated physical and mental workload risks associated with WMSDs among informal sewing workers to develop contextually feasible preventive guidelines based on the Hierarchy of Ergonomic Control. Methods: A mixed-methods study was conducted among 150 informal sewing workers in Ubon Ratchathani Province, Thailand. Quantitative data were collected using a structured questionnaire, the Rapid Upper Limb Assessment (RULA), the Nordic Musculoskeletal Questionnaire (NMQ), and the NASA Task Load Index (NASA-TLX). Associations between sociodemographic characteristics, ergonomic risks, and WMSDs were analyzed using chi-square tests and correlation analysis. Qualitative data were obtained through a focus group discussion with key stakeholders to develop ergonomic control strategies guided by the HEC framework. Results: The majority of participants were female and middle-aged, with widespread exposure to high-risk ergonomic conditions, including prolonged sitting, repetitive tasks, and awkward postures. A high prevalence of WMSDs was observed, particularly in the neck, shoulders, and back. Younger workers and those with lower educational attainment experienced significantly higher ergonomic risk exposure and WMSD prevalence. NASA-TLX results indicated that physical demand and performance pressure were the main contributors to overall workload. Application of the HEC framework showed that elimination and substitution controls were the most effective strategies for reducing ergonomic risks, followed by engineering controls, while administrative measures and personal protective equipment were less effective. Conclusions: Informal sewing workers face substantial ergonomic and mental workload risks that contribute to a high burden of WMSDs. Prioritizing higher-order ergonomic controls, integrating workload management, and implementing community-based ergonomic interventions are essential to improving occupational health and reducing inequities among informal workers. Full article

This review examines rotator cuff and shoulder complex dysfunction through an evolutionary framework and aims to translate these concepts into practical resistance training applications for strength and conditioning and rehabilitation professionals. Comparative anatomy and functional biomechanics of the human and non-human primate shoulder complexes are reviewed to illustrate how evolutionary pressures shaped an upper extremity system optimized for stability and force transmission under closed kinetic chain (CKC) loads. In contrast, many contemporary resistance training practices emphasize high-load, open kinetic chain (OKC) exercises that may impose elevated soft tissue strain and shear forces while potentially diminishing the engagement of the scapulothoracic and trunk stabilization mechanisms evolved to protect the shoulder complex. This proposed evolutionary mismatch may contribute to the high prevalence of shoulder dysfunction observed in the modern human population. Rotator cuff pathology arises through a combination of mechanisms, including, but not limited to, age-related tendon degradation, anatomical variations, mechanical overload factors, as well as systemic comorbidities. The contribution of habitual loading patterns to this multifactorial etiology has been considered in the literature, but this review advances a novel evolutionary mismatch hypothesis as one framework through which a primary biomechanical cause of overuse shoulder pathology may be examined. Applications of these concepts to exercise program design are presented. Specifically, training modifications consider moderately loaded CKC exercises performed at higher volumes with an emphasis on movement velocity and power generation. Incorporating moderate-load, high-volume, high-velocity CKC exercises may preserve rotator cuff integrity and optimize upper extremity function across the lifespan while potentially reducing the loading demands and associated mechanical stress that, under high-load or high-volume conditions, traditional OKC training models place on the shoulder and therefore, challenge the shoulder’s evolved structural tolerance. Full article

Background and Clinical Significance: Scoliosis prevalence in patients with ataxia telangiectasia (AT) is higher than in the general population. Scoliosis monitoring is traditionally performed using X-rays, but radiographic imaging is contraindicated in AT patients due to radiation sensitivity. Current guidelines suggest a diagnostic radiograph with subsequent Magnetic Resonance Imaging (MRI). In this report, we (1) evaluated the feasibility of using surface topography (ST) to observe 3D spine curvature trends in a long-term follow-up of a patient with scoliosis and AT, and (2) developed a novel paradigm for monitoring scoliosis in AT patients. Case presentation: A female patient (11 years old) with AT and scoliosis was monitored using ST in five visits over four years. Between subsequent visits, her ST measurements included average changes in thoracic scoliotic angle of 5.5° ± 4.9°, thoracolumbar scoliotic angle of 7.8° ± 5.5°, thoracic axial surface rotation (ASR) of 8.0° ± 8.5°, thoracolumbar ASR of 7.0° ± 4.5°, thoracic apical deviation of 6 mm (only measured in two visits), thoracolumbar apical deviation of 10 mm ± 2.4 mm, pelvic obliquity of 5.8 mm ± 3.9 mm, shoulder obliquity of 20 mm (only measured in two visits), coronal imbalance of 11.8 mm ± 9.7 mm, and kyphotic angle of 5.5° ± 5.4°. ST effectively monitored curve patterns throughout the 4-year treatment period, enabling informed treatment decisions by the provider, patient, and family. We also developed a novel paradigm combining diagnostic MRI with serial ST imaging every 6–12 months to monitor curve progression with supplemental MRI as needed. Conclusions: Our novel ST paradigm provides a feasible method for monitoring 3D scoliosis progression in AT patients while avoiding unnecessary radiographic imaging. Full article

Background/Objectives: Rotator cuff repair (RCR) is a common orthopedic procedure, with healing outcomes strongly influenced by patient-specific factors such as tissue quality, tear characteristics, and biological healing potential. Bioinductive collagen implants have shown great results in enhancing tendon healing and reducing retear rate. This study aimed to evaluate the clinical and imaging outcomes of RCR augmented with a xeno-derived collagen membrane over 24 months and to assess complications or implant failures. Methods: Patients underwent arthroscopic RCR using anchors (single or double-row) with additional xeno-derived matrix augmentation. The study included patients older than 40 years with full-thickness supraspinatus and/or infraspinatus tendon tears (DeOrio–Cofield grade 3–4) who were candidates for arthroscopic rotator cuff repair and provided informed consent. Clinical outcomes were assessed using the Constant–Murley Score (CMS), Disabilities of the Arm, Shoulder and Hand score (DASH), and Visual Analogue Score (VAS) at baseline, 3, 6, 12, and 24 months. MRI was performed preoperatively and at 24 months to assess tendon thickness. Results: All scores improved significantly. CMS increased from 16.3 ± 4.1 to 82.9 ± 5.8, VAS decreased from 7.8 ± 1.0 to 1.5 ± 0.8, and DASH improved from 70.3 ± 6.4 to 12.4 ± 4.5 (p < 0.05). Tendon thickness in the supraspinatus (T3) increased from 4.2 ± 0.9 mm to 6.8 ± 1.2 mm (p < 0.05). Retear rate was 7.55%, with no major complications. Conclusions: The bioinductive collagen implant showed notable results in improving tendon thickness, healing, and excellent clinical outcomes in RCR, without membrane-related complications. The study was designed as a prospective single-arm case series without a control group and that was the main limitation; The absence of adverse reactions in this cohort further supports the favorable safety profile of this implant in the present study population. Full article

Background: Work-related musculoskeletal disorders (WMSDs) are common among surgeons. The objective was to study how economic, demographic, and quality-of-life indicators influence the WMSD prevalence among European surgeons. Methods: A systematic review and meta-analysis was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Three open databases were scanned without a date limit to extract the overall WMSD prevalence and by body area. Results: Among the 11,814 articles, 25 were included, with a total of 5174 surgeons. The overall prevalence was pooled at 75.8% (95% CI: 68.6–83.1%). The most affected areas were lower back (52.1%, 95% CI: 43.1–61.0%), neck (51.2%, 95% CI: 43.7–58.9%), shoulder (43.1%, 95% CI: 36.4–49.8%) and upper back (34.2%, 95% CI: 24.2–44.1%). Surgeons aged over 45 with more than 10 years’ experience had a higher prevalence of WMSDs in the neck, hip, upper and lower back. The overall and lower back prevalence was higher among surgeons in countries where the surgery-by-surgeon ratio was greater than 125. A negative correlation was observed between the Human Development Index and the lower back prevalence. Conclusions: Further research is needed to strengthen ergonomics programs, knowledge, and organizational work strategies to effectively reduce WMSD prevalence among European surgeons. Full article

Objectives: Arthroscopic surgery requires complex visuospatial coordination and psychomotor skills, which are traditionally acquired through mentorship and cadaveric training. High-fidelity simulators are effective but often costly and inaccessible. This study evaluates the technical effectiveness of a novel home-based 3D-printed arthroscopic simulator (“Arthrozero”) for improving basic arthroscopic skills among orthopedic residents. Methods: Thirty-three orthopedic residents (25–36 years) from two Italian university centers were randomized into three groups: ZERO (Arthrozero training), ARTHRO (real arthroscope training), and CONTROL (theoretical session). Training was performed on a FAST-like workstation through four progressively complex tasks. Performance metrics included task completion time, number of looks down, and skill progression during a final Shoulder Challenge (SHO-CHA) assessment. A web-based Likert questionnaire evaluated participant satisfaction and perceived educational value. Results: Both ZERO and ARTHRO groups demonstrated significant improvement across training sessions (p < 0.05) for all tasks, while the CONTROL group showed minimal gains. In the SHO-CHA assessment, mean completion times were 394.1 ± 140.7 s (ZERO), 456.1 ± 123.2 s (ARTHRO), and 745.5 ± 190.7 s (CONTROL) (p < 0.01). No significant difference was observed between ZERO and ARTHRO groups (p = 0.276). Conclusions: The home-based Arthrozero simulator demonstrated improvements in basic arthroscopic skill performance, suggesting that it may represent an accessible training tool to support early arthroscopic skill acquisition alongside traditional training methods. Full article

(1) Background: The “Bider marking” on the shoulder of the Dun Mongolian horse represents a unique pigmentation pattern, the molecular formation mechanism of which remains incompletely understood. This study investigates the differential expression and protein localization of pigment-related genes—specifically the core transcription factor MITF, as well as EDN3, SLC7A11, and WNT3A—in the skin. The analysis focuses on three distinct regions: the dark-colored area of the ‘Bider marking’ shoulder (BIDC), the light-colored area of the ‘Bider marking’ shoulder (BILC), and the non-Bider-marked shoulder area (NBIS). The aim is to clarify their correlation with the formation of this distinctive pigmentation pattern. (2) Methods: Skin tissue samples from both the “Bider marking” and non-Bider-marked shoulder regions were collected (n ≥ 3). The mRNA expression levels were quantified using RT-qPCR, protein levels were analyzed through Western blotting, and protein localization was assessed via immunohistochemistry and immunofluorescence. (3) Results: Compared to the NBIS group, both the BIDC and BILC groups exhibited significantly elevated protein expression of MITF and WNT3A. Further immunofluorescence showed that the distribution of MITF protein exhibits regional specificity in the epidermis and hair follicles. In the BIDC region, the protein is localized specifically to the stratum corneum of the epidermis, the dermal papilla, and the outer root sheath of hair follicles. In contrast, the mRNA and protein expression levels of SLC7A11 and EDN3 did not display consistent patterns among the three groups, and no specific differences were observed in tissue localization. (4) Conclusions: The findings show that the specific pigmentation in dark “Bider marking” regions is closely linked to the upregulated protein levels and unique spatial patterns of MITF and WNT3A; SLC7A11 and EDN3 may not be primary regulators of this trait. Full article

Background and Objectives: It is crucial to determine physical findings and outcome measures that affect functional status of the patients, and the impact levels of these parameters on patients. Therefore, the aim of this study was to investigate the determinant and predictive effect of pain levels, shoulder range of motion (ROM) values, disability and health-related quality of life factors on functional status in individuals with partial-thickness rotator cuff tears (PRCT). Materials and Methods: Firstly, the functional status of 45 patients (mean age: 50.78 ± 5.28 years; 29 female) with PRCT, then activity and night pain levels with Numeric Pain Rating Scale, active flexion, abduction and external rotation of the shoulder ROM values with goniometer, disability level with Quick Disabilities of Arm, Shoulder & Hand Questionnaire, and health-related quality of life levels with Short Form-12 were evaluated and recorded. Results: It was detected that all determinants whose effect on functionality was evaluated with a multiple regression model explained 76% of the variance, and this effect level was statistically significant (R square = 0.760, adjusted R square = 0.707, F = 14.272, p < 0.001). Detailed evaluation showed that flexion and external rotation ROM values (respectively; β = 0.54, p < 0.001; β = 0.38, p = 0.001) and disability level (β = 0.44, p < 0.001) had statistically significant determinant effects on functional status. No statistically significant results which could be correlated with functional status were found for activity and night pain, abduction ROM value, and health-related quality of life domains (p > 0.05). Conclusions: Shoulder flexion and external rotation ROMs and disability level were found to have a predictive effect on the functional status in individuals with PRCT. It is noteworthy that more subjective and patient-reported findings and outcome measures such as pain and health-related quality of life had no predictive effect on functionality. By determining the level of these effects, results were reached that can shed light on the literature by guiding the development of reliable assessment algorithms. Full article

Dermatofibrosarcoma protuberans (DFSP) is a rare tumor presenting as a slow-growing, plaque-like or multinodular, brownish lesion on the trunk in adult patients. Diagnosis is established by histological examination and surgical excision is the primary treatment. Typically, DFSP has an indolent course and local spread. In the present work, we describe the clinical–histologic features, surgical treatment and follow-up of a case of DFSP in a patient living with HIV infection (PLWH). A 40-year-old man was referred to us with confluent lesions on the left shoulder, present for about 3 years. His medical history was positive for HIV-1 infection, for which he was taking antiretroviral therapy. Microscopic examination showed dermal and hypodermic proliferation of spindle cells in a storiform pattern, confirming the clinical diagnosis of DFSP. A wide excision was performed with 3 cm clinically healthy tissue margins, and the defect was repaired using an artificial bilaminar dermal matrix. The histological examination revealed tumor-free margins, and a split-thickness skin graft was harvested from the same arm. After 10 months, the patient was free from the disease. As observed with other skin cancers, DFSP may have a higher incidence and greater aggressiveness in immunosuppressed than in immunocompetent patients. DFSP has been reported only twice in PLWH. Our case constitutes a third report, adding to the evidence that there may be an over-representation of this cancer in immunosuppressed individuals. Full article