Search Results (632)

Background and Objectives: Comparisons of swallowing physiology between coronavirus disease 2019 (COVID-19) pneumonia and clinically diagnosed aspiration pneumonia (AP) have largely relied on ordinal scales, leaving etiology-specific biomechanical profiles unclear. We quantitatively compared videofluoroscopic swallowing study (VFSS) measures of pharyngeal residue and clearance mechanics to identify differential dysphagia phenotypes. Materials and Methods: This single-center retrospective cohort study included 50 adult inpatients with pneumonia (COVID-19, n = 25; AP, n = 25) who underwent VFSS for suspected dysphagia. COVID-19 pneumonia was laboratory-confirmed, and AP was clinically diagnosed after negative tests for severe acute respiratory syndrome coronavirus 2. Blinded ImageJ analysis examined the first standardized semisolid yogurt swallow (International Dysphagia Diet Standardisation Initiative level 4). Primary outcomes were Normalized Residue Ratio Scale values for the valleculae (NRRSv) and piriform sinuses (NRRSp); secondary outcomes were upper esophageal sphincter (UES) opening width and epiglottic rotation angle. Penetration–Aspiration Scale (PAS) score, hyoid displacement, and pharyngeal transit time were exploratory. Results: Baseline characteristics were comparable. COVID-19 pneumonia showed higher NRRSv (0.20 [0.12–0.56] vs. 0.13 [0.00–0.20]; p = 0.01). NRRSp was numerically higher but not statistically significant (0.12 [0.00–0.43] vs. 0.00 [0.00–0.17]; p = 0.07). COVID-19 pneumonia also showed smaller UES opening width (5.08 ± 2.48 vs. 6.50 ± 2.01 mm; p = 0.03) and reduced epiglottic rotation angle (66.0 [29.0–80.8] vs. 93.4 [74.2–100.4] degrees; p = 0.04). No statistically significant between-group difference was detected in PAS-defined airway invasion severity on the standardized semisolid task. Conclusions: These findings suggest an efficiency-predominant dysphagia phenotype in COVID-19 pneumonia, characterized by greater vallecular residue and restrictive clearance-related mechanics on a standardized semisolid task. The results indicate that PAS-defined safety metrics alone may underestimate residue-related dysphagia burden in this population. Full article

Low back pain (LBP) is a major global health problem and can result in a variety of movement impairments. Advances in smart technology have enabled the collection of novel streams of movement data, and machine learning (ML) methods have been increasingly used for data analysis. However, many existing technologies remain expensive and unsuitable for widespread clinical use, and ML approaches have largely focused on distinguishing people with LBP from healthy controls rather than identifying meaningful subgroups within the LBP population. Motion Tape (MT) is a recently developed wearable strain sensor that translates skin deformation from underlying movement and muscle engagement into electrical signals. In this exploratory study involving 10 participants with LBP, we demonstrate that MT data from six sensors applied on the lower back capture rich movement information capable of characterizing movement patterns among participants with LBP. We propose a feature engineering approach based on biomechanical features as well as time-series causal discovery applied to multivariate sensor time-series data to extract directed inter-segment coordination patterns. We further develop an exploratory subgroup discovery pipeline by aggregating clustering coassociation information across diverse movement tasks. Our causal coordination features show promising discriminative information across several movement types, capturing aspects of motor control not reflected in amplitude-based or embedding-based features alone, such as asymmetries and movement restrictions. Preliminary ensemble clustering analysis indicates three potential LBP subgroups distinguished by biomechanical and inter-segment coordination patterns, which may reflect varied strategies under different movement demands. We investigate the differences in clinical characteristics among these LBP subgroups. We show that time-series foundation models are not well suited for LBP subgrouping due to their uninterpretability, which is improved in our feature engineering pipeline. This framework could reveal additional subgroups with larger cohorts and may generalize to other sensor modalities. Full article

Background/Objectives: This study aimed to evaluate the biomechanical characteristics of the cornea to assess their diagnostic accuracy in distinguishing normal eyes from those suspected keratoconus eyes. Methods: In this cross-sectional study, corneal elevation and curvature radius were measured in 217 participants using Pentacam. Average values were obtained based on the best-fit sphere (BFS) and the enhanced best-fit sphere (EBFS). The biomechanical characteristics of the cornea were assessed using the Corvis ST device. Receiver operating characteristic curve analysis was performed to determine the diagnostic accuracy. Results: The radii of the BFS in the anterior and posterior corneas were significantly larger in the normal group compared to the suspected keratoconus group. Conversely, EBFS elevation values in both the anterior and posterior corneas were lower in the normal group. The velocity at which the cornea was first flattened had the highest diagnostic accuracy for identifying suspected keratoconus. Conclusions: Eyes with suspected keratoconus had a significantly smaller corneal radius on both the anterior and posterior surfaces compared with normal eyes. In addition, due to the increased deformability and reduced resistance to a given force, these parameters serve as valuable biometric indicators for distinguishing suspect eyes from normal eyes. Full article

Rowing performance depends on boat velocity and technical efficiency, varying across boat classes. We quantified intracycle velocity variation (IVV) during 2000 m competitions using a GPS- and accelerometry-based monitoring and examined its relationship with biomechanical variables. Forty-nine races were recorded during three national regattas, involving 206 experienced rowers (72 females). Boats were classified by discipline (sweep vs. sculling) and length (short vs. long). Boat velocity and position were recorded using GPS (15 Hz) and accelerometry (100 Hz). Sculling boats demonstrated higher average velocity and lower IVV than sweep boats (p ≤ 0.05), possibly due to reduced lateral asymmetries. Long boats (quadruple scull, four and eight) reached significantly higher maximum, average, and minimum velocities than short boats (single scull, double scull, and pair) (all p ≤ 0.05), as well as greater technical index and distance per cycle. Correlation analysis identified large associations (r ≥ 0.5): in long boats, maximum and minimum velocity (r = 0.79) and cycle rate with distance per cycle (r = −0.50), whereas in short boats, average velocity was associated with minimum velocity (r = 0.76), technical index (r = 0.84) and distance per cycle (r = 0.64). In conclusion, IVV appears to be influenced by boat class and crew characteristics, representing a relevant sensor-derived indicator for monitoring technical efficiency in competitive rowing. Full article

Background: Anterior cruciate ligament (ACL) injury is one of the most common injuries among athletes and demonstrates significant sex-based differences in incidence, with a higher documented risk in females. Various anatomical, biomechanical, neuromuscular, and hormonal factors have been proposed to explain this disparity; however, the available evidence remains inconclusive due to methodological heterogeneity across studies, variability in outcome measures, and inconsistencies in the assessment of hormonal and biomechanical variables. Objective: To map and synthesize the scientific evidence regarding risk factors associated with ACL injury during sports activity, incorporating a sex-specific analytical perspective. Methods: A scoping review was conducted following the methodological framework proposed by Arksey and O’Malley, the Joanna Briggs Institute guidelines, and the PRISMA Extension for Scoping Reviews (PRISMA-ScR). A systematic search was performed in PubMed and Scopus through September 2025. Observational and experimental studies assessing ACL injury risk factors and analyzing sex-based differences were included. Findings were synthesized using a descriptive and narrative approach. Results: Nineteen studies were included. Biomechanical and neuromuscular factors were the most frequently investigated domains among the included studies (68.4%), followed by hormonal (42%) and anatomical factors (36.8%). These percentages reflect the distribution of research focus across the literature rather than the relative strength or importance of each risk factor. In females, injury risk was primarily associated with high-risk biomechanical patterns, cyclical hormonal variations, and specific anatomical characteristics. In males, risk factors were mainly related to muscular weakness, joint laxity, and structural ligament characteristics. Conclusions: ACL injury risk in athletes appears to be influenced by multiple interacting intrinsic and extrinsic factors. The available evidence suggests that sex-related differences may exist in the contribution of biomechanical, anatomical, hormonal, and neuromuscular factors; however, these relationships are multifactorial and should be interpreted cautiously given the heterogeneity of the included studies. Full article

(1) Background: Mandibular condylar fractures continue to be a subject of debate, traditionally framed as a choice between open and conservative management. However, this binary approach fails to adequately account for fracture-level anatomy, Temporomandibular joint (TMJ) involvement, and functional outcomes. (2) Purpose: To present an imaging-guided, fracture-level-based algorithm that integrates radiologic evaluation, surgical approach selection, fixation biomechanics, and functional rehabilitation. (3) Review Strategy: This invited review combines current evidence with a 13-year institutional experience involving 495 joints. High-resolution Computed Tomography (CT) Imaging was used to assess fracture morphology, displacement, and ramal height, while Magnetic Resonance Imaging (MRI) was selectively employed in intracapsular fractures to evaluate disc–condyle relationships when intra-articular involvement was suspected. Management decisions, including surgical approach and fixation strategy, were guided by an institutional algorithm tailored to fracture characteristics. (4) Results: Implementation of this approach yielded consistent and predictable outcomes. Mouth opening improved from approximately 18.77 mm preoperatively to 40 mm at 6 months. Lateral excursions became symmetrical (~9.6 mm), occlusion was restored in all patients, and bite force returned to near-physiological levels. Pain scores showed near complete resolution within 1 month. Postoperative morbidity remained low, with predominantly transient facial nerve weakness. (5) Conclusions: This imaging-guided, algorithmic framework provides reproducible functional outcomes and signifies a shift toward structured, anatomically driven management of condylar fractures. Full article

This exploratory study compares the Froude efficiency (η_F), intra-cyclic speed fluctuation (ICSF) and other performance determinants between two freestyle swimming techniques: double-arm backstroke and front crawl, and then demonstrates how Para swimmers with hypertonia differ from non-disabled swimmers when performing double-arm backstroke. Three-dimensional motion analysis was undertaken on three Para swimmers with hypertonia (sport classes 3–4) and eight non-disabled swimmers performing a simulated double-arm backstroke with lower limbs immobile. The non-disabled group also completed front crawl trials. Swimming speed, stroke frequency, stroke length and η_F were significantly greater, and ICSF significantly lower, during front crawl than during double-arm backstroke in non-disabled swimmers. Para swimmers’ double-arm backstroke speed was 45–52% that of the non-disabled group; their stroke length was 58–69% shorter and stroke frequency 26–53% higher. Non-disabled swimmers demonstrated higher peak elbow extension velocity during the push phase than Para swimmers (6.36 ± 1.26 rad∙s⁻¹ vs. 1.50–1.81 rad∙s⁻¹) and their η_F was approximately double the Para swimmers’ (0.33 ± 0.02 vs. 0.14–0.18). Para swimmers displayed poorer body alignment than the non-disabled group; ICSF did not differ between groups. Double-arm backstroke is slower and less efficient than front crawl. Hypertonia may reduce the efficiency of double-arm backstroke by diminishing propulsive movements and worsening body orientation. Full article

Background: High-heeled footwear is widely used by women, yet its systemic influence on spatiotemporal gait parameters, pelvic kinematics, and propulsion across a range of heel heights remains incompletely characterised. This study aimed to quantify gait changes across four footwear conditions and assess the contribution of anthropometric characteristics to observed gait variability. Methods: A within-subject repeated-measures study was conducted with 75 healthy young adult women (mean age 24.3 years, BMI 21.3 kg/m²) assessed barefoot, in ballerina flats, 8 cm heels, and 12 cm heels using the G-WALK inertial measurement system (BTS Bioengineering). Thirty gait parameters were analysed using the Friedman test with Bonferroni-corrected Wilcoxon post hoc comparisons (α_adj = 0.0083), Spearman rank correlations, multiple linear regression, and Kruskal–Wallis tertile analysis. Results: Footwear significantly affected 22 of 30 parameters. Walking speed was higher in all shod conditions than barefoot (up to +9.2%), driven entirely by stride elongation with cadence unchanged, indicating a general effect of footwear rather than heel elevation specifically. Stride length peaked at 8 cm heel (+8.9% vs. barefoot) and declined at 12 cm. Gait symmetry decreased progressively with heel height. Ballerina shoes produced a distinctively dynamic temporal profile—shortest stance duration, lowest double support, and highest single support time—significantly different from both barefoot and heeled conditions. The propulsion index increased height-dependently with heel height, rising 23.3% from barefoot (8.20) to 12 cm heel (10.11; p < 0.001). Pelvic obliquity symmetry was disrupted at 12 cm heel, while tilt symmetry was unaffected. Anthropometric analysis identified 110/600 significant Spearman correlations (23 surviving Benjamini–Hochberg FDR correction) and 29/120 significant regression models (14 surviving FDR); age, body weight, and shoe size were the most consistent predictors, most reliably in the barefoot condition. Conclusions: Heel height exerts condition-specific effects on gait biomechanics. Ballerina shoes produce a gait pattern distinct from both barefoot and heeled walking. Propulsion demand increases height dependently with heel elevation. Because participants walked in their own footwear, the observed effects reflect the combined characteristics of each shoe type rather than heel elevation in isolation. Anthropometric characteristics—particularly age, body weight, and shoe size—are modestly associated with footwear–gait responses and may inform future biomechanical research, although clinical application requires confirmation in standardised-footwear studies and clinical populations. Full article

Background/Objectives: Changes in the mechanical behavior of orthodontic archwires during clinical use are not fully understood, particularly when different bracket systems are employed. Self-ligating (SL) brackets have gained considerable popularity in orthodontic practice in recent years, largely due to claims of improved treatment efficiency and biomechanical performance. Nevertheless, current evidence has not consistently demonstrated statistically significant differences between conventional ligation (CL) brackets and SL systems. The aim of this study was to evaluate changes in the mechanical properties and degradation over time of nickel-titanium (NiTi) archwires after clinical use in orthodontic treatments performed with CL and SL brackets. Methods: A comparative study was conducted using archwires retrieved from orthodontic patients. Round 0.014-inch NiTi wires (GC Orthodontics America Inc., IL, USA) were analyzed. The archwires were used in 60 patients treated with either CL or SL appliances and evaluated at four time points: before clinical use (T0), and after 1 month (T1), 2 months (T2), and 3 months (T3) of intraoral service. Mechanical testing was performed according to ISO 15841:2014 + Amd. 1:2020 using a three-point bending test with a universal testing machine (Z005 Test Control II Universal Testing Machine, Zwick Roell, Kennesaw, GA, USA). The variables analyzed included the mean force delivered by the archwires at deflections of 3 mm (F3), 2 mm (F2), 1 mm (F1), and 0.5 mm (F0.5), as well as the slope of the superelastic plateau at 2 mm, 1 mm, and 0.5 mm. The static and dynamic friction coefficients, as well as the friction forces associated with the wires and the two types of brackets, were determined using a modified MTS-Bionix servo-hydraulic testing machine. The tests were conducted at 37 °C in a saline environment. Results: Both groups showed changes in the superelastic behavior of NiTi archwires. Alterations increased with longer intraoral exposure. In the SL group, significant modifications were already observed after one month of clinical use, with a reduction in the force delivered and a loss of superelastic characteristics. These changes remained relatively stable thereafter, with no statistically significant differences during the following months. In contrast, the CL group showed a progressive reduction in force delivery and superelasticity over time. This is due to the difference in friction between the wire and the CL bracket compared to the SL bracket, which results in greater force transfer for tooth movement. Conclusions: Overall, differences in the mechanical behavior of archwires between CL and SL systems were observed during the initial stages of clinical use. However, these differences diminished over time, and no significant differences were detected after three months. Considering the progressive degradation of mechanical properties, the reuse of archwires that have remained intraorally for more than three months may not be advisable. Full article

Using the finite element analysis software ANSYS (version 2020), we investigated the variation trends in the resonant frequencies of the eyeball, as well as the stress and strain distributions in the optic nerve under different intraocular pressures. To better understand the mechanical and physical characteristics of the eyeball, the reliability and accuracy of ophthalmic research were enhanced. A total of six 3D eyeball models were constructed using SolidWorks (version 2023), including one porcine eyeball model and five human eyeball models with axial lengths of 22, 24, 26, 28, and 30 mm. These axial lengths correspond respectively to hyperopia, emmetropia, and myopia of approximately −6.00, −12.00, and −18.00 diopter, representing different refractive states of the human eye. The models were imported into ANSYS, where the Harmonic Response and Modal Analysis modules were applied to determine the resonant and natural frequencies, and to analyze their trends with respect to axial length variation. The simulation results revealed that, in the modal analysis, the natural frequency decreased with increasing axial length, indicating that longer eyes (more myopic) are more susceptible to lower-frequency vibrations. Despite the frequency differences, the mode shapes under identical modal orders remained highly similar across all models, demonstrating consistent vibrational behavior among eyes of different axial lengths. These findings contribute valuable biomechanical insights into the vibrational characteristics of the eyeball and provide theoretical support for future ophthalmological and biomedical engineering applications, including ocular diagnostics and protective device design. Full article

Background: Lumbar facet joints are a significant source of chronic low back pain (CLBP), and medial branch blocks (MBBs) are the widely accepted reference diagnostic approach for diagnosis. However, clinical response varies. This study aims to investigate whether sagittal spinopelvic alignment parameters can predict the clinical efficacy of MBB in patients with facet-mediated CLBP. Methods: In this prospective observational study, 110 patients (aged 40–80) with facet-related CLBP underwent diagnostic MBBs using a double-block protocol. Spinopelvic parameters, including pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), and lumbar lordosis (LL), were measured on standing lateral radiographs. Clinical response was defined as a ≥80% reduction in Visual Analog Scale (VAS) scores. Data were analyzed using multivariate logistic regression and Receiver Operating Characteristic (ROC) curves. Results: Responders (n = 68) were significantly younger and had a lower BMI than non-responders (n = 42) (p < 0.05). Non-responders exhibited significantly higher PI–LL mismatch (18.6° ± 7.4 vs. 3.9° ± 4.2, p < 0.001), higher PT (23.6° ± 5.1 vs. 17.4° ± 4.5, p < 0.001), and lower LL (35.8° ± 7.2 vs. 45.2° ± 6.4, p < 0.001). ROC analysis identified a PI–LL mismatch threshold of >12.5° as the strongly associated with negative short-term diagnostic response (AUC = 0.892). Multivariate analysis confirmed that PI–LL mismatch > 12.5° was a potential associated factor within the investigated model of poor response (OR: 4.25, 95% CI: 2.10–8.60, p < 0.001), while age and BMI were not significant in the adjusted model. Conclusions: Sagittal spinopelvic malalignment, specifically an increased PI–LL mismatch, is strongly associated with reduced diagnostic utility of MBB. Integrating biomechanical assessment into clinical decision-making may improve patient selection and treatment outcomes for facet-mediated pain. Full article

Background: Custom-made subperiosteal implants have re-emerged as a valuable option for the rehabilitation of patients with severe maxillofacial atrophy and post-oncological defects. Despite advances in digital workflows and implant design, their unique anatomical, biological, and prosthetic characteristics pose specific challenges for long-term maintenance, and no dedicated standardized guidelines are currently available. Methods: This narrative review critically appraises the available literature on implant maintenance and related fields. A comprehensive search was conducted across PubMed, Scopus, and Web of Science, including studies on peri-implant maintenance, supportive periodontal therapy, full-arch and zygomatic implant rehabilitations, and subperiosteal implants. Due to the lack of direct evidence, a qualitative narrative synthesis was adopted to develop preliminary clinical considerations for maintenance of custom-made subperiosteal implants. These considerations should be interpreted as an expert-informed perspective rather than validated clinical guidelines. Results: Conventional maintenance protocols developed for endosseous implants are not directly transferable to subperiosteal implants due to differences in the implant–tissue interface, biomechanics, diagnostic parameters, and hygiene accessibility. Key challenges include the absence of a conventional peri-implant sulcus, possible implant exposure, complex prosthetic geometries, and potential susceptibility to biofilm accumulation in areas with limited access. Evidence from related fields highlights the importance of structured maintenance, individualized risk-based follow-up, effective biofilm control, and patient-specific home-care strategies. Conclusions: Preliminary evidence-informed clinical considerations for the maintenance of subperiosteal implants are proposed, with emphasis on plaque control, individualized follow-up, descriptive clinical monitoring, and hygiene-oriented prosthetic and surgical planning. These considerations are not intended as validated guidelines, but as a practical starting point for clinical reasoning in an area where dedicated evidence remains limited. Full article

Maize hybrid seed production is a core factor in increasing maize yield. It is the key to ensure seed purity to remove tassels from female plants. This paper analyzes the inherent connections between seed production agronomy, biomechanics, computer vision, and intelligent devices at the system engineering level. The paper first elaborates on the role of crop growth models and genetic male sterility techniques in expanding the time window of mechanical operations. Secondly, based on the perception decision execution framework, this paper discusses how the biomechanical characteristics of male spikes directly determine the dynamic parameter design of the male removal actuator; in-depth analysis was conducted on the performance and limitations of deep learning algorithms in handling lighting changes, leaf occlusion, and high-throughput recognition in unstructured field environments. In addition, this paper compares the technical game between the detasseling success rate and leaf damage rate of two mainstream execution paths, cutting and extraction. This review highlights that future research should focus on the development of lightweight intelligent operation platforms and full-life-cycle digital decision-making systems, to realize high-efficiency and low-damage precision detasseling of seed maize. Full article

Background: Developmental dysplasia of the hip (DDH) is the most common congenital musculoskeletal disorder in newborns. Flexion–abduction orthoses are widely used in early treatment; however, in vivo data on their biomechanical load characteristics remain limited. This study aimed to evaluate axial force transmission in a hip flexion–abduction orthosis and to compare load patterns between healthy newborns and infants with DDH. Methods: In this exploratory observational study, 36 newborns (19 healthy, 17 with unilateral DDH) were examined within the first week of life. Axial forces transmitted through a Mittelmeier–Graf hip flexion–abduction orthosis (MGO) were measured using integrated force sensors under symmetrical and asymmetrical adjustment configurations. Intergroup comparisons were performed using non-parametric statistical tests. Results: Mean axial forces were significantly higher in healthy infants than in those with DDH under both symmetrical (4.02 N vs. 2.51 N; p = 0.019) and asymmetrical (3.67 N vs. 1.83 N; p = 0.001) conditions. Relative load corresponded to approximately 11–12% of body weight in healthy infants and 5–7% in the DDH group. No significant intra-individual differences were observed between dysplastic and contralateral hips. Orthosis configuration (symmetrical vs. asymmetrical) did not significantly affect load distribution. Conclusions: This exploratory in vivo study demonstrates that axial load transmission in a hip flexion–abduction orthosis is low and influenced by underlying hip pathology. Infants with DDH generate lower forces than healthy newborns, potentially reflecting altered biomechanics. As no significant differences were observed between orthosis configurations, symmetrical adjustment may be favored in clinical practice due to better usability and compliance. Further studies with larger cohorts are needed to confirm these findings. Full article

This study proposes a digital twin-based CPR compression measurement system (DTCMS) architecture for real-time monitoring of CPR compression. The system combines a load cell, an inertial measurement unit (IMU), a LabVIEW acquisition platform, and a CNN module to capture multi-modal motion characteristics during CPR repetitive compression training. A calibration-aware sensor fusion framework synchronizes heterogeneous signals, reduces drift, and enhances robustness under high-frequency operation. Real-time data acquisition, latency-controlled transmission, and digital twin visualization enable synchronized physical–virtual interaction. Experimental results demonstrate high accuracy (R² > 0.99), stable repeatability (coefficient of variation: CV < 3.5%), and reliable dynamic tracking. The compression depth error was maintained within ±1.5 mm, and synchronization latency remained below 0.2 s. Results confirm the proposed DTCMS architecture as a robust solution for real-time biomechanical monitoring and digital twin-based interactive systems. Compared with conventional single-sensor CPR monitoring systems, the proposed framework improves synchronization stability and sensing robustness through calibration-aware multi-sensor fusion. Full article