INTRODUCTION/OBJECTIVES:Radial tears of the lateral meniscus disrupt the circumferential collagen fibers responsible for converting axial compression into hoop tension. Although their clinical impact is well recognized, the underlying physics of stress redistribution remains poorly quantified and rarely visualized. The objective of this study was to model and mechanically characterize how radial tears alter contact stress distribution using solid-mechanics principles and finite element analysis (FEA), and to determine whether anatomic repair restores hoop-stress continuity. METHODS:A three-dimensional FEA model of a healthy knee was reconstructed from high-resolution 3-T magnetic resonance imaging (MRI). Four conditions were simulated under identical loading: intact meniscus, 50% partial radial tear, complete (100%) radial tear, and anatomic repair. A 1000-N axial load was applied with a friction coefficient of 0.02. Primary outcomes included femorotibial contact area, peak contact stress, and qualitative stress-flow continuity, assessed through vector and heat map trajectories. Model performance was validated against published cadaveric and computational benchmarks. Repeated measures analysis of variance (ANOVA) with Bonferroni correction was used to compare conditions. RESULTS:The intact meniscus demonstrated uniform stress distribution with a mean contact area of 110 ± 8 mm2 and peak stress of 1.2 ± 0.2 MPa. A 50% radial tear reduced contact area to 80 ± 7 mm2 (-27%) and increased peak stress to 2.1 ± 0.3 MPa (p < 0.001). A complete radial tear further decreased contact area to 35 ± 6 mm2 (-68%) and tripled peak stress to 3.3 ± 0.4 MPa (2.8-fold increase; p < 0.001). Anatomic repair restored 86% of baseline contact area (95 ± 7 mm2) and normalized peak stress to 1.4 ± 0.3 MPa (p = 0.04 vs. intact; ns for intact vs. repaired). Stress flow analysis showed complete collapse of circumferential tension after full tear, with restoration of hoop-stress continuity following repair. Correlation with experimental benchmarks was strong (r = 0.91). CONCLUSION:This study quantitatively demonstrates that a radial meniscal tear disrupts circumferential load transmission, converting uniform hoop tension into focal condylar overload according to the fundamental principle that stress equals force divided by area. Finite element analysis showed that loss of circumferential continuity reduces contact area by nearly seventy percent and triples peak stress, whereas anatomic repair restores stress flow and re-establishes near-normal load sharing. These findings provide a physics-based explanation for the mechanical collapse that follows radial tears and reinforce that successful meniscal repair must restore the biomechanics of the hoop. LEVEL OF EVIDENCE:III - Experimental biomechanics.
Background:The management of Hoffa's fat pad during knee arthroscopy remains controversial. Resection is frequently performed to improve visualization or address inflammation, yet standardized criteria guiding the extent of excision are lacking, often leading to inconsistent postoperative outcomes. The purpose of this study was to develop a clinically applicable decision algorithm integrating clinical presentation, MRI characteristics, and intraoperative findings to guide the choice between preservation, partial resection, and complete excision of Hoffa's fat pad. Methods:A retrospective single-center review of 60 patients undergoing arthroscopic procedures involving the infrapatellar fat pad between 2016 and 2021, with follow-up completed through 2024, was performed. Patients were categorized by surgical management: preservation, partial resection, or complete resection. Demographic, clinical, and MRI parameters were correlated with functional outcomes (VAS, Kujala scores) at a minimum follow-up of 36 months. Results from the cohort were combined with evidence from a focused literature review to develop the final clinical decision algorithm. Results:All groups improved postoperatively, but preservation was associated with superior outcomes (VAS 2.1 ± 1.0; Kujala 92 ± 8) compared with partial (3.0 ± 1.3; 86 ± 10) and complete resection (3.8 ± 1.6; 82 ± 12; p < 0.05). MRI patterns correlated with surgical findings: diffuse edema favored conservative care, localized fibrosis benefited from partial resection, and nodular fibrosis required complete excision. The algorithm correctly classified 90% of satisfactory outcomes. Conclusion:The proposed algorithm provides a reproducible, evidence-informed approach for managing Hoffa's fat pad. Preservation should be prioritized to maintain biomechanical and synovial function, reserving resection for clearly defined fibrotic or mechanical lesions. Level of evidence:IV (retrospective therapeutic cohort study).
Introduction: Chronic stroke frequently causes structural and functional impairments in the tibialis anterior (TA) muscle, leading to foot-drop and altered gait kinematics. We investigated the relationship between ultrasonographic parameters of the TA muscle and functional gait performance in chronic stroke survivors. Methods: This cross-sectional, observational pilot study evaluated eight consecutive chronic stroke patients (>6 months post-stroke). Structural parameters of TA (rest and contraction thickness, pennation angle) were documented by ultrasound imaging. A dynamic feature calculated was the Contraction Index (CI = effort/resting thickness). Functional metrics included the Medical Research Council (MRC) muscle strength scale and the 10-Meter Walk Test (10MWT) for gait velocity. Results: Statistical analysis revealed a moderate negative correlation trend between resting TA muscle thickness and functional gait speed (r = -0.618, p = 0.102). Conversely, a moderate positive correlation trend was found (r = 0.548, p = 0.160). Ultrasound imaging successfully differentiated three distinct pathological phenotypes: an atrophic phenotype (low pennation angle, flaccid muscle failure), a severely shortened spastic phenotype (increased resting thickness, high pennation angle, pathological CI < 1.0), and a spastic co-contraction loop. Patients with the atrophic phenotype achieved high mechanical efficiency with an ankle-foot orthosis (AFO), whereas the spastic phenotype exhibited resistance against the orthotic device. Conclusions: Musculoskeletal ultrasound provides objective parameters for post-stroke TA muscle remodeling and contributes to completing the assessment and therapy. Identifying specific structural muscle phenotypes allows clinicians to optimize target-specific neurorehabilitation strategies, predict AFO efficiency, and guide antispastic interventions such as botulinum toxin injections.
El estudio analiza la prevalencia de lesiones por presión (LPP) en 100 pacientes adultos de diferentes áreas de hospitalización. Tiene diseño cuantitativo y transversal, realizado en un hospital de segundo nivel. Se utilizó la escala de Braden para evaluar el riesgo y la clasificación Grupo Nacional para el Estudio y Asesoramiento en Úlceras por Presión y Heridas crónicas (GNEAUPP) para categorizar las lesiones. Se identificó una prevalencia puntual del 22%, con mayor incidencia en adultos mayores (25.9%) y una edad promedio de 73 años. La puntuación Braden más común fue de 8 puntos, indicando alto riesgo. Las categorías predominantes fueron I y II, localizadas principalmente en sacro, talón y glúteo. Los resultados reflejan una prevalencia significativa asociada con la calidad del cuidado brindado, destacando la necesidad de fortalecer la cultura de prevención y las intervenciones del personal multidisciplinario en la atención y manejo de úlceras por presión.
