Elliptical defects create a more adverse biomechanical environment than circular defects in osteochondral lesion of the talus: a finite element analysis.

Introduction: Osteochondral lesion of the talus (OLT) is a common ankle injury that may disturb the biomechanical environment and contribute to progressive articular degeneration. However, in clinical practice, OLT is typically elliptical, whereas most biomechanical studies modeled OLTs as circular defects. This study aimed to compare circular and elliptical OLT defects of different sizes and locations using finite element analysis. Methods: A subject-specific ankle finite element model was reconstructed from CT data. Full-thickness circular and elliptical defects ranging from 25 to 200 mm Results: Compared with circular defects, elliptical defects generally produced higher peak stress and a more adverse redistribution pattern. In zone 4, differences between shapes became more evident in larger defects, and at 200 mm Conclusion: Defect shape substantially alters the biomechanical environment of OLT. Compared with circular defects, elliptical defects produce greater stress concentration, earlier stress redistribution, and a more unfavorable stress pattern, especially in larger lesions. These findings suggest that defect shape should be considered in biomechanical assessment and clinical evaluation.