Biomechanical analysis of femoral stress response during squatting: A combined multibody dynamics and finite element...

Inappropriate squat postures are prone to induce femoral musculoskeletal injuries. Knee flexion angle (α) and stance width (L) are critical governing parameters, yet their specific impacts on femoral mechanical responses during squatting have not been fully elucidated. This study aims to analyze the influence mechanisms of these kinematic factors on femoral stress distribution.

This study employed a combined multibody dynamics and finite element analysis (MBD-FEA) method. Hip joint reaction forces during squats under varying α and L conditions were computed via the AnyBody Modeling System and subsequently applied as boundary conditions to a femoral finite element model, to clarify the mechanisms by which α and L influence femoral mechanical responses.

The results demonstrated that during squatting, tensile stress on the anterior femoral shaft was consistently greater than compressive stress on the posterior shaft, while tensile stress in Ward's triangle was persistently lower than compressive stress in the posterior femoral neck. As α increased, femoral stress displayed a nonlinear growth pattern characterized by "a rapid initial rise followed by slowing growth." The effect of L on femoral stress was dependent on α: when α < 105°, stress increased progressively with increasing L; when α > 105°, this trend was reversed.

From a biomechanical standpoint, this study provides a theoretical foundation for the optimization of squat postures and the prevention of associated injuries.