How do the femoral anteversion angle and neck-shaft angle influence muscle forces and joint loading during walking?

Abstract

Femoral deformities, e.g. increased or decreased femoral anteversion (AVA) and neck-shaft angle (NSA), can lead to pathological gait patterns, altered joint loads, and degenerative joint diseases. The mechanism how femoral geometry influences muscle forces and joint load during walking is still not fully understood. Hence, we conducted a comprehensive musculoskeletal modelling study to investigate the influence of femoral AVA and NSA on muscle forces and joint loads during walking. We created 25 musculoskeletal models with a variety of NSA and AVA. For each model we calculated moment arms, muscle forces, muscle moments, and joint loads based on motion capture data of a person with a typical gait pattern. We found a significant increase in co-contraction of hip and knee joint spanning muscles in models with increasing AVA and NSA, which led to a substantial increase in hip and knee joint contact forces. Decreased AVA and NSA had a minor impact on muscle and joint contact forces. Neglecting an individual’s femoral geometry when estimating joint contact forces can lead to errors above five times body weight. Knowing the influence of femoral geometry on muscle forces and joint loads can help clinicians to improve treatment strategies in patients with femoral deformities.