Individual muscle contributions to ground reaction and to joint contact, ligament and bone forces during normal gait

Recent developments in musculoskeletal modelling have enabled numerous studies to explore how individual muscles contribute to progression, support and mechanical loading during gait. However, the literature still lacks data on the contributions of musculo-tendon forces to several structures, making it difficult to determine the primary contributors. The aim of the present study was thus to provide a comprehensive investigation of individual muscle contributions to ground reaction (i.e. 3D ground reaction force and moment), and to joint contact, ligament and bone (i.e. compression–traction of bony segments) forces during normal gait. We used a 3D lower limb musculoskeletal model coupled with a static optimisation method using a pseudo-inverse, which indeed yielded data on individual muscle contributions currently missing from the literature. We report the individual muscle contributions to (i) 3D ground reaction force and moment, (ii) hip, tibiofemoral, patellofemoral and ankle joint contact forces, (iii) tibiofemoral and ankle ligament forces, and (iv) femur, patella and tibia bone forces. In line with the recent literature, the primary contributors are the vastii, gluteus medius, soleus, rectus femoris, gemellus, quadratus femoris, gluteus maximus, and adductors. While the current observations are made on a generic model, the present method offers a comprehension tool that can shed light on the underlying mechanisms governing the musculoskeletal system.