Lengths and lever arms of hip joint muscles: geometrical analyses using a human multibody model

Multibody analysis was applied in order to construct a model of the human body including the large joints and 31 muscles crossing the hip and knee. The model represents the 50th percentile rank of a male adult. The model was used to study the influence of hip joint angles on the distances between muscular insertions and origins and on muscular lever arms. Maximum and minimum muscle lengths were determined during inplane and combined hip joint motions. Maximum and minimum lever arms and their flexion/extension, abduction/adduction and rotation components during inplane hip motions were computed. A good qualitative agreement was obtained with the literature data; being suitably compared with the results presented here. It is concluded that a large geometrical data base on hip joint muscle lengths and lever arms is provided which was not previously available and which may be of significant value in morphometry, musculoskeletal research and biomechanical modelling.