LOAD PREDICTIONS AT THE HIP-JOINT - COMPU TER ANALYSES USING A 3D HUMAN MULTIBODY MODEL

Multibody analysis was applied to construct an advanced model of the h uman body, where the large joints and complete mass and inertial prope rties were implemented. The model represents the 50th-percentile rank of a male adult. The hip joint is controlled by three muscle forces. T he muscle coordinates were taken from a data source, previously collec ted by our group. The model enables one to analyze 3D hip joint forces with respect to various joint angles and represents conceptually an i mprovement of the classical method of graphical statics, which was est ablished by Pauwels [15]. A hip joint load of three times body weight was found in the single leg stance. A load of 3.7 times body weight wa s calculated when simulating a knee flexion angle of 90-degrees, and a ventral inclination of the resultant hip joint force was seen. A cons tant amount of gluteus medius muscle force was observed during flexion . An increasing flecting moment at the hip joint, however, had to be b alanced by a significantly increased gluteus maximus muscle force. As a consequence, torsional forces can be studied by the system presented here and should also be considered when testing stems of hip prothese s. External muscle and joint forces are provided and can be used as in put data for stress analyses.