A CALCULATION OF THE FORCES ACTING ON THE HUMAN ACETABULUM DURING WALKING - BASED ON IN-VIVO FORCE MEASUREMENTS, KINEMATIC ANALYSIS AND MORPHOMETRY

Information about the loading of the human acetabulum during walking i s necessary for a functional understanding of the morphology of the pe lvic girdle and the hip joint as well as for the optimization of endop rosthetic therapy in osteoarthritis. For this purpose, experimental da ta of the forces acting on the femur in walking taken from the literat ure [Bergmann et al.: J. Biomech. 1993,26, 969-990] were combined with our own kinematic and morphometric data, to transform the force vecto rs from the femoral into a pelvic and an acetabular frame. During the walking cycle, the resultant force vector takes a rather constant cour se relative to the pelvis and its orientation seems to be highly regul ated to act within a small range of angles. Only small deviations occu r from the angles against the vertical which the resultant peak force forms in the frontal plane (F=11 degrees, medially orientated) and in the sagittal plane (S=5 degrees, ventrally orientated). The experiment al results form the basis for a model of the incongruous hip joint as an elastic joint, the femoral head being centered between compliant el ements.