PELVIC MUSCLE AND ACETABULAR CONTACT FORCES DURING GAIT

Locations, magnitudes, and directions of pelvic muscle and acetabular contact forces are important to model the effects of abnormal conditio ns (e.g., deformity, surgery) of the hip accurately. Such data have no t been reported previously. We computed the three-dimensional location s of all pelvic muscle and acetabular contact forces during level gait . The approach first required computation of the intersegmental joint resultant forces and moments using limb displacement history, foot-flo or forces, and estimated limb inertial properties from one subject. Th e intersegmental resultant moments were then distributed to the muscle s using a 47-element muscle model and a non-linear optimization scheme . Muscle forces were vectorally subtracted from the intersegmental res ultants to compute the acetabular contact forces. While the peak joint force magnitudes are similar to those reported previously for the fem ur, the directions of pelvic contact forces and muscle forces varied c onsiderably over the gait cycle. These variations in contact force dir ections and three-dimensional forces could be as important as the cont act force magnitudes in performing experimental or theoretical studies of loads and stresses in the periacetabular region. (C) 1997 Elsevier Science Ltd.