Changes in gait biomechanics and muscular torque after total hip arthroplasty in osteoarthritic hip patients

M.S. University of Hawaii at Manoa 2013.Includes bibliographical references.Purpose: Osteoarthritis is a prevalent hip disease primarily affecting older populations, causing pain, muscle weakness, contracture, and gait abnormalities. When conservative treatments have failed, total hip arthroplasty (THA) is often the prescribed treatment to correct osteoarthritic changes. Although THA can reduce pain and improve function, gait abnormalities persist long after surgery. Therefore, the purpose of this study was to evaluate the effects of THA on hip biomechanics, muscle torque, gait velocity, and pain in osteoarthritic hip patients preoperatively and postoperatively. Methods: Biomechanical gait analysis was completed for 15 THA and 11 healthy control participants using a three-dimensional motion capture system. Gait, hip muscle torque, walking velocity, and pain data were collected during six sessions: preoperatively; and postoperatively, at three and six weeks, and at three and six months. Results: Differences in hip extension angle, external hip extension moment, hip flexion, extension, and abduction torque, walking velocity, and pain were revealed between groups. The THA group demonstrated lower values and significantly higher improvements postoperatively than the experimental group. Initial decreases in hip flexor torque were observed within the first three weeks postoperatively. Six weeks postoperatively, a reduction in pain combined with increased extension angle contributed to improved muscle torque and gait characteristics. Conclusions: Osteoarthritic hip patients demonstrated diminished gait characteristics and muscular torque when compared to controls. While these gait characteristics improved post operatively they did not return to control values with the exception of hip extension and abduction torque, walking velocity, and pain level at six months postoperatively. Key Words: Total hip arthroplasty, hip kinematics, hip kinetics, Harris Hip Function Scale, hip muscle torqu