Direct anterior total hip arthroplasty gait biomechanics at three and six months post surgery

Abstract

Osteoarthritis (OA) is a degenerative disease that affects the cartilage at the ends of bones, causing joint stiffness and pain with subsequent compensatory gait mechanics [1-5]. Hip OA patients often develop gait adaptations to minimize the pain experienced when performing activities of daily living. These gait adaptations include Trendelenburg gait{6J and decreased: gait velocities, step and stride length [7-13], external hip moments (adduction, extension and internal rotation) [14-16], and internal hip moments (abduction and external rotation) [7, 11]. Lower internal moments of the hip may be attributed to decreased muscular torque in the involved hip abductor and extensor muscle groups [71. External moments provide a reflection of how an antalgic gait allows compensation for muscle weakness in the stance limb [16]. Lateral trunk lean shifts the center of mass towards the stance limb and decreases the external adduction moment arm decreasing the external joint moments [15]. Conversely, Trendelenburg gait causes hip drop on the nonstance limb increasing the external adduction moment arm on the stance limb causing hip OA patients to walk slower thus producing a lower vertical ground reaction force. Once these compensatory measures become intolerable the most effective treatment is total hip arthroplasty (THA) [17, 18]. The goal of THA is to correct anatomical insufficiencies and to reduce pain and increase function [19-2 1].