Asymmetric hip kinematics during gait in patients with unilateral total hip arthroplasty: in vivo 3-dimensional motion analysis.

Asymmetric limb loading has been reported in unilateral total hip arthroplasty (THA) patients during gait. However, restoration of 3D motion symmetry of the hip following unilateral THA remains unclear. The purpose of this study was to investigate the in vivo 3D kinematics of the hip in unilateral THA patients during gait. Eight unilateral THA patients were evaluated for both hips during treadmill gait using a dual fluoroscopic imaging system. Reduced hip range of motion in sagittal plane, decreased peak hip extension and asymmetric pelvic rotation of the THA were observed. Furthermore, significant pelvic anterior/posterior tilt asymmetry, higher internal rotation (increased by 8.6°±4.6°) during stance phase and higher adduction (increased by 4.5°±3.2°) during swing phase of the THA were found in this cohort of patients. The results demonstrated that there was 3D motion asymmetry of the hip and pelvis in unilateral THA patients during gait. The data could provide insights into optimizing kinematics and to restoring normal hip function after THA.