In-vivo 3-Dimensional gait symmetry analysis in patients with bilateral total hip arthroplasty.

Although three-dimensional (3D) asymmetry has been reported in unilateral THA patients during gait, it is not well understood whether asymmetric hip kinematics during gait persist in bilaterally operated THA patients. The purpose of this study was to compare the in vivo 3D kinematics and component placement between bilateral and unilateral THA patients during gait. Eight bilateral and thirty-three unilateral THA patients were evaluated for both hips during treadmill gait using a validated combination of 3D computer tomography-based modeling and dual fluoroscopic imaging system (DFIS). The in vivo 3D kinematics of the unilateral THA group was first assessed. The magnitudes of kinematics and component placement difference between implanted hips in the bilateral THA group and between the implanted and non-implanted hips in the unilateral THA group were compared. The study results showed asymmetric gait kinematics in the unilateral THA group. Although the magnitude of kinematics differences between sides for both the bilateral and unilateral THA groups did not change significantly for hip rotations (p > 0.05), the bilaterally operated THA group has significantly lower magnitude of hip gait translation difference. Significant reduction in the magnitude of the acetabular cup adduction, stem adduction, and combine hip anteversion and adduction difference was observed in the bilateral THA group (p < 0.05). Our findings demonstrated that despite significant improvements of component placement and reduced magnitude of hip gait translation difference between implanted hips in the bilateral THA group, asymmetric hip kinematic rotations persisted in patients with bilateral THA during gait.