In vivo kinematic analysis of patients with robotic-assisted total hip arthroplasty during gait at 1-year follow-up

Background Suboptimal component positioning has been suggested as an important contributing factor to postoperative gait asymmetry. The aim of this study is to determine whether robotic arm-assisted THA better restores gait symmetry than freehand THA. Methods Component orientation and positioning parameters and in vivo gait kinematics were quantified for implanted and native hips in 20 robotic arm-assisted and eight freehand THA patients, using a validated combined three-dimensional modeling technique. Results Although neither THA procedure fully restored the native hip geometry, the robotic arm-assisted THA showed a better accuracy than freehand THA, with lower root mean square errors of component orientations. Gait asymmetry was not fully eliminated by either robotic arm-assisted or freehand THA, with increased internal rotation most notably observed in the implanted hip. Conclusion Improved accuracy in restoring native hip geometry achieved by the robotic arm-assisted THA procedure did not fully translate into improved gait symmetry.