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.