Background: The benefits of robotic techniques for implanting femoral components during THA are still controversial.
Questions/purposes: The purpose of this study was to prospectively compare the results and complications of robotic-assisted and hand-rasping stem implantation techniques.
Method: The minimum followup was 5 years (mean, 67 months; range, 60-85 months). One hundred forty-six primary THAs on 130 patients were included in this study. Robot-assisted primary THA was performed on 75 hips and a hand-rasping technique was used on 71 hips.
Results: At 2 and 3 years postoperatively, the Japanese Orthopaedic Association (JOA) clinical score was slightly better in the robotic-assisted group. At 5 years followup, however, the differences were not significant. Postoperative limb lengths of the robotic-milling group had significantly less variance than the hand-rasping group. At 2 years postoperatively, there was significantly more stress shielding of the proximal femur in the hand-rasping group; this difference was more significant 5 years postoperatively.
Conclusions: Substantially more precise implant positioning seems to have led to less variance in limb-length inequality and less stress shielding of the proximal femur 5 years postoperatively.
Level of evidence: Level II, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.