A comparison between robotic-assisted and manual implantation of cementless total hip arthroplasty.
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.