Precision of robotic guided instrumentation for acetabular component positioning.

Robotic computerized instrumentation that guides bone preparation and cup implantation in total hip arthroplasty was studied. In 38 patients (43 hips) intraoperative cup inclination and anteversion were validated by postoperative CT scans. Planned inclination was 39.9°±0.8° and with robotic instrumentation was 38. 0°±1.6° with no outliers of 5°; on the postoperative CT scan there were 5 outliers (12%). Planned anteversion was 21.2°±2.4° and intraoperatively was 20.7°±2.4° with no outlier of 5°; on the CT there were 7 outliers (16%). The center of rotation (COR) was superior by a mean 0.9±4.2 mm and medial by 2.7±2.9 mm. This robotic instrumentation achieved precision of inclination in 88%, anteversion in 84% and COR in 81.5%.