Robotic Total Hip Arthroplasty in Atypical Hip Anatomy: Accuracy of Component Positioning and Clinical Outcomes in 192 Complex Cases.

Abstract

The objectives of this study were to determine the accuracy of component positioning, patient satisfaction, functional outcomes, component survivorship, and complications of robotic total hip arthroplasty (THA) in patients who have atypical hip anatomy. This study included 192 robotic THAs performed in 182 patients for developmental dysplasia of the hip (n = 122), Leg-Calve-Perthes disease (n = 27), slipped capital femoral epiphysis (n = 20), previous acetabular fracture (n = 12), and skeletal dysplasia (n = 11). Predefined radiological outcomes, patient satisfaction, University of California at Los Angeles (UCLA) activity score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Oxford Hip Score (OHS), Forgotten Joint Score (FJS), component survivorship, and any complications were recorded. The mean follow-up time was 3.8 ± 1.7 years (range, 2.1 to 5.4). Robotic THA was associated with high levels of accuracy in executing the planned horizontal (root mean square error (RMSE) 1.5 ± 1.4 mm) and vertical centers of rotation (RMSE: 1.8 ± 1.7 mm), combined offset (RMSE: 2.9 ± 3.8 mm), and leg-length correction (RMSE: 1.5 ± 1.4 mm). Acetabular component positioning within Lewinnek's safe zones was 94.7%, and Callanan's safe zones was 93.8%. The median patient satisfaction score was 90 (interquartile range (IQR), 85 to 95), the median WOMAC score was 18 (IQR, 12 to 20), and the mean FJS score was 77.8 ± 10.8 at final follow-up. Robotic THA was associated with improvements in the mean UCLA (P < 0.001) and OHS (P < 0.001) at final follow-up. The five-year survivorship was 98.8% (95% CI [confidence interval]: 95.8 to 100) with implant revision for any reason as the end point. Robotic THA in patients who have atypical hip anatomy was associated with high levels of accuracy in executing the planned component positioning. In this challenging patient population, robotic THA was associated with encouraging early component survivorship, satisfactory functional outcomes, and low risk of complications at short-term follow-up.