JOA - 2026-06-12 - Journal Article
Robotic Total Hip Arthroplasty in Atypical Hip Anatomy: Accuracy of Component Positioning and Clinical Outcomes in 192 Complex Cases.
Kayani B, Enson J, Donaldson J, Miles J, Newman S, Jayadev C, Stammers J, Skinner JA
Topics
Key Takeaway
Robotic THA in 192 atypical hip anatomy cases achieved acetabular positioning within Lewinnek safe zones in 94.7% and 5-year implant survivorship of 98.8%.
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Summary
This study evaluated robotic THA accuracy and outcomes in 192 hips with atypical anatomy including DDH (n=122), LCPD (n=27), SCFE (n=20), prior acetabular fracture (n=12), and skeletal dysplasia (n=11). Robotic execution achieved center-of-rotation accuracy within RMSE 1.5–1.8 mm and leg-length correction RMSE of 1.5 mm. Five-year survivorship was 98.8%, with median patient satisfaction of 90/100 and mean FJS of 77.8.
Key Limitation
Short-term follow-up (mean 3.8 years) is insufficient to assess aseptic loosening rates, which typically manifest beyond 5–10 years and represent the primary long-term failure mode in this young, active population.
Original Abstract
BACKGROUND
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.
METHODS
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).
RESULTS
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.
CONCLUSION
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.