The learning curve of robotic-arm assisted acetabular cup positioning during total hip arthroplasty

Robotic-arm assisted surgery aims to reduce manual errors and improve the accuracy of implant positioning and orientation during total hip arthroplasty (THA). The objective of this study was to assess the surgical team’s learning curve for robotic-arm assisted acetabular cup positioning during THA.

This prospective cohort study included 100 patients with symptomatic hip osteoarthritis undergoing primary total THA performed by a single surgeon. This included 50 patients receiving conventional manual THA and 50 patients undergoing robotic-arm assisted acetabular cup positioning during THA. Independent observers recorded surrogate markers of the learning curve including operative times, confidence levels amongst the surgical team using the state-trait anxiety inventory (STAI) questionnaire, accuracy in restoring native hip biomechanics, acetabular cup positioning, leg-length discrepancy, and complications within 90 days of surgery.

Cumulative summation (CUSUM) analysis revealed robotic-arm assisted acetabular cup positioning during THA was associated with a learning curve of 12 cases for achieving operative times (p < 0.001) and surgical team confidence levels (p < 0.001) comparable to conventional manual THA. There was no learning curve of robotic-arm assisted THA for accuracy of achieving the planned horizontal (p = 0.83) and vertical (p = 0.71) centres of rotation, combined offset (p = 0.67), cup inclination (p = 0.68), cup anteversion (p = 0.72), and correction of leg-length discrepancy (p = 0.61). There was no difference in postoperative complications between the two treatment groups.

Integration of robotic-arm assisted acetabular cup positioning during THA was associated with a learning curve of 12 cases for operative times and surgical team confidence levels but there was no learning curve effect for accuracy in restoring native hip biomechanics or achieving planned acetabular cup positioning and orientation.