Approach-specific learning curves for operative efficiency in robotic-assisted total hip arthroplasty

Background: Robotic-assisted total hip arthroplasty (RA-THA) has been shown to improve the accuracy of component positioning, but the learning curve for efficient operative performance remains debated. Methods: We retrospectively reviewed 579 consecutive RA-THA procedures performed between June 2021 and June 2023 at a single centre using the MAKO robotic system. Surgeon 1 performed cases via the direct anterior approach (DAA), and Surgeon 2 via the posterolateral approach (PL). A historical cohort of conventional manual THA served as a control group. Operative time was the primary outcome. Learning curves were assessed using cumulative summation (CUSUM) analysis, with proficiency defined as the inflection point at which operative times stabilised. Demographic variables were compared among learning-phase, proficiency-phase, and conventional cohorts. Results: A total of 434 DAA and 145 PL RA-THA cases were analysed. For the DAA cohort, proficiency was achieved after 73 cases; mean operative time decreased from 97.9 ± 17.5 minutes during the learning phase to 79.7 ± 16.6 minutes during the proficiency phase ( p < 0.001). For the PL cohort, proficiency was achieved after 41 cases; operative time decreased from 89.7 ± 21.6 minutes to 72.8 ± 14.5 minutes ( p < 0.001). Compared with conventional THA, proficiency-phase RA-THA operative times were slightly shorter for the DAA (−3 minutes, p = 0.045, small effect size) and comparable for the PL approach ( p = 0.632). No significant differences in baseline demographics were observed among groups. Conclusions: Robotic-assisted THA is associated with substantial learning curves for operative efficiency, with longer thresholds observed for the DAA compared with the PL approach. Although RA-THA has been associated with early improvements in implant positioning accuracy, operative efficiency appears to improve more gradually with experience. Institutions adopting RA-THA should anticipate approach-specific learning curves, implement structured training pathways, and prepare surgical teams for an initial adaptation period.