Comparison of accuracy of acetabular cup placement using manual versus robotic-assistance in the same patient cohort undergoing robotic-assisted total hip arthroplasty

Accurate acetabular component orientation is essential for restoring biomechanics and implant longevity in total hip arthroplasty (THA). While robotic assistance has been shown to improve component positioning, comparisons across patient cohorts remain confounded by inter-patient variability. This study aimed to evaluate the accuracy of manual versus robotic acetabular cup impaction using an intra-patient sequential design within the same joint. A prospective observational study was undertaken with 100 robotic-assisted THA (with Mako robotic arm). Following CT-based preoperative planning, a trial acetabular cup was manually impacted and its orientation recorded using intraoperative stereotactic tracking. The trial was then removed, and the definitive cup was implanted using robotic assistance. Deviation from planned patient-specific cup inclination and anteversion was estimated. Overall, the mean age was 44.4 ± 16.1 years, and 71% were males. The mean absolute deviation in anteversion was 4.71 ± 4.210 for manual impaction and 0.93 ± 0.970 for robotic impaction (p < 0.001). The deviation in inclination was 3.5 ± 4.00 with manual and 0.94 ± 1.330 with robotic placement (p < 0.001). Agreement analysis demonstrated that robotic placement had narrower limits and lower bias in cup orientation accuracy compared to manual placement. Robotic-assisted THA achieved significantly greater accuracy and consistency in acetabular cup orientation compared with manual impaction under identical anatomical conditions. While intraoperative precision was improved, further long-term studies are required to determine whether this translates into superior clinical outcomes and implant survivorship.