Robot-assisted total hip arthroplasty (THA) was associated with a shorter learning curve, greater implant accuracy, and reduced team stress than conventional THA when performed by a junior surgeon: a comparative study.

Both conventional and robot-assisted total hip arthroplasty (THA) require a learning curve, and surgical team stress may vary with accumulated experience. This study aimed to define the learning curve of junior surgeons performing conventional and robot-assisted THA, and to compare implant-positioning outcomes and surgical team stress between the two approaches. We included patients who underwent THA performed by a junior joint surgeon between January 2025 and July 2025. Patients were allocated to either the robot-assisted THA (R-THA) group or the conventional THA (C-THA) group. The learning curve was assessed using cumulative summation (CUSUM) analysis of operative time. Implant positioning was evaluated using cup inclination and anteversion, Lewinnek's safe zone attainment, difference in femoral offset (ΔFO), and leg length discrepancy (LLD). Preoperative anxiety of the primary surgeon and intraoperative stress of the surgical team were assessed using the State-Trait Anxiety Inventory (STAI) and the Surgery Task Load Index (SURG-TLX), respectively. The primary outcome was the learning curve, with secondary outcomes being between-group comparisons and exploratory outcomes consisting of phase-based comparisons after stratifying both groups into learning and proficiency phases. A total of 50 patients were included in the R-THA group and 49 in the C-THA group. CUSUM analysis showed learning curve lengths of 21 cases in the R-THA group and 26 cases in the C-THA group. Compared with the C-THA group, the R-THA group showed smaller LLD, cup anteversion closer to the planned 20°, a higher proportion of cups within the Lewinnek's safe zone, and lower STAI and SURG-TLX scores for the primary surgeon, first assistant, and second assistant. Exploratory analyses showed that, during the learning phase, the R-THA group achieved cup anteversion closer to the planned 20° than the C-THA group. During the proficiency phase, the R-THA group demonstrated a higher proportion of cups within the Lewinnek's safe zone and lower SURG-TLX scores. After the learning phase, both groups showed reductions in STAI and SURG-TLX scores. For the junior surgeon, the learning curves were 21 cases for robot-assisted THA and 26 cases for conventional THA. Compared with conventional THA, robot-assisted THA may be associated with more favorable implant positioning and lower surgical team stress.