Surgical accuracy of implant positioning in robotic-assisted versus conventional total hip arthroplasty – Experience of a Joint Replacement Centre in Hong Kong

Introduction : Total hip arthroplasty (THA) is a common orthopaedic procedure that significantly alleviates pain and enhances the quality of life for patients with hip osteoarthritis. Precise implant placement is critical for successful outcomes. Robotic-assisted THA has been developed to improve surgical accuracy and predictability, offering three-dimensional computed tomography-based planning and haptic guidance during key steps of surgery such as reaming and cup impaction. This study aims to compare (i) the accuracy of implant positioning between robotic-assisted and conventional THA, and (ii) other intra-operative and post-operative outcomes, including blood loss, operative time, length of stay, and associated complications. Materials and Methods : In total, 97 THA cases performed between November 2017 and October 2023, with a minimum follow-up of one year, were retrospectively analyzed. Fifty patients underwent robotic-assisted THA, while 47 received conventional THA. Demographic data, radiographic outcomes, surgical time, blood loss, length of stay, and surgical complications were evaluated. Intra- and Inter-observer reliability of radiographic measurements was confirmed. Results : Robotic-assisted THA demonstrated significantly greater accuracy and consistency in achieving targeted acetabular inclination and anteversion (p < 0.001). More cases in this group fell within the Lewinnek (<0.001) and Callanan safe zones (<0.001). Improvements in femoral offset ( p < 0.001) and maintenance of global offset ( p = 0.264) were also observed. More cases achieved balanced limb length discrepancy ( p = 0.047). No significant differences were found in operative time ( p = 0.196), blood loss ( p = 0.775), or length of stay ( p = 0.236). Similar rates of surgical complication were observed in both groups. Discussion and conclusion : Robotic-assisted THA provides more precise and consistent implant positioning without increasing operative time, blood loss, length of hospital stay, or associated complications.