A prospective randomized controlled trial comparing CT-based planning with conventional total hip arthroplasty versus robotic arm-assisted total hip arthroplasty.

Aims: Achieving accurate implant positioning and restoring native hip biomechanics are key surgeon-controlled technical objectives in total hip arthroplasty (THA). The primary objective of this study was to compare the reproducibility of the planned preoperative centre of hip rotation (COR) in patients undergoing robotic arm-assisted THA versus conventional THA.
Methods: This prospective randomized controlled trial (RCT) included 60 patients with symptomatic hip osteoarthritis undergoing conventional THA (CO THA) versus robotic arm-assisted THA (RO THA). Patients in both arms underwent pre- and postoperative CT scans, and a patient-specific plan was created using the robotic software. The COR, combined offset, acetabular orientation, and leg length discrepancy were measured on the pre- and postoperative CT scanogram at six weeks following surgery.
Results: There were no significant differences for any of the baseline characteristics including spinopelvic mobility. The absolute error for achieving the planned horizontal COR was median 1.4 mm (interquartile range (IQR) 0.87 to 3.42) in RO THA versus 4.3 mm (IQR 3 to 6.8; p < 0.001); vertical COR mean 0.91 mm (SD 0.73) in RO THA versus 2.3 mm (SD 1.3; p < 0.001); and combined offset median 2 mm (IQR 0.97 to 5.45) in RO THA versus 3.9 mm (IQR 2 to 7.9; p = 0.019). Improved accuracy was observed with RO THA in achieving the desired acetabular component positioning (root mean square error for anteversion and inclination was 2.6 and 1.3 vs 8.9 and 5.3, repectively) and leg length (mean 0.6 mm vs 1.4 mm; p < 0.001). Patient-reported outcome measures were comparable between the two groups at baseline and one year. Participants in the RO THA group needed fewer physiotherapy sessions postoperatively (median six (IQR 4.5 to 8) vs eight (IQR 6 to 11; p = 0.005).
Conclusion: This RCT suggested that robotic-arm assistance in THA was associated with improved accuracy in restoring the native COR, better preservation of the combined offset, leg length correction, and superior accuracy in achieving the desired acetabular component positioning. Further evaluation through long-term and registry data is necessary to assess whether these findings translate into improved implant survival and functional outcomes.
Competing Interests: A. Fontalis reports a Freemasons' Royal Arch Fellowship with support of the Arthritis Research Trust, related to this study, and grants or contracts from the Onassis Foundation (scholarship ID: F ZR 065-1/2021-2022), unrelated to this study. S. Konan reports consulting fees from Smith & Nephew, as well as payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Smith & Nephew and AO Recon, all of which are unrelated to this study. F. S. Haddad reports a grant from Stryker, related to this study, as well as multiple study grants from Stryker, Smith & Nephew, Corin, National Institute for Health and Care Research, and International Olympic Committee, royalties or licenses from Smith & Nephew, Stryker, Corin, and MatOrtho, consulting fees from Stryker, payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Stryker, Smith & Nephew, Zimmer, AO Recon, and Mathys, support for attending meetings and/or travel from Stryker, Mathys, AO Recon, and The Bone & Joint Journal, all of which are unrelated to this article. F. S. Haddad is also Editor-in-Chief of The Bone & Joint Journal, incoming President of the International Hip Society, and Vice President of the European Hip Society.
(© 2024 The British Editorial Society of Bone & Joint Surgery.)