Validation of the Accuracy of Robotic Arm-Assisted Total Hip Arthroplasty After Rotational Acetabular Osteotomy: A Propensity-Matched Controlled Study

Background Robot-assisted total hip arthroplasty (THA) improves the accuracy of implant placement. However, acetabular cup positioning in patients with a history of pelvic osteotomy remains technically demanding, and the benefit of robotic assistance in such cases has not been established. This study aimed to evaluate the accuracy of acetabular cup placement using robot-assisted THA in patients who previously underwent rotational acetabular osteotomy (RAO), a type of pelvic osteotomy performed for hip dysplasia. Methods We retrospectively reviewed 23 patients (25 hips) who underwent robot-assisted THA after RAO between January 2021 and February 2023 (RAO group). A control group of 100 patients who underwent unilateral robot-assisted THA for mild hip dysplasia (Crowe type I) between January 2022 and December 2022 was established. One-to-one propensity score matching was performed based on age, sex, and body mass index. The errors and absolute values of radiographic inclination, radiographic anteversion, and the mediolateral, anteroposterior, and superoinferior axes were measured using three-dimensional planning software. Results No significant differences were observed between the RAO and control groups in the errors of radiographic inclination, radiographic anteversion, mediolateral, anteroposterior, or superoinferior axes ( P = .290–.923) or in their absolute values ( P = .103–.734). Conclusions Robot-assisted THA enabled acetabular cup placement in patients with prior RAO, with no significant differences in implantation errors compared with primary THA for mild hip dysplasia. These findings suggest that previous RAO does not adversely affect the accuracy of robot-assisted THA.