BACKGROUND: Clinical outcomes of total hip arthroplasty (THA) for Crowe type IV are poorer than for Crowe type I, because it is more difficult to accurately position the acetabular components. This study aimed to examine the accuracy of the computed tomography (CT)-based navigation system for acetabular component positioning in primary THA for Crowe type IV. METHODS: From 2006 to 2018, 29 patients who underwent 34 primary THAs for Crowe type IV were enrolled in the "Type IV" group and 32 patients who underwent 34 THAs for Crowe type I were enrolled in the "Type I" group, formed by matching patients in the Type IV group on age, gender, body mass index, and surgical approach. We investigated (1) the accuracy of the cup size between that at preoperative planning and that actually implanted and (2) the mean deviation of the cup angle and 3-dimensional position of acetabular components between preoperative plan and postoperative records. RESULTS: The accuracy of the cup size was 79.4% and 94.1% in the Type IV and Type I groups, respectively, without a statistically significant change detected (P = .075). The mean deviations of the cup angle and 3-dimensional position were comparable in both groups. CONCLUSION: Using the CT-based navigation system, it was possible to accurately implant the acetabular component for Crowe type IV, and the accuracy was comparable to that for Crowe type I. The CT-based navigation system is a useful intraoperative tool to accurately implant the acetabular component, especially with severe pelvic deformities such as Crowe type IV.
BACKGROUND: Clinical outcomes of total hip arthroplasty (THA) for Crowe type IV are poorer than for Crowe type I, because it is more difficult to accurately position the acetabular components. This study aimed to examine the accuracy of the computed tomography (CT)-based navigation system for acetabular component positioning in primary THA for Crowe type IV. METHODS: From 2006 to 2018, 29 patients who underwent 34 primary THAs for Crowe type IV were enrolled in the "Type IV" group and 32 patients who underwent 34 THAs for Crowe type I were enrolled in the "Type I" group, formed by matching patients in the Type IV group on age, gender, body mass index, and surgical approach. We investigated (1) the accuracy of the cup size between that at preoperative planning and that actually implanted and (2) the mean deviation of the cup angle and 3-dimensional position of acetabular components between preoperative plan and postoperative records. RESULTS: The accuracy of the cup size was 79.4% and 94.1% in the Type IV and Type I groups, respectively, without a statistically significant change detected (P = .075). The mean deviations of the cup angle and 3-dimensional position were comparable in both groups. CONCLUSION: Using the CT-based navigation system, it was possible to accurately implant the acetabular component for Crowe type IV, and the accuracy was comparable to that for Crowe type I. The CT-based navigation system is a useful intraoperative tool to accurately implant the acetabular component, especially with severe pelvic deformities such as Crowe type IV.