The Accuracy of Acetabular Component Position Using a Novel Method to Determine Anteversion

Background: This study compares the differences in acetabular component position, leg length discrepancy, and hip offset between the anterior and posterior approach. A novel method is applied to determine the acetabular anteversion using the C-arm tilt angle for the anterior approach. Methods: Hundred consecutive anterior total hip arthroplasties were matched according to gender, body mass index, and age to a cohort of 100 primary total hip arthroplasties operated on through a posterior approach. Postoperative radiographs were analyzed to determine cup inclination, cup anteversion, leg length discrepancy, and hip offset. Results: The mean inclination was 40.8 degrees (range 33 degrees-48 degrees) and 45.1 degrees (range 33 degrees-55 degrees) for the anterior and posterior approach, respectively. Using the new C-arm tilt plane technique, an average acetabular anteversion of 18.4 degrees (range 11 degrees-26 inverted perpendicular) was achieved with the anterior approach compared with 23.6 degrees (range 8 degrees-38 degrees) with the posterior approach. Hundred percent cups in the anterior group and 81% in the posterior group fell within the safe zone (P < .001). There was no difference in the overall hip offset between the operated side and the contralateral side for the anterior (P = .074) and posterior (P = .919) group. There was no difference in leg length discrepancy between the 2 approaches (P = .259). Conclusion: Intraoperative fluoroscopy-assisted direct anterior approach was associated with improved acetabular component positioning. However, no benefit was shown with regards to restoration of hip offset or leg length. (C) 2016 Elsevier Inc. All rights reserved.