Assessment of 3D acetabular offset in total hip arthroplasty using conventional reaming technique

Background: Reconstruction of the hip center and appropriate offset is meaningful in total hip arthroplasty (THA). In our institution, THA is performed using the anterolateral supine (ALS) approach with intraoperative fluoroscopy, wherein the acetabulum is reamed using the conventional reaming technique. This study aimed to investigate and review 3D acetabular offset in ALS-THA and compare changes between the post-THA and the normal hips. Methods: : Seventy-three patients with unilateral disease and 73 joints (mean age 62.8 years, all female patients) underwent ALS-THA using the conventional reaming technique with intraoperative fluoroscopy at the same institution. The acetabular medial offset (AMO), acetabular superior offset (ASO), and acetabular anterior offset (AAO, posterior +) were measured, and the amount of change in the unaffected hip joint and implanted hip joint was examined. Results: : The mean AMO (±SD) in the normal hip was 33.8 mm (±1.6), the mean ASO (±SD) was 14.3 mm (±1.6), and the mean AAO (±SD) was 1.2 mm (±1.1). the mean AMO (±SD) in the implanted hip was 27.5 mm (±1.2), the mean ASO (±SD) was 16.8 mm (±1.8), and the AAO (±SD) was 3.7 mm (±0.9) in THA. There was a significant difference between the unaffected side and the post-THA offset in the AMO, ASO, and AAO groups (p < 0.001, p < 0.001, and p = 0.03 respectively). The difference in mean values between the normal side and the THA side was ΔAMO (±SD)6.3 mm (±1.9), ΔASO (±SD) 2.5 mm (±1.2), and ΔAAO (±SD) 2.4 mm (±1.0). Conclusion: 3D-CT was used to evaluate the acetabular offset by comparing the post-THA and normal hips after unilateral ALS-THA. Under fluoroscopic reaming, the center of rotation of the hip joint moved inward, upward, and backward. Trial Registration: retrospectively registered