Association between total hip arthroplasty following periacetabular osteotomy and acetabular component overhang

Background There is limited understanding of anterior acetabular component overhang, which induces groin pain, in post-periacetabular osteotomy (PAO) hips during conversion to total hip arthroplasty (THA). The aim of the study were to determine the following: (1) the differences in the amount of acetabular component overhang among pre-PAO hips and post-PAO hips in simulating THA; (2) the factors associated with the amount of component overhang in THA following PAO; (3) whether high component placement with elevation of the hip center by 10 mm reduces the amount of component overhang compared to the anatomical component position in THA following PAO. Methods Computer-based simulations of acetabular component implantation were performed using preoperative and postoperative CT data from 30 patients undergoing PAO. Implantation was performed thrice in each patient: in pre-PAO hips (anatomical component position) and post-PAO hips (anatomical and high component position). Component overhang was measured on the axial plane, which passes through the component center. Results Overhang was greater in post-PAO hips [mean (SD) overhang: 5.2 (2.9) mm, pre-PAO hips: 10.2 (4.6) mm, post-PAO hips-mean difference, 5.0 mm; p