Failed periacetabular osteotomy leads to acetabular defects during subsequent total hip arthroplasty

Background Acetabular wall defects after periacetabular osteotomy (PAO) lead to technical difficulties when performing subsequent total hip arthroplasty (THA). There is no unified consensus regarding the solution for THA socket installation after PAO. In the current study, we performed computed tomography (CT)-based simulation of socket installation and evaluated the acetabular defect following THA after PAO and after primary osteoarthritis (OA). Patients and methods The study group comprised 55 patients (56 hips) who underwent THA after PAO. For the control group, after matching for age, sex, and Crowe classification, we included 55 patients (56 hips) who underwent primary THA for hip dysplasia. We evaluated the anterior, posterior, and superior acetabular sector angle (ASA) and medial wall thickness (MWT) at the anatomical hip center (at the 20-mm vertical hip level from teardrop) in the study group (anatomical PAO group) and control group (primary OA group). In addition, we investigated the changes in the socket covering when the socket was positioned 10 mm above the anatomical hip center (30 mm above the teardrop; elevated osteotomy group). Results All ASA and MWT values were significantly smaller in the anatomical PAO group than in the primary OA group. In particular, the individuals with a Crowe classification of II/III in the anatomical PAO group presented severe acetabular defects. However, the elevated PAO group had a significantly larger ASA compared to the anatomical PAO group, with improved socket coverings. Conclusion Acetabular defects in the anatomical hip center following THA after PAO were significantly common compared to those after primary THA. Elevation of hip joint centers as much as 10 mm is one therapeutic option in the case of severe acetabular defects following THA after PAO.