Is cup positioning easier in DDH patients previously treated with Bernese periacetabular osteotomy?

Acetabular orientation changes after periacetabular osteotomy (PAO) lead to technical change when performing subsequent total hip arthroplasty (THA). There is no unified consensus regarding the solution for acetabular component installation after PAO. In the current study, we performed computed tomography (CT)-based simulation of acetabular component installation and compared the acetabular defect and component position following THA after PAO and the same patient before PAO.

From January 2014 to December 2018, pelvic models of 28 patients (28 hips) underwent PAO and with the risk factors to develop secondary osteoarthritis. The acetabular reconstruction process was simulated using 3D models from CT data, and the acetabular component coverage was calculated in 3D space based on the measurement and algorithm we proposed. We evaluated the anterior, posterior, superior, inferior acetabular sector angle (ASA), the medial wall thickness (MWT), and the distance from the hip center to the plane of pubic symphysis and ossa sedentarium in the study group (post-PAO group) and control group (pre-PAO group). In addition, we investigated the changes in the acetabular component covering and size between the two groups.

A-ASA and I-ASA values were significantly smaller in the post-PAO group than in the pre-PAO group. The S-ASA and distance values were significantly bigger in the post-PAO group. Compared to the pre-PAO group, the post-PAO group has a bone defect in the anterior and inferior medial. However, the post-PAO group has to elevate the cup to improved component coverings.

Acetabular defection following simulation of cup installation after PAO was significantly changed compared to those without PAO. Elevation of hip joint centers as much as 4 mm and increase acetabular cup anteversion were therapeutic options for DDH patients following THA after PAO.