Mechanical influence of periacetabular osteotomy on late total hip arthroplasty.

Abstract

Periacetabular osteotomy (PAO) is an effective technique to treat symptomatic hip dysplasia. However, following PAO, some patients still experience persistent pain or development of hip arthritis, requiring total hip arthroplasty (THA). Issues such as whether patients with PAO are necessarily at increased risk of post-THA complications and revision of the prosthesis remain debatable. The purpose of this study was to evaluate the biomechanical influence of PAO on the acetabulum after THA by finite element analysis. Eight patients with developmental dysplasia of the hip (DDH) diagnosed in the Fourth Medical Center of the PLA General Hospital were enrolled in this research. Patient-specific hip joint models were reconstructed from computed tomography scans, and the hip prosthesises, were established via computer-aided design (CAD) modeling technology. The finite element analysis was conducted to compare the surface and internal stress through the process mapping of the model due to the THA. Compared with the THA after PAO, the position of the high-stress area of the acetabular fossa of patients without PAO decreased, and the high-stress area developed toward the lower edge of the acetabulum. Although the high-stress area of the suprapubic branch did not change significantly, the peak stress was higher (t=.00237). The analysis of the section plane showed that the high-stress area of cancellous bone had a large distribution. The acetabular size and vertical distance of rotation center (VDRC) were significantly correlated with the maximum postoperative acetabular equivalent stress (p=.011, p=.001). In the Post group, both the horizontal distance of rotation center (HDRC) and A-ASA were significantly correlated with postoperative maximal acetabular equivalent stress, with a significance of 0.014 and 0.035, respectively. The risk of postoperative prosthetic revision following THA is not increased by PAO, although the risk of postoperative suprapubic branch fracture is increased.