EP1.56 Incidence of Nonunion and Stress Fractures Following Periacetabular Osteotomy: A Systematic Review

Abstract

Periacetabular osteotomy (PAO) is used for treating acetabular dysplasia by reorienting the acetabulum to create greater femoral head coverage. Despite favorable outcomes, complications such as nonunion and stress fractures may impair postoperative recovery. Stress fracture rates vary considerably across studies, and nonunion is often inconsistently defined. To our knowledge, no systematic review has specifically evaluated these complications in detail. The purpose of this study was to determine the incidence of nonunion and stress fractures following PAO. A systematic review was conducted according to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines and was registered in Prospero. PubMed, Scopus, and Cochrane Central Register of Controlled Trials (CENTRAL) were queried in December 2025 using the following search terms: “periacetabular,” “osteotomy,” “fracture,” “stress,” and “nonunion.” Primary research studies reporting incidence of stress fractures and/or nonunion following PAO were included. Two reviewers independently screened studies and extracted data, with discrepancies resolved by a third reviewer. Extracted variables included demographics, nonunion incidence, and stress fracture incidence. Forty-six studies comprising of 8,919 hips were included in the review. Among 45 studies reporting sex, there were 1,095 male hips and 7,237 female hips. The mean patient age ranged from 10.7 ± 1.8 to 42.4 ± 11.2 years. Forty-four studies reported an overall nonunion rate ranging from 0% to 47.6%. Twenty-seven studies reported an overall stress fracture rate ranging from 0.2% to 21.3%. The most commonly reported nonunion sites were the pubis (34 studies) and ischium (18 studies). The most commonly reported stress fracture sites were the inferior pubic ramus (9 studies) and posterior column (9 studies). There was substantial variability in reported nonunion and stress fracture incidence following PAO, likely due to differences in assessment protocols and reporting practices across studies. The pubis and ischium were the most commonly reported areas of nonunion. Clinical relevance of nonunion and stress fractures has not been well established. Standardized routine surveillance and consistent reporting are necessary to reduce heterogeneity.