Ischio-pubic stress fracture after peri-acetabular osteotomy in patients with hip dysplasia

Ischio-pubic stress fracture is one of the potential complications after peri-acetabular osteotomy (PAO) in patients with hip dysplasia. The purpose of this study was to examine the prevalence of and risk factors for ischio-pubic fractures following PAO. A total of 296 hips in 275 patients who underwent transposition osteotomy of the acetabulum between 2001 and 2012 were retrospectively reviewed. Patient characteristics and radiographic parameters were compared between patients with and without fracture. Fourteen ipsilateral hips (4.7 %) in 14 female patients had fracture of the inferior pubic ramus (11 hips) or the ischial ramus (three hips) on the same side as the surgery at an average of 4.6 weeks after PAO. Multivariate analysis indicated that younger age at operation (odds ratio of 1.43 per five years, p = 0.0169) and greater degree of correction (odds ratio of 1.98 per five degrees, p = 0.0005) were significantly associated with ischio-pubic fracture as independent risk factors. All fractures healed conservatively with partial weight-bearing. Younger female patients and greater deformity corrections increased the risk of ischio-pubic stress fracture after PAO.