The prevalence and surgical outcome of Hip Dysplasia in children with Prader-Willi Syndrome

Abstract Background Prader-Willi syndrome (PWS) is a rare disease. Orthopedic-related diseases of PWS include scoliosis, hip dysplasia, osteoporosis, genu valgum, and foot deformities. Limited literature exists on the prevalence, diagnosis, and surgical management of hip dysplasia (HD) in PWS. This study aims to assess the prevalence of hip dysplasia in children with PWS and to evaluate the outcomes following surgical intervention. Materials and Methods A retrospective analysis was conducted on patients diagnosed with PWS at our institution from January 2017 to December 2021. Only those with a genetic confirmation of PWS and an anteroposterior (AP) pelvic radiograph were included. Patient demographics were collected, and the acetabular index (AI) was measured. For children over five years of age, the central edge angle (CEA) was also recorded. A single fellowship-trained pediatric orthopedic surgeon determined the presence of HD based on radiographic measurements. Patients who underwent surgery were followed up for a minimum of 12 months. Results Among the 178 patients with PWS (100 males and 78 females), 99 had AP pelvic radiograph, of which 33 met the criteria of HD, with a prevalence of 33.3%. There was no significant association between prevalence and sex (P = 0.769) or genetic subtype (P = 0.574). The mean age at the time of diagnosis was 34.4 months (6 months to 109 months). Five patients (2 right side, 3 bilateral) underwent surgical intervention, including Salter innominate osteotomy, proximal femoral osteotomy, and close/open reduction of the hip, at an average age of 82.4 months. One patient (2 hips) was lost to follow-up 1.5 months post cast removal. There was a statistically significant improvement in AI from preoperative (42.8 ± 5.9 degrees) to postoperative (21.7 ± 7.7 degrees) measurements (P = 0.003). One hip resulted in stiffness with a flexion of 60 degrees, while the others showed good mobility. No serious postoperative complications were reported during the follow-up. Conclusions The present study demonstrated a higher prevalence of hip dysplasia in patients with PWS than in the general population. The prevalence does not significantly differ across sexes or genetic subtypes. Surgical treatment could reach a similar results as to those of hip dysplasia without PWS.