Background: Prader-Willi syndrome (PWS) is a rare genetic disorder characterized by obesity, hypotonia, feeding difficulties, obesity, musculoskeletal manifestations including scoliosis, and hip dysplasia (HD). The aim of this study was to characterize the clinical and radiographic evolution of HD in the pediatric PWS population.
Methods: The authors performed a retrospective cohort study of 72 patients (147 anteroposterior pelvic radiographs) between January 2004 and December 2016. Center-edge angle (CEA) of Wiberg, acetabular index (AI), and neck-shaft angle (NSA) were measures in all hips. The relationship between radiographic and demographic parameters of age, sex, and body mass index z-score (BMIzs) were assessed.
Results: A total of 274 radiographic measurements were performed and analyzed in 72 patients. The mean CEA, AI, and NSA were 21.8±7.1 degrees (range, 5 to 35 degrees), 16.7±7 degrees (range, 5 to 45 degrees), and 142±8.5 degrees (range, 128 to 165 degrees), respectively. HD was diagnosed in 79 (29%) hip radiographs and varied significantly between the age groups (P<0.01). A statistically significant association was identified between age and CEA [β coef, 0.80; 95% confidence interval (CI), 0.6-1; P<0.01], AI (β coef, -0.90; 95% CI, -1.1 to -0.7; P<0.01), and NSA (β coef, -1.11; 95% CI, -1.4 to -0.9; P<0.01) angles. Sex and BMIzs were not identified as independent predictors of radiographic hip angles (P>0.1).
Conclusions: The present study demonstrated favorable evolution of hip radiographic parameters in the PWS population treated with growth hormone early in development. This finding should prompt orthopedists to consider observation alone in the management algorithm for HD in patients with PWS.
Levels of evidence: Level III-a retrospective comparative study.