Bone Abstracts

Background: Prader Willi syndrome (PWS) is a genetic disorder characterized by severe hypotonia in infancy, hypogonadism, dysmorphic features, early onset obesity and mild mental retardation.

Although hip dysplasia occurs in 10–20% in patients with PWS, hip dislocation requiring surgery is seen rarely. To our knowledge, surgical treatment of hip dislocation in PWS has not been reported before.

We present a case with PWS and hip dislocation and describe the challenges during treatment.

Presenting problem: A two years old boy presented to the Pediatric Orthopedic Clinic with a history of waddling gait. The hypotonia and the micro genitalia led to the diagnosis of PWS at age 1.5 month The genetic test revealed SNRPN gene methylation. On physical examination the patient was obese (BMI-S.D. score: +4.5), he had typical facies with frontal narrowing and almond-shaped eyes, small hands, esotrophia and bilateral cryptorchidism with small penis. The x-ray of pelvis showed left hip dislocation. Hypotonia, mental retardation and severe obesity may cause problems including skin necrosis, prolonged wound healing and re-dislocation after surgical treatment of hip dislocation.

Clinical management: The patient underwent open reduction, modified inverted U capsuloplasty and modified Salter osteotomy. The techniques were described previously by AE¹ After the operation the patient had a hip-spica cast to keep the hips in extension, abduction and neutral rotation. This position prevented skin necrosis. Since the patient was mentally retarded, the cast was replaced with bilateral short leg cast with abduction bar. The latter was kept for 2 months. After 2 years of follow up the patient is walking without limping.

Discussion: This is an unusual case of hip dislocation managed by a new technique. This technique can be considered in patients with severe obesity and mental retardation.

Reference: 1. Eren A, Altintaş F, Atay EF, Omeroğlu H. A new capsuloplasty technique in open reduction of developmental dislocation of the hip. J Pediatr Orthop B. 2004 13 139–41.

Disclosure: The authors declared no competing interests.