Hip Dysplasia in Patients With Hurler Syndrome (Mucopolysaccharidosis Type 1H)

Background: Hip dysplasia is common in patients with Hurler syndrome (HS). However, its prevalence and optimal management is not yet clear because of the rarity of the disease and the prior short life span of these patients. Recent advances in the management of these children using allogeneic hematopoietic cell transplant (HCT) has significantly increased their life expectancy, with many surviving into adulthood. This review was conducted to describe the experience of a single center with hip dysplasia in HS after HCT. Methods: We performed a retrospective review of hip dysplasia in a consecutive series of patients with HS treated with HCT from 1985 to 2008. Results: At 4.5 (+/- 2.9) years after HCT all 51 children (102 hips) with HS showed acetabular dysplasia and proximal femur valgus deformity. Mean age at HCT was 1.6 +/- 0.9 years. Forty hips (39%) underwent hip reconstructive osteotomies at mean age of 6.8 +/- 3.1 years. Significant radiographic improvement was noted in all radiographic parameters at 5.4 +/- 3.7 years after hip surgery (P < 0.001). Acetabular index improved from 33.3 degrees (+/- 7.9) preoperative to 24.7 degrees (+/- 8) after surgery, lateral center edge angle improved from -5.3 degrees (+/- 10.9) to 35.2 degrees (+/- 17.8), migration index from 50.7% (+/- 15.7) to 9.6% (+/- 13.6), and femoral-neck-shaft angle from 150.9 degrees (+/- 5.8) to 130.8 degrees (+/- 12.4). Ten of the 40 hips underwent only proximal femoral varus derotation osteotomy and 30 underwent combined proximal femoral varus derotation osteotomy + pelvic osteotomy. Conclusions: This study reports high prevalence of hip dysplasia (100%) in patients with HS. As significant radiographic improvement was achieved in those patients treated with surgical interventions we recommend annual orthopaedic evaluation of hips in patients with HS after HCT and intervention with reconstructive femoral and pelvic osteotomies for their hip dysplasia.