UPDATE OF HURLER SYNDROME

Abstract

Hurler syndrome is an autosomal recessive metabolic storage disease, with specific musculoskeletal abnormalities termed dysostosis multiplex. Haematopoietic Stem Cell Transplant (HSCT) increases life expectancy, but its effects on the progression of dysostosis multiplex are less certain. We detail the ongoing follow up of 23 patients (range 2.6 – 20.7 years) at a mean of 8.5 years after successful HSCT, the largest series reported in the literature to date.

All patients were clinically examined at an annual multidisciplinary clinic, and serial radiological studies were reviewed to assess development and management of hip dysplasia and genu valgum.

All patients demonstrated characteristic acetabular dysplasia and failure of ossification of the superolateral femoral head. Thirteen patients have undergone hip containment, including eight bilateral combined pelvic osteotomy and femoral derotation, at a mean of 4.4 years. Mean preoperative acetabular angle was 34 ± 5°. Long term follow up of older patients (> 8 years, mean 9.9 years after surgery) demonstrated adequate femoral head cover, with mean centre-edge angle of 40 ± 5° (range 32 – 48°). More recently, isolated innominate osteotomy has been used.

Genu valgum of variable severity due to failure of ossification of the lateral aspect of the proximal tibial metaphysis was more variable, and seven patients underwent medial epiphyseal stapling at a mean of 7.8 years, decreasing tibiofemoral angle by a mean of 7°. Staple dislodgment, however, was seen in four children. All patients remain independently mobile, but hip stiffness and valgus knees contribute to the early fatigue and hip discomfort seen in older children.

Based on our series, we conclude that hip containment surgery has been successful at least into early adolescence, with overall mobility being well preserved. We recommend plating of the proximal tibial epiphysis. Further follow up will monitor the effectiveness of orthopaedic intervention.