Ultrasonographic hip morphology in mucopolysaccharidosis type I Hurler after hematopoietic stem cell gene therapy

Purpose: To assess ultrasonographic features of hip morphology in mucopolysaccharidosis type I Hurler. Methods: Acetabular bony rim, acetabular cartilaginous roof, alpha and beta angles, echogenicity, and hip coverage were analyzed in eight mucopolysaccharidosis type I Hurler syndrome children before and after hematopoietic stem cell gene therapy. Results: Sixteen hips at baseline, 10 at +12 months, and 10 at + 24 months after hematopoietic stem cell gene therapy were evaluated. The median age was 22, 35, and 45 months at baseline evaluation, +12, and +24 months, respectively. Acetabular bony rim at baseline was angular in 2/16, rounded in 10/16, notched in 2/16, and flattened in 2/16; at +12 months, angular in 2/10, rounded in 5/10, notched in 3/10; at +24 months, angular in 2/10, rounded in 3/10, irregular in 1/10, and notched in 4/10. Acetabular cartilaginous roof at baseline was normal in 4/16, enlarged in 12/16; at +12 months, enlarged in 10/10 and at +24 months, enlarged in 8/10 and normal in 2/10. Echogenicity of the joint capsule at baseline was normal in 10/16, increased in 6/16; at +12 months, normal in 8/10, increased in 2/10; at +24 months, normal in 6/10, increased in 4/10. The mean femoral head coverage was 60% at baseline (16/16), 62% at +12 months (10/10), and 52% at +24 months (2/10). The mean alpha angle was 60° at baseline (16/16), 64° at +12 months (10/10), and 60° (2/10) at +24 months. The mean beta angle was 67° at baseline (16/16), 65° at +12 months (10/10), and 49° at +24 months (8/10). Conclusions: Hip morphology of children with mucopolysaccharidosis type I Hurler syndrome before and after hematopoietic stem cell gene therapy can be evaluated by available ultrasound techniques until a median age of 45 months.