Bone Health Status of Children with Spinal Muscular Atrophy.

BACKGROUND

Spinal muscular atrophy (SMA) is a group of rare, inherited neuromuscular disorders. Bone health is often a neglected issue in children with SMA. This study aimed to evaluate the bone health status of children with SMA in Hong Kong.

METHODS

This retrospective study included children with SMA who were managed in the Neuromuscular Disorder Clinics of 2 quaternary centers in Hong Kong. Bone health status was assessed by fracture history, bone mineral density (BMD) measured by dual energy X-ray absorptiometry, and serum 25-hydroxy-vitamin D (25[OH]D) level.

RESULTS

Thirty-two children were included (males, 12). The median age was 10.8 years. BMD assessments were performed in 17 patients (SMA type 1=2, type 2=8, type 3=7). Low BMD was observed in 16 out of 17 patients. Four had a history of long bone fractures and were started on bisphosphonates. SMA types, age at last visit, sex, ambulation, and 25(OH)D level were not associated with fracture history or BMD Z-scores. Only one fulfilled the 2019 International Society for Clinical Densitometry (ISCD) pediatric definition of osteoporosis, with both low BMD and a history of clinically significant fracture.

CONCLUSIONS

Children with SMA on disease-modifying treatments commonly had Low BMD and a history of fractures, but osteoporosis was uncommon according to the 2019 ISCD pediatric definition. A special definition of osteoporosis may be needed for this high-risk group.