Highlights
- •Low BMD was highly prevalent in SMA patients, regardless of SMA subtype.
- •Lateral distal femur BMD declined over time for all SMA subtypes.
- •All SMA subtypes had high fracture frequency with predominance of femur fractures.
- •Time to first fracture was not different among SMA subtypes, although SMA1 patients tended to be younger.
- •Despite fractures and low BMD, few SMA patients met the criteria for osteoporosis.
Abstract
Patients with Spinal Muscular Atrophy (SMA) are at risk for poor bone health. The
prevalence of fractures, low areal bone mineral density (aBMD; Z-score ≤−2.0) of the
lateral distal femur and of osteoporosis by SMA subtype is not known. We aimed to
describe the natural history of bone health in patients with SMA prior to bisphosphonate
treatment. We reviewed data from 85 eligible patients with SMA ages 12 months to 18
years, seen at a single institution between January 2005 and July 2016. Fracture history
was reported at annual clinic visits. aBMD was obtained from dual energy x-ray absorptiometry
scans of the lumbar spine, total body, and lateral distal femur. 85% of patients had
aBMD Z-scores ≤−2.0 SD and were progressively lower with worsening SMA severity. Longitudinal
aBMD Z-scores of the lateral distal femur decreased with age. Fractures occurred in
38% (32/85) of patients with the femur being the most common location (25 of 57 fractures).
Thirteen percent of patients fulfilled criteria for osteoporosis. Low aBMD and femur
fractures are highly prevalent in all SMA subtypes from a young age; however, few
patients met the criteria for osteoporosis. Poor bone health may be an under-recognized
comorbidity of SMA.
Keywords
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Article info
Publication history
Published online: February 01, 2017
Accepted:
January 23,
2017
Received:
September 29,
2016
Identification
Copyright
© 2017 Published by Elsevier B.V.
