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Topic:

Spinal Muscular Atrophy

Issue:

Hip

Category:

Congenital

Title:

Hip Displacement in Spinal Muscular Atrophy: The Influences of Genetic Severity, Functional Level, and Disease-modifying Treatments

Author:

Ulusaloglu, Armagan C. MD; Asma, Ali MD; Shrader, M. Wade MD; Scavina, Mena T. DO; Mackenzie, William G. MD; Erb, Amanda PT; Howard, Jason J. MD

Journal:

Journal of Pediatric Orthopaedics

Date:

March 2024

Reference:

44(3): p e226-e231, DOI: 10.1097/BPO.0000000000002595

Level Of Evidence:

IV

# of Patients:

82

Study Type:

Retrospective cohort study

Location:

Not specified

Summary:

This study investigates the prevalence of hip displacement (HD) in children with spinal muscular atrophy (SMA) and identifies risk factors, including genetic severity, motor function, and disease-modifying agents (DMA).

Methods:

Retrospective cohort of children with SMA who presented between January 2005 and August 2021. Patients had at least one hip radiograph and a minimum 2-year follow-up. Primary outcome: Prevalence of HD (migration percentage ≥40%). Secondary outcomes: SMA type (I, II, III), survival motor neuron 2 copy number, Hammersmith Functional Motor Scale (HFMS), ambulatory status, scoliosis, and DMA treatment (nusinersen/risdiplam/onasemnogene abeparvovec). Statistical analyses: Univariate and multivariate logistic regression.

Exclusions:

None specified

Results:

75.6% of patients had HD, with a mean age of onset of 4.6 years. Prevalence and age of onset varied by SMA type: Type I: 84% prevalence, onset at 3.1 years Type II: 80% prevalence, onset at 5.8 years Type III: 36% prevalence, onset at 9.0 years HFMS score >23 was protective against HD. Univariate analysis showed significant risk factors: SMA type I and II, HFMS ≤23, nonambulatory status, clinically relevant scoliosis, and DMA treatment. Multivariate analysis found SMA type II (P=0.04) and scoliosis (P=0.04) as independent risk factors for HD.

Conclusions:

The prevalence of hip displacement in SMA is highly correlated with disease severity. Risk factors for HD include SMA type, low HFMS scores, nonambulatory status, and clinically relevant scoliosis. Identifying these factors can help develop surveillance programs for early detection and management of HD in SMA patients.

Relevance:

Limitations:

Perspective:

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