spinal muscular atrophy
A genetic neuromuscular disorder affecting motor neurons, causing progressive muscle weakness and atrophy with significant orthopedic manifestations including scoliosis and contractures.
Full Definition
Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder caused by mutations in the survival motor neuron 1 (SMN1) gene, resulting in progressive degeneration of motor neurons in the spinal cord. The condition is classified into types I-IV based on age of onset and functional abilities, with Type I being the most severe. From an orthopedic perspective, SMA patients develop significant complications including progressive scoliosis, hip subluxation or dislocation, joint contractures, and osteoporosis due to muscle weakness and immobility. Scoliosis in SMA is typically early-onset, rapidly progressive, and often requires surgical intervention with growing rod constructs or definitive spinal fusion. Hip surveillance is crucial as subluxation is common, though the role of surgical intervention remains controversial. Physical therapy, bracing, and positioning are important components of comprehensive care to maintain function and prevent contractures.
Usage
Usage note: Specify SMA type when known; emphasize orthopedic complications in surgical contexts.
In Context
- "The patient with spinal muscular atrophy Type II developed a 60-degree thoracolumbar scoliosis requiring surgical correction." — Surgical consultation note
- "Hip surveillance protocols for spinal muscular atrophy patients include regular radiographic monitoring." — Clinical care guideline