Spinal Muscular Atrophy

The orthopedic manifestations of spinal muscular atrophy (SMA) primarily involve the hip and spine. The incidence of hip instability is 30–40% and neuromuscular scoliosis is 60–90% in non-ambulatory SMA patients. The intrinsic relationship between hip and spinal deformity often requires concomitant management of the hip and spine to maximize functional and clinical outcomes. This chapter summarizes the nonoperative and operative treatments for joint contractures, hip instability, and spinal deformity as well as the management of bone health in the SMA population. While hip subluxation/dislocation has traditionally been treated nonoperatively in non-ambulatory SMA patients, the intrathecal administration of Nusinersen has changed the functional and ambulatory prognosis of patients with SMA. Thus, clinicians should be aware of both hip and spine monitoring in the SMA population as pediatric orthopedic surgeons are likely to treat progressive hip instability and spinal deformity with operative intervention.