Scoliosis is a coronal curvature of the spine of more than 10 degrees. In adults, scoliosis either presents as the sequela of adolescent idiopathic scoliosis or develops de novo secondary to degenerative changes in the disc, osteoporosis, or both (see Plates 1-36 to 1-39 for congenital scoliosis). Other less common causes include neuromuscular conditions such as post-traumatic paraplegia.
Curve progression may occur in adults with preexisting adolescent idiopathic scoliosis. Progression is less likely when the curve is less than 30 degrees but occurs more frequently with 50- to 75-degree thoracic curves and unbalanced thoracolumbar or lumbar curves of greater than 30 degrees. Older adults with adolescent idiopathic scoliosis who develop degenerative changes are more likely to have curve progression. Osteoporosis may enhance curve progression in patients with degenerative scoliosis.
Many patients with milder degrees of adult scoliosis are completely asymptomatic. Those with symptoms most commonly report pain localized to the area of curvature. The overall incidence of back pain in adults with scoliosis may not differ from those without scoliosis, but the incidence of severe pain is greater. As with back pain generally, the source of the pain can be difficult to localize and is often multifactorial. Causes include trunk imbalance with subsequent muscle fatigue; overload of facets, discs, and ligaments; and spinal stenosis. Radicular symptoms are more common in patients with degenerative scoliosis because the curve may narrow the neural foramen, particularly in the concavity of the curve. Significant pulmonary compromise from the curve is unlikely unless the patient has a massive (>70-80 degrees) thoracic curve.
Nonoperative management of painful adult scoliosis is similar to management of other chronic spine conditions. Indications for surgical management include structurally significant curves with documented progression, progressive neurologic symptoms, or intractable pain.
Operative management includes decompression for stenotic symptoms and spinal fusion with instrumentation because this facilitates some degree of curve correction and allows for early ambulation. The most important goal of fusion surgery is to restore coronal and sagittal balance (i.e., the head should be positioned over the pelvis in both planes) and to arrest curve progression. In rigid, nonflexible curves, anterior release via discectomy and potentially vertebral osteotomy may be required to achieve correction. The incidence of major complications for deformity surgery is much higher in adults than adolescents. Possible adverse outcomes include pseudarthrosis, persistent pain, neurologic injury, thromboembolism, infection, and, rarely, death.
SAGITTAL PLANE DEFORMITY
Alterations in the normal sagittal alignment of the spine can be a debilitating problem in adults. As with scoliosis, significant sagittal plane malalignment can cause back pain, most likely as a result of disc, ligament, and muscle overload and the need for accessory muscles to combat the deformity and to maintain an erect position. Lumbar kyphosis is among the most common causes of sagittal plane deformity (see Plate 1-27). Aging of the spine is normally “kyphogenic,” with loss of the normal lumbar lordosis. Further sagittal deformity can occur from multiple causes, such as genetic disease like ankylosing spondylitis, metabolic bone disease, and osteoporosis. It can also be caused, or accentuated, by iatrogenic factors, such as fusion using older types of distraction instrumentation (e.g., Harrington rods) or spinal fusion without contouring lordosis into the fusion construct. Kyphosis commonly presents as pain, fatigue, and change in posture. Loss of lumbar lordosis with a kyphotic posture can predispose patients to tripping and easy fatigue while walking and may necessitate the use of a walker or other assistive device that will support a flexed posture. Without such support, hip and knee flexion is frequently required to allow for forward gaze. Stance and gait in this position is extremely fatiguing. The constellation of pain and deformity in patients with lumbar kyphosis has been called “flat back.”
Nonoperative management is similar to that of adult scoliosis. For symptomatic patients with sagittal imbalance, surgery is the mainstay of treatment. This frequently involves an osteotomy in the lumbar spine to recreate lordosis with instrumentation and fusion to maintain the correction. Potential complications of this type of surgery are significant and are similar to those for surgical treatment of adult scoliosis.