ADULT DEFORMITY
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
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.
