Article: Scoliosis

Scoliosis is a condition that involves complex lateral and rotational curvature and deformity of the spine. It is typically classified as congenital (or infantile), juvenile, adolescent, adult or neuromuscular.

Cause

The cause of scoliosis is poorly understood. There is a clear Mendelian inheritance but with incomplete penetrance. Various causes have been implicated, but none have consensus among scientists as the cause of scoliosis. Scoliosis is more common in females and is often seen in patients with cerebral palsy or spina bifida. In some cases, scoliosis exists at birth due to a congenital vertebral anomaly. Occasionally development of scoliosis during adolescence is due to an underlying anomoly such as a tethered spinal cord, but most often the cause unknown or idiopathic.

Prevalence

Scoliosis curves greater than 10° affect 2-3% of the population. The prevalence of curves less than 20° is about equal in males and females. Curves greater than 20° affect about 1 in 2500 people. Curves convex to the right are more common than those to the left, and single or 'C' curves are slightly more common than double or 'S' curve patterns. Males are more likely to have infantile or juvenile scoliosis, but there is a high female predominance of adolescent scoliosis. Girls are seven times more likely than boys to develop a significant, progressive curvature. Females are nine times more likely to require treatment than males as they tend to have larger, more progressive curves.

Symptoms

Those with scoliosis often do not have pain as adolescents and young adults. Pain is common in adulthood if left untreated. The most common complaint from parents and patients is cosmetic deformity.

The symptoms of scoliosis are:

• Prominent shoulder blade--due to rotational deformity of the spine.
• Muscle mass that causes a "hump" on one side of the spine
• A rib "hump"
• Uneven hip and shoulder levels
• Asymmetric size or location of breast in females
• Unequal distance between arms and body
• Clothes that do not "hang right"

Associated conditions

Scoliosis is often associated with other conditions such as cerebral palsy, spinal muscular atrophy, Friedreich's ataxia); skeletal dysplasias; Marfan's syndrome; neurofibromatosis; connective tissue disorders; and craniospinal axis disorders (e.g., syringomyelia).

However, the majority of patients with scoliosis have no other abnormalities.

Investigation

Cobb angle measurement in scoliosis

Those suspected of having scoliosis should undergo a thorough physical examination.

During a physical examination, the following should be assessed:

• Skin for café au lait spots indicative of neurofibromatosis
• The feet for cavovarus deformity
• Magnitude of the curve and rib hump both while standing and while leaning forward
• Asymmetric shoulder and breast levels
• Asymmetric superficial abdominal reflexes
• Inequality of lengths of the upper limbs from the floor when leaning forward

During the exam, the patient's gait is assessed, and there is an exam for signs of other abnormalities (e.g., dysraphism as evidenced by a dimple, hairy patch, lipoma, or hemangioma). A thorough neurological examination is also performed..

Full-length standing spine X rays are the standard method for evaluating curve severity and progression. Serial radiographs are obtianed at 3-12 month intervals to follow curve progression. In some cases, MRI investigation is warranted.

The standard method for assessing the curvature quantitatively is measurement of the Cobb angle, which is the angle between two lines, drawn perpendicular to the upper endplate of the uppermost vertebrae involved and the lower endplate of the lowest vertebrae involved. For patients who have two curves, Cobb angles are followed for both. In some patients, lateral bending xrays are obtained to assess the flexibility of the curves.

Prognosis

The prognosis of scoliosis depends on the likelihood of progression. The general rules of progression are that larger curves carry a higher risk of progression than smaller curves, and that thoracic and double primary curves carry a higher risk of progression than single lumbar or thoracolumbar curves. In addition, patients who have not yet reached skeletal maturity have a higher likelihood of progression.

Management

The management of scoliosis is complex and is determined by the severity of the curvature, skeletal maturity, and likelihood of progression.

The conventional options are, in order:

1. Observation
2. Bracing
3. Surgery

Bracing is only done when the patient has bone growth remaining. (However, some controversial alternative treatments also advocate bracing of adults for correction; none of these have been subjected to peer-reviewed study, and their efficacy is uncertain.) Bracing involves fitting the patient with a device that covers the torso and in some cases it extends to the neck. The most commonly used brace is a TLSO or Boston Brace, a corset-like appliance from armpits to hips, custom-made from plastic. It is usually worn 23 hours a day and applies pressure on the curves in the spine. In infantile and sometimes juvenile scoliosis a body cast or plaster jacket can be used instead. Bracing is only mildly effective as compliance is typically low, although some of the newer braces (such as the Charleston back brace) are touting better compliance rates and outcomes. Typically braces are only used for small curves as they are unable to correct large curves. The degree of curvature that will respond to bracing is controversial, but it is generally accepted that curves greater than 25-30° are unlikley to respond to bracing although some will remain stable at that degree of curvature.

Chiropractic may also be used to treat scoliosis, though some medical experts disagree on the efficacy of such treatment.

Surgery

Surgery is usually indicated for curves that have a high likelihood of progression, curves that would be cosmetically unacceptable as an adult, curves in patients with spina bifida and cerebral palsy that interfere with sitting and care, and curves that affect physiological functions such as breathing.

Surgery for scoliosis is usually done by pediatric orthopaedic surgeon or by a specialized spine surgeon. Spinal release with spinal fusion is the most widely performed surgery for scoliosis. In this procedure, the ligaments and joints that hold the curve in place are released so that the curve can be corrected. In some patients, this may require accessing the anterior (front) aspect of the spine by entering the chest or abdominal cavity in addition to operating on the spine from the back (posterior). After intra-operative correction of the curvature, the joints of the spine are removed and bone graft, (either harvested from elsewhere on the body, or donor bone) is placed between vertebrae so that when the spinal column heals, it becomes a rigid and straight column. Although this restricts spinal movement, it straightens and prevents worsening of the curve.

Originally, spinal fusions were done without metal implants. A cast was applied after the surgery, usually under traction to pull the curve as straight as possible and then hold it there while fusion took place. Unfortunately, there was a relatively high risk of fusion failure at one or more levels and significant correction could not always be achieved. In 1962 Paul Harrington indtroduced a metal spinal system of instrumentation which assisted with straightening the spine, as well as holding it rigid while fusion took place. The original, now obsolete Harrington rod operated on a ratchet system, attached by hooks to the spine at the top and bottom of the curvature that when cranked would distract, or straighten, the curve. Modern spinal systems involve a combination of rods, screws, hooks and wires fixing the spine and can apply stronger, safer forces to the spine than the Harrington rod.

Recently, new implants have been developed that aim to delay spinal fusion and to allow more spinal growth. These include rods that are extendable and allow growth, ribcage implants that push apart the ribs on the concave side of the curve, and vertebral stapling which is a method of retarding normal growth on the convex side of a curve, allowing the concave side to 'catch up'. Although these methods are novel and promising, spinal fusion remains the 'gold-standard' of surgical treatment for scoliosis.

Modern spinal fusions generally have good outcomes with high degrees of correction and low rates of failure and infection. Patients with fused spines and permanent implants tend to have normal lives with unrestricted activities. They are able to participate in recreational athletics, have natural childbirth and are generally satisfied. The most notable limitation of spinal fusions is that patients who have undergone surgery for scoliosis are ineligible for military service in the United States.