Atlas of pathophysiology, 2 Edition

Part II - Disorders

Musculoskeletal disorders


Scoliosis is a lateral curvature of the thoracic, lumbar, or thoracolumbar spine. The curve may be convex to the right (more common in thoracic curves) or to the left (more common in lumbar curves). Rotation of the vertebral column around its axis may cause rib cage deformity. Scoliosis may be associated with kyphosis (humpback) and lordosis (swayback).

Age Alert

About 2% to 3% of adolescents have scoliosis. In general, the greater the magnitude of the curve and the younger the child at the time of diagnosis, the greater the risk for progression of the spinal abnormality. Optimal treatment usually achieves favorable outcome.

Scoliosis may be functional, a reversible deformity, or structural (fixed deformity of spinal column). The most common curve in functional or structural scoliosis arises in the thoracic segment, with convexity to the right. As the spine curves laterally, compensatory curves (S curves) with convexity to the left develop in the cervical and lumbar segments to maintain body balance.

Idiopathic scoliosis, the most common type of structural scoliosis, varies according to age at onset, as follows:

·   infantile—affects mostly male infants between birth and age 3; left thoracic and right lumbar curves

·   juvenile—affects both sexes between ages 4 and 10; no typical curvature

·   adolescent—generally affects girls between age 10 and skeletal maturity; no typical curvature.



·   Poor posture

·   Uneven leg length


·   Congenital—wedge vertebrae, fused ribs or vertebrae, hemivertebrae

·   Paralytic or musculoskeletal—asymmetric paralysis of trunk muscles due to polio, cerebral palsy, or muscular dystrophy

·   Idiopathic—most common; appears in a previously straight spine during the growing years; may be transmitted as an autosomal dominant or multifactorial trait


Differential stress on vertebral bone causes an imbalance of osteoblastic activity. The vertebrae rotate, forming the convex part of the curve. The rotation causes rib prominence along the thoracic spine and waistline asymmetry in the lumbar spine.

Signs and symptoms

·   Backache

·   Lower back pain

·   Fatigue

·   Dyspnea

·   Uneven hemlines or pant legs that appear unequal in length

·   Apparent discrepancy in hip height

·   Unequal shoulder heights, elbow levels, and heights of iliac crests

·   Asymmetric thoracic cage and misalignment of the spinal vertebrae when patient bends forward

·   Asymmetric paraspinal muscles, rounded on the convex side of the curve and flattened on the concave side

·   Asymmetric gait

Diagnostic test results

·   Anterior, posterior, and lateral spinal X-rays, taken with the patient standing upright and bending, confirm scoliosis and determine the degree of curvature and flexibility of the spine.

·   Scoliosiometry measures the angle of trunk rotation.


Mild scoliosis (less than 25 degrees)

·   Observation—X-rays to monitor curve, examination every 3 months

·   Exercise to strengthen torso muscles and prevent curve progression

Moderate scoliosis (30 to 50 degrees)

·   Spinal exercises and a brace (may halt progression but doesn't correct established curvature); braces can be adjusted as the patient grows and worn until bone growth is complete

·   Alternative therapy using transcutaneous electrical nerve stimulation

Severe scoliosis (50 degrees or more)

·   Surgery—supportive instrumentation; spinal fusion in severe cases