Scoliosis describes a sideways curvature of the spine, where the backbone deviates from its natural straight alignment. Assessing the degree of spinal curvature is important for monitoring the condition and guiding management strategies.
Measuring Spinal Curvature
Scoliosis severity is measured using the Cobb angle, a standardized technique developed by Dr. John Robert Cobb in 1948. This measurement is obtained from a standing X-ray of the spine. To determine the Cobb angle, a doctor identifies the most tilted vertebra above and below the apex of the spinal curve.
Lines are drawn parallel to the top of the superior tilted vertebra and the bottom of the inferior tilted vertebra. Perpendicular lines are extended from these parallel lines until they intersect, and the angle formed at their intersection is the Cobb angle, measured in degrees. This angle allows healthcare professionals to track changes over time and inform treatment decisions. While the Cobb angle is widely used, it is a two-dimensional measurement of a three-dimensional spinal condition, and small variations in measurement technique can lead to differences of up to 5 degrees.
Understanding Severity Levels
Based on the Cobb angle measurement, scoliosis is classified into severity categories. A curve measuring between 10 and 25 degrees is considered mild scoliosis. At this stage, the spinal deviation is subtle and may not cause noticeable symptoms.
Moderate scoliosis is characterized by a Cobb angle between 25 and 40 degrees. Curves in this range may become more noticeable and, in adults, can lead to increased pain or postural changes. When the Cobb angle exceeds 40 degrees, the condition is classified as severe scoliosis. Curves greater than 50 degrees can progress steadily, and those over 70 degrees carry a greater risk of affecting heart and lung function due to rib cage twisting.
Factors in Curve Progression
Several factors influence whether a scoliosis curve will worsen over time, regardless of its initial severity. Skeletal maturity, often assessed by the Risser sign, is a predictor; younger individuals with more growth remaining have a higher chance of curve progression. For instance, children 10 years or younger with a curve between 20-29 degrees have nearly a 100% chance of progression, a rate that decreases with age.
The magnitude of the curve at diagnosis also plays a role, with larger initial curves having a greater likelihood of progression. Certain curve patterns or locations are more prone to worsening, such as thoracic curves and double major curves involving both thoracic and lumbar regions. Female individuals have a higher rate of curve progression compared to male individuals, with girls being 10 times more likely to experience progression for curves greater than 30 degrees. Understanding these factors helps in predicting the natural course of the condition and in making informed monitoring decisions.
Treatment Decisions Based on Severity
Treatment recommendations for scoliosis are directly influenced by the assessed Cobb angle and the estimated risk of curve progression. For mild curves, under 25 degrees, the approach involves observation and regular monitoring to determine if the curve is progressing. This includes periodic examinations, every six months.
When curves reach a moderate level, between 20-40 degrees, especially in growing individuals with skeletal growth remaining, bracing may be recommended. Bracing aims to prevent further progression of the curve and stabilize the spine. For severe curves, exceeding 40-50 degrees, or those that continue to worsen despite bracing, surgical intervention might be considered. Surgical goals involve stabilizing the spine and reducing the degree of curvature, with procedures like spinal fusion.