Scoliosis is a complex musculoskeletal condition defined by an abnormal, three-dimensional curvature of the spine. This involves not only a sideways deviation but also a rotation of the vertebrae, making it a structural deformity. A common concern is whether the curve will worsen and what specific measurement requires intervention, such as wearing a brace. Understanding the medical criteria used to assess the spine and determine treatment is key to managing the condition.
How Scoliosis is Measured
The standard diagnostic tool used to quantify the severity of a spinal curve is the Cobb angle, determined from a standing X-ray image. A curve is officially diagnosed as scoliosis when the Cobb angle measures 10 degrees or more. To calculate the angle, a physician identifies the most-tilted vertebrae at the upper and lower ends of the curve. Lines are drawn parallel to the endplates of these top and bottom vertebrae. The Cobb angle is the resulting angle created when perpendicular lines are drawn from these two parallel lines until they intersect.
The Standard Bracing Threshold
Medical professionals use the Cobb angle as a primary guide to decide when bracing is appropriate, particularly for adolescents who are still growing. Observation is typically recommended for curves between 10 and 25 degrees, provided there is no rapid progression. Bracing intervention for skeletally immature patients generally begins at 25 degrees and is recommended for curves measuring up to 40 degrees. The main rationale is to prevent the curve from progressing to a magnitude that would necessitate surgical correction. When a curve reaches or exceeds 45 to 50 degrees, surgery often becomes the recommended treatment option.
Individual Factors That Alter the Bracing Decision
The Cobb angle is a numerical starting point, but it is not the sole determinant for a bracing decision. A patient’s remaining growth potential is paramount, as curve progression is most likely during periods of rapid growth. The rate of curve progression is another influential factor that can alter the standard bracing criteria. If a curve is rapidly worsening, such as an increase of 5 or more degrees over a six-month period, intervention may be recommended even for a curve less than 25 degrees.
Assessing Skeletal Maturity (Risser Sign)
Skeletal maturity is assessed using the Risser sign, a grading system from 0 to 5 based on the ossification of the iliac crest seen on an X-ray. A Risser sign of 0 or 1 indicates that the patient has significant growth remaining and is at a high risk for curve worsening. Bracing is most effective for curves in the 25-40 degree range when the patient is in the earlier Risser stages (0 to 2). Conversely, if a patient has a 30-degree curve but a Risser sign of 4 or 5, bracing may not be necessary as the risk of further progression is significantly lower, making intervention less likely.
Overview of Bracing Treatment
Once the decision to brace has been made, treatment focuses primarily on stopping the curve from progressing further, rather than correcting the existing curve magnitude. The brace works by applying external pressure to the torso, influencing the growth of the spine into a straighter position. The success of bracing is directly linked to the patient’s compliance with the prescribed wear schedule. Two common types are the Boston Brace and the Charleston Bending Brace.
Common Brace Types
The Boston Brace is a low-profile Thoraco-Lumbo-Sacral Orthosis (TLSO) typically worn full-time, often for 18 to 23 hours daily. The Charleston Bending Brace is a night-time only brace designed to hyper-correct the curve while the patient is lying down. It is generally reserved for smaller, more flexible single curves located in the lower thoracic or lumbar spine. Consistent wear for the required hours is crucial, as studies indicate a higher compliance rate leads to a significantly lower rate of curve progression.