Scoliosis is a condition characterized by a lateral curvature of the spine, often accompanied by vertebral rotation. This spinal deformity is most frequently diagnosed in adolescents, and while the curve is typically mild, it can sometimes worsen during periods of rapid growth. Bracing is a common non-surgical intervention prescribed by orthopedic specialists to manage this progression. The purpose of bracing is not to correct the existing curve, but to halt or slow its increase while the patient is still developing. Specialists use specific, measurable criteria to determine when bracing is necessary, focusing on the degree of the curve and the patient’s remaining growth potential.
Cobb Angle: The Primary Measurement
The primary measurement used to assess scoliosis severity is the Cobb angle, which quantifies the spinal curve magnitude in degrees on an X-ray. It is determined by drawing lines parallel to the top and bottom vertebrae of the curve and measuring their intersection angle. A Cobb angle of 10 degrees or more is required for a formal diagnosis of scoliosis.
The Cobb angle serves as the initial trigger for treatment decisions, categorizing the curve into mild, moderate, or severe ranges. Curves under 20 degrees are considered mild and managed through close observation and regular monitoring. Bracing is recommended for moderate curves (25 to 40 degrees), especially if the patient is still growing.
A curve that increases by 5 degrees or more over a monitoring period, regardless of its initial size, is considered progressive and often warrants bracing. For example, a younger patient with a 20-degree curve that progresses to 25 degrees within six months would be a strong candidate for a brace. Curves measuring 45 to 50 degrees or greater are considered severe. At this magnitude, the risk of continued progression after growth is high, making surgical correction the more likely treatment option.
Skeletal Maturity: The Growth Factor
Remaining growth potential is the second most important factor, as bracing is only effective while the spine is actively growing. Without growth, the forces applied by the brace cannot influence the spine’s development. Doctors assess skeletal maturity to predict the risk of curve progression, which is highest during the adolescent growth spurt.
Skeletal maturity is assessed using the Risser sign, a classification system based on the appearance of the iliac apophysis (the growth plate on the hip bone) seen on a pelvic X-ray. The Risser sign is graded on a scale from 0 to 5, representing the degree of fusion of this growth plate. A Risser score of 0, 1, or 2 indicates a high risk of curve progression because the patient has significant growth remaining.
A Risser score of 0 or 1 suggests the patient is in the peak window of growth, making bracing necessary for moderate curves to prevent worsening. In contrast, a Risser score of 4 or 5 signifies near or complete skeletal maturity. A 30-degree curve in a patient with a Risser 5 is less likely to progress and may not require bracing, whereas the same curve in a patient with a Risser 0 is at a much greater risk and would necessitate immediate intervention.
Bracing Goals and Compliance
The goal of bracing is stabilization: preventing the curve from progressing past the surgical threshold of 45 to 50 degrees. Bracing does not typically correct the existing curvature, but rather holds it steady until the patient finishes growing. The Boston brace, a common rigid orthosis (TLSO), applies pressure to the spine to guide its growth.
Bracing success is directly linked to patient compliance (the number of hours the brace is worn daily). For maximum effectiveness, full-time bracing requires wearing the orthosis for a minimum of 16 to 18 hours per day, though some specialists prescribe up to 23 hours. Consistent wear is crucial because the corrective pressure must be sustained to counteract the forces that drive the curve’s progression during growth.
Thermal sensors are sometimes built into the brace to monitor wear time, providing objective data for the care team. Patients who wear their brace for the prescribed number of hours have a significantly higher rate of successful curve management compared to those with lower compliance. The full-time commitment to brace wear, even with breaks for sports and showering, is a demanding aspect of the treatment that requires strong support from the patient and family.
Determining When Bracing Ends
Brace treatment continues until the spine is no longer vulnerable to progression from growth, marking the end of stabilization. The decision to discontinue bracing is based on a combination of factors related to the patient’s skeletal maturity and curve stability. The most definitive indicator is reaching complete skeletal maturity, defined as a Risser score of 4 or 5 on the pelvic X-ray.
For female patients, another clinical marker is the time passed since the onset of menses, with bracing continuing for one to two years after this event. The spine curvature must also demonstrate stability, meaning it has not progressed beyond a certain threshold for a specified period. Once these criteria are met, the patient is often transitioned into a gradual weaning process.
Weaning involves progressively reducing the number of hours the brace is worn each day over several months, rather than stopping abruptly. This step allows the spine and surrounding muscles to adjust to being unbraced without the risk of an immediate, rapid curve progression. Completion of bracing signifies that the patient has navigated the period of highest risk and the curve is stable enough to be monitored without daily intervention.