Scoliosis is a condition characterized by an abnormal lateral curvature of the spine, most frequently developing in adolescents during their growth spurt. For moderate curvatures, a spinal brace is the most common non-surgical intervention prescribed by physicians. The goal of bracing is to influence spinal growth and prevent the curve from worsening, helping patients avoid surgical fusion.
Defining Success and Efficacy
The objective of scoliosis bracing is not to completely reverse the existing curvature, but rather to halt its progression until the patient reaches skeletal maturity. Treatment is considered successful if the spinal curve, measured using the Cobb angle, does not progress beyond a certain threshold, typically 50 degrees, which is the point at which surgery is often considered. More specifically, success is often defined in clinical trials as a curve progression of five degrees or less from the initial measurement at the start of treatment. Current clinical evidence strongly supports the use of bracing as an effective treatment modality to prevent progression compared to observation alone, with success rates ranging from approximately 72% to over 85% in skeletally immature patients who wear the brace as prescribed.
The Mechanism of Bracing: How Curvature is Controlled
Rigid spinal braces operate on biomechanical principles, primarily utilizing a three-point pressure system to apply corrective forces to the torso. This system involves applying targeted pressure pads against the convex side of the curve and counter-pressure at two opposite points, effectively pushing the spine toward a straighter alignment. This continuous application of force is designed to modulate the growth of the vertebrae during the adolescent growth spurt, a concept known as “Hueter-Volkmann’s Law.” The pressure applied to the convex side of the curve is thought to slow down the growth on that side, while the release of pressure on the concave side promotes relatively faster growth, thus influencing the spine to grow more symmetrically. Achieving a high degree of “in-brace correction” immediately upon wearing the device is strongly correlated with a greater chance of long-term success in stopping progression.
Types of Braces and Treatment Criteria
Bracing is typically initiated for patients with adolescent idiopathic scoliosis when the Cobb angle falls within a moderate range, generally between 25 and 40 degrees. The patient’s skeletal maturity status, assessed using the Risser sign, is a determining factor, as bracing is most effective for those who still have significant growth remaining. If the curve is less than 25 degrees, close observation is usually recommended, while curves exceeding 45 to 50 degrees are more likely to require surgical intervention.
The most common type is the Thoraco-Lumbo-Sacral Orthosis (TLSO), such as the Boston brace, which is a low-profile, rigid plastic jacket custom-molded to the patient’s torso. This style is often prescribed for full-time wear, typically 18 to 23 hours per day. Alternatively, some patterns of curvature may be treated with night-time braces, such as the Charleston Bending or Providence brace. These braces apply a stronger, more aggressive over-correction force, but only when the patient is lying down, reducing the required wear time to approximately eight to ten hours overnight.
The Role of Patient Compliance
The efficacy of any brace, regardless of its design, is fundamentally dependent on the patient’s adherence to the prescribed wearing schedule. For full-time rigid braces, the goal of preventing curve progression is directly linked to maintaining a wear schedule of at least 16 to 18 hours daily. To address the challenge of adherence, some modern braces are equipped with integrated temperature or pressure sensors to objectively track the actual number of hours the device is worn. These data logging technologies help healthcare providers and families ensure the patient is meeting the necessary compliance requirements for the treatment to be successful.