This study evaluates the combined effect of botulinum toxin A (administered as Dysport® (Ipsen Pharmaceuticals)) and bracing in children with adolescent idiopathic scoliosis. Two thirds of patients will be treated with Dysport® and bracing, while the remaining patients will be treated with placebo and bracing.

Adolescent idiopathic scoliosis (AIS) is lateral curvature of the spine with an unknown cause in children 10-16 years old. Without treatment, skeletally immature children with idiopathic curves of 20°-40° risk curve progression. Treatment of these patients is focused on either observation or bracing. Although bracing has been shown to be more effective than observation, success is contingent on patient adherence and has the potential for further optimization with adjunct therapies.

Little research is available concerning adjunct therapies that may be used during bracing of AIS patients. One therapy in particular, abobotulinumtoxinA (BTX) injection, has been poorly studied. Injection of BTX into the paraspinal musculature of the concave aspect of the major curve may result in a more malleable curve and thus optimize brace treatment. If BTX injections are found to improve outcomes in this way, a new standard of nonoperative care could be established for AIS patients, potentially reducing the number of patients who undergo surgery.

The aim of this study is to assess whether BTX injections (administered as Dysport® (Ipsen Pharmaceuticals)) in the paraspinal musculature at the site of the major scoliotic curve decrease curve progression in skeletally immature AIS patients who are concurrently treated with bracing. Dysport® will be evaluated primarily as an adjunct treatment to bracing.

Hypotheses

1. Dysport® injections into the concave-side paraspinal muscles will decrease the rate of curve progression, with a lower rate of curve progression in patients treated with both Dysport® injections and bracing compared with those treated with only bracing.
2. Quantitative physical and mental health scores will improve to a greater extent in patients treated with Dysport® and bracing compared with patients treated with only bracing.

Inclusion criteria:

• Clinically determined idiopathic nature of scoliosis
• Age 10-16 years
• Risser stage 0,1,or 2
• major curve of 20°-40°
• curve apex caudal to T7 vertebra
• ability to adhere to bracing protocol
• Botulinum toxin naïve or previously treated greater than 6 months prior to study entry

Exclusion criteria:

• Diagnosis of congenital scoliosis, neuromuscular scoliosis, or other "reason" for scoliosis - Previous surgery at any segment of the spine
• Current need for surgery at any level of the spine
• Treatment with any drug known to interfere with neuromuscular function
• Any other medical condition, laboratory or diagnostic procedure finding that might preclude administration of BTX
• Ongoing infection at the injection sites
• Diagnosis as either resistant or sensitive to botulinum toxin treatment of any type or to any components of the BTX formulation
• Cow milk protein allergy