The purpose of this six site multi-center study is to determine if BTX-A can alleviate the post-operative pain and improve the functional and quality of life outcomes of children with limb length discrepancy or angular deformity undergoing limb lengthening or deformity correction.

The specific aims are to determine if BTX-A will:

• 1a. Reduce pain post operatively and during the distraction and consolidation process,
• 1b. Reduce the amount, frequency and duration of narcotics taken in the postoperative period.
• 2. Improve the quality of life during the distraction and consolidation process.
• 3 Decrease muscular spasm and subsequent muscle contracture during the distraction and consolidation process and accelerate earlier return to pre-operative mobility function including earlier weight bearing.
• 4. To develop clinical practice guidelines for the interdisciplinary care of children undergoing limb lengthening or deformity correction.

Methodology: A randomization process for this one time injection will be used to determine who will receive the BTX-A or the placebo. 150 subjects will be recruited; 75 to the BTX-A group and 75 to the placebo group. There will be an equal number of subjects in each group at each site. The medication will be injected intraoperatively into specific major muscles in the lower limb adjacent to the bone or soft tissue being lengthened or corrected at a dose of 10 U/kg with a maximum of 50 U per site, not to exceed a total maximum dose of 400 units. Pain scores, medication dosages, range of motion and an ambulation scale will be measured post-operatively and during the distraction and consolidation phases.

In addition families will be asked to complete six different questionnaires related to pain, quality of life and psycho-social issues at various times during the process. The children will receive standard nursing care and physical therapy and will be followed for three months after the external fixator is removed, for a total time of approximately one year.

Inclusion Criteria:

• Age: 5 to 21 years.
• Aetiology of the deformity: congenital or acquired.
• Amount of lengthening or deformity correction: any amount.
• Site of lengthening or deformity correction: lower extremity.
• Type of fixator: circular or uniplanar.

Exclusion Criteria:

• Children younger than 5 years of age.
• Associated neuromuscular conditions that may hinder weight bearing.
• Individuals on aminoglycosides, as aminoglycosides can potentiate the effect of Botulinum toxin A.