SLR - September 2016 - Bryon McKenna

AbobotulinumtoxinA for Equinus Foot Deformity in Cerebral Palsy: A Randomized Controlled Trial

Reference: Delgado MR, Tilton A, Russman B, Benavides O, Bonikowski M, Carranza J, Dabrowski E, Dursun N, Gormley M, Jozwiak M, Matthews D, Maciag- Tymecka I, Unlu E, Pham E, Tse A, Picaut P. AbobotulinumtoxinA for Equinus Foot Deformity in Cerebral Palsy: A Randomized Controlled Trial. Pediatrics. 2016 Feb;137(2):e20152830.

Scientific Literature Review

Reviewed By: Bryon McKenna, DPM
Residency Program: Mount Auburn Hospital

Podiatric Relevance: The foot and ankle surgeon plays a role in the management of patients with cerebral palsy due to the pedal deformities that are often associated with this diagnosis. The most common pedal deformity associated with cerebral palsy is equinus, associated with spasticity of the gastrosoleus muscle complex. Treatment of the spastic equinus deformity with botulinum toxin A was first described in literature by Koman et al. in 1993 and has been a common practice since. This study fills a large gap in the scientific evidence required to support this treatment modality. This study provides recommended dosages and methods for injection for this treatment. It is critical for the foot and ankle surgeon to ensure that this conservative treatment option is attempted prior to proceeding to more advanced surgical options as recommended by clinical guidelines.

Methods: This study was a phase III, international, double-blind, multicenter, randomized control trial. The study included 241 subjects who were randomized into three treatment groups, placebo (N=81), abobotulinumtoxin A 10 U/Kg/leg (N=80) and abobotulinumtoxin A 15 U/Kg/leg (N=80). Only pediatric subjects (age 2–17) with spastic paresis, ambulatory and diagnosed with equinus deformity were included. Muscle tone and spasticity were assessed using the MAS and Tardieu scales. Patient functionality was assessed using the Physician’s Global Assessment (PGA) and goal attainment scaling (GAS). Treatment-emergent adverse events were recorded at each visit. The primary end point was defined as change in the MAS from baseline to week 4 after treatment.

Results: Of the 241 subjects who were randomized in the trial, 226 completed the trial, one patient in the placebo group prematurely terminated due to an adverse event (the specifics of which were not reported) and 235 subjects were included in the intention to treat population. The MAS significantly improved in both Abobotulinum toxin groups. The adjusted mean treatment difference compared to placebo was -0.49 (-0.75 to -0.23; p <0.001) for 15 U/Kg and -0.38 (-0.64 to -0.13; p=0.003) for 10 U/Kg groups. The PGA treatment difference compared to placebo was 0.77 (0.45 to 1.10) for 15 U/Kg and 0.82 (0.50 to 1.14) for 10 U/Kg groups. There were two treatment-related, treatment-emergent adverse events reported by >2 percent of patients, pyrexia and local muscle weakness.

Conclusions: This randomized study shows marked improvement in muscle tone and functionality in pediatric patients with cerebral palsy with a single injection of abobotulinumtoxin A. Clinical guidelines now recommend that BoNT-A should be offered as an effective, well-tolerated, localized treatment for equinus deformity in cerebral palsy, but this study helped further provide scientific evidence as to the effectiveness of this therapy and further justify its clinical use. 

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