SLR - December 2018 - Mark J. Sheehan
Reference: Alvarez CM, Wright JG, Chhina H, Howren A, Law P. Botulinum Toxin Type A Versus Placebo for Idiopathic Clubfoot: A Two-Center, Double Blind, Randomized Controlled Trial J Bone Joint Surg Am. 2018 Sep 19;100(18):1589–1596.Scientific Literature Review
Reviewed By: Mark J. Sheehan, DPM
Residency Program: Hoboken University Medical Center, Hoboken, NJ
Podiatric Relevance: Congenital idiopathic clubfoot is a condition shown to affect approximately one out of 1,000 infants. Traditional treatment as first described by Ponseti involves a series of castings to bring the child’s foot into a corrected position. When hindfoot stall occurred and equinus deformity persisted, Ponseti advocated for a percutaneous Achilles tenotomy. Recent studies have advocated for injections of onabotulinum toxin A (BTX-A) into the infant’s gastroc-soleus complex in an attempt to relax the complex, thus avoiding the need for a tenotomy. This study sought to compare the clinical outcomes of BTX-A and placebo injections into the gastroc-soleus muscle at the time of hindfoot stall in infants with idiopathic clubfoot treated with the Ponseti manipulation and cast protocol.
Methods: Patients with congenital idiopathic clubfoot who reached hindfoot stall were evenly randomized into two groups. One group received BTX-A injections into the gastroc-soleus complex, and the second group received an indistinguishable saline solution. Ponseti casting was then continued for four more weeks post injection. Correction was defined as ³ 15° of dorsiflexion with the knee in flexion (DFF) at six weeks post injection. Nonresponders (patients with a DFF < 15°) received a rescue BTX-A injection and underwent weekly manipulation and cast changes for four weeks or until correction. If the clubfoot remained nonresponsive after the first rescue treatment, a BTX-A injection was given and a percutaneous Achilles tendon lengthening at 12 weeks was performed. Recurrence was defined as a loss of response (DFF of <15 ) after 12 weeks of continued response. Primary outcome was the proportion of responders as indicated by a DFF of ³ 15° at two years of age. Secondary outcomes included the proportion of responders at six and 12 weeks.
Results: At six weeks after the injection, 66 percent of the 32 feet that received BTX-A and 63 percent of the 30 feet that received placebo responded to treatment. Seven of 11 patients in the BTX-A arm and all 11 in the placebo arm who had not responded to the first injection responded to a rescue BTX-A injection at six weeks after the first injection. The combined response rate at 12 weeks (first-time responders and patients who did not respond at six weeks but did at 12 weeks) was 88 percent in the BTX-A arm and 100 percent in the placebo arm, resulting in a 94 percent response rate at 12 weeks. At two years of age, 89 percent of the feet continued to respond.
Conclusions: No statistical difference was seen between the BTX-A group and the placebo groups when looking at primary and secondary outcomes of this study. A limitation within the study was crossover of BTX-A injections into the placebo arm at six weeks for nonresponders, making it impossible to know if further correction was due to BTX-A or casting alone. This may indicate that BTX-A rescue injections at six weeks for nonresponders may be an appropriate treatment protocol, but further studies will need to be performed to definitively conclude the efficacy of BTX-A injections as a means of avoiding tenotomy.