SLR - December 2018 - Mark J. Sheehan
Botulinum Toxin Type A Versus Placebo for Idiopathic Clubfoot: A Two-Center, Double Blind, Randomized Controlled Trial
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.
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.