Ponseti treatment for clubfoot: Past and future
Talipes equinovarus (clubfoot) is a congenital deformity in which the foot is inclined inward, axially rotated outward and downward pointing. It is one of the most common problems seen in pediatric orthopedics, with incidence rates ranging from 1 in 1,000 live births in the U.S. to about 7 in 1,000 live births among Polynesian Islanders and the Maoris in New Zealand. Males are affected twice as often as females, and the incidence of bilaterality is 50 percent.
A small percentage of cases are associated with a generalized syndrome such as amniotic band syndrome or with neuromuscular disorders, including spina bifida and arthrogryposis, but most are idiopathic. Some studies have suggested that variations in the protein-encoding gene PITX1 or its downstream transcriptional targets may increase susceptibility to clubfoot, but the precise etiology has not yet been identified.
Management then and now
Clubfoot treatment is among the earliest orthopedic therapies; Hippocrates described a method of gentle manipulation and bandaging that is remarkably similar to the approach Ignacio Ponseti, M.D., developed in the 1940s and published in 1963. Ponseti's method, which involves serial casting and percutaneous Achilles tenotomy of the affected foot followed by bracing to maintain the correction, is now the de facto gold standard for clubfoot treatment worldwide.
It was ignored for nearly 40 years, however, when the standard of care was aggressive surgical correction involving tendon lengthening and release of capsular and ligamentous structures. Release procedures, although successful in the short term, frequently demonstrated overcorrection, pain and stiff scar healing on follow-up, and children often required further surgery to address these and other complications.
Due to these disappointing and often life-altering results and increasing pressure from parents, Ponseti's noninvasive method gained momentum at the turn of the millennium. Since then, hundreds of comparative studies have shown its superiority to surgery with regard to primary correction rate, functional outcome and recurrence rate in both idiopathic and nonidiopathic clubfoot. If correctly done, the Ponseti method is successful in greater than 85 percent of cases.
The Ponseti method
Clubfoot treatment should begin in the first weeks of life to have the best chance for a successful outcome. Typical clubfoot cases usually require weekly manipulation and casting of the foot for six weeks; complex or syndromic cases may require more treatment. About 80 percent of infants require an Achilles tenotomy toward the end of casting. To maintain the correction, children generally wear a foot abduction brace 23 hours a day for three months, followed by part-time bracing at night and naptime until age 3.
"There is no doubt that the method is long, arduous and very involved," says Todd A. Milbrandt, M.D., a pediatric orthopedic surgeon at Mayo Clinic's campus in Rochester, Minnesota, who studied with Dr. Ponseti. "Nevertheless, most people now feel it is worth it to get better results."
Recurrences also are an issue. "With this treatment you do get recurrences," Dr. Milbrandt says. "The biggest reason is that parents become tired of the routine, so children stop wearing the brace as often as needed and the clubfoot comes back. If that occurs, the next step is to recast to correct the deformity, perform the Achilles tenotomy again, and then put the child back into shoes."
About 30 to 40 percent of children successfully treated with the Ponseti method will need a tibialis anterior tendon transfer to correct residual muscle imbalance from a strong tibialis anterior muscle and weak antagonists. It's unclear why the tibialis anterior muscle maintains relatively normal function and strength in clubfoot deformities, but the imbalance produces dynamic supination when a child walks.
One method of correction is the anterior tibialis tendon transfer, which involves transferring the entire tendon to the third cuneiform. The child then wears a non-weight-bearing cast for approximately six weeks. Improved muscle balance is usually apparent as soon as the cast is removed, and recurrences are very rare, Dr. Milbrandt says.
He also notes that a new tool in diagnosing early recurrence or dynamic supination is the pedobarograph, which documents in real time the pressure the bottom of the foot creates during the gait cycle. If increased lateral weight bearing is present, then the child may have an early recurrence.
"If left alone, children with a tibialis muscle imbalance will tend to walk on the outside of their feet, which can lead to stress fractures. We like to try to catch and treat it in the early phase," he explains.
On the horizon
Dr. Milbrandt thinks the future of clubfoot treatment may lie in genetic research like that currently being conducted at Washington University in St. Louis. Other advances may involve modifications of the Ponseti method that would make it less proscriptive and taxing.
"Some trials are looking at less bracing time or different braces — various ways to circumvent the very difficult proscriptive nature of the treatment," he says. "In five or 10 years, there may be changes in the time spent in a brace, but I don't foresee any changes in casting."
One other advance is the use of a brace with a pressure sensor in the heel that monitors the number of hours of daily wear.
"The sensor clicks on when the heel is in the brace and clicks off when the heel isn't," Dr. Milbrandt explains. "It can store up to 60 days' worth of data, and since we usually see patients once a month, we can download the data each visit.
"In our initial study of the device, we saw that bracing compliance was less than half of what we were told. Often, compliance dropped off 50 to 60 percent after the first month, and by the third month, it was even less.
"The problem is that the treatment is much more difficult for the family than for the child. We need to impress on parents that the procedure will lead to balanced, functional, pain-free feet, with no joint stiffness and that wearing the brace has a direct influence on clubfoot recurrence. The ankle joint and heel will move the way they should. Clubfoot kids can run and play soccer, and you would never know they had clubfeet."