Ignacio V. Ponseti can be credited with developing a comprehensive technique for treating congenital clubfoot in the 1940s. One of the major principles of this technique is the concept that the tissues of a newborn's foot, including tendons, ligaments, joint capsules, and certain bones, will yield to gentle manipulation and casting of the feet at weekly intervals. By applying this technique to clubfeet within the first few weeks of life, most clubfeet can be successfully corrected without the need for major reconstructive surgery.
This technique is based upon Ponseti's experiences with the wide variety of treatments being applied at that time and his observations in the clinic and operating room, as well as his anatomic dissections and analysis by using a movie camera to produce radiographic images. Utilizing these principles and his understanding of clubfoot anatomy, Dr. Ponseti began employing this technique in 1948 at the University of Iowa. Recently, his observations have been confirmed using modern techniques, including Magnetic Resonance Imaging (MRI).
The Ponseti technique has become the most widely practiced method for initial treatment of infants born with clubfeet. It is an easy technique to learn and, when applied accurately, it yields excellent results.
The corrective process utilizing the Ponseti technique can be divided into two phases:
During each of these phases, attention to the details of the technique is essential to minimize the possibility of incomplete correction and recurrences.
The treatment phase should begin as early as possible, optimally within the first week of life. Gentle manipulation and casting is performed on a weekly basis. Each cast holds the foot in the corrected position, allowing it to gradually re-shape. Generally, five to six casts are required to fully correct the alignment of the foot and ankle. At the time of the final cast, the majority of infants (70% or higher) will require a percutaneous surgical procedure (with a small incision through the skin) to gain adequate lengthening of their Achilles tendon.
The final cast remains in place for three weeks, after which the infant's foot is placed into a removable orthotic device. The orthosis is worn 23 hours per day for three months and then during the night-time for several years. Failure to use the orthosis correctly may result in recurrence of the clubfoot deformity. Good results have been demonstrated at multiple centers, and long-term results indicate that foot function is comparable with that of normal feet.
The unique manipulation and casting maneuvers used in the Ponseti technique are just two examples of several elements which make it quite distinct from other casting methods.
First Cast: Prior to casting, the position of the forefoot (front of the foot) in relation to the heel creates cavus (abnormally high arch) of the foot. The first cast application addresses the foot deformity, aligning the forefoot with the hindfoot (back of the foot). In doing so, the cavus (Figure 1) is corrected (Figure 2), typically after one cast. (Figure 3)
Figure 1: Before treatment. The marked curvature of the foot, called a cavus deformity, is characterized by a visible crease in the midsection of the foot. The foot is tilted down due to tightness of the Achilles tendon.
Figure 2: The initial Ponseti cast. Note the positioning of the forefoot to align with the heel, with the outer edge of the foot tilted even further downward due to Achilles tendon tightness.
Figure 3: After the first cast, the foot is straight and the cavus and crease are no longer evident.
It is usually easiest to apply the cast in two stages: first a short-leg cast to just below the knee, which is then extended above the knee once the plaster sets. This is preferable in older children (beyond 2 to 3 months) who are stronger and less easily consoled during the casting. Ponseti emphasizes the importance of long-leg casts, which are essential to maintain adequate stretching of tendons and ligaments.
Second Cast: One week later, the first cast is removed and, after a short period of manipulation, the next toe-to-groin plaster cast is applied.(Figure 4)
Figure 4: The second cast is applied with the outer edge of the foot still tilted downward and the forefoot moved slightly outward.
This phase in the manipulation and casting process is focused on straightening the foot, aligning the forefoot with the heel. Care is taken to maintain the downward tilt of the foot; correction of this downward tilt - due to tightness of the ankle - will occur in subsequent casts. Before casting, the physician manipulates the forefoot according to Ponseti's carefully described technique in order to stretch the foot, determining the amount of correction that can be maintained when the plaster cast is applied.
Another crucial point in the Ponseti technique, which is radically different than other techniques, is that the heel is never directly manipulated. The gradual correction of the hindfoot and midfoot are such that the heel will naturally move into a correct position.
Further Casting: Manipulation and casting is continued on a weekly basis for the next two to three weeks in order to gradually straighten the forefoot, allowing the forefoot to move in line with the heel. (Figure 5)
Figure 5: The third cast. The Achilles tendon is stretched, bringing the outer edge of the foot into a more normal position as the forefoot is turned further outward.
After four or five casts have been applied, normal position of the foot will begin to be observed.
The Achilles tendon: The Achilles tendon is the cord behind the ankle that allows the ankle to move up and down. In children with clubfoot this tendon is shortened, preventing the ankle from bending up properly. In the majority of these children the tendon must be lengthened in order to allow sufficient ankle motion. In the Ponseti technique, this is accomplished with a percutaneous surgical release of the tendon, which allows the ankle to be positioned at a right angle with the leg. This percutaneous release is a quick procedure that is typically done through a small puncture, under local anesthesia.
The final cast: The foot and ankle are then casted in the final, corrected position. (Figure 6)
Figure 6: The final cast is applied, and the Achilles tendon is stretched further with the forefeet pointed upward. This cast is typically applied in 2 stages, with the short leg component extended up to the groin once the lower component has hardened.
A total of five or six casts are typically needed to correct the foot and ankle. More are rarely needed in the most severe cases of clubfoot.
Upon removal of the final cast, the infant is placed into an orthosis, or brace, which maintains the foot in its corrected position. The purpose of this splinting, after the casting phase in the Ponseti method, is to maintain the foot in the proper position, with the forefeet set apart and pointed upward. This is accomplished with a brace consisting of shoes mounted to a bar. (Figure 7)
Figure 7: Image of the foot orthotic.
The brace is worn 23 hours per day for the first three months following casting and then while sleeping for several years to follow, usually until around age three or four. Two recent studies have demonstrated the high risk for recurrence if the brace is not worn according to these guidelines. The reasons for recurrence in feet that appear to be fully corrected have not yet been clearly proven, but regardless of the cause, recurrence appears to be close to zero when the bracing regimen is followed accurately.
In one study, researchers reported no recurrences among patients compliant with the foot abduction orthosis compared with 57% recurrence among non-compliant patients when studied at short-term follow-up. (Thacker MM, Scher DM, Sala DA, et al: Use of the foot abduction orthosis following Ponseti casts: Is it essential? J Pediatric Orthop 25:225-228, 2005)
Management of Recurrence
The risk of recurrence persists for several years after the casting is completed. Ponseti reported a recurrence rate of approximately 50% in his early series, but noted a decrease with greater emphasis placed on the use of the foot orthotic. Early recurrences are best treated with several long-leg plaster casts applied at two-week intervals. The first cast may require correction of recurrent foot deformity, with subsequent casts to correct ankle tightness.
An Achilles tendon lengthening may be necessary if there is insufficient correction at the ankle, and a tendon transfer (of the tibialis anterior tendon) may be performed in older children to help maintain the correction. Following this additional surgery, the child is then placed in a long-leg cast for four weeks with the foot in neutral position.
The Ponseti technique is gaining widespread acceptance as the treatment of choice for infants with clubfeet. It is now even implemented in several third-world countries, where it is supported by their national health systems and administered by casting specialists and technicians. If a child's physician meticulously follows the details of this technique and applies all of the elements without modification, parents can expect optimal results in the short and long term for children with clubfeet.
Summary by Mike Elvin