Clubfoot

Mutations in genes involved in muscle development are risk factors for clubfoot, specifically those encoding the muscle contractile complex (MYH3, TPM2, TNNT3, TNNI2 and MYH8). These can cause congenital contractures, including clubfoot, in distal arthrogryposis (DA) syndromes.[8] Clubfoot can also be present in people with genetic conditions such as Loeys–Dietz syndrome.

Genetic mapping and the development of models of the disease have improved understanding of developmental processes. Its inheritance pattern is explained as a heterogenous disorder using a polygenic threshold model. The PITX1-TBX4 transcriptional pathway has become key to the study of clubfoot. PITX1 and TBX4 are uniquely expressed in the hind limb.[9]

A foot abduction brace type Denis Browne bar. Various types of foot-abduction braces are used to hold the child's feet in the desired position.

The Ponseti method corrects clubfoot over the course of several stages.

• Serial casting: First, the foot is manually manipulated into an improved position and held in place with a long leg plaster cast which extends from the toes up to the thigh. After a week this cast is removed, the foot is re-manipulated, and placed into a new cast. This process repeats and the foot is gradually reshaped over the course of 4-6 serial casts, although some feet may require additional casts.
  • The goal of the initial cast is to align the forefoot with the hindfoot. Ponseti describes the forefoot as pronated in relation to the hindfoot, so supinating the forefoot and elevating the first metatarsal improves this alignment.
  • Subsequent casts are applied after stretching the foot with a focus on abducting the forefoot with lateral pressure at the talus, to bring the navicula laterally and improve the alignment of the talonavicular joint. In contrast to the Kite method of casting, it is important to avoid constraining the calcanocuboid joint. With each additional cast, the abduction is increased and this moves the hindfoot from varus into valgus. It is important to leave the ankle in equinus until the forefoot and hindfoot are corrected.
  • The final stage of casting, is to correct the equinus. After fully abducting the forefoot with spontaneous correction of the hindfoot, an attempt is made to bring the ankle up and into dorsiflexion.
• Achilles tendon release: At the end of the serial casting, most children have corrected cavus, adductus and varus deformities, but continue to have equinus deformity. To correct this, a procedure called an Achilles tendon release (also called Achilles tenotomy) is performed. Before the procedure, many centers place the child under sedation or monitored anesthesia care, although Ponseti recommended using local anesthetic alone. Next, the area around the heel is cleansed and numbed, and a small scalpel is used to cut the Achilles tendon. The incision is small so there is minimal bleeding and no need for stitches. The skin is covered with a small dressing, and the foot is placed into a final long leg cast in a fully corrected position. This cast is typically left in place for three weeks. During this time, the Achilles tendon will regrow in a lengthened position.
• Bracing: After successful correction is achieved through serial casting and Achilles tenotomy, the foot must be kept in a brace to prevent it from returning back to the deformed position over the first few years of a child's life. The brace is made up of two shoes or boots that are connected to each other by a bar. This device is also called a foot abduction brace (FAB). At first, the brace is worn full-time (23 hours per day) on both feet, regardless of whether the clubfoot affects one or two feet. After several months, or once the child start pulling to stand, the brace is worn less frequently, mostly while sleeping at night and during naps. This part-time bracing phase continues until four years of age. Bracing prevents recurrence of the deformity and is a major determinant of a child's long-term outcome.[13]

The Ponseti Method is highly effective with short-term success rates of 90%.[13] However, anywhere from 14% to 41% of children experience a recurrence of the deformity.[14] The most common reason for this is inadequate adherence to bracing, such as not wearing the brace properly, not keeping it on for the recommended length of time, or not using it every day. Children who do not follow proper bracing protocol have up to 7 times higher recurrence rates than those who follow bracing protocol.[14]

A recurrence can usually be managed with repeating the casting process. Recurrence is more common when there is poor compliance with the bracing, because the muscles around the foot can pull it back into the abnormal position. Approximately 20% of infants successfully treated with the Ponseti casting method will have an imbalance between the muscles that invert the ankle (posterior tibialis and anterior tibialis muscles) and the muscles that evert the ankle (peroneal muscles). Patients with this imbalance are more prone to recurrence. After 18 months of age, this can be addressed with surgery to transfer the anterior tibialis tendon from its medial attachment (the navicula) to a more lateral position (the lateral cuneiform) to rebalance these muscle forces. While this requires a general anesthetic and subsequent casting while the tendon heals, it is a relatively minor surgery that corrects a persistent muscle imbalance while avoiding disturbance to the joints of the foot.

The French method for treatment of clubfoot is a conservative method of treatment of a newborn which requires daily physical therapy for the first two months. The goal of this treatment is to avoid future need of surgery, but the success rate varies and after release surgery may still be necessary. The treatment includes daily manipulations of the feet along with stretching of the feet, followed by taping in order to maintain the range of motion gains achieved at the end of each session.

The French method differs from the Ponseti method in that the taping techniques allow some motion in the feet. Another focus is to strengthen the peroneal muscles which is thought to contribute towards long-term correction. After the two month mark physical therapy sessions can be weaned down to three times per week instead of daily until the child reaches six months. Parents are required to continue on with home exercises and night splinting even after the program has achieved proper foot correction in order to maintain the correction. The Ponseti method is generally preferred.[3]

If non-operative treatments are unsuccessful or achieve incomplete correction of the deformity, surgery is sometimes needed. Surgery was more common prior to the widespread acceptance of the Ponseti Method. The extent of surgery depends on the severity of the deformity. Usually, surgery is done at 9 to 12 months of age and the goal is to correct all the components of the clubfoot deformity at the time of surgery.

For feet with the typical components of deformity (cavus, forefoot adductus, hindfoot varus, and ankle equinus), the typical procedure is a Posteromedial Release (PMR) surgery. This is done through an incision across the medial side of the foot and ankle, that extends posteriorly, and sometimes around to the lateral side of the foot. In this procedure, it is typically necessary to release (cut) or lengthen the plantar fascia, several tendons, and joint capsules/ligaments. Typically, the important structures are exposed and then sequentially released until the foot can be brought to an appropriate plantigrade position. Specifically, it is important to bring the ankle to neutral, the heel into neutral, the midfoot aligned with the hindfoot (navicula aligned with the talus, and the cuboid aligned with the calcaneus). Once these joints can be aligned, thin wires are usually placed across these joints to hold them in the corrected position. These wires are temporary and left out through the skin for removal after 3–4 weeks. Once the joints are aligned, tendons (typically the Achilles, posterior tibialis, and flexor halluces longus) are repaired at an appropriate length. The incision (or incisions) are closed with dissolvable sutures. The foot is then casted in the corrected position for 6–8 weeks. It is common to do a cast change with anesthesia after 3–4 weeks, so that pins can be removed and a mold can be made to fabricate a custom AFO brace. The new cast is left in place until the AFO is available. When the cast is removed, the AFO is worn to prevent the foot from returning to the old position.[10]

For feet with partial correction of deformity with non-operative treatment, surgery may be less extensive and may involve only the posterior part of the foot and ankle. This might be called a posterior release. This is done through a smaller incision and may involve releasing only the posterior capsule of the ankle and subtalar joints, along with lengthening the Achilles tendon.

Surgery leaves residual scar tissue and typically there is more stiffness and weakness than with nonsurgical treatment. As the foot grows, there is potential for asymmetric growth that can result in recurrence of foot deformity that can affect the forefoot, midfoot, or hindfoot. Many patients do fine, but some require orthotics or additional surgeries. Long-term studies of adults with post-surgical clubfeet, especially those needing multiple surgeries, show that they may not fare as well in the long term.[15] Some people may require additional surgeries as they age, though there is some dispute as to the effectiveness of such surgeries, in light of the prevalence of scar tissue present from earlier surgeries.

Those in LMICs are disproportionally affected. Though the Ponseti method has proven to be an effective, many children in LMICs face barriers including lack of access to resources – specifically casting materials and abduction braces. Other barriers include shortage of healthcare professionals, financial constraints of the existing institutions, training and education level of healthcare professionals and families failing to follow-up with appointments.[16] Well access has increased, coverage is not comprehensive with an estimated 15% of those diagnosed with clubfoot receiving treatment.[17] Recommendations include giving providers more knowledge of how to improve accessibility. Considerations include: early diagnosis, organizing high-volume Ponseti casting centers, using non-physician health workers, engaging families in care, addressing barriers to access, and providing follow-up in the person’s community.[18]