Clubfoot 

Clubfoot can be classified as (1) postural or positional or (2) fixed or rigid. Postural or positional clubfeet are not true clubfeet. Fixed or rigid clubfeet are either flexible (ie, correctable without surgery) or resistant (ie, require surgical release, though this is not entirely true according to the Ponseti experience^{[1, 2, 3]} ).

See images related to clubfoot below:

The Pirani, Goldner, Di Miglio, Hospital for Joint Diseases (HJD), and Walker classifications have been published, but no classification system is universally used.^{[4, 5, 6]}

Recent studies

Parker et al pooled data from several birth defects surveillance programs (6139 cases of clubfoot) to better estimate the prevalence of clubfoot and investigate its risk factors. The overall prevalence of clubfoot was 1.29 per 1,000 livebirths, with 1.38 among non-Hispanic whites, 1.30 among Hispanics, and 1.14 among non-Hispanic blacks or African Americans. Maternal age, parity, education, and marital status were significantly associated with clubfoot, along with maternal smoking and diabetes.^[7]

Steinman et al compared the Ponseti and French functional method for idiopathic clubfeet (265 feet [176 patients] by Ponseti method; 119 feet [80 patients] by French functional method). The study showed that although there was a trend toward improved results with the Ponseti method, the difference was not significant. Parents chose the Ponseti method twice as often as the French functional method. Initial correction rates were 94.4% for the Ponseti method and 95% for the French functional method. Relapses occurred in 37% of the Ponseti-method feet, and in a third of these cases, further nonoperative treatment was successful; however, surgical treatment was necessary for the other two thirds. Relapses occurred in 29% of the feet treated by the French functional method; surgical intervention was necessary in all those cases. At the latest follow-up, outcomes with the Ponseti method were good in 72% of cases, fair in 12%, and poor in 16%. For the French functional method, outcomes were good in 67%, fair in17%,and poor in 16%.^[8]

Parada et al reviewed the safety of general anesthesia in infants who underwent percutaneous tendoachilles tenotomy. The procedure was performed in 137 patients (182 tenotomies). Of the tenotomies, 92 were unilateral and 45 bilateral. No complications related to anesthesia were identified, and nearly all patients were discharged on the day of surgery.^[9]

In the past, clubfoot surgery was performed in a way that did not differentiate severity. The same procedure was performed for all patients. Bensahel has proposed a more individualized approach (ie, addressing only the structures that are required are released). The surgery is tailored to the deformity. For example, if the forefoot is well corrected and externally rotated, if there is no cavus, but if there is still significant equinus, a posterior approach alone should suffice (see Intraoperative details).^[10]

See Relevant Anatomy.

Frequency

The incidence of clubfoot is approximately 1 case per 1000 live births in the United States. The incidence differs among ethnicities. For example, it is close to 75 cases per 1000 live births in the Polynesian islands, particularly in Tonga.

The male-to-female ratio is 2:1. Bilateral involvement is found in 30-50% of cases. There is a 10% chance of a subsequent child being affected if the parents already have a child with a clubfoot.

The true etiology of congenital clubfoot is unknown. Most infants who have clubfoot have no identifiable genetic, syndromal, or extrinsic cause.^[7]

Extrinsic associations include teratogenic agents (eg, sodium aminopterin), oligohydramnios, and congenital constriction rings. Genetic associations include mendelian inheritance (eg, diastrophic dwarfism; autosomal recessive pattern of clubfoot inheritance).

Cytogenetic abnormalities (eg, congenital talipes equinovarus [CTEV]) can be seen in syndromes involving chromosomal deletion. It has been proposed that idiopathic CTEV in otherwise healthy infants is the result of a multifactorial system of inheritance.^[11] Evidence for this is as follows:

• Incidence in the general population is 1 per 1000 live births.
• Incidence in first-degree relations is approximately 2%.
• Incidence in second-degree relations is approximately 0.6%.
• If one monozygotic twin has a CTEV, the second twin has only a 32% chance of having a CTEV.

Theories of the pathogenesis of clubfeet are as follows:

• Arrest of fetal development in the fibular stage
• Defective cartilaginous anlage of the talus
• Neurogenic factors: Histochemical abnormalities have been found in posteromedial and peroneal muscle groups of patients with clubfeet. This is postulated to be due to innervation changes in intrauterine life secondary to a neurologic event, such as a stroke leading to mild hemiparesis or paraparesis. This is further supported by a 35% incidence of varus and equinovarus deformity in spina bifida.
• Retracting fibrosis (or myofibrosis) secondary to increased fibrous tissue in muscles and ligaments: In fetal and cadaveric studies, Ponseti also found the collagen in all of the ligamentous and tendinous structures (except the Achilles tendon), and it was very loosely crimped and could be stretched. The Achilles tendon, on the other hand, was made up of tightly crimped collagen and was resistant to stretching. Zimny et al found myoblasts in medial fascia on electron microscopy and postulated that they cause medial contracture.^{[1, 2, 12]}
• Anomalous tendon insertions: Inclan proposed that anomalous tendon insertions result in clubfeet.^[13] However, other studies have not supported this. It is more likely that the distorted clubfoot anatomy can make it appear that tendon insertions are anomalous.
• Seasonal variations: Robertson noted seasonal variations to be a factor in his epidemiologic studies in developing countries.^[14] This coincided with a similar variation in the incidence of poliomyelitis in the children in the community. Clubfoot was therefore proposed to be a sequela of a prenatal poliolike condition. This theory is further supported by motor neuron changes in the anterior horn in the spinal cord of these babies.

Seek a detailed family history of clubfoot or neuromuscular disorders, and perform a general examination to identify any other abnormalities. Examine the feet with the child prone, with the plantar aspect of the feet visualized, and supine to evaluate internal rotation and varus. If the child can stand, determine if the foot is plantigrade, if the heel is bearing weight, and if it is in varus, valgus, or neutral.

Similar deformities are seen with myelomeningocele and arthrogryposis. Therefore, always examine for these associated conditions. The ankle is in equinus, and the foot is supinated (varus) and adducted (a normal infant foot usually can be dorsiflexed and everted, so that the foot touches the anterior tibia). Dorsiflexion beyond 90° is not possible.

The navicular is displaced medially, as is the cuboid. Contractures of the medial plantar soft tissues are present. Not only is the calcaneus in a position of equinus but also the anterior aspect is rotated medially and the posterior aspect laterally.

The heel is small and empty. The heel feels soft to the touch (akin to the feel of the cheeks). As the treatment progresses, it fills in and develops a firmer feel (akin to the feel of the nose or of the chin).

The talar neck is easily palpable in the sinus tarsi as it is uncovered laterally. Normally, this is covered by the navicular, and the talar body is in the mortise. The medial malleolus is difficult to palpate and is often in contact with the navicular. The normal navicular-malleolar interval is diminished.

The hindfoot, as shown below, is supinated, but the foot is often in a position of pronation relative to the hindfoot. The first ray often drops to create a position of cavus. The Ponseti method of closed management of clubfeet through manipulations and casting describes the elevation of the first metatarsal as a first step, even if it means seemingly exacerbating the supination of the foot.

The tibia often has internal torsion. This assumes special importance in the casting management of clubfeet, as shown in the images below, where care should be taken to rotate the feet into abduction, avoiding spurious tibial rotation through the knee.

Even following correction, the foot often remains short and the calf thin.

Traditionally, surgery is indicated when a plateau has been reached in nonoperative treatment. Surgery is usually performed when the child is of sufficient size to enable anatomy to be recognized.

• Bone

  • Tibia: Slight shortening is possible.
  • Fibula: Shortening is common.
  • Talus: In equinus in the ankle mortise, with the body of the talus being in external rotation, the body of the talus is extruded anterolaterally and is uncovered and can be palpated. The neck of the talus is medially deviated and plantar flexed. All relationships of the talus to the surrounding bones are abnormal.
  • Os calcis: Medial rotation and an equinus and adduction deformity are present.
  • Navicular: The navicular is medially subluxated over the talar head.
  • Cuboid: The cuboid is medially subluxated over the calcaneal head.
  • Forefoot: The forefoot is adducted and supinated; severe cases also have cavus with a dropped first metatarsal.
• Muscle

  • Atrophy of the leg muscles, especially in the peroneal group, is seen in clubfeet.
  • The number of fibers in the muscles is normal, but the fibers are smaller in size.
  • The triceps surae, tibialis posterior, flexor digitorum longus (FDL), and flexor hallucis longus (FHL) are contracted.
  • The calf is of a smaller size and remains so throughout life, even following successful long-lasting correction of the feet.
• Tendon sheaths: Thickening frequently is present, especially of the tibialis posterior and peroneal sheaths.
• Joint capsules: Contractures of the posterior ankle capsule, subtalar capsule, and talonavicular and calcaneocuboid joint capsules commonly are seen.
• Ligaments: Contractures are seen in the calcaneofibular, talofibular, (ankle) deltoid, long and short plantar, spring, and bifurcate ligaments.
• Fascia: The plantar fascial contracture contributes to the cavus, as does contracture of fascial planes in the foot.

No specific contraindications to surgery exist, although the child's size dictates that surgery is best performed at approximately age 6 months. With greater acceptance of the Ponseti conservative technique, surgery is seen to be a contentious issue. Surgery for clubfeet is no longer the only standard of care.