Clubfoot

Clubfoot is a birth defect where one or both feet are rotated inward and downward. Congenital clubfoot is the most common congenital malformation of the foot with an incidence of 1 per 1000 births. In approximately 50% of cases, clubfoot affects both feet, but it can present unilaterally causing one leg or foot to be shorter than the other. Most of the time, it is not associated with other problems. Without appropriate treatment, the foot deformity will persist and lead to pain and impaired ability to walk, which can have a dramatic impact on the quality of life.

The exact cause is usually not identified. Both genetic and environmental factors are believed to be involved. There are two main types of congenital clubfoot: idiopathic (80% of cases) and secondary clubfoot (20% of cases). The idiopathic congenital clubfoot is a multifactorial condition that includes environmental, vascular, positional, and genetic factors. There appears to be hereditary component for this birth defect given that the risk of developing congenital clubfoot is 25% when a first-degree relative is affected. In addition, if one identical twin is affected, there is a 33% chance the other one will be as well. The underlying mechanism involves disruption of the muscles or connective tissue of the lower leg, leading to joint contracture. Other abnormalities are associated 20% of the time, with the most common being distal arthrogryposis and myelomeningocele. The diagnosis may be made at birth by physical examination or before birth during an ultrasound exam.

The most common initial treatment is the Ponseti method, which is divided into two phases: 1) correcting of foot position and 2) casting at repeated weekly intervals. If the clubfoot deformity does not improve by the end of the casting phase, an Achilles tendon tenotomy can be performed. The procedure consists of a small posterior skin incision through which the tendon cut is made. In order to maintain the correct position of the foot, it is necessary to wear an orthopedic brace until 5 years of age.

Initially, the brace is worn nearly continuously and then just at night. In about 20% of cases, further surgery is required. Treatment can be carried out by a range of healthcare providers and can generally be achieved in the developing world with few resources.

Clubfoot occurs in 1 to 4 of every 1,000 live births, making it one of the most common birth defects affecting the legs. About 80% of cases occur in developing countries where there is limited access to care. Clubfoot is more common in firstborn children and males. It is more common among Māori people, and less common among Chinese people.

Epidemiology

Birth prevalence of clubfoot varies between 0.51 and 2.03/1,000 live births in Low to middle income countries. It is one of the most common birth defects affecting the legs. Clubfoot is more common in firstborn children and males, who are twice as likely to be affected as females. It is more common among Māori people, and less common among Chinese people.

Clubfoot disproportionally affects those in low and middle-income countries (LMICs). About 80% of those with clubfoot, or approximately 100,000 children per year as of 2018, are born in LMICs.

History

Pharaohs Siptah and Tutankhamun had clubfeet, and the condition appears in Egyptian paintings. Indian texts () and Hippocrates () describe treatment. In 1823, Delpech presented a new procedure to treat the condition. The new method, known as tenotomy, involved the cutting of the Achilles tendon. The surgical procedure had complications such as infections.

Signs and symptoms

In clubfoot, feet are rotated inward and downward. The affected foot and leg may be smaller than the other, while in about half of cases, clubfoot affects both feet. Most of the time clubfoot is not associated with other problems.

Clubfoot can be diagnosed by ultrasound of the fetus in more than 60% of cases. The earliest week of gestation in which the condition is diagnosed with a high degree of confidence was the 12th and the latest was the 32nd. Not all patients were diagnosed at an early stage. In 29% of fetuses the first ultrasound examination failed to detect the deformity which subsequently became obvious at a later examination. Clubfoot was diagnosed between 12 and 23 weeks of gestation in 86% of children and between 24 and 32 weeks of gestation in the remaining 14%.

Without treatment the foot remains deformed and people walk on the sides or tops of their feet, which can cause calluses, foot infections, trouble fitting into shoes, pain, difficulty walking, and disability.

Causes

Hypotheses about the precise cause of clubfoot vary. However, research has found that genetics, environmental factors or a combination of both are associated with this condition. Evidence suggests that the etiology of clubfoot is most likely multifactorial. A meta-analysis and systematic review found that the most clinically relevant risk factors for clubfoot were family history, paternal and maternal smoking, maternal obesity, gestational diabetes, amniocentesis, and the use of selective serotonin re-uptake inhibitors (SSRIs). Many findings agree that "it is likely there is more than one different cause and at least in some cases the phenotype may occur as a result of a threshold effect of different factors acting together." The most commonly associated conditions are distal arthrogryposis or myelomeningocele. The factors contributing to the development of clubfoot can be categorized as extrinsic and intrinsic factors.

Extrinsic Factors

Factors that can influence the positioning of the fetal foot in uteru include oligohydramnios, breech presentation, Müllerian anomalies, multiple gestation, amniotic band sequence, or amniocentesis at <15 weeks of gestation. In cases that impede normal growth and position for longstanding period of times, clubfoot can be accompanied with other deformations and may be associated with developmental hip dysplasia. The theory of fetal growth arrest was proposed by Von Volkmann in 1863, and has been verified by other authors since. According to this theory, intrinsic errors or environmental insults during gestation prevents the correction of an equinovarus to pronated foot. Other researchers hypothesize that clubfoot may derive from external insults during gestation. For example, a research study found an alarming high incidence of club foot and limb contractures associated with iatrogenic amniotic leakage caused by early amniocentesis between the 11th and 12th week of gestation.

Intrinsic Factors

* ''Chromosomal abnormalities'' found in 30% and 2% of complex clubfoot and isolated clubfoot respectively. These include trisomy 18, 13, 21, sex chromosome abnormalities, micro-deletions and duplications.
* ''Genetic Syndromes:'' Larsen, Gordon, Pierre-Robin, Meckel-Gruber, Roberts, Smith-Lemli-Opitz, TARP (Talipes equinovarus, Atrial septal defect, Robin sequence, Persistence of left superior vena cava).
* ''Skeletal Dysplasias:'' Ellis van Creveld syndrome, diastrophic dysplasia, chondrodysplasia punctata, camptomelic dysplasia, atelosteogenesis, and mesomelic dysplasia.
* ''Neuromuscular and Neurologic abnormalities:'' arthrogryposis multiplex congenita, myotonic dystrophy, spinal muscular atrophy, neural tube defects, holoprosencephaly, and hydranencephaly.

Genetics

Clubfoot can be diagnosed prenatally as early as 13 weeks of gestation via ultrasound. According to the Society of Maternal-Fetal Medicine, a diagnostic testing for genetic causes is recommended when clubfoot is diagnoses prenatally. If prenatal screening is suspicious for aneuploidy, karyotype analysis or chromosomal microarray (CMA) may be performed. However, if patients decline diagnostic testing, Cell-Free DNA is another screening option to identify high-risk pregnancies for aneuploidy and it is not diagnostic. The incidence of chromosomal abnormalities in fetuses with prenatal diagnosis of clubfoot is relatively low. Overall, fetal ultrasound should be performed with a prenatal diagnosis of clubfoot in order to classify the condition as either complex or isolated because of the significant differences in rates of chromosomal abnormalities and outcomes between these two groups.

If one identical twin is affected, there is a 33% chance the other one will be as well.

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. Clubfoot can also be present in people with genetic conditions such as Loeys–Dietz syndrome and Ehlers-Danlos 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.

Diagnosis

Clubfoot is diagnosed through physical examination. Typically, babies are examined from head-to-toe shortly after they are born. There are four components of the clubfoot deformity:

Factors used to assess severity include the stiffness of the deformity (how much it can be corrected by manually manipulating the foot), the presence of skin creases at the arch and heel, and poor muscle consistency.

Sometimes, it is possible to detect clubfoot before birth using ultrasound. Prenatal diagnosis by ultrasound can allow parents to learn more about this condition and plan ahead for treatment after their baby is born.AskMayoExpert & et al. Can clubfoot be diagnosed in utero? Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2012.

More testing and imaging is typically not needed, unless there is concern for other associated conditions.

Treatment

Treatment is usually with some combination of the Ponseti method and French method. The Ponseti method involves a combination of casting, Achilles tendon release, and bracing. It is widely used and highly effective under the age of two. The French method involves realignment, taping, and long-term home exercises and night splinting. It is also effective but outcomes vary and rely on heavy involvement of caregivers. Generally, the Ponseti method is preferred. Another technique, the Kite method, does not appear to be as effective. In about 20% of cases, additional surgery is required after initial treatment.

Ponseti method

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 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 navicular 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. The foot must have the ability to dorsiflex to at least 10 degrees past 0 (neutral, or L position), although 15 degrees or more is better and preferred. If the foot can not dorsiflex enough, the brace will not work/be tolerated. If it is determined the foot can not dorsiflex at least 10 degrees, the Achilles Tenotomy surgical procedure is performed.
* ''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 (commonly 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 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 that is bent under the shoes at 10-15 degrees, or curved to create 10-15 degrees dorsiflexion. This device is also called a foot abduction brace (FAB) or more generally boots and bar (BnB). 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 3 months of 23/7 wear, the brace is worn less frequently by gradually reducing hours a couple at a time, every couple months so that hours are down to 12-14 per day at or around a year old. From this point on until at least 4–5 years, or even longer (6–9 years if needed), the brace is worn mostly while sleeping at night and during naps (12–14 hours per day). Bracing is essential in preventing recurrence of the deformity and is a major determinant of a child's long-term outcome.

The Ponseti method is highly effective with short-term success rates of 90%. However, anywhere from 14% to 41% of children experience a recurrence of the deformity. 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 seven times higher recurrence rates than those who follow bracing protocol, as the muscles around the foot can pull it back into the abnormal position. Low parental education level and failure to understand the importance of bracing is a major contributor to non-adherence. Relapses are managed by repeating the casting process. Relapsed feet may also require additional, more extensive surgeries and have a reduced chance of achieving subsequent correction.

Another reason for recurrence is a congenital muscle imbalance between the muscles that invert the ankle (tibialis posterior and tibialis anterior muscles) and the muscles that evert

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