Clubfoot

Clubfoot is a congenital or acquired 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 and secondary clubfoot. 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.
Congenital 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 and middle-income countries.
Clubfoot disproportionally affects those in 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.
Lord Byron was club-footed of his right foot. Some modern medical authors maintain that it was a consequence of infantile paralysis, and others that it was a dysplasia, a failure of the bones to form properly.
Talleyrand might have had a congenital clubfoot, which if his uncle did as well, could have been genetic. In any case, his handicap made him unable to follow his father into a military career, leaving the obvious career of the Church.

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. 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 utero 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 alarmingly 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.
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 diagnosed prenatally. If prenatal screening is suspicious for aneuploidy, karyotype analysis or chromosomal microarray 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. These can cause congenital contractures, including clubfoot, in distal arthrogryposis 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:

1		Cavus: the foot has a high arch, or a caved appearance.
2		Adductus: the forefoot curves inwards toward the big toe.
3		Varus: the heel is inverted, or turned in, forcing one to walk on the outside of the foot. This is a natural motion but in clubfoot the foot is fixed in this position.
4		Equinus: the foot is pointed downward, forcing one to walk on tiptoe. This motion occurs naturally, but in clubfoot the foot is fixed in this position. This is because the Achilles tendon is tight and pulls the foot downwards.

Factors used to assess severity include the stiffness of the deformity, 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.
More testing and imaging is typically not needed, unless there is concern for other associated conditions.