Synonym
medical: Pes equinovarus
Innate form
This form belongs to the extremity deformities, but it is a combination of different deformities of the foot. Furthermore, the sole of the foot shows an inward rotation inwards (supination) and the lower leg muscles show anomalies. The congenital form of clubfoot occurs with a frequency of 1:1000, with boys being affected about twice as often as girls.
This makes clubfoot the second most common congenital malformation after hip joint malposition (hip dysplasia). The cause of this congenital malformation is not yet completely clear. It is suspected that the muscles and connective tissue are not formed in the correct proportion.
This results in a muscle imbalance, which alters bone growth and could lead to the development of clubfoot. Another explanation is that the development of the foot stops at an earlier stage and therefore resembles an early embryonic foot. There are several hypotheses for these abnormal developments, such as an unfavorable position of the embryo, a reduction in the amount of amniotic fluid, and the consequence of taking drugs such as folic acid antagonists (methotrexate). This foot malposition can occur on one or both sides, but in half of the cases both feet are affected by the malposition.
Appearance
The congenital limb malposition is a combination of several deformities. It is a complex and severe malformation of the entire foot and not only a malposition of the joints. In the case of a clubfoot, an inward twisting (supination) of the foot occurs with the sole of the foot pointing inwards: Pes varus.
In addition, the foot is in a pointed foot position, whereby the foot is pulled towards the sole of the foot in the upper ankle joint: Pes equinus. This explains the synonym “Pes equniovarus”. As a rule, further malpositioning of the feet can be found: sickle-foot position of the forefoot (Pes adductus) and a hollow foot (Pes excavatus). This is associated with a shortening of the Achilles tendon. As a result, patients can walk on the outer edge of the foot without treatment, and in particularly severe cases only on the back of the foot.