Pes cavus, also called high arch, high foot arch, or high instep, refers to an abnormally high arch and shortening in the foot. The high arch might be inflexible and not flatten when an individual bears weight on the foot. Pes cavus is often observed in individuals with Charcot Marie Tooth (CMT) and Friedrich’s Ataxia (FA).

Pes cavus is common in individuals with Charcot Marie Tooth. In fact, this type of foot abnormity, along with lower leg weakness, may lead a physician to consider CMT as a diagnosis. Pes cavus occurs in CMT because the muscles in the feet weaken at different rates. While some of the muscles weaken, stronger muscles have more strength, and pull on the joints in the feet, causing the bones to move. This process can also be referred to as developing contractures. In CMT, the muscles that keep the foot lifted at the ankle often weaken, while the toes that lower the foot and curl the foot downward remain strong. This causes the development of a shortened foot with a high arch. Over time, the contracture may worsen, causing the toes to lock into a flexed position. The abnormal weight distribution of the foot causes to unusual friction, leading to calluses, blistering, and abrasions. As contractures worsen, walking may become more difficult.

Physical therapy has been found to be effective in decreasing contractures of the foot for individuals with CMT. An individualized program of low-impact exercise and stretching exercises may be prescribed. The development of contractures may be delayed through the use of Ankle Foot Orthosis (AFOs). AFOs enable the individual to walk in a more normal position. AFOs also decrease stress on the ankles. In the case of severe contractures, surgery to loosen tight tendons and muscles might be performed.

About half of those diagnosed with Friedrich’s Ataxia (FA) have pes cavus. The foot will be shortened and the arch will be abnormally high. In those with FA who are able to walk, this causes painful difficulties with blisters and calluses. In many individuals with Friedrich’s Ataxia, pes cavus occurs at an early age. While pes cavus is often caused by contractures, in Friedrich’s Ataxia, there has been speculation that the deficiency of frataxin may directly affect bone development.

For individuals with Friedrich’s Ataxia, physical therapy may be prescribed to increase flexibility through stretching muscles. Surgery might be performed to correct foot deformities, as well.

Other types of neuromuscular disease, including muscular dystrophy and myopathy, can also cause pes cavus. The pes cavus seen in individuals with neuromuscular disease is caused by muscle imbalance.


Resources:
MDA, (20011). Facts About Charcot Marie Tooth and Related Diseases. Available as a downloadable .pdf file at http://www.mda.org/publications/ . Retrieved on June 14, 2012.

MDA, (2011). Facts about Friedrich’s Ataxia. Available as a downloadable .pdf file at http://www.mda.org/publications/ . Retrieved on June 14, 2012.

Medline Plus, (2012). High Arch. Medline Plus website. http://www.nlm.nih.gov/medlineplus/ency/article/001261.htm . Retrieved June 14, 2012.

Turner, N.S., et al., (2010). Pes Cavus. Medscape Reference website. http://emedicine.medscape.com/article/1236538-overview . Retrieved on June 14, 2012.

Wahl, M., (2006). Surgery Sometimes, Bracing Often, Caution Always: Caring for the CMT-Affected Foot. QUEST, 13:5. http://www.mda.org/publications/Quest/q135cmt_foot.html . Retrieved on June 14, 2012.