Cause of Pes Cavus
Pes cavus may be hereditary or acquired, and the underlying cause may be neurological, orthopedic or neuromuscular. Pes cavus is sometimes—but not always—connected through Hereditary Motor and Sensory Neuropathy Type 1 (Charcot-Marie-Tooth disease) and Friedreich's Ataxia; many other cases of pes cavus are natural.
The cause and deforming mechanism underlying pes cavus is complex and not well understood. Factors considered influential in the development of pes cavus include muscle weakness and imbalance in neuromuscular disease, residual effects of congenital clubfoot, post-traumatic bone malformation, contracture of the plantar fascia and shortening of the Achilles tendon.
Among the cases of neuromuscular pes cavus, 50% have been attributed to Charcot-Marie-Tooth disease which is the most common type of inherited neuropathy with an incidence of 1 per 2,500 persons affected. Also known as Hereditary Motor and Sensory Neuropathy (HMSN), it is genetically heterogeneous and usually presents in the first decade of life with delayed motor milestones, distal muscle weakness, clumsiness and frequent falls. By adulthood, Charcot-Marie-Tooth disease can cause painful foot deformities such as pes cavus. Although it is a relatively common disorder affecting the foot and ankle, surprisingly little is known about the distribution of muscle weakness, severity of orthopaedic deformities, or types of foot pain experienced. Currently, there are no cures or effective treatment to halt the progression of any form of Charcot-Marie-Tooth disease.
The development of the cavus foot structure seen in Charcot-Marie-Tooth disease has been previously linked to an imbalance of muscle strength around the foot and ankle. A hypothetical model proposed by various authors describes a relationship whereby weak evertor muscles are overpowered by stronger invertor muscles causing an adducted forefoot and inverted rearfoot. Similarly, weak dorsiflexors are overpowered by stronger plantarflexors causing a plantarflexed first metatarsal and anterior pes cavus.
Pes cavus is also evident in people without neuropathy or other neurological deficit. In the absence of neurological, congenital or traumatic causes of pes cavus, the remaining cases are classified as being ‘idiopathic’, because their aetiology is unknown.
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