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.[9]

Among the cases of neuromuscular pes cavus, 50% have been attributed to Charcot-Marie-Tooth disease, CMT,[10] which is the most common type of inherited neuropathy with an incidence of 1 per 2,500 persons affected.[11] Also known as Hereditary Motor and Sensory Neuropathy (HMSN), it is genetically heterogeneous and occasionally idiopathic. (See CMT Association website) There are many different types and subtypes of CMT, and as a result, it can present from infancy through to adulthood. CMT is a peripheral neuropathy, affecting the distal muscles first as weakness, clumsiness, and frequent falls. It usually affects the feet first, but can sometimes begin in the hands. Charcot-Marie-Tooth disease can cause painful foot deformities such as pes cavus. Although it is a relatively common disease, many doctors and laypersons are not familiar with it. There are no cures or effective courses of treatment to halt the progression of any form of Charcot-Marie-Tooth disease at this time.[12]

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.[9]

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.[13]

On weightbearing projectional radiography, pes cavus can be diagnosed and graded by several features, the most important being medial peritalar subluxation, increased calcaneal pitch (variable) and abnormal talar-1st metatarsal angle (Meary's angle).[14] Medial peritalar subluxation can be demonstrated by a medially rotated talonavicular coverage angle.[14]

• 
  Dorsoplantar projectional radiograph of the foot showing the measurement of the talonavicular coverage angle.
• 
  Weight-bearing lateral X-ray showing the measurement of calcaneal pitch, which is an angle of the calcaneus and the inferior aspect of the foot, with different sources giving different reference points.[15] Calcaneal pitch is increased in pes cavus, with cutoffs ranging from 20° to 32°.[14]
• 
  Same lateral X-ray showing the measurement of Meary's angle, which is the angle between the long axis of the talus and first metatarsal bone.[14] This example is slightly convex downward. An angle greater than 4° convex upward is considered pes cavus.[14]
• 
  Foot with pes cavus (and os peroneum).

Surgical treatment is only initiated if there is severe pain, as the available operations can be difficult. Otherwise, high arches may be handled with care and proper treatment.

Suggested conservative management of patients with painful pes cavus typically involves strategies to reduce and redistribute plantar pressure loading with the use of foot orthoses and specialised cushioned footwear.[20][21] Other non-surgical rehabilitation approaches include stretching and strengthening of tight and weak muscles, debridement of plantar callosities, osseous mobilization, massage, chiropractic manipulation of the foot and ankle, and strategies to improve balance.[22] There are also numerous surgical approaches described in the literature that are aimed at correcting the deformity and rebalancing the foot. Surgical procedures fall into three main groups:

1. soft-tissue procedures (e.g. plantar fascia release, Achilles tendon lengthening, tendon transfer);
2. osteotomy (e.g. metatarsal, midfoot or calcaneal);
3. bone-stabilising procedures (e.g. triple arthrodesis).[23]

There are few good estimates of prevalence for pes cavus in the general community. While pes cavus has been reported in between 2 and 29% of the adult population, there are several limitations of the prevalence data reported in these studies.[1] Population-based studies suggest the prevalence of the cavus foot is approximately 10%.[24]

The term pes cavus is Latin for "hollow foot" and is synonymous with the terms talipes cavus, cavoid foot, high-arched foot, and supinated foot type. Pes cavus is a multiplanar foot deformity characterised by an abnormally high medial longitudinal arch. Pes cavus commonly features a varus (inverted) hindfoot, a plantarflexed position of the first metatarsal, an adducted forefoot, and dorsal contracture of the toes. Despite numerous anecdotal reports and hypothetical descriptions, very little rigorous scientific data exist on the assessment or treatment of pes cavus.[25]

• Arches of the foot
• Foot type
• En pointe
• Foot binding
• Rocker bottom foot