The adult cavus foot

Pes cavus is an increase of normal plantar concavity, where the anterior and posterior weight-bearing areas of the foot are brought closer together. A wide spectrum of foot deformities includes a plantarflexed first ray, forefoot pronation and adduction, and hindfoot varus or high calcaneal pitch.1,2 Cavovarus deformity can be classified according to the severity of malalignment ranging from a subtle and flexible cavovarus foot to a severe and fixed cavovarus deformity. There are many aetiologies of unequal frequency that account for cavovarus foot deformities. Traumatic causes are rare (improperly treated fracture or subluxation of the tarsal bones or scarring from a burn of the sole of the foot). Cavovarus deformity has been long associated with neurological disease such as cerebral palsy, Charcot-Marie-Tooth (CMT) disease or other hereditary sensory and motor neuropathies (myelodysplasia, Friedreich ataxia, etc). CMT disease results from defects in the genetic code for the protein of the peripheral myelin sheath and is classified into subtypes varying in progression. CMT IA is the most common form including peripheral nerve myelin degeneration and decreased motor nerve conduction. In most cases, the disease process is progressive rather than static; therefore, the deformities worsen and surgical treatment must be considered to prevent the progression to a fixed and symptomatic deformity.3 However, in recent years, a mild variation of the cavovarus deformity has been increasingly observed to exist without an identifiable underlying deficit.4 In our experience, this primary pes cavus (idiopathic) is diagnosed by elimination in more than half the cases and most authors believe that it is the consequence of a latent neurological disorder. Thus, neurological disorders must be looked for in the family history and clinical and electrophysiologica evaluation of the patient is necessary to eliminate any very subtle neurological lesion.