Pes cavus

Principal authors: Louise Crawford, Jim Barrie

Latest evidence check Feb 2010.

Pes cavus is generally thought of as a neurologically-determined deformity due to muscle imbalance. However, neurological signs are not always present, and ssome patients deny any family histor of congenital neurological diseases.

Brewerton (1962, before MRI and with less accurate electrophysiology) found neurological diagnoses in 70% of patients with cavus feet, only half of which were known prior to referral.

Nagai (2006), using electrophysioloical testing and genetic testing for duplication on chromosome 17, found that 116/148 (78%) children with bilateral cavovarus feet had Charcot-Marie-Tooth disease, and in those with a family hostory of CMT 91% had the syndrome.

In our experience, and despite access to MRI, modern neurophysiology and genetic testing, we have found fewer definite neurological diagnoses than Brewerton or Nagai. In Blackburn adults, about 30% have a known diagnosis at presentation. We have made a diagnosis in about 10-15% of the others, all of whom had neurological abnormalities, family history, asymmetric feet or scoliosis. In practice, adults presenting without a known diagnosis will often not have one. The most important reason for establishing the cause is to decide whether the deformity is likely to be progressive as this is likely to affect management of the foot deformity.

Of the 70% with neurological diagnoses in Brewerton's series, hereditary motor sensory neuropathies (HMSN) accounted for half. HMSN is a complex group of congenital peripheral neuropathies, some of which have well-understood genetic and molecular bases, while others are described mainly on clinical findings in rare patient groups. It is the most common cause of the cavus foot.