A pes cavus is characterised by a high arch of the foot and can occur when the arch is in a weight-bearing (standing) position and doesn’t drop down or flatten to disperse the shock when walking or running.
Symptoms may include:
- Lateral ankle instability
- Knee and lower back pain
The cause and deforming mechanism underlying pes cavus are 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.
Three main types of pes cavus are regularly described in the literature: pes cavovarus, pes calcaneocavus, and ‘pure’ pes cavus. The three types of pes cavus can be distinguished by their aetiology, clinical signs and radiological appearance.
- Pes cavovarus, the most common type of pes cavus, is seen primarily in neuromuscular disorders such as Charcot-Marie-Tooth disease and, in cases of unknown aetiology, is conventionally termed ‘idiopathic’. Pes cavovarus presents with the calcaneus in varus, the first metatarsal plantarflexed, and a claw-toe deformity. Radiological analysis of pes cavus in Charcot-Marie-Tooth disease shows the forefoot is typically plantarflexed in relation to the rearfoot.
- pes calcaneocavus foot, which is seen primarily following paralysis of the triceps surae due to poliomyelitis, the calcaneus is dorsiflexed and the forefoot is plantarflexed. Radiological analysis of pes calcaneocavus reveals a large talo-calcaneal angle.
- pes cavus, the calcaneus is neither dorsiflexed nor in varus and is highly arched due to a plantarflexed position of the forefoot on the rearfoot. A combination of any or all of these elements can also be seen in a ‘combined’ type of pes cavus that may be further categorized as flexible or rigid.