The deformity can be plantaris, equinocavus and calcaneocavus. The primary cause could be plantarflexion of first ray due to weakness of tibialis anterior in plantaris cavus foot. In equinocavus foot there is tight heel cord but also tibialis posterior contracture. In calcaneocavus foot the heel cord is weak and therefore the os calcis is dorsiflexed.
Following are some common causes of pes cavus:
- Hereditary sensory motor neuropathy (HSMN)
- Cerebral palsy
- Friederich’s ataxia
- Post traumatic
- Spinal dysraphism
- Muscular dystrophy
The Coleman block test assesses whether the cavovarus foot is mobile. This helps in planning treatment. Patients with this condition get pain in the ball of the big toe and also on the heel. They also can get recurrent sprain. A thorough neurological examination is a must.
The treatment varies according to the severity of the deformity. This could involve midfoot and hindfoot osteotomy with tibialis posterior transfer and plantarfasciotomy. Also lateral shift os calcis osteotomy can be combined with dorsiflexion basal 1st metatarsal osteotomy. Severe deformities can be treated with Ilizarov or Taylor Spatial Frame.