What is a Cavovarus Deformity? How and Why It Happens

A cavovarus deformity is a complex foot condition characterized by an abnormally high arch (cavus) and an inward-turning heel (varus). This alignment causes the foot to be rigid and can lead to pain, instability, and difficulty walking. Individuals with this condition often place excessive weight on the outer edge of their foot.

Cavovarus deformities are most often caused by underlying neurological conditions that create muscle imbalances in the foot and ankle. Common causes include:

• Charcot-Marie-Tooth (CMT) disease: This is the most frequent cause. It's an inherited neurological disorder that affects the peripheral nerves, leading to muscle weakness and atrophy in the limbs.
• Spinal cord injuries: Trauma to the spinal cord can disrupt nerve signals to the foot muscles.
• Poliomyelitis: Though rare now, post-polio syndrome can lead to muscle imbalances that cause the deformity.
• Clubfoot: If a congenital clubfoot is not fully corrected or recurs, it can result in a cavovarus foot.
• Nerve entrapment: Compression of nerves in the leg can lead to the muscle weakness that causes the foot's shape to change.

In some cases, the deformity can be idiopathic (having no known cause) or develop after a severe injury like a fracture.

Because of the foot's abnormal structure, people with a cavovarus deformity are at higher risk for:

• Ankle sprains: The inward tilt of the foot increases the likelihood of rolling the ankle.
• Stress fractures: Excessive pressure on the outer bones of the foot (like the fifth metatarsal) can lead to fractures.
• Plantar fasciitis: The high arch can put extra strain on the plantar fascia.
• Painful calluses: These can form on the ball and outer edge of the foot due to uneven weight distribution.