02/06/2026
Pes cavus
1. What is the most common underlying cause of pes cavus in children and adolescents?
Answer: A neurologic disorder should always be suspected. The most common cause is Charcot-Marie-Tooth Disease. Approximately two-thirds of symptomatic cavus feet have an underlying neurologic etiology.
2. Why is a unilateral pes cavus more concerning than a bilateral deformity?
Answer: Unilateral pes cavus raises suspicion for a spinal cord lesion such as Tethered Cord Syndrome, spinal tumor, or other central neurologic pathology. MRI evaluation may be indicated.
3. What is the purpose of the Coleman block test?
Answer: The Coleman block test determines whether hindfoot varus is flexible or rigid. If the heel corrects to neutral when the first ray is unloaded, the hindfoot varus is flexible and secondary to a plantarflexed first ray.
4. A patient has cavovarus foot with a positive Coleman block test. Which osteotomy is commonly considered?
Answer: A dorsiflexion osteotomy of the first metatarsal may be performed to address the plantarflexed first ray causing the hindfoot varus.
5. Which muscle imbalance is classically responsible for the development of cavovarus deformity in Charcot-Marie-Tooth disease?
Answer: Relative overpull of the tibialis posterior and peroneus longus with weakness of tibialis anterior and peroneus brevis leads to plantarflexion of the first ray and progressive cavovarus deformity.
6. What radiographic measurement is commonly increased in pes cavus on a lateral foot radiograph?
Answer: The Meary angle (talo–first metatarsal angle) is increased. Normally the axes are nearly collinear; increased angulation reflects cavus deformity.
7. What is the "peek-a-boo heel sign"?
Answer: When viewing the patient from the front, the heel pad is visible medially due to hindfoot varus. It is a classic clinical sign of cavovarus foot.
8. Why do patients with pes cavus frequently develop lateral ankle instability?
Answer: Hindfoot varus shifts weight-bearing laterally, increasing stress on the lateral ligament complex and predisposing to recurrent ankle sprains and chronic instability.
9. What is the role of tendon transfers in cavus foot reconstruction?
Answer: Tendon transfers rebalance muscle forces rather than simply correcting bone deformity. Examples include transferring peroneus longus to peroneus brevis or transferring posterior tibial tendon in selected cases.
10. When is triple arthrodesis indicated in pes cavus?
Answer: Triple arthrodesis is generally reserved for severe rigid cavovarus deformity, advanced degenerative changes, failed previous reconstruction, or neuromuscular disease when joint-preserving procedures are unlikely to succeed.
Bonus Expert-Level Question
In a cavovarus foot, which deformity typically occurs first: hindfoot varus or plantarflexion of the first ray?
Answer: In many neuromuscular cavovarus feet, especially in Charcot-Marie-Tooth disease, plantarflexion of the first ray occurs first. The hindfoot varus develops secondarily as compensation, which is demonstrated by correction of the heel during the Coleman block test.
