Review Question - QID 973

The etiology of the abnormal foot posture in Charcot-Marie-Tooth disease usually results from peroneus longus overpowering tibialis anterior. The peroneus longus acts to plantarflex the first metatarsal raising the arch height and tilting the hindfoot into varus. Thus the Coleman block test allows one to check the hindfoot flexibility by eliminating the effect of the plantarflexed 1st ray and observing its effect on the hindfoot.

Additionally, the peroneus brevis is weak, allowing it to be over-powered by the posterior tibialis resulting in adduction of the foot and varus.

Bilateral pes cavovarus is the most common pathologic foot deformity seen with Charcot-Marie-Tooth disease. A passively correctable, and thus flexible, cavovarus foot may be appropriately treated with plantar fascial release, dorsal closing wedge osteotomy of the first metatarsal, and peroneus longus to peroneus brevis tendon transfer. A calcaneal osteotomy may also be indicated.

Holmes and Hansen present a Level 5 review of Charcot-Marie-Tooth disease. They report that the specific components of the disease process includes hindfoot varus, anterior or forefoot cavus, and often clawtoes. The study by Ward looks at long-term follow up of Cavovarus foot correction with (in part) peroneus longus to brevis transfer to eliminate that muscle imbalance.