Review Question - QID 3144

A plantarflexed first ray is the initial pathology noted in a cavovarus foot deformity. It is driven by an increase in peroneus longus tone relative to the tibialis anterior.

This patient is presenting with the history and clinical findings of Charcot-Marie-Tooth (CMT) disease. Symptoms can vary, but the development of cavovarus deformity as seen in the clinical radiograph is common. The initial deforming force is the result of a weak anterior tibialis being overpowered by the unaffected peroneus longus, bringing the first ray into a plantarflexed position. This forces the hindfoot into varus position leading to lateral column overload and pain. The weakened tibialis anterior can also lead to a foot-drop deformity, and compound the gait difficulties.

Ward et al. reviewed 25 consecutive patients with CMT. They discuss improved outcomes in the treatment of flexible cavovarus foot deformities with soft-tissue and osteotomy procedures compared to triple arthrodesis at an average of 26 years postoperatively. They conclude that soft tissue-based procedures result in lower rates of degenerative changes and reoperations as compared with those reported at the time of long-term follow-up of patients treated with triple arthrodesis.

Figure A is a clinical radiograph of a patient with CMT demonstrating significant cavus.

Incorrect answers:
Answer 1: The foot deformity in CMT is not driven by a weakened gastrocnemius-soleus complex.
Answer 2: The posterior tibial tendon overpowers the peroneus brevis in the cavovarus foot.
Answer 3: The peroneus longus overpowers the tibialis anterior resulting in a plantarflexed first ray.
Answer 5: Clawing of the toes results from weak intrinsics.