Overview

Charcot-Marie-Tooth disease (CMT), also called hereditary motor and sensory neuropathy (HMSN), is the most common inherited peripheral neuropathy. Orthopaedic presentation is usually a progressive cavovarus foot in a child or young adult.

Aetiology and pathology

CMT1 is demyelinating. CMT1A is caused by a duplication of the PMP22 gene on chromosome 17 and is autosomal dominant. It is the most common form.
CMT2 is axonal, with MFN2 mutations the most frequent cause.
X-linked forms involve the GJB1 (connexin 32) gene.
Length-dependent neuropathy affects the longest nerves first, so the foot and then the hand are involved.
Muscle imbalance drives the deformity. Tibialis anterior and peroneus brevis weaken early, while peroneus longus and tibialis posterior are relatively preserved.
Unopposed peroneus longus plantarflexes the first ray. The forefoot pronates and the hindfoot is driven into varus on weight bearing.
Intrinsic weakness and recruitment of the long toe extensors to assist dorsiflexion produce claw toes.

Clinical features

Family history, clumsiness, frequent ankle sprains, lateral foot pain and callosities under the first and fifth metatarsal heads.
High arch with hindfoot varus. The medial heel is visible from the front, the peek-a-boo heel sign.
Distal calf wasting, foot drop and a high stepping gait.
Reduced or absent ankle reflexes and stocking sensory loss.
Intrinsic wasting of the hand in later disease.
Coleman block test assesses hindfoot flexibility. A block under the lateral foot lets the first ray drop. If the heel corrects to valgus, the varus is forefoot driven and the hindfoot is flexible.

Imaging and investigation

Weight-bearing lateral foot radiograph shows an increased Meary angle, high calcaneal pitch and a see-through sinus tarsi.
Weight-bearing AP ankle and hindfoot alignment views show varus and any ankle arthritis.
Nerve conduction studies separate demyelinating from axonal types. Genetic testing confirms the subtype.
Unilateral cavus should prompt spinal MRI to look for a cord lesion.

Management

Non-operative care includes stretching, lateral posted orthoses, accommodative footwear and ankle-foot orthoses for foot drop.
Surgery aims for a plantigrade, balanced foot and is tailored to flexibility and muscle strength.
Soft tissue procedures include plantar fascia release, peroneus longus to brevis transfer and tibialis posterior transfer through the interosseous membrane for foot drop.
The Jones procedure transfers EHL to the first metatarsal neck with fusion of the hallux interphalangeal joint.
Bony procedures include dorsiflexion osteotomy of the first metatarsal and a lateralising or Dwyer closing wedge calcaneal osteotomy for residual hindfoot varus.
Triple arthrodesis is reserved for rigid deformity or arthritis, given long-term adjacent joint degeneration.

Complications

Recurrence with ongoing progression of the neuropathy.
Undercorrection, overcorrection and transfer metatarsalgia.
Ankle and adjacent joint arthritis, especially after triple arthrodesis.
Wound problems and nerve injury.

Exam traps

Explain the deformity in terms of which muscles are weak and which are preserved.
Always perform and interpret the Coleman block test.
Balance tendons as well as correcting bone, or the deformity recurs.
Look at the hands, spine and family members.

References

1. Pareyson D, Marchesi C. Diagnosis, natural history, and management of Charcot-Marie-Tooth disease. Lancet Neurol. 2009, 8(7), 654-67.

2. Coleman SS, Chesnut WJ. A simple test for hindfoot flexibility in the cavovarus foot. Clin Orthop Relat Res. 1977, (123), 60-2.

3. Ward CM, Dolan LA, Bennett DL, Morcuende JA, Cooper RR. Long-term results of reconstruction for treatment of a flexible cavovarus foot in Charcot-Marie-Tooth disease. J Bone Joint Surg Am. 2008, 90(12), 2631-42.

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 17 October 2026.