Charcot-Marie-Tooth disease (CMT) is the most common inherited peripheral neuropathy, affecting approximately 1 in 2,500 people. Its foot manifestations — progressive cavus (high arch) deformity, hammertoes, foot drop, and ankle instability — are often the first and most persistent symptoms, and podiatric management plays a central role throughout the patient’s lifetime.

What Is Charcot-Marie-Tooth Disease?

CMT is a group of hereditary motor and sensory neuropathies caused by mutations in genes encoding myelin proteins or axonal proteins of peripheral nerves. The resulting muscle weakness and sensory loss follow a length-dependent pattern — longest nerves affected first, meaning foot and lower leg involvement precedes hand and forearm involvement. CMT1A (PMP22 gene duplication, chromosome 17) is the most common subtype, accounting for approximately 50% of cases.

Classic Foot Presentation of CMT

• Pes cavus (high arch): Progressive elevation of the medial longitudinal arch from imbalance between intrinsic foot muscles and extrinsic muscles; the plantar fascia shortens and thickens as the arch rises
• Hammertoes / claw toes: Intrinsic muscle weakness allows long flexors and extensors to dominate; all MTP joints develop claw deformity; pressure ulcers form at dorsal toe knuckles
• Foot drop (steppage gait): Tibialis anterior weakness causes inability to dorsiflex the foot during swing phase; the patient compensates by excessively lifting the knee (steppage gait) or circumducting the leg
• Ankle instability: Peroneal muscle weakness (peroneus longus before brevis) creates inversion instability; lateral ankle sprains are frequent and often the presenting complaint in adolescence
• Metatarsal head pressure ulcers: Prominent metatarsal heads from cavus posture combined with sensory loss creates forefoot pressure ulcer risk
• Small foot / shoe fitting difficulty: The cavus foot is narrow and high-arched; standard shoes cause pressure at lateral heel and fifth metatarsal

How CMT Foot Deformity Progresses

The classic sequence in CMT foot deformity: early peroneal weakness → subtalar supination → plantar fascia contracture → cavus arch elevation → metatarsal head prominence → hammertoe formation → rigid deformity. This progression is slow (years to decades) and variable between patients, even within the same family with identical genetic mutations. Regular podiatric monitoring every 6–12 months allows intervention before deformity becomes fixed.

Conservative Management

Conservative care for CMT foot manifestations is lifelong and evolves as deformity progresses. The primary goals are pressure redistribution, fall prevention, and maintenance of ambulatory function.

• Custom orthotics (ankle-foot orthosis lateral post): The CMT cavus foot requires a rigid custom orthotic with lateral heel posting to resist supination; standard arch supports are contraindicated (they force a foot that is already over-supinated into more supination)
• Ankle-foot orthosis (AFO) for foot drop: Carbon fiber dynamic AFO (e.g., Richie Brace or custom carbon AFO) controls foot drop while allowing some ankle motion; rigid AFO for severe weakness; custom fitting essential due to narrow CMT foot shape
• Extra-depth shoes with wide toe box: Accommodates prominent metatarsal heads and claw toes; reduces dorsal pressure on hammertoes; Orthofeet, Drew, and New Balance wide-width options are commonly appropriate
• Toe pads / crest pads: Flexible hammertoe crest pads reduce dorsal IP joint pressure from shoe counter; moleskin protection for at-risk pressure areas
• Fall prevention program: Ankle strengthening within available range (peroneals if partially functional), proprioception training, and assistive device evaluation; fall risk in CMT is significantly elevated

Surgical Management

Surgical intervention is considered when deformity causes pain, pressure ulceration, falls, or progressive loss of ambulatory function despite optimal conservative management. Timing matters: early intervention on flexible deformity has better outcomes than late intervention on rigid deformity.

• Plantar fascia release: For early cavus with plantar fascia contracture; releases the deforming force driving arch elevation
• Peroneus longus to brevis transfer: Transfers the plantar-flexing force of peroneus longus (which drives metatarsal head prominence in CMT) to peroneus brevis (eversion function); reduces forefoot pressure significantly
• Dorsiflexion osteotomy (1st metatarsal): Corrects plantar-flexed 1st metatarsal that drives the cavus deformity
• Hammertoe correction: PIP joint fusion for rigid hammertoes with pressure ulcer risk
• Calcaneal osteotomy: Lateral displacement calcaneal osteotomy for heel varus (the typical rearfoot alignment in CMT cavus)
• Triple arthrodesis: For severe rigid deformity — fusion of subtalar, talonavicular, and calcaneocuboid joints to create a plantigrade, stable foot; last resort but provides reliable correction
• Tibialis posterior transfer for foot drop: The tibialis posterior is rerouted to the dorsum of the foot through the interosseous membrane, providing active dorsiflexion when tibialis anterior is absent

The Most Important Podiatric Principle in CMT

The most important principle: standard “flat foot” orthotics and motion-control shoes are harmful in CMT. The CMT foot is a cavus (high-arch) foot with supination tendency — exactly the opposite of the pronating flatfoot that most OTC insoles are designed for. Applying a medial arch support to a CMT foot that is already over-supinated drives more supination, worsens lateral ankle instability, and accelerates metatarsal head prominence. Every CMT patient requires custom orthotics designed by a podiatrist who understands the cavus biomechanics.

Podiatric Care for CMT at Balance Foot & Ankle

Dr. Biernacki has experience managing CMT foot deformity across all stages. Initial evaluation includes gait analysis, cavus deformity assessment (Coleman block test), sensory testing, and footwear review. Custom orthotics are fabricated with appropriate lateral posting for CMT biomechanics. Surgical planning, when indicated, considers the stage of deformity and the patient’s long-term ambulatory goals.

Schedule a same-day evaluation or call (810) 206-1402. Serving Howell, Bloomfield Hills, and all of southeast Michigan.