Cavus – Charcot Marie Tooth

Modern Study Review (AI-Generated)

High-Yield Summary

Pes cavus in Charcot-Marie-Tooth (CMT) disease results from progressive distal muscle imbalance, leading to a complex deformity characterized by forefoot cavus, hindfoot varus, and claw toes. Early recognition and multidisciplinary management are essential to maintain foot stability, function, and pain control. Surgical intervention aims to restore a plantigrade, balanced foot, prioritizing soft tissue procedures before bony corrections, with tendon transfers to rebalance muscular forces. Given the progressive nature of CMT, timing of surgery and long-term follow-up are critical to optimize outcomes and minimize recurrence.

Key Diagnostic Findings

Anatomy

• Muscle Weakness Pattern: Intrinsic foot muscles, peroneus brevis, and tibialis anterior weaken progressively.
• Muscle Overactivity: Peroneus longus pulls the first ray into plantarflexion; tibialis posterior inverts the hindfoot causing varus.
• Secondary Effects: Long toe extensors compensate for weak dorsiflexors, causing claw toe deformities.

Clinical Presentation

• High-arched foot (pes cavus) with forefoot cavus and hindfoot varus.
• Clawing of toes due to intrinsic muscle weakness and extensor substitution.
• Gait instability, pain, and progressive deformity.
• Possible associated hip dysplasia in CMT patients (important to screen).

Imaging

• Weight-bearing foot radiographs to assess:
• First ray plantarflexion deformity.
• Hindfoot varus rigidity.
• Forefoot valgus and metatarsal alignment.
• MRI or ultrasound may assist in soft tissue assessment if needed.

Classification Systems

• No universally accepted classification specific to CMT cavus deformity; deformity is described clinically and radiographically by the degree of flexibility and involvement of forefoot, hindfoot, and toes.
• Modern approach emphasizes flexible vs. rigid deformity to guide treatment.

Current Gold Standard Treatment

Non-operative Indications and Treatment

• Early-stage, flexible deformities without significant pain or instability.
• Multidisciplinary care involving neurologists and physiotherapists.
• Strengthening of remaining functional muscles, aerobic conditioning, and stretching.
• Orthotic management:
• Ankle-foot orthoses (AFO) to prevent equinus contracture.
• Custom orthotics to accommodate plantarflexed first ray and support hindfoot varus.

Operative Indications and Treatment

• Persistent pain, instability, or progressive deformity despite conservative care.
• Rigid deformities uncorrectable by soft tissue procedures.
• Surgical strategy:
1. Soft Tissue Procedures (for supple deformities):
2. Plantar fascia and medial structure releases.
3. Peroneus longus to peroneus brevis tendon transfer.
4. Extensor hallucis longus (EHL) transfer and Jones fusion for hallux clawing.
5. Flexor-to-extensor transfers for lesser toe clawing.
6. Achilles tendon lengthening after soft tissue balancing.
7. Bony Procedures (for rigid deformities):
8. Dorsal closing wedge osteotomy of first metatarsal for plantarflexed ray.
9. Additional osteotomies for other metatarsals if needed.
10. Lateral wedge (Dwyer) osteotomy for rigid hindfoot varus.
11. Triple arthrodesis as salvage for severe, fixed deformities.
12. Tendon Transfers:
13. Tibialis posterior transfer dorsally to cuboid or through interosseous membrane to reduce varus.
14. Possible tibialis anterior transfer laterally (caution: often weak in CMT).

Modern Complications & Outcomes

Complications

Outcomes

• Early surgical intervention aiming for a stable, plantigrade foot improves function and reduces pain.
• Soft tissue procedures alone may suffice in flexible deformities; rigid deformities require osteotomies or arthrodesis.
• Tendon transfers improve dynamic balance but must be carefully selected based on muscle strength.
• Long-term follow-up is essential due to disease progression and risk of recurrence.
• Multidisciplinary care optimizes rehabilitation and functional outcomes.

Classic Clinical Notes

Cavus/CMT

Approach to Pes Cavus – CMT

• The pes cavus associated with CMT is caused by progressive weakness of intrinsics, peroneus brevis, and tibialis anterior.
• The first ray is pulled down by peroneus longus; the hindfoot swings into varus by the force of tibialis posterior to stabilize the weightbearing foot (tripod), and the long toe extensors try to work as ankle dorsiflexors, eventually causing clawing.
• Typical deformities in CMT: hindfoot varus, cavus deformity (mainly through the forefoot), and forefoot valgus.

Management

• Involve neurologist and physiotherapist.
• Strengthening, aerobic conditioning, and stretching exercises.
• Watch out for hip dysplasia in the CMT patient.

Orthotics

• AFO to prevent equinus contracture.
• Orthotics to accommodate the plantarflexed first ray and support the hindfoot.

Treatment Principles

• Goal: Get the foot stable, plantigrade, and painless.
• Soft tissue procedures for flexible/correctable deformities.
• Bony procedures for inflexible deformities.
• Start with soft tissue procedures, then osteotomies if correction is incomplete.
• Tendon transfers to balance the foot.

Surgery

• Previously, triple arthrodesis was the default for advanced deformities; now early intervention is preferred to improve function and prevent painful foot development.
• Younger patients have higher risk of recurrence due to disease progression.

Soft Tissue Procedures

• Release plantar fascia and medial structures: abductor hallucis, long and short plantar ligaments, quadratus plantae.
• Transfer peroneus longus to peroneus brevis.
• Jones IP fusion and transfer of EHL to metatarsal neck for hallux clawing.
• Girdleston-Taylor flexor to extensor transfers for lesser toe clawing; or EDL tenotomies + IP fusions.
• Lengthen heel cord after other soft tissue procedures.

Bony Procedures

• Rigid first ray plantarflexion: dorsal closing wedge osteotomy.
• Multiple dorsal closing wedge osteotomies if other metatarsals are flexed down.
• Rigid hindfoot varus: lateral wedge osteotomy (Dwyer).
• Triple arthrodesis for combined hindfoot and forefoot deformities.

Tendon Transfers

• Transfer tibialis posterior to dorsum of foot through interosseous membrane or around ankle to cuboid (to reduce varus).
• Consider tibialis anterior transfer to lateral foot—caution as tibialis anterior is often weak.

Last Updated on January 25, 2026 by orthonet