Cavus Deformity

Definition: Abnormal elevation in longitudinal arch Results in decreased plantar weight-bearing area Places stress on metatarsal heads Generalized stiffness of joints is common - decreased range of motion Hindfoot often in varus position Clawing of toes Altered gait pattern Increased pressure on lateral foot, then 1^st metatarsal head Etiology: Charcot-Marie-Tooth disease Congenital clubfoot Anterior horn cell diseases Poliomyelitis most common Spinal cord tumor Friedrich’s ataxia Cerebral palsy Muscular dystrophy Sequelae of calf compartment syndrome Idiopathic (commonly runs in families) Anatomy: Posterior cavus = calcaneus dorsiflexion pitch of 40° (Normal is 20°) Anterior cavus = forefoot equinus (plantarflexed) Combined cavus = both calcaneus and forefoot components

Cavus foot Plantarflexed first ray in Charcot-Marie-Tooth Disease

Symptoms/Signs:

• Compromised activity level secondary to increased pressure over metatarsal heads
• Ambulation abnormalities in people with neurological disorders
• Calf atrophy--associated with Charcot-Marie or clubfoot
• Flexiblilty and location of deformity – hindfoot vs midfoot, lesser toes, plantar fascia
• Coleman block test determines if heel varus is fixed, or flexible and due only to plantarflexed first ray

Imaging:

• Bilateral weightbearing foot and ankle radiographs

Treatment:

Calcaneus lateral closing wedge osteotomy for correction of hindfoot varus position of cavus foot deformity

• Conservative, nonoperative treatment is adequate for most cases of cavus foot:
• Soft-soled shoes for mild deformity
• Deep shoes for claw-toe deformities
• Arch supports to decrease stress on metatarsal heads

oSurgical treatment involves correction of 1^st metatarsal plantarflexion contracture, tight plantar fascia, and varus calcaneus deformity:

• Plantar fascia release
• Dorsiflexion osteotomy of 1^st metatarsal
• Lateral closing wedge osteotomy of calcaneus (Dwyer procedure, right)
• More severe cases involve tendon transfers:

-Peroneus longus tendon to peroneus brevis

-Lengthening of posterior tibial tendon