Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

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Cavus Foot

Basics
Description
Cavus foot is defined by an elevation of the medial longitudinal arch, often with an associated deformity of the hindfoot or forefoot .

Epidemiology
Incidence
Cavus feet are common and may be associated with several underlying conditions that affect the muscle balance of the foot.
 
Risk Factors
  • Neuromuscular disorders
  • Trauma
  • Connective-tissue disorders
  • Congenital deformities
Genetics
  • Several of the diseases responsible for the development of cavus feet are hereditary.
  • The most common hereditary cause is Charcot-Marie-Tooth disease, which is autosomal dominant.
Pathophysiology
Neuromuscular disorders are the etiologic factor for most cavus foot deformities, causing muscle imbalance that leads to atrophy or fibrosis, deformity, and joint contractures.
 
Etiology
  • Causes include:
    • Muscle imbalance, such as peroneus longus or posterior tibialis overpull
    • Weakness of the intrinsic muscles of the foot with overpull of the long flexor tendons
    • Connective-tissue disorders, such as Marfan syndrome
Associated Conditions
  • Charcot-Marie-Tooth disease
  • Friedreich ataxia
  • Spina bifida, syringomyelia
  • Diabetic neuropathy
  • Poliomyelitis
  • Previous compartment syndrome of the leg or foot
  • Partially treated clubfoot
  • Idiopathic clubfoot
  • Marfan syndrome
  • Beal syndrome
Diagnosis
Signs and Symptoms
  • High arch
  • Calluses on forefoot or hindfoot
  • Difficulty with shoe wear
  • Patient:
    • May have heel varus or plantarflexion of the 1st metatarsal
    • May be asymptomatic
    • May complain of metatarsalgia (pain under metatarsal head region)
    • May develop recurrent ankle instability and/or sprains secondary to severe varus heel malalignment
Physical Exam
  • Measure the motor strength of all muscles crossing the ankle on both legs.
  • Look for associated claw-toe deformities.
  • Assess for plantar fascia contracture.
  • Check reflexes and sensation to light touch.
  • Examine the upper extremities, especially for intrinsic wasting.
  • Observe the spine for dimples, markings, and scoliosis.
Tests
  • Coleman block testing determines whether the hindfoot varus is flexible or rigid .
    • The patient stands on a block with the first metatarsal and hallux suspended freely in the air.
    • This position eliminates contribution from a relatively plantarflexed 1st metatarsal, which in turn causes varus alignment of hindfoot.
    • In a flexible cavus deformity, Coleman block testing removes forefoot contribution and allows the hindfoot varus to correct.
    • In a rigid deformity, no hindfoot correction occurs.
Lab
Electromyography and nerve conduction studies are helpful in diagnosing Charcot-Marie-Tooth disease, hereditary motor sensory neuropathies, and lumbar radiculopathy.
 
Imaging
  • Standing radiographs of the foot should be obtained to evaluate the calcaneal pitch angle (angle between the calcaneus and the floor) and the Meary angle (angle between the talus and the 1st metatarsal).
  • As part of the workup for undiagnosed cavus foot deformity, plain radiographs and MRI of the spine may be indicated to identify occult abnormalities.
Differential Diagnosis
Muscle atrophy may cause the arch to appear higher.
 
Treatment
General Measures
  • No treatment is indicated if the patient is asymptomatic and the skin is in good condition.
  • A padded insole with an arch support and/or metatarsal bar may relieve metatarsalgia.
  • A lateral heel wedge may help correct a flexible hindfoot varus deformity.
  • A brace may help stabilize a severely weakened cavus foot or concurrent chronic ankle instability.
  • Stretching may help prevent worsening deformity and maintain flexibility.
  • In general, cavovarus foot is tolerated poorly because of progressive deformity, shoe wear difficulties, ankle instability, and arthritis.
Special Therapy
Physical Therapy
  • Stretching of a tight plantar fascia and of other tight muscles may help slow progression of the condition.
  • Muscle strengthening, proprioceptive training, and closed-chain balance exercises may help if the cavovarus deformity has led to ankle instability.
Surgery
  • Usually, surgery is indicated for progressive deformity, recalcitrant pain, chronic ankle instability, difficulty with shoe wear, or rigid deformity with resultant arthritis.
  • Careful examination helps to identify the components of the deformity and the degree of flexibility or rigidity, leading to a customized stepwise surgical plan to address all aspects.
  • Flexible deformities can be addressed with soft-tissue rebalancing procedures, whereas rigid deformities require bony osteotomies or arthrodesis (fusion) procedures for correction.
  • Plantar fasciotomy may help lower the high arch.
  • Midfoot and metatarsal osteotomies are needed for a rigid cavus foot .
  • A lateral closing-wedge calcaneal osteotomy is performed if the heel varus is rigid.
  • Tendon lengthening procedures or tendon transfers are necessary to treat muscle imbalance.
  • Chronic ankle instability is addressed by ligament reconstruction and often concomitant tenodesis stabilization.
  • Triple arthrodesis is reserved mainly as a salvage procedure if other surgical treatments fail or if the patient has painful arthritis.
Follow-up
  • Patients with a cavus foot deformity must be followed regularly by an orthopaedic surgeon for progression of the deformity or muscle weakness.
  • Progression may necessitate earlier reconstructive surgery to avoid fusion.
Issues for Referral
All patients with symptomatic cavus feet should be referred for orthopaedic consultation.
 
Prognosis
  • Patients with cavus feet secondary to neuropathy usually experience progressive deformity over time.
  • Patients with diabetes and Charcot-Marie-Tooth disease may lose protective sensation and develop neuropathic ulcerations that eventually lead to osteomyelitis and amputation.
  • Therefore, great care and attention must be paid to appropriate orthoses and shoe wear to prevent abnormal skin pressure from occurring.
Miscellaneous
Codes
ICD9-CM
  • 754.59 Cavovarus foot
  • 754.71 Cavus foot
FAQ
Q: What is the cause of most cavus feet?
A: Neurologic disorders cause many cavus foot deformities secondary to muscle imbalance between plantarflexor-invertors and dorsiflexor-evertors.
 
Q: When is surgery indicated for cavus foot deformity?
A: Surgery is indicated in symptomatic cavus feet that show progressive deformity, ankle instability, claw toes, and metatarsalgia or failure of shoe wear modifications and orthotic use.

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