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The Adolescent Cavus Foot
- Progressive cavus foot deformity may be the first sign of other pathologic conditions that must be identified with hereditary sensorimotor neuropathy type I (Charcot-Marie-Tooth), the most prevalent neuromuscular cause.
- •Treatment for the foot is generally symptomatic.
History
- •A family history of any neurologic condition should be defined.
- •Clinical signs rarely manifest before age 3 years.
- •A visual deformity or a limp is the common symptom in the young child.
- •Pain or shoe wear problems occur later.
- •Neurologic problems such as bowel or bladder incontinence and subtle weakness signs such as problems with stairs must be asked about specifically.
Physical Examination
- •The foot shows a progression of deformity.
- •Toe dorsiflexion and clawing
- •Plantar fascia contraction and increased arch height
- •First metatarsal plantarflexion
- •Asymmetric muscle weakening, especially of the peroneals
- •Hindfoot varus as the first metatarsal plantarflexion increases
- •Rigidity of the foot with maturity Cavus foot. Lateral view of the foot demonstrating the clawing of the toes, plantar fascia contraction, and increased arch height leading to first metatarsal plantarflexion.(From Sabir M, Lyttle D: Pathogenesis of pes cavus in Charcot-Marie-Tooth disease, Clin Orthop Relat Res 175:173-178, 1983.)
- •Comprehensive neurologic examination, including tone assessment, reflexes, strength, and motor control
- •Spine examination for scoliosis or other deformity
- •Lower extremity examination to assess length, alignment, and development
Imaging
- •Plain radiographs define the degree and location of the deformity.
- •Standing radiographs are recommended.
- •The position of the calcaneus is usually dorsiflexed relative to the tibia, indicating that the Achilles tendon is not shortened.
- •Magnetic resonance imaging of the spinal axis, including the entire spinal cord if upper motor neuron findings are present
- •Magnetic resonance imaging of the brain if indicated by symptoms and findings
Additional Tests
- •Nerve conduction studies may help to classify the condition.
- •Serology studies
- •Hereditary sensorimotor neuropathy type IA is inherited in an autosomal dominant manner and is caused by duplication of the gene for peripheral myelin protein 22 (PMP-22) in chromosome region 17p11.2.
- •More than 18 genes and 11 additional loci harboring candidate genes have been associated with hereditary sensorimotor neuropathy and related peripheral neuropathies.
Differential Diagnosis
- •Many conditions have been associated with cavus foot deformity and are grouped by cause below.
- Modified from Schwend RM, Drennan JC. Cavus foot deformity in children. J Am Acad Orthop Surg. 2003;11(3):201–211.Conditions Associated with Cavus Foot Deformity Grouped by CauseCentral Nervous System
- Spastic hemiplegia
- Friedreich ataxia
- Brain tumors
- Diastematomyelia
- Myelodysplasia
- Syringomyelia
- Poliomyelitis
- Spinal cord tumors
- Intrathecal lipoma
- Tethered cord syndrome
- Guillain-Barré syndrome
- Hereditary sensorimotor neuropathy
- Polyneuritis
- Small muscular atrophy
- Atypical polyneuritis
- Neuromuscular choristoma
- Isolated injuries to selected nerves, muscles, and tendons
- Clubfoot or residual clubfoot deformity
- Idiopathic
- •Hereditary sensorimotor neuropathy type I is the most prevalent neuromuscular cause and is commonly known as Charcot-Marie-Tooth disease type I.
Treatment
At Diagnosis
- •Determination of the cause if there is one
- •Maintain flexibility with stretching as possible
- •Shoe modifications or foot orthosis if symptomatic
Later
- •Flexibility of the deformity determines treatment options
- •Surgical reconstruction if severely symptomatic
When to Refer
- •If unable to determine the etiology
- •If foot is rigid or symptomatic
Prognosis
- •Depends on the etiology but usually progressive deformity and stiffness
- •Most forms are treatable and do not prevent light-duty daily activities.
Troubleshooting
- •Many of the conditions that cause cavus foot deformity also cause scoliosis and hip dysplasia.
Patient Instructions
- •There is no effective medical treatment to prevent progression of hereditary sensorimotor neuropathy (Charcot-Marie-Tooth disease).
- •Hereditary sensorimotor neuropathy types Ia and II are autosomal dominant and type Ix is X-linked dominant.
Considerations in Special Populations
- •Before skeletal maturity of the foot there is usually more flexibility.
- •A rigid foot with skeletal maturity is less likely to respond to nonoperative treatment for severe symptoms.
Suggested Readings
- Aktas S, Sussman MD: The radiological analysis of pes cavus deformity in Charcot Marie Tooth disease. J Pediatr Orthop B 2000; 9: pp. 137-140.
- Mosca VS: The cavus foot. J Pediatr Orthop 2001; 21: pp. 423-424.
- Olney B: Treatment of the cavus foot. Deformity in the pediatric patient with Charcot-Marie-Tooth. Foot Ankle Clin 2000; 5: pp. 305-315.
- Saifi GM, Szigeti K, Snipes GJ, et al.: Molecular mechanisms, diagnosis, and rational approaches to management of and therapy for Charcot-Marie-Tooth disease and related peripheral neuropathies. J Investig Med 2003; 51: pp. 261-283.
- Schwend RH, Drennan JC: Cavus foot deformity in children. J Am Acad Orthop Surg 2003; 11: pp. 201-211.