Careful examination is important in evaluating pes cavus, write Dr Emma Lackey and Mr Ron Sutton.
Pes cavus describes high longitudinal arches that do not flatten with weight-bearing. There may be associated claw toes. Other features can include plantar fascia contracture, and a rolling out of the ankle where the heel tilts inward.
Some cases of pes cavus are idiopathic and may be familiar, but it is important to consider whether there is an underlying pathology. Some are congenital, and others result from trauma such as fracture malunions or burns.
It is important to rule out an underlying neuromuscular or neurological condition, such as muscular dystrophies, Charcot-Marie-Tooth disease, poliomyelitis, syringomyelia, spina bifida, diastematomyelia, Friedreich’s ataxia, hereditary motor sensory neuropathy, and cerebral palsy. Spinal tumours should be considered in all new cases of unilateral pes cavus without a history of injury.
Identifying an underlying condition helps to determine if the condition is progressive and to plan management.
Symptoms vary depending on the severity of the condition. The deformity often causes increased weight-bearing on the metatarsal heads, resulting in localised pain and callus formation. The reduced area of contact with the floor also gives lateral pain.
Other symptoms include difficulty with shoe fitting, foot fatigue, reduced mobility, stiffness and ankle instability leading to frequent sprains. There may be other symptoms relating to an underlying neurological or muscular problem.
In evaluating pes cavus, careful history and examination are important. The analysis should include an assessment of the foot, noting the presence of claw toes, callosities and whether the abnormality is flexible or rigid. The range of motion at the ankle, midfoot and forefoot should be determined.
Careful spinal and neurological examination should include a review of gait and sensation that may reveal a neurological problem. Examination of shoes may show increased lateral wear.
Pes cavus is evaluated in detail with weight-bearing foot and ankle X-rays. An MRI can determine if there is any underlying pathology such as suspected spinal cord abnormalities, and spinal X-rays should be considered in spina bifida.
Expert neurological advice is appropriate, especially when an abnormality has developed in previously healthy feet. Investigations such as muscle biopsies, EMG and nerve conduction studies should be arranged if indicated.
Treatment can be conservative or surgical. Traditional options include careful shoe selection and padding to dis- tribute weight from bony prominences to relieve pressure. Physiotherapy may help stretch tight muscles and strengthen weak muscles. If sensation is impaired, frequent skin inspection is required to check for ulceration.
Surgery is not necessary in all cases and does not produce a natural foot. The aim is to relieve pain and provide a plantigrade, flexible but stable foot.
Surgical options include plantar fascia release, tendon transfers, osteotomies and sometimes arthrodeses. Claw toes may also require correction. No single operation is suitable for all and frequently repeated surgical procedures may be necessary, especially in progressive deformities.
Surgery is contraindicated if vascularity is poor or cannot be improved. Ideally, soft tissues around the ankle and foot should be intact without excess swelling, ulceration or infection.
Surgical complications include non-union, malunion, under- and over-correction, recurrence or progression of deformity, infection, nerve injury, and continued pain.
– Dr Lackey is a GP and Mr Sutton a consultant orthopaedic surgeon in Northumberland
KEY POINTS ON PAS CAVUS
– Pes cavus is a high-arched foot which does not correct on weight-bearing.
– It is important to consider an underlying neurological or neuromuscular problem.
– Spinal tumours should be seen in cases of new onset of unilateral pes cavus without a history of injury.
– Conservative treatment may be all that is required, but if surgery is needed the goal is to relieve pain and produce a stable and flexible plantigrade foot.