The key things to establish in taking a history from a patient with pes cavus are:
- what actual problems does the patient have?
- what level of disability (if any)?
- is there an identifiable neurological cause?
- is the problem progressive?
- are there any high-risk features, such as
- a history of neuropathic ulceration or infection
- serious systemic effects such as respiratory problems or cardiomyopathy?
What is the problem?
It is vital to establish each individual patient’s symptoms and to identify their concerns. Many patients have quite limited problems and little or no disability, and so can be helped with quite simple interventions.
- Toe deformity with rubbing on shoes, often over flexed PIP joints or at the tips of claw toes
- Metatarsalgia due to forefoot plantar flexion and fixed toe deformity
- Lateral foot pain (increased lateral weight bearing) and painful calluses on the lateral foot border due to hindfoot varus
- Ankle instability due to hindfoot varus and peroneus brevis weakness
- Shoewear/ fitting difficulty due to deformity
- Difficulty walking, which may be due to foot deformity, foot drop or proximal weakness
- Generalised pain - Cooke surveyed the UK CMT Society and found that 50% of patients with CMT had generalised nonspecific foot pain wich did not respond to sugical correction of defomities
- Worries about progression or inheritance rather than personal symptoms - many of these are better handled by referral to a neurologist or clinical geneticist
Is there a neurological cause?
Cavus is generally thought of as a neurological deformity due to muscle imbalance. However, not all patients have an identifiable neurological cause. Important questions include:
- is there a family history of neurological disease (often worth asking the patient if they have heard of eg Charcot-Marie-Tooth disease), or of foot deformity? Always ask the patient if they have been given a neurological diagnosis - even in exams they will often tell you!
- are there any other neurological problems, such as general weakness, difficulty with fine motor functions such as writing, or problems with vision
- is the deformity progressive or static? This may open up the patient's main concerns - some patients simply wish reassurance regarding their disease and likelihood of progression and may have very little functional impairment despite apparent, severe deformity.
- is there a spinal problem, such as scoliosis or skin abnormalities on the spine?
- are there other limb abnormalities? The commonest manifestation of diastomatomyelia in the series of Miller (1993) was limb asymmetry.
Also, always ask whether the patient has had skin breakdown on the foot, especially skin breaks they were not initially aware of. Loss of protective sensation can make a big difference to treatment plans and the risks of treatment.