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Foot and ankle problems: I

In the first of two articles rheumatologist Dr Phillip Helliwell and colleagues look at common problems of the forefoot before giving tips on footwear advice

In the first of two articles rheumatologist Dr Phillip Helliwell and colleagues look at common problems of the forefoot before giving tips on footwear advice

The commonest problems encountered in primary care in the forefoot are: metatarsalgia – pain under the metatarsophalangeal joints, usually on weight bearing: Morton's neuroma; and Hallux valgus and bunions.

Much simple advice can be given but the conditions listed above cover a huge spectrum of disability and pathology. If simple measures fail then seek help from a podiatrist, physiotherapist or musculoskeletal doctor. Reliable internet-based advice and simple patient leaflets are also available.

Metatarsalgia

This common complaint may have several underlying causes but most commonly is idiopathic. Causes include:

• fat pad atrophy/displacement

• degenerative joint disease

• bursitis

• capsulitis/ plantar plate rupture

• neuroma

• stress fracture

• Freiberg's infraction

• inflammatory arthritis

Under normal circumstances there is a pad of fat underneath the metatarsophalangeal joints protecting this structure from undue pressure as the forefoot is used to push off during normal gait.

With disease, and age, this pad atrophies and can become displaced anteriorly leaving the underlying bone with only skin and subcutaneous fascia to protect it. An adventitious bursa may then form and become inflamed, or even infected if there has been a break in the skin.

Capsulitis and plantar plate rupture are not uncommonly seen in rheumatoid arthritis as the disease progresses. This leads to displacement of the fat pad and widening of the forefoot – common complaints are of ‘walking on pebbles' and an inability to find shoes wide enough to accommodate the forefoot.

High plantar pressures are often manifest by the formation of hard callus underneath the affected area so always inspect the sole of the foot for these.

Treatment of this problem is primarily support: replace the lost padding, footwear changes, cushioned insoles (see below) and functional insoles.

However, if conservative measures fail then a surgical solution should be considered. This may be a soft-tissue repair or may involve surgery to the underlying bony abnormalities. There are no studies on which appropriate advice on the timing and type of surgery can be based. Patients often find short-term relief from removal of the hard callus, either by using an abrasive material like pumice or by a podiatrist/chiropodist using a knife.

Morton's neuroma

Morton's neuroma is not a neuroma but perineural fibrosis. It is a form of entrapment neuropathy involving the common digital nerves of the lesser toes, usually the third and less often the second interspace.

Inter-digital neuromas are less common in the first and fourth web space. They occur most often in middle-aged women. The symptoms are burning and tingling down the interspace of the involved toes. The pain is usually made worse by walking. In some cases the pain will radiate to the toes or vague pains may radiate up the leg. Sometimes an audible and palpable click can be felt as the forefoot is gently squeezed – Mulder's click.

Treatment is both conservative and surgical. Forefoot offloading insoles (metatarsal insoles or pads) can be used to alleviate symptoms when weight bearing and are often all that is needed. If unsuccessful an injection of steroid into the interspace can be performed either ‘blind' (not recommended by those inexperienced in this technique) or ‘guided' with ultrasound.

In the latter case referral will usually have to be made to a GP with a special interest or a musculoskeletal radiologist.

A final solution is surgery. Two approaches are used. The first merely resects the transverse metatarsal ligament relieving the compression on the nerve. The second approach is to remove the affected nerve. This relieves the pain but leaves the patient with some numbness. If a plantar approach is used to remove the nerve the patient will have to spend three weeks off the affected foot.

Hallux valgus and bunions

Hallux valgus and associated conditions are probably the most prevalent forefoot condition in primary care. The most common presentation is with deformity of the great toe associated with pain at the first metatarso-phalangeal joint. There may be limited movement at the joint resulting in ‘hallux limitus' or ‘hallux rigidus'.

There is a strong genetic contribution to this problem and it may also be associated with Heberden's nodes in the fingers. Other important factors are mechanical – for example associated with an inherited short first metatarsal and pes planus – and environmental factors, such as footwear.

As the valgus deformity progresses an adventitious bursa may form over the prominent first metatarsal head (this is commonly known as a bunion) and this may become inflamed or even infected. Further displacement of the hallux pushes the second toe dorsally leaving a clawed second toe liable to ulceration as the toe joints rub on the overlying footwear.

Conservative measures meet with variable success. It is important to address the problem of footwear as narrow ‘court' shoes will only aggravate any inflamed bursa over the great toe. Other measures include:

• weight loss and low-impact exercise are of known benefit

• local therapies can be geared toward ameliorating abnormal mechanics or addressing the symptoms

– contoured foot orthoses reduce foot joint motions and offloading the forefoot

– footwear adaptations (rocker bottom shoes) limit the need for movement of degenerate joints while facilitating sagittal plane motion

– padding may reduce pressure over prominences

• intra-articular injection of steroid (not an easy or painless procedure) may provide symptom relief for up to eight weeks

Surgical intervention is usually definitive. There are a number of procedures available from bunionectomy and correcting the valgus deformity by osteotomy to surgical arthrodesis or excision arthroplasty.

When should a patient be referred for surgery? The general principle here is to refer after the failure of conservative measures. This point may rapidly be reached with some patients who seem particularly intolerant to orthoses and footwear adaptation and prefer the definitive solution.

However, although surgery is usually successful in the short term, complications such as infection can occur and there may be recurrence of deformity with time.

Footwear advice

Footwear is often the main cause of foot pain. A large proportion of the population wear badly-fitting footwear and subsequently report foot pain. It is considered the most problematic factor in managing foot pain and deformity for both the patient and the practitioner, especially because footwear is greatly influenced by environmental and personal factors.

The six requirements of ideal footwear in order to maintain good foot health – and accommodate orthoses when required – are:

• trainers or trainer-like shoes

• thick cushioning sole for shock absorption

• flat or small wedged heel for stability

• deep shoe with deep toe box to accommodate any forefoot deformity

• shoes with a fastening, for example lace-up, Velcro or buckle to ensure the shoes stay on

• ideally with a removable insole to allow more room for orthoses

Encouraging a patient to change their inappropriate style of footwear can often be difficult, although pain usually instigates a willingness to change by the patient. But if pain alone isn't enough to promote change the most effective approach is:

Assess patient fully before telling them how bad their footwear is

  • Identify the problem they are experiencing.
  • Inform the patient of the benefits of the treatment you are proposing
  • Highlight that their current footwear would reduce the treatment response or prevent treatment being introduced

When should the patient be referred for prescribed footwear?

• The patient, despite an improvement in their footwear style, reports increased foot pain and disability.

• The level of foot deformity increases.

• Patients are unable to purchase high street footwear that will accommodate their foot deformity.

• Recurrent footwear-related pressure-

induced lesions, such as dorsal toe region.

• To facilitate other treatments, such as the provision of foot orthoses.

‘Off-the-shelf' insoles (foot orthosis)

Modern foot orthoses come in a variety of forms. There is some evidence for a need to provide carefully customised orthoses in some disorders (such as rheumatoid arthritis), but there is a growing body of evidence for generic, ‘off-the-shelf' approaches to be used as a first-line approach for treating foot pain.

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Dr Philip Helliwell is senior lecturer in rheumatology at the University of Leeds.

Dr Anthony Redmond is lecturer in rheumatological podiatry, Heidi Davys is specialist rheumatology podiatrist and Ann-Maree Keenan is senior research fellow at the University of Leeds. Carl Ferguson (clinical lead), Lee Short and Brian Welsh are extended scope practitioners at Leeds PCT Musculoskeletal Reha

In part two the authors take a look at common problems of the heel and ankle

orthoses table

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