Bunions

Advising on footwear may be all that is needed in terms of treatment. From footwear to surgery, by GP Dr Louise Newson

Adducted metatarsal head (Photograph: SPL)
Adducted metatarsal head (Photograph: SPL)

A bunion is a hallux valgus deformity of the big toe. A deviation of 15-20 degs is considered abnormal. There is abduction from the midline, usually accompanied by rotation of the toenail to face the midline (valgus rotation).

This results in a prominent metatarsal head which is adducted towards the midline. Bunions are usually bilateral.

1. Aetiology and symptoms

Risk factors for developing bunions include female sex, wearing shoes that are too narrow, wearing high-heeled shoes, being overweight in men (obesity is actually protective in women),1 and in children, wearing footwear that is too tight. A longer first metatarsal correlates with more severe bunions.

However, there is insufficient evidence to support the common belief that unaccommodating shoes cause hallux deformity.2 In some patients' feet, there is a genetic predisposition for a non-linear osseous alignment and the development of hallux valgus.3

The most common symptoms are pain, limitations in activity levels and unwanted cosmetic appearance of the feet. The pain is usually progressive and has usually been present for many years.

2. Investigations

A bunion is obviously a clinical diagnosis. However, if surgery is to be considered, X-rays of the foot are usually taken. These may be taken at different angles, and when the patient is standing and also not weight-bearing.

However, there is no correlation between the severity of hallux valgus deformity measured by X-ray and the symptoms the patient may experience.

Other investigations are only necessary if other conditions, for example gout, rheumatoid arthritis or peripheral vascular disease, are suspected.

Patients' expectations and concerns need to be taken into account when assessing bunions, especially with regard to the need for surgical correction. For example, a young athletic patient is likely to be more concerned about the mobility of their joint than its physical appearance.

It is important to consider the type of shoes the patient has been wearing (and may continue to wear after treatment). One study found that most women who were questioned wore shoes narrower than their feet, shoes which were also shorter, narrower and had a smaller total area than those worn by men.4

The severity of bunions is sometimes classified as mild, moderate or severe (see table below).

Classifying Bunion Severity
Severity Hallux Valgus Angle Intermetatarsal Angle
 Mild  <30o  <10-15o
 Moderate  30-40o  10-15o
 Severe  >40o  15-20o

3. Treatment

Advising patients to wear shoes that have a rounded, enlarged toe area may help.

Most bunions can be treated without surgery. The main aim in early treatment is to relieve the pressure on the bunion, to stop progression of the joint deformity. Orthotic inserts are of limited benefit. Although they do not prevent progression of a bunion, they can be effective at easing foot pain.

If changing the footwear does not improve the pain, surgery may be an option, with numerous operations available to correct the deformity. Surgical options fall into several broad categories, including distal soft tissue reconstruction, distal and proximal osteotomies, arthrodesis of the metatarsophalangeal joint and the first tarsometatarsal, and resection of the bony prominence (exostectomy). Keller's arthroplasty involves creating a flexible joint by excision of the medial eminence of the metatarsal head, together with some of the proximal phalanx.

NICE guidance on minimal access techniques states that less invasive techniques may be attractive to patients, but need further evaluation.5

The most common complication after surgery is recurrence, particularly in cases where the deformity and soft tissues at the first metatarsophalangeal joint are undercorrected. Other complications can include stiffness, malunion, non-union and infection. Patients need realistic expectations after surgery.

  • Dr Newson is a GP in the West Midlands

Reflect on this article and add notes to your CPD Organiser on MIMS Learning

REFERENCES
1. Nguyen US, Hillstrom HJ, Li W et al. Osteoarthritis Cartilage 2010; 18(1): 41-6.

2. Easley ME, Trnka HJ. Foot Ankle Int 2007; 28(5): 654-9.

3. Perera AM, Mason L, Stephens MM. J Bone Joint Surg Am 2011; 93(17): 1650-61.

4. Thordarson D, Ebramzadeh E, Moorthy M et al. Foot Ankle Int 2005; 26(2): 122-7.

5. NICE. Surgical correction of hallux valgus using minimal access techniques. IPG332; February 2010.

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