Bunion

A bunion, medically referred to as hallux valgus or hallux abducto valgus, is a deformity of the metatarsophalangeal (MTP) joint that connects the big toe to the foot. This condition is characterised by a lateral deviation of the big toe, leading to a red, prominent, and painful joint at the base of the big toe. The onset of bunions is typically gradual, and complications may include bursitis or arthritis.

Signs and Symptoms

The primary symptoms of a bunion include irritation of the skin around the affected joint, and blisters may form more easily at the site. Pain is often exacerbated when walking. Bunions can complicate finding properly fitting footwear, often necessitating a larger shoe size to accommodate the increased width of the foot. In severe cases, foot pain can occur even without the constriction of shoes, indicating a mechanical function problem of the forefoot.

Cause

The exact cause of bunions remains unclear, although several factors have been proposed. These include wearing overly tight or high-heeled shoes, family history, and rheumatoid arthritis. The American College of Foot and Ankle Surgeons notes that while footwear can exacerbate the condition, genetics play a fundamental role. Excessive pronation of the foot is another contributing factor, as it increases pressure on the inside of the big toe, leading to the deformation of the medial capsular structures of the joint.

Pathophysiology

The bump associated with a bunion is partly due to a swollen bursal sac or a bony anomaly at the MTP joint. The larger part of the bump originates from the head of the first metatarsal bone, which has tilted sideways. Bunions often involve a deviation of the big toe towards the second toe and an increased angle between the first and second metatarsal bones. Over time, the small sesamoid bones beneath the first metatarsal may also become deviated. Osteoarthritis, reduced range of motion, and discomfort can accompany bunion development. Inflamed bursal sacs (bursitis) can be particularly painful.

Diagnosis

Bunions are usually diagnosed based on symptoms and confirmed with X-rays. The X-ray should be taken with weight on the foot to measure the hallux valgus angle (HVA), which is considered abnormal if greater than 15–18°. The severity of hallux valgus can be graded based on the HVA and the intermetatarsal angle (IMA). An IMA greater than 9° is considered abnormal.

Treatment

Conservative treatments for bunions include wearing proper shoes, using orthotics, and taking nonsteroidal anti-inflammatory drugs (NSAIDs). Though these measures alleviate symptoms, they do not correct the deformity. Severe or persistent discomfort may necessitate surgical intervention by an orthopaedic or podiatric surgeon.

Orthotics

Orthotics such as toe spacers, valgus splints, and bunion shields can reduce pain but are not proven to correct the physical deformity. A variety of orthotic devices are available, including off-the-shelf products and custom-moulded orthotics.

Surgery

Surgical procedures aim to correct various pathologies associated with bunions. These procedures can involve removing the abnormal bony enlargement, realigning bones, straightening the big toe, and addressing arthritic changes. Factors such as the patient's age, health, lifestyle, and activity level influence the choice of procedure.

Traditional bunion surgery can be performed under local, spinal, or general anaesthesia. Recovery typically takes 6 to 8 weeks, with crutches often required for mobility. Modern procedures use more stable forms of fixation, such as absorbable pins, reducing the need for orthopaedic casts. However, some patients may experience long-term stiffness, limited range of motion, or scarring.

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Self-assessment MCQs (single best answer)

What is the medical term for a bunion?

Which joint is affected by a bunion?

Which of the following is NOT a proposed factor in the development of bunions?

Which angle is considered abnormal in the diagnosis of hallux valgus based on X-rays?

Which symptom is NOT typically associated with bunions?

What conservative treatment is used to alleviate bunion symptoms but does not correct the deformity?

What kind of imaging is used to confirm the diagnosis of a bunion?

Which of the following is a surgical procedure specifically mentioned for treating bunions?

What is a common recovery time following traditional bunion surgery?

Which of the following is a possible long-term complication after bunion surgery?