Bunions

What are bunions?

'Bunions' or hallux valgus is a condition that affects the bones and joints associated with the big toe. It is one of the most common deformities of the forefoot. The condition usually develops slowly and results from the gradual dislocation of the joint, normally because of instability during gait (the way in which an individual walks).

There is a gradual displacement of the first metatarsal bone toward the mid-line of the body, and a simultaneous displacement of the big toe away from the mid-line toward the smaller toes. This causes a prominence of bone on the inside (medial) margin of the forefoot; this is termed a bunion.

As the deformity progresses, the big toe will shift toward the outside of the foot. In severe cases, the big toe will actually overlap or underlap the second toe. Due to shoe irritation the bones within the big toe joint may actually become thicker and a protective fluid filled sack called a bursa, may form.

Bunions are often hereditary in nature, but are also associated with diseases such as rheumatoid arthritis. The incidence of bunions is much higher in women than men. This was thought to be caused  purely by shoe fashion; however over recent decades genetic factors and certain other predisposing abnormalities of foot function have been implicated in bunion development.

The role of genetics in bunion development has been emphasised by studies that show that the rates of bunions within cultures that do not wear shoes are the same as cultures that wear shoes. However wearing narrow toed and high heeled shoes can greatly accelerate the formation of a bunion.

Orthotics are medical devices that are worn inside the shoes and are prescribed by a Podiatrist after a careful assessment. Orthotics can slow or halt the progression of bunions by addressing the instability which causes the deformity, often providing complete symptomatic relief. However orthotics cannot reduce the pre-existing bony deformity.

When a bunion becomes problematic (through either making shoe fitting difficult, or increased pain) surgery may be performed to correct the deformity. Following bunion surgery, foot orthotics should be worn to prevent the faulty foot mechanics that caused the bunion; otherwise bunion recurrence is likely.

Symptoms

• Redness, swelling, or pain along the inside margin of the foot just behind the big toe
• Moderate to severe discomfort at the site of the bunion when wearing shoes, particularly if tight fitting.
• A painful callus may develop over the bunion.
• There may be a painful corn on the adjacent sides of the first and second toes.
• There may be irritation caused by overlapping of the first and second toes.
• There may be stiffness and discomfort in the joint between the big toe and the first metatarsal.
• There may be a fluid-filled cyst or bursa between the skin and the "bunion bone".
• Skin over the bunion may break down, causing an ulceration which can become infected.
  

Causes

• Abnormality in foot function, particularly a pronated foot. This is probably the most important and common causative factor.
• Family history of bunions.
• Narrow-toed dress shoes and high heels may contribute to the formation of a bunion.
• Rheumatoid and Psoriatic arthritis.
• Genetic and neuromuscular disease (eg. Down's, Ehler-Danlos and Marfan's syndromes) resulting in muscle imbalance.
• Limb length inequality can cause a bunion on the longer limb.
• Generalized laxity of the ligaments.
• Trauma to or surgery on the soft tissue structures around the great toe (first metatarsal-phalangeal) joint.

What You Can Do

• Apply a commercial bunion pad around the bony prominence, use only non-medicated pads.
• Wear shoes with a wide and deep toe box. You should be able to "dimple" the leather over your bunion.
• Avoid all high heeled shoes.
• If your bunion becomes painful, red and swollen, try elevating your foot and applying ice for about 20 minuets every hour.
• If symptoms persist, consult a Podiatrist.
• Use a prefabricated pronation control orthotic such as the Orthosport Activ-8 ™ orthotic, a perfect choice for moderate over pronators.
   

What the Podiatrist May Do

• Prescribe functional orthotics to correct faulty foot function, and help prevent worsening of the deformity.
• Apply special pads and dressings to protect the bunion from shoe pressure.
• Inject steroid and local anaesthetic around the bunion to reduce inflammation. This is especially useful if there is an associated bursitis ( a fluid-filled cyst or sack between the skin and the "bunion bone").
• Apply various splints or digital orthotics to reposition the great toe joint.
• Recommend commercially available or custom-made shoes.
• Recommend bunion surgery to correct the deformity.
   

Other Causes Of Pain At The Big Toe Joint

• Arthritis in the first metatarsal-phalangeal joint
• Injury to the soft tissue structures around the first metatarsal-phalangeal joint.
• Fracture of the great toe or first metatarsal.
• Tight shoes may cause pain in an otherwise normal joint.
• Sesamoiditis-an inflammation of one or both small bones which rest in tendons under the first metatarsal-phalangeal joint.

X-rays of bunions

This x-ray illustrates a severe bunion deformity.

• The first metatarsal has deviated towards the mid-line of the body, resulting in a prominence of the first metatarsal head on the inside border of the foot. This is what is known as a bunion.
• There is a marked deviation of the big toe toward the lesser toes. The big toe is now resting under the second toe.
• There is bone formation along the inside border of the first metatarsal head. This is a protective bursa, formed as the result of repeated shoe pressure.
• The bones resting between the first and second metatarsals are called sesamoid bones. They normally rest in small tendons beneath the first metatarsal head. As the bones displace with the formation of a bunion, these come to lie in the interspace.
• The second toe has contracted termed a 'hammer toe'.