Hallux Valgus (Bunion Deformity)

Hallux Valgus (Bunion Deformity)

‘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.

Figure 1 & 2
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.

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.
Cause
• 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
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 Doctor.

There are only two ways to treat a bunion. Either change the size and shape of the shoe or change the size and shape of the foot.Once a bunion gets to be irritating or painful and shoe wear is uncomfortable, surgery may be recommended.
Depending on the severity of the deformity, this osteotomy can be done either at the end of the metatarsal (a distal osteotomy) or if the deformity is more severe, the osteotomy is performed at the base of the first metatarsal (a proximal osteotomy).
One of the more common distal metatarsal osteotomies that is performed is called the chevron osteotomy.

Figure 3&4
An operation which I use frequently is called the chevron osteotomy. It is a V-shaped bone cut made in the metatarsal. Once the V-cut in the metatarsal is made, the bone is shifted over and the remaining edge of the bone is shaved down as shown here.

Figure 5

These are before and after pictures of a 17 year old female with a painful bunion (hallux valgus) corrected with a chevron osteotomy.