Hallux Valgus (Bunions)

Introduction

Bunions are typically thought of as just a bump on the side of the foot near the big toe. Technically this part of a bunion is only one aspect of the larger affliction of the condition known as 'hallux' (big toe) 'valgus' (deviated away from the body). The condition actually goes deeper and reflect a change in the anatomy of the foot. Self-care includes using bunion pads and wearing roomy shoes.

Figure 1. Typical abnormalities in a case of bunions. Note that the term bunion only refers to one aspect of the deformity

Physiology

It is likely that bunions result from an imbalance of the forces around a big toe due to inherited as well as environmental influences. Bunions happen over time. What begins as the big toe pointing toward the second toe ends up as changes in the actual alignment of the bones in the foot. At the core of it the adductor hallucis pulls the toe at an angle allowing the long flexors of the toe to pull the big toe. In time the head of the metatarsal protrudes and becomes scarred in this position. Although the skin might be red, a bunion therefore actually reflects a change in the anatomy of the foot. There is also a condition called tailor’s bunion or bunionette. This type of bump differs from a bunion in terms of the location. A tailor’s bunion is found near the base of the little toe on the outside of the foot.

Figure 2. At the core of the changes in hallux valgus, the small muscles of the foot cause a tightness on the outside of the big toe joint. This results in muscle imbalances that increase the deformity further.

Anyone can get bunions, but they are more common in women. People with flat feet are also more likely to get bunions because of the changes in the foot caused by bunions. There is also a condition called adolescent bunion, which tends to occur in 10 to 15-year old girls. In general, these cases are considered physiological and it is best to support these them with orthotics until maturity whereupon surgical intervention may need to be performed for problematic cases.

Bunions may be hereditary, as they often run in families. This suggests that people may inherit a faulty foot shape. In addition, footwear that does not fit properly may cause bunions. Bunions are made worse by shoes that are tight, fit poorly, or are too small. Bunions may also be caused by inflammatory conditions such as arthritis.

Common reasons for surgical correction

Many people do not experience symptoms in the early stages of bunion formation. Symptoms are often most noticeable when the bunion gets worse and with certain types of footwear. These include shoes that crowd the toes and/or high-heeled shoes. By en large most cases are treated with splints and orthotic footwear.

When symptoms do occur, they may include:

1. Physical discomfort or pain

2. A burning feeling

3. Redness and swelling

4. Possible numbness

5. Difficulty walking

Surgical intervention

A number of procedures have been described for bunion correction. We have over 20 years experience in correction of these deformities and generally favour the illustrated techniques below. Nevertheless the basic goals are a metatarsal osteotomy, realignment, bunionectomy, lateral capsular tightening, medial capsular and adductor hallucis release.

Figure 3. Bunion correction surgery involves a metatarsal osteotomy (in this case a chevron osteotomy is illustrated), bunionectomy, lateral soft tissue release (adductor hallucis and joint capsule) and a medial reefing (tightening).

Figure 4. Close-up view of a chevron osteotomy and the fixation required to maintain stability (representative picture from different patients). Occasionally when hardware retention is undesirable, pins may be used but require more prolonged nursing in a cast.

Outcomes

In general surgical outcomes are good. While in the past recurrences were common with soft tissue only procedures, more recently results have been better through the use of bony corrective procedures. In general, over correction is not desirable and should be avoided.

Figure 5. Typical correction achievable using current techniques. Overcorrection should be avoided beyond the the dashed line shown as this would result in the opposite condition (hallux varus)

Special considerations

A commonly associated condition is the hypermobile first ray. This is common in adolescents and may be physiological. If however this persists into adulthood the foot becomes flat restricting weight bearing activity. A fusion of the first ray is therefore to be recommended. In addition, due to crowding of the toes the remaining toes may become clawed or curly and may need to be addressed. We generally prefer to do this at a second procedure as spontaneous corrections do occur after the hallux valgus is corrected.

Figure 6. In the Lapidus procedure a further fusion of the metatarso-cuneiform joint is done as the first ray is loose. This is common in adolescent flat foot and is therefore only operated on in adulthood if it is a cause of persistent pain.

Post-operative care

The patient is placed in a forefoot cast for 6 weeks and is able to ambulate on the heels. Subsequently, general weight bearing on the forefoot is permitted with good bony union. Jogging may be permitted at 3 months from surgery.