Genetics also play a role in developing bunions
Ruth L. Thomas, MD
Derived from the Greek word for turnip, bunions are a significant problem in modern society. Most clinicians recognize bunions from the bump on the side of the great toe joint. When the bump is associated with lateral deviation of the toe, the deformity is called hallux valgus. Hallux valgus is the most common pathologic entity affecting the great toe, occurring in 2 percent to 4 percent of the population.
Hallux valgus deformity occurs at least twice as often in females as males. In multiple series reporting on surgical correction of juvenile hallux valgus deformity, 84 percent to 100 percent of the patients were girls. This preponderance continues through adulthood.
Shoes, heredity to blame
Although it is unclear why females have a predilection for bunion deformity, shoes have been cited as the primary extrinsic factor contributing to the development of hallux valgus deformity. According to the literature, incidences of hallux valgus deformity have been reported as high as 48 percent in shoe-wearing females, compared to 16 percent to 33 percent in shoe-wearing males and 2 percent in barefoot populations. Interestingly, even in barefoot populations, hallux valgus deformity is more common in females than in males.
The primary intrinsic factor in the development of hallux valgus deformity is genetic predisposition. A familial history of bunions, the frequency of bilateral involvement, and the strong preponderance of bunions in females (although up to one third of men also have hallux valgus) all support a genetic etiology. In a 1951 study, 77 percent of hallux valgus patients reported that their mothers also had bunion deformities. In a review of 60 juvenile hallux valgus cases, maternal transmission of the disorder was noted in 72 percent, with variable penetrance of the trait.
Managing the pain
Although many bunions do not hurt and never require surgical intervention, some patients with hallux valgus deformity seek medical attention for significant foot pain.
The first step in managing bunion pain is to eliminate pressure caused by shoes. For most patients, this means wearing flat or low-heeled shoes made of soft stretchable leather with a wider toe box. It is important that the toe box not have decorative stitching or seams over the area of the bunion because this prevents the upper part of the shoe from adapting to accommodate the deformity.
Relieving pressure over the irritated bump is often the only intervention needed to control bunion pain. Women may benefit from wearing shoes that are wide enough to accommodate the bunion and still fit snuggly on the heel. These are known as “combination-last” shoes and are usually available at shoe stores. Females with bunions should also consider purchasing athletic shoes in the men’s department.
When surgery is warranted
Females are nine times more likely than males to need corrective bunion surgery, yet surgical intervention should only be considered when conservative measures have failed. The type of surgical procedure chosen is determined by the severity of the hallux valgus deformity, specifically, by the degree of hallux valgus angulation, the degree of intermetatarsal angulation, and the degree of pronation of the great toe.
Typically, hallux valgus angulation—the angle formed between the great toe and the first metatarsal—is less than 15 degrees. Severe deformity exists when the hallux valgus angulation is greater than 40 degrees.
Intermetatarsal angulation is the angulation between the first and second metatarsals. Normally, this is 9 degrees or less; anything greater than 15 degrees is considered moderate to severe hallux valgus deformity.
The third component of hallux valgus deformity is the degree of pronation of the great toe. Normally, the toenail of the great toe should face the ceiling. With hallux valgus deformity, the nail will often pronate or roll downward with the nail facing the opposite foot.
Mild hallux valgus deformities can be corrected with a procedure to the great toe joint itself. Severe deformities will require an osteotomy of the first metatarsal to reduce the intermetatarsal angle or a fusion of the joint between the first metatarsal and the midtarsal bone. Residual pronation often requires adding another osteotomy to the great toe to allow it to be rotated to a neutral position. For patients with severe bunion deformities, a period of nonweightbearing for 6 weeks postoperatively may be recommended.
The corrective option chosen by the surgeon should be the procedure that has resulted in the best results in the past; however, the result of bunion surgery is never perfect. Lateral deviation deformity will recur in up to 10 percent of patients. Decreased motion of the great toe joint is also common after surgery. A few patients will have a tender scar or the great toe will no longer touch the ground. With any osteotomy or fusion procedure, the risk of nonunion or malunion is present. This may require prolonged immobilization or even another surgery to reduce pain or improve function.
Despite these complications, most patients are generally pleased with the results of hallux valgus surgery. Still, multiple possible complications can occur; only patients with pain should be considered as surgical candidates.
To summarize, hallux valgus deformity occurs much more frequently in females than in males. Although the constriction of women’s shoes has been implicated as a major causative factor in the development of hallux valgus in females, clear evidence for maternal genetic transmission of the deformity exists. Although hallux valgus deformity may develop in some females, no matter what type of footwear they choose, due to a genetic propensity, it may not develop in others until they have subjected their feet to narrow constrictive shoes for many years.
Ruth L. Thomas, MD, is a member of the AAOS Women’s Health Issues Advisory Board, professor of orthopaedics, and director of Center for Foot and Ankle Surgery at the University of Arkansas for Medical Sciences. She can be reached at email@example.com
Putting sex in your orthopaedic practice
This quarterly column from the AAOS Women’s Health Issues Advisory Board and the Ruth Jackson Orthopaedic Society provides important information for your practice about issues related to sex (determined by our chromosomes) and gender (how we present ourselves as male or female, which can be influenced by environment, families and peers, and social institutions). It is our mission to promote the philosophy that male and female patients experience and react to musculoskeletal conditions differently; when it comes to patient care, surgeons should not have a one-size-fits-all mentality.
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June 2012 Issue
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