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bunion splaying of foot xray with arrows

The classic bunion is a bump on the side of the great toe joint. This bump represents an actual deviation of the 1st metatarsal. In addition, there is also deviation of the great toe toward the second toe. In severe cases, the great toe can either lie above or below the second toe.

What causes bunions? This question is often answered by blaming shoes. But in fact, shoes only play a small role in developing bunions. Yes, shoes, especially high heels cause abnormal squeezing of your forefoot. This in turn to help promote a bunion. But if everyone who wore high heels shoes had a bunion, there would be a lot more then the 15% prevalence we see in the general population. As you can see from the flow chart, genetics plays the major role in development of bunion deformities.

Genetics determines the way your foot functions. Are you flatfooted? Are your joints flexible or stiff? Do you have a high arch? Do you have tight muscles? These traits are determined by your genetic code. These characteristics then govern how your bones and joints move when you walk. As an example, if your joints are very flexible, this can cause an abnormal amount of instability in your forefoot when you walk. Over time, this abnormal motion will cause the a bunion to develop by allowing your first metatarsal to "drift" towards the mid-line of your body.

The fundamental driving force behind developing bunions as a result of faulty foot mechanics is genetics. Issues such as loose ligaments and flat feet, are inherited. The traits then act as the foundation for abnormal foot mechanics and lead to formation of bunions.

flow chart of how you why bunions happen

The most common symptoms associated with this condition are pain on the side of the foot just behind the great toe. A red painful bump is usually present. Pain is usually brought on with walking or sports. Shoes don't cause bunions but will typically aggravate them. Stiff leather shoes or shoes with a tapered toe box are the prime offenders. This is why bunion pain is most common in women whose shoes have a pointed toe box. The bunion site will often be slightly swollen and red from the constant rubbing and irritation of a shoe. Occasionally, corns can develop between the 1st and 2nd toe from the pressure the toes rubbing against each other.

xray of foot with normal angles

Normal bisection of metatarsal bones

xray of bunion showing abnormal angle

Red line: Abnormal bisection of first metatarsal

Green line: Correct bisection if bone where not splayed out

Treatment falls into two broad categories, conservative and surgical. From a conservative standpoint, efforts are directed at correcting faulty foot mechanics with custom molded insoles and relief of symptoms. These include:

The primary goal of bunion surgery is to relieve the pain associated with the deformity. This is accomplished by:

Bunion surgery procedures are based on many factors, including health, age and lifestyle of the patient. However, a critical factor in procedure choice is the grading of the bunion deformity.


Bunions are grade by the severity into three broad categories:

This is the term used to describe surgery which is performed exclusively around the great toe joint. There are several proximal procedures, including "Austin" or chevron procedure and "distal L" or Reverdin-Laird procedure. Indication for a proximal surgery include:

preop moderate bunion deformity Moderate bunion deformity
distal bunionectomy postop Example of moderate bunion surgery correction

via a distal bunionectomy

This is the term used to describe surgery which is performed in the around the big toe joint and in the middle part of the foot. Procedures we perform include Lapidus bunionectomy and crecentic bunionectomy. Indications include:

Details of a proximal bunion surgery:

severe bunion deformity xray X-ray of a moderate bunion deformity with hypermobility
postoperative lapidus bunion surgery Lapidus proximal bunion surgery


Dr. Richard Perez, DPM - San Antonio Podiatrist Foot Doctor
This content was authored by: Dr. Richard Perez

Dr. Perez is board certified by the American Board of Foot & Ankle Surgery and a Fellow of the American College of Foot and Ankle Surgeons. His clinical interest include sports injuries, aesthetic bunion surgery, heel pain and resident education.