Conway McLean, DPM, Journal columnist

A reader writes: “I’ve had a bunion developing on my foot for a few years, but I don’t really have pain. I’ve heard different things about what can happen. Can mine cause problems even though it doesn’t particularly hurt?”

Dr. McLean explains: A bunion is a bump that appears gradually, usually over some years, on the inner side of the foot, at the base of the big toe. They can occur on both but may develop on only one foot. These are extremely common deformities in which the head of the first metatarsal bone moves slowly away from the other metatarsals towards the middle of the body. The big toe, in contrast, moves toward the other toes, crowding them over.

Bunions are a result of many factors, but foot function is the most important. Function follows form when it comes to the biomechanical workings of the leg, ankle, foot, and spine. This is why bunions are inherited, in that you may have foot architecture that encourages the development of this deformity.

Our reader likely had a relative with a bunion deformity, but so much goes into its growth, technically referred to as hallux valgus. Although a factor, the kind of activities one performs during their working years is a consideration, but not as important as many think.

The stresses to the first metatarsal are a vital part of this conversation, which are increased by an arch which rolls down too much (referred to as pronation). This altered positioning will also disturb the delicate balance of structures that keep the big toe in the proper position, leading to the leaning toe.

But to finally address your question, some of the consequences of this deformity are obvious, like pressure to the inner side of the foot from shoes. Over the years, a variety of changes result from this chronic and repetitive force. Callus may develop, which adds to the pressure on the skin and tissues beneath, potentially resulting in an ulcer with enough stress. Heart and blood vessel health are obviously a major issue in this discussion.

Sufferers of hallux valgus may first experience pain on the side of the second toe, not even technically part of the bunion. But the big toe is, indeed, bigger and can exert significant force on the neighboring digit. Repetitive pressure has many effects on skin, and many are not good, especially in the presence of vascular or neurologic incompetency (e.g. diabetic nerve problems and artery disease).

A painful corn can be produced by the skin on either of the adjacent surfaces of the first and second toe. These appendages are well innervated, meaning tremendous pain may be generated by that little digit. The agony resulting can alter your gait, how you walk, and that too comes with its own set of problems.

A reliable byproduct of this bony migration is altered joint motion. Any time a joint moves chronically out of position, there will be increased wear on the cartilage, with inflammation and bone spur formation also generally resulting. This latter issue leads to bone growth on the side of the head of the metatarsal bone, adding to the size of the prominence.

Much more subtle than these previous factors is the change in the supporting structure for the human body. One of the most important is the human foot, which primarily utilizes a tripod arrangement, with the heel bone, the outer metatarsals and the first. But in a typical bunion, the first metatarsal also moves up as well as out, serving to destabilize our musculoskeletal system’s foundation. Again, this may lead to an altered gait type, occurring each of those ten thousand steps a day, day after day, year after year.

Some common complications of a hallux valgus deformity are not so obviously connected to foot function. A change in the alignment of the knee and pelvis may arise from this ‘rolling down arch’ phenomenon, culminating in degenerative changes and chronic pain, usually in the knees or low back.

A topic this complex and this frequently seen can’t be adequately covered in this small space. It may be enough to know that roughly half of American women will develop some degree of bunion deformity during their lives, while a quarter of men are affected. Treatments attempted are numerous and sometimes comical, frequently based not on science but good marketing.

Our good reader has asked a frequently heard query: what are the consequences of a bunion if you don’t have obvious pain? As discussed, the complications are numerous and varied, occurring to some and not others. Plus, these complications are not often traced back to the source of the problem, the impaired functioning of the human anatomy, with its complex locomotor system and bipedal support. It’s called standing on your own two feet, something you don’t do as well if you have a bunion. (Part Two is next with a question about what to do!)