Bunions can get pretty ugly — and not just because they look funny. But because with the big toe angled so oddly, the foot loses the normal function of that joint and changes how a person walks. They can also be very painful.
What is a bunion anyway? That bony knob sticking out from the big toe is caused by a change in the alignment of the first metatarsal and the hallux. The first metatarsal is the bone inside the big toe. The hallux is the bone in your foot that connects to the first metatarsal. The joint where these two bones meet is called the first metatarsophalangeal joint or MTP joint.
As the hallux shifts away from the foot (a movement called abduction), the first metatarsal adducts (moves toward the other toes). The result is a disruption of the metatarsophalangeal (MTP) joint. Swelling around the joint develops and forms the deformity you see on the outside of the foot that’s called a bunion. Once the shift begins, it seems there’s no stopping it without surgery.
No one knows exactly why this shift gets started. There have been many theories and experts agree that it’s probably multifactorial. In other words, there are many things combined together to cause this foot deformity. Some of those things include environment (shoe wear), genetics (family history), and anatomy.
It’s possible that the use of a shoe insert called an orthotic to support the arch early on may prevent this unsightly deformity. At least that’s what a group of physical therapists at the University of Minnesota Medical School are proposing. If that’s true, it will be the first treatment discovered to affect bunions in any way other than surgery. And that would be good news for bunion sufferers!
This group of therapists took a look at the arch of the foot and suggested that a flattening of the arch may be at fault. If you look at the alignment of the foot arch from the front of the foot, it’s easy to see how a change in the tilt of the arch can change pressure placed on the big toe. Collapse of the arch while standing up on the foot in a weight-bearing (load) position may set up a chain of events that ultimately leads to hallux valgus (the medical term for bunions).
The shape of the arch of the foot affects the axis of the first metatarsal (big toe). As the arch drops down, the first metatarsal axis becomes more vertical (aligned up and down). Shifting of the hallux and first metatarsal occur and that affects the joint axis, too. Pressure on and stretching of the ligaments and cartilage around the joint further weaken the support of the bony structures.
With the right kind of support, the metatarsal axis can be oriented more toward the horizontal (straight across from side to side). In this way, the arch can help support the weight of the body without collapsing, shifting the arch, and altering the alignment of the foot. A shift in one arch affects joint axis, bones, ligaments, alignment, and so on.