Bunions (Hallus Abducto Valgus) are a common foot problem that affects the joint at the base of the big toe (first metatarsophalangeal joint). In Latin “bunion” means enlargement, while “hallux abducto valgus (HAV)” refers to a bending inwards of the big toe as seen on the image. As you see, the big toe bends in towards the other toes while the bone behind it (1st metatarsal) pushes outward. This creates a considerable amount of stress on the joint (first metatarsophalangeal joint). Due to this bending inwards, a sharp angle at the big toe joint is created, resulting in the formation of a bunion. Initially, this enlargement is composed of swollen tissue which becomes irritated by any external pressure (for example tight shoes). Eventually this swollen tissue thickens to form a very large lump or bunion.

There is an obvious relationship between bunions and shoes, since bunions do not occur in cultures that go barefoot. High heels, pointed shoes, ballet shoes, excessively tight shoes, and even cowboy boots often lead to the development of bunions.

 Anatomy and Biomechanics

From a biomechanical perspective, bunion formation creates a cycle of dysfunction. As the bone behind the big toe (1st metatarsal bone) moves outwards, the inner arch of the foot becomes unstable and starts to collapse. This instability, or lack of support in the arch, increases stress on the angle at the point where the bunion is forming. This stress accelerates the formation of the bunion, which in turn further destabilizes the arch of the foot. To truly deal with this problem, you must address both the foot instability and joint angle.

In addition to the stresses caused by poor shoes, simply walking with your feet in a “turned out” position can also lead to bunion formation from the stress it puts on two particular muscles, the adductor hallicus and the abductor hallicus.

The adductor hallicus is an interesting muscle which is shaped like the number seven. The adductor hallicus transverses from several of the lateral toes into your big toe. When the adductor hallicus contracts, it pulls the big toe towards the 2nd toe. When the adductor hallicus muscle becomes tight and restricted, it continually pulls the big toe towards the second toe (even without contracting). The adductor hallicus tends to become restricted in individuals who excessively pronate or walk with their feet turned outwards (a huge percentage of runners and dancers).

This pulling action of the adductor hallicus disrupts a key balance in muscle tension, which normally keeps the big toe in a neutral or straight position. This balance occurs between the adductor hallicus and the abductor hallicus muscles. The abductor hallucis normally resists the pulling action of the adductor hallicus. The abductor hallucis runs from your heel (calcaneus) to your big toe (proximal phalanx). Constant pulling from the adductor hallicus weakens and overstretches the abductor hallucis. Without the appropriate counter-balancing action of the abductor hallucis, the big toe moves inward, and bunion formation accelerates.

Treatment

The objective of non-surgical treatment is to prevent the progression of the bunion by correcting the biomechanical stress on the foot, by realigning the joint as much as possible, and by increasing the intrinsic strength of the foot. We achieve this by using soft-tissue tissue techniques such as Active Release Techniques to break adhesions that form in the adductor hallicus muscle or other affected structures. We use taping help bring the big toe back into a neutral position. We have our patients perform a series of strengthening, stretching, and self-myofascial release exercises. The selection of exercises will vary greatly between different patients, and is dependant on which areas of their kinetic chain has been affected.

If you would like more information, or would like help with your bunions then just give us a call at 403-241-3772