One of the most notable features of a bunion is an apparent enlargement of the bone at the base of the big toe on the inside of the foot. Describing a bunion as only an abnormal bone growth though would not be a complete or accurate explanation of the problem.
The medical term for the common bunion is hallux valgus. Hallux refers to the big toe. Valgus is a term that means outward angle. A bunion occurs when the position of the bones in the big toe shift in a manner that causes it to point in the direction of the other toes. This displacement causes the end of the first metatarsal bone to appear more prominent on the inside of the foot. This subjects the joint to increased irritation that then leads to inflammation and swelling of the surrounding tissue. Prolonged irritation causes additional bone to start forming at the joint. Over time this will make the bunion appear larger.
Bunion Formation
The exact cause of bunions in unknown. There is controversy regarding the effects genetics and shoe wear have on the condition. Hallux valgus is reportedly rare in populations that habitually go barefoot. Heredity certainly appears to play a role in the formation of bunions, particularly in younger individuals. The other suspected causative factors can be grouped into 4 categories:
- Biomechanical problems such as excessive pronation or hypermobile joints
- Systemic or neuromuscular diseases included rheumatoid arthritis, cerebral palsy, and connective tissue disorders
- Traumatic injuries such as a nonunion fracture or dislocation of the joint
- Pre-existing structural abnormalities
Bunions and Footwear
My personal feeling is that choice of footwear plays a major role in the development of the problem and is not simply an irritating factor. Here is a photograph from a study by an orthopedist named Dr. Phil Hoffman back in 1905, comparing the foot of an adult that had never worn shoes (B) to a child who had worn shoes for only a few months (A).
Notice the position of the big toe with the rest of the foot. Previous studies have shown shoes affect the development of the arch, so it makes sense that shoes would play a role in hallux valgus. In 1912, not long after the Hoffman study, Edward Lyman Munson wrote a book called The Soldiers Foot and The Military Shoe. The book was intended as a guide to the Army for providing soldiers with footwear that would allow them to march effectively and without injury. The book has many insightful points about improper footwear and I’m surprised it didn’t have a larger impact on shoe design in the years after its publication. Here is a picture from the book comparing an x-rays taken of a foot both with and without a shoe.
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Given that both of the works cited above are over 100 years old, it’s clear that the issue of the effect shoes can have on foot health have been known and discussed for a while. It seems logical that shoes could be a direct cause of bunions either by:
- having a narrow toe box that forces that bones of the toes together or
- indirectly encouraging excessive pronation or flattening of the arch which would then put additional pressure on the big toe
References
- Robinson D, Hasharoni A, Halperin N, Yayon A, Nevo Z. Mesenchymal cells and growth factors in bunions. Foot Ankle Int. 1999 Nov;20(11):727-32.
- Hoffman, P. Conclusion drawn from a comparative study of the feet of barefooted and shoe-wearing peoples. J Bone Joint Surg Am. 1905;s2-3:105-136.
- Banks A, McGlamry E. McGlamry’s comprehensive textbook of foot and ankle surgery. 3 rd ed. Philadelphia: Lippincott Williams and Wilkins; 2001.
- Nix S, Vicenzino B, Collins N, Smith M. Characteristics of foot structure and footwear associated with hallux valgus: a systematicreview. Osteoarthritis Cartilage. 2012 Oct;20(10):1059-74. Epub 2012 Jul 5.
- Munson, E. The soldiers foot and the military shoe. Fort Levenworth: George Banta Publishing Co; 1912.
