Causes of hallux valgus/bunion

Causes of a bunion

Hallux valgus is a common condition, especially in women. The big toe is so off-centred that it pushes the neighbour toes now being deformed into a ‘claw’-shape. How does hallux valgus start? What are the reasons for this deformity? With little explanation about its origins, you may be able to prevent its occurrence. Focus on what causes a hallux valgus

Hallux valgus still keeps a part of mystery about the causes of its emerging. But we know that some background elements create the possibility for the sidewards deviation of the big toe outwards and of the first metatarsal bone inwards. 


Causes of a bunion

Genetic predisposition

Studies show that hallux valgus is a family matter, repeated from one generation to the next(1). Compare with your mother’s feet! The genetical factor could be an excessive laxity of the body composition, or too severe expansions of tendon attachment(2,3). Extreme high joint flexibility combined with a deficit of muscle balance are supposed to facilitate the deviation of the metatarsus.


Foot shape

Another important genetical background is believed to cause hallux valgus : the shape of your feet. Three big categories can be distinguished:

  • Greek foot shape: the second toe is longer than the first (big toe);
  • Egyptian foot shape: the toes are ranged linear from the longest to the shortest one. In this case, the hallux (big toe) is the longest toe. This means an excessive length of the first section;
  • Square foot shape: the first (hallux ) and the second toe have the same length.


People having Egyptian foot shape seem to have higher probability to develop hallux valgus than those with Greek shape or square shape. As the first toe is longer than the others, it is more exposed to physiological stress, which increases its lever effect(4).


Anatomical deformity

Factors of anatomical nature play an important role in the emerging of hallux  valgus  . The flat foot-shape contributes to foot pronation (off-centring outwards) and to axial rotation of the first metatarsal bone. Progressively, it increases the length of the first section and the pronation of the big toe at the end of the walking movement.

The orientation as well as the anatomy of the spine of the joints between the first metatarsus and the first phalange can bring anatomical deviations and cause its deformity.

Another theory by Curvale and al., 1999(5), explains that when all predispositions for hallux valgus are present, the first phalange then operates like a pushing element. So it would create inwards (varus ) pression on the metatarsus and finally accentuate the process. Though this may not be the main reason, this adds to the other causes in charge of the deformity.

Local muscle increase could be another cause of hallux valgus . The abductor hallucis muscle is the only one providing opposition to the metatarsus varus (inwards). The strongest the deformity develops, the most the tendon of the abductor hallucis slips along the medial side of the first metatarsal head until it settles in this position. The deviation can continue without any physical opposition anymore as the abductor follows the modification of the tendon under the metatarsal head .


The effects of footwear

Not to forget the determining role of shoes in the progression of a bunion . Meant are slim, chiseltoe dress shoes with high heels. The foot is too tight embraced and is then slowly deformed in order to find some room in the pumps. Too tight shoes on the front contribute to increase the angle between the metatarsus and the first phalange, i.e. the hallux valgus !

This question of the choice of proper footwear is the main reason for hallux valgus relapsing, as it is not easy to change one’s everyday habits. Appropriate, comfortable footwear is the principal condition to prevent a recurrent bunion . Otherwise, the relapse is quasi-inevitable. 


The role of gender, weight and age

The studies by Nguyen and al.(6) on 600 patients in the USA point out that men and women show different causes of hallux valgus . According to its results, the choice of uncomfortable footwear combined with a low Body Mass Index (BMI) are determining factors in the occurrence of a bunion for women. At the opposite, high BMI and flat feet are contributing factors to a bunion for men.

However, it would be interesting to place this theory in confrontation with the fact that mostly women develop a bunion on the feet, the probability increasing with aging(7).



As you see, there are multiple causes for hallux valgus . If it is clear that one has no choice about its genetical and anatomical background, the choice of appropriate shoes belongs to you. Many footcare products are available to help preventing the occurrence of this foot deformity, like forefoot protective pads reducing strains and frictions on the feet.

Have a look at EPITACT®’s footcare solutions, your foot specialist: HERE !


Causes of a bunion


For more details about this general and simplified approach, here are further sources:

(1)Hannan MT, Menz HB, Jordan JM, Cupples LA, Cheng C-H, Hsu Y-H. High Heritability of Hallux Valgus and Lesser Toe Deformities in Adult Men and Women: Heritability of Hallux Valgus and Toe Deformities in Adults. Arthritis Care & Research. sept 2013; 65(9):1515‑21.

(2)Al-Saggaf S. Variations in the insertion of the extensor hallucis longus muscle. Folia Morphol (Warsz) 2003; 62:147–55.

(3)Gunal I, Sahinoglu K, Bergman RA. Anomalous tibialis posterior muscle as an etiologic factor in hallux valgus  . Clin Anat 1994;7:21–5.

(4)Lelièvre J., Pathologie du pied. Paris : Masson, 1961

(5)Curvale G, Rocheweger A, Piclet-Legre B. Hallux valgus  . Podologie. 1999; 27-080-A-30: p 6.

(6)Nguyen U-SDT, Hillstrom HJ, Li W, Dufour AB, Kiel DP, Procter-Gray E, et al. Factors associated with hallux valgus  in a population-based study of older women and men: the MOBILIZE Boston Study. Osteoarthritis and Cartilage. janv 2010; 18(1):416.

(7)Nix S, Smith M, Vicenzino B. Prevalence of hallux valgus  in the general population: a systematic review and meta-analysis. J Foot Ankle Res. déc 2010; 3(1):21.

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