Foot bunions are very common.

Many people believe that a bunion is a bump that ‘grows’ on the bone, and that during bunion correction it can simply be shaved off. Unfortunately, in most cases this is incorrect. Mostly the visible bump occurs because of the metatarsal bone tilting towards the centre line of the body, with the big toe tilting in the opposite direction, i.e. away from the midline. The visible bump is caused by the partially uncovered joint becoming prominent under the skin. In most cases this cannot simply be shaved off, because doing so would damage the joint.

Bunions are mostly not caused by genetics. Genetics can play a role, however modern shoes are the primary cause. There is a very elegant research study from Japan from the early 1980s (Kato and Watanabe 1981): prior to the introduction of Western shoes in the 1960s, most of the population wore platform sandals, and the incidence of bunions in the population was approximately 3% (the true genetic incidence). After the introduction of Western shoes with high heels and narrow toe boxes, the incidence of bunions quickly increased to over 30% in the same population.

Bunions develop when there is a muscle imbalance in the foot. The top picture of this blog post shows a tug-of-war between 2 groups of children. Each child represents a separate muscle, and the flag in the middle represents the big toe. Just as the flag moves in the direction of the stronger group of children, so the big toe moves towards the stronger or tighter muscles. Long-term use of narrow shoes will lead to stretching and weakening of the muscles on the one side of the big toe, so the toe moves.

Most bunions can be managed perfectly well with shoes that are wide enough (Aebischer and Duff 2020). It is important to understand that the front of the foot naturally widens with age, and shoe size should be measured and updated every 3 years. The 2 main solutions to a mismatch between the width of the foot and shoes, are to either (1) wear wider shoes, or (2) to have the shoes stretched in the area of tightness. 

Silicone toe spacers  and bunion splints don’t work (Tehraninasr and Forogh 2008).

If changing shoes is not your choice, then the only other way is to surgically reduce the width of the foot. However, there are some important considerations (Aebischer and Duff 2020).

• Cosmesis alone is not a sufficient indication for surgery. 

• Bunion surgery should not be offered to children or teenagers. 

• Surgery should not proceed in smokers, as the complications are higher.

There is no one-size-fits-all operation for bunions. Each bunion has its own personality, and the correct operation must be chosen. This means that even family members might need different operations. If the wrong operation is chosen, the toe can be worse off than before. It is important to consult with a surgeon who can choose the correct operation and perform it correctly. These are the minimum set of surgeries that any bunion surgeon must be able to perform well:

• rotational Lapidus fusion (this operation is mostly only performed by properly-trained foot & ankle experts)

• PROMO osteotomy (a new operation that is playing an increasing role in modern bunion surgery – I personally introduced this to the UAE in 2021).

• Scarf osteotomy

• Chevron osteotomy (including the biplanar variation)

• Akin osteotomy

• 1st MTP joint fusion

• proper lateral release of soft tissues

A final technical note is to touch on the recent increase in popularity of the “minimally invasive” surgery. The type of surgery chosen should be viewed as a “tool” used to correct the specific deformity of the patient. Minimal invasive surgery may have a role, however just like any other operative tool, there are also drawbacks. Some common problems with minimal invasive surgery include: significant shortening of the 1st metatarsal (with painful transfer of force of walking onto the 2nd and 3rd toes, and eventual hammer toes forming as a result), excessive removal of bone with the burr causing big problems if the bone does not heal, and unstable osteotomy with loosening of the surgical fixation (something to consider in areas where Vitamin D deficiency and/or osteoporosis is a problem). A new type of surgical complication is now being described, specific to minimally-invasive bunion surgery - this complicaton is termed "metatarsal explosion" (link here).

The goal of the operation is to place the 1st metatarsal head directly over the sesamoid bones, and in so doing restore the muscle balance evenly around the toe (please refer to the tug-of-war picture again). This is important to understand. Foot surgeons are “engineers of the foot”, and these goals are mechanical and measurable.

It is my observation that people with bunions often have little interest in the status of the muscle balance of the toe, but are rather more interested lifestyle goals, including (but not limited to):

• easy recovery (actually, the recovery time and restrictions will depend on the operation, which in turn is dictated by the deformity)

• expectation that the foot must never hurt again (it is important to note that most foot pain occurs in normal feet, as a result of lifestyle factors – therefore a foot can still hurt even after surgery if lifestyle factors are not addressed)

• the ability to wear any shoe (in research publications, up to 40% of patients still cannot wear tight shoes after surgery)

• to be better at running (running is sometimes a little worse after successful surgery – the slight stiffness from scarring of the soft tissues during healing can interfere with running)

• and to be happy with how it looks (which is very subjective – different people like different visual outcomes)

It is important to realise that the surgeon’s goals are mostly very different from the patient’s goals when it comes to bunion surgery. Surgeons have control over angles and position, but not direct control over any lifestyle-related goals. There is much room for disappointment in the difference between the two different goals. This is why it is important to always seriously consider trying non-operative treatment of bunions first, before considering surgery.

In summary, by going to an expert foot & ankle surgeon, you can be confident that the correct operation is being recommended, and will be performed well from a technical standpoint. However, surgery is no magic panacea. Always consider the surgical choices very carefully. The foot is the mechanical shock absorber of the body. Changing the shape of the foot can have unintended mechanical consequences. Surgery for cosmetic reasons alone is not recommended.

References

Aebischer, Andrea, and Samuel Duff. 2020. “Bunions: A review of management.” Aust J Gen Pract. 49, no. 11 (November): 720-723. DOI: 10.31128/AJGP-07-20-5541.

Kato, T., and S. Watanabe. 1981. “The etiology of hallux valgus in Japan.” Clin Orthop Relat Res. 157, no. 1981 (Jun): 78-81. https://doi.org/10.1097/00003086-198106000-00014.

Tehraninasr, Ali, and Hassan Forogh. 2008. “Effects of insole with toe-separator and night splint on patients with painful hallux valgus: a comparative study.” Prosthet Orthot Int. 32, no. 1 (March): 79-83. DOI: 10.1080/03093640701669074.