By Dr Abbie Najjarine (podiatrist)

Figure 1: X-ray of a bunion

Hallux Abducto Valgus is a very common condition – one that I see almost every day in my clinics. Often I am asked if the shoes patients wear are the cause of the bunion?

The answer to this question is quite complex. The patient’s biomechanics is the main contributing factor behind the development of a bunion, however, tight fitting shoes can often aggravate the bunion during its development.

Excessive pronation will cause excessive forces to be applied to the forefoot, with increased load on the 1st metatarsal head in an adductory direction. This will allow rotation of the shaft and in turn the hallux (big toe) will compensate by abducting. A short first metatarsal or hyper

mobile feet are considerably more susceptible – in this situation, the patientís biomechanics is hereditary. A short first metatarsal is a major contributing factor as the first metatarsal adducts and drops to meet the ground. When combined with pronation this causes the hallux to abduct, hence the term “Hallux Abducto Valgus”. (Lorimer et al, 1997; Selner et al, 1992; De Valentine, 1992).

There are three stages of bunion development – orthotic therapy at each stage can prevent the bunion from progressing to the next stage.

Figure 2: Secondary stage bunion

Figure 1: Primary stage bunion

  1. Primary Stage: usually occurs from adolescents up to the age of 25 years. A primary stage bunion presents as a slight bump.
  2. Secondary Stage: occurs generally at between the ages of 25 and 55 years. The first metatarsal head adducts and the hallux abducts causing pressure on the 2nd digit. Callosity may develop on the medial side of the first Metatarso Phalangeal Joint (MTPJ) and medial hallux.  As the foot continues to pronate over several years the ground reaction forces the hallux into abduction and the extensor hallucis longus also becomes tight and pulls the hallux further across in a “bow” like effect.
  3. Tertiary Stage: If this situation is not controlled with orthotic therapy at the secondary stage to prevent the condition from progressing further, the bunion will eventually move into the Tertiary Stage (or the third stage). In the tertiary stage of Hallux Abducto Valgus an overlapping of the hallux occurs either above or below the second digit. As this takes place the patient’ís shoes become difficult to wear, and find it hard to find shoes to accommodate, as most shoes will aggravate the first MTPJ on the medial side (Thordarson, 2004).

Figure 3: Tertiary stage bunion

This stage is very difficult to treat, the patient may be in extreme pain and often find it hard to find footwear that can accommodate for the deviated hallux. Patients may need to consult an orthopedic surgeon to surgically correct the bunion deformity. Following surgery, the patient will need to have orthotic prescribed to treat the underlying biomechanical condition. Orthotics are essential to give the foot realignment and support, and prevent the recurrence of the Hallux Abducto Valgus (bunion).

Treatment

Prescribe an orthotic to realign and control the patient’s pronation. Heat and mould the orthotic with the foot in the Neutral Calcaneal Stance Position (NCSP). Following heat moulding, monitor the patient, ensuring the orthotic is adequately controlling the pronation, therfore preventing the further development of the bunion.

In addition to the orthotics the patient will need to do intrinsic foot strengthening exercises to strengthen the aponeurosis, e.g. picking up chopsticks with their toes.

Bunion strapping can be done, however it is only effective if the bunion is in the beginnings of stage one.

Figure 4: Adding a Mortons Extension to a heat moulded orthotic.

When treating hallux abducto valgus with orthotic therapy, it is important to explain not only the causes of bunion development but also the three stages. By doing so the patient will understand why they need to wear orthotics and that by doing so they will prevent the bunion from progressing to the next stage.

Treating Hallux Abducto Valgus with orthotic therapy will realign the foot, limit calcaneal eversion, thus controlling pronation and taking pressure off the first MTPJ. Monitor the bunion closely, and if it worsens or continues to be painful, review the prescribed orthotic – make sure the orthotic is providing enough control, and check if the patient is continuing to pronate through the orthotic.

If the patient is continuing to pronate it may be necessary to prescribe a firmer density orthotic to ensure correction and control is being achieved. If the patient presents with a short 1st metatarsal shaft the practitioner can create a Mortons Extension to the orthotic. To do so place a Forefoot Orthotic Addition under the hallux (attaching using double sided tape) or posteriorly to the distal digit of the hallux – this treatment is only successful in the first stage.

REFERENCES:

DE VALENTINE, S.J. (Ed) (1992) Foot and Ankle Disorders in Children, New York: Churchill Livingstone
LORIMER, D., FRENCH, GWEN, & WEST, S. (1997) Neales Common Foot Disorders: Diagnosis and Management, 5th Edition, Melbourne: Churchill Livingstone
SELNER, A. J., SENER, M.D., TUCKER, R.A., & EIRICH, G. (1992) Tricorrectional Bunionectomy for Surgical Repair of Juvenile Hallux Valgus, JAPMA
THORDARSON , DAVID B. (2004) Foot & Ankle, Lippincott Williams & Wilkins