By Dr Abbie Najjarine (podiatrist)

Figure 1: X-ray of a bunion

Having bunions – known in the podiatry world as Hallux Abducto Valgus – is very common and a condition I see almost every day in my clinics.  The question I am asked most is whether a patient’s shoes are the cause. Which is not a straightforward answer.

A patient’s biomechanics is usually the main factor for a bunion developing, but tight shoes can often aggravate a bunion during its development.

In addition, excessive pronation, where the foot turns inwards and downwards, will apply a strong force on the forefoot, increasing the load on the first metatarsal (bone beneath the big toe) to make it head in an abductory direction (outwards). This then allows 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 when the patient’s biomechanics is hereditary.

Overall 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. These stages are:

Figure 2: Secondary stage bunion

Figure 1: Primary stage bunion

  1. The first stage usually occurs from adolescents up to the age of 25 years. A primary stage bunion presents as a slight bump.
  2. The second stage often occurs between the ages of 25 and 55 years. Here the first metatarsal head adducts and the hallux abducts causing pressure on the second digit. Also 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” becomes tight and pulls the hallux further across in a bow like effect. Orthotic therapy is best at this stage.
  3. The third stage if the situation is not being controlled with orthotic therapy to prevent the condition from progressing further, the bunion will move into this stage. In this third stage of Hallux Abducto Valgus an overlapping of the hallux occurs either above or below the second digit and a patient’s shoes become hard to wear and it will also be hard to find shoes to accommodate the bunion as they will aggravate the first  MTPJ on the medial side (Thordarson, 2004).  At this point the condition is hard to treat and the patient will experience much pain. Patients may need to consult a podiatric or orthopaedic surgeon to correct the bunion deformity. After surgery the patient will probably need orthotics prescribed to treat any underlying biomechanical condition. Orthotics are essential to give the foot realignment and support, and prevent the reoccurrence of the Hallux Abducto Valgus or bunion.

Figure 3: Tertiary stage bunion

Treatment options

The main treatment to realign and control the pronation is orthotics. Here I would mould the custom made orthotic with the foot in the Neutral Calcaneal Stance Position (NCSP) then I would monitor the patient to ensure it is doing its job and controlling the pronation to prevent further bunion development.

Exercises to strengthen tendons (e.g. picking up objects with toes) will need to be done to support orthotic treatment.

Bunion strapping can be also done, however this is only applied at the first stages of bunion development.

It is important to explain to patients the causes of bunion development and the stages so that they understand why they must wear their orthotics and prevent the next stage developing..

Overall treating Hallux Abducto Valgus with orthotic therapy will realign the foot, limit calcaneal eversion, thus controlling pronation and taking pressure off the first MTPJ. It is important to monitor the bunion closely and review treatment if it worsens. It is important to ensure the orthotic is providing enough control and check the patient’s pronation.

If pronation continues it might be necessary to prescribe a firmer density orthotic to ensure correction and control is being achieved. If the patient presents with a short first metatarsal shaft the practitioner can create a Morton’s Extension to the orthotic. To do so place a Forefoot Orthotic Addition under the hallux or posteriorly to the distal digit of the hallux – this treatment is only successful in the first stage.

Refrences:

Najjarine A. R., (2008) The Orthotic Revloution, International College of Biomechanics
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