Bunions are probably the most common foot disorder seen in podiatry. The term bunion itself is used by patients describing the bony lump found near the base of the big toe, which is usually an adaptation of the positional change of the big toe. Hallux abducto valgus (HAV) is a medical term, which describes the position of the hallux (big toe) with respect to the connecting bone of the mid foot (metatarsal). In this foot disorder, the hallux deviates towards the lesser toes and the metatarsal moves towards the midline.
There are many reasons why this deformity occurs such as:
- Hereditary factors
- Footwear habits
- Foot type
- Biomechanical factors (pronation)
- Neuromuscular dysfunction
- Ligament Dysfunction (laxity)
The most common causative factor is inheriting a foot type from your family that is prone to bunions. Feet that are subjected to pronation also have a higher incidence of attaining HAV deformities. This is a problem that has many causes and more than one may be occurring at the same time.
With the positional change of the hallux, pain is a common occurrence. As the foot goes through the gait cycle the hallux plays an integral role as the body’s weight transmits through during propulsion. With this in mind, it easy to see how the change in the hallux joints (metatarsal phalangeal joint and the proximal interphalangeal) would cause joint narrowing and early degeneration of the articular cartilage. In addition, two small bones (ossicles) found underneath just behind the joint will start placing extra pressure on the metatarsal. Along with bony changes, there are many soft tissue changes as the hallux and metatarsal reposition, which causes added strain to other bony structures and can accelerate the problem.
Like in many other conditions, it is important to understand what is causing the abnormality, and at what level the degeneration has reached. HAV has four significant stages which may take many years to progress from one stage to another and each stage gives an indication to what level of degeneration is present. A good history of the problem is required, along with establishing what may be causing HAV and be possibly accelerating it. Depending on the stage of the deformity, it is imperative to determine the degree of mobility available to the patient with such a deformity.
There are two ways to treat this pathological foot conditions, conservatively and surgically. Conservative treatment is the first line treatment which consists of splints and orthotic care to reduce the causative factors. Realigning the foot with the aid of an orthotic helps prevent further degeneration and/or reduce symptoms of HAV in any stage of its deformity. Along with orthotic care, patients may require debridement of corns and calluses produced due to extra forces produced on the foot. Orthotics will also help the function of the big toe joint as it allows it to bend in the correct position.
Footwear advice is also essential in the conservative care of bunions / HAV, there may be a need to change footwear, so it is able to fit properly and be compliment with orthotics. Surgical correction of bunions / HAV is available, however should only be considered when conservative care has failed to reduce the onset of bunions / HAV. It is only considered if there is a clear sign that it will induce a better quality of life for the patient.