Hallux Valgus

Synonyms: hallux abductovalgus, bunion.

The problem is lateral deviation of the great toe so as to put a valgus deformity on the first metatarso-phalangeal joint. A deviation of 15 to 20° is considered abnormal. This deviation upsets the biomechanics of the foot. It may cause subluxation of the first MTP joint and the great toe may even overlap the second toe.

Lateral subluxation produces a prominence on the metatarsal head (bunion) often followed by the development of a fluid filled bursa. This becomes painful as it rubs against the shoe.

It is helpful to consider this as correction of the biomechanical factors may prevent excessive pronation and progression of the deformity.When walking the hallux and digits stay parallel to the long axis of the foot. This is true generally regardless of how pronated or abducted the forefoot is. The pull of the conjoined adductor tendon, extensor hallucis longus, and flexor hallucis longus tendons ensures that the hallux and digits remain parallel. Displacement of the joint gives the tendons mechanical advantage and this displaces the joint further. As this occurs tension is created on the medial aspect of the joint (with compression laterally).
Medial tension causes ligaments to pull and cause the bone to proliferate on the dorsomedial aspect of the first metatarsal head. Lateral tension causes the sesamoid apparatus to stick in a dislocated position laterally. Remodelling occurs laterally and medially and this affects joint cartilage.

• Hallux valgus is common but incidence has not been accurately documented. Quoted figures differ not least because different authors have different definitions (for example the angle of deviation that is diagnostic or acceptable).
• It affects about 1% of adults in the United States.¹
• The incidence and prevalence is usually considered to be lower in children. A survey of 6000 children in Northamptonshire found the condition to be bilateral in 60 (1%) and unilateral in 36 (0.6%).²
• The prevalence and severity of the condition rises with age up to16% in those older than 60 years.¹

Because the risk factors affect both feet, the condition is usually bilateral although it may be more marked on one side than the other.

Risk factors

• Footwear affects incidence of hallux valgus and is lower in adults who do not wear shoes. However this does not mean that the footwear cause the condition. Tight shoes can cause pain and nerve entrapment in association with hallux valgus. Fashionable shoes can be too tight and too narrow to "flatter the foot". High heels force the foot down into the shoe and this further aggravates the problem. However It is worth noting that footwear problems are not limited to the dedicated followers of fashion. A study from Australia found that old people often wear tight and inappropriate footwear, especially old women.³
• There is higher incidence of hallux valgus in women. Footwear may account for this.
• Ballet dancers spend much time up on blocks, dancing on their toes, and so they may be expected to have a high prevalence of the condition, but this is apparently not so.⁴
• Age. Incidence increased with age, with rates of 3% in persons aged 15-30 years, 9% in persons aged 31-60 years, and 16% in those older than 60 years.¹
• Genetic factors have been cited with evidence to suggest familial tendencies.¹
• Associated diseases.

There are specific causes of biomechanical instability, including neuromuscular conditions. It may be associated with arthritis of various forms. These associated diseases include:

• Gout
• Rheumatoid arthritis
• Psoriatic arthropathy
• Joint hypermobility with conditions such as Ehlers-Danlos syndrome, Marfan's syndrome, Down's syndrome and ligamentous laxity
• Multiple sclerosis
• Charcot-Marie-Tooth disease
• Cerebral palsy

Presentation is usually as a result of pain, although the condition is also unsightly. Pain is usually progressive and may have been present for many years. The frequency or duration of pain may have recently started to increase, and activity may exacerbate the pain.

History

• A patient may present with a deep or sharp pain in the hallux MTP joint on walking, and exacerbation during particular activities. This suggests degeneration of the intra-articular cartilage.
• There may be an aching pain in the metatarsal head due to irritation by shoes. There may be a recent increase in the size of the deformity or medial bump.
• Ask about limitation of physical or daily living activities to understand the severity of the pain. Ask what relieves the pain. It may be simply removing shoes.
• There may be a history of trauma or inflammatory arthritis.
• A rarer presentation is burning pain or tingling in the dorsal aspect of the bunion, which indicates entrapment neuritis of the medial dorsal cutaneous nerve.
• The patient may also describe symptoms caused by the deformity, such as a painful overlapping 2^nd toe, interdigital keratosis, or ulceration to the medial metatarsal head, without complaint of the bunion deformity.

Examination

Examine the foot whilst bearing weight although much of the examination will have to be performed whilst not weight bearing.

Watch the patient walk. This will indicate the degree of pain and difficulty that the problem causes and abnormal gait may point to a contributory factor or be the result of the condition.

• Note the position of the hallux relative to the other toes. It may be overriding, under-riding or abutting the next toe. Distortion of the joint may occur in more than one plane.
• Note the medial prominence of the joint. Erythema or bursa indicates pressure from shoes and irritation.
• Note the range of movement of the hallux MTP joint. Normal dorsiflexion is 65 to 75° with plantar flexion less than 15°. Note if pain, crepitation, or both are present. Pain without crepitation suggests synovitis.
• Note any keratosis that suggests abnormal friction from abnormal gait.
• Associated deformities may include 2^nd digit hammertoes and flexible or rigid flatfoot. Instability of the 2^nd digit may allow a more rapid progression of hallux valgus, as it is unable to act as an adequate lateral buttress.
• With the patient standing note any:
  • Increase of hallux abduction in the transverse and frontal planes
  • Increase in medial prominence
  • Any change in dorsiflexion of the joint

Also note the general condition of skin and peripheral pulses. If surgery it to be contemplated it is imperative that peripheral blood flow is adequate for healing.

X-ray will show the degree of deformity and may indicate subluxation of the joint.

In an elderly patient in whom operation is considered, routine investigations are required to assess suitability for operation.

Some authors recognise 4 stages of severity,from excessive pronation, through worsening hallux abduction and culminating in dislocation of the joint. This can assist description and assessment, for example, when referring patients.¹

Drugs

Analgesics, including NSAIDs, may reduce pain and make the condition more bearable.

Steroid injection into the joint may give some relief of pain and inflammation.

Non-drug conservative treatment

There is no evidence of long term benefit from physiotherapy.

Orthotics may provide some relief by tending to correct some of the other associated deformities.

Surgery

The result of conservative management is so poor that surgery may be an attractive option. Surgery may be delayed without an adverse effect on the final outcome, although pain and patient satisfaction are improved with early operation.⁵

Indications for surgery

• A painful joint
• Deformity of the joint complex
• Pain or difficulty with footwear, inhibition of activity or lifestyle, and associated foot disorders that can be caused by this condition.

Associated foot disorders include:

• Neuritis or nerve entrapment
• Overlapping or underlapping adjacent toe
• Hammer toes
• Hallux metatarsocuneiform joint exostosis
• Sesamoiditis
• Ulceration
• Inflammatory conditions such as bursitis or tendinitis of the 1^st metatarsal head

Contraindications to surgery

• Peripheral vascular disease
• Active infection
• Active osteoarthropathy
• Septic arthritis
• Lack of pain or deformity
• Lack of compliance
• Age alone should not be seen as a contraindication but it is often associated with other significant medical conditions
• Other disease, especially of the cardiovascular or respiratory system that put the patient at risk during the procedure

Operative options

There are a large number of surgical options and the choice of procedure will depend upon the precise nature of the problem. It is usually a combination of bone and soft tissue surgery.

The simplest is the removal of the bony prominence (exostectomy). Alternatively, Keller's arthroplasty involves creating a flexible joint by excision of the medial eminence of the metatarsal head together with some of the proximal phalanx. Arthrodesis of the joint may be considered. Replacement of the joint for hallux valgus or hallux rigidus is a more recent option. NICE has given the procedure a cautious welcome.

Complications include delayed healing of the incision, osseous malunion or nonunion, nerve damage, haematoma, failure of a prosthesis, displacement of the osteotomy, delayed suture reaction, cellulitis, osteomyelitis, avascular necrosis, limitation of joint motion, hallux varus, and recurrence.

In addition to this are the risks associated with all surgery, especially if the patient is elderly. This includes venous thrombo-embolism.

The outlook is highly variable as is that of the patients who are treated. Hence there is a shortage of adequate trials to compare the outcomes of the various forms of treatment. A Cochrane review found very little good evidence on which to assess either conservative or operative treatments.⁶

Correction of the biomechanical factors may prevent excessive pronation and progression of the deformity. Judicious footwear may help prevent progression in some but not all cases.