Differential diagnosis of common ankle injuries

Over 5,000 ankle sprains occur every day in the UK. Accurate diagnosis relies on a good history and identifying the location of the injury (see table).

Soft-tissue injury
Soft-tissue ankle injuries are usually the result of a twisted ankle. Previously treatment included immobilisation, but current evidence supports functional treatment.

Rehabilitation with rest, ice, compression and elevation (RICE) followed by physiotherapy is the gold standard.

In most cases, symptoms are reduced after six weeks but high ankle sprains involving the syndesmosis - the anterior tibiofibular, interosseous and posterior fibular ligaments - take longer to settle. Persistent symptoms beyond six weeks warrant further investigation.

Referral to a foot and ankle surgeon should be considered for patients with a history of a sprain with persistent pain.

Impingement
Inversion of the ankle can produce hypertrophy of synovium resulting in anterolateral impingement. Anteromedial impingement is commonly seen in football players. Posterior impingement is frequently seen in ballet dancers and football players.

In 10 per cent of the population, an ossicle (os trigonum) is present on the posterior aspect of the talus. Impingement, in these cases, results in inflammation of the synchondrosis, producing pain. These patients benefit from activity modification, steroid injection or occasionally arthroscopic surgery.

Achilles tendon injuries
Chronic Achilles tendinopathy causes a thickened tendon and activity-related pain. Treatment with eccentric stretching regimens is successful in 80 per cent of cases.

Steroid injection is not recommended because of an association with acute rupture. Acute posterior heel pain should be considered a sign of Achilles tendon rupture until proven otherwise. Operative repair gives the best results.

Tendinitis
Tibialis posterior tendinitis presents with pain and swelling at the posteromedial side of the ankle. The affected foot is often flatter than the other foot and rising on to tip-toes on the affected side is difficult.

Clinical diagnosis can be confirmed by MRI or ultrasound. Management includes rest, activity modification and physiotherapy. Technique correction is important for athletes and dancers. Resistant cases require surgery.

Flexor hallucis tendinitis is often associated with posterior impingement syndrome. Acute dislocation of peroneal tendons is rare. It presents with chronic subluxation. Conservative treatment is of little help.

Stress fractures
Stress fractures in the bones around the ankle joint may present with pain and swelling. They should be considered in a differential diagnosis of infection. An MRI may be needed for diagnosis. Treatment is immobilisation and analgesia.

Mr Mohan is an orthopaedic registrar and Mr Halliwell and Mr Solan consultant orthopaedic surgeons at the Royal Surrey County Hospital, Guildford