Ankle Injuries

The ankle is a complex joint that is capable of a wide range of movement: flexion, extension, inversion and eversion as well as a combination of other movements. All this is necessary, not just for locomotion, but to traverse uneven ground. The ankle takes the full weight of the body and, in running and jumping, the forces that are exerted on it are considerable. The most common acute ankle injury is a lateral inversion sprain.

There are 2 joints that allow movement of the ankle:

• The true ankle joint (tibiotalar joint) - articulation is between the lower end of the tibia, the two malleoli and the body of the talus. This joint allows dorsiflexion and plantar flexion of the ankle.
• The subtalar joint - articulation is between the talus and calcaneus. This joint allows inversion and eversion of the ankle.

The distal tibia has a prominent medial malleolus and a less prominent posterior malleolus. The distal fibula is known as the lateral malleolus. The joint capsule and the surrounding ligaments stabilise the ankle. The distal fibula is joined to the distal tibia by the anterior and posterior inferior tibiofibular ligaments, an inferior transverse ligament, and a syndesmosis ligament.¹ The anterior and posterior talofibular ligaments join the fibula to the talus. The talus is joined to the calcaneus by the calcaneofibular ligament.¹ The deltoid ligament joins the medial malleolus to the talus, calcaneus, and navicular bones.¹

History and examination help to decide whether there has been a significant likelihood of an ankle fracture or foot fracture. Always apply and document the Ottawa rules:²

History

Ask about the following:

• How long ago was the injury?
• Mechanism of injury: injuries are most often whilst crossing uneven ground or after a sudden change of direction whilst playing sport. Was there excessive inversion or eversion? The injury may have resulted from jumping from a height.
• Was there any snap or popping sound? A snap may be a broken bone. A pop may be a ruptured ligament.
• Where exactly is the pain is felt?
• What happened afterwards? Was the patient able to weight bear immediately? Did they need help to walk? If it was a sports injury, were they able to continue?
• Previous ankle injury: is there underlying weakness or instability in the ankle? Could an old fracture be evident on X-ray?
• Past medical history: e.g. history of osteoporosis or metabolic bone disease.
• Drug history: e.g. long-term corticosteroid use that may increase the risk of osteoporosis.

Examination

Be sensitive to the patient's response and don't force any examination that is obviously causing distress. Examination of the uninjured ankle may give an indication of the normal range of movement and power.

• Inspection:
  • Did the patient walk in? If so, with how much discomfort and disability?
  • Look at the ankle. It there obvious deformity?
  • Is there swelling or bruising? Does any swelling or bruising look compatible with the mechanism of injury?
  • Is an effusion is present? This may be a fullness either side of achilles tendon.
  • Look for any open wounds.
• Palpation:
  • Palpate for crepitus and tenderness, especially over the malleolar regions, over the anterior tibiofibular ligament, the whole length of the fibula and the base of the 5th metatarsal. Does calcaneal pressure elicit pain?
• Test movement and muscle power:
  • Gently test all 6 different ranges of motion. These are:
    • Plantar flexion
    • Dorsiflexion
    • Inversion
    • Eversion
    • Inversion and eversion when plantar flexed
    • Inversion and eversion when dorsiflexed
  • The normal range of inversion is about twice the range of eversion.
  • Test muscle power by resisting these movements.
• Specific tests:
  • The anterior draw test: this can show excessive anterior displacement of the talus onto the tibia.³ If the anterior talofibular ligament is torn, the talus will subluxate anteriorly compared with the unaffected ankle.³ With the ankle in a neutral position, grip the tibia with one hand and cup the heel with the other, pulling the foot forward. A positive sign is a difference in movements in a relaxed patient between the injured and uninjured side, with the injured side having more movement than the uninjured.⁴
  • The cross-leg test: this can detect a high ankle sprain. Sit the patient in a chair. Ask them to cross their leg so that the lateral malleolus lies just laterally across the top of the knee. The test is positive if pressure applied to the medial aspect of the crossed knee produces pain in the syndesmosis area (see below).³
  • The side-to-side test for dorsiflexion injuries: this looks for widening of the ankle mortise. With the foot in a neutral position, hold the lower leg in one hand and heel in the other and stress from side to side. There may be pain or an audible clunk. This may also be called the inversion stress test or talar tilt test.³
  • The squeeze test: this involves squeezing the tibia and fibula together at mid calf. Pain is experienced more distally or in the ankle.
  • Thompson's test: this is to assess if the Achilles tendon is intact. With the patient lying prone with the knee flexed to 90°, squeeze the mid calf and this should should produce a visible plantar flexion at the ankle.
• Examine for neurovascular injury:
  • Assess the temperature of the foot.
  • Assess the capillary refill in the foot.
  • Palpate the posterior tibial artery and the dorsalis pedis artery (absent in 10-15% of the population).⁵
  • Test sensation in the foot/lower leg.
• Examine for co-existing injuries:
  • Pay special attention to the ipsilateral knee and foot.

Apply the Ottawa rules⁶ to see whether an X-ray is indicated.

A note about imaging

• If an X-ray is performed, anteroposterior, lateral and mortise views can be taken.^1,5 For the mortise view, the foot is rotated about 15° internally. This allows a better view of the ankle mortise.⁵
• If one injury is seen on X-ray, always look for a second.
• CT and MRI scanning are sometimes needed for fracture diagnosis and assessment of ligamentous or intra-articular injuries.⁵

This is based largely on the site of the pain and tenderness. There may be more than one injury.

• Lateral pain/tenderness: simple inversion sprain, fractured lateral malleolus, osteochondritis dissecans, peroneal tendon subluxation, Maisonneuve fracture, bifurcate ligament avulsion
• Medial pain/tenderness: eversion sprain, fractured medial malleolus, tendon injury (flexor hallucis longus or posterior tibialis)
• Anterior pain/tenderness: dorsiflexion sprain, anterior tibialis tendon injury, syndesmotic (high ankle) ligament sprain
• Posterior pain/tenderness: Achilles tendon injury, os trigonum fracture, posterior talus process fracture
• Sole of foot pain/tenderness: 5th metatarsal fracture

There is a separate article that discusses ankle fractures. Please refer to this.

• Simple sprains: lateral sprains are most common and can be treated conservatively. Simple medial sprains can also be treated conservatively, but tenderness over the deltoid ligament, with or without laxity, associated with fractures or instability may require fixation.
• Syndesmotic (high ankle) sprain: caused by dorsiflexion and eversion of the ankle with internal rotation of the tibia.³ The syndesmotic ligaments are the combination of the interosseus ligament and lower tibulofibular ligaments which normally stabilise the mortise joint and fix the fibula in the fibular notch. Look for widening of the mortise (tibia-fibula gap should be <5mm measured 1cm above the joint line on AP and Mortise views); stress X-rays may be needed. Squeeze test, side-to-side test and forced external rotation all cause pain at the syndesmosis. Healing takes longer than standard lateral sprains and may require internal fixation if there is associated fibular fracture.
• Fractured distal epiphysis of tibia: the Salter-Harris classification is normally used. Mild forms just need manipulation, more severe forms need open reduction and fixation.
• Fractured fifth metatarsal base: this is usually an avulsion fracture caused by sudden inversion. Conservative treatment is usually all that is required.
• Injury to posterior tubercle of talus or the nearby os trigonum: the os trigonum is an accessory ossicle located just posterior to the talus present in around 10% of people. Injury results from severe plantar flexion (e.g. in dancers, runners and footballers). It produces pain posterior to lateral malleolus, particularly on forced plantar flexion (eversion against resistance is pain free). Casting or steroid injection may help.
• Achilles tendon rupture: test continuity with Thompson test (described above). There is a separate article discussing Achilles Tendonitis and Rupture in more detail.

Ankle sprains are classified from grade I to grade III depending on their severity:¹¹

The management of ankle fractures is discussed in the separate article. 'PRICEMMM' is the mnemonic for treating ankle sprains:

• Protection is required with ankle bracing to prevent re-injury while the ligament heals. It may be provided by giving support with double Tubigrip™ when the patient is ambulant. It should not be worn at night. More substantial support, even casting, may be required. The value of double Tubigrip™ in ankle injuries has been disputed.¹² In one trial healing was no faster but the need for analgesia was actually increased. Bracing/semi-rigid supports in addition to elastic bandages may improve outcome.^13,14
• Rest is important at first, avoiding return to full activities too soon.
• Ice to decrease swelling and relieve pain, should not be applied directly to skin.
• Compression as soon as possible to decrease swelling (some dispute usefulness of compression see "protection" above).
• Elevation is the initial step for reducing swelling.
• Medication means NSAIDs or paracetamol for pain relief.
• Mobilisation should take place early on when pain free to expedite return to play. Return to mobility should be graded.
• Modalities are exercise and proprioception training to prevent re-injury

Most sprained ankles heal in a matter of days or weeks with no long term problems.

• Prevention of ankle sprains can be facilitated by wearing walking boots that protect the ankle rather than shoes when hiking over hills or uneven ground.
• Boots are often preferable for manual labourers as well.
• After injury, full rehabilitation to build up the muscles around the joint is important as weak muscles can predispose to further injury. Training builds muscle and improves proprioception.