See separate article on ankle fractures.

Ankle injuries are common in primary care, A&E and sports medicine.¹

Anatomy of the ankle joint^1,2

There are two 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. The anterior and posterior talofibular ligaments join the fibula to the talus. The talus is joined to the calcaneus by the calcaneofibular ligament. The deltoid ligament joins the medial malleolus to the talus, calcaneus, and navicular bones.

Assessment of ankle injuries

History and examination help to decide whether there has been a significant likelihood of an ankle fracture or foot fracture. Apply and document the Ottawa Rules.³

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.
• The patient may report a 'snap' sound, but this does not differentiate between a sprain and a fracture.¹
• Where exactly is the pain 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^1,4

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. Is there obvious deformity?
  • Is there swelling or bruising? Does any swelling or bruising look compatible with the mechanism of injury?
  • Is an effusion present? This may be a fullness either side of the 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?
• Examine for neurovascular injury:
  • Assessment of neurovascular status is by sensation over the dorsal and plantar surfaces of the foot, measuring capillary refill in all digits, and palpating the distal pulses (the dorsalis pedis artery is absent in 2-3% of the population). Vascular compromise is the urgent concern in dislocations and fracture-dislocations. Sural nerve and peroneal nerve palsies are a rare complication of severe sprains.²
• Movement/power:
  • These cannot be tested in most cases as the joint may be swollen, painful, fractured or dislocated.
• Examine for co-existing injuries:
  • Pay special attention to the ipsilateral knee and foot.
  • Check for tenderness (fracture) of the proximal fibula.
• Specific tests (if appropriate) include:
  • 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 posterior calf muscles - this should produce a visible plantar flexion at the ankle if the tendon is intact.
  • The anterior drawer test: this can show excessive anterior displacement of the talus on to the tibia. If the anterior talofibular ligament is torn, the talus will subluxate anteriorly compared with the unaffected ankle. With the ankle in a neutral position, stabilise the leg over the distal tibia with one hand and cup the heel with the other, pulling the foot forward. The patient should be relaxed and both legs compared. A positive sign is a greater anterior movement on the injured side, with the injured side having more movement than the uninjured.
  • The talar tilt test (also called the inversion stress test): this stresses the calcaneofibular ligament. This test is not usually feasible in acute injuries, owing to swelling, but may be used to assess stability during healing. With the foot in a neutral position, hold the lower leg in one hand and the heel in the other: invert the ankle. Compare with the other leg.
  • Tests for syndesmosis injury:
    • Squeeze test: involves squeezing the tibia and fibula together at the mid calf. If pain is experienced more distally or in the ankle, this is a positive test.
    • Interosseous membrane tenderness test: this also looks for syndesmosis injury. Position the patient supine. Palpate between the tibia and fibular from the ankle proximally. Note the length of tenderness.
    • External rotation stress test: externally rotate and then passively dorsiflex the ankle. Pain at the syndesmosis is a positive test.

Investigations

Ottawa Rules³

Clinically it may be very difficult to differentiate a fracture from a severe sprain without an X-ray unless there is obvious distortion or instability. The Ottawa Rules were introduced in 1992 to reduce the number of unnecessary X-rays, whilst at the same time minimising the number of fractures missed. They are not perfect but they have been validated and, if a clinician applies the Ottawa Rules, this is effective risk management using a respected protocol. The Ottawa Rules also appear to be applicable to children.⁵

Imaging

• If an X-ray is performed, anteroposterior (AP), lateral and mortise views can be taken.^6,7 For the mortise view, the foot is rotated about 15° internally. This allows a better view of the ankle mortise.⁷
• 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.⁷

Differential diagnosis²

Commonly missed fractures are:¹

• Proximal fibula.
• Base of 5th metatarsal.
• Talus - dome, lateral process (Snowboarder's fracture) or posterior process.
• Tibial plafond.

Other causes of acute ankle pain are:

• Achilles tendon injury or Achilles tendonitis.
• Joint pathology, e.g. gout, osteochondritis dissecans.
• Tendon injury, e.g. flexor hallucis longus, posterior tibialis or anterior tibialis tendon injuries; peroneal tendon subluxation.
• Stress fractures.
• Anterior process fracture of the calcaneus.

Initial management of ankle injury

1. As with any trauma patient, carry out a primary survey following the 'ABCDE' principles of resuscitation and trauma care.
2. Assess clinically for obvious deformity and for neurovascular status.
   

   Note: if there is neurovascular compromise or dislocation (obvious deformity) of the joint, the fracture should be reduced immediately - before X-ray - under analgesia or sedation. Displaced fractures should be reduced as soon as possible after initial assessment - this reduces pain/swelling and may prevent skin necrosis.

3. Fractures and dislocations: see separate article Ankle Fractures for further management.

Ankle sprains - classification and management^1,4

Classification²

These are common injuries. Ankle sprains are classified from grade I to grade III depending on their severity:

• Grade 1 injuries - the ligament is stretched, with microscopic (but not macroscopic) tearing. Swelling is mild, with little or no functional loss and no joint instability. The patient bears weight at least partially.
• Grade 2 injuries - the ligament is stretched with partial tearing. Swelling is moderate-to-severe, with ecchymosis.There is moderate functional loss and mild-to-moderate joint instability. Patients usually have difficulty bearing weight.
• Grade 3 injuries - the ligament is completely ruptured. Swelling is immediate and severe, with ecchymosis. The patient usually cannot bear weight (or not without severe pain). There is moderate-to-severe instability of the joint.

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.

Treatment involves:⁸

• Protection, Rest, Ice, Compression and Elevation (PRICE).⁹
  • 'Protection' options are: Tubigrip®, elastic wrap or ankle tape, or a brace.^10,11
• Avoid Heat, Alcohol, Running (or other exercise), and Massage (HARM) in the first 72 hours after the injury.
• Analgesia if required.
• Do not immobilise the joint. Begin flexibility (range of motion) exercises as soon as they can be tolerated without excessive pain.

Severe sprains

A short period of immobilisation in a below-knee cast or pneumatic brace may speed recovery compared to a compression bandage alone.^12,13 In one large study, the use of either an Aircast® brace or a below-knee cast hastened recovery, but did not affect the long-term outcome.¹⁴

Syndesmotic (high ankle) sprain

• This is caused by dorsiflexion and eversion of the ankle with internal rotation of the tibia, e.g. during skiing or football. The syndesmotic ligaments are the combination of the interosseous ligament and lower tibiofibular ligaments which normally stabilise the mortise joint and fix the fibula in the fibular notch.
• Look for widening of the mortise (tibiofibular gap should be <5 mm measured 1 cm 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 - consider the diagnosis in those with continuing pain >6 weeks after the original injury.
• Treatment may involve a fracture boot, short leg cast or non-weight bearing. Internal fixation may be required if the joint is unstable (see separate Ankle Fractures article).

Rehabilitation after ankle sprain

• After injury, full rehabilitation to build up the muscles around the joint is important; weak muscles can predispose to further injury.^1,4
• Supervised exercises may provide some benefit for recovery.¹⁵
• Athletes with severe sprains may need an ankle orthosis for several months following the injury.¹
• Chronic ankle instability may follow an acute lateral ankle sprain. Initial treatment involves bracing or neuromuscular training. However, if symptoms persist, surgery may be considered.¹⁶

Prevention

Prevention of ankle sprains may be facilitated by wearing walking boots that protect the ankle (rather than shoes) when hiking over hills or uneven ground, or for manual labour.

Document references

1. Slimmon D, Brukner P; Sports ankle injuries - assessment and management. Aust Fam Physician. 2010 Jan-Feb;39(1-2):18-22. [abstract]
2. Young CC et al, Ankle sprain, Medscape, Sep 2011
3. Ottawa Ankle Rules; Ankle Injury - X-ray for acute injury of the ankle and foot. Guidelines and Protocols Advisory Committee, British Columbia, January 2009.
4. Small K; Ankle sprains and fractures in adults. Orthop Nurs. 2009 Nov-Dec;28(6):314-20. [abstract]
5. Plint AC, Bulloch B, Osmond MH, et al; Validation of the Ottawa Ankle Rules in children with ankle injuries.; Acad Emerg Med. 1999 Oct;6(10):1005-9. [abstract]
6. Mulligan ME, Imaging in Ankle Fractures, Medscape, May 2011
7. Iskyan K et al, Ankle Fracture in Emergency Medicine, Medscape, Feb 2010
8. Crocco A; Review: the Ottawa Ankle Rules are accurate for excluding fractures in acute Evid Based Med. 2009 Dec;14(6):184.
9. Sprains and strains, Prodigy (July 2008)
10. Kerkhoffs GM, Struijs PA, Marti RK, et al; Different functional treatment strategies for acute lateral ankle ligament injuries in adults. Cochrane Database Syst Rev. 2002;(3):CD002938. [abstract]
11. Kemler E, van de Port I, Backx F, et al; A systematic review on the treatment of acute ankle sprain: brace versus other Sports Med. 2011 Mar 1;41(3):185-97. doi: 10.2165/11584370-000000000-00000. [abstract]
12. Seah R, Mani-Babu S; Managing ankle sprains in primary care: what is best practice? A systematic Br Med Bull. 2011;97:105-35. Epub 2010 Aug 14. [abstract]
13. Lamb SE, Marsh JL, Hutton JL, et al; Mechanical supports for acute, severe ankle sprain: a pragmatic, multicentre, Lancet. 2009 Feb 14;373(9663):575-81. [abstract]
14. Cooke MW, Marsh JL, Clark M, et al; Treatment of severe ankle sprain: a pragmatic randomised controlled trial Health Technol Assess. 2009 Feb;13(13):iii, ix-x, 1-121. [abstract]
15. van Rijn RM, van Ochten J, Luijsterburg PA, et al; Effectiveness of additional supervised exercises compared with conventional BMJ. 2010 Oct 26;341:c5688. doi: 10.1136/bmj.c5688. [abstract]
16. de Vries JS, Krips R, Sierevelt IN, et al; Interventions for treating chronic ankle instability. Cochrane Database Syst Rev. 2011 Aug 10;(8):CD004124. [abstract]

Internet and further reading

• Reeves DA et al, Ankle taping and bracing, Medscape, Oct 2011
• Lin CW, Hiller CE, de Bie RA; Evidence-based treatment for ankle injuries: a clinical perspective. J Man Manip Ther. 2010 Mar;18(1):22-8. [abstract]
• Ivins D; Acute ankle sprain: an update. Am Fam Physician. 2006 Nov 15;74(10):1714-20. [abstract]