Information
Editors
Ankle Fractures
Essentials
- The physician should be able to differentiate between stable and unstable ankle fractures and plan the treatment accordingly.
Definitions
- In this text, the term ankle fracture refers to fractures of the malleolus (also high fibular fractures) caused by a twisting motion.
- Three malleolar sites: lateral, medial and the posterior triangle (avulsion fracture of the posterior tibiofibular [TFP] ligament)
- Stable ankle fractures are fractures of the malleolus where the talus has not dislocated from the tibial articular surface.
Anatomy
- The weight of the body is transmitted to the talus, which wedges tightly into the ankle mortise situated between the medial and lateral malleoli.
- Syndesmosis ligaments: the anterior (TFA) and posterior (TFP) tibiofibular ligaments, the syndesmosis ligament, the interosseous membrane
- The most important structure in the prevention of external rotation of the talus is the deep portion of the deltoid ligament
- Lateral collateral ligaments prevent the inversion of the ankle.
Classification and mechanism of injury
- Weber classification
- A. Transverse fracture of the lateral malleolus below the talocrural joint (rare)
- The mechanism of injury involves supination of the foot (ankle inversion).
- Small ligament avulsion fracture on the tip of the malleolus associated with ligament injuries of the ankle is not a Weber type A fracture as such; iinstead, it is treated like a ligament injury of the ankle.
- B. Spiral fracture of the lateral malleolus, which begins at the ankle joint and travels upwards towards the posterior aspect (the most common type: 70-80%)
- Supination of the foot and external rotation of the talus
- C. High fibular fracture (15-20%): fracture of the fibula, which starts above the ankle joint
- Pronation of the foot (ankle abduction) and usually external rotation of the talus
- Types A, B and C are further divided into subcategories according to the extent of medial involvement.
Diagnosis
Clinical diagnosis
- Clarify the mechanism of injury
- Twisting of the ankle, for example when slipping
- The patient is not always able to give an exact account of the mechanism of injury.
- Visual inspection
- Is the ankle dislocated? Deformity
- Swelling and haematomas and their location
- Palpation
- Is there tenderness both on the lateral and medial sides?
- Testing the stability: does the talus stay within the ankle mortise?
- Palpate the entire lower leg in order to locate all areas of tenderness.
- Remember the possibility of high fibular fracture and syndesmosis injury.
- A syndesmosis injury may occur without a simultaneous fracture.
Radiological diagnosis
- Indications for radiography: see Ottawa ankle rules Ottawa Ankle Rules in the Prediction of Ankle and Foot Fractures Ankle Sprain
- If an ankle fracture is suspected, a mortise projection and a lateral projection will almost always suffice.
- The entire lower leg should be x-rayed if a high fibular fracture is suspected clinically.
- A mortise projection is taken with the foot in 10-15 degrees of internal rotation in order to obtain a true anteroposterior view of the ankle mortise.
- In a normal ankle, the articular surfaces of the tibia and the talus are parallel to each other.
- In a mortise projection, the radiological joint space is equally wide between the tibia and the talus and between the lateral malleolus and the talus.
- The width of the syndesmosis is dependent on the projection (difficult to estimate from plain x-rays).
Stability assessment
- If instability is suspected, the patient should be referred to a health care facility where the stability can be tested using fluoroscopy.
- In a Weber A fracture, the ankle fork is practically always stable.
- Weber B fractures of the lateral malleolus
- Findings suggesting an unstable fracture
- Pain, swelling and haematoma formation on the medial side of the ankle (injury to the deep portion of the deltoid ligament)
- The talus shows pathological posterolateral movement during stability testing.
- The fracture of the lateral malleolus associated with marked dislocation
- An x-ray shows joint incongruence.
- Tilting of the articular surface of the talus in relation to the articular surface of the tibia (talar tilt)
- Posterolateral displacement of the talus (talar shift)
- Medial joint space > 5 mm is clearly suggestive of an unstable fracture.
- High fibular fractures
- If the fracture is caused by a twisting injury, the fracture begins at the medial side.
- The ankle is unstable in almost all cases.
- If the fracture is caused by a direct blow, the treatment is conservative. Immobilization is usually not required.
Treatment
Stable ankle fractures
- Fractures of the lateral malleolus without medial injury (fracture or injury to the deltoid ligament), Weber A and B
- Conservative treatment
- A short leg cast worn for 2-4 weeks provides good pain relief.
- The patient may bear weight as tolerated.
- Treatment may also consist of wearing an orthosis.
- Repeat x-rays as considered necessary; usually not needed.
- Fractures of the medial malleolus without lateral injury may be treated conservatively but the decision is made in specialized care.
Unstable ankle fractures
- Treatment of unstable ankle fractures is surgical: emergency referral to specialized health care.
Reduction of a dislocated ankle
- The reduction must be carried out as soon as possible.
- Provide analgesia.
- Grasp the patient's foot by the heel with one hand whilst holding the lower leg tightly with the other.
- Reduce the dislocation by correcting the shortening and posterolateral displacement of the limb by applying downward and anteromedial traction to the heel.
- Apply a padded plaster cast or a supporting splint, and refer the patient for further treatment without delay.
- After surgery, the ankle is usually immobilised with a short plaster cast for 4-6 weeks. Weight bearing is decided individually.
Treatment of ankle fractures in special populations
- Ankle fractures in elderly patients are treated according to the same principles as those in younger patients.
- Ankle fractures in patients with diabetes, comorbidities, alcoholism, arteriosclerosis obliterans (ASO)
- Surgery is associated with more complications if
- the patient has neuropathy
- the peripheral pulses cannot be palpated.
- Decisions regarding treatment should be reserved for specialist health care.
References
- Herscovici D Jr, Scaduto JM, Infante A. Conservative treatment of isolated fractures of the medial malleolus. J Bone Joint Surg Br 2007 Jan;89(1):89-93. [PubMed]
- Kortekangas T, Haapasalo H, Flinkkilä T, et al. Three week versus six week immobilisation for stable Weber B type ankle fractures: randomised, multicentre, non-inferiority clinical trial. BMJ 2019;364:k5432. [PubMed]