Diagnostic Imaging Pathways - Ankle Injury
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This pathway provides guidance on imaging adult patients with suspected traumatic ankle injuries. It incorporates the Ottawa Ankle Rules.
Date reviewed: August 2013
Date of next review: August 2015
Published: August 2013
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|SYMBOL||RRL||EFFECTIVE DOSE RANGE|
|Minimal||< 1 millisieverts|
- Ankle radiograph series (based on the OTTAWA Ankle rules) is indicated if there is pain near either of the malleoli AND either of the following
- Inability to weight bear both immediately and in the emergency department (4 steps)
- Bone tenderness at the posterior edge or tip of either malleolus
- Foot radiograph series is indicated if there is pain in the midfoot AND either of the following findings
- Inability to weight bear immediately and in the emergency department (4 steps)
- Bone tenderness at the navicular or the base of the 5 th metatarsal
- CT of the ankle should be considered for pre-operative planning or when persistent clinical suspicion of fracture persists despite normal plain radiographs
- MRI may be useful in assessing for ligamentous injuries
Computed Tomography (CT) of the Ankle
- Should be considered if there is ongoing suspicion of a fracture despite a negative radiograph
- May be useful with chronic post-traumatic residual ankle pain in the presence of normal plain radiograph
- Fractures of the lateral process of the talus are negative with up to 40% of plain radiographs. They are most common in snowboarders and should be suspected when there is a history of inversion with dorsiflexion, together with tenderness over the lateral aspect of the talus
Magnetic Resonance Imaging (MRI) of the Ankle
- Detects complete lateral ankle ligament rupture with a sensitivity of 50-74% and specificity of 100%
- MRI of the ankle for ligamentous injury is not performed routinely as most injuries heal with sufficient strength to maintain joint stability and findings do not consistently correlate with clinical outcome
- The only indication for primary surgical repair of the acutely torn ligament may be in high-performance athletes ,
- Appearance of ligamentous injury on MRI include ,,,
- Irregular ligamentous thickening with occasional increased signal intensity within partially torn ligaments
- Discontinuity of the ligament with ligamentous stumps, heterogenous appearance, and fluid signal bridging the defect characterise completely ruptured ligaments
- Non specific findings of ligamentous injury include soft tissue oedema or haemorrhage, joint effusion, extravasation of joint fluid outside the capsule, and bone bruising
- Advantages of MRI
- Superior soft tissue resolution and tissue characterisation
- Less operator dependent compared to ultrasound
- Higher cost compared to ultrasound and stress radiography
- Longer examination times
- Inability to predict clinical outcome
Ottawa Ankle Rules
- Clinical decision rules derived for the use of ankle and foot radiographs after an acute ankle injury
- These rules were refined and validated prospectively on 453 patients
- Implementation of the rules resulted in a decrease in the use of ankle radiography by 28% and foot radiography by 14% without affecting the incidence of fracture detection
- The Ottawa Ankle Rules have also been prospectively applied in several other studies and in all but one have resulted in a significant reduction in the use of ankle and foot radiographs (19-34%) without missing any clinically significant fractures
- For detection of lateral ankle ligamentous rupture, ultrasound has a sensitivity of 85% and specificity of 94%.
- Most cases of suspected ligamentous injury will not require imaging as conservative management is appropriate for most acute injuries.
- Sonographic appearances of ligamentous injury include: ,
- Hypoechoic thickening of the ligament with incomplete tears.
- With complete ligamentous rupture, the hyperechoic ligament has a wavy contour appearance, with a hypoechoic or anechoic gap (oedema or haematoma) between the ends of the torn ligament.
- Bony avulsion fragments may be demonstrated.
- Advantages compared to MRI:
- Direct correlation of sonographic findings with patient symptoms and rapid comparison of the asymptomatic ankle.
- Wide availability of ultrasound equipment.
- Lower cost compared to MRI
- More rapid examination than standard MRI examination.
- Unknown correlation of findings with clinical outcome
- Operator dependent
- Structures immediately superficial to the bony cortex may be difficult to assess.
Plain Radiography of the Ankle and Foot
- An ankle x-ray series usually consists of AP, lateral and mortise views. The fifth metatarsal distal to the tuberosity should be seen in at least one projection
- The presence of an ankle effusion is best appreciated on the lateral view and is an important finding because it increases the likelihood of an occult fracture
- In one study the presence of an ankle effusion correlated with the presence of an occult fracture in between 35% and 85% of patients, depending on the actual size of the effusion
- A foot x-ray series usually consists of AP, oblique and lateral views
References are graded from Level I to V according to the Oxford Centre for Evidence-Based Medicine, Levels of Evidence. Download the document
- Stiell IG, Greenberg GH, McKnight RD, et al. A study to develop clinical decision rules for the use of radiography in acute ankle injuries. Ann Emerg Med. 1992;21:384-90. (Level II evidence) View the reference
- Stiell IG, Greenberg GH, McKnight RD, et al. Decision rules for the use of radiography in acute ankle injuries. JAMA. 1993;269:1127-32. (Level I evidence) View the reference
- Stiell IG, McKnight RD, Greenberg GH, et al. Implementation of the Ottawa ankle rules. JAMA. 1994;271:827-32. (Level I evidence) View the reference
- Ho K, Connell HK, Janzen DL, et al. Using tomography to diagnose occult ankle fractures. Ann of Emerg Med. 1996;27:600-5. (Level IV evidence)
- Meyer JM, Hoffmeyer P, Savoy X. High resolution computed tomography in the chronically painful ankle sprain. Foot & Ankle. 1988;8:291-6. (Level IV evidence)
- Chan GM, Yoshida D. Fracture of the lateral process of the talus associated with snowboarding. Ann Emerg Med. 2003;41:854-8. (Level IV evidence)
- Kelly AM, Richards D, Kerr L, et al. Failed validation of a clinical decision rule for the use of radiography in acute ankle injury. N Z Med J. 1994;107:294-5. (Level II evidence) View the reference
- Lucchesi GM, Jackson RE, Peacock WF et al. Sensitivity of the Ottawa rules. Ann Emerg Med. 1995;26:1-5. (Level II evidence) View the reference
- Pigman EC, Klug RK, Sanford S et al. Evaluation of the Ottawa clinical decision rules for the use of radiography in acute ankle and midfoot injuries in the emergency department: an independent site assessment. Ann Emerg Med. 1994;24:41-5. (Level II evidence) View the reference
- Stiell IG, Wells G, Laupacis A, et al. A muliticentre trial to introduce the Ottawa ankle rules for use of radiography in acute ankle injuries. BMJ. 1995;311:594-7. (Level II evidence) View the reference
- Papacostas E, Malliaropoulos N, Papadopoulos A, Liouliakis C. Validation of Ottawa ankle rules protocol in Greek athletes: study in the emergency departments of a district general hospital and a sports injuries clinic. Br J Sports Med. 2001;35:445-7. (Level II evidence)
- Leddy JJ, Smolinski RJ, Lawrence J et al. Prospective evaluation of the Ottawa ankle rules in a university sports medical center. Am J Sports Med. 1998;26:158-65. (Level II evidence)
- Fessell DP, van Holsbeeck MT. Foot and Ankle Sonography. Radiol Clin North Am. 1999;37(4):831-58. (Review article)
- Milz P, Milz S, Steinborn M et al. Lateral ankle ligaments and tibiofibular syndesmosis. Acta Orthop Scand. 1998;69(1):51-5. (Level IV evidence)
- Breitenseher MJ, Trattnig S, Kukla C, et al. MRI versus lateral stress radiography in acute lateral ligamentous injuries. J Comput Assist Tomogr. 1997;21(2):280-5. (Level IV evidence)
- Cheung Y, Rosenburg ZS. MR imaging of ligamentous abnormalities of the ankle and foot. MRI Clincs North Am. 2001;9(3):507-31. (Review article)
- Dunfee WR, Dalinka MK, Kneeland JB. Imaging of athletic injuries to the ankle and foot. Radiol Clincs North Am. 2002;40:289-312. (Review article)
- Zanetti M, De Simoni C, Wetz HH, Zollinger H, Hodler J. Magnetic resonance imaging of injuries to the ankle joint: can it predict clinical outcome? Skeletal Radiol. 1997;26:82-8. (Level III/IV evidence)
- Morrison WB. Magnetic resonance imaging of sports injuries of the ankle. Top Magn Reson Imaging. 2003;14(2):179-98. (Review article)
- Pinar H, Akseki D, Kovanlikaya I, Arac S, Bozkurt M. Bone bruises detected by magnetic resonance imaging following lateral ankle sprains. Knee Surg Sports Traumatol Arthrosc. 1997;5:113-7. (Level III evidence)
- Jacobson JA, van Holsbeeck MT. Musculoskeletal imaging update, Part II: musculoskeletal ultrasonography. Orthop Clin North Am. 1998;29(1):135-67. (Review article)
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