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Ankle, Fractures
Article Last Updated: Jul 25, 2007
AUTHOR AND EDITOR INFORMATION
Section 1 of 11  
Author: Michael E Mulligan, MD, Associate Professor, Assistant Chief of Musculoskeletal Imaging, Department of Radiology, University of Maryland School of Medicine; Chief, Division of Radiology, Kernan Hospital
Michael E Mulligan is a member of the following medical societies: American Roentgen Ray Society, International Skeletal Society, Radiological Society of North America, and Society of Skeletal Radiology
Editors: Amilcare Gentili, MD, Clinical Professor of Radiology, University of California at San Diego; Consulting Staff, Department of Radiology, Thornton Hospital; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; Theodore E Keats, MD, Professor, Departments of Radiology and Orthopedics, University of Virginia School of Medicine; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; Felix S Chew, MD, MBA, EdM, Professor, Department of Radiology, Vice Chairman for Radiology Informatics, Section Head of Musculoskeletal Radiology, University of Washington
Author and Editor Disclosure
Synonyms and related keywords:
ankle fracture, broken ankle, fractured ankle, broken ankle bone, fractured ankle bone, fractured anklebone, broken anklebone, Ottawa ankle rules, broken foot, fractured foot, sprained ankle, twisted ankle
Background
The ankle is one of the most frequently injured areas of the skeleton. Although many of these injuries are ligament sprains, the radiologist plays a key role in the thorough evaluation of complex injuries and the detection of subtle fractures.
For excellent patient education resources, visit eMedicine's Breaks, Fractures, and Dislocations Center. Also, see eMedicine's patient education article Ankle Fracture.
Anatomy
The shapes of the ankle bones and the supporting ligamentous structures are important anatomic features of the ankle area. The distal tibia has a large, flat articular surface (the plafond), a prominent medial malleolus, and a less prominent posterior malleolus. The talar dome is wedge-shaped, wider anteriorly than posteriorly. The distal fibula or lateral malleolus is bound to the distal tibia by the anterior and posterior inferior tibiofibular ligaments, an inferior transverse ligament, and a syndesmosis ligament. The fibula is also bound to the talus by the anterior and posterior talofibular ligaments and to the calcaneus by the calcaneofibular ligament. The medial malleolus is bound to the talus, calcaneus, and navicular by the superficial and deep portions of the deltoid ligament.
Clinical Details
Patients with an ankle fracture usually will not be able to bear weight on the ankle and will have more swelling and pain than patients with just a ligament sprain. A site of point tenderness is often present with an ankle fracture, and an obvious deformity may be seen. The Ottawa Ankle Rules, developed by Stiell et al in Ottawa, Canada, are a set of guidelines that are used to determine whether radiography is necessary.1,2
Preferred Examination
Brandser et al recently emphasized the necessity of obtaining 3 conventional radiographs in anteroposterior, internal oblique (mortise), and lateral projections.3 Other imaging studies, such as arthrography, ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), and nuclear medicine, are rarely used. Radiographic stress views may be done, although they can be difficult to obtain. Stress views with dorsiflexion and external rotation of the ankle were reported by Park et al to best show tears of the deltoid ligament by resultant widening of the medial clear space when measured at 5 mm or more.4
Limitations of Techniques
Despite the use of the standard 3-view conventional radiographic survey, some ankle fractures cannot be seen at the time of initial evaluation. The presence of a large ankle-joint effusion on the initial lateral radiograph suggests an occult fracture. One third of patients with an effusion measuring 13 mm or more had occult fractures in a series reported by Clark et al.5 The radiographic appearance often suggests the presence of associated ligamentous injuries, but Gardner et al showed, in a series of 59 patients, that MRI is much more specific for ligamentous injuries.6 Additionally, although radiographic widening of the syndesmotic space of greater than 5 mm is reported to be abnormal, Nielson et al, in an MRI series of 70 patients, found no association between the MRI findings of syndesmotic injury and the radiographic measurements.7
Metatarsals, Fractures
Other Problems to Be Considered
Ankle sprain
Fifth metatarsal fracture
Talar dome osteochondral injury
Other surrounding ligament or tendon injury
Findings
Many ankle fractures occur in well-known, predictable patterns. Two similar classification schemes are frequently used to describe the findings: the Lauge-Hansen and the Danis-Weber (AO) classification systems. They are nearly identical, but they have different emphases for the radiologist and orthopedic surgeon, respectively.8 Since the Lauge-Hansen scheme is designed for radiologists, it will be emphasized here. The Lauge-Hansen classification scheme has 4 injury patterns: supination-adduction (SA, or Weber A in the Danis-Weber scheme), supination external rotation (SE, or Weber B), pronation-abduction (PA, or Weber C1), and pronation external rotation (PE, or Weber C2). The names of the Lauge-Hansen injury patterns can be thought of as indicating the initial position of the foot and hindfoot (supination or pronation) and the direction of the injuring force acting through the talus (adduction, abduction, external rotation). The location and type of fibula fracture are key to understanding the classification (see Image 1).
Supination adduction (SA, Weber A) The foot is supinated (inverted), and an adducting force is exerted on the talus, resulting in 2 sequential injuries. First, tension on the lateral ligaments (the calcaneofibular ligament, primarily) leads to a transverse fracture of the lateral malleolus below or up to the level of the tibiofibular joint, or a ligament tear occurs. Second, the talus adducts, impacts the medial malleolus, and causes an oblique medial malleolar fracture (see Image 2). Supination external rotation (SE, Weber B) This is the most common mechanism for a "twisted ankle" injury. The foot is supinated, and an external rotation force acts on the talus, resulting in up to 4 sequential injuries (see Images 3-4): - First, the anteroinferior tibiofibular ligament tears.
- Second, a short oblique fracture of the fibula occurs (which is best seen on lateral radiographs).
- Third, fracture of the posterior malleolus is observed.
- Fourth, transverse fracture of the medial malleolus or tear of the deltoid ligament occurs. (Sorrento and Mlodzienski also reported lesions of the lateral aspect of the talar dome in 38% of patients with SE stage 4 injuries.)9
Pronation abduction (PA, Weber C1) The foot is in a pronated position (everted), and an abducting force is exerted on the talus, resulting in up to 3 sequential injuries: - First, the deep portion of the deltoid ligament becomes tense and a transverse fracture of the medial malleolus occurs.
- Second, the talus abducts and stresses the ligaments of the tibiofibula syndesmosis, resulting in a tear of the anteroinferior tibiofibula ligament.
- Third, further abduction of the talus results in oblique fracture of the distal fibula (see Image 5). This fibula fracture ends just above the level of the joint line and is best seen on anteroposterior (AP) or mortise views. It may not be visible on lateral radiographs. Injury of the syndesmosis should be suggested when the distance between the lateral edge of the tibia and the medial edge of the fibula measures more than 5 mm on either AP or mortise views, as reported by Sclafani.10
Pronation external rotation (PE, Weber C2) The foot is in a pronated position (everted), and an external rotation force acts through the talus, resulting in up to 4 sequential injuries (see Images 6-7): - The first 2 injuries are the same as in the pronation abduction (PA) mechanism (medial malleolar fracture and syndesmosis injury; see above).
- For the third injury, the external rotation force results in a different fibula fracture. It is a short spiral or oblique fracture well above the level of the syndesmosis (usually 6-8 cm above the syndesmosis but may be as high as the mid-shaft level).
- The fourth injury is a fracture of the posterior malleolus.
Maisonneuve fracture (Weber C3) The exact mechanism leading to a Maisonneuve fracture is not clear. The injury sequence clearly differs from those above as described by Pankovich.11 - First, a tear of the anteroinferior tibiofibula ligament and the interosseous membrane occurs.
- Second, fracture of the posterior malleolus or a posterior ligament tear is observed.
- Third, anteromedial capsular injury is present.
- Fourth, fracture of the proximal fibula occurs (usually at the neck).
- Fifth, fracture of the medial malleolus or a deltoid ligament tear is observed (see Images 8-9). (The timing of the last injury in this mechanism distinguishes it from pronation injuries, where the medial malleolar fracture is the first injury in the sequence.)
Pilon (pylon) fracture Some of the fracture patterns listed above include fractures of the medial malleolus or posterior malleolus, but the articular surface of the tibia, the plafond, is uninvolved (see Image 1). Pilon (pylon) fractures are comminuted fractures involving the plafond. Many other associated fractures may exist, including any or all of the malleoli. The key feature is comminution of the distal tibia articular surface (see Images 10-12). Most authorities now include the old Lauge-Hansen type pronation dorsiflexion injury as a pilon-type fracture.12 Salter-Harris fractures All types of Salter-Harris injury may involve the distal tibia or fibula. Most simple Salter-Harris fractures of the distal tibia are type 2 (they have a metaphyseal component). Special types of Salter-Harris injury in the ankle region include the triplane and juvenile Tillaux fractures. Triplane fracture As the name implies, fractures are seen in 3 different axes (planes) with triplane fracture: an axial or horizontal injury through the distal tibia physis, a sagittal component through the distal tibia epiphysis, and a coronal component posteriorly through the distal tibia metaphysis (see Images 13-14). Juvenile Tillaux/Tillaux In children, a Tillaux fracture is basically a Salter-Harris type 3 fracture of the distal tibia epiphysis that occurs, by definition, at the lateral edge of the epiphysis from tensile avulsion by the syndesmotic ligaments (see Images 15-16). Its adult counterpart is simply a Tillaux fracture, and the fibula avulsion counterpart is a Wagstaff-LeFort fracture.
Findings
CT is not needed for the evaluation of most ankle fractures. It may be used to better define pilon fractures or triplane fractures. Thin overlapping sections should be taken in case coronal and sagittal reconstructions are needed, or newer multislice isotropic techniques should be used.
Findings
MRI is not needed for the evaluation of most ankle fractures. It can show additional injuries in children with Salter-Harris fractures. MRI also may be used to check for occult injuries, especially injuries of the talar dome, or soft-tissue injuries, such as surrounding ligament or tendon abnormalities.
Findings
Ultrasound is not usually employed in the United States for the evaluation of patients with ankle fractures. It can depict fractures and associated soft-tissue injuries, especially injuries of the peroneal tendons. In addition, Hsu et al found ultrasonography to be useful for identifying ligament injuries in patients with inversion ankle sprains.13
Findings
Bone scintigraphy is not needed for the evaluation of most ankle injuries. It can be used to look for occult injuries, especially injuries of the talar dome.
Medical/Legal Pitfalls
- As some ankle fractures are initially occult, patients with significant injury should be treated symptomatically and asked to return for additional radiographs in 7-10 days if symptoms persist. The physician should pay special attention to certain target areas, such as the medial and lateral edges of the talar dome, the anterior process of the calcaneus, and the base of the fifth metatarsal, in order to check for subtle fractures.
| Media file 1:
Diagram showing the typical locations for ankle fractures occurring from the 4 major injury mechanisms (SA= supination adduction, SE= supination external rotation, PA= pronation abduction, PE= pronation external rotation). Note that the SE fracture is shown as a dashed line, since it is best seen in the lateral projection. |
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| Media file 2:
A 37-year-old man with a supination adduction stage 2 ankle injury as a result of a motor vehicle collision. Anteroposterior radiograph shows a small avulsion fracture at the tip of the lateral malleolus (stage 1) and an oblique fracture across the base of the medial malleolus (stage 2). |
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A 31-year-old woman with a supination external rotation stage 2 ankle injury. Anteroposterior radiograph only shows lateral soft-tissue swelling. |
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| Media file 4:
Lateral radiograph (same patient as in Image 3) shows short oblique fracture of the distal fibula that extends to the level of the tibiotalar joint line (supination external rotation stage 2 injury). Note that there is no fracture of the posterior malleolus (stage 3) or medial malleolus (stage 4). |
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A 22-year-old man with a posteroanterior stage 3 ankle injury. Anteroposterior radiograph shows medial soft-tissue swelling, indicating ligamentous injury (stage 1) and an oblique fracture of the fibula just above the level of the tibiofibular syndesmosis (stage 3 injury). Syndesmosis injury (stage 2) is not evident in this patient. |
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| Media file 6:
A 27-year-old woman with a pronation external rotation–type ankle injury. Anteroposterior radiograph shows fracture of the medial malleolus (stage 1), widening of the tibiofibular syndesmosis (indicating ligamentous tear, stage 2), and a high fibula fracture (stage 3). |
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Lateral radiograph (same patient as in Image 6) shows additional fracture of the posterior malleolus, making this a pronation external rotation stage 4 injury. |
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Maisonneuve injury. Mortise view shows transverse fracture of the medial malleolus and widening of the tibiofibular syndesmosis without a fracture of the fibula. This injury is suggestive of a proximal fibula fracture (Maisonneuve fracture). |
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Lateral radiograph (same patient as in Image 8), taken after a short leg cast was applied and the patient reported pain, reveals Maisonneuve fracture of the proximal fibula. |
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Pilon fracture in a 35-year-old man who fell 20 ft. Anteroposterior radiograph shows at least 2 fracture lines extending to the articular surface (plafond) of the tibia. |
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Axial CT section (from multislice acquisition) of a 35-year-old man (same patient as in Images 10 and 12) shows comminution of the tibial plafond. |
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Coronal reformation (from multislice CT data) of a 35-year-old man (same patient as in Images 10 and 11) shows comminution of the plafond as well as the step-off and gap between fracture fragments. |
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A 13-year-old girl with triplane fracture. Anteroposterior radiograph shows a sagittal component through the distal tibia epiphysis. |
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Lateral radiograph of the same patient as in Image 13 shows slight axial (horizontal) displacement of the distal tibia epiphysis relative to the distal tibia metaphysis, with widening of the anterior aspect of the physis and a coronally oriented fracture through the distal tibia metaphysis. |
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An 11-year-old girl with juvenile Tillaux fracture. Mortise view shows fracture involving the lateral portion of tibial epiphysis. |
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| Media file 16:
Axial CT section, taken with a cast around the ankle, confirms the radiographic finding of a fracture fragment at the lateral aspect of the tibial epiphysis (same patient as in Image 15). Note that no other fracture lines are present. |
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Ankle, Fractures excerpt Article Last Updated: Jul 25, 2007
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