eMedicine Specialties > Radiology > Musculoskeletal
Elbow, Fractures and Dislocations - Adult: Imaging
Updated: May 1, 2009
Radiography
Elbow, fractures and dislocations. Anteroposterior (AP) radiograph of the forearm demonstrates a posterior dislocation of the elbow. Note the discontinuity of the radiocapitellar line. Also note the overlap of the articular surfaces of the trochlea and ulna.
Elbow, fractures and dislocations. Lateral view of the forearm demonstrates a posterior dislocation of the radius and ulna in relation to the distal humerus.
Elbow, fractures and dislocations. Lateral view of the elbow demonstrates a posterior dislocation of the elbow. The patient also had a nondisplaced radial head fracture.
Elbow, fractures and dislocations. Lateral view shows an elbow with a subtle radial head fracture. The presence of the sail sign and the posterior fat pad suggest an associated fracture.
Elbow, fractures and dislocations. Radial head–capitellar view demonstrates a nondisplaced fracture of the radial head. This fracture was not seen on the lateral radiograph.
Elbow, fractures and dislocations. Lateral radiograph of the elbow demonstrates a superiorly displaced fracture of the capitellum.
Elbow, fractures and dislocations. Lateral view of the elbow demonstrates a displaced olecranon fracture.
Elbow, fractures and dislocations. Lateral view of the elbow demonstrates a displaced radial neck fracture.
Elbow, fractures and dislocations. Anteroposterior (AP) radiograph of the elbow demonstrates a T-type condylar fracture.
Elbow, fractures and dislocations. Lateral radiograph of the elbow demonstrates a comminuted supracondylar fracture.
Findings
Elbow dislocations
Adult elbow dislocations are classified by the direction of displacement and the presence or absence of associated fractures. Simple elbow dislocations are solely soft tissue injuries. The direction can be anterior, posterior, lateral, or divergent. The most common dislocation involves posterior displacement of both the radius and ulna in relation to the distal humerus. Less common dislocations are the following: medial and lateral dislocations, anterior dislocations, translocation of the elbow, divergent dislocations, and isolated dislocations of either the radius or ulna.
Complex elbow dislocations have associated fractures that compromise joint stability. The most common associated fractures are those of the radial head and coronoid process. The combination of posterior elbow dislocation, radial head fracture, and coronoid fracture has been termed the "terrible triad".14 Associated injuries involving structures other than the elbow (eg, the shoulder, distal radius or ulna, and carpal bones) occur in 10-15% of cases.2
The Essex-Lopresti fracture-dislocation consists of a comminuted radial head fracture and a distal radioulnar joint dislocation, along with tearing of the interosseus membrane; it typically results from high-energy trauma.15
Monteggia fracture-dislocations involve ulnar fracture accompanied by dislocation of the radial head. Table 1 summarizes the Bado classification system for Monteggia fracture-dislocations.
Table 1. Bado Classification of Monteggia Fracture-Dislocation
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Table
| Type | Description | Frequency, % 3 |
|---|---|---|
| I | Fracture of the middle or proximal third of the ulna and anterior dislocation of the radial head | 65 |
| II | Fracture of the middle or proximal third of the ulna and posterior dislocation of the radial head | 18 |
| III | Ulnar fracture distal to the coronoid process with lateral radial head dislocation | 16 |
| IV | Fracture of the proximal or middle third of the ulna with an anterior dislocation of the radial head and fracture of the proximal third of the radius | 1 |
| Type | Description | Frequency, % 3 |
|---|---|---|
| I | Fracture of the middle or proximal third of the ulna and anterior dislocation of the radial head | 65 |
| II | Fracture of the middle or proximal third of the ulna and posterior dislocation of the radial head | 18 |
| III | Ulnar fracture distal to the coronoid process with lateral radial head dislocation | 16 |
| IV | Fracture of the proximal or middle third of the ulna with an anterior dislocation of the radial head and fracture of the proximal third of the radius | 1 |
Mechanism of injury
Most dislocations occur as a result of a fall on an outstretched hand (FOOSH). Elbow dislocations and fractures can also occur with a high-energy direct impact.
Preferred examination
AP and lateral radiographs of the elbow are most effective in demonstrating elbow dislocations. Postreduction films should be examined for associated fractures. Radiographic findings include displacement of the radius and/or ulna relative to the distal humerus, with or without evident fracture lines.
Elbow fractures
Elbow fractures are classified into 3 categories: (1) distal humerus fractures, (2) proximal radius fractures, and (3) proximal ulna fractures.
Table 2. Muller Classification of Distal Humerus Fractures
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Table
| Location | Description |
| Extra-articular | Avulsion of medial and/or lateral epicondylar fracture Simple supracondylar fracture Comminuted supracondylar fracture |
| Intra-articular - Transcondylar | Trochlea fracture Capitellum fracture |
| Intra-articular - Bicondylar, intercondylar | Y-shaped bicondylar fracture Y-shaped Intercondylar fracture with supracondylar comminution Complex comminuted fracture |
| Location | Description |
| Extra-articular | Avulsion of medial and/or lateral epicondylar fracture Simple supracondylar fracture Comminuted supracondylar fracture |
| Intra-articular - Transcondylar | Trochlea fracture Capitellum fracture |
| Intra-articular - Bicondylar, intercondylar | Y-shaped bicondylar fracture Y-shaped Intercondylar fracture with supracondylar comminution Complex comminuted fracture |
Supracondylar fractures
Supracondylar fractures are the most common elbow fractures in pediatric patients. Typically, patients are 3-10 years old. In the immature skeleton, the collateral ligaments and joint capsule are stronger than the bone. The opposite is true in the mature skeleton. Therefore, supracondylar fractures seldom occur in adults. Two types of supracondylar fractures are possible: flexion fractures and extension fractures. These types are subdivided into categories on the basis of displacement and cortical integrity. Also, because the immature elbow has developing physes, Salter-Harris fractures may occur.
Salter-Harris type I supracondylar fractures occur most frequently in infants and toddlers. The Salter-Harris type I fracture affects only the physis, with separation of the epiphysis from the metaphysis. These fractures are minimally displaced or nondisplaced. Radiographic findings are subtle and include the presence of a posterior fat pad due to hemarthrosis or perhaps a widening of the physis.
Elbow dislocations may be mistaken for Salter-Harris type I supracondylar fractures. Correct distinction is important because an improperly treated dislocation can lead to chronic joint dysfunction. In a physeal separation, the relationship of the capitellum to the humerus is disrupted while that of the capitellum to the radial head remains normal. In an elbow dislocation, the alignment between the radial head and capitellar epiphysis is lost. Further cross-sectional imaging may be necessary to delineate the injury.
True supracondylar fractures may result from trauma during extension (eg, FOOSH with the elbow in full extension) or flexion (eg, direct impact to a flexed elbow). The preferred studies are AP and lateral radiographs, with CT as needed to assess the position of comminuted fragments. Radiographic findings include a fracture line proximal to the humeral epicondyles, joint effusion (eg, fat pad sign), and disruption of the anterior humeral line. Treatment for a nondisplaced fracture is immobilization. Patients with a displaced fracture should be referred to an orthopedist.
Transcondylar fractures
Transcondylar fractures are classified into flexion and extension types on the basis of the position of the elbow during impact. The mechanism of injury is a FOOSH. The preferred studies are AP and lateral radiographs and CT to assess the position of comminuted fragments. On the images, the fracture line extends through the condyles proximal to the articular surface. Treatment is difficult, because the amount of bone available for proper union is limited; the patient should be referred to an orthopedist.
Intercondylar fractures
These are T- or Y-shaped fractures with varying amounts of displacement between the condyles and from the humerus. The mechanism of injury is indirect trauma: the olecranon is forced against the articular surface of the humerus and splits the end of the humerus. The preferred studies are AP and lateral radiographs; CT can be used to guide surgical intervention. On the images, a fracture is present between condyles, and the condyles are separated from the humeral shaft. Treatment is open reduction and internal fixation (ORIF).
Condylar fractures
These fractures are divided into medial and lateral condylar fractures. Lateral condyle fractures are more common. The mechanism of injury with lateral fractures is direct impact to the lateral elbow during flexion; medial fractures involve an impact to the olecranon process with a flexed elbow. The preferred study is plain radiography; CT is used as needed. Radiographic findings include a widened intercondylar distance with lateral fractures; commonly, a fragment is posteriorly and inferiorly displaced. With medial fractures, the fragment is commonly anteriorly and inferiorly displaced. Fractures typically involve the joint surface and nonarticular parts of the distal humerus. Treatment for nondisplaced fractures is immobilization. Fractures that are displaced by more than 3 mm require surgical fixation.
Capitellar fractures
A capitellar fracture is one that involves the articular surface of the distal humerus. Most commonly, these occur with posterior elbow dislocations. The mechanism of injury is a FOOSH in which the radial head shears the capitellum. The preferred study is lateral elbow radiography. On radiographs, the fragment is medial relative to the normal position, with visible joint effusion. The treatment of nondisplaced fractures is immobilization.
Displaced fractures require surgical treatment.16 In a prospective, randomized study by McKee et al of elderly patients with displaced, intra-articular distal humeral fractures, total elbow arthroplasty (TEA) was found in many instances to provide superior results compared with open reduction and internal fixation (ORIF). Of 21 patients randomized to ORIF, 5 needed to be converted to TEA because of unstable fixation. Operative time was 32 minutes less for the TEA group. Mayo Elbow Performance Scores (MEPSs) were significantly better for TEA patients at 3 months, 6 months, 12 months, and 2 years. TEA patients also had better DASH (Disabilities of the Arm, Shoulder, and Hand) scores at 6 weeks and 6 months, but not at 1 year or at 2 years follow-up. TEA patients had a mean flexion-extension arc of 107º; ORIF patients, 95º. TEA may therefore be preferred for elderly patients with complex distal humeral fractures.17
Olecranon fractures
The many classifications of olecranon fractures are based on the displacement, the number of fracture lines, and the subdivisions of the olecranon process. No classification system is universally accepted. The mechanism of injury is a direct impact or FOOSH. The preferred study is lateral radiography. Radiographs demonstrate the fracture and amount of displacement. Displaced fractures are defined by a separation of more than 2 mm or increased separation with elbow flexion. On radiographs, a fracture line is evident through the olecranon process. The treatment for nondisplaced fractures is immobilization. Displaced fractures require ORIF.
Mason fractures
Mason fractures are radial head fractures; they are classified into 4 types, as shown in Table 3.
Table 3. Mason Classification of Fractures
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Table
| Type | Fracture |
| I | Nondisplaced |
| II | Marginal with displacement |
| III | Comminuted |
| IV | With elbow dislocation |
| Type | Fracture |
| I | Nondisplaced |
| II | Marginal with displacement |
| III | Comminuted |
| IV | With elbow dislocation |
The mechanism of injury is a FOOSH that forces the radial head against the capitellum. The preferred study is lateral radiography of the anterior aspect of the radial head and the radial head and capitellum to evaluate the posterior aspect of the radial head or occult fractures. Radiographic findings vary from comminution to marginal fractures involving impaction, depression, or angulation. Nondisplaced fractures may result in only a posterior fat pad or the anterior sail sign.
The treatment of type I and type II fractures is joint aspiration followed by immobilization. Radial head osteoplasty may be required in fractures that fail to heal. Type III fractures and type II fractures with a mechanical block are treated with radial head revision. Type IV fractures are first treated for dislocation and then for the fracture, according to its Mason classification. Other indications for ORIF include cleavage fractures of the articular surface involving one third of the head or 3- to 4-mm displacement involving half of the radial head.
Degree of Confidence
As discussed in Limitations of Techniques, plain radiographs can be limited by patient positioning, patient compliance, and technique. The sail sign and posterior fat pad should always raise suspicion if fractures are not evident; in patients with these findings, the authors recommend conservative treatment and repeat plain radiography in 7-10 days. Cross-sectional imaging should be reserved for surgical planning in the acute setting and for later evaluation of associated soft tissue involvement.
False Positives/Negatives
False-positive findings may be caused by the misinterpretation of a normal anterior fat pad or, more likely, by the presence of old avulsive injuries of the condyles. False-negative readings depend on the skill of the interpreting physician, the quality of the studies, and the conspicuity of the fractures.
Computed Tomography
Elbow, fractures and dislocations. Axial CT scan of the elbow demonstrates a displaced capitellar fracture. This image was obtained for surgical planning.
Findings
CT is selectively used in acute or subacute settings to evaluate the displacement of fractures or to delineate osteochondral fragments in the joint.
Degree of Confidence
If thin-section multidetector-row CT is complemented with multiplanar reconstructions, the degree of confidence in the findings is high.
Magnetic Resonance Imaging
Elbow, fractures and dislocations. Axial T1-weighted MRI of the elbow demonstrates an ossific fragment from a prior injury that caused ulnar nerve impingement. Associated abnormal hyperintensity is depicted in the ulnar nerve. The patient presented with radicular pain in the ulnar distribution after a prior fracture-dislocation of the elbow.
Findings
MRI has a limited role in the acute setting. In the subacute setting, MRI is invaluable in the assessment of the collateral ligaments; common extensor and flexor tendon originations; articular cartilage; and, to a lesser extent, occult fractures. MRI and MRI arthrography are superior to CT arthrography for detecting occult bone injuries in the elbow.18 MRI can detect the osteochondral and ligamentous injuries that often accompany acute radial head fractures (Mason type II and III).
MRI may be used to assess the status of the interosseus membrane when a longitudinal radioulnar dissociation is suspected. Also, MRI can be used to visualize major neurovascular structures that cross the joint.
As peripheral magnetic resonance angiography (MRA) is more widely used, it may come to have a role in the assessment of acute vascular injury in the elbow.
Angiography
Findings
Arteriography is rarely indicated in the absence of definite signs of arterial injury (eg, pulsatile hemorrhage, absent distal pulses, overt distal ischemia, audible bruit, and a palpable thrill). Arteriography is primarily used to assess the brachial artery at the elbow. Transection, thrombosis, dissection, and intimal flaps may be found.
More on Elbow, Fractures and Dislocations - Adult |
| Overview: Elbow, Fractures and Dislocations - Adult |
 Imaging: Elbow, Fractures and Dislocations - Adult |
| Follow-up: Elbow, Fractures and Dislocations - Adult |
| Multimedia: Elbow, Fractures and Dislocations - Adult |
| References |
| Further Reading |
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References
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Further Reading
Related eMedicine topics
Arthrocentesis, Elbow
Joint Reduction, Elbow Dislocation, Posterior
Elbow Trauma, Pediatric
Elbow, MRI
Elbow Dislocation
Medial Condylar Fracture of the Elbow
Clinical guidelines
Evidence-based care guideline for loss of elbow motion following surgery or trauma in children aged 4 to 18. Cincinnati Children's Hospital Medical Center - Hospital/Medical Center. 2007 Dec. 9 pages. NGC:006291
Elbow (acute & chronic). Work Loss Data Institute - Public For Profit Organization. 2003 (revised 2008 May 28). 161 pages. NGC:006555
ACR Appropriateness Criteria® chronic elbow pain. American College of Radiology - Medical Specialty Society. 1998 (revised 2005). 5 pages. [NGC Update Pending] NGC:004605
Clinical trials
Progressive Splinting Status Post Elbow Fractures and Dislocations
Treatment of Stable Both-Bone Midshaft Forearm Fractures in Children
Effect of Occupational Therapy on the Function and Mobility of Elbow Fractures
Discovery Elbow Multi-Center Prospective Study
Keywords
humerus fractures, distal humeral fractures, radial fractures, ulnar fractures, forearm trauma, neurovascular injuries, Monteggia fracture-dislocation, simple elbow dislocation, complex elbow dislocation, fall on an outstretched hand, FOOSH
