eMedicine Specialties > Radiology > Musculoskeletal
Elbow, Fractures and Dislocations - Adult
Updated: May 1, 2009
Introduction
Background
Although the elbow is one of the most stable joints in the body, elbow dislocations and fractures are common. In adults, elbow dislocations are second only to shoulder dislocations in frequency; the elbow is the most frequently dislocated joint in pediatric patients.1
Elbow dislocations are classified as either simple or complex. Simple dislocations are classified by the direction of radial and/or ulnar displacement in relation to the distal part of the humerus. Complex elbow dislocations involve related fractures and/or neurovascular injuries.
Elbow fractures are classified as distal humeral, radial, and ulnar. The frequency of the different fracture types varies with the mechanism of injury and the age of the patient. In adults, radial head fracture is the most common type.
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 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. Lateral radiograph of the elbow demonstrates a superiorly displaced fracture of the capitellum.
For excellent patient education resources, visit eMedicine's Breaks, Fractures, and Dislocations Center. Also, see eMedicine's patient education articles, Elbow Dislocation and Broken Elbow.
Frequency
United States
Hildebrand et al reported that the annual incidence of elbow dislocations is 6-8 cases per 100,000 population2 ; these dislocations represent 11-28% of all injuries to the elbow. Posterior dislocations of the elbow are the predominant type and account for 80-90% of all elbow dislocations.
About 30% of elbow fractures in adults occur in the radial head. Olecranon process fractures account for 10-20% of all elbow injuries in adults.3,4 Coronoid process fractures occur in 10-15% of dislocations of the elbow.
Rare fractures in adults include those in the supracondylar humerus, capitellum, and trochlea. Fewer than 2% of elbow fractures affect the distal humerus. Capitellar fractures account for 0.5-1% of elbow injuries, and trochlear fractures are less common.5,6
International
Although international data are not readily available, the incidence and distribution likely correspond with those of the United States.
Mortality/Morbidity
Complications of elbow dislocations and elbow fractures are possible (see Clinical Details, Complications).
Age
The radial head fracture is the most common elbow fracture in adults (ie, individuals in whom the physes at the elbow have closed). See also Frequency.
- Supracondylar fractures occur mostly in children and adolescents with immature skeletons.
- Transcondylar fractures are more common in elderly persons with osteoporosis.
- Intercondylar fractures occur in persons 40-60 years old.
Presentation
Anatomy
The elbow is a hinge joint that comprises the following articulations:
- The humeroradial articulation, which is formed by the radial head and the capitellum of the humerus
- The humeroulnar articulation, which is formed by the ulnar notch and the trochlea of the humerus
- The superior radioulnar articulation, which is formed by the proximal parts of the radius and ulna.
Three intracapsular fat pads are present between the extensive synovia of the elbow and the joint capsule. The radial and coronoidal fossae fat pads appear radiographically as a single anterior fat pad. These fat pads are pressed into their respective fossae by the brachialis muscle during extension. The triceps brachii tendon and the anconeus muscle press the single posterior fat pad into the olecranon fossa during flexion.
Clinical presentation
The clinical presentations and mechanisms of injury in elbow fractures and dislocations vary. Almost all patients present in the acute care setting with history of recent trauma. Some patients may have a delayed presentation or even one that is remote from elbow injury; these patients must be thoroughly examined for associated morbidity.
ComplicationsComplications of elbow dislocations include the following:
- Posttraumatic periarticular calcification, which occurs in 3-5% of elbow injuries
- Myositis ossificans or calcific tendinitis3
- Neurovascular injuries (8-21% of cases) — ulnar nerve injuries are most common, followed by brachial artery injuries (5-13%)
- Osteochondral defects, intra-articular loose bodies, and avascular necrosis of the capitellum
- Instability
Complications of elbow fractures are possible. With supracondylar fractures, Volkmann ischemic contracture and malunion may occur; as with supracondylar fractures in general, these complications most commonly occur in children. With transcondylar fractures, loss of motion can result from callus formation in the olecranon or coronoid fossae. With intercondylar fractures, a loss of joint function may result. With condylar fractures, possible complications include nonunion, arthritis, cubitus varus or valgus deformity, and lateral transposition of the forearm. Coronoid process fractures, if left untreated, may lead to instability of the joint. With radial head fractures, a loss ofelbow extension and forearm rotation may result. With olecranon fractures, nonunion and loss of motion may result.
In the capitellum, traumatic arthritis, avascular necrosis of the fracture fragment, and limited range of motion may result.
If a radial head dislocation (eg, in a Monteggia fracture-dislocation) is overlooked, an irreducible radial head dislocation can cause pain and limit pronation and supination.
Preferred Examination
It has been suggested that radiologic studies may be unnecessary for the evaluation of elbow trauma if the active range of motion of the elbow remains normal8,9 ; even the ability to fully extend the elbow while in a supine position may be sufficient to obviate radiography.10,11 In such cases, patients may be advised to return in 7-10 days if their symptoms do not resolve.10
The preferred study for the evaluation of elbow trauma is conventional radiography.12 Radiographic examination requires the acquisition of 2 views: anteroposterior (AP) view in full extension and lateral view in 90° flexion. In children, oblique projections may be useful if the frontal and lateral projections do not show a fracture and fat pad signs are evident; internal oblique views are also valuable for providing further evaluation of lateral condylar fractures of the humerus in children.13
On radiographs, an anterior humeral line (see Image below) is parallel to the anterior cortex of the humerus. This line should intersect the distal, middle third of the capitellum. Displacement of this line suggests the presence of subtle supracondylar fractures.
Elbow, fractures and dislocations. Lateral radiograph of the elbow shows the anterior humeral line drawn along the anterior humeral cortex. This line passes through the middle third of the capitellum. The radiocapitellar line bisects the proximal radial shaft and extends through the capitellum in every view.
The radiocapitellar line (see Image above) extends through the axis of the radial head and neck. This line should intersect the midcapitellum on all radiographic views.
Displacement of the anterior fat pad, the radiographic sail sign (see Image below), may be present. The anterior fat pad is normally visualized on lateral radiographs as a triangular radiolucency. In the presence of joint effusion, this fat pad is displaced anteriorly, and the anterior margin becomes convex, similar to a billowing spinnaker sail. The presence of the sail sign should prompt further investigation for fractures. Fat pad signs may not be evident if the fracture is extracapsular.
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.
Posterior fat pad displacement may be observed. The posterior fat pad is not normally seen on radiographs, and its presence is always an abnormal finding that mandates further investigation for fractures.
When a fracture of the radial head, coronoid process, or capitellum is suspected, a radial head–capitellar view should be obtained. This view is a variant of the lateral projection that magnifies the structures and eliminates the overlap of joint surfaces. The view is obtained by positioning the patient with his or her forearm resting on the ulnar side, with the elbow flexed 90° and thumb pointing upward. The beam is pointed at the radial head with a 45° angle to the forearm.
Limitations of Techniques
Plain radiography is limited by the range of movement in an injured extremity, the patient's compliance, and the technique and ability of the technologist. The author recommends the careful removal of any splints prior to imaging to enable depiction of the greatest amount of radiographic detail.Differential Diagnoses
Other Problems to Be Considered
Fractures, Humerus
Fractures, Forearm
Trauma, Neurovascular Injuries
Neurovascular complications
Instability of the elbow secondary to ligamentous or tendinous injury
Heterotropic calcification and ossification of locally injured muscles, tendons, and ligaments
Intra-articular loose bodies and osteochondral defects
Avascular necrosis of the capitellum (Severe complex fracture-dislocation with involvement of the capitellum may result in compromise of its rather fragile blood supply.)
More on Elbow, Fractures and Dislocations - Adult |
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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
