AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Angiography
• Intervention
• Multimedia
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Angiography
• Intervention
• Multimedia
• References

Background

Although the elbow is one of the most stable joints in the body, elbow dislocations and fractures are common.

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 fractures, radial fractures, and ulnar fractures. Fractures vary with the mechanism of injury and the age of the patient. The radial head fracture is the most common fracture in adults.

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.

Pathophysiology

The type of dislocation and/or fracture varies with the mechanism, age of the patient, and force causing the injury.

Frequency

United States

Hildebrand et al reports that the annual incidence of elbow dislocations is 6-8 cases per 100,000 population; these dislocations represent 11-28% of all injuries to the elbow. The frequency of elbow dislocations is second to that of dislocations of the shoulder. 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 20% of all elbow injuries in adults (Resnick, 1992). 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. Mehdian states that capitellar fractures account for 0.5-1% of elbow injuries, and trochlear fractures are less common.

International

Although international data are not readily available, the incidence and distribution likely reflect those of the United States.

Mortality/Morbidity

Complications of elbow dislocations and elbow fractures are possible (see Clinical Details, Complications).

Race

Elbow fractures and dislocations have demographic features similar to those of other traumas.

Age

The radial head fracture is the most common elbow fracture in adults. In this context, adults are individuals in whom the physes at the elbow are closed physes. See also Frequency.

• Most supracondylar fractures occur in those with immature skeletons.
• Transcondylar fractures are more common in elderly people with osteoporosis.
• Intercondylar fractures occur in those aged 40-60 years.

Anatomy

The elbow is a hinge joint that is composed of the following articulations: 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; and the superior radioulnar articulation, which is formed by the proximal part of the ulna and radius. Muscles and ligaments connect the structures. A fibrous capsule surrounds the joint, and the radial and ulnar collateral ligaments reinforce it.

Three intracapsular fat pads are present between the extensive synovia of the elbow and the joint capsule. The radiographic anterior fat pad is composed of the radial and coronoidal fossae fat. 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 Details

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.

Complications

Complications of elbow dislocations include the following: posttraumatic periarticular calcification, which occurs in 3-5% of elbow injuries; myositis ossificans or calcific tendinitis (Resnick, 1992); neurovascular injuries (in 8-21% of cases), in which 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; and instability.

Complications of elbow fractures are possible. With supracondylar fractures, Volkmann ischemic contracture and malunion most commonly occur in children. With transcondylar fractures, the 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, nonunion, arthritis, cubitus varus or valgus deformity, and lateral transposition of the forearm may occur. If coronoid process fractures are untreated, they may lead to instability of the joint. With radial head fractures, a loss of elbow extension and rotation of forearm 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.

Monteggia fracture-dislocations can occur. If a radial head dislocation is overlooked, an irreducible radial head dislocation can cause pain and limit pronation and supination.

Preferred Examination

The preferred study for the evaluation of elbow trauma is conventional radiography. Radiographic examination requires the acquisition 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.

On radiographs, an anterior humeral line is parallel to the anterior cortex of the humerus. This line should intersect the distal, middle third of the capitellum. Displacement of this relationship suggests the presence of subtle supracondylar fractures.

The radiocapitellar line extends through the axis of the radial head and neck. This line should intersect the midcapitellum on all radiographic views.

An anterior fat pad displacement, the radiographic sail sign, may be present. The anterior fat pad is normally identified 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.

Posterior fat pad displacement may be observed. The posterior fat pad is not normally present, and its visualization is always abnormal. This finding also prompts further investigation for fractures.

When a radial head, a coronoid process, or a capitellar injury 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.

DIFFERENTIALS

Section 3 of 10  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Angiography
• Intervention
• Multimedia
• References

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.)

RADIOGRAPH

Section 4 of 10  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Angiography
• Intervention
• Multimedia
• References

Findings

Elbow dislocations

Adult elbow dislocations are classified by the direction of displacement and 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.

Complex elbow dislocations have associated fractures that compromise joint stability. Fractures of the radial head and coronoid process are the most commonly associated fractures.

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. Associated injuries occur in 10-15% of cases, which include the shoulder, distal radius, or ulna and carpal bones (Hildebrand, 1999).

The Essex-Lopresti fracture-dislocation consists of a comminuted radial head fracture and a distal radioulnar joint dislocation.

Table 1 summarizes the Bado classification system for Monteggia fracture-dislocations.

Table 1. Bado Classification of Monteggia Fracture-Dislocation

*Source: Resnick, 1992.

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 with relation to the distal humerus with or without evident fracture lines.

Elbow fractures

Elbow fractures are classified into 3 categories: (1) distal humerus fractures, (2) fractures of the proximal radius, and (3) fractures of the proximal ulna.

Table 2. Muller Classification of Distal Humerus Fractures

Supracondylar fractures

Supracondylar fractures are the most common elbow fractures in pediatric patients. Typically, patients are aged 3-10 years. In the immature skeleton, the collateral ligaments and joint capsule have greater strength compared with that of 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 the displacement and the cortical integrity. Also, because the immature elbow has developing physes, Salter-Harris fractures may occur.

Salter-Harris type I supracondylar fractures are important because elbow dislocations may be confused for these fractures. These fractures occur most frequently in infants and toddlers. The Salter Harris type I fracture affects only the physis, separating 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.

Salter-Harris type I supracondylar fracture should be distinguished from an elbow dislocation 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 it maintains its relative position to the radial head. 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.

For the true supracondylar fractures, the mechanism of injury is extension (eg, FOOSH with the elbow in full extension) or flexion (eg, direct impact to a flexed elbow). The preferred study is AP and lateral radiography, and 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. Treatment is difficult, because the amount of bone available for proper union is limited; the patient should be referred to an orthopedist. The mechanism of injury is a FOOSH. The preferred study is AP and lateral radiography and CT to assess the position of comminuted fragments. On the images, the fracture extends through the condyles proximal to the articular surface.

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 in which a force causes the olecranon to impact the articular surface of the humerus, causing the end to split. The preferred study is AP and lateral radiography; CT can be used to guide in surgical intervention. On the images, a fracture is present between condyles, and the condyles are separated from the humeral shaft. Treatment is open reduction with 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 lateral part of elbow in 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. X-ray findings include a widened intercondylar distance with lateral fractures; a fragment is commonly posteriorly and inferiorly displaced. With medial fractures, the fragment is commonly anteriorly and inferiorly displace compared with the normal position. 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.

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 an 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.

Radial head fractures

Treatment is guided by the degree of displacement and any intra-articular involvement.

Mason fractures

Mason fractures are classified into 4 types, as shown in Table 3.

Table 3. Mason Classification of Fractures

The mechanism of injury is a FOOSH that causes an impact between the radial head and the capitellum. The preferred study is lateral radiography of the anterior aspect of radial head and the radial head and capitellum to evaluate the posterior aspect of 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 a 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 detectable fractures are not present. The authors recommend conservative treatment and repeat plain radiography in 7-10 days in patients with these findings. 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, 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.

CT SCAN

Section 5 of 10  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Angiography
• Intervention
• Multimedia
• References

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.

MRI

Section 6 of 10  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Angiography
• Intervention
• Multimedia
• References

Findings

MRI has a limited role in the acute setting. In the subacute setting, MRI is invaluable in assessing the collateral ligaments; common extensor and flexor tendon originations; articular cartilage; and, to a lesser extent, occult fractures.

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 have a role in the assessment of acute vascular injury in the elbow.

ANGIOGRAPHY

Section 7 of 10  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Angiography
• Intervention
• Multimedia
• References

Findings

Arteriography is rarely indicated in the absence of definite signs of arterial injury such as 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.

INTERVENTION

Section 8 of 10  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Angiography
• Intervention
• Multimedia
• References

See the discussions for the various fractures in Radiograph.

Medical/Legal Pitfalls

• The following pearls should help to limit the number of missed cases:
• • On plain radiographs, look for the presence of the fat pad sign. A posterior fat pad sign is always abnormal, and underlying bony or ligamentous injury should be investigated.
  • The radial head–capitellar view is a useful adjunct in assessing fractures in the posterior half of the radial head, coronoid process, and capitellum.
  • Look for associated fractures on postreduction radiographs of elbow dislocations. Missed coronoid process fractures may lead to recurrent subluxation or dislocation.
  • In each case of an ulnar fracture, look for associated radial head dislocations (ie, Monteggia fracture-dislocations). Conversely, in cases of radial dislocations, look for an associated ulnar fracture.
  • A painful posttraumatic elbow with negative plain radiographic findings warrants conservative treatment, and follow-up radiographs, including repeat radial head–capitellar views, should be obtained in 7-10 days.

See also the Medscape topic Medical Malpractice and Legal Issues.

MULTIMEDIA

Section 9 of 10  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Angiography
• Intervention
• Multimedia
• References

Media file 1:  Elbow, fractures and dislocations. Anteroposterior (AP) radiograph of the elbow demonstrates the normal anatomy.
	View Full Size Image
Media type:  X-RAY

Media file 2:  Elbow, fractures and dislocations. Lateral radiograph of the elbow demonstrates the normal anatomy.
	View Full Size Image
Media type:  X-RAY

Media file 3:  Elbow, fractures and dislocations. Oblique view of the elbow demonstrates the normal anatomy.
	View Full Size Image
Media type:  X-RAY

Media file 4:  Elbow, fractures and dislocations. Radial head–capitellar view shows the normal anatomy. This view is used to assess occult fractures of the posterior half of the radial head, coronoid process, and capitellum.
	View Full Size Image
Media type:  CT

Media file 5:  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.
	View Full Size Image
Media type:  X-RAY

Media file 6:  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.
	View Full Size Image
Media type:  X-RAY

Media file 7:  Elbow, fractures and dislocations. Lateral view of the forearm demonstrates a posterior dislocation of the radius and ulna in relation to the distal humerus.
	View Full Size Image
Media type:  X-RAY

Media file 8:  Elbow, fractures and dislocations. Anteroposterior (AP) view of the elbow demonstrates a posterior-medial fracture-dislocation of the elbow.
	View Full Size Image
Media type:  X-RAY

Media file 9:  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.
	View Full Size Image
Media type:  X-RAY

Media file 10:  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.
	View Full Size Image
Media type:  X-RAY

Media file 11:  Elbow, fractures and dislocations. Lateral view of the elbow demonstrates the posterior fat pad, the sail sign, and the comminuted radial head fracture.
	View Full Size Image
Media type:  X-RAY

Media file 12:  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.
	View Full Size Image
Media type:  X-RAY

Media file 13:  Elbow, fractures and dislocations. Lateral radiograph of the elbow demonstrates a superiorly displaced fracture of the capitellum.
	View Full Size Image
Media type:  X-RAY

Media file 14:  Elbow, fractures and dislocations. Lateral view of the elbow demonstrates a displaced olecranon fracture.
	View Full Size Image
Media type:  X-RAY

Media file 15:  Elbow, fractures and dislocations. Lateral view of the elbow demonstrates a displaced radial neck fracture.
	View Full Size Image
Media type:  X-RAY

Media file 16:  Elbow, fractures and dislocations. Anteroposterior (AP) radiograph of the elbow demonstrates a T-type condylar fracture.
	View Full Size Image
Media type:  X-RAY

Media file 17:  Elbow, fractures and dislocations. Lateral radiograph of the elbow demonstrates a comminuted supracondylar fracture.
	View Full Size Image
Media type:  X-RAY

Media file 18:  Elbow, fractures and dislocations. Axial CT scan of the elbow demonstrates a displaced capitellar fracture. This image was obtained for surgical planning.
	View Full Size Image
Media type:  CT

Media file 19:  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.
	View Full Size Image
Media type:  MRI

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Angiography
• Intervention
• Multimedia
• References

• Della-Giustina K, Della-Giustina DA. Emergency department evaluation and treatment of pediatric orthopedic injuries. Emerg Med Clin North Am. Nov 1999;17(4):895-922, vii. [Medline].
• Greenspan A, Norman A. The radial head, capitellum view: useful technique in elbow trauma. AJR Am J Roentgenol. Jun 1982;138(6):1186-8. [Medline].
• Greenspan A. Upper limb I: shoulder girdle and elbow. In: Orthopedic Radiology: A Practical Approach. 1999.
• Hildebrand KA, Patterson SD, King GJ. Acute elbow dislocations: simple and complex. Orthop Clin North Am. Jan 1999;30(1):63-79. [Medline].
• Lins RE, Simovitch RW, Waters PM. Pediatric elbow trauma. Orthop Clin North Am. Jan 1999;30(1):119-32. [Medline].
• Mehdian H, McKee MD. Fractures of capitellum and trochlea. Orthop Clin North Am. Jan 2000;31(1):115-27. [Medline].
• Modrall JG, Weaver FA, Yellin AE. Diagnosis and management of penetrating vascular trauma and the injured extremity. Emerg Med Clin North Am. Feb 1998;16(1):129-44. [Medline].
• Perron AD, Brady WJ, Sing RF. Orthopedic pitfalls in the ED: Vascular injury associated with knee dislocation. Am J Emerg Med. Nov 2001;19(7):583-8. [Medline].
• Perron AD, Miller MD, Brady WJ. Orthopedic pitfalls in the ED: pediatric growth plate injuries. Am J Emerg Med. Jan 2002;20(1):50-4. [Medline].
• Pitt MJ, Speer DP. Imaging of the elbow with an emphasis on trauma. Radiol Clin North Am. Mar 1990;28(2):293-305. [Medline].
• Resnick D. Physical injury: extraspinal sites. In: Diagnosis of Bone and Joint Disorders. 3rd ed. 1992.
• Rogers LF. Radiology of Skeletal Trauma. 2nd ed. 1992.
• Rosen P. Humerus and elbow. In: Emergency Medicine: Concepts and Clinical Practice. 4th ed. 1998.
• Villarin LA Jr, Belk KE, Freid R. Emergency department evaluation and treatment of elbow and forearm injuries. Emerg Med Clin North Am. Nov 1999;17(4):843-58, vi. [Medline].

Article Last Updated: Jul 19, 2004