In adults, the elbow is the second most frequently dislocated major joint, after the shoulder. It is the most commonly dislocated joint in children.  More than 90% of all elbow dislocations are posterior dislocations. This injury entails disengagement of the coronoid process of the ulna from the trochlea of the humerus with movement posteriorly.  The mechanism of injury is typically a fall onto an outstretched hand (FOOSH) with the elbow in extension upon impact.
The patient typically presents with a shortened forearm that is held in flexion with a prominent olecranon posteriorly. Noting disruption of the tight triangular relationship of the tip of the olecranon with the distal humeral epicondyles, when comparing the injured elbow with the unaffected side, can help to confirm the diagnosis clinically.
Injured structures include the anterior and posterior bands of the medial and lateral collateral ligaments of the elbow, along with, at times, the brachialis muscle, the flexor-pronator muscle group, and articular cartilage.  The ipsilateral upper extremity should be examined for other injuries as well, particularly shoulder and wrist fractures and disruption of the distal radioulnar joint. The elbow should be inspected for crepitus, which is an indicator of fracture.
Of note, the ulnar nerve, median nerve, and brachial artery can be compromised.  Therefore, assessing distal neurovascular status is crucial to determine the need for immediate reduction. Injury to the median and ulnar nerves is typically the result of stretch, entrapment, or severance. Brachial artery injury, although possible in any type of dislocation, is frequently seen in open dislocations. Vascular compromise can be caused by brachial artery injury or compression and may be delayed in presentation as a result of hematoma formation or soft tissue swelling. Therefore, vascular integrity warrants careful monitoring even after successful reduction.
Joint reduction is indicated for any clinical or radiographic diagnosis of acute posterior elbow dislocation. Urgent joint reduction is indicated if evidence of neurovascular compromise is present.
Contraindications for joint reduction in the setting of a posterior elbow dislocation include the following:
Lack of familiarity with reduction
Injury without neurovascular compromise in any child prior to radiographic evaluation; fractures are more common than dislocations in children
Multiple prior unsuccessful attempts at reduction