Dislocations of the Elbow are covered under this heading. Only cases where both bones of the forearm are displaced on the humerus are included here; single bone displacements will be discussed later. The surgical anatomy includes the hinge-type articulation between the humerus and ulna, and the ball-and-socket type between the humerus and radius head. Stability depends largely on the lateral ligaments and humero-ulnar articulation.
The overwhelming majority of elbow dislocations are backward types caused by forced hyperextension. If bones prove stronger than ligaments, fractures occur; otherwise, luxations result. Common complications include extensive tearing of ligaments, especially laterals, and fractures like epitrochlea avulsion or coronoid process breakage. The periosteum is often stripped from the posterior humerus.
Symptoms involve pain, tenderness, loss of function, restricted mobility, swelling, and disturbed prominence relations. Posterior dislocations are most common, with the forearm in a position between complete extension and semiflexion. Pain increases on movement due to muscle spasm and joint disturbance. The olecranon is prominently raised above normal level.
Lateral dislocations can be internal or external, varying degrees of displacement and rotation. Forward dislocation is rare but possible after olecranon fracture. Divergent dislocations are extremely rare, usually resulting from severe trauma. Nerve and vessel injuries are uncommon except in compound luxations. <Callout type="important" title="Critical to Recognize">Posterior dislocations are the most common and should be identified by the prominent triceps tendon and empty sigmoid cavity.</Callout>
Diagnosis involves recognizing bony lesions, complicating fractures, and soft tissue injuries. Fractures of the lower humerus can mimic luxations but lack an empty sigmoid cavity.
Key Takeaways
- Posterior dislocation is the most common type and involves significant pain, restricted movement, and prominent triceps tendon.
- Lateral stability of the elbow is crucial but often impaired in luxations.
- Complications include ligament tearing, fractures like epitrochlea avulsion or coronoid process breakage.
Practical Tips
- Identify posterior dislocation by checking for an empty sigmoid cavity and prominent triceps tendon.
- Use palpation to determine the position of bony prominences in diagnosing lateral displacements.
Warnings & Risks
- Do not confuse elbow fractures with luxations; look for an empty sigmoid cavity in suspected luxations.
- Be cautious of nerve injuries, especially median and musculospiral nerves, which may be affected by the lower humerus projection.
Modern Application
While this chapter's diagnostic techniques are still relevant today, modern imaging technologies like X-rays and MRI provide more accurate confirmation. Understanding these historical methods enhances our ability to assess and treat elbow injuries in remote or resource-limited settings.
Frequently Asked Questions
Q: What is the most common type of dislocation at the elbow?
The most common type of dislocation at the elbow is the posterior variety, characterized by forced hyperextension causing displacement of both bones of the forearm on the humerus.
Q: How can one distinguish between a fracture and a luxation in the lower end of the humerus?
To differentiate between a fracture and a luxation at the lower end of the humerus, check for an empty sigmoid cavity. If present, it indicates a dislocation rather than a fracture.
Q: What are common complications in elbow dislocations?
Common complications include extensive tearing of ligaments, especially laterals, and fractures such as epitrochlea avulsion or coronoid process breakage. The periosteum is often stripped from the posterior humerus.