Elbow Dislocations: Types, Classification, Symptoms, and Treatment

What are the different types of elbow dislocations?

Elbow dislocations are primarily classified by the direction of displacement of the ulna and radius relative to the humerus, most commonly posterior, but also anterior, medial, lateral, or divergent. Further classification distinguishes between simple dislocations (no associated fracture) and complex dislocations (involving fractures), alongside considerations such as open/closed and acute/chronic presentations.

Understanding Elbow Anatomy and Stability

The elbow joint, a complex hinge joint, is formed by the articulation of three bones: the humerus (upper arm bone), and the radius and ulna (forearm bones). Its primary function is to allow flexion and extension, with the forearm bones also enabling pronation and supination through the radioulnar joint.

Joint stability is provided by a combination of bony congruity (especially the olecranon and coronoid processes of the ulna articulating with the humerus), and robust ligamentous structures:

• Medial (Ulnar) Collateral Ligament (MCL): Crucial for resisting valgus stress (force applied to the outside of the elbow).
• Lateral (Radial) Collateral Ligament (LCL) Complex: Resists varus stress (force applied to the inside of the elbow) and posterolateral rotatory instability.
• Annular Ligament: Encircles the radial head, holding it against the ulna.

Despite this inherent stability, high-energy trauma can overcome these stabilizing structures, leading to dislocation.

What is an Elbow Dislocation?

An elbow dislocation occurs when the articulating surfaces of the ulna and radius completely lose contact with the articulating surface of the humerus. This is a severe injury, typically resulting from a fall onto an outstretched hand (FOOSH) with the elbow in slight flexion, leading to a combination of axial compression, valgus stress, and external rotation.

Symptoms typically include:

• Severe pain and swelling.
• Visible deformity of the elbow.
• Inability to move the arm.
• Potential numbness or tingling if nerves are affected.

Classification of Elbow Dislocations

Elbow dislocations are categorized based on several factors, primarily the direction of displacement and the presence of associated injuries.

Primary Classification: Direction of Displacement

This classification describes how the ulna and radius displace relative to the distal humerus.

• Posterior Dislocation:

  • Description: This is the most common type, accounting for over 90% of all elbow dislocations. The forearm bones (ulna and radius) are displaced posteriorly (backward) relative to the humerus.
  • Mechanism: Typically results from a FOOSH injury with the elbow in extension or slight flexion, often combined with a valgus (outward) or varus (inward) force.
  • Associated Injuries: Often involves tears of the MCL and LCL complex. Fractures of the coronoid process, radial head, or medial epicondyle are common, making it a complex dislocation.

• Anterior Dislocation:

  • Description: Less common than posterior dislocations. The forearm bones are displaced anteriorly (forward) relative to the humerus.
  • Mechanism: Usually caused by a direct blow to the posterior aspect of the elbow, or a hyperextension injury with the forearm fixed.
  • Associated Injuries: Can involve olecranon fracture, making it a complex dislocation. Risk of brachial artery or median nerve injury is higher.

• Medial or Lateral Dislocation:

  • Description: The forearm bones are displaced medially (inward) or laterally (outward) relative to the humerus. These are relatively rare as isolated injuries.
  • Mechanism: Often involve significant varus or valgus stress, respectively, with associated rotatory forces.
  • Associated Injuries: Frequently accompanied by extensive soft tissue damage and potentially fractures of the radial head or epicondyles.

• Divergent Dislocation:

  • Description: A rare and severe injury where the ulna and radius not only dislocate from the humerus but also separate from each other, with the radial head displacing laterally and the ulna displacing medially or posteriorly.
  • Mechanism: High-energy trauma, often involving a combination of forces that disrupt both the humeroulnar and radioulnar joints.
  • Associated Injuries: Extensive ligamentous disruption (MCL, LCL, interosseous membrane) and often associated with fractures.

Secondary Classification: Severity and Complexity

This classification distinguishes dislocations based on the presence of concomitant fractures.

• Simple Dislocation:

  • Description: A dislocation without any associated fracture of the bones forming the elbow joint.
  • Prognosis: Generally has a better prognosis for recovery with proper reduction and rehabilitation, though ligamentous damage is always present.

• Complex Dislocation:

  • Description: A dislocation accompanied by one or more fractures around the elbow joint. These fractures can involve the radial head, coronoid process of the ulna, olecranon, or the humeral epicondyles.
  • Prognosis: Typically more severe, requiring more intricate management, potentially surgical intervention, and often carries a higher risk of complications such as stiffness, instability, or post-traumatic arthritis.

Other Important Classifications

• Open vs. Closed:
  • Open: The skin is broken, and the bone may be exposed, increasing the risk of infection.
  • Closed: The skin remains intact.
• Acute vs. Chronic:
  • Acute: Recently occurred (within hours or days).
  • Chronic: Persistent dislocation for weeks or months, often due to missed diagnosis or inadequate initial treatment.
• Isolated vs. Associated Injuries:
  • Consideration of nerve damage (ulnar, median, radial nerves), vascular injury (brachial artery), or compartment syndrome.

Associated Injuries and Complications

Regardless of the type, elbow dislocations are often accompanied by other injuries and can lead to long-term complications if not managed appropriately.

• Ligamentous Instability: Tears of the MCL and LCL complex are almost universal.
• Fractures: Radial head, coronoid process, olecranon, and epicondyle fractures are common.
• Nerve Injuries: The ulnar, median, or radial nerves can be stretched or contused.
• Vascular Injuries: The brachial artery, which supplies blood to the forearm and hand, can be damaged, leading to serious complications.
• Stiffness: A common complication, often requiring extensive physical therapy.
• Heterotopic Ossification: Abnormal bone formation in soft tissues around the joint.
• Recurrent Instability: The elbow can become prone to repeat dislocations.

Diagnosis and Treatment Principles

Diagnosis typically involves a thorough clinical examination, assessing deformity, pain, and neurovascular status, followed by imaging studies like X-rays to confirm the dislocation and identify any associated fractures. CT scans or MRI may be used to further assess complex fractures or soft tissue damage.

Treatment generally involves:

1. Reduction: Manually repositioning the bones back into their correct anatomical alignment.
2. Immobilization: Short-term splinting or casting to allow initial healing of soft tissues.
3. Rehabilitation: A structured physical therapy program to restore range of motion, strength, and stability.
4. Surgical Intervention: May be necessary for complex dislocations involving significant fractures, persistent instability after reduction, or severe ligamentous tears.

Importance of Professional Medical Evaluation

Given the potential for severe associated injuries and long-term complications, any suspected elbow dislocation requires immediate and comprehensive medical evaluation by a qualified healthcare professional. Self-diagnosis or delayed treatment can lead to chronic pain, permanent stiffness, instability, or even loss of limb function. Understanding the types of elbow dislocations underscores the complexity and the need for individualized, expert management.