Terrible Triad Injury of the Elbow

What is a Terrible Triad Injury of the Elbow?

A Terrible Triad Injury of the Elbow is a severe and complex injury that involves:

• Elbow Dislocation: The elbow bones are forced out of their normal positions.
• Radial Head or Neck Fracture: The radial head or neck, part of the radius bone near the elbow, is fractured.
• Coronoid Process Fracture: The coronoid process is fractured, a triangular part of the ulna bone.

Diagnosis

• X-rays: The primary tool for diagnosing the injury. They help visualise the position of the bones and identify fractures.
• CT Scans: These are often used to get a more detailed view of the fractures, especially useful for surgical planning.

Treatment Options

• Surgical Treatment:
  • Open Reduction and Internal Fixation (ORIF): Surgical method to fix the fractures using plates, screws, or rods.
  • Radial Head Arthroplasty: Replacement of the radial head with a prosthetic implant.
  • Lateral Collateral Ligament (LCL) Reconstruction: Repairing the ligament on the outer side of the elbow.
  • Coronoid ORIF: Surgical fixation of the coronoid fracture.
  • Medial Collateral Ligament (MCL) Reconstruction: Repairing the ligament on the inner side of the elbow if necessary.

Causes and Mechanism

• Causes: Typically occurs from a high-energy impact, such as falling onto an outstretched hand with the arm extended.
• Mechanism:
  • The elbow is subjected to valgus (outward), axial (along the arm’s length), and posterolateral rotatory (twisting) forces.
  • This combination leads to dislocation and fractures, starting from the lateral side and moving medially.
  • Pathoanatomy:
    • The LCL is the first structure to fail.
    • The anterior capsule of the elbow is injured next.
    • MCL disruption can occur if the force is significant enough.

Anatomy Involved

• Radial Head:
  • Key to preventing posterolateral rotatory instability (PLRI).
  • Acts as a secondary stabilizer against valgus forces.
• Coronoid Process:
  • Provides stability to the ulnohumeral joint.
  • Prevents posterior subluxation (partial dislocation) beyond 30 degrees of flexion.
  • The fracture often includes part of the anterior capsule, which aids in repair.
• Medial Collateral Ligament (MCL):
  • Composed of three parts: anterior bundle (most important for stability), posterior bundle, and transverse ligament.
  • Essential for resisting valgus and posteromedial rotatory forces.
• Lateral Collateral Ligament (LCL):
  • Comprises four parts: lateral ulnar collateral ligament (LUCL), radial collateral ligament (RCL), annular ligament, and accessory collateral ligament.
  • Crucial for preventing posterolateral rotatory instability.
  • Often avulsed (torn off) from the lateral epicondyle during injury.

Symptoms and Examination

• Symptoms:
  • Severe pain in the elbow.
  • Clicking and locking sensation, especially when extending the elbow.
• Physical Exam:
  • May reveal instability patterns (varus or valgus).
  • The distal radial ulnar joint should be checked for Essex-Lopresti injury (a severe injury involving the radial head and the interosseous membrane).

Imaging

• Radiographs (X-rays):
  • Essential for evaluating the alignment of the ulnohumeral and radiocapitellar joints.
  • Look for coronoid fractures.
  • Both pre-reduction (before the bones are set) and post-reduction films are needed.
  • Additional wrist and forearm X-rays may be necessary.
• CT Scans:
  • Provide a detailed view of the coronoid fracture.
  • 3D imaging can help determine the exact nature of the fracture lines.

Treatment Details

Nonoperative Treatment

• Immobilization:
  • The elbow is immobilized at 90 degrees of flexion for 7-10 days.
  • Indicated in rare cases where the joints are stable, fractures are small, and early range of motion is feasible.
• Technique:
  • After a week of immobilization, gradual progression to active motion begins.
  • Initial active motion with the elbow at 90 degrees and forearm pronated, avoiding terminal extension.
  • Static progressive extension splinting at night after 4-6 weeks.
  • Strengthening exercises start after six weeks.

Operative Treatment

• Indications:
  • Required for unstable injuries with significant fractures and dislocations.
• Techniques:
  • ORIF or Radial Head Arthroplasty: Depending on the fracture type and severity.
  • LCL Reconstruction: Using suture anchors or transosseous sutures.
  • MCL Reconstruction: If instability persists after addressing other structures.
• Surgical Approach:
  • A posterior skin incision provides access to the elbow’s medial and lateral aspects.
  • This approach is more cosmetic and has a lower risk of injuring cutaneous nerves.
• Specific Techniques:
  • Radial Head ORIF: Using screws and plates if fractures are less than 40% of the articular surface.
  • Radial Head Arthroplasty: For comminuted fractures (more than three pieces).
  • Coronoid ORIF: Using sutures, suture anchors, screws, or plates.
  • LCL Repair: Reattachment with sutures or anchors at the lateral epicondyle.
  • MCL Repair: Indicated for persistent instability after other repairs.

Complications

• Instability: More common with Type I or II coronoid fractures.
• Failure of Fixation: Often seen in radial neck fractures due to poor vascular supply.
• Stiffness: Very common; early ROM exercises are crucial.
• Heterotopic Ossification: Prophylaxis may be necessary in high-risk patients.
• Post-Traumatic Arthritis Can result from initial cartilage damage or residual instability.

Prognosis

• Historically, outcomes have been poor due to:
  • Persistent instability.
  • Joint stiffness.
  • Development of arthritis.
• Early and appropriate treatment is essential for better outcomes and to minimise complications.

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