Metacarpal-Phalangeal Dislocation

Aka: Metacarpal-Phalangeal Dislocation, MCP Dislocation, Finger Dislocation at Metacarpal-Phalangeal Joint, Thumb MCP Dislocation

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II. Epidemiology

  1. MCP Dislocation is a rare injury
  2. Most commonly affects thumb or index fingers

III. Mechanism

  1. Injury is typically due to a direct blow to the finger with secondary hyperextension
  2. Dislocation at MCP joint is most often at thumb
  3. Dorsal MCP Dislocation is most common
    1. However volar and lateral dislocations may also occur

IV. Types of Metacarpal-phalangeal (MCP) Dislocation

  1. Simple Dislocation
    1. Dislocation without interposed soft tissue
  2. Complex Dislocation
    1. Soft tissue interposed in the joint
    2. Requires surgical reduction

V. Management: Simple Dislocation

  1. Precautions
    1. Avoid reduction by traction (distraction)
      1. Risk of converting a simple to complex dislocation (interposed tissue) requiring surgical reduction
  2. Anesthesia
    1. See Hand and Wrist Regional Anesthesia
  3. Reduction (dorsal dislocation)
    1. Flex wrist
    2. Hyperextend dislocated joint as far as possible
    3. Push base of proximal phalanx distally
    4. Bring joint back into flexion while pushing base
    5. Avoid simple traction (risk of complex dislocation)
  4. Post-reduction joint assessment
    1. Assess joint range of motion
    2. Assess collateral ligaments with MCP flexed
    3. Imaging to assess joint congruity
  5. Immobilization for 3 weeks
    1. Early range of motion and strengthening in uncomplicated dislocations
    2. Direction of dislocation
      1. Dorsal dislocation or Lateral Dislocation
        1. orthoFingerDorsalExtensionBlockSplint.jpg
        2. Splint at 30 degrees of flexion at MCP with Dorsal Extension Block Splint for 7-10 days
        3. Then buddy tape for 2 to 3 weeks and range of motion Exercises
      2. Volar dislocation
        1. Splint to maintain extension
        2. Discuss and refer to local orthopedic consultants
    3. Finger involved
      1. Thumb MCP Dislocation: Cast thumb for 3 weeks
      2. Finger MCP Dislocation: Buddy tape for 3 weeks
  6. Referral for Lateral Dislocations for any of the following findings
    1. Delayed presentation >2 weeks
    2. XRay findings involve >20% of joint surface
    3. Displacement >2 mm
    4. Instability (typically of radial collateral ligament with ulnar tilt)

VI. Management: Complex Dislocation

  1. Reduction usually impossible by closed method
    1. Joint does not snap back into place
    2. Joint does not feel reduced
    3. Reduction prevented by soft tissue in joint
  2. Surgery usually needed
    1. Open reduction and internal fixation (ORIF)

VII. Complications

  1. Volar Plate Injury (dorsal MCP Dislocation)

VIII. References

  1. Broder (2025) Am Fam Physician 39(9): 22-4
  2. Childress (2022) Am Fam Physician 105(6): 631-9 [PubMed]

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