Metacarpophalangeal dislocation (finger)

Background

Distal interphalangeal dislocation (DIP), proximal interphalangeal dislocation (PIP), and metacarpophalangeal dislocation (MCP) joints of the finger shown.

Volar/anterior finger anatomy.

Lateral finger anatomy.

• Also known as the MCP joint
• Usually forces that rupture volar plate cause dorsal dislocation

Hand Anatomy

• Volar = anterior = dorsal
• Dorsal = posterior = palmar

Clinical Features

• Mechanism: hyperextension
• Finger pain/deformity

Differential Diagnosis

Hand and finger dislocations

• Finger dislocations
  • Distal interphalangeal dislocation (finger) (DIP)
  • Proximal interphalangeal dislocation (finger) (PIP)
  • Metacarpophalangeal dislocation (finger) (MCP)
• Thumb dislocations
  • Interphalangeal dislocation (thumb) (IP)
  • Metacarpophalangeal dislocation (thumb) (MCP)
• Hand dislocations
  • Carpometacarpal dislocation

Hand and finger injuries

• Distal finger
  • Finger amputation
  • Fingertip laceration
  • Nail avulsion
  • Nailbed laceration
  • Subungual hematoma
• Other finger/thumb
  • Boutonniere deformity
  • Mallet finger
    • Swan neck deformity
  • Jammed finger
  • Jersey finger
  • Trigger finger
  • Ring avulsion injury
  • De Quervain tenosynovitis
  • Infiltrative tenosynovitis
  • Metacarpophalangeal ulnar ligament rupture (Gamekeeper's thumb)
• Hand
  • Dupuytren contracture
• Wrist
  • Drummer's wrist
  • Ganglion cyst
  • Lunotriquetral ligament instability
  • Scaphoid fracture
  • Extensor digitorum tenosynovitis
  • Compressive neuropathy ("bracelet syndrome")
  • Intersection syndrome
  • Snapping Extensor Carpi Ulnaris
  • Vaughn Jackson syndrome
• General
  • Hand and finger dislocations
  • Hand and finger fractures
  • Hand and finger infections
  • Gout and pseudogout
  • Hand and finger tendon injuries
  • High-pressure injection injury
  • Osteoarthritis
  • Rheumatoid arthritis
  • Ring removal

Evaluation

Types

• Simple: subluxation
  • Joint appears hyperextended to 60-90 deg
• Complex: dislocation
  • MCP joint is in moderate hyperextension with metacarpal head prominent in palm
  • Volar plate is interposed in MCP joint space
  • X-ray may show seasamoid within joint space (pathognomonic)
    • Closed reduction is not possible

Management

Reduction

• Traction alone may convert simple MCP dislocation may convert it to a complex dislocation
• Dorsal dislocation
  • Flex the wrist to relax the flexor tendon
  • Hyperextend the joint
  • Apply pressure over dorsum of proximal phalanx in distal and volar direction
• Volar dislocation
  • Rare, will likely need open reduction
  • If attempting closed reduction, push finger into the MCP joint and then hyperflex joint
  • After hyperflexing, pull traction and extend finger, using thumbs to guide proximal finger into place

Splinting

• Splint with MCP joint in flexion
• Refer to hand surgeon within 2 weeks

Disposition

• Outpatient management

See Also

• Hand and finger dislocations