Mallet finger

Background

Possible mechanisms of injury from axial force applied to the tip of a straight digit (black arrows) causing: (top) DIP joint hyperextension (white upper arrow) and fracture, or (bottom) DIP hyperflexion (lower white arrow) and tendon lesion.

Finger in maximum extension

Mallet finger without fracture

Mallet finger with fracture at the insertion of the extensor tendon

• Rupture of extensor tendon in area of distal phalanx distal to DIP joint
  • May be accompanied by avulsion fracture
• Caused by forced flexion of extended DIP joint
• If untreated, leads to swan neck deformity

Clinical Features

• DIP joint flexed to 40°, unable to fully extend

Differential Diagnosis

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

• Clinical diagnosis
• Consider finger x-ray (PA and lateral) to evaluate for avulsion fracture

Management

• Splint DIP joint in continuous slight hyperextension x 6 wk
• Splinting of the PIP joint is not necessary and should be avoided
  • Inadvertently splinting PIP for 6 weeks results in collateral ligamentous overgrowth and functional disability
• Give an extra splint

Special Mallet finger splint (if available)

Disposition

• Discharge with hand surgery follow-up in 7-10 days

See Also

• Hand and finger diagnoses