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.

• May be accompanied by avulsion fracture
• Caused by forced flexion of extended DIP joint
• If untreated, leads to swan neck deformity

Clinical Features

Finger in maximum extension

• Rupture of extensor tendon in area of distal phalanx distal to DIP joint
• 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

Mallet finger without fracture

Mallet finger with fracture at the insertion of the extensor tendon

• 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