• Clinical science

Finger injuries

Abstract

Finger injuries are very common and because there are many different possible injuries, only some of the more common flexor and extensor tendon as well as ligament injuries will be covered here. Injury is typically caused by lacerations (work place injury, road traffic accidents) or blunt force (e.g., ball sports, falling). For instance, forced extension of the distal interphalangeal joint (DIP) can damage the flexor digitorum profundus (FDP) tendon and lead to a loss of DIP flexion (Jersey finger). Forced flexion of the DIP causes extensor digitorum (ED) tendon injury, which results in a loss of DIP extension (mallet finger). Rupture/slippage of the central band of the ED tendon is primarily due to laceration or blunt injury and results in a hyperextension of the DIP with flexion of the PIP (Boutonniere deformity). Sudden forced hyperextension and abduction of the metacarpophalangeal joint (MCP) of the thumb can tear the ulnar collateral ligament (UCL) and cause laxity (Gamekeeper's thumb). While all flexor tendon injuries need to be surgically repaired, most extensor tendon and some ligament injuries can be managed conservatively with splints. Complete laceration or no response to conservative therapy are indications for surgical repair. Postoperative complications of tendon or ligament injuries include adhesions, joint contractures, and chronic joint deformities (e.g., swan-neck deformity, chronic mallet finger). Early recognition and treatment of injuries and their complications is necessary to prevent permanent disability.

Diagnostics

  • Physical examination (see "clinical features" below) [1]
  • X-ray: three views are taken (posterior-anterior, oblique, and lateral) to identify coexistent fractures[2]
  • Ultrasound: can detect complete lacerations [3]
  • MRI: provides accurate description of the extent of tendon or ligament injury[4]

Differential diagnoses

Differential diagnoses of finger injuries

Affected tendon(s) or ligament(s) Condition Mechanism of injury Clinical features Treatment Possible complications
Flexor digitorum profundus tendon Jersey finger
  • Sudden hyperextension of a flexed DIP (forced extension) [4][5]
  • Avulsion injury/rupture of the FDP tendon from its point of insertion[5] There may also be an avulsion fracture of the base of the distal phalanx.
  • Pain, swelling of the DIP (palmar aspect)[5]
  • Loss of DIP flexion → the affected finger does not flex when making a fist [4][5]
  • Always surgical [6][5]
    • Primary repair [1].
    • Tendon graft
Extensor digitorum tendon Mallet finger
  • Sudden hyperflexion of the DIP (forced flexion) → avulsion/rupture of the distal portion of the ED tendon from the distal phalanx[1][4][8]
  • May be associated with an avulsion fracture of the distal phalanx[8]
  • Less commonly: laceration/crush injury of the distal phalanx
  • Loss of extension of the DIP [4]
  • Conservative: splint in extension position [1][4]
  • Surgical repair for:[1]
    • Displaced fracture
    • ≥ 45-degree extension deficit
Central band of extensor digitorum tendon Boutonniere deformity
  • Slippage/disruption of the central band of the ED [9][10]
  • Hyperextension of the DIP with flexion of the PIP[10]
  • Conservative: Splint the finger in extension[9] position for 6 weeks
  • Surgical repair: for chronic Boutonniere deformity (e.g., repair of the central band, tenotomy, arthrodesis)[9]

Ulnar collateral ligament (UCL) of the thumb[11]

Gamekeeper's thumb (Skier's thumb)
  • Hyperextension and sudden forced abduction of the MCP of the thumb (e.g., falling on the thumb; skiing injury) → UCL tears
  • Pain and swelling of the MCP joint of the thumb
  • Laxity of the thumb MCP joint
  • Weak pinch grip
  • Conservative: Thumb spica (splinting)
  • Surgical repair: for persistent deformities (e.g.: repair of the torn UCL; MCP joint fusion)[12]

The differential diagnoses listed here are not exhaustive.