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  • Thumb ulnar collateral ligament (UCL) tear
  • Thumb UCL sprain
  • Skier’s thumb
  • Breakdancer’s thumb

  • 842.12 Sprains and strains of metacarpophalangeal (joint) of hand

  • S63.659 A Sprain of metacarpophalangeal joint of unspecified finger, initial encounter
  • S63.649 A Sprain of metacarpophalangeal joint of unspecified thumb, initial encounter


Essentials of Diagnosis

  • Gamekeeper’s thumb is ligamentous disruption of the UCL of the first MCP joint due to acute or repeated valgus stress to the thumb.
  • Presents as instability and/or pain with valgus forces to the thumb or pain and weakness with opposition or pinching.
  • Tenderness or swelling may be present at medial aspect of thumb.
  • Valgus stress to the UCL of the first MCP will result in asymmetric laxity compared to uninvolved side or lack of an end point.

General Considerations

  • Injury can be either acute or chronic and is common in athletics (especially skiing and football).
  • Injury involves valgus force to the proximal phalanx of the thumb.
  • Injury can also involve an avulsion fracture of the base of the proximal phalanx, which is termed “gamekeeper’s fracture.”
  • Plain film radiographs are beneficial to rule out fracture.
  • Manage surgically or non-surgically depending upon severity of signs and symptoms and orthopedic physician recommendations


  • Common in athletes, typically involving a fall (football), impact from a ball (basketball), or repeated stress (skiing)
  • Seen in fowl hunters

Signs and Symptoms

  • Pain over medial MCP joint
  • Palpable tenderness and possible swelling over medial MCP joint line/UCL of thumb
  • Instability and/or pain with valgus stress to MCP of thumb
  • Weakness with pinching or opposition
  • Repeat subluxation of the MCP resulting in medial angulation of the proximal phalanx with valgus stress or force

Functional Limitations

  • Difficulty and/or pain when grasping dishes, utensils, or drinking cups due to pain and weakness
  • Difficulty and/or pain when grasping and turning steering wheel
  • Difficulty and/or pain when turning doorknob

Possible Contributing Causes

  • Participation in activities or sporting events that involve repeated valgus stress to proximal phalanx in thumb
  • Participation in contact sports
  • Generalized ligamentous laxity

Differential Diagnosis

  • Gamekeeper’s fracture
  • Fracture of the base of the first metacarpal bone (Bennett’s fracture)
  • Distal metacarpal fracture
  • Proximal phalanx fracture
  • Extensor tendon rupture (boutonnière deformity)

Laboratory Tests


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