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Condition/Disorder Synonyms

  • Thumb ulnar collateral ligament (UCL) tear

  • Thumb UCL sprain

  • Skier's thumb

  • Breakdancer's thumb

ICD-9-CM Code

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

ICD-10-CM Codes

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

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

Preferred Practice Pattern

Key Features


  • Injury involving the UCL of the metacarpophalangeal (MCP) joint in the first ray (thumb)

  • Acute or repeated forceful abduction (valgus force) to the proximal phalanx results in ligamentous disruption.

  • Instability of the MCP joint

  • Forced extension or abduction of the proximal phalanx of the thumb

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

Clinical Findings

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


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