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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


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

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


  • 4D: Impaired Joint Mobility, Motor Function, Muscle Performance, and ROM Associated with Connective Tissue Dysfunction


The patient is a 22-year-old competitive downhill skier who injured herself during a fall on the slopes. She reports that her thumb was forced outward by the ski pole as she fell. She was taken to the emergency complaining of pain and inability to use the thumb. It was determined that a partial rupture of the UCL of her L thumb at its proximal insertion had occurred, and that conservative treatment was indicated. She was provided with a cast to the hand which held the thumb midway between radial and palmar abduction, and in approximately 5 degrees MP flexion, with the IP joint free. She presents to the clinic 3 weeks later.

The patient has focal swelling and tenderness at the medial aspect of the first metacarpophalangeal (MCP) joint. She is having difficulty with grasping kitchen utensils and drinking cups and difficulty turning doorknobs due to pain and weakness of the thumb. The patient presents with grade II laxity during a valgus stress test at 30 degrees of the first MCP joint.



  • Injury involving the UCL of the 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

FIGURE 174-1

Gamekeeper’s thumb. Laxity of 30 to 40 degrees more than the uninjured thumb measured in neutral and 30 degrees of flexion are strongly suggestive of a complete ulnar collateral ligament tear. There is no “endpoint” to the radial deviation of the phalanx. (Used with permission from Brunicardi FC, Anderson DK, Billar TR, et al. Schwartz’s Principles of Surgery, 8th ed. © 2005 McGraw-Hill, New York, NY.)

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 the thumb.

  • Valgus stress to the UCL of the first MCP joint will result in asymmetric laxity compared ...

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