Wiki Ulnar Collateral Ligament Sprain of Thumb ICD-10?

I walked this through the encoder. If you code for the ulnar collateral ligament sprain, it points you to either elbow or traumatic rupture. Using thumb sprain, I came up with S63.682A Other sprain of left thumb, initial encounter. That's a weird one.
A "Sprain" of the Ulnar Collateral Ligament of the thumb as an acute or subacute injury (current), as opposed to a chronic condition, often goes by the name of Game Keeper's Thumb &/or Skier's Thumb. As a current injury, this would be S63.64 _ _ (Sprain of the Metacarpophalangeal Joint of the thumb, but without specifying radial or ulnar collateral ligaments). However, if this is an old sprain/ligamentous injury, i.e. a chronic condition, then it would come under M24.2: Disorder of the Ligaments (Chronic Instability secondary to old ligamentous injury). The 5th Character would be 4 for hand, and the 6th Character would be for laterality.

Hope this helps.

Respectfully submitted, Alan Pechacek, M.D.