Also known as "Gamekeeper's thumb" or "Skier's thumb"<unk>  collateral<unk><unk> s at insertion into proximal phalanx (due to radial deviation of MCP)
If left untreated, it will causes decreased thumb adduction and inability to perform opposition.
The mechanism of injury is usually a rapid deceleration while holding onto an object (such as a ski pole)
Metacarpophalangeal ulnar ligament rupture
Distal finger
Metatarsophalangeal joint sprain
Finger amputation
Ankle syndesmosis injury
Fingertip laceration
Acromioclavicular joint injury
Nail avulsion