A thumb sprain is a stretch, tear, or complete rupture of one of the ligaments that connect the bones of the thumb together. This injury may happen to downhill skiers, when the ski pole straps force the thumb backward during a fall. Mallet finger occurs when a muscle that extends to the end of one of the fingers rips completely away. It leaves the last part of the finger crooked. If untreated, a mallet finger can become permanently painful and deformed.
Arthritis can develop in that finger later in life.
Jammed fingers are finger sprains caused by stretched or torn ligaments that normally hold the finger bones together. Flexor tendonitis is an overuse injury that causes irritation and pain to the muscles of the forearm. The condition is caused by constant forceful bending of the hand and fingers toward the palm, as in pitching and racquet sports. It can be treated with rest and ice. If you injure your hand, place it in a splint.