What Is A Sprained Thumb?

A sprained thumb occurs when the ligaments supporting the thumb stretch or tear. This often occurs when the thumb is bent backwards away from the hand. Most thumb sprains involve the ulnar collateral ligament, or UCL. When the UCL tears, it causes pain and a feeling of instability in the digit. As a result, a patient may find it difficult to grasp between the thumb and index finger.

Like other sprains, a thumb sprain is graded between 1-3.

Grade 1: Ligaments are stretched, but not torn, and the pain is mild.

Grade 2: Ligaments are partially torn and there is some loss of function. Pain is moderate.

Grade 3: Ligament is completely torn and removed from the bone. Pain is severe and the condition often requires surgical care.