A UCL tear, or ulnar collateral ligament tear, is an injury to the ligament that stabilizes the elbow joint on the inside of the arm. This ligament can be torn due to overuse, trauma, or degeneration. A UCL tear can cause pain and instability in the elbow and can result in decreased throwing velocity for athletes who participate in throwing sports. Treatment options for a UCL tear include rest, physical therapy, and in severe cases, surgery.
Initial tests after Purdy was injured in the NFC Championship loss to the Philadelphia Eagles showed a UCL injury, but the Niners were unaware of the severity. The hope was that six-week recovery would come if it wasn't torn.
Instead, Purdy will be shut down for six months as he needs to undergo surgery to repair it.
However, it looks like some still believe he should've stayed in the game and "gut it out".
Indeed, here is what Reggie Bush said about Purdy: