The UCL is the ligament that is repaired during Tommy John surgery, which Floyd could end up having, but he won't make that decision until he is examined Monday in New York by orthopedic specialist Dr. David Altchek.
At the very least, Floyd figures to be out for a significant amount of time. If surgery is needed on his flexor muscle and/or his UCL, he likely will be lost for the season.
If surgery is the case, Floyd -- who will be a free agent after the season -- may have pitched in his final game in a White Sox uniform.
Floyd's most recent injury happened Saturday during a start against the Tampa Bay Rays when he lasted just 2 2/3 innings. He also had two separate elbow issues last season, one with his flexor muscle and another with tendinitis. Neither required surgery.
Floyd was 0-4 this season with a 5.18 ERA in five starts, all of which ended in White Sox defeats. He is 63-65 with a 4.22 ERA in seven seasons with the White Sox.
His best season came in 2008, when he posted a 3.84 ERA in 33 starts (206 1/3 innings) and won 17 games.