Michael Fulmer was a key member of the Cubs’ bullpen before he was struck by the injury bug late in the season.

It’s going to keep him out of the 2024 season, too.

Fulmer underwent right elbow ulnar collateral ligament (UCL) revision surgery on Wednesday and is expected to miss all of 2024. UCL revision surgery is different from Tommy John surgery, but it’s also used to correct an injured UCL. Fulmer, a free agent this offseason, underwent Tommy John surgery in 2019.

It was one of many injury updates the Cubs provided Thursday on a series of players who ended the season on the IL.

Codi Heuer, who has not pitched in a major-league game since 2021, completed the initial healing and range of motion phase of his rehab. The Cubs hope to have him begin a throwing progression in mid-November but have no timetable for his return.

Heuer, 27, underwent Tommy John surgery in 2022 just before the lockout was lifted and missed all that season. He was on a minor league rehab assignment this year at Iowa when he suffered an elbow fracture. In 15 rehab games with Iowa, Heuer had a 7.82 ERA in 12.2 innings with 15 strikeouts and a 2.05 WHIP.

He was acquired at the 2021 trade deadline along with Nick Madrigal for closer Craig Kimbrel. In 25 games with the Cubs that year, he had a 3.14 ERA and 2 saves.

Reliever Brad Boxberger is expected to begin a strength program in the coming weeks and begin a throwing schedule in mid-November. A right forearm strain limited him to just 22 games in 2023, where he posted a 4.95 ERA for the Cubs. He was expected to be a key piece to the Cubs’ reliever corps this season. Boxberger, 35, has a club option for 2024.

Madrigal (right hamstring strain), pitchers Nick Burdi (appendicitis, ulnar nerve irritation), Brandon Hughes (left knee inflammation) and Ethan Roberts (Tommy John) are expected to have normal offseason progressions heading into Spring Training.