After missing the past 40 games, Minnesota Timberwolves forward Robert Covington underwent surgery on his right knee on Monday morning, the team announced.

Covington has played in just 22 games for the Timberwolves this season, where he was landed as part of the blockbuster trade that sent Jimmy Butler to the Philadelphia 76ers in November. Covington injured his right knee in their December 31 game against New Orleans, and hasn’t played since.

The injury was initially called a bone bruise but he started experiencing swelling in the knee joint, which prolonged his recovery. The “diagnostic arthroscopic procedure” he underwent on Monday included the debridement and removal of loose bodies in his knee. The team did not offer a timetable for his recovery, though he had already been ruled out for the remainder of the season before the surgery.

Covington averaged 14.5 points and 5.7 rebounds in his 22 games with Minnesota this year. He put up 12.6 points and 5.4 rebounds last year with the 76ers, his last full season.

The Timberwolves currently sit with a 34-42 record with just six games left, and are set to miss the postseason. Minnesota has been hit with multiple key injuries late this season. Guard Derrick Rose underwent season-ending elbow surgery last month after an MRI revealed he had a chip fracture and loose body in his right elbow. Jeff Teague re-aggravated a left foot injury that sidelined him earlier in the year late last month, too, landing the guard in a walking boot.

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