New England Patriots tight end Rob Gronkowski, who has been sidelined since Dec. 9, will have surgery on both his anterior cruciate and medial collateral knee ligaments on Thursday, multiple media outlets reported Tuesday.

Gronkowski suffered the season-ending injury in the Week 14 game against the Cleveland Browns when safety T.J. Ward went low to make an open-field tackle.

An arm injury prevented Gronkowski from starting the season on time. He returned in Week 7, and played in seven games.

According to the Boston Globe, Gronkowski will undergo surgery to repair the torn ligaments in his right knee.

Dr. James Andrew, who previously consulted with Gronkowski on a forearm injury, will perform the surgery. The procedure was delayed four weeks to allow the swelling in Gronkowki’s knee to subside.

The fourth-year tight end’s career has been marred by injuries. This will be his sixth surgery since November 2012. Gronkowski has missed 14 games the last two seasons.

Even with the setbacks, Gronkowski has also been an offensive force for the Patriots when healthy. In just seven games this season, he collected 39 passes for 592 receiving yards and four touchdowns.

In four seasons with the Patriots, Gronkowski has made two Pro Bowls, is a two-time All-Pro selection and has amassed 226 catches for 3,255 receiving yards and 52 touchdowns.

He signed a record six-year, $54 million contract in 2012, which was the largest contract ever given to a tight end.