ESPNChicago’s Nick Friedell is reporting that Chicago Bulls star Joakim Noah will undergo surgery Thursday to repair a torn ulnar collateral ligament. Noah reportedly injured the ligament in a game against the Sacramento Kings in late November. He has been trying to play with his thumb taped, but the Bulls announced that Noah has had “ongoing discomfort and slight functional impairment.”

The ulnar collateral ligament is the ligament at the base of the thumb that keeps the thumb from being pulled away from the other four fingers. It is often sprained and not torn completely. If so, the injury can be treated nonoperatively with taping or a cast. If the joint at the base of the thumb is unstable due to the injury, surgery is often required to reattach the ligament.

Noah will likely be in a cast for several weeks after surgery to protect the ligament while it heals. The Bulls are reportedly saying their center will likely miss 8-10 weeks.

Read more about an ulnar collateral ligament injury of the thumb and its surgery.