Minnesota Timberwolves All-Star forward Jimmy Butler left the game against the Rockets on Friday with a right knee injury. He fell to the ground in pain after grabbing a loose ball. He needed help from trainers to get up and get off the court. An MRI later revealed a partial tear of his medial meniscus.

The meniscus is a cushion and shock absorber between the thighbone and shinbone. Changes in the meniscus are part of the normal aging process in the knee. Trauma can injure the meniscus during quick changes in direction, jumping and cutting. The meniscus is often injured when the anterior cruciate ligament (ACL) is torn.

Many meniscal problems feel better over time. Some large traumatic tears near the attachment to the knee capsule can be repaired, but require a prolonged recovery time — the better part of a year. Large detachments near the center of the joint are just removed, like a haircut.

Butler had surgery on Sunday and is out indefinitely. According to ESPN, Butler has shared to those close with him that he hopes to return by the time the playoffs start, suggesting that the meniscus was partially resected.

This article was made by Lainie Mabe and David Ring