"I have like soft cartilage on the inner side of my knee that's causing [the pain]," Spencer said. "It's not stopping the banging of the bone. It's going to take a little bit more time to heal, and we really don't have time right now." When you hear about banging of bones in the knee, it raises questions about the long-term health of a player and whether the cartilage is gone. Microfracture surgery is a procedure that creates fractures in the bone to develop new cartilage.