i'm about 4 1/2 months post-op, i had arthroscopic surgery with microfracture to repair torn cartilage on my medial femoral condyle. A few weeks ago i jumped knees first onto a sled and have been having problems since. i am experiencing alot of stiffness and a little swelling, there is also something the feels like it is moving when i extend my knee. should i be worried about another injury?