What does osteochondritis dissecans mean in the knee? what does hypointense mean on an mri scan of the knee? can you tibia slip out of place?

Bone/cartilage shift: Osteochondritis dessicans refers to a condition in which a piece of cartilage and a small piece of bone have come detached. It is common in the knee. If the piece does not move much it may not hurt. However, it is common for it to get "stick" in the knee joint and may need surgery. Hypointense means loss of bone density which is not normal. The tibia can slip out of place somewhat.

See answer below: Osteochondritis dissecans usually occurs in the knee, but may in the elbow. A piece of cartilage along with a thin layer of bone becomes loose, caused by reduced blood flow to the bone. May result from an injury, but may also occur without event. Hypointense describes the "coloring" of the fragment on the mr image. Tibia cannot "slip out" without traumatic event.