<prompt> Answer this question truthfullyWhat is osteoarthritis, and what is a characteristic feature of the subchondral bone associated with it?  <response>: <reason> Osteoarthritis is a degenerative joint disease that affects the cartilage and underlying bone of joints. A characteristic feature of the subchondral bone associated with osteoarthritis is eburnation polishing, which occurs due to friction from the opposing bone surface. 