Whenever the joint breaks down from overload, small pieces of the matrix the cartilage cells are in will degrade. These small nanomolecules collect in the joint fluid and irritate the inflammatory cells. They know something’s gone wrong, so a healing response is generated. When this healing response called inflammation goes on too long, usually more than two years, is when the brain decides the joint has wasted enough energy in the futile process and the joint is destroyed in favor of fusion rather than regeneration.
This is a critically important concept to grasp. Inflammation IS healing! That’s a key concept because without inflammation, there is no healing. So, the healing response IS the inflammatory response. We just have to control it.