I have articular cartilage damage in both knees. could this be caused by inflammatory arthritis? or is it always wear and tear?

Can be inflammatory: Articular cartilage, which is the coating on the ends of our bones, can sustain damage from many sources causing it to erode away at different rates. Think of your teflon coated pans at home. The teflon can get scratched or peel, or rub away with abrasives over time. Your cartilage can scratch, split, detach from the bone surface, blister, have immune system or gout attacks, or get infected.

See below: If only your knees are bothering you and donot have any other symptoms in your hands or feet and other joints most likely you have osteoarthritis from "wear and tear" see enclose recommendations for conservative treatment in an arthritic knee . Ask your orthopaedic surgeon for guidance