Smooth, rubbery tissue that lets bones glide. It has no blood supply, so it's nourished by joint fluid moved by motion.
Movement feeds it
Loading and unloading during movement pumps nutrients into cartilage.
Supplements
Large trials of glucosamine and chondroitin show little or no benefit for knee osteoarthritis pain overall.
Evidence & sources
Large studies have found glucosamine and chondroitin generally don't relieve osteoarthritis pain better than placebo. Evidence: moderate. Known: Including the NIH-funded GAIT trial. Unknown: Some subgroups are debated. Source: NIH NCCIH, Glucosamine and Chondroitin for Osteoarthritis (Current revision).