Synovial fluid is a viscous liquid that lubricates the cartilage and joint surface in order to reduce friction and wear. It also helps to cushion the joint and absorb shock by providing a cushion of fluid between the joint surfaces. It also helps distribute nutrients to the joint and cartilage, and helps remove metabolic waste products.
Cartilage is a smooth, flexible connective tissue which covers the ends of bones within a joint. It provides a protective cushion between the bones, helping to reduce friction and wear and enabling smooth, pain-free movement of the joint. It also helps to distribute forces evenly across the joint, and helps to absorb shock.