Cartilage function

Cartilage does three things: it withstands forces that press down on it, it improves the resilience of bone, meaning its ability to take a blow without breaking, and it provides support exactly where the skeleton needs to bend instead of staying rigid.

It pulls this off with a different chemistry. Unlike bone, the cartilage matrix contains no calcium. What it has in abundance is chondroitin, a substance that gives it elasticity and flexibility, and that changes the kind of strength involved: instead of being hard, it gives and springs back. And one of its types, hyaline cartilage, contributes something very specific: a resilient surface with minimal friction. It is the difference between dragging a box across the floor and pushing it across an ice rink: the same load, far less drag.

One point tends to surprise people. Cartilage is aneural: it has no nerves. Damaged cartilage does not cause pain on its own. When someone with osteoarthritis, the wearing down of the cartilage in a joint, feels pain, that pain usually comes from neighboring structures that become irritated, especially from inflammation of the joint and the bone.