Articular cartilage, especially that found in weightbearing joints, is uniquely structured to withstand tremendous abuse. It can resist crushing by static loads considerably greater than those required to break a bone. No painful sensations are elicited in traumatized cartilage because it lacks nerves. The chondrocytes in weight-bearing joints are genetically programmed to tolerate crushing forces without overreacting, such as by inducing their surrounding matrix to undergo extensive dissolution or by laying down excessive amounts of matrix. Such responses would markedly alter the surface contour of the cartilage in a manner that would interfere with the normal joint motion.

As soon as the joint cavity appears during development, it contains watery fluid. The joint capsule develops an outer fibrous portion that is lined with an inner, more highly vascularized synovial membrane. Although this membrane lines the fibrous capsule as well as any bony surfaces, ligaments, and tendons within the joint, it does not line the surfaces of the joint discs, menisci, or articular cartilage.

The synovial membrane is the site of formation of the synovial fluid that fills the joint cavity. This fluid is similar to that found in bursae and tendon sheaths. Before birth, it is sticky, viscous, and much like egg white in consistency. Only a small amount of the fluid is normally present in a joint cavity, where it forms a sticky film that lines all the surfaces of the joint cavity (for example, the adult knee joint contains only a little more than 1 mL of synovial fluid). Even so, before birth and thereafter, the fluid is the chief source of nourishment of the chondrocytes of the articular cartilage, which lacks blood and lymphatic vessels.

The articular cartilage is never very thick, averaging 1 to 2 mm in thickness in the adult and reaching a maximum of 5 to 7 mm in the larger joints of young individuals. However, compared with cells in the vascularized tissue of the body, which are not more than 25 to 50 µm from a capillary, the chondrocytes are at an enormous distance from their source of nourishment. Joint activity enhances both the diffusion of nutrients through the cartilage matrix to the chondrocytes and the diffusion of metabolic waste products away from them. The alternating compression and decompression of the cartilage during joint activity produce a pumping action that enhances the exchange of nutrients and waste products between the cartilage matrix and the synovial fluid.

In some developing joints, the mesenchymal tissue between the cartilage rudiments, instead of disappearing, gives rise to a fibrous sheet that completely divides the joint into two separate compartments. The sheet develops into an intra-articular disc, which is made up of fibrous connective tissue and, possibly, a small amount of fibrocartilage. A separate synovial cavity develops on each side of the disc, as found in the temporomandibular joint.

In other developing joints, the mesenchymal tissue between the cartilage rudiments gives rise to a fibrous sheet that is incomplete centrally. This fibrous sheet projects from the joint capsule into a single joint cavity and gives rise to articular menisci consisting of fibrous tissue and possibly a small amount of fibrocartilage, such as found in the knee joint.