Unlike many other tissues, immature articular cartilage differs considerably from adult articular cartilage.
On gross inspection, the cartilage from skeletally immature individuals appears blue-white, presumably because of the presence of vascular structures in the underlying immature bone, and is relatively thick. The thickness reflects the two tasks of the cartilage mass: to serve as a cartilaginous articular surface for the joint and to be a source of endochondral ossification of the underlying bone. Immature articular cartilage is also considerably more cellular than the adult tissue. With increasing age, the cartilage undergoes changes in matrix organization, mechanical properties, and cell function. All of these changes increase the risk of tissue degeneration. 15,16 The tensile strength of the superficial cartilage layer decreases and perhaps most important, the ability of the chondrocytes to maintain and restore the tissue diminishes.17,18