How It Works 1. How cartilage works in a healthy knee Cartilage is a form of extracellular matrix secreted by specialized cells called chondrocytes. Articular cartilage covers the end of the femur, the top of the tibia, and the back of the patella. It serves as a shock absorber and is essentially frictionless, providing a smooth surface for the contact and movement of the bones of the knee joint.
Meniscal cartilage is on the tibia and serves mostly as a shock absorber.
Autologous Chondrocyte Implantation is used to repair defects to the articular cartilage. Chondrocytes are one of the few cell types that can survive without being close to a blood supply. However, when the cartilage is damaged, the chondrocytes' distance from a blood supply means that they lack the ability to regenerate themselves, a process that requires an increased amount of nutrients and access through the blood stream to other cells and proteins that stimulate the regeneration. There are certain procedures that can be done through arthroscopic surgery to relieve the patient's symptoms. The damaged area is usually debrided, cleared of debris and dead cells, and the surface is smoothed.