Articular or hyaline cartilage is the tissue lining the surface of the two bones in the knee joint. Cartilage helps the bones move smoothly against each other and can withstand the weight of the body during activities such as running and jumping. Articular cartilage does not have a direct blood supply to it so has little capacity to repair itself. Once the cartilage is torn it will not heal easily and can lead to degeneration of the articular surface, leading to development of osteoarthritis.
The damage in articular cartilage can affect people of all ages. It can be damaged by trauma such as accidents, mechanical injury such as a fall, or from degenerative joint disease (osteoarthritis) occurring in older people.
Patients with articular cartilage damage experience symptoms such as joint pain, swelling, stiffness, and a decrease in range of motion of the knee. Damaged cartilage needs to be replaced with healthy cartilage and the procedure is known as cartilage replacement. It is a surgical procedure performed to replace the worn-out cartilage and is usually performed to treat patients with small areas of cartilage damage usually caused by sports or traumatic injuries. It is not indicated for those patients who have advanced arthritis of the knee.
Cartilage replacement helps relieve pain, restore normal function, and can delay or prevent the onset of arthritis. The goal of cartilage replacement procedures is to stimulate growth of new hyaline cartilage. Various arthroscopic procedures involved in cartilage replacement include:
Microfracture : In this method, numerous holes are created in the injured joint surface using a sharp tool. This procedure stimulates healing response by creating new blood supply. Blood supply results in growth of new cartilage.
Drilling : In this method, a drilling instrument is used to create holes in the injured joint surface. Drilling holes creates blood supply and stimulate growth of new cartilage. Although the method is similar to microfracture, it is less precise and the heat produced during drilling may damage other tissues.
Abrasion Arthroplasty : High speed metal-like object is used to remove the damaged cartilage. This procedure is performed using an arthroscope.
Osteochondral Autograft Transplantation : Healthy cartilage tissue (graft) is taken from the bone that bears less weight and is transferred to the place of the injured joint. This method is used for smaller cartilage defects.
Osteochondral Allograft Transplantation : A cartilage tissue (graft) is taken from a donor and transplanted to the site of the injury. Allograft technique is recommended if larger part of cartilage is damaged.
Autologous Chondrocyte implantation : In this method, a piece of healthy cartilage from another site is removed using arthroscopic technique and is cultured in a laboratory. Cultured cells form a larger patch which is then implanted in the damaged part by open surgery.
Following the surgery, rehabilitation procedures are advised to necessitate healing and to restore normal functioning of the joint.
Femoral condyle (above) with large, broad area of exetnsive cartilage injury and loss (should appear like the surface of a cue ball). Fraying of the cartilage noted on the tibial plateau as well (below).