Cartilage is a connective tissue which acts as a cushion between bones/ joints and gives shape and support to other parts of the body. It is elastic and compressible. It is composed of water, chondrocytes, collagen and proteoglycans. The structure of cartilage consists of proteoglycan monomers attached by a link protein to a molecular hyaluronic acid. This is all woven with collagen fibrils. Hyaline cartilage is an articular cartilage which provides a smooth gliding surface between joints. The structure of hyaline cartilage consists of four layers: a) superficial b) middle c) deep d) calcified.
Cartilage injuries are relatively common, the commonest being those of the knee joint. Knee cartilage may get injured as a result of trauma (as from sports injuries) or normal wear and tear (example-Arthritis). Wear and tear of the cartilage causes rubbing between the bones/ joints. This wear and tear can be a result of overuse of the cartilage, injury to the cartilage, excessive weight or improper alignment.
Knee joint: The knee joint is composed of the thigh bone (femur), the leg bone (tibia) and the knee cap (patella). There are two types of cartilages in the knee joint: a) the articular cartilage which covers the ends of the bones at the knee joint and the menisci which are shock absorbing. The knee joint also has two major ligaments which connect the femur to the tibia: a) anterior cruciate and b) posterior cruciate. They support the knee joint from the front and the back respectively.
Since articular knee cartilage cannot heal itself due to a lack of blood supply, external treatment options are used to repair the damaged cartilage. The aim of treatment is to reduce pain and improve function. Treatment options for cartilage injuries include: a) Anti inflammatory medication b) Injections c) Gene therapy d) Platelet rich plasma e) Growth factors f) Stem cells g) Drilling and debridement of cartilage.
Anti inflammatory medicines reduce inflammation in the joint but have side effects on the cardiovascular and gastrointestinal systems. Various types of injections may be given like steroid injections- cortisone- to reduce inflammation in osteoarthritis, hyaluronic acid (viscosupplementation), glucosamine etc. There is ongoing research on using stem cells (bone marrow or fat) to generate new cartilage. Stem cells from own body or from donor may be used. Growth factors inserted into scaffolds, stimulate the cartilage matrix to produce chondrocytes (cartilage cells). Platelet rich plasma (PRP) obtained from the person’s blood is injected into the person’s knee. Platelets are rich in growth factors and help to repair the cartilage. In gene therapy, therapeutic genes are delivered to the synovium (lining of the joint) or directly to the injury site. Drilling and debridement includes smoothing rough cartilage by drilling and removing injured cartilage or loose bodies.
In case of severe arthritis of knee joint where the knee cartilage is greatly damaged, total knee replacement has to be performed. There are three components in an artificial knee joint: a) the patellar component made of plastic, b) the tibial component made of plastic and metal, and c) the femoral component made of highly polished metal. But, complications may occur in a few cases of total knee replacement. These include: a) loosening of the artificial knee joint b) fractures c) infection of the wound d) persistence of pain e) blood clots (deep vein thrombosis) f) stiffness in the joint g) ligament, artery or nerve damage h) allergy to metal components.
The following video presents details on cartilage injury of the knee joint and its treatment. See the video below and get answers to all your related queries about Knee pain, arthritis and Injured knee Cartilage: