Articular cartilage is the lining cartilage at the end of bones of all synovial or bag like joints. It has the properties of stress dissipation and lowering the friction within joints. It is responsible for preserving the effortless mobility of all joints. Complete loss of articular cartilage results in osteoarthritis, which is a chronic debilitating disease in which movement becomes painful along with joint stiffness. This osteoarthritis is a form of joint failure like heart failure or kidney failure. In the less severe forms, the loss may be localised. It is seen in the following conditions.
Chondral fracture-this means a fracture of the cartilage. It results when the cartilaginous surfaces at the ends of the femur, patella and the tibia grate against each other in a single twisting injury. It can be associated with a ligamentous injury like an anterior cruciate injury. If seen within two weeks it may be possible to re attach the piece to its bed but later when healing has taken place, this may not be possible. Chondromalcia- This was the earlier term used for all knee pain. Here the cartilage softens and later gets eroded to the underlying bone. This usually affects the under surface of the knee- cap. Similarly, the femoral cartilage may be involved. The causes may be chemical, mechanical or unknown. There are four grades of severity. Chondromalacia becomes osteoarthritis when there are kissing lesions affecting both contacting bones. Osteochondritis Dissecans- This is a chronic condition affecting young children in the age group 10-13 years. It results in the flaking off a small area of the weight-bearing surface of the femur. Here the cartilage with underlying bone chips off. The fragment, which is identified at first by swelling, separates from its bed later and may become a loose body. The bed heals over. Osteoarthritis- In this disease there is complete erosion of the cartilage to the underlying bone involving both the contacting surfaces. It was thought earlier that osteoarthritis is a degenerative disease affecting elderly people. However it is now clear that the articular cartilage damage is multifactorial resulting from genetic causes, repeated micro trauma in obese people, knee mal alignment as in bowlegged and knock-kneed individuals and secondarily from a long list of causes which includes instability, meniscal tears, infection etc.
Articular cartilage by itself has no pain fibres. Therefore, there may be no pain at all in early stages of cartilage damage. Pain signals emanate from other tissues surrounding the joint like the capsule, irritated by the products of cartilage damage. There may be a crunching or grating sensation within the joint. There may be minor aches and pains and some swelling. Sometimes if there is a loose body then the patient may fall unexpectedly. There may be a locking feeling due to pain or a loose body. Swelling.
Obesity due to overloading of the cartilage. This is like driving an over-laden truck or car leading to tyre wear out. Severe bow- legs and Knock- knees leading to non-uniform over-loading of one half of the knee like a tyre mal-alignment in your car. Participation in certain sports like football, hockey, basketball, athletics and cricket. When there is a tear of the Menisci, resulting in loss of weight dissipation.
R.I.C.E (Rest, Ice, Compression, Elevation) in the initial stages Physiotherapy- to improve the strength of the thigh muscles may be useful for chondromalacia patella or osteoarthritis.
Arthroscopy- an Arthroscopic evaluation is the most reliable way to identify early chondral separations, osteochondritis- dissecans. It may be possible to get a separating fragment to reattach by drilling through it into the bone. If the separation is full and recent, then it may be possible to reattach it by pins or screws. Loose fragments, in which the bed and the fragment have healed and it is impossible to restore the normal anatomy, can be excised. The latest techniques of cartilage surgery are available in India today. These are microfracture, mosaicplasty and autologous cartilage cell implant. Mosaicplasty- In this procedure islands of cartilage and underlying bone are cored out from an unimportant non-weight bearing portion of the joint and are reimplanted into the weight-bearing portion of the joint. Autologous cartilage cell transplant-In this procedure cartilage cells are harvested from the patient’s knee, cultured in a medium and re-implanted into the defect. This procedure is very useful for young patients with localised articular cartilage defects. These defects do not have the potential to heal and if left untreated progress to osteoarthritis. Ligament reconstruction may have to precede this procedure.