Articular cartilage is the hard, slippery ‘gristle’ that covers the ends of the thighbone, shinbone and the back of the kneecap. It can be torn by a bad fall, slow damage after a knee injury, general wear and tear or poor blood supply to the joint. Cartilage does not naturally repair itself, and once torn or damaged, fragments of the cartilage may break off, or the damaged surface may cause catching and locking.

Meniscus cartilage is the rubbery shock absorber that is attached to the ligaments in the knee. Meniscal tears can be caused by twisting, pivoting or through direct contact. If a piece of meniscus tissue is torn, it can move around in the knee, getting trapped between the bones of the joint.

The lining of the knee joint is called the synovium. It becomes inflamed as a response to injury or damage, and the knee can be very swollen, warm and tender. Chronic inflammation leads to thickening of the synovium, which means that it can get trapped between the joint surfaces. If this continues untreated, it eventually causes softening of the articular cartilage (see above) and progressive arthritic changes.

These cartilage-related problems can be treated with debridement (see below). Other cartilage surgical procedures include microfracture and chondroplasty.

The inflammation as a result of torn or damaged cartilage can be painful and the sensation of catching and locking can make activities difficult.

The history and physical exam are usually enough to make a diagnosis. X-rays are taken to rule out fractures and an MRI scan may be used to confirm the tear.

Arthroscopic debridement is carried out on more minor damaged areas and is aimed at removing debris and smoothing surfaces to prevent or delay further progression of the problem. Debridement might involve one or more of the following surgical procedures:
Trimming or removing thickened synovium (see above)
Removing loose debris within the joint using a tiny vacuum suction device
Shaving the surface of the articular cartilage to smooth it out
Trimming or removing meniscus cartilage

After debridement, return to normal activity will be governed by how much discomfort and swelling you experience. These are not usually severe and, if you were quite fit before surgery, you could be back to normal in a few weeks.