There are three different types of cartilage found in the body: articular (or hyaline) is a thin layer of tough, elastic cartilage that covers the end of the tibia and fibia bones in the leg.
Articular cartilage is a smooth tissue that provides an almost frictionless surface or cushion that allows the bones to move without causing discomfort. In a healthy knee joint this cartilage is protected by menisci which are like shock absorbers that also help to lubricate the joint and keep the knee stable. These menisci can be torn as a result of an injury, causing knee pain.
Injury to the articular cartilage, also known as chrondial injury, happens when the knee joint loses the full protection of the menisci which causes movement of the joint to become painful (see symptoms). Because there is no blood supply to the cartilage, any damage takes longer to repair and, over time, this can lead to osteoarthritis.
The usual symptoms of articular cartilage injury include swelling in the joint that lasts for more than a day, severe pain and stiffness/loss of movement at the knee.
Your doctor will examine your knee and may refer you for an MRI scan to reveal the extent of any injury. A more invasive arthroscopy may also be recommended, where a tiny camera is inserted into the knee under a general anaesthetic. An x-ray image may also be taken to see if there is any fracture accompanying damage to the cartilage.
Younger people (under the age of 35) often risk injury particularly if they play sports, when cartilage can be damaged by tearing a ligament, a fall or a bone dislocation.
Damage to the articulate cartilage can also happen as a result of infection, joint inflammation (eg, gout or rheumatoid arthritis) or bone misalignment. Sometimes it is caused by ‘wear and tear’, particularly among older and obese people, or among those who are inactive or less mobile and find it hard to take regular exercise.
If you play sports there is always some risk of injury. However, these risks can be reduced by adopting better techniques that make full use of your strongest muscles and place less strain on your joints.
It’s also a good idea to keep your weight/BMI under control through a combination of healthy diet and regular exercise.
There are also a number of other positive steps you can take to slow the development of osteoarthritis. These include:
Articular cartilage does not repair itself, so left untreated it can result in osteoarthritis. It is therefore a good idea to see a doctor as soon as possible after injuring your knee so you can get a fast diagnosis and start treatment.
If damage to the cartilage is not too severe, you may be offered steroid injections, anti-inflammatory drugs and/or physiotherapy. However, for more serious injuries joint replacement surgery is likely to be the best option. You will be able to discuss these options with your doctor.
The London Knee Unit offers advice and treatment for conditions that affect all parts of the knee. If you would like to find out more about the treatments we provide for orthopaedic conditions please visit our other musculoskeletal sites:
Musculoskeletal Foot and Ankle injuries Nerve injuries Shoulder injuries