Knee Articular Cartilage DamageSummary & Treatment
Knee Articular Cartilage is the tough but flexible tissue that covers the ends of bones at the knee joint. Healthy knee articular cartilage helps movement by allowing the bones to glide over each other. It also protects the bones by preventing them from rubbing against each other.
Injured, inflamed, or damaged knee articular cartilage can cause symptoms such as knee pain and limited movement. It can also lead to knee joint damage and deformity.
Minor knee cartilage injuries may get better on their own within a few weeks, but more severe cartilage damage may eventually require surgery.
Causes of knee articular cartilage problems include:
- Tears and injuries, such as sports injuries
- Damaged Menisci
- Genetic factors
- Gradual wear and tear
- Other disorders, such as some types of arthritis
Osteoarthritis results from breakdown of cartilage.
Signs & Symptoms
Symptoms of knee articular cartilage damage include:
- Knee pain – this may continue even when resting and worsen when weight is put on the knee
- Swelling – this may not develop for a few hours or days
- Clicking or grinding sensation
- Joint locking, catching or giving way
It can sometimes be difficult to tell a cartilage injury apart from other common knee injuries, such as sprains, as the symptoms are similar.
Sprains and minor knee articular cartilage damage may get better on their own within a few days or weeks. However more severe cartilage damage most likely won’t improve on its own and if left untreated, can eventually wear down the knee joint.
Serious knee articular cartilage damage is probable when:
- The knee joint can’t move properly
- The knee pain can’t be controlled with ordinary painkillers
- No weight can be put on the knee or it gives way when used
- The knee looks crooked or has unusual lumps or bumps (other than swelling)
- Numbness, discolouration or coldness in any part of the knee
- Symptoms doesn’t start to improve within a few days of self-treatment
Tests such as an X-ray, magnetic resonance imaging (MRI) scan or arthroscopy (a type of keyhole surgery used to look inside joints) may be needed to find out if the cartilage is damaged.
Self-care measures are usually recommended as the first treatment for minor joint injuries. For the first few days:
- Protect the knee from further injury by using a support, such as a knee brace
- Rest the knee
- Elevate the knee and apply an ice pack regularly
- Take ordinary painkillers, such as paracetamol or non-steroidal anti-inflammatory drugs (NSAIDs)
- Get medical advice if symptoms are severe or don’t improve after a few days. Professional treatment such as physiotherapy, or possibly surgery may be needed.
Severe knee articular cartilage damage doesn’t tend to heal very well on its own, so surgery is often necessary in these cases.
Surgery is usually performed using arthroscopy – a type of “keyhole” surgery where special instruments are inserted into the joint through small cuts (incisions) – although sometimes larger incisions need to be made.
It’s normally carried out under general anaesthesia.
Some of the main procedures are:
- Lavage and debridement – the knee joint is cleaned out to remove any loose tissue and the edges of the damaged area are trimmed to make them smooth. It may sometimes be possible to repair the damage at the same time.
- Marrow stimulation (Microfracture) – tiny holes are made in the bone beneath the damaged cartilage. These holes become a channel through the surface layer of bone, called the subchondral bone, which is hard and lacks good blood supply. By penetrating this hard subchondral bone layer, a microfracture channel allows the deeper, more vascular bone to access the surface layer hence forming a super clot. This deeper bone has more blood supply, and the cells can then get to the surface layer and stimulate cartilage growth. The new tissue is a “hybrid” of articular-like cartilage and fibrocartilage.
- Mosaicplasty – small plugs of healthy cartilage from non-weightbearing areas of a joint, such as the side of the knee, are removed and used to replace small areas of damaged knee articular cartilage.
- Osteotomy – the alignment of the leg is altered slightly to reduce pressure on the damaged area and improve pain. This usually involves adding or removing a wedge of bone from the shin or thigh bone. The bone is fixed with a plate until it heals.
- Knee replacement – replacing the whole knee joint with an artificial one, is occasionally necessary if the damage is particularly severe.
There are also a number of alternative surgical techniques that are sometimes used to treat cartilage damage, including:
- Allograft osteochondral transplantation (AOT) – similar to mosaicplasty, but the replacement cartilage is obtained from a recently deceased donor and is used to repair larger damaged areas.
- Autologous chondrocyte implantation (ACI) – the surgeon first takes a small sample of cartilage cells from the joint. These are then used to grow more cells in a laboratory and the new cells are used to replace the damaged cartilage.
- Artificial scaffolds – a special patch or gel is used to repair the damaged cartilage. It may be used in combination with marrow stimulation or on its own.