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Knee Joint Surface damage (Chondral)
Normal articular cartilage is tough and hard wearing. In many people it will not wear out and lasts a lifetime of coping with a million steps per year. Two normal cartilage surfaces lubricated with normal knee synovial fluid rubbing on each other have a coefficient of friction that is very slippery; more slippery than two ice cubes rubbing together.
Chondral damage means that there is an area of damage in the rubbery cartilage that covers the ends of the bones inside the knee joint. This cartilage acts as a shock absorber, and allows the bones to move smoothly over one another.
What causes Knee Joint Surface damage?
Chondral damage can be caused by an injury such as a twist, fall or direct blow to the knee, or the cartilage can wear away with time (known as osteoarthritis). Chondral damage caused by an injury often accompanies injury to a ligament, for example an anterior cruciate ligament injury.
In teenagers, sometimes a piece of the cartilage breaks away with a piece of bone, causing a type of damage known as osteochondritis dissecans.
There are no nerves in the cartilage so there are sometimes no symptoms at first. However, damage can disrupt the normal function of the joint and cause on-going pain and inflammation, as well as limiting mobility.
A diagnosis made during a medical examination can be backed up with an MRI scan to show the extent of the damage. You may also be offered an arthroscopy which allows the knee specialist to examine the joint and, in some cases, treat it at the same time.
How is it treated?
Cartilage does not have the ability to repair itself, so you may need knee arthroscopy to treat the condition.
An injury to the knee joint surface may occur with any trauma to the knee. When a fragment of cartilage breaks free this causes severe pain, swelling and catching in the knee. It is occasionally possible to re-attach these loose fragments and reconstruct the joint surface.
The most common situation is that the fragments need to be removed with keyhole (arthroscopic) surgery. The damaged area may simply require tidying up or chondroplasty to remove any loose edges. If the joint surface damage is more significant, surgery can then be carried out to try and encourage new cartilage to form, in the form of a Microfracture Procedure.
Articular cartilage has very low potential for self-repair. Once damaged, it does not tend to heal. Several procedures are available to regenerate joint surface cartilage in the form of Microfracture, OATS, and Cartilage Transplantation (MACI) though restoration to complete normality is usually not possible.