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ARTICULAR CARTILAGE (CHONDRAL) DAMAGE AND REPAIR

All the bony surfaces within the joint of the knee are lined by hard smooth articular cartilage. This cartilage is almost marble hard and smooth to allow friction-free motion of the knee.

When this cartilage sustains an acute injury which involves a full thickness loss of articular cartilage with exposed bone, it results in pain and accelerated knee wear.

It is very important to note when this is diagnosed that if the injury is still fresh the articular cartilage does have the capability to heal spontaneously without surgical intervention. This does however involve a minimum of four months cessation of all impact sports and protection of the knee. Often a hinged knee brace with controlled in range of motion is needed.

When the articular cartilage fails to heal, various options are available.

The most widely used and one of the most successful options is a Steadman Microfracture Chondroplasty. This involves arthroscopically cleaning up the lesion to make sure the exposed bone is fresh without the lining of scar tissue that normally covers it. Multiple small holes are then made into the bone which allows bone marrow and blood to leave the bone and enter the knee.

The bleeding in the lesion creates what is known as the “super clot” in the defect or lesion. This “super clot” traps bone marrow cells leaking out of the bone marrow. These bone marrow cells are the patient’s own “stem cells”. With sufficient stimulation in the form of movement without load the stem cells are stimulated to form cartilage. The cartilage filling the defect is fibro or scar cartilage, not elastic cartilage with which we are born. This however creates a smooth, hard plug to fill the defect.

Further options for filling this defect involve the harvesting of articular cartilage cells which are then sent away to a lab to grow a cartilage sheet which can be re-inserted into the knee six weeks later.
Another option now available is the insertion of an ‘off-the-shelf’ scaffold into the chondral defect into which the body lays down chondrocyte cells forming an articular cartilage plug.

Should the various biological options fail there are further non-biological options involving a metal cap (Hemicap by Arthrosurface).

Full Thickness articular cartilage damage

Full Thickness articular cartilage damage

Microfracture pick used to release bone marrow stem cells

Microfracture pick used to release bone marrow stem cells

After micro fracture of damaged area

After micro fracture of damaged area

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