For cartilage damage of up to two centimeters in size, cartilage-regenerating procedures can be helpful. These promote the later growth of cartilage tissue. Special instruments are used to make fine holes in the cartilage defect, thus forming a connection with the underlying bone. Stem cells can migrate through these from the bone marrow into the defect, so that replacement tissue of fibro-cartilage forms within the cartilage defect.

If the holes are made with a special chisel tool, this procedure is called microfracture; if, on the other hand, a drill or a fine Kirchner wire is used for this technique, it is known as the Pridie technique.

Note: As the heat of the drilling can damage cartilage tissue, in many centers the Pridie technique has given way to microfracture in recent years. If there is also bone disease, K-wire drilling is done instead, in order to reach the more deep-seated focus.

New techniques with encouraging results

Another development in this field is autologous matrix-induced chondrogenesis (AMIC). Here, in addition to the microfracture and previous removal of cartilage, a fine collagen membrane is used, and is stretched over the defect to protect it. Cartilage defects of over two centimeters in diameter can also be treated in this way, without fear of prematurely washing away the stem cells which have migrated in. The first results are encouraging, although the long-term outcomes cannot yet be predicted with certainty.

Abrasion arthroplasty is used only in exceptional cases today

In exceptional cases, abrasion arthroplasty is also used for cartilage regeneration. Here, the uppermost layer of the exposed bone in a cartilage defect is removed, creating a connection with the bone marrow. Stem cells can then migrate into the defect, thus creating fibro-cartilage (replacement cartilage).

However, the results of abrasion arthroplasty are often unsatisfactory. Up to 99% of those concerned are still restricted in the activities of daily living after the procedure, and only one out of eight is symptom-free after five years.