OCD stands for osteochondritis dissecans. OCD refers to a problem in the knee where the layer of bone underneath the cartilage separates from the bone. The piece of bone and cartilage separate most often at the end of the femur (thigh bone).
If the fragment detaches even partially, surgery is needed to put it back in place. If the problem is bad enough, the fragment may have to be removed.
If the loose bone fragment is in a weight-bearing area of your bone, the surgeon tries to reattach it if at all possible. Tiny metal pins or screws are used to hold the fragment in place. If for any reason the bone has to be removed, donor bone from a bone and tissue bank may be used to fill in the defect.
Another way to repair this problem is called an autograft. Tissue taken from the patient's own knee is used. In this case, surgeons graft a small amount of bone (osteo) and cartilage (chondral) from the donor site to put into the hole left by OCD.
With any of these methods problems can develop. For example, infection around the donor or graft site can occur. Shaping the graft to fit the same shape as the defect isn't always possible.
New methods for dealing with this problem are under investigation. For example, a new technology called autologous chondrocyte implantation (ACI) is currently being developed. It involves using cartilage cells (chondrocytes) to help regenerate articular cartilage.
And a new repair technique has shown good results in as little time as three months. Plugs of bone are taken from inside the patient's own knee. The plugs are used like pegs or pins to hold the torn fragment in place. The bone cells help stimulate the formation of new bone cells. Healing time is cut in half compared to using pins or screws.
To know what goes on exactly, you'll have to ask your surgeon which repair technique he or she is planning to use.