WHAT IS OSTEOCHONDRAL AUTO-GRAFTING?
Osteochondral auto-grafting is useful to repair cartilage defects that are relatively small, < 1.5 cm squared or the size of a dime. An osteochondral graft is a cartilage and bone plug that is taken from a minor load bearing area within the same knee (auto graft). Specially devised instrumentation is used to harvest exactly matched cylinders of cartilage and bone to fill in the areas of damage. The technical systems are known as: OATS™, COR™, SDS™ and Mosaicplasty™. All these systems essentially do the same procedure but have subtle differences between them, and some require an open technique versus an arthroscopic performed technique.
WHAT IS OSTEOCHONDRAL ALLO-GRAFTING?
Large cartilage injuries are best treated by osteochondral allo-grafting so as to not create a donor site problem. The procurement of a cadaveric allograft requires the use of a radiographic marker x-ray of your knee to match the appropriate size. The x-ray is then sent to a commercial procurement company which will find a suitable match, and after screening the tissue for absence of disease, the fresh tissue will be available for transplantation. Fresh tissue is preferable as cartilage viability is associated with a better long-term result. When the tissue becomes available you will be contacted, and you will need to come in within one week of the tissue being available. It may take as quick as two weeks or as long as three to six months before the appropriate match is available. Tissue typing is not required as in other organ transplantation with a blood supply such as kidney heart or lung. Rejection of bone and cartilage is very rare and usually manifests as persistent swelling and a nonunion of the bone to bone junction.
WHAT WILL HAPPEN DURING MY SURGERY?
Arthroscopic osteochondral grafting is performed for small chondral defects on a day surgery basis or overnight admission. Typically an OATS™ system is used for this purpose. The procedure takes approximately 60 minutes to perform. A drain isleft inside the joint overnight to remove any postoperative bleeding from the donor site. The drain is either taken out in the hospital the following morning or the office. The technique involves harvesting and osteochondral plug from a minor loadbearing area within the knee joint and transferring it to a recipient donor site were the cartilage defect exists. In this way bone-to-bone healing occurs within six weeks after surgery with mature cartilage on the surface.
Large defects may be treated by multiple small osteochondrals graft through an open procedure requiring two to three days in the hospital postoperatively. Alternatively, a single large osteochondral allograft may be utilized. The choice is dependent on the defect size and whether it is well contained or there is bony insufficiency present. This would be discussed in the office setting.