Osteochondral Allograft Transplantation
The Osteochondral Allograft Transplantion Surgery, commonly known as OATS, replaces damaged cartilage in the knee with healthy cartilage from a donor, relieving pain and restoring movement and function to the joint. A mosaicplasty is the name for a general procedure that treats severe cartilage damage, and the OATS procedure is a type of mosaicplasty.
Cartilage, or chondral, damage is known as a lesion and can range from a soft spot on the cartilage (Grade I lesion) or a small tear in the top layer to an extensive tear that extends all the way to the bone (Grade IV or “full-thickness” lesion). Sometimes a piece of cartilage breaks off and causes more damage to the cartilage and bone as it is ground in the joint.
Chondral lesions may be degenerative (a “wear and tear” problem) or traumatic (caused by an injury such as falling on the knee, jumping down or rapidly changing direction while playing a sport). They do not always produce symptoms at first because there are no nerves in the cartilage. Over time, however, lesions can disrupt normal joint function and lead to pain, inflammation and limited mobility. The lesion may gradually worsen or cause other problems in the joint.
The OATS Procedure
The OATS procedure is a treatment option focusing on biologic joint preservation. It involves the repair of damage to a specific joint for patients who do not yet need or wish to delay joint replacement surgery. Joint preservation procedures are most often performed on patients with arthritis, chronic injuries and other joint-related conditions.
While cartilage is essential for ensuring smooth, painless movement of the joints, some areas have a more critical need for the support and cushioning provided by the cartilage. During the OATS procedure, small plugs of healthy cartilage are taken from a donor and transferred to the area of damaged cartilage. In other forms of the procedure, cartilage may be removed from the patient’s own joints. However, allograft means that the cartilage comes from a donor individual instead.
The OATS procedure is ideal for patients with small areas of cartilage damage that can be easily repaired with a graft. Widespread cartilage damage cannot usually be treated with this procedure, since the small plugs of healthy cartilage may not provide enough material to completely rebuild the cartilage of the joint.
General anesthesia is required for this type of surgery. During the procedure, your surgeon will make a very small incision over the affected joint and insert an arthroscope, a tiny instrument with a light and camera that provides a view of the area. Another very small incision is made in which other tiny instruments are placed to introduce the plugs of donor cartilage into the joint. The surgeon uses these tools to create openings in the damaged areas of cartilage to exactly fit these plugs, then grafts them into place. After they have been transplanted, the incisions are sutured closed.
Possible Complications of the OATS Procedure
There are a few difficulties that are associated with the OATS procedure. Donor grafts are not always readily available and occasionally some donors experience problems in a joint after the removal of the cartilage. Another potential complication, though uncommon, is a failure of the donor cartilage to integrate completely with the patient’s existing cartilage.
Although the OATS procedure is considered a safe form of surgery in which complications are rare, there are risks associated with any surgical procedure. Some of the risks in this case include infection, bleeding, deep vein thrombosis, numbness at the site, joint stiffness and damage to the surrounding tissue.
Recovery After the Surgery
After the OATS procedure, the joint that was operated on will be bandaged. Swelling will likely take place, for which regular applications of ice are recommended. Pain medication will be prescribed as necessary. Most patients will be on crutches for six to 12 weeks after surgery before they can successfully bear weight on the joint again.
Patients need to undergo a lengthy physical therapy program in order to restore range of motion and relieve pain and swelling on the joint. Long-term follow-up care will be required in order to maintain the results of this procedure. It is essential for patients to be committed to the specific rehabilitation regimen designed for them as well as to adhere to all instructions provided by their doctor for a successful, long-lasting outcome.