Our joints are lined with a smooth, tough substance called cartilage. This surface helps joints glide smoothly and without pain, providing us the flexibility to move. As we age or engage in sports, this cartilage will begin to break down and can become damaged. Certain conditions can develop as a result of this occurrence, leading to pain, stiffness, and swelling of the knee joint.
Description of Osteochondral Autograft Transfers
One specific cartilage restoration procedure that has proven to bring patients relief, is an osteochondral autograft transfer (OATS), which involves harvesting and transferring a plug of bone and cartilage from a lesser weight-bearing area of the knee with a cylindrical coring device to an area of the knee where there is a symptomatic osteochondral defect. This procedure is usually performed arthroscopically. In general, these areas should be approximately 1 cm in size or less to minimize donor site morbidity from the area that the plug was transferred from.
While we generally recommend microfractures to treat small defects such as this, there are times when a microfracture may not be indicated. This may include patients who are on blood thinners, who have a cyst below the area of the cartilage defect, or workers/participants in sports who need a quicker return to activities after surgery.
Most of the time, a small open incision is made at the area where the plug is being placed to make sure it is purely perpendicular and restoring the normal of contour of the remaining articular cartilage. While most of the surgery can be performed arthroscopically, it does require several arthroscopic incisions around the knee to place the donor graft into the recipient’s site. Most surgeons who perform a large number of these procedures utilized this technique.
The patients who undergo osteochondral autograft transfers are usually non-weight-bearing for 6 weeks and use a continuous passive motion ( CPM) machine for 6-8 hours a day as part of their rehabilitation during the time that they are non-weight-bearing. At 6 weeks postoperatively, they are permitted to increase their weight-bearing as tolerated, start the use of a stationary bike, and increase their overall activity levels. In general, we recommend that the patient not return to full activities until their strength has returned, they have no swelling or pain with activities, and their overall function has returned back to normal. This usually takes anywhere from 5-6 months at a minimum.