OSTEOCHONDRAL AUTOGRAFT TRANSFER (OATS)
The ends of the femur, tibia, and undersurface of the patella (kneecap), the knee bones, are capped with a smooth surface, which is called articular cartilage. Cartilage protects the ends of bone; it can withstand a significant amount of impact and is significantly smoother than ice, which allows smooth motion in the knee joint. An articular cartilage injury (or “chondral” injury), may occur following a twisting injury to the knee, a direct blow to the knee, or wear and tear as a one ages. Some patients with cartilage injuries also injure the bone underneath the cartilage. This type of injury is called an “osteochondral defect.” Many patients can be treated successfully with a combination of activity modification and other non-surgical options, such as a focused physical therapy program. Other patients with persistent symptoms or larger defects may require surgery.
In those patients with a damaged area of bone and cartilage who require surgery, Dr. Keller may recommend transferring healthy cartilage and bone from another area of the patient’s knee to the damaged area. This procedure is called osteochondral autograft transfer (OATS). During an OATS procedure, Dr. Keller uses a minimally-invasive technique with an arthroscope (surgical camera) and first cleans the damaged area of cartilage and bone. Next, Dr. Keller uses a surgical device to remove a plug of healthy bone and cartilage from another area of the patient’s knee where the patient does not bear weight. Dr. Keller is careful to match the size of the donor bone/cartilage unit to the area of damaged bone and cartilage. The donor bone/cartilage unit is then implanted into the area of damaged bone/cartilage with a surgical device, similar to filling a pothole.
Following surgery, patients are placed in a hinged brace that is locked straight. Dr. Keller recommends no weight-bearing or partial weight-bearing for 4-6 weeks in the brace. When the patient is sitting or lying down, Dr. Keller encourages knee range of motion exercises with the brace removed. Dr. Keller also recommends intermittent icing and straight leg raises to strengthen the quadriceps muscles. Dr. Keller recommends starting formal physical therapy one week after surgery. Physical therapy focuses on reducing swelling in the knee, restoring full range of motion, and eventually, restoring strength to the knee. Most patients can start full weight bearing on the affected leg six weeks after surgery, depending on the location of the defect. Most patients start cutting activities and sporting activity approximately 4-6 months after surgery.