Osteochondral autologous transfer surgery, commonly known as OATS, is a surgical procedure used to treat focal cartilage defects in the knee joint. This procedure is often employed when other non-surgical treatments have not provided sufficient relief for the patient's symptoms. Here's an overview of OATS surgery:

• Patient Evaluation: The surgeon evaluates the patient's joint and cartilage damage through physical examination, imaging studies (such as MRI), and arthroscopy if necessary.
• Donor Site Selection: In OATS, the surgeon identifies a healthy area of the patient's own joint (usually a non-weight-bearing region) as the donor site, where a small cylinder or "plug" of cartilage and underlying bone will be harvested.
• Recipient Site Preparation: The damaged area of cartilage and underlying bone in the joint (recipient site) is prepared by removing the damaged tissue and creating a socket to accommodate the cartilage plug.
• Donor Plug Harvest: A cylindrical plug is taken from the chosen donor site, which matches the size and shape of the recipient site. This plug contains both cartilage and subchondral bone.
• Transplantation: The harvested donor plug is then transplanted into the prepared recipient site, ensuring that the cartilage surface aligns with the surrounding joint surface.
• Recovery and Rehabilitation: After the surgery, the patient undergoes a rehabilitation program that includes physical therapy to promote healing, strengthen the joint, and restore function. Weight-bearing and activity restrictions are often imposed to protect the healing joint.

The goal of OATS is to repair the damaged articular cartilage and underlying bone, restoring joint function and alleviating pain. The transplanted plug ideally integrates with the recipient site, eventually forming a new, more durable joint surface. Success rates depend on various factors, including the size and location of the defect, the patient's age, and the rehabilitation process.

OATS is typically used for focal, full-thickness cartilage defects in the knee and other joints. It is most effective when applied to smaller areas of damage. In cases of more extensive cartilage damage or osteoarthritis, other surgical options like microfracture or autologous chondrocyte implantation (ACI) may be considered. Patients should consult with their orthopedic surgeon to determine the most appropriate treatment for their specific condition.