Osteochondral autograft transfer system (OATS) ( also known as mosaicplasty) is a surgical procedure in which damaged areas of weight bearing articular cartilage are replaced by healthy cartilage from non-weight bearing sites in the same knee.
It is done in patients below the age of 50 years in which there is damage to a small area of cartilage, usually limited to 10-20 mm in size e.g. a small traumatic ulcer. It is not a treatment of knee osteoarthritis.
How is the procedure done:
- An arthroscope is used to visualized the ulcer and evaluate the condition of the rest of the knee. Any cartilage remnant over the ulcer is removed exposing the underlying bone.
- Drill holes are made in the underlying bone
- The drill holes are made vertical to the surface of the joint
- A special hollow sharp tube is used to obtain cylindrical plugs containing bone covered by cartilage. These are taken from non-weight bearing areas of the knee joint.
- The plugs are pushed in the drill holes previously drilled in the ulcer.
- Thus, the ulcer become filled with normal articular cartilage.