The OATS Procedure

The OATS (osteoarticular transfer system) procedure is a type of surgical procedure called mosaicplasty that is used to treat a knee injury called focal cartilage defects. OATS is one technique of several used to treat this problem.

male doctor examining female patient's leg
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A mosaicplasty uses cartilage from undamaged areas of the joint and moves this cartilage to a damaged area. This type of procedure is only useful for the treatment of focal cartilage damage, which means the widespread damage of cartilage seen in conditions like osteoarthritis cannot be treated with mosaicplasty. This treatment is only used for isolated areas of cartilage damage, usually limited to 10 millimeters to 20 millimeters in size. This type of damage is typically seen in patients younger than 50 years old who experience trauma to their joint.

When Is the OATS Procedure Performed?

The OATS procedure is fairly common, but if X-rays or arthroscopic examination show evidence of more widespread cartilage damage, the OATS procedure will not be performed. The reason is that the OATS procedure will not benefit these patients.

The OATS procedure, developed by the Arthrex corporation, is one type of mosaicplasty. Small "plugs" of cartilage are removed from healthy areas of the joint and moved to damaged areas of the joint. The Arthrex corporation has a registered trademark for the OATS Osteochondral Autograft Transfer System.

How Successful Is the OATS Procedure?

One study of 96 patients compared the OATS procedure to another knee procedure called microfracture treatment for isolated articular cartilage defects. The patients were on average 30–32 years old and were followed yearly for five years after surgery. Researchers found similar general health and knee function outcomes for both procedures. However, patients undergoing OATS mosiacplasty were able to maintain a superior level of athletic activity afterward than those who had the microfracture procedure.

How the OATS Procedure Is Performed

The Single Use OATS (Osteochondral Autograft Transfer System) developed by Arthrex is used in this surgical procedure. The surgical kit includes a recipient harvester, donor harvester, alignment rod, tamp, graft delivery tube, and core extruder.

The patient is both the donor and the recipient, with healthy cartilage and its underlying bone harvested from a nearby area of the joint to be transplanted into the area that has a cartilage defect. The OATS donor harvester is positioned on the donor surface and struck with a mallet until it has been tamped 15 millimeters into the donor surface. The handle is then rotated to harvest the core and withdrawn.

Then a socket is made on the surface that had the focal cartilage defect that will be the right size to receive the plug. A recipient harvester is hammered in and twisted to remove a plug to make the right size and depth of the hole. An alignment rod is used to measure the depth and any needed adjustments are made to prepare it for the transplant graft.

Once it is ready, the graft delivery tube is placed at the lip of the recipient socket and extruded (forced) into it. A tamp is then tapped to seat the graft in the socket. The surgeon may fill the donor sites with hydroxyapatite rods and may use biological glues to seal the recipient socket.

3 Sources
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  1. International Cartilage Regeneration and Joint Preservation Society. Mosaicplasty.

  2. Arthrex: Single Use OATS (Osteochondral Autograft Transfer System) Surgical Technique 403, 2013.

  3. Aaron J. Krych, MD; Heather W. Harnly, MD; Scott A. Rodeo, MD; Riley J. Williams III, MD. "Activity Levels Are Higher After Osteochondral Autograft Transfer Mosaicplasty Than After Microfracture for Articular Cartilage Defects of the Knee A Retrospective Comparative Study." J Bone Joint Surg Am, 2012 Jun 06; 94 (11): 971 -978 .

By Jonathan Cluett, MD
Jonathan Cluett, MD, is board-certified in orthopedic surgery. He served as assistant team physician to Chivas USA (Major League Soccer) and the United States men's and women's national soccer teams.