The OATS Procedure

The OATS procedure, an abbreviation for osteoarticular transfer system, is a surgical procedure used to treat focal cartilage defects. OATS is one technique of several used to treat this problem; the type of procedure is called a mosaicplasty.

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. This 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 - 20 mm in size. This type of damage is usually seen in younger patients (less than 50 years old) who experience trauma to their joint.

When Is the OATS Procedure Done?

Often the surgeon will consider this type of procedure, 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 areas of the joint where the body can do without the cartilage, and these are moved to the damaged area of the joint. The Arthrex corporation has a registered trademark for the OATS Osteochondral Autograft Transfer System.

How Successful Is the OATS Procedure?

A study of 96 patients compared the OATS procedure to microfracture treatment for isolated articular cartilage defects of the knee. The patients were on average 30-32 years old and were followed yearly for five years after surgery. They found similar general health and knee function outcomes for both procedures. But there was a difference in being able to maintain a superior level of athletic activity, with OAT mosaicplasty being better than microfracture.

How the OATS Procedure Is Done

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.

Now 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 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.

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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 .