OATS is an abbreviation for a procedure where a core of healthy cartilage and bone is taken from an unimportant area of the knee to replace a more important damaged area.

Page updated January 2024 by Dr Sheila Strover (Clinical Editor)


A chondral defect in an important part of the joint.

OATS in place

A plug of healthy bone and cartilage is taken from elsewhere in the body and press-fitted into the defect, where it will heal.


What does OATS stand for?

OATS stands for 'Osteochondral Autograft Transfer System' - which means a bit of joint cartilage and underlying bone is taken from the patient and transferred from a relatively unimportant healthy bit of the joint to replace a damaged area in a more important area.

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Indications for OATS

The OATS procedure is indicated in the younger symptomatic patient who has a chondral defect of 2 cm or less on the condyle of the femur, and who has other surgical and conservative efforts to relieve symptoms, and where other factors are normal such as the mechanical alignment, and there are no problems with the ligaments or menisci.

By transferring a core of healthy cartilage together with the underlying bone, the area should heal well and be covered by true cartilage, rather than fibroscartilage, which often is the result of other repair procedures such as ACI.

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What sort of rehabilitation is required after OATS surgery?

For the first three weeks after surgery the patient needs to be non-weight-bearing. From weeks 4-6 toe touchdown is allowed but weight-bearing is limited to 25% of the body weight of the patient, measured by the physiotherapist.

During these 6 weeks a locked extension brace is worn to limit the knee range of motion while ambulating and prevent any displacement of the graft.

This is a useful reference.

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Forum discussions

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Peer-reviewed papers

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Osteoarticular transfer system
Osteochondral Autograft Transfer System
Osteochondral Autologous Transfer System

Dr Sheila Strover (Editor)
BSc (Hons), MB BCh, MBA

See biography...