OATS procedure is indicated for defects of what size?

• A. 0.5 square cm
• B. 1.0 square cm
• C. 2.0 square cm
• D. 1.5 square cm

Answer: (D)

OATS is used for focal osteochondral defects where you need to replace a small, contained area of damaged cartilage with autograft plugs. The key limitation is lesion size: you must harvest enough osteochondral plugs from a donor site and still maintain a smooth, congruent joint surface. In the talus (a common site for OATS in the foot and ankle), this approach is most practical for defects up to about 1.5 cm². Lesions of this size can be filled with a reasonable number of plugs to restore contour without causing excessive donor-site morbidity or a rough articular surface. Larger defects would require many plugs and increase the risk of incongruity and donor-site problems, making alternative treatments more appropriate. Therefore, 1.5 cm² is the most fitting indication size for the OATS procedure.