Computational Study on the Effects of Bone Radii and Defect Size on Subchondral Bone Contact

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The Ohio State University

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Articular cartilage defects in the knee can cause pain and discomfort in patients, often limiting their physical ability and leading to osteoarthritis. Fortunately, several surgical options exist to repair the cartilage. To aid in choosing the appropriate surgical procedure, surgeons use an algorithm that places a high significance on the size of the defect, with a defect size of 2 cm2 used as the threshold between microfracture surgery and autograft substitution. This algorithm, however, does not account for variations in the surface curvature of the femur and tibia, which has been found to significantly alter subchondral bone contact (SBC). We hypothesize that bone radii also affect SBC and should be considered in addition to defect size when determining the correct surgery for repair. To test this hypothesis, we developed a finite-element model of the knee with a full-thickness focal defect in the articular cartilage of the femur. This model was validated using experimental data obtained previously in our lab. We then altered tibial and femoral radii, as well as defect size, to determine the threshold at which significant SBC occurs for a given bone radii pair. Results revealed a clear trend of significant SBC occurring at a smaller defect size for smaller bone radii. These results should be confirmed with future experimental testing of various bone radii to determine if current surgical algorithms need to be altered.



knee, cartilage, microfracture, autograft, subchondral