The Effect of Graft-Tunnel Diameter Disparity on Intraosseous Healing of the Flexor Tendon Graft in Anterior Cruciate Ligament Reconstruction

Background: Graft-to-tunnel healing is a significant factor in anterior cruciate ligament reconstruction, but there have been few studies on the effect of graft-tunnel diameter disparity on intraosseous healing of the flexor tendon graft. Hypothesis: Graft-tunnel diameter disparity of 2 mm has no effect on the pull-out strength of the graft from the bone tunnel. Study Design: Controlled laboratory study. Methods: Forty-two beagle dogs were divided into three groups. In each animal, reconstruction was performed in the left knee by using a 4-mm diameter autogenous flexor tendon for groups 1 and 2 and by using a 4-mm wide bone-patellar tendon-bone graft in group 3. A 4-mm diameter tunnel was drilled in the tibia of groups 1 and 3 and a 6-mm diameter tunnel, in group 2. In each group, seven animals were sacrificed at 3 and 6 weeks. Results: The perpendicular fibers connecting the graft to the bone were generated in groups 1 and 2, and the number appeared to be higher in group 2, where the space was greater. There was no significant difference in the ultimate failure load between groups 1 and 2 at each period. Conclusion: Graft-tunnel diameter disparity of up to 2 mm may not adversely affect intraosseous healing of the flexor tendon graft. Clinical Relevance: Surgeons need not be overly concerned about minor graft-tunnel diameter disparities.