Lateral Femoral Cortical Breach During Anterior Cruciate Ligament Reconstruction: A Biomechanical Analysis

PurposeThe purpose of our study was to determine whether secondary fixation is needed when lateral femoral wall breach occurs and whether the diameter of the femoral tunnel affects the cyclical and ultimate load to failure of 3 different suspensory fixation devices.MethodsSixty fresh-frozen porcine femora were dissected to isolate the anterior cruciate ligament (ACL) footprint. Femoral ACL tunnels were then drilled at diameters of 7, 8, 9, and 10 mm. We conducted 5 separate cyclical and ultimate load testing trials, at each tunnel diameter, for 3 different cortical suspension devices.ResultsThe mean load to failure decreased as the tunnel size enlarged for all 3 devices. In 7-mm tunnels, mean failure load ranged from 1,163.7 to 1,455.0 N across the 3 devices; in 8-mm tunnels, 1,154.7 to 1,643.2 N; in 9-mm tunnels, 820.8 to 1,125.21 N; and in 10-mm tunnels, 314.7 to 917.8 N. Modes of failure also varied as the tunnel sizes enlarged. The ultimate load was not different among the 3 manufacturers (P = .08), but there was a difference in the ultimate load across the 4 tunnel diameters (P < .05), except when we compared the 7-mm tunnel with the 8-mm tunnel (P = .91).ConclusionsWith 7- and 8-mm-diameter tunnels, failure loads with each of the suspensory devices tested exceeded the documented interference screw load to failure.Clinical RelevanceOur findings suggest that, for soft-tissue ACL grafts, femoral tunnels of 8 mm or less can be drilled through the lateral femoral cortex while still using a suspensory device for graft fixation. With pediatric, double-bundle, and anatomic ACL reconstructions, smaller and shorter tunnels are routinely used. Thus, breaching the lateral cortex when using suspensory fixation may increase tunnel length while still achieving stable fixation.