Neurovascular risk of bicortical tibial drilling for screw and spiked washer fixation of soft-tissue anterior cruciate ligament graft

Purpose: As the use of soft-tissue anterior cruciate ligament (ACL) grafts, including hamstrings grafts, has become more prominent and the benefits of aggressive rehabilitation have become clear, maximizing fixation with scre w and spiked washers is important. Bicortical fixation may be superior. We were concerned about potential neurovascular risks and designed this study to define the posterior neurovasculature structures at risk when drilling f or bicortical tibial screw fixation during ACL reconstruction. Type of Stud y: Consecutive sample. Methods: We placed the tibial tunnel arthroscopicall y in 10 cadaveric knees using a standard tibial drill guide. Accurate tibia l tunnel position was documented in each knee by lateral radiograph. A 4.5- mm bicortical drill hole was placed perpendicular to the tibial surface 1 c m distal to the tibial tunnel. The distances from the posterior tibial dril l exit point to nearby neurovascular structures were measured with a calipe r. Results: The closest structure to the exit point was the bifurcation of the popliteal artery/vein (11.4 +/- 0.6 mm; range, 8.4 to 14.0 mm). The nex t closest was the anterior tibial vein (11.7 +/- 1.6 mm; range, 3.5 to 22.8 mm). The closest any individual hole came to a neurovascular structure was 3.5 mm from the anterior tibial vein. Conclusions: Bicortical drilling for fixation of soft tissue grafts appears reasonably safe. The structures at greatest risk for injury are the bifurcation of the popliteal artery/vein a nd the anterior tibial vein.