Two techniques for anterior cruciate ligament tibial fixation with a bicortical screw: an in vitro study of neurovascular risk.

We compared the distance to neurovascular structures between exit holes for screws drilled toward the fibula in a medial to lateral orientation (16 cadaveric knees; experimental group) versus screws drilled the standard way, perpendicular to the cortex of the proximal tibial metaphysis (19 cadaveric knees; control group). A bicortical screw was used for tibial fixation, specimens were dissected, and the major neurovascular structures were identified. The screw exit hole on the posterior tibial cortex was found, and a fine caliper was used to measure distances from the hole to the neurovascular structures. The 2 groups differed significantly in distances to the popliteal bifurcation (mean difference, 6.8 mm; P = .019), the anterior tibial vein (mean difference, 9.7 mm; P<.001), and the anterior tibial artery (mean difference, 10.9 mm; P<.001), with the distances larger in the experimental group. There was 1 tibial artery injury in the control group. The groups did not differ significantly with regard to distances to the common peroneal nerve and the tibial nerve (P>.05). During bicortical screw placement in the proximal-medial tibial metaphysis, aiming toward the fibula significantly reduces the risk for vascular injury, as evidenced by there being no injuries, increased distances, and increased margin of safety from vascular structures.