The Effect of ACL Femoral Drilling on Posterolateral Corner Reconstruction

Purpose: This study aimed to evaluate the risk of tunnel collision with combined posterolateral corner (PLC) and anterior cruciate ligament (ACL) reconstruction and to identify which technique reduces the risk of tunnel collision. Methods: LCL and popliteus tunnels were drilled in sixty-four medium and large synthetic femurs and sixteen synthetic knee joints. ACL tunnels were then drilled using four different techniques: transtibial, anteromedial portal with a rigid guide pin, anteromedial portal with a flexible guide pin, and outside-in. The samples without obvious tunnel collision then underwent CT scan with 2-mm slices to determine the closest distance between the tunnels and the tangential distance (mm) between them were recorded. Results: Overall frequency of tunnel collision was 24/32 (75%) in large femur specimens and 32/32 (100%) for medium femur specimens. Obvious tunnel collision was observed in all transtibial, anteromedial with flexible instruments, and anteromedial with rigid instruments regardless of femur size or side. All of the specimens without tunnel collision occurred in the large femurs from the outside in group (n=8). The mean tunnel separation in all samples was 1.93 mm, with a range of 1.06 mm to 2.54 mm. Conclusion: Consistent with previous studies, we found a high rate of collision, especially in medium size femurs. The results of our study have provided evidence for the use of outside-in ACL reconstruction and PLC with 2 lateral femoral tunnels with the least amount of collision risk.