Anatomic Transtibial Tunnel Placement Using an Initial 6-mm Drill Bit for Anterior Cruciate Ligament Reconstruction

Precise anatomic tunnel placement is essential for restoring native knee biomechanics and minimizing graft failure in anterior cruciate ligament reconstruction. We describe a tibial tunnel drilling technique designed to enhance tunnel placement accuracy, reduce intra-articular trauma, and preserve native tibial footprint remnants when indicated. Following standard arthroscopic visualization, tibial and femoral tunnel positioning is guided by established anatomic landmarks. Using a tibial guide, a guidewire is initially placed at the intended tibial site. If positioning is suboptimal, a 6-mm tunnel is created, which provides a controlled working corridor for subsequent guidewire relocation within its margins. This step enables adjustment of tunnel trajectory with high precision. A definitive 10-mm tunnel is then drilled at the corrected location. Notably, expansion from a 6- to 10-mm tunnel using this technique only increases the overall cross-sectional tunnel area within the tibia by ~5%, thereby maintaining bone stock and minimizing damage. This technique offers a reproducible method to refine tibial tunnel placement while mitigating the risks associated with repeated drilling and excessive tunnel enlargement.