MRI-based evaluation of tibial tunnel proximity to the anterior horn of the lateral meniscus in remnant-preserving anterior cruciate ligament reconstruction.

Objective: This study aims to evaluate the proximity between the anterior horn of the lateral meniscus (AHLM) and the tibial tunnel on postoperative magnetic resonance imaging (MRI) in patients who underwent remnant-preserving anterior cruciate ligament reconstruction (RP-ACLR), in order to assess the potential risk of AHLM injury. Methods: Eighty patients who underwent RP-ACLR between 2014 and 2020 were retrospectively analysed using postoperative MRIs. A 4-layer hamstring graft was used in all cases, and the mean diameter of the tibial tunnel was 8.17 ± 0.67 mm (range: 7-10 mm). The nearest distances between the AHLM and the tibial tunnel were measured in the coronal and axial planes on postoperative MRIs. Pearson and Spearman correlation tests were used for the correlation analyses. Calculations were made for the intraclass and interclass correlation coe!cients (ICC). Results: In the axial plane, the tibial tunnel was tangential to the AHLM in 4 patients (5%) and in the coronal plane in 3 patients (3.8%), with the nearest distance measured as 0 mm. No contour irregularity of the lateral meniscus was observed in any patient; meniscal morphology and signal characteristics were preserved, and no complex tears, deformations, or extrusions were detected on MRI. Statistical analyses demonstrated excellent intraobserver (ICC: 0.97-0.98) and interobserver (ICC: 0.99) reliability of the measurement method. Additionally, no statistically significant correlation was found between the measured distances and Lysholm scores. Conclusion: This study demonstrated that, although the tibial tunnel in RP-ACLR is in close proximity to the AHLM, injury to the AHLM can be avoided by carefully adjusting the trajectory of the guide wire to ensure it exits through the centre of the remnant tissue. Level of Evidence: Level IV, Therapeutic Study.