The Lateral Meniscus as a Guide to Anatomical Tibial Tunnel Placement During Anterior Cruciate Ligament Reconstruction

Abstract

Purpose: The aim of the study is to show, on an MRI scan, that the posterior border of the anterior horn of the lateral meniscus (AHLM) could guide tibial tunnel position in the sagittal plane and provide anatomical graft position.Method:One hundred MRI scans were analysed with normal cruciate ligaments and no evidence of meniscal injury. We measured the distance between the posterior border of the AHLM and the midpoint of the ACL by superimposing sagittal images.Results:The mean distance between the posterior border of the AHLM and the ACL midpoint was -0.1mm (i.e. 0.1mm posterior to the ACL midpoint). The range was 5mm to -4.6mm. The median value was 0.0mm. 95% confidence interval was from -0.5 to 0.3mm. A normal, parametric distribution was observed and Intra- and inter-observer variability showed significant correlation (p<0.05) using Pearsons Correlation test (intra-observer) and Interclass correlation (inter-observer).Conclusion:Using the posterior border of the AHLM is a reproducible and anatomical marker for the midpoint of the ACL footprint in the majority of cases. It can be used intra-operatively as a guide for tibial tunnel insertion and graft placement allowing anatomical reconstruction. There will inevitably be some anatomical variation. Pre-operative MRI assessment of the relationship between AHLM and ACL footprint is advised to improve surgical planning.Level of Evidence:Level 4.

Evaluating the Accuracy of Tibial Tunnel Placement After Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction

“…Using the root ligament of the AHLM as a radiologic reference point on MRI is supported in the literature, which describes this structure as being a reliable and reproducible landmark. 10 Kassam et al 10 recently demonstrated that the ACL tibial footprint was on average 0.1 mm anterior to the posterior border of the AHLM. Zantop et al 27 showed that the center of the AM bundle is aligned with the AHLM in cadaveric specimens.…”

“…The reference point chosen was the center point of the root ligament of the AHLM, which is a reproducible landmark and easily visualized on axial and sagittal plane MRI. 10 For the ACL footprint, we identified the center point of the entire ACL footprint, which included both the anteromedial (AM) and posterolateral (PL) bundles. Next, we superimposed both axial images and measured the distance from the center point of the ACL footprint to the center point of the root ligament of the AHLM in the coronal (medial-lateral) and sagittal (anterior-posterior) planes (see Figure 1).…”

“…A misplaced graft can lead to notch impingement or shortening of the overall length of the graft. 9,10…”

“…3,16,18,19,26 Nevertheless, improper surgical technique continues to be a leading cause of failure of ACL surgery. 1,10,16,23 Among these technical errors is graft malpositioning. 5,23 The ideal position of the femoral tunnel has been heavily scrutinized in the literature owing to the difficulty in reapproximating the avulsed ACL footprint on the lateral femoral condyle.…”

Anatomic Anterior Cruciate Ligament Reconstruction: The Use of the Anterior Horn of the Lateral Meniscus as a Guide to Tibial Tunnel Placement

“…The PBAHLM can be up to 5 mm from the center of the ACL footprint; thus careful correlation of the position of the PBAHLM and the center of the ACL footprint is recommended preoperatively, on an MRI scan, and intraoperatively to ensure the tibial tunnel is placed in an anatomic position. 9 Consideration must be taken when the planned position of the tunnel is too anterior and a surgical decision needs to be made to avoid tunnel placement too anteriorly to prevent graft impingement. Preoperatively, the position of the PBAHLM should be assessed in relation to the center of the ACL footprint on an MRI scan.…”