Paper 17: Optimal Tibial Tunnel Placement for Medial and Lateral Meniscal Root Repair in the Setting of Multiligament Reconstructions of the Knee

Abstract

Objectives:Although the risk of tibial tunnel convergence in the setting of multiligament reconstruction has been reported in the literature, the risk of tunnel convergence in the setting of posterior cruciate ligament (PCL), anterior cruciate ligament (ACL), and medial and lateral meniscal root repair has not been defined. The purpose of this study was to examine the risk of tunnel convergence and to determine optimal tunnel placement for ACL and PCL reconstruction performed in conjunction with posterior medial and lateral meniscal root repairs in the proximal tibia.Methods:Three-dimensional tibial models were created using computed tomography scans of twenty cadaveric specimens. After determining optimal tunnel entry and exit points for ACL and PCL reconstructions, and medial and lateral meniscal root repair on the models, Mimics software was used to create root tunnels. The meniscal root repair tunnels were then re-oriented to be parallel to the ACL tunnel. The initial and re-oriented configurations are illustrated in Figure 1. Tunnel convergence risk was analyzed with single and double tunnel techniques in both case scenarios.Results:There were no cases of convergence between the ACL and medial meniscal root tunnels in any of the configurations. The greatest distance between the tunnels was achieved with the single tunnel technique in parallel orientation (12.09 ± 2.78 mm). All specimens demonstrated convergence between the ACL and lateral meniscal root tunnels when the sagittal plane entry was not taken into consideration and only the anatomic root attachment was accounted for, for single and double tunnel techniques, but no convergence was seen between these tunnels with the parallel orientation in the sagittal plane. Figure 2 illustrates the reduction in the convergence risk when the meniscal root tunnels are reoriented as parallel to the ACL tunnel. There were no cases of convergence between the PCL and medial meniscal root tunnels in the original orientation, but 2/20 specimens demonstrated convergence in the parallel orientation with the double tunnel technique and no cases of convergence in the single tunnel technique. The PCL and lateral meniscal root tunnels did not demonstrate convergence in any configuration. Table 1 demonstrates the mean, minimum and maximum distances of each tunnel configuration as well as the number of cases where the distance between tunnels was <2mm. A summary of the preferred tunnel configurations for each setting, ranked by greatest tunnel distance conferred and cases of convergence, is reported in Table 2.Conclusions:There is a high risk of convergence between ACL and posterior meniscus root tunnels. Re-orienting meniscal root tunnels parallel to ACL tunnels may help reduce this risk. When PCL reconstruction is performed with ACL reconstruction and medial and lateral meniscal root repair, the single tunnel root repair technique may pose less risk over the double tunnel technique to prevent tunnel convergence between the meniscal root repair and PCL tunnels in the tibia.Figure 1. Illustration of the reconstruction of the tunnels. (A) Initial orientation where the meniscal root tunnels’ entry points on the anteromedial aspect of the tibia were created above the ACL tunnel. (B) The meniscal root tunnels re-orientated and were placed parallel to that of the ACL and aimed to exit at the anatomic attachment of the posterior roots of the meniscus. (Gold guide for the creation of the ACL tunnel and silver guide for the creation of the meniscal root tunnel)