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Avoiding Tunnel Convergence for Posterior Meniscal Root Repair During Anterior Cruciate Ligament Reconstruction

Avoiding Tunnel Convergence for Posterior Meniscal Root Repair During Anterior Cruciate Ligament Reconstruction

Uriel J. Sanchez-Rangel, BS, UNITED STATES Charles M. Chan, MD, UNITED STATES

Stanford University, Palo Alto, California, UNITED STATES


2021 Congress   ePoster Presentation     Not yet rated

 

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Summary: Tunnel convergence can be optimally avoided for medial and lateral meniscus posterior root repair during anterior cruciate (ACL) reconstruction by drilling inferior medial and inferior lateral to the acl tibial tunnel respectively.


Introduction

Injuries to the posterior meniscal root (PMR) can result in altered knee kinematics, contact pressures, and progressive degenerative changes. Repair is recommended through a variety of described techniques often requiring a bone tunnel. This can be challenging in the setting of an anterior cruciate ligament (ACL) reconstruction due to concern for tunnel convergence. In this study, we use computer modeling analysis to describe the relationship of bone tunnels for repair of the medial and lateral PMR in six predefined locations relative to a simulated ACL tibial tunnel to determine optimal tunnel placement configurations to avoid tunnel convergence.

Methods

A mesh model of a human proximal tibia was generated from a magnetic resonance imaging (MRI) based knee atlas (SPL Knee Atlas, Boston, MA) using the 3DSlicer (https://www.slicer.org) exported to Blender (Blender Foundation, Amsterdam, Netherlands) using standardized scripting from the 3DSlicer Script Repository. A simulated 10mm ACL tibial tunnel was then generated and placed within the tibial model relative to standard anatomic landmarks. The footprint of the tibial tunnel on the proximal medial tibial surface was then divided into six quadrants: superior medial (SM), superior lateral (SL), direct medial (DM), direct lateral (DL), inferior medial (IM), inferior lateral(IL). 12 bone tunnels of 3mm diameter simulating posterior root repairs were then generated and placed 3mm from the periphery of the ACL tunnel in each of the 6 quadrants. 6 tunnels were directed towards to the medial PMR while 6 corresponding tunnels were directed toward the lateral PMR. The tunnels were assessed for convergence and measured for minimal inter-tunnel distance relative to the ACL tibial tunnel with the "Measureit" and "Stored Views" add-on tools within Blender per documentation.

Results

Of the 6 tunnels that were directed toward the medial PMR, the SM, DM, IM, and IL tunnels were the only that did not interfere with the ACL tunnel and were at a minimal distance of 0.2mm, 1.90mm, 3.01mm, and 2.62mm away respectively. Of the 6 tunnels that were directed toward the lateral PMR, the DL, IM, and IL tunnels were the only that did not interfere with the ACL tunnel and were at minimal distance of 2.12mm, 3.1mm, and 3.75mm away respectively. The IM and IL tunnels offered the most optimal tunnel trajectory configuration for repairing the medial and lateral PMR respectively while offering greatest distance away from the ACL tibial tunnel.

Conclusion

Bone tunnels for posterior root meniscal repairs can be placed safely in the setting of an ACL reconstruction and adjacent to the ACL tibial tunnel. Arbitrary tunnel placement can lead to tunnel convergence. Placing the tunnel guide inferior medial or inferior lateral to the ACL tibial tunnel offers the greatest inter-tunnel distance and thereby reducing risk for tunnel convergence.


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