2017 ISAKOS Biennial Congress ePoster #1821

 

Multiple Ligament Reconstruction Femoral Tunnels: Inter-Tunnel Relationships And Guidelines To Avoid Convergence

Gilbert Moatshe, MD, PhD, Oslo NORWAY
Alex Brady, MSc, Vail, CO UNITED STATES
Erik Slette, BA, Vail UNITED STATES
Jorge Chahla, MD, PhD, Chicago, IL UNITED STATES
Travis Lee Turnbull, PhD, Vail, CO UNITED STATES
Lars Engebretsen, MD, PhD, Oslo/Lausanne NORWAY
Robert F. LaPrade, MD, PhD, Chanhassen, MN UNITED STATES

Steadman Philippon Research Institute, Vail, Colorado, UNITED STATES

FDA Status Not Applicable

Summary

There is a high risk of tunnel convergence during multilligament knee reconstructions. Femoral tunnel orientations during multiple ligament reconstructions need to be adjusted to avoid tunnel convergence.

Abstract

Background

Knee dislocations often require multiple concurrent ligament reconstructions, which involve creating several tunnels in the distal femur. Therefore, the risk of tunnel convergence is increased due to the limited bone volume within the distal aspect of the femur.

Purpose

To assess the risk of tunnel convergence and determine the optimal reconstruction tunnel orientations for multiple ligament reconstructions in the femur.

Study Design: Descriptive Laboratory Study

Methods

Three-dimensional knee models were developed from computed tomography images of 21 patients. Medical image processing software was used to create tunnels for each of the primary ligamentous structures, replicating a surgical approach that would be used in a multiple ligament reconstruction surgery. Thereafter, tunnel orientation was varied in surgically relevant directions to determine orientations that minimized the risk of tunnel convergence.

Results

A high risk of tunnel convergence was observed between the FCL and ACL tunnels when the FCL tunnel was aimed at 0 in the axial and coronal planes. Aiming the FCL tunnel 35 anteriorly minimized convergence with the ACL tunnel. No tunnel convergence was observed for the popliteus tunnel aimed 35 anteriorly and parallel to the FCL tunnel. To avoid convergence between the sMCL and PCL tunnels, the sMCL tunnels should be aimed 40 proximally in the coronal plane and 20–40 anteriorly. During a concomitant POL reconstruction, the sMCL should be aimed 40 proximally and anteriorly, and the POL 20 proximally and anteriorly. The popliteus and POL tunnels aimed at 0 in both the coronal and axial planes had increased risk of violating the intercondylar notch.

Conclusion

Femoral tunnel orientations during multiple ligament reconstructions need to be adjusted to avoid tunnel convergence. On the lateral side, aiming the FCL and popliteus tunnels 35 anteriorly eliminated convergence with the ACL tunnel. On the medial side, convergence was avoided by orienting the sMCL tunnel 40 proximally and anteriorly and the POL tunnel 20 proximally and anteriorly. The POL and popliteus tunnels aimed at 0 in the axial plane had an increased risk of violating the intercondylar notch.

Clinical Relevance: The risk of tunnel convergence with the ACL and PCL femoral tunnels can be reduced by adjusting the orientation of the FCL and popliteus tunnels, and the sMCL and POL tunnels, respectively.

Keywords: Multiple ligament reconstruction, knee, femur, tunnel orientation, tunnel convergence