Intertunnel Relationships in the Tibia During Reconstruction of Multiple Knee Ligaments: How to Avoid Tunnel Convergence.

BACKGROUND

Knee dislocations are rare but potentially devastating injuries, often involving tears of multiple knee ligaments. Several studies have reported improved clinical and functional outcomes with surgical management of torn knee ligaments compared with nonsurgical management. Most multiple ligament reconstruction techniques involve creating several tunnels for various reconstruction grafts, posing a risk of tunnel convergence in the proximal tibia.

PURPOSE

To assess the risk of tunnel convergence and determine the optimal tunnel placement for the reconstruction of multiple ligaments in the tibia.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Three-dimensional knee models were developed using customized software from computed tomography images of 21 patients. Mimics software was used to create tunnels for each of the 4 primary ligamentous structures, replicating a surgical approach that would be used in actual multiple ligament reconstruction surgery. The tunnel orientation was varied in anatomically relevant directions to find orientations that did not result in tunnel convergence.

RESULTS

There was a high risk of tunnel convergence (66.7%) between the posterior cruciate ligament (PCL) and posterior oblique ligament (POL) tunnels when the POL tunnel was aimed toward the Gerdy tubercle as suggested in the literature. No tunnel convergence was observed when the POL tunnel was aimed 15 mm medial to the Gerdy tubercle. No tunnel convergence was observed between the anterior cruciate ligament (ACL) and POL. Tunnel convergence was observed between the PCL and superficial medial collateral ligament (sMCL) in 19.0% of cases when the sMCL tunnel was aimed transversely across the tibia. Aiming the sMCL tunnel transversely and directing 30° distally significantly increased the mean distance between the sMCL and PCL to 6.9 mm (P < .001), and no tunnel convergence was observed. No tunnel convergence was observed between the PCL and posterolateral corner tunnels or between the ACL and PCL tunnels.

CONCLUSION

There is a high risk of tunnel convergence in the proximal tibia during the reconstruction of multiple knee ligaments. Aiming the POL tunnel 15 mm medial to the Gerdy tubercle and the sMCL tunnel transversely across the tibia (anterior to the fibula) and 30° distal to the horizontal plane reduces the risk of tunnel convergence.

CLINICAL RELEVANCE

The tunnel orientation of the POL and sMCL on the tibia should be adjusted to avoid convergence with the PCL tunnel during multiple ligament knee reconstruction.