How to avoid tunnel convergence during multiple-ligament knee surgery: a practical guide

Background: Multiple ligament knee injuries, often resulting from high-energy trauma or sports-related dislocations, necessitate complex reconstructive procedures to restore joint stability and functional capacity. A significant intraoperative challenge in these cases is tunnel convergence, where the proximity of multiple osseous tunnels increases the risk of hardware collision, compromised graft fixation, impaired biological integration, and potential iatrogenic fractures.

Objective: This article provides a technical guide and 3D mapping strategy to assist surgeons in optimizing tunnel orientation during multiligament reconstructions, including procedures involving the cruciate ligaments, collateral ligaments, and anterolateral structures.

Key Points: In the tibia, the primary risk of confluence occurs between the posterior cruciate ligament (PCL) and posterior oblique ligament (POL) tunnels; directing the POL tunnel 15–20° toward the Gerdy tubercle mitigates this risk. For combined PCL and medial collateral ligament (MCL) reconstructions, angling the tibial MCL tunnel 30° distally prevents convergence. In the femur, lateral condyle tunnels for the fibular collateral ligament and popliteus should be oriented 20–30° anteriorly to avoid the anterior cruciate ligament (ACL) tunnel. On the medial condyle, the MCL and POL tunnels should be angled 30° anteriorly and 30° proximally to maintain adequate bone bridges and avoid the PCL tunnel.

Conclusion: Precise tunnel orientation is the primary modifiable factor for preventing convergence in multiligament knee surgery. Adhering to specific angular guidelines for tibial and femoral drilling reduces the risk of mechanical failure and optimizes the structural integrity of the reconstruction.