3D-Printed Patient-Specific Guides Reduce Femoral Tunnel Convergence in Anatomic Knee Multiligament Reconstruction:...

Multiligament knee reconstruction is a technically demanding procedure with a steep learning curve and carries the potential for significant complications if technical accuracy is not achieved. Although optimal tunnel trajectories to prevent convergence have been described, it remains unclear how accurately these theoretical trajectories are executed in practice and whether patient-specific guides can improve precision and reduce tunnel convergence.

To evaluate the effectiveness of patient-specific guides in preventing tunnel convergence and improving surgical accuracy in multiligament knee reconstruction.

Controlled laboratory study.

Computed tomography scans from a single case were used to create accurate 3-dimensionally printed femur models. Each of the 8 participating orthopaedic surgeons performed tunnel placement on 2 models: 1 using the freehand technique and 1 using a custom-designed guide. Tunnels of the anterior cruciate ligament (single bundle) and posterior cruciate ligament (double bundle consisting of the anterolateral and posteromedial bundles) were constant. Surgeons created femoral tunnels for posterolateral structures (fibular collateral ligament, popliteus tendon) and posteromedial structures (medial collateral ligament, posterior oblique ligament). Postprocedure computed tomography was used to assess tunnel convergence, intertunnel distances (>2 mm defined as safe), and tunnel entry accuracy.

Lateral tunnel convergence occurred in 11 of 16 tunnels via freehand-primarily between the popliteus tendon and anterior cruciate ligament (7/8)-and none of the patient-specific guide models (0/16; P = .001). Medial convergence was reduced from 10 of 16 via freehand to 2 of 16 via the guide (P = .001), most commonly between the posterior oblique ligament and posterior cruciate ligament-posteromedial bundle. Mean intertunnel distances were significantly greater via the guide. Tunnel entry accuracy was 100% with the guide.

The use of patient-specific guides significantly reduces tunnel convergence and improves tunnel entry point precision in multiligament reconstruction simulation. Freehand tunneling highlights the prominent influence of human error.

Surgical success in multiligament reconstruction relies on anatomic graft function, yet tunnel convergence may jeopardize graft integrity and lead to failure. Therefore, avoiding tunnel convergence is of utmost importance for a successful reconstruction.