Evaluation of intraoperative anterior cruciate ligament laxity using a navigation system in the anatomical single bundle reconstruction

Purpose The anatomical anterior cruciate ligament (ACL) reconstruction attempts to, by reproducing the natural orientation of its fibres, achieve a better rotational stability of the knee. The aim of this paper is to quantify the anteroposterior and rotational laxity of the knee before and after an anatomic ligamentoplasty using the Orthopilot ® navigation system as a supporting tool. Material and method We describe the distinctive steps of Orthopilot ® navigation as well as conducting a retrospective cross-sectional study on a cohort of 20 patients operated in our hospital for chronic primary ACL rupture from January 2010 to May 2011. The precise location of the tunnels was defined with the help of the navigator and the intra-articular landmarks and stability tests were performed in both the sagittal and axial planes. Results In our technique for anatomical ACL reconstruction placed the tibial tunnel at a mean distance of 16.8 ± 4.92 mm from the posterior cruciate ligament in a position that represented 44.1 ± 4.35% of the total width of the tibial plateau. The average distance from the centre of the femoral tunnel to the posterior cortex of the lateral condyle was 7.89 ± 2.78 mm. Intra-operatively and before ACL reconstruction, the mean (±SD) anteroposterior movement, internal rotation and external rotation of the tibia at 30° position were 15.5 mm (±5.11), 19° (±3.62) and 19.65° (±3.26), respectively. After reconstruction these values decreased to 5.6 mm (±1.72°), 12.17° (±3.76) and 16.9° (±4.42), respectively. Conclusions The use of navigation systems supporting the surgery allows the systematic positioning of bone tunnels and standardises the procedures for the desired reconstruction. ACL reconstruction using the technique described, improves the anteroposterior and rotational stability compared to preoperative status, to a stability state that could be considered physiological according to current scientific knowledge.