Abstract
Introduction: Navigation systems might enhance the accuracy of ACL replacement.
Methods: The authors used a non image based navigation system with both kinematic and anatomic registration. Navigated aimers were positioned to simulate the intra-articular hole of both femoral and tibial tunnels. The system displayed the position of the guide wire, the expected isometricity of the graft and the potential impingement within the intercondylar notch.
40 patients were operated on for an arthroscopic assisted bone – patellar tendon – bone ACL replacement with an outside-in femoral tunnel. The guide wires were placed according to the standard technique, and their position recorded by the system. The recorded position was compared:
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to the conventional radiographic measurement of the position of the tunnels on plain antero-posterior and lateral X-rays,
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and to the 3D measurement of the position of the tunnels on a CT-scan.
Results: There was a significant difference in the paired absolute values of the mediolateral position of the tibial tunnel between radiographic and navigated measurements (p = 0.008). However there was a significant correlation between these two measurements (p = 0.05).
There was no significant difference in the paired absolute values of the mediolateral position of the tibial tunnel or of the antero-posterior position of the femoral tunnel between radiographic and navigated measurements.
There was no significant difference in the paired absolute values of the antero-posterior and medio-lateral position of the tibial tunnel or of the antero-posterior position of the femoral tunnel between CT and navigated measurements.
Discussion: CT-scan measurement of the positioning of the ACL replacement tunnels is currently the gold standard technique. According to this reference, the antero-posterior position of both the femoral and the tibial tunnels can be accurately assessed by the navigation system used. The X–ray measurement is less accurate and should not be considered as a confident control of the accuracy of the tunnel placement.
Summary: The antero-posterior position of both the femoral and the tibial tunnels can be accurately assessed by the system.
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