The objective of this study was to validate the technique used to measure anterior tibial translation in cadaver knees using the GNRB^® device by comparing it with the gold standard, the OrthoPilot^® navigation system.

Simultaneous measurement of anterior tibial translation by the GNRB^® and the OrthoPilot^® in the chosen experimental conditions will result in significant differences between devices.

Five fresh frozen cadavers were used. The knee was placed in 20° flexion. Four calibrated posterior-anterior forces (134N to 250N) were applied. For each applied force, the anterior tibial translation was measured simultaneously by both devices. Two conditions were analyzed: anterior cruciate ligament (ACL) intact and ACL transected. The primary criterion was anterior tibial translation at 250N. The measurements were compared using a paired Student's t-test and the correlation coefficient was calculated. Agreement between the two methods was determined using Bland-Altman plots. Consistency of the measurements was determined by calculating the intraclass correlation coefficient.

For all applied forces and ligament conditions, the mean difference between the GNRB^® and the navigation system was 0.1±1.7mm (n.s). Out of the 80 measurements taken, the difference between devices was less than ±2mm in 66 cases (82%). There was a strong correlation, good agreement and high consistency between the two measurement methods.

The differences between the measurements taken by the GNRB^® and the navigation system were small and likely have no clinical impact. We recommend using the GNRB^® to evaluate anterior knee laxity.

II controlled laboratory study.