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Experimental validation of the GNRB® for measuring anterior tibial translation
J-Y Jenny1, B Puliero2, G Schockmel3
1Centre de chirurgie orthopédique et de la main (CCOM), hôpitaux universitaires de Strasbourg, 10, avenue Baumann, 67400 Illkirch, France; Université de Strasbourg, 4, rue Blaise-Pascal, 67000 Strasbourg, France.
Introduction:
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.
Hypothesis:
Simultaneous measurement of anterior tibial translation by the GNRB® and the OrthoPilot® in the chosen experimental conditions will result in significant differences between devices.
Material And Methods:
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.
Results:
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.
Discussion:
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.
Level Of Evidence:
II controlled laboratory study.
