2017 ISAKOS Biennial Congress ePoster #1098

 

Experimental Validation of the GNRB Device for Measurement of the Anterior Translation of the Knee in Comparison to a Reference Navigation System

Jean-Yves Jenny, Prof., Strasbourg FRANCE
Sebastien Harnoist, MR, Laval FRANCE
Gilles Schockmel, MD, Illkirch FRANCE
Philippe Clavert, MD, PhD, Strasbourg FRANCE
Nicolae Hazaparu, MD, Illkirch FRANCE

University Hospital Strasbourg, Strasbourg, FRANCE

FDA Status Not Applicable

Summary

he use of the GRNB device for routine evaluation of ACL deficient knees or after ACL reconstruction may be recommended.

Abstract

Introduction

Quantitative evaluation of the knee anterior laxity by clinical examination is not precise. Instrumented techniques may have a lower accuracy than expected. The GNRB ® system was developed to improve precision and accuracy of this measurement. Encouraging clinical results have been published, but no experimental study has been performed. The goal of this study was to validate the measurement of anterior knee laxity of gross specimens by the GNRB system by comparison with a navigation system taken as the reference tool. The following hypothesis was tested: the measurement of anterior knee laxity of gross specimens by the GNRB system will differ from that with a navigation system.

Material And Methods

5 pairs of fresh frozen gross specimens were analyzed. The knee was positioned at 20° of flexion on a special splint. An increasing calibrated postero-anterior force was applied; the tibia anterior translation was measured simultaneously by the GNRB ® system and a navigation system for each applied force. Three settings were used for each knee: intact ACL and ALL, section of the ACL or ALL (randomly assigned to each knee of a pair), section of both ACL and ALL. The reference for each knee was the measurement by intact knee. The stiffness of the knee in anterior translation (slope of the curve force vs anterior translation) was calculated. The paired differences between GNRB and navigated measured translations were compared in the whole material (120 measures), for each applied force and for each ligamentous status by a paired Student t-test and calculation of the correlation coefficient. The coherence between both measurements was assessed according to the Bland-Altman technique. All tests were performed at a 0.05 level of significance.

Results

The mean paired difference between GNRB and navigated measurements irrespective from the applied force and the ligamentous status was 0.12 ± 1.8 mm (ns). Only 28 paired differences (23 %) were greater than ± 2 mm. There was a strong correlation between both measurements (R²=0.91) (figure 1). There was a good coherence between both measurements (R²=0.029). Similar results were observed when considering the applied force or the ligamentous status.

Discussion

The hypothesis was rejected. The GRNB and navigated measurements of anterior knee laxity were not different for all situations tested. Neither statistically significant nor clinically relevant difference was identified between GNRB and navigation measurements of the anterior knee laxity, whatever ligamentous status concerning ACL and ALL. Furthermore, there was a strong correlation and a good coherence between these measurements. These results suggest that the GNRB system may be considered as a valid tool for measurement of the anterior knee laxity.

Conclusion

The use of this device for routine evaluation of ACL deficient knees or after ACL reconstruction may be recommended.