RESUMO

OBJECTIVE: Our purpose was to evaluate the validity and reliability of the laxity with the GNRB arthrometer in subjects with anterior cruciate ligament injury. MATERIAL AND METHOD: A diagnostic study was performed by three operators using the Genourob arthrometer, measuring the displacement of the anterior cruciate ligament. The concordance was assessed by the intraclass correlation coefficient mixed effects model, Lin correlation coefficient and graphic method from Bland-Altman. Using the anterior cruciate ligament tear as a dependent variable and the Genourob measurement as an independent variable, a logistic regression was determined. RESULTS: Obtaining the complete information of 157 knees. The measurements with the Genourob arthrometer distributed symmetrically, with mean ± standard deviation of knees with anterior cruciate ligament injury: 5.64 ± 1.72 and knees without anterior cruciate ligament injury: 3.29 ± 1.72. The ICCs as well as the LCCs were equal to or greater than 0.99. The BA showed discrepancy for a pair of observations no greater than 7.64%. The odds ratio of the knee displacement measurement for the presence of anterior cruciate ligament injury was 4.04 (95% CI: 2.59-6.32; p-value < .01) with a ROC area of 0.863 (95% CI: 0.789-0.9456). The cut-off point of the anteroposterior knee displacement located at 6.8 mm determined a sensitivity of 74.4% and specificity of 93.8%, with a Youden Index = 0.67. CONCLUSION: The Genourob arthrometer is reliable and valid to establish where laxity values correlate with total thickness tears of the anterior cruciate ligament.