Reliability of a navigation system for intra-operative evaluation of antero-posterior knee joint laxity

Background: The purpose of this study was to investigate about the reliability of measuring antero-posterior laxity within-subjects for in-vivo studies using a navigation system.Methods: The analysis was performed by enroling 60 patients undergoing anterior cruciate ligament ACL reconstruction, and assessing AP laxity during the Lachman and drawer tests.Results: For the navigation system standard deviation for intra-trial measures was 0.7 mm, thus the intra-trial repeatability coefficient was 2.2 mm; standard deviation for intra-trial measure was 1.2 mm, while the reference inter-trial repeatability coefficient between expert surgeons was 3.4 mm.Conclusions: In conclusion, this study suggests that KIN-Nav may represent a new method to measure and document AP laxity intra-operatively with improved accuracy and test the effect of surgical treatment in-vivo with higher sensitivity than in the past and this study quantify its reliability for within-subjects studies performed by a single expert surgeon.