- STUDY DESIGN: Single group repeated measures with multiple raters. OBJECTIVES: To determine the inter-rater reliability of KT-1000 measurements of novice and experienced raters and to provide error estimates for these raters. BACKGROUND: The KT-1000 arthrometer is often used clinically to quantify anterior tibial displacement. Few data have been documented, however, about the relative reliability of KT-1000 measurements obtained by novice compared with experienced users. METHODS AND MEASURES: Two novice and two experienced KT-1000 users performed measurements on 29 knees of 25 patients after anterior cruciate ligament (ACL) reconstruction or with a diagnosis of ACL deficiency. Measurements were performed at 131 N. Interrater and intertrial reliability coefficients (interclass correlation coefficient; ICC) and the standard error of measurement were calculated for expert and novice raters. RESULTS: The interrater ICC for novices was 0.65 and the interrate error was +/- 3.52 mm (90% confidence interval [CI]). The interrater ICC for experts was 0.79 and the interrater error was +/- 2.94 mm (90% CI). CONCLUSIONS: These results suggest that experience in using the KT-1000 is related to the interrater error of measurements and that training is an important consideration when using the KT-1000 arthrometer.