Evaluation of the reproducibility of the KT-1000 arthrometer

The aim of the study was to examine whether the KT-1000 arthrometer was reliable when it came to distinguishing between a group of patients with a chronic anterior cruciate ligament (ACL) rupture and a group of patients without an ACL rupture, and to examine the reproducibility of the examination between two experienced examiners. The aim was also to examine whether the KT-1000 measurements were dependent on whether the patients were awake or under anaesthesia. The study comprised 40 patients: Group A consisted of 20 patients who had a chronic unilateral ACL rupture and Group B consisted of 20 patients who were scheduled for arthroscopy due to knee problems other than an ACL rupture. The KT-1000 examination was performed before surgery by two experienced physiotherapists (PT I and PT II). PT II subsequently performed a retest of the patients under anaesthesia. The mean anterior side-to-side laxity difference between PT I and PT II was 0.2 mm in Group A and 1.8 mm in Group B (n.s., P=0.03). The anterior side-to-side measurements of knee laxity revealed significant differences between Group A and Group B, independent of who the measurements were made by when the patients were awake (PT I P=0.011, PT II P=0.001). However, no significant difference (P=0.063) was found when the patients were under anaesthesia. The interclass correlation coefficient (ICC) between PT I and PT II in Group A was 0.55 (P=0.005) for the anterior side-to-side laxity, while it was 0.60 (P=0.002) in Group B. There were no significant differences within Group A or Group B between the measurements made when people were awake compared with those under anaesthesia. The conclusions of the study were that the KT-1000 arthrometer was able to distinguish a group of patients with an ACL rupture from a group without one. The reproducibility of the KT-1000 measurements of anterior knee laxity between two experienced examiners was considered as fair. Furthermore, the measurements were not dependent on whether the patients were awake or under anaesthesia.