Quantitative analysis of the measuring capabilities of the KT-1000 knee ligament arthrometer

Abstract

The KT-1000 arthrometer was evaluated in vitro and in vivo to determine accuracy and quantify effects of potential error sources in clinical application. The KT-1000 arthrometer in vitro accuracy was evaluated by making 30 measurements of 13 known displacements (range, +15 to -15 mm). The effect of applied force on malalignment measurements was evaluated in vitro by making repeated measurements with force applied 5 degrees, 10 degrees, and 15 degrees from the vertical position. The effect of malpositioning the device along the joint line was evaluated in vivo by making repeated measurements 1 cm proximal and 1 cm distal to the joint line. The KT-1000 arthrometer was accurate in vitro (average error, 0.13 mm; SD, 0.12 mm). The range of measurements increased when the angle of force application was increased. Positioning the device 1 cm proximal to the joint line produced larger anterior translation measurements in vivo than those at the joint line (5.8 versus 5.4 mm), while positioning it 1 cm distal produced smaller measurements (4.4 mm). The KT-1000 arthrometer's accuracy indicates great potential for clinical application, but one must ensure that the displacing force is directed properly and the device is positioned accurately over the joint line.

Instrumented measurements of knee laxity: KT-1000 versus navigation

“…In fact, significant variation in measurements can occur when the anterior directed force is applied off-center and when the device is not aligned with the joint line [20]. Therefore the KT-1000 arthrometer has a great potential for clinic use, but sources of mistakes in measurement must be minimised.…”

Frequency content asymmetry of the isokinetic curve between ACL deficient and healthy knee

“…Toque values were collected at 1 ms intervals (100 Hz). Maximal static anterior tibial translation was assessed by the KT-1000 arthrometer (Medmetric Corp., San Diego, CA) according to Kowalk et al (1993). The use of KT-1000 is a standard procedure in the assessment of the anterior laxity in ACL deficient knees (Daniel et al, 1985;Steiner et al, 1990).…”

Anterior cruciate ligament assessment using arthrometry and stress imaging

“…The few other published reliability measures vary, with intra-rater reliability ranging from 0.67 to 0.99 and inter-rater reliability ranging from 0.65 to 0.92 [37,40,44]. Many factors influence test reliability, including examiner experience, device overtightening, improper positioning, inconsistent force application, leg external/internal rotation, examiner hand dominance, and knee effusions [34,39,40,[44][45][46][47][48][49]. Although only explicitly studied with the KT system, several of these factors could conceivably affect other devices as well.…”