Abstract
Reliability of measurement of maximum isokinetic muscle performance in subjects with rheumatoid arthritis has not been reported for the KinCom dynamometer. The aim in this study was to estimate intra and inter-session reliability in knee extensor and flexor muscles. Concentric peak torque (Nm) of knee extension and flexion at 60o.s-1 and 120o.s-1 was measured in 18 subjects(49.7 +/- 5.3 (29-76) years) with rheumatoid arthritis using a standardised protocol. Intra-session reliability (ICC 3,1) assessed in six subjects was found to be high in extensor (0.99) and flexor muscles (0.99). Comparison between left and right knees showed no statistically significant differences. Inter-session reliability (ICC 2,3) assessed over a six-week interval was also high for extensors (60o.s-1 = 0.97, 120o.s-1 = 0.97) and flexors (60o.s-1= 0.94, 120o.s-1= 0.97). These findings indicate that when using a single rater, inter and intra-session reliability of knee muscle peak isokinetic concentric torque measurement are acceptable. The time interval between test sessions of six weeks reflects the clinical environment. Therefore this protocol provides a useful test for evaluation of therapeutic interventions directed at the knee.