Research study. Intramachine and intermachine reliability of the biodex and cybex® II for knee flexion and extension peak torque and angular work

Abstract

The purpose of this study was to assess intramachine and intermachine reliability of the Biodex and Cybex® II. Subjects were 10 healthy volunteers between ages 21 and 40. Both legs of each subject were tested twice on each isokinetic device for concentric knee flexion and extension peak torque and angular work at 60°/sec and 180°/sec. The approximate knee range of motion (ROM) for both machines was 0 to 150° flexion. The intraclass correlation coefficient (ICC) was used to assess reliability for: 1) raw data from each instrument, and 2) windowed data from ranges of motion that were common to all subjects and that excluded Cybex II impact artifact data. Repeated measures ANOVA procedures were used to test for differences among the four testing sessions for the windowed data. Intramachine reliability using raw data was 0.38 to 0.89 for the Cybex II and 0.67 to 0.97 for the Biodex. Intramachine reliability using windowed data was 0.90 to 0.96 for Cybex II and 0.89 to 0.97 for the Biodex. Intermachine reliability was 0.41 to 0.93 using raw data and 0.79 to 0.95 using windowed data. Significant differences were detected between measurements on the two devices for six of the eight dependent variables. The results suggest clinicians can improve reliability of isokinetic measurement on the Biodex and Cybex II by assessing data within the middle segments of ROM on each device and by excluding Cybex II impact artifact data. The results also indicate that measurements on one of the two devices tested in this study may not be generalized to the other device.