Test-retest reliability of three-dimensional kinematics using an electromagnetic tracking system during single-leg...

The electromagnetic tracking system (ETS) has been used to analyze three-dimensional (3D) lower limb kinematics. The single-leg squat and stepping maneuver are useful tasks to evaluate lower extremity alignment in a clinical setting. The purpose of this study was to evaluate the test-retest reliability of trunk, pelvis, hip, and knee 3D kinematics using an ETS during single-leg squat and stepping maneuver and compare 3D kinematics between tasks. Twenty healthy volunteers (10 males and 10 females) completed two test sessions 3-5 days apart. Three-dimensional kinematics using an ETS was assessed during single-leg squat and stepping maneuver. Overall, intrarater-intrasession reliability (ICCs=0.83-1.00) and intersession reliabilities (ICCs=0.82-0.97) were high during single-leg squat and stepping maneuver. The intrasession minimal detectable change (MDC) ranged from 1.3° for the knee frontal plane range of motion for single-leg squat to 6.2° for the pelvic transverse range of motion for the stepping maneuver. Intersession MDC values ranged from 1.2° for the ipsilateral trunk lean for the single-leg squat to 8.3° for hip flexion for the stepping maneuver. Healthy participants exhibited greater anterior pelvic tilt, more hip flexion, and less contralateral pelvis forward excursion (p<0.05) during single-leg squat compared with the stepping maneuver. These findings suggest that the 3D kinematics of the trunk, pelvis, hip, and knee using an ETS is reliable during single-leg squat and the stepping maneuver. Minimal detectable change values were low during the evaluated activities. Intertask comparisons revealed differences in hip and pelvis kinematics.