Study Design. Repeatability and reliability for measuring methods for real-time lumbar range of motion. Objective. We established a novel set of marker positions for 3-dimensional motion analysis (VICON system) to determine lumbar spine range of motion (LROM) and lumbar motion precisely; we compared the repeatability and reliability of VICON system with those of an electrogoniometer. Summary of Background Data. The assessment of the LROM using x-ray is still one of the most precise methods, despite the radiation exposure. To avoid this, alternative methods, such as the VICON system and electrogoniometer, have been widely used. No study has reported the repeatability and reliability of LROM measurements using a VICON system and electrogoniometer. Methods. The VICON system and electrogoniometer measured LROM and lumbar motion in 7 healthy males during 7 days. Differences between both systems were analyzed using Bland- Altman plots. Repeatability and reliability of the LROM measurements was assessed using coefficients of multiple correlations and intraclass correlation coefficients, respectively. Standard error of measurement was calculated to quantify the systematic error in LROM measurements. Results. The mean maximum LROM values using the VICON system/ electrogoniometer were 42 ° /52 ° for flexion, 17 ° /24 ° for extension, 16 ° /16 ° for lateral bending, and 8 ° /2 ° for axial rotation, respectively. Between VICON system and the electrogoniometer, Bland-Altman plots revealed no discrepancies in LROM values except for flexion. Coefficients of multiple correlations for LROM showed excellent repeatability. LROM measurements with VICON system showed excellent reliability for flexion and extension and fair-to-good reliability for other motions. LROM measurements with the electrogoniometer showed excellent reliability for flexion and fair-to-good reliability for other motions. Except for axial rotation, maximum intraclass correlation coefficients using VICON system were more reliable than the electrogoniometer for measuring lumbar motion. Conclusion. VICON system with our novel marker set allows practical and reliable longitudinal assessment of dynamic LROM.
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