Concurrent validity of DorsaVi wireless motion sensor system Version 6 and the Vicon motion analysis system during lifting

Abstract

Background Wearable sensor technology may allow accurate monitoring of spine movement outside a clinical setting. The concurrent validity of wearable sensors during multiplane tasks, such as lifting, is unknown. This study assessed DorsaVi Version 6 sensors for their concurrent validity with the Vicon motion analysis system for measuring lumbar flexion during lifting. Methods Twelve participants (nine with, and three without back pain) wore sensors on T12 and S2 spinal levels with Vicon surface markers attached to those sensors. Participants performed 5 symmetrical (lifting from front) and 20 asymmetrical lifts (alternate lifting from left and right). The global-T12-angle, global-S2-angle and the angle between these two sensors (relative-lumbar-angle) were output in the sagittal plane. Agreement between systems was determined through-range and at peak flexion, using multilevel mixed-effects regression models to calculate root mean square errors and standard deviation. Mean differences and limits of agreement for peak flexion were calculated using the Bland Altman method. Results For through-range measures of symmetrical lifts, root mean squared errors (standard deviation) were 0.86° (0.78) at global-T12-angle, 0.90° (0.84) at global-S2-angle and 1.34° (1.25) at relative-lumbar-angle. For through-range measures of asymmetrical lifts, root mean squared errors (standard deviation) were 1.84° (1.58) at global-T12-angle, 1.90° (1.65) at global-S2-angle and 1.70° (1.54) at relative-lumbar-angle. The mean difference (95% limit of agreement) for peak flexion of symmetrical lifts, was − 0.90° (-6.80 to 5.00) for global-T12-angle, 0.60° (-2.16 to 3.36) for global-S2-angle and − 1.20° (-8.06 to 5.67) for relative-lumbar-angle. The mean difference (95% limit of agreement) for peak flexion of asymmetrical lifts was − 1.59° (-8.66 to 5.48) for global-T12-angle, -0.60° (-7.00 to 5.79) for global-S2-angle and − 0.84° (-8.55 to 6.88) for relative-lumbar-angle. Conclusion The root means squared errors were slightly better for symmetrical lifts than they were for asymmetrical lifts. Mean differences and 95% limits of agreement showed variability across lift types. However, the root mean squared errors for all lifts were better than previous research and below clinically acceptable thresholds. This research supports the use of lumbar flexion measurements from these inertial measurement units in populations with low back pain, where multi-plane lifting movements are assessed.

Assessing the Impact of Sensor Orientation on Accelerometer-Derived Angles: A Systematic Analysis and Proposed Error Reduction

“…Previously studies calculating peak ROM angles, in comparison to a gold standard, have reported limits of agreement ranging from -8.06 • to 5.67 • [25] and −3.86 • to 4.69 • [11]. Data from the current study showed similar but tighter limits of agreement (−1.65 • to 4.38 • ) prior to correction, and therefore it is possible that some of the range of these errors is due to sensor orientation, especially as no mention of orientation correction was made in these works.…”

“…Despite this common use of accelerometers, it is not clear if initial sensor orientation angle has been considered in the quantification of the angles or ROM reported. For example, previously reported limits of agreement between gold standard methods and accelerometers, without correcting for initial orientation, range from -8.06 • to 5.67 • [25] and −3.86 • to 4.69 • [11], meaning that 95% of future paired observations are likely to fall between this range of error. These error ranges are large, and it is questionable as to whether this is a true reflection of the sensors' capabilities or a function of the initial sensor orientation as a source of error.…”

Estimating Compressive and Shear Forces at L5-S1: Exploring the Effects of Load Weight, Asymmetry, and Height Using Optical and Inertial Motion Capture Systems

“…Kinematic data obtained from IMC systems have been validated in several studies in laboratories against data obtained from OMC systems [ 19 , 20 , 21 , 22 , 23 , 24 ]. Estimating kinetic variables such as backloading from IMC systems has also been validated in laboratories by using force platforms or instrumented shoes to measure the ground reaction forces [ 20 , 25 , 26 , 27 , 28 ].…”