Validity and reliability of skin markers for measurement of intersegmental mobility at L2-3 and L3-4 during lateral bending in healthy individuals: a fluoroscopy study.

It is clinically important to assess kinematic parameters of lumbar spine movement to increase our understanding of lumbar mobility impairments in patients with low back pain. This is the first step for restoration of motor function. The use of non-invasive surface markers has currently attracted the interests of many researchers but scientific utilization of this technique for clinical research requires validity and reliability studies. The aim of the present study was to examine whether skin markers can be used to measure lumbar motions during lateral bending. Twelve healthy individuals were lying in prone position on the video fluoroscopy table and skin markers were attached over their spinous processes. Fluoroscopy images were taken in two positions of neutral and right lateral bending (RLB). The correlation of the L2-3 and L3-4 angles and lumbar curvature between markers and vertebrae measurements in the neutral and RLB positions was determined by Pearson Correlation Coefficient. The Intraclass correlation coefficient (ICC) was used to measure inter-examiner reliability of measurement in five participants. The results showed high reliability (ranging from 0.94 to 0.99) for angular measurements at L2-3 and L3-4 and lumbar curvature and also significant correlation between angular measurement derived from markers and vertebrae at L2-3 (r = 0.7, p = 0.015), L3-4 and lumbar curvature (r = 0.91 p = 0.001). The results showed that motions of skin markers follow the motions of the assigned underlying lumbar vertebrae. Therefore, skin markers can be confidently used for estimation of lumbar movements during lateral bending.