Intra- And inter-rater reliability of in vivo three-dimensional measurement of the scapular poses using a marker-based locator

The accurate measurement of three-dimensional scapular kinematics is essential for a better understanding of the mechanical interactions between the scapular and the other segments of the shoulder complex. The purposes of the study were (1) to develop a marker-based scapular locator for measuring scapular poses and (2) to determine the intra-rater and inter-rater reliability of the locator in terms of intra-class correlation (ICC). About 22 healthy volunteers without shoulder pathologies participated in the current study. Each subject was tested separately by two examiners using the marker-based scapular locator while performing static shoulder flexion at 20°, 40°, 60°, 80°, 100° and 120° in the sagittal plane. The reliability models, ICC(2;k) and ICC(3;k), were used to analyze the intra-rater and inter-rater reliability for scapular rotation and translation. Good to excellent intra-user reliability for both examiners was found for the scapular rotations (range: 0.81-0.97) and displacements (range: 0.88-0.99) for different shoulder flexion conditions. Excellent inter-rater reliability was found for scapular rotations (range: 0.92-0.99) and translations (range: 0.92-0.99) for all conditions. The results showed the high intra-And inter-examiner reliabilities for scapular rotations and translation using the marker-based scapular locator. The developed locator will be helpful for future clinical research of the shoulder complex. ? 2018 World Scientific Publishing Co. Pte Ltd. All rights reserved.