Reproducibility of the Flexicurve for Assessment of Thoracic and Lumbar Spine Range of Motion

The purpose of this study was to evaluate the intra- and inter-rater reproducibility of the Flexicurve for assessing the flexion and extension range of motion of the thoracic and lumbar spine.

Intrarater reproducibility (n = 35) was assessed by a single rater on 2 different days, and inter-rater reproducibility (n = 37) was assessed on 1 day by 3 different raters. The assessment protocol involved palpation and identification of spinous processes (SP), molding of the Flexicurve along the maximum range of flexion and extension, marking of SP on the Flexicurve, careful removal of the Flexicurve, drawing of the curvature contours obtained by the Flexicurve on paper, identification of SP on the drawing, photographic recording of the drawn contour, and analysis of the photograph using MATLAB 8.5. Data were analyzed using intraclass correlation coefficient (ICC), standard error of measurement (SEM), and minimum detectable change (α < 0.05).

Excellent ICCs were obtained for intrarater reproducibility of thoracic and lumbar spine flexion and extension, with SEM ranging from 0.7° to 1.7°. Except for lumbar spine extension, which achieved satisfactory ICC, inter-rater reproducibility showed excellent ICCs for other measures, with SEM ranging from 2° to 5°. Intrarater reproducibility of the software resulted in excellent ICCs, with SEM ranging from 0.7° to 4.4°.

Due to established reproducibility and precision, the Flexicurve can be used for assessments of thoracic and lumbar spinal range of motion. Rigorous methodological care is recommended for its protocol, especially regarding thoracic extension.