ELSEVIER Clinical Biomechanics Vol. 12, No. 3, pp. 18.5-189, 1997 Copyright 0 1997Published by Elsevier Science Limited. ,411 rights reserved Printed in Great Britain 0268~003Y97 $17.00 + 0.00 PII: SO268-0033(97)00076-9 A non-invasive protocol for the determinat‘ion of lumbosacral vertebral angle Y-L Chen’, Y-H Lee* ‘Department of Industrial Engineering and Management, Mingchi institute of Technology; *Department of Industrial Management, National Taiwan Institute of Technology, Taiwan, ROC Abstract Objective. The purpose of this study was to develop a non-invasive method to predict the lumbosacral and vertebral angles. Design. The candidate predicting variables were the externally measured marker angle, pelvic angle, and lumbosacral angle. Background. Several investigators used surface rigid markers to represent the angles of lumbosacral vertebrae. Previous studies show a high level of validity for measuring the lumbar curvature during stance and for obtaining the vertebral angle in the lumbar region. However, our review of literature failed to find a data transformation model illustrating the lumbosacral vertebral angle using external measurements as predictors. Methods. Sixteen healthy male subjects participated in the radiographic and videographic measurements. Data of 12 of the 16 subjects were used for model development, and data of the other four subjects were used for model validation. Results. The results showed significant differences between the directly measured vertebral angle from the X-ray film and the externally measured angles of the surface markers at the L5 and S, levels (P<O.O5). Linear regression models for calculating vertebral angles were developed with I? values of 0.97,0.98,0.91, and 0.92 for the vertebral levels of L,, Ls, Lg, and S, respectively. The validation result showed that there was no significant difference between the calculated and the X-ray data. Conclusions, The protocol of using the skin-surface rigid markers and the predicting models was justified in the study to provide a simple and valid non-invasive method for the recording of the internal vertebral angle in the sagittal plane. Relevance Measurements of lumbosacral vertebral angle are important in assessing the stresses acting on the low back in lifting. The results of this study provided a simple and valid non- invasive method by rigid markers for the prediction of internal vertebral angles under various trunk positions. @ 1997 Published by Elsevier Science Ltd. All rights reserved. Key words: Lumbosacral vertebral angle, radiographic and videographic measurements Clin. Biomech. Vol. 12, No. 3, 165- 189, 1997 Introduction This implied the need for further examinations on the Measurements of lumbosacral vertebral angle are important in assessing the stresses acting on the low back in lifting. Much of the clinical literature suggest that lumbar lordosis and pelvic tilt are related’**; however, poor correlations are found in other studies3,4. assumed relationships of the vertebral angle, pelvic tilt, and lumbosacral angle. Many methods of measuring the lumbar spine and pelvic positions have been investigated3,5-7. Among various techniques, the radiographic method will probably always be the most accurate one; however, non-invasive measurements are also of value for clinical Received: 29 November 1995; Accepted: 6 November 1996 Correspondence and reprint requesf lo: Dr Lee, National Taiwan Institute of Technology, No. 43 Kee-Lung Road, Set 4, Taipei, Taiwan, ROC purposes’. The preference of non-invasive technique over radiographic methods can be due to the merits of less expense, fewer technical difficulties, and smaller risk of radiation exposure.