Reproducibility of Rasterstereography for Kyphotic and Lordotic Angles, Trunk Length, and Trunk Inclination A Reliability Study

Study Design. Determination of reliability with 3 investigators using a collective of healthy volunteers. Objective. To determine the reliability of rasterstereography 3-dimensional back surface analysis and reconstruction of the spine in healthy test subjects. Summary of Background Data. Rasterstereography has been in clinical use since 1989 for patients with scoliosis and other spinal deformities and it significantly reduces the need for otherwise indispensable radiographs. The validity of this device has previously been examined in other studies. This study was performed to evaluate the reliability of rasterstereography for clinical application in diagnostic and follow-up examinations. Methods. Fifty-one healthy volunteers were examined rasterstereographically by 3 investigators. Each investigator made a series of 3 measurements of each participant in which 8 spine parameters including kyphotic angle ICT-ITL (max.), kyphotic angle VP-ITL, kyphotic angle VP-T12, lordotic angle ITL-ILS (max.), lordotic angle ITL-DM, lordotic angle T12-DM, trunk length VP-DM and trunk inclination were measured. Cronbach alpha was calculated. The influence of high or low body mass index on the accuracy of the technique was evaluated as well. Results. Cronbach alpha for the intratester-reliability of the kyphotic angle ICT-ITL (max.) for the 3 investigators has values between 0.921 and 0.992. The intertester-reliability for the same parameter is 0.979 (95% CI). In this study group a meaningful association between body mass index and reliability of the device was not found. Conclusion. The reliability revealed very good results, both for intratester and for intertester reliability. The technique is well suited for analysis of the back in standing position. The body mass index has no influence on the reproducibility.