Objective: Accurate measurement of thoracic kyphosis has high value in the evaluation of patients with spinal kyphosis and in assessing the effectiveness of different treatment methods. Recently, Dual Digital Inclinometer (DDI) has introduced as a non-invasive tool that can measure the kyphosis angle. According to available information there is only one published study regarding the validity and reliability of this instrument in our country. Therefore, this study aimed to evaluate the Validity and reproducibility of DDI in measuring thoracic kyphosis in women over 45 years.

Materials & Methods: In this methodological study, thorasic kyphosis was measured by DDI device three times on 20 women aged 45-70 years. The first two measurements were taken with an hour apart in same day to assess the within- day and the third measurement was taken one day later to assess the between-days reproducibility. Finally, the validity of obtained values of thorasic khyphosis by DDI compared with Cobb angle which measured by the same examiner on radiological films. ICC correlation coefficient test with 95% confidence intervals was used for data analysis.

Results: The validity of values obtained by DDI compared to the Cobb angle, as a gold standard, was high (ICC=0.86). Within-day and between-days thorasic kyphosis measurements using DDI were shown to be reproducible with high ICC values. (0.95 for within-day and 0.93 for between days respectively).

Conclusion: According to the present study, the DDI is a valid and reproducible tool for non-invasive measurement of thoracic kyphosis in women over 45 years.