Measuring the sacral inclination angle in clinical practice: Is there an alternative to radiographs?

Background: In patients with low back pain (LBP) the position of the pelvis is often a focus of physical or manual therapy. The “gold standard” to determine sacral inclination is by radiograph, but methods to measure sacral inclination externally with an inclinometer have also been introduced. Objective: To determine the validity of the inclinometer in measuring the sacral inclination in patients with LBP. Subjects: Adult patients with LBP who were referred by the general practitioner to the hospital for radiograph examination of the lumbosacral spine were included. Methods: Measurement of sacral inclination acquired with the inclinometer, simultaneous with the x-ray exposure, was compared with the “gold standard” measurement of sacral inclination on the radiograph. Regression analysis was used to define the measurement error. Results: Of 50 consecutive patients with LBP, radiographs of 41 patients were useful for the required measurements on the radiograph. The mean difference between the radiographic and inclinometer method was 23.12°. The measurement error was 8.26°. Regression analyses showed poor correlation between both methods (r = 0.28). Conclusions: The method we used to measure sacral inclination with an inclinometer proved to be invalid. (J Manipulative Physiol Ther 2001;24:505-8)