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 det ermine sacral inclination is by radiograph, but methods to measure sacral i nclination externally with an inclinometer have also been introduced. Objective: To determine the validity of the inclinometer in measuring the s acral inclination in patients with LBP. Subjects: Adult patients with LBP who were referred by the a general practi tioner 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 w as used to define the measurement error. Results: Of 50 consecutive patients with LBP, radiographs of 41 patients we re useful for the required measurements on the radiograph. The mean differe nce between the radiographic and inclinometer method was 23.12 degrees. The measurement error was 8.26 degrees. Regression analyses showed poor correl ation between both methods (r = 0.28). Conclusions: The method we used to measure sacral inclination with an incli nometer proved to be invalid.