60 patients with mechanical low back pain were randomized to a slump sitting method or a conventional method when surgeons were obtaining lumbar flexion radiographs to determine spinal instability. Although patients underwent both methods, randomization indicated which method would be performed first. The study was conducted in order to determine which method was able to more effectively identify angulation and displacement in spinal segments and in turn lead to more precise diagnoses of instability. Using a slump sitting method to obtain radiographs yielded significantly greater flexion angles in all lumbar spinal segments. In turn, an 8.33% increase in spinal stability diagnosis was reported as well. Differences in displacement were comparable between groups, however, a trend favouring the slump sitting method was observed.