Slump Sitting X-ray of the Lumbar Spine Is Better Than Conventional Flexion

Power calculation was performed based on preliminary pilot results using a clinically set difference of 10 degrees (SD 15 degrees) change in mean global lumbar spine flexion between sitting and standing postures. An estimated sample population of 100 patients was deemed necessary for this study to fulfill a statistical power of 90% and a two-sided 5% significance level.

Block randomization of every 4 subjects was performed at the beginning of the study to ensure equal numbers of subjects in both study arms for comparison and these results were concealed in envelopes.

During the clinical consult, history taking was performed as per a usual clinic visit. Specific patient's details including age, occupation, presence and severity of back pain, presence and severity of leg pain, and neurological symptoms were documented. Physical examination was performed accordingly and parameters such as clinical range of motion of the lumbar spine, neurological signs and provocative tests were recorded for later analysis.

For the flexion radiographs, both the new and conventional methods were performed on each patient. These pictures were made into charts and visually displayed. They serve as instructional manuals for patients during the radioimaging process, which are again reinforced with verbal instructions from the on-duty radiographers.

Both images were done with the X-ray beam projected from the patients's left and at a distance of 100cm from the patient. The central beam was directed at the estimated centre of L3, with T11 vertebral body and mid-body of the sacrum serving as superior and inferior limits respectively. A single extension view of the lumbar spine was also performed after these flexion views. All radiographs were stored on Digital Imaging and Communications in Medicine (DICOM) format and viewed with Centricity Enterprise Web V3.0 (8.0.1400.128) for assessment.