Ultrasound lumbar canal measurement in hospital employees with back pain.

The oblique parasagittal diameter of the lumbar spinal canal at the L5-S1 level was measured in 49 employees of the Wm Jennings Bryan Dorn Veterans' Hospital using real time ultrasound in a case-control study. Individuals with a canal diameter of less than 14 mm represented the lowest 10th percentile in this population and being in the narrowest 10th percentile constituted a risk factor for time missed from work because of low back pain (odds ratio 10.7). Whereas numbers in this pilot study are small, results are consistent with earlier ultrasound studies done in the United Kingdom and with other research showing increased morbidity from low back pain in individuals with small lumbar canals. Ultrasound has advantages over other modalities for measuring the size of the lumbar canal and may be useful as a preplacement screening examination in industry.