Radiographic measurements of lumbar spinal canal size and their relation to back mobility.

A total of 197 men and women with history of previous back pain were radiographed and clinically examined. Measurements related to the shape and size of the spinal canal were subsequently made from the lumbar radiographs. Interarticular distance and the ratio between interarticular and interpedicular distances were significantly less in women with restriction of lumbar extension, sidebending, and rotation: not in men. Anteroposterior (AP) foraminal distances and pedicular lengths were less in men with restricted extension and sidebending, although not in women. Midsagittal diameters were not significantly less in those with restricted mobility. The radiographic differences between men and women with restricted back mobility arise partly from the sexual differences in interarticular and AP foraminal distance, the former being less in women, the latter in men. This suggests a different pathogenetic factor in the two sexes.