It is considered that the degenerative changes of the facet joints cause the lumbar canal stenosis of degenerative type. CT of the facet joints shows the relation of the degenerative changes of the facet joints to the lumbar canal. Considerable measurements of the facet joints by CT were made on fifteen cases of lumbar canal stenosis (LCS) and forty-five cases of degenerative spondylosis (OA). There were significant differences between LCS and OA in facet angle, sectional area of the dural sac and A-P diameter of the lateral recess. Especially sagittal orientation and tropism of the facet joints were reffered to the LCS. We suggested that the sagittal orientation of the facet joints accelerated the degenerative changes of them.
