Morphometry of the lumbar vertebrae. An anatomic study in two caucasoid ethnic groups.

A morphometric study of the lumbar vertebrae of 121 skeletons, 63 Italian and 58 Indian, revealed that the mean dimensions of the spinal canal, the lateral recesses, and the vertebral body were significantly greater in the Italian than in the Indian skeletons. The lowest normal limits of the midsagittal diameters of the spinal canal were 12.6 mm in the Italian skeletons and 11.5 mm in the Indian series. The midsagittal diameters of the canal measured, at one or more levels, 10.1-10.8 mm in 5% of the Italian skeletons and 9.0-10.5 mm in 10% of the Indian skeletons. In most vertebrae with midsagittal dimensions of the canal less than 11.5 mm, the width of the recesses was at or below the lower limits of normal. These observations cast doubt on the current view that a midsagittal diameter of the vertebral canal of less than 12.0 mm is pathologic and suggest that the diagnosis of developmental stenosis can not be based only on the dimensions of the spinal canal. Lateral recess stenosis may occur in a normally sized spinal canal but is more likely to occur in developmentally narrow canals.