CAPACITY OF THE LUMBAR SPINAL CANAL IN THE GREEK ADULT POPULATION

Abstract

The capacity of the lumbar spine canal has direct relation to space-compromising conditions. Primary narrowing of the canal may produce no symptoms, but a slight reduction in capacity as a result of degenerative lesions, age, or disc bulging may result in symptomatic spinal canal stenosis. We studied the dimensions in the adult Greek population in order to find the variability factor in the capacity of the lumbar spinal canal.

The dimensions of the lumbar spinal canal were measured in 27 adult men and 42 adult women, all under the age of 50. MRI was used to measure four levels of the spine (L2 through L5). The AP and transverse diameters, as well as the cross section area, were measured at each level. Mean age (sd) of females was 34.8 (6.8) years. Mean age for males was 35.2 (7.3) and was comparable to women (P0.8). Mean age of a third group of 11 males over the age of 50 was 54.5 (2.6). All individuals included in the study were healthy and without any apparent degenerative changes in the lumbar spine or any symptoms related to it. Hotelling’s tests (Anderson, 1958), in terms of multivariate measurements of the spinal canal, were used to compare both genders and the two age levels. Tests for trends in the lumbar levels L2 through L5 were based on the exact binomial distribution for the number of cases exhibiting a complete trend from L2 to L5. The reported significance levels are adjusted for multiplicity of tests.

The relation of spinal width to lumbar levels is shown separately for the groups of males and females women under the age of 50 and for the group of males under over the age of 50. In all four lumbar levels, the group of men over 50 years old had a narrower spinal canal compared with men under 50 years old (2=0.005). This was particularly evident in levels L2 and L5 where the spinal canal for older men was narrower by factors of 15.5% and 13.1%, respectively. In the two gender groups of comparable age, spinal width was found to differ between men and women (2< 0.0001). In particular, the females had a wider spinal canal than males in levels L2, L3 and L4 and a narrower canal in level L5. Spinal width was found to exhibit a decreasing trend in lumbar levels L2 through L5. The evidence for this trend was strong for all three groups: females under the age of 50 (P< 0.0001), men under 50 (2< 0.005), and the older men (P< 0.0001). A similar trend was present for the anteroposterior diameter, as well as for the Transverse diameter. A numerical summary (mean, sd) of all spinal measurements is reported.

We believe this study to be an important one that provides useful information regarding the capacity of the lumbar spinal canal, thus helping the surgeon to properly evaluate the stenotic patient.