In Vivo 3-Dimensional Morphometric Analysis of the Lumbar Foramen in Healthy Subjects

Study Design. In vivo 3-dimensional (3D) morphometric analysis of the lumbar foramen by using 3D computed tomographic models in normal subjects. Objective. To describe foraminal geometry in an asymptomatic cohort measured in 3D. Summary of Background Data. Appropriate assessment of the complex 3D lumbar foraminal geometry is key to correct radiculopathy diagnosis and treatment planning. To the best of our knowledge, there is no other study that quantifies the normal lumbar foramen 3D geometry considering sex, age groups, and spinal levels in vivo. Methods. Subject-based 3D computed tomographic lumbar models were created in 59 asymptomatic volunteers and foraminal height and width were measured on the basis of the model by custom software. The foraminal height and width were compared by sex, age, and lumbar level. Results. Overall, the foraminal height decreased with age. However, although the foraminal height in males decreased with age at all spinal levels, the foraminal heights in females did not. The foraminal height was significantly larger in the upper lumbar levels in both sexes. The foraminal width in males was significantly smaller than in females for all age groups. The foraminal width in both sexes also decreased similarly with age. The foraminal widths at the lower lumbar levels were significantly smaller than those at the upper levels. Age-related foraminal width decreases were seen in all lumbar levels as well. Conclusion. This study described foraminal geometry in vivo in an asymptomatic cohort measured in 3D. Age-related foraminal height decrease was noticeable in males and in the lower lumbar levels. Age-related foraminal width decrease was shown in both sexes and in all lumbar levels. Such information can be used as baseline data for diagnosis of foraminal stenosis and treatment modality planning.