Radiographic measurement of lumbar spinal canal size and canal/body ratio in normal adult Saudis

BACKGROUND: Defining normal values of lumbar spinal canal among adult Saudis is essential for reliable evaluation of patients with low back pain or with signs and symptoms of lumbar canal stenosis. OBJECTIVE: To determine the normal dimension of the lumbar spinal canal in adult Saudis, and to determine whether there is any racial difference in the morphometry of the lumbar spinal canal. MATERIALS AND METHODS: A computed tomography measurement of the main dimensions of the lower three lumbar vertebral canal were made in 170 normal Saudi adults at King Fahad University Hospital, AI-Khobar, Saudi Arabia. For the sake of consistency, all measurements were taken by one observer and the results were recorded as the mean of 2 measurements per each dimensions. To evaluate the significance obtained, Student t test were carried out. RESULTS: The results of measurement of the mid-sagittal diameter of the vertebral canal showed that the mean male mid-sagittal diameters were slightly wider than those of the female but the differences were not statistically significant. The ratio is increased steadily as we go from L3 to L5 especially in the females. The mid-sagittal canal/body ratio is higher in the female in this population, which indicates that the lumbar canal is more capacious in females than that of the males. The transverse canal/body ratio was calculated to be from 0.56 to 0.57 in the males, and from 0.61 to 0.63 in the females. Although the transverse diameters of the vertebral body increased steadily from L3 to L5, the canal/body ratio in the transverse plane showed a relatively constant relationship. In age group over 60 years, the mid-sagittal diameters were smaller than those of younger generations at all levels. The interpedicular diameter was greatest in the 30 to 39 years old age group at all levels. CONCLUSIONS: The mid-sagittal and transverse diameter of the lumbar spinal canal among adult Saudis is similar to the measurement in the white population; the radiologic criteria of spinal canal stenosis should be identical between these 2 populations.