Measurements of the lumbar spinal canal of Chinese by computed tomography

The study of the lumbar canal sizes in Chinese has not been reported before. Thirty adult patients, aged 20 to 40 years, who sustained thoracolumbar or lumbar fracture-dislocation and needed further computed tomographic (CT) scanning were included in this study. There was no significant back pain or sciatica on these patients before. Measurements of the med-sagittal anteroposterior (A-P) and interpedicular (I-P) diameters of the spinal canals L1 to L5 were requested at the same time during CT scanning. The results show that the lowest normal limits of the A-P and I-P diameters of the lumbar canals in Chinese are 11 mm and 19 mm respectively. The I-P diameters increase progressively from the first to the fifth vertebrae. The A-P diameters, however, are more variable and shortest at L2, L3 and L4 vertebrae.