Fig. 2. Measured parameters using axial computed tomography at the level of the 1st posterior sacral foramen. S1D: 1st posterior sacral foramen depth defined as the length from the posterior surface of the sacrum to the margin of the sacral canal, S1W: 1st posterior sacral foramen width defined as the largest diameter of the S1 posterior foramen, S1A: angle of the 1st posterior sacral foramen defined as the angle between the S1 posterior foramen and the midsagittal line of the sacrum, S1ds: 1st posterior sacral foramen distance defined as the distance between the midsagittal line of the sacrum and the parallel line passing through the center of the S1 posterior foramen.
© Korean J Pain
