Percutaneous approach to the fifth lumbar and first sacral disc.

Reaching the L5-S1 disc space through a posterolateral percutaneous approach can be challenging and, at times, disappointing when the iliac crest is too high and the angle between the posterior rim of the iliac bone and the lumbar vertebral column is too acute. The authors are introducing a technique through which the two necessary caudal and axial angles of approach are measured and used for precise passage of the initial trocar into the L5-S1 disc space. Specific bony landmarks and their topographic reflection on the lumbar skin are used in finding the caudal angle and calculating the axial angle. The technique has been used in 43 patients with persistently symptomatic L5-S1 disc protrusions, 27 of whom had high iliac rims. Access to the disc space was achieved in a timely manner in 41 patients who subsequently had percutaneous discectomy. The two unsuccessful procedures were because of the blockage of the access tunnel by an extremely swollen nerve root in one patient and a very large transverse process in the other patient. There were no other complications. Because of its accuracy, although the technique can be used routinely for all the posterolateral percutaneous approaches to the L5-S1 disc space, it specifically is useful for patients with high iliac crests.