Anatomic variations and pathologic conditions as risk factors of complications in percutaneous lumbar nucleotomy

This study was carried out to assess anatomic variations and pathologic changes associated with a potentially increased risk of complications during percutaneous nucleotomy. The MRI and CT examinations of 88 patients were reviewed with regard to the positional relationship between the trajectory to the disc and the bowel and iliac vessels respectively at the L4-L5 and L5-S1 levels. Pathologic conditions involving the anterior part of the annulus were assessed both by MRI and by CT-discography of 97 discs. The shortest distance from the needle course to the bowels was 29 mm. At ten other disc levels this distance was less than 40 mm. The position of the bowels is influenced by the size of the patient, the size and course of the psoas muscles and the amount of retroperitoneal fat. The bowels are at greaten distance from the trajectory at the L5-S1 than at the L4-L5 level. The risk of bowel puncture seems to be minimal. The iliac vessels were positioned behind the midportion of the disc in three patients. There was greater variation and a shorter distance to the trajectory at the L5-S1 than at the L4-L5 level. Anterior disc hernias, and particularly severe annular degeneration involving the anterior part of the annulus are frequently seen. These conditions include a weakening of the annulus and may increase the risk of anterior perforation during nucleotomy.