[Extent of fenestration in one-level operations for lateral herniation of the intervertebral disk of the lumbar segment of the spine].

In the years 1969-1986 operations were carried out in 1650 cases of lateral prolapse of the lumbar nucleus pulposus at one level, they accounted for 75% of patients operated on for symptomatic sciatic pains. The operations were done in lateral recumbent position. In 29% of cases it was necessary to extend the typical fenestration by reducing the size of one or two halves of the vertebral arches, and in 12% of cases full hemilaminectomy was done. The most frequent cause of fenestration extension was narrow yellow ligament and massive broad vertebral arches at the level of the prolapsed nucleus, as well as congenital or acquired narrowing of the lateral recess of the vertebral canal. In only 4% of cases the necessity of fenestration extension was due to displacement of the free fragments of the prolapsed nucleus far from the intervertebral space or their falling into the meningeal sac.