Transdiscal L5-S1 screws without transpedicular L5 screws in the treatment of adult L5-S1 spondylolisthesis – report on two cases and review of the literature

There are several well-established techniques for the operative treatment of symptomatic L5-S1 spondylolisthesis. Standard surgical approaches typically include an interbody cage for posterior, transforaminal, or anterior interbody fusion, L5 pedicle screws, and sacral fixation. In adult high-grade spondylolisthesis, the L5-S1 intervertebral disc is often severely narrowed or completely degenerated, with only residual fibrous components attached to the vertebral bodies. Such cases are usually treated by in-situ fixation. Attempting to sufficiently distract the discal surfaces for interbody device implantation presents a significant technical challenge, and the resulting distraction and reduction may potentially injure the L5 nerve roots passing through the anteriorly displaced neuroforamina. The direct pediculo-body fusion technique has been somewhat forgotten due to the emergence of more complicated and expensive instrumentation options that promise better fusion rates and fewer complications. We present two cases where a modification of the original Grob technique was applied and discuss the rationale for patient selection. Both patients achieved complete symptom resolution. No surgical complications were observed. Evidence of bony interbody fusion was confirmed at the 3-month follow-up.