Posterior L5-S1 transdiscal screws for high grade spondylolisthesis - a systematic review

OBJECTIVE: The surgical management of high-grade lumbar spondylolisthesis (HGLS) is complex and aims to achieve both a solid fusion that is able to support the high shear forces of the lumbosacral junction, as well as neural decompression. We performed a systematic literature review of the safety and efficacy of posterior transdiscal (PTD) screw fixation from L5S1 for HGLS and its variations. METHODS: A systematic literature review following the PRISMA guidelines was performed in the PubMed database of the studies describing the use of PTD screw fixation for HGLS. Clinical and radiological data were extracted and discussed. Study quality was assessed with the Oxford Centre for Evidence-Based Medicine Levels of Evidence. RESULTS: Seven studies were included and reviewed; all of them were level IV of evidence. Two of them had large case series comparing different surgical techniques: one concluded that PTD was associated with better clinical outcomes when compared with standard screw fixation techniques and the other suggesting that the clinical and radiological outcomes of PTD were similar to those when an interbody fusion (TLIF) technique was performed, but PTD was technically less challenging. The remaining five studies included small case series and case reports. All of them reported the successful useful of PTD with or without technical variations. CONCLUSIONS: Our review concludes, with limited level of evidence that PTD fixation is a safe and efficient technique for treating HGLS patients. It is technically less demanding than a circumferential fusion, even though proper screw insertion is more demanding than conventional pedicle screw fixation.