To Include S1 Screws or Not in Fixation of L4-5 Spondylolisthesis Associated with L5-S1 Degenerative Disc Disease

Background: The main goal of management of L4-5 spon-dylolisthesis is reduction and fixation of the mobile vertebrae to reduce back pain and relief neurological compression. If the pa-tient has in addition, L5-S1 degenerative disc, there is always a debate about including S1 vertebra in the fusion surgery or not. Aim of Study: To compare the L4-5 fusion (floating fusion) and the L4-5-S1 fusion (sacral fusion) in the surgical manage-ment of L4-5 spondylolisthesis associated with degenerative L5-S1 disc as regard outcome and complications of both tech-niques. Patients and Methods: The study included 60 patients hav-ing L4-5 spondylolisthesis associated with L5-S1 degenerative disc. Patients were followed-up clinically and radiologically for at least 6 months. Data were collected and statistically calcu-lated. Results: Thirty patients were operated for L4-5 fusion and 30 patients were operated for L4-5-S1 fusion. Sacroiliitis was highly significant in group that underwent sacral fusion than group with floating fusion. 40% of patients operated for sacral fusion were complicated by sacroiliitis, while only 16% in pa-tients operated for floating fusion. The group that had sacral fusion reported higher adjacent segment disease 30% than the group that had floating fusion 23%. Sacroiliitis was reported more in female patients where 70% of sacroiliitis cases were females. Adjacent segment disease occurred more in females, 62.5% of cases with adjacent segment disease are in female patients. Sacroiliitis was significantly affected by Body mass index, as the mean BMI among patients with sacroiliitis was 31±2 compared to 29±2 among patients without sacroiliitis. The mean BMI for patients with adjacent segment disease was 31.44±1.22, while the mean BMI for patients without adjacent segment disease was 28.67±2.73, this significantly indicates a relation between increasing in body mass index and occurrence of ASD. Conclusion: L4-5-S1 fixation carries more risk of occur-rence of sacroiliitis and ASD than isolated L4-L5 fixation.