Background: there is some debate about isolated L4/5 fusion and its effect on L5/S1segment, especially in presence of preoperative L5/S1degeneration and its effect on the postoperative clinical outcome.
Aim of study: to evaluate the effect of isolated L4/5 fusion on radiological and clinical outcome in presence or absence of L5/S1degeneration.
Method: this is a comparative retrospective study between 2 groups of patients had L4/5 degenerative spondylolisthesis underwent standard isolated L4/5posterolateral fusion surgery; the first group had a preoperative L5/S1radiological degeneration while the second group showed no preoperative L5/S1degeneration. The minimum follow up period for those patients were 2 years.
Results: 41 patients were included in this study; first group included 17 patients associated with preoperative L5/S1degeneration and the second group included 24 patients with no L5/S1degeneration. There were no significant differences in clinical and radiological outcome between the two groups when compared at the final follow up. According to the radiological degeneration 4 (23.5%) patients of the first group showed accelerated degeneration while 3(12.5%) patients of the second group showed accelerated L5/S1degeneration. On the other hand 2 (11.8%) patients of the first group showed clinical L5/S1degeneration while 1(4.2%) patients of the second group showed clinical degeneration. There were no significant differences in accelerated degeneration when we compared the two groups.
Conclusion:L5/S1segment could be safely spared in cases of L4/5 fusion in the presence of preoperative L5/S1degeneration if the clinical symptoms are not correlated to the degeneration.