Study design: This retrospective study analyzed the outcome of 44 patients who had decompression, pedicle screw-rod fixation, and fusion for Grades 1 and 2 spondylolytic spondylolisthesis.
Objective: To evaluate the outcome of two methods for stabilization and fusion: posterolateral fusion and circumferential fusion involving posterior lumbar interbody fusion and posterolateral fusion for low grades of isthmic spondylolisthesis.
Summary of background data: It has been suggested that stabilization with instrumented fusion is somewhat unpredictable due to lack of anterior support. Does circumferential fusion using posterior lumbar interbody fusion circumvent all the problems, and is it better than posterolateral fusion clinically?
Methods: A single surgeon treated 21 patients with instrumented posterolateral fusion and 23 patients with instrumented circumferential fusion, (i.e., posterior lumbar interbody fusion, and posterolateral fusion. These two groups were compared for clinical outcome, fusion rate, and correction of slippage.
Results: The minimum follow-up period for the patients was 2.1 years. The clinical satisfactory outcome on the Oswestry index was 81% for posterolateral fusion and 69% for posterior lumbar interbody fusion. The subjective outcome was 86% and 65%, respectively, for the two groups (P > 0.05). However, a consideration of subjective scores showed that three patients (14.3%) in posterolateral fusion group and eight patients (34.8%) in posterior lumbar interbody fusion group had an unsatisfactory outcome (P = 0.0135), which was very significant. There were two nonunions in the posterolateral fusion group and none in the posterior lumbar interbody fusion group (P > 0.05). The correction of slippage and the loss of correction at the last follow-up assessment was better in the posterior lumbar interbody fusion group, although this was not statistically significant (P > 0.05). Radicular symptoms and neurologic improvement were statistically similar between the two groups.
Conclusions: Posterolateral fusion has a better clinical outcome in low grades of isthmic spondylolisthesis, although posterior lumbar interbody fusion is more predictable in maintaining correction and achieving union. Careful patient selection is needed for each operation, and adjacent level disc degeneration may influence the procedure offered to the patient.