Introduction: Non-fusion dynamic stabilization systems have been recently applied in the management of degenerative lumbar spinal diseases. Through clinical and radiological results with favorable outcomes have been reported, the effect to the adjacent segment degeneration (ASD) after application of non-fusion dynamic stabilization system is still unclear. Therefore the authors compared the postoperative changes in facet degeneration at L4-5 after Dynesys system and trans-foraminal interbody fusion (TLIF).
Methods: The patients who underwent single level surgery at L4-5 with Dynesys system or TLIF were investigated. Of those, the patients who evaluated postoperative computed tomography (CT) of the lumbar spine after 12 months of operation were included. Facet degeneration was evaluated at each level (L1-2, L2-3, L3-4, L4-5 and L5-S1) and was graded into 0 to 3 according to the previous CT grade. The results between pre- and post-operation at the last evaluated on CT were compared.
Results: Dynesys group were included 15 patients (M:F = 6:9, mean age of 58.3 years) and TLIF group were 22 patients (M:F = 11:11, mean age of 60.9 years). Sex, age, preoperative facet grade was not different between two groups. The last CT scan was obtained 24.9 months in Dynesys group and 30.7 months in TLIF group (p=0.57). The pre-and post-operative facet CT grade in Dynesys group was changed; 1.2 to 1.4 at L1-2, 1.0 to 1.3 at L2-3, 1.1 to 1.5 at L3-4, 2.3 to 2.7 at L4-5, and 0.9 to 1.2 at L5-S1. The change at above segment (L3-4) and instrumented segment (L4-5) was statistically significantly degenerated in Dynesys group. In TLIF group, however, facet degeneration was developed in all lumbar segments including instrumented, above and below segments.
Conclusions: Non-fusion dynamic stabilization system might be delay the ASD compared to the fusion surgery. Dynesys system itself, however, has limit to prevent the ASD in above and instrumented segment. The further development of more physiological dynamic stabilization system must be considered.
Patient Care: The comparison study between non-fusion surgery and fusion surgery to degenerative lumbar disease will be improved the operative approach of dynamic stabilization system and developed the more physiological instruments.
Learning Objectives: To compare the postoperative changes in facet degeneration at L4-5 after Dynesys system and trans-foraminal interbody fusion (TLIF)