1554. Dynamic Pedicle-Based Stabilization Versus Fusion in Lumbar Degenerative Instabilities: A Prospective Randomized Multicenter Double-Blind Trial (DYNORFUSE Trial)

Authors: Bernhard Meyer, MD; Claudius Thome, MD; Peter Vajkoczy, MD; Florian Ringel, MD (Munich, Germany)

Introduction: 360 0 fusion is a standard treatment for symptomatic degenerative lumbar instabilities, but is associated with relevant morbidity. Pedicle based dynamic stabilization may be an alternative to reduce surgical complexity. This prospective randomized double-blind trial tested the hypothesis of clinical non-inferiority of dynamic stabilization versus fusion for lumbar degenerative instabilities. Methods: Patients with symptomatic low grade lumbar degenerative disease (+/- stenosis) with either i) ≥5 mm spondylolisthese or segmental instability of ≥3 mm or 10 o in flexion/extension imaging and ii) failed conservative therapy for ≥3 months were randomized to TLIF fusion or dynamic stabilization in a 1:1 fashion. Primary endpoint was the between group difference in ODI 24 months after treatment. Patients and independent observers remained blinded to treatment allocation. Results: 301 patients were randomized at 17 centers to fusion (FU) or dynamic stabilization (DY). Baseline data were not different except for a non relevant difference in ODI of 45.8 ± 17.2 versus 42.5 ± 17.1 ( FU vs DY). Duration of surgery was significantly (p=0.007) shorter for DY (188 vs 231 min) with reduced blood loss (370 vs 491 cc) (p=0.038). ODI 24 months after treatment showed a significantly and clinically relevant reduction in both groups, without significant intergroup differences (30.8 ± 19.1 in FU versus 31.2 ± 18.1 in DY). Secondary outcome parameters also revealed no significant (p<0.05) differences between groups, such as the incidence of serious adverse events. Early revisions were necessary in 4 cases in DY and in 2 cases in FU. 24 months after surgery 34% vs 33% of patients had ongoing pain, 0% vs 3% (DY vs FU) underwent hardware revision. Conclusion: Dynamic pedicle-based stabilization is non-inferior to fusion in the treatment of low grade lumbar degenerative instabilities, but surgically less complex with secondary failures being not different between groups.