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)


3600fusion 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.


Patients with symptomatic low grade lumbar degenerative disease (+/- stenosis) with either i) ≥5 mm spondylolisthese or segmental instability of ≥3 mm or 10oin 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.


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.


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.