Study design: A systematic medline review.
Objective: An overview of pedicle-based dynamic stabilization devices clinical outcomes.
Summary of background data: Fusion is the standard instrumentation for many pathologies of the lumbar spine. Worrying rates of failure, including adjacent segment degeneration (ASD), have consistently been reported. The interest for dynamic stabilization came from the need of minimizing the long-term complications related to the restriction of the lumbar motion. However, pedicle-based dynamic stabilization advantages and drawbacks remain controversial.
Materials and methods: Articles about the clinical outcomes were identified by a comprehensive Medline search. The inclusion criteria were a minimum follow-up of 12 months, indications for lumbar dynamic stabilization, and assessment of clinical outcomes and adverse events. The studied parameters included self-reported outcomes (pain, disability, and satisfaction) and complications.
Results: A total of 46 articles fulfilling the inclusion criteria were reviewed providing results for 2026 patients with a mean follow-up of 33 months. The postoperative improvements in terms of pain and disability were significant. Subjective assessment showed an overall patient satisfaction of 83.4%. Radiographic ASD occurred in 0%-34% of patients. Device breakage occurred in 0%-30%, and device loosening in 0%-72% of patients. The global amount of revision surgeries reached 9.4% mainly for breakage, ASD, or persistent pain, not always associated with screw loosening.
Conclusions: Dynamic stabilization seems as safe and effective but benefits might partly come from decompressive gestures. Reported clinical outcomes seems to be comparable with outcomes published for fusion and no clear evidence of protection of the adjacent segments emerge from this mid-term review. Technical failures are design related but also linked with patient specificities. Relationships between sagittal balance and surgery outcomes are still rarely reported. Dynamic stabilization might display advantages in selected indications, such as moderate degeneration and beginning instability associated with clinical symptoms, but further clinical studies are needed.