Dynesys dynamic stabilization-related facet arthrodesis

Area of Science:

• Spine surgery
• Orthopedics
• Biomedical engineering

Background:

• Dynamic stabilization devices aim to stabilize the spine while preserving motion.
• Reports suggest limited motion at instrumented levels after Dynesys dynamic stabilization (DDS).
• The causes and clinical impact of this limited motion are not fully understood.

Purpose of the Study:

• To investigate the incidence of unintended facet arthrodesis after DDS.
• To evaluate the clinical outcomes associated with unintended facet arthrodesis.
• To identify risk factors for unintended facet arthrodesis following DDS.

Main Methods:

• Retrospective study of 80 patients with 1- or 2-level lumbar spinal stenosis undergoing laminectomy and DDS.
• Analysis of medical records, radiological data (radiographs, MRI, CT), and clinical evaluations.
• Assessment of pain (VAS), disability (ODI), and functional scores (JOA); CT for facet arthrodesis; dynamic radiographs for range of motion.

Main Results:

• 54.3% of 70 patients (mean age 64.0) developed unintended facet arthrodesis at the DDS level after a mean 29.9-month follow-up.
• Patients with facet arthrodesis were older (mean 68.3 vs 58.5 years, p=0.009).
• Older patients (>60 years) had higher odds of facet arthrodesis (OR 12.42) and immobile segments (OR 2.96); no significant difference in clinical outcomes was observed.

Conclusions:

• Unintended facet arthrodesis occurs in over half of patients after 1- or 2-level DDS, especially in those over 60.
• Older age is a significant risk factor for developing unintended facet arthrodesis and immobile spinal segments.
• Despite the high incidence, unintended facet arthrodesis did not adversely affect clinical outcomes during the study period.