Complications of 2-level dynamic stabilization: A correlative clinical and radiological analysis at two-year follow-up on 103 patients

AIM: To investigate the postoperative complications, such as screw loosening, screw breakage and adjacent segment disease (ASD), in patients who underwent surgery with 2-level dynamic stabilization systems. MATERIAL and METHODS: Postoperative complications, clinical improvements and radiological parameters in patients who underwent surgery using a dynamic system for 2-level lumbar stabilization were retrospectively reviewed. A total of 103 patients with lumbar degenerative spinal instability underwent 2-level dynamic stabilization. Clinical findings were reviewed at 2-year follow-up. Screw breakage and loosening were evaluated during this duration together with clinical findings. RESULTS: Visual analog scale (VAS) and Oswestry Disability Index (ODI) scores were significantly decreased at the four-month evaluation, and they were also decreased at the 1-year follow up and at the 24th postoperative month. ASD was diagnosed in twelve (8 females, 4 males) of the 103 patients in the follow-up radiological and clinical controls. There were 9 screw breakages and 4 screw loosening cases. The complication rate of 2-level dynamic stabilization was high in this study. CONCLUSION: Our results showed that complications (screw loosening or breakage and adjacent segment disease) are not rare after 2-level dynamic stabilization, unlike the acceptable results with the single-level dynamic system. The most probable explanation is that the instrument system behaves more rigidly with every additional segment.