Long-term failure of dynamic rods used in full dynamic stabilization

Abstract

Objective: Dynamic stabilization systems, which prevent degeneration and deformation of the lumbar spine by limiting segmental movement, have been used with increasing frequency over the years and have become an alternative to spinal fusion surgery. For a standard dynamic stabilization and for the system to work fully, the mechanical structure and material selection must be developed together. Our aim in this study was to compare clinically and radiologically the cases in which dynamic screws and different types of dynamic rods were used. Materials and Methods: We retrospectively analyzed 57 patients who underwent surgery between 2012 and 2015 using dynamic transpedicular screw (Safinaz, Medikon) and dynamic rod [dream/agile/polyetheretherketone (PEEK)] systems. The patients were diagnosed following detailed neurological and radiological imaging examinations to determine the location of pain. Demographic data and visual analogue scale-oswestry disability index scores were obtained. Results: The patients consisted of 23 (40.4%) males and 34 (59.6%) females with a mean age of 63.3±12.0 years (range 51-83 years) at initial symptom onset. The mean duration of clinical symptoms of the patients was 9.6 months. The mean follow-up period was 49.12 months. A dynamic transpedicular screw system was used in all patients. After the 3rd year postoperatively, rod breakage was detected in 3 patients in the agile rod group (20%) and in 4 patients in the dream rod group (22.2%). In the PEEK rod group, there were no patients with rod breakage. Conclusion: The combination of dynamic pedicle screw and dynamic rod implants, obtained from the right material and properly designed, will be an important alternative among non-fusion dynamic implants, especially in patients with multi-segment degenerative disease.