Clinical outcomes of degenerative lumbar spinal stenosis treated with lumbar decompression and the Cosmic “semi-rigid” posterior system

BACKGROUND Although some investigators believe that the rate of postoperative instability is low after lumbar spinal stenosis surgery, the majority believe that postoperative instability usually develops. Decompression alone and decompression with fusion have been widely used for years in the surgical treatment of lumbar spinal stenosis. Nevertheless, in recent years several biomechanical studies have shown that posterior dynamic transpedicular stabilization provides stabilization that is like the rigid stabilization systems of the spine. Recently, posterior transpedicular dynamic stabilization has been more commonly used as an alternative treatment option (rather than rigid stabilization with fusion) for the treatment of degenerative spines with chronic instability and for the prevention of possible instability after decompression in lumbar spinal stenosis surgery. METHODS A total of 30 patients with degenerative lumbar spinal stenosis (19 women and 11 men) were included in the study group. The mean age was 67.3 years (range, 40-85 years). Along with lumbar decompression, a posterior dynamic transpedicular stabilization (dynamic transpedicular screw-rigid rod system) without fusion was performed in all patients. Clinical and radiologic results for patients were evaluated during follow-up visits at 3, 12, and 24 months postoperatively. RESULTS The mean follow-up period was 42.93 months (range, 24-66 months). A clinical evaluation of patients showed that, compared with preoperative assessments, statistically significant improvements were observed in the Oswestry and visual analog scale scores in the last follow-up control. Compared with preoperative values, there were no statistically significant differences in radiologic evaluations, such as segmental lordosis angle (α) scores (P = .125) and intervertebral distance scores (P = .249). There were statistically significant differences between follow-up lumbar lordosis scores (P = .048). There were minor complications, including a subcutaneous wound infection in 2 cases, a dural tear in 2 cases, cerebrospinal fluid fistulas in 1 case, a urinary tract infection in 1 case, and urinary retention in 1 case. We observed L5 screw loosening in 1 of the 3-level decompression cases. No screw breakage was observed and no revision surgery was performed in any of these cases. CONCLUSIONS Posterior dynamic stabilization without fusion applied to lumbar decompression leads to better clinical and radiologic results in degenerative lumbar spinal stenosis. To avoid postoperative instability, especially in elderly patients who undergo degenerative lumbar spinal stenosis surgery with chronic instability, the application of decompression with posterior dynamic transpedicular stabilization is likely an important alternative surgical option to fusion, because it does not have fusion-related side effects, is easier to perform than fusion, requires a shorter operation time, and has low morbidity and complication rates.