Abstract and Introduction
Abstract
Study Design: Retrospective cohort study.
Objectives: The purpose of this study was to analyze the long-term results for patients with lumbar spinal stenosis (LSS) treated with dynamic stabilization (DS) and to consider how we can improve the results.
Summary of Background Data: Few studies have reported long-term outcomes of DS surgery for LSS with or without spondylolisthesis.
Methods: A single-center, single-surgeon consecutive series of LSS patients who underwent DS surgery with at least 5 years of follow-up were retrospectively reviewed. Twenty-seven patients were included in the LSS group and 38 patients in the spondylolisthesis group. Patient characteristics, operative data, radiographic parameters, clinical outcomes, and complications were analyzed at baseline and follow-up.
Results: In the LSS group, all radiographic parameters (e.g., disc height, segmental lordosis, segmental range of motion [ROM] at the index level and proximal adjacent level, global lordosis, and global ROM) were maintained well until the last follow-up. In the spondylolisthesis group, global lordosis decreased from 36.5° ± 8.2° to 32.6° ± 6.0° at the last follow-up (P = 0.039), and global ROM decreased from 22.1° ± 6.9° to 18.8° ± 7.1° at the last follow-up (P = 0.012). In both groups, back pain, leg pain, and Oswestry Disability Index scores showed significant and sustained improvements. Screw loosening occurred in three patients (11.1%) in the LSS group and five patients (13.2%) in the spondylolisthesis group. Symptomatic adjacent segment degeneration (ASD) occurred in two patients (7.4%) in the LSS group and three patients (7.9%) in the spondylolisthesis group.
Conclusion: Decompression and DS surgery for LSS with or without spondylolisthesis showed favorable long-term surgical outcomes with an acceptable rate of complications and ASD. However, an improved physiological DS system should be developed.
Level of Evidence: 4
Introduction
Decompression and spinal fusion are standard treatment techniques for degenerative spinal diseases. However, problems associated with rigid fixation have been reported, such as infection, instrumentation failure, and accelerated degeneration of adjacent segments.[1–5] An abnormal process that develops at mobile segments above or below a fused spinal segment is referred to as adjacent segment degeneration (ASD).
Dynamic stabilization (DS) surgery is an alternative option to rigid spinal fusion surgery for degenerative disease.[6] Dynesys (Zimmer Spine, Minneapolis, MN) is a pedicle screw-based DS system.[7] Preservation of motion after decompression was thought to enable movement similar to physiological motion. If adequate spinal stability is achieved, it could provide favorable surgical outcomes and minimize the development of ASD.[8] The preservation of spine motion may reduce stress at adjacent levels, as was verified in a cadaveric study.[9,10] Several short-term follow-up studies have reported good surgical results, including clinical and radiographic outcomes, for lumbar spinal stenosis (LSS) with or without spondylolisthesis.[11,12] However, long-term studies are limited.[13] Furthermore, some studies have reported that DS surgery did not provide significant benefits in terms of long-term outcomes.[14,15]
The purpose of this study was to analyze the long-term radiologic and clinical outcomes in patients with LSS with or without spondylolisthesis treated with DS and to consider how we can improve the results.