Spinal Stenosis: Clinical and Radiological Studies

Background : Lumbar spinal stenosis (LSS) causes back pain, leg pain and restricted walking ability. There is sometimes a coexisting degenerative spondylolisthesis (DS), where one vertebra has slipped anteriorly to the one below. LSS is the most common cause for spinal surgery, and the annual rate of surgery is increasing in Europe and the US. The original surgical method is decompression-alone, in which the surgeon resects just enough tissue to create space for the neural structures, while maintaining motion and stability between the vertebrae. Decompression with fusion is a more complex method in which a stabilising bone bridge is created at the decompressed level, usually supported by screws and rods. Aims : The primary aim of the thesis was to determine whether decompression-alone is sufficient, or if decompression with fusion generates better outcomes. A secondary aim, explored in paper IV, was to explore if patients with new radiological stenosis also had worse clinical outcome at two-year follow-up. Methods : All papers are based on the Swedish Spinal Stenosis Study, an RCT randomising 233 LSS patients with or without DS to decompression-alone or decompression with fusion. Clinical, radiological and health economical parameters were collected from baseline up to five years after surgery. In papers I-III, data were analysed according to randomisation. In paper IV, SSSS patients are analysed as a cohort, disregarding the original randomisation. Results : In papers I-III the fusion group had longer operating time, more perioperative bleeding and higher direct cost per procedure than decompression-alone. Two-year clinical outcomes did not differ between the groups, whereas at five years three secondary clinical outcomes were better for decompression-alone. The rate of new radiological stenosis at two-year MRI was higher in the fusion group. Reoperation rates did not differ between the groups. In paper IV no correlation was found between clinical outcomes and new radiological stenosis at two year follow-up. The presence of preoperative DS did not affect any of the results. Conclusion : In LSS surgery, decompression-alone should generally be the method of choice, with or without preoperative DS present. Findings of new radiological stenosis two years after spinal stenosis surgery may well be present also among asymptomatic individuals.