Oral Presentation 51st International Society for the Study of the Lumbar Spine Annual Meeting 2025

Adjacent level canal area changes up to 2 years after lumbar spinal stenosis decompressive surgery  - a secondary analysis of data from the NORDSTEN SST study (114249)

Helena Brisby 1 2 , Tor Åge Myklebust 3 4 , Hasan Banitalebi 5 6 , Ivar Austevoll 7 , Jorn Aaen 8 9 , Kjersti Storheim 10 11 , Christian Hellum 12 , Eric Franssen 13 , Kari Indrekvam 7 14 , Erland Hermansen 4 15
  1. Institute of Clinical Sciences , Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
  2. Department of Orthopedics, Sahlgrenska University Hospital, Gothenborg, Sweden.
  3. Department of Registration, Cancer Registry Norway, Oslo, Norway
  4. Department of Research and Innovation, Møre and Romsdal Hospital Trust, Ålesund,, Norway
  5. Department of Diagnostic Imaging, Akershus University Hospital,, Lorenskog, Norway
  6. Institute of Clinical Medicine, University of Oslo,, Oslo, Norway.
  7. Kysthospitalet in Hagevik, Orthopedic Department, Haukeland University Hospital,, Bergen, Norway
  8. Department of Orthopaedic Surgery, Ålesund Hospital, Møre and Romsdal Hospital Trust, Ålesund, Norway
  9. Department of Circulation and Medical Imaging, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
  10. Research and Communication Unit for Musculoskeletal Health, Division of Clinical Neuroscience, Oslo University Hospital, Oslo, Norway
  11. Department of Physiotherapy , Oslo Metropolitan University, Oslo , Norway
  12. Division of Orthopedic Surgery , Oslo University Hospital Ullevål, Oslo , Norway
  13. Orthopedic department, Stavanger University Hospital, Stavanger , Norway
  14. Department of Clinical Medicine, University of Bergen, Bergen, Norway
  15. Institute of Health Sciences, Norwegian University of Technology and Science, Ålesund, Norway

 

INTRODUCTION

Decompressive surgery for LSS is currently the most common spinal surgery procedure; however, there is limited knowledge on changes in the DSCA over time adjacent to a decompressed segment.  The aim of the present study was to investigate whether the dural sac cross-sectional area (DSCA) on magnetic resonance imaging (MRI) of adjacent segments decreases after decompressive surgery due to lumbar spinal stenosis (LSS) up to 2 years postoperatively, and to investigate possible associations with baseline variables, including preoperative patient and radiological characteristics, and surgical method used.


METHODS

This was a secondary analysis of data from the NORDSTEN-spinal stenosis trial (SST) where 437 patients were randomized to decompression with one of three minimally invasive surgical methods for LSS. The patients underwent MRI of the lumbar spine (L2-L5) before surgery and at 3 and 24 months postoperatively. Descriptive statistics of adjacent DSCA and changes in adjacent DSCA are presented. Possible prognostic factors (preoperative factors, radiological measures, and surgical method) for changes in the adjacent DSCA were examined using multivariate regression analyses.

 


RESULTS

322 patients (74%) in the original NORDSTEN-SST had undergone MRI at both 3 and 24 months postoperatively and were included (360 adjacent levels, 263 cranial, and 97 caudal to a decompressed level). Up to 2 years postoperatively, no decrease in adjacent DSCA was observed (see Figure 1). No associations were found between the investigated baseline variables, and DSCA change from 0 to 2 years, except for a weak association with baseline adjacent DSCA. The same but no other associations were found for the subgroup of patients with a decrease of adjacent DSCA of > 1SD.


DISCUSSION

Up to 2 years postoperatively, the DSCA did not decrease at adjacent levels after decompressive surgery. None of the investigated baseline variables showed any clinical meaningful prognostic value regarding adjacent DSCA changes 2 years postoperatively. The findings support previous reports that decompression of adjacent levels is not required to prevent subsequent stenosis.

671fa2a81d7a2-Figure+1+ISSLS+d.png