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Minimally invasive decompression versus open laminectomy for central stenosis of the lumbar spine: pragmatic comparative effectiveness study

BMJ 2015; 350 doi: (Published 01 April 2015) Cite this as: BMJ 2015;350:h1603
  1. Ulf S Nerland, neurosurgeon12,
  2. Asgeir S Jakola, neurosurgeon134,
  3. Ole Solheim, neurosurgeon124,
  4. Clemens Weber, neurosurgeon125,
  5. Vidar Rao, neurosurgeon12,
  6. Greger Lønne, orthopaedic surgeon26,
  7. Tore K Solberg, neurosurgeon78,
  8. Øyvind Salvesen, statistician9,
  9. Sven M Carlsen, endocrinologist910,
  10. Øystein P Nygaard, neurosurgeon125,
  11. Sasha Gulati, neurosurgeon12511
  1. 1Department of Neurosurgery, St Olavs University Hospital, Trondheim, Norway
  2. 2Department of Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway
  3. 3Department of Neurosurgery, Sahlgrenska University Hospital, Gothenburg, Sweden
  4. 4National Advisory Unit in Ultrasound and Image-Guided Surgery, St Olavs University Hospital, Trondheim, Norway
  5. 5National Advisory Unit on Spinal Surgery Center for Spinal Disorders, St Olavs University Hospital, Trondheim, Norway
  6. 6Department of Orthopedics, Innlandet Hospital Trust, Brumunddal, Norway
  7. 7Department of Neurosurgery, University Hospital of Northern Norway, Tromsø, Norway
  8. 8The Norwegian National Registry for Spine Surgery, University Hospital of Northern Norway), Tromsø, Norway
  9. 9Unit for Applied Clinical Research, Norwegian University of Science and Technology, Trondheim, Norway
  10. 10Department of Endocrinology, St Olavs University Hospital, Trondheim, Norway
  11. 11Norwegian Centre of Competence in Deep Brain Stimulation for Movement Disorders, St Olavs University Hospital, Trondheim, Norway
  1. Correspondence to: S Gulati Department of Neurosurgery, St Olavs University Hospital, 7006 Trondheim, Norway sashagulati{at}
  • Accepted 25 February 2015


Objective To test the equivalence for clinical effectiveness between microdecompression and laminectomy in patients with central lumbar spinal stenosis.

Design Multicentre observational study.

Setting Prospective data from the Norwegian Registry for Spine Surgery.

Participants 885 patients with central stenosis of the lumbar spine who underwent surgery at 34 Norwegian orthopaedic or neurosurgical departments. Patients were treated from October 2006 to December 2011.

Interventions Laminectomy and microdecompression.

Main outcome measures The primary outcome was change in Oswestry disability index score one year after surgery. Secondary endpoints were quality of life (EuroQol EQ-5D), perioperative complications, and duration of surgical procedures and hospital stays. A blinded biostatistician performed predefined statistical analyses in unmatched and propensity matched cohorts.

Results The study was powered to detect a difference between the groups of eight points on the Oswestry disability index at one year. 721 patients (81%) completed the one year follow-up. Equivalence between microdecompression and laminectomy was shown for the Oswestry disability index (difference 1.3 points, 95% confidence interval −1.36 to 3.92, P<0.001 for equivalence). Equivalence was confirmed in the propensity matched cohort and full information regression analyses. No difference was found between groups in quality of life (EQ-5D) one year after surgery. The number of patients with complications was higher in the laminectomy group (15.0% v 9.8%, P=0.018), but after propensity matching for complications the groups did not differ (P=0.23). The duration of surgery for single level decompression was shorter in the microdecompression group (difference 11.2 minutes, 95% confidence interval 4.9 to 17.5, P<0.001), but after propensity matching the groups did not differ (P=0.15). Patients in the microdecompression group had shorter hospital stays, both for single level decompression (difference 1.5 days, 95% confidence interval 1.7 to 2.6, P<0.001) and two level decompression (0.8 days, 1.0 to 2.2, P=0.003).

Conclusion At one year the effectiveness of microdecompression is equivalent to laminectomy in the surgical treatment of central stenosis of the lumbar spine. Favourable outcomes were observed at one year in both treatment groups.

Trial registration NCT02006901.


  • We thank the Norwegian Registry for Spine Surgery (NORspine). The registry receives funding from the University of Northern Norway and Norwegian health authorities. We thank all patients and spine surgeons who participate in NORspine registration.

  • Contributors: All authors read and approved the final manuscript. SG is the guarantor and originally conceived the study. USN and SG were involved in the study design, collection of data, statistical analysis, and writing of the manuscript. ASJ, ØS, and SMC took part in the study design, statistical analysis, and writing of the manuscript. OS and ØPN contributed to the study design and writing of the manuscript. CW, VR, GL, and TKS participated in the collection of data and writing of the manuscript.

  • Funding: This study received a grant (for quality improvement and patient safety) from the Norwegian Medical Association ( The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at and declare: all authors had financial support from the Norwegian Medical Association for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: This study was approved by the regional committee for medical research in central Norway (ID2013/643) and all participants provided written informed consent. The Data Inspectorate of Norway approved the registry protocol.

  • Data sharing: No additional data available.

  • Transparency: The lead author (SG) affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned have been explained.

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