Literature Decoded

Living reprintoriginally published in JAMA Network Open 2022CC BY 4.0Read the version of record Opt out

Literature DecodedLiving reprint
Living reprint · journal article Journal version available

Comparison of 3 Different Minimally Invasive Surgical Techniques for Lumbar Spinal Stenosis: A Randomized Clinical Trial

Randomised trial first published in JAMA Network Open (2022), reprinted in full under its CC BY 4.0 licence.

Erland Hermansen1*, Ivar Magne Austevoll2, Christian Hellum3, Kjersti Storheim4, Tor Åge Myklebust5, Jørn Aaen6, Hasan Banitalebi7, Masoud Anvar8, Frode Rekeland2, Jens Ivar Brox9, Eric Franssen10, Clemens Weber11, Tore K. Solberg12, Håvard Furunes13, Oliver Grundnes14, Helena Brisby15, Kari Indrekvam16

1Department of Orthopedic Surgery, Ålesund Hospital, Møre and Romsdal Hospital Trust, Ålesund, Norway; Kysthospitalet in Hagevik, Orthopedic Clinic, Haukeland University Hospital, Bergen, Norway; Department of Clinical Medicine, University of Bergen, Bergen, Norway; Hofseth BioCare, Ålesund, Norway2Kysthospitalet in Hagevik, Orthopedic Clinic, Haukeland University Hospital, Bergen, Norway3Division of Orthopedic Surgery, Oslo University Hospital Ullevål, Oslo, Norway4Communication and Research Unit for Musculoskeletal Health (FORMI), Oslo University Hospital, Oslo, Norway5Department of Research and Innovation, Møre and Romsdal Hospital Trust, Ålesund, Norway; Department of Registration, Cancer Registry Norway, Oslo, Norway6Department of Orthopedic Surgery, Ålesund Hospital, Møre and Romsdal Hospital Trust, Ålesund, Norway; Department of Circulation and Medical Imaging, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway7Department of Diagnostic Imaging, Akershus University Hospital, Oslo, Norway; Institute of Clinical Medicine, University of Oslo, Oslo, Norway8Unilabs Radiology, Oslo, Norway9Department of Physical Medicine and Rehabilitation, Oslo University Hospital, Oslo, Norway10Department of Orthopedics, Stavanger University Hospital, Stavanger, Norway11Department of Orthopedics, Stavanger University Hospital, Stavanger, Norway; Department of Neurosurgery, Stavanger University Hospital, Stavanger, Norway; Department of Quality and Health Technology, University of Stavanger, Stavanger, Norway12Department of Neurosurgery and the Norwegian Registry for Spine Surgery, University Hospital of Northern Norway, Tromsø, Norway; Institute of Clinical Medicine, The Arctic University of Norway, Tromsø, Norway13Department of Surgery, Gjøvik Hospital, Innlandet Hospital Trust, Brumunddal, Norway; Institute of Health and Society Studies, University of Oslo, Oslo, Norway14Department of Orthopedics, Akershus University Hospital, Oslo, Norway15Department of Orthopedics, Sahlgrenska University Hospital, Gothenburg, Sweden; Department of Orthopedics, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden16Kysthospitalet in Hagevik, Orthopedic Clinic, Haukeland University Hospital, Bergen, Norway; Department of Clinical Medicine, University of Bergen, Bergen, Norway*Corresponding author

Reprinted 2026-10-01 20 min read Living reprint · journal article Version of record: JAMA Network Open 2022Licence: CC BY 4.0

Reading mode
In plain languageRandomised trial first published in JAMA Network Open (2022), reprinted in full under its CC BY 4.0 licence.

Randomised trial first published in JAMA Network Open (2022), reprinted in full under its CC BY 4.0 licence.

No plain-language summary has been written for this reprint yet. The authors' abstract and full text follow, unchanged apart from layout.

Educational summary of research findings; not medical advice. Discuss care decisions with a qualified clinician.

Bottom line

What the evidence supports

How to read it

No plain-language summary has been written for this reprint yet. The authors' abstract and full text follow, unchanged apart from layout.

Limitations

The findings apply to the included study populations and may not generalise to every person or setting.

Disclaimer

Educational summary of research findings; not medical advice. Discuss care decisions with a qualified clinician.

The paper

Full manuscript

Abstract

Importance

Operations for lumbar spinal stenosis is the most often performed surgical procedure in the adult lumbar spine. This study reports the clinical outcome of the 3 most commonly used minimally invasive posterior decompression techniques.

Objective

To compare the effectiveness of 3 minimally invasive posterior decompression techniques for lumbar spinal stenosis.

Design, Setting, and Participants

This randomized clinical trial used a parallel group design and included patients with symptomatic and radiologically verified lumbar spinal stenosis without degenerative spondylolisthesis. Patients were enrolled between February 2014 and October 2018 at the orthopedic and neurosurgical departments of 16 Norwegian public hospitals. Statistical analysis was performed in the period from May to June 2021.

Interventions

Patients were randomized to undergo 1 of the 3 minimally invasive posterior decompression techniques: unilateral laminotomy with crossover, bilateral laminotomy, and spinous process osteotomy.

Main Outcomes and Measures

Primary outcome was change in disability measured with Oswestry Disability Index (ODI; range 0-100), presented as mean change from baseline to 2-year follow-up and proportions of patients classified as success (>30% reduction in ODI). Secondary outcomes were mean change in quality of life, disease-specific symptom severity measured with Zurich Claudication Questionnaire (ZCQ), back pain and leg pain on a 10-point numeric rating score (NRS), patient perceived benefit of the surgical procedure, duration of the surgical procedure, blood loss, perioperative complications, number of reoperations, and length of hospital stay.

Results

In total, 437 patients were included with a median (IQR) age of 68 (62-73) years and 230 men (53%). Of the included patients, 146 were randomized to unilateral laminotomy with crossover, 142 to bilateral laminotomy, and 149 to spinous process osteotomy. The unilateral laminotomy with crossover group had a mean change of −17.9 ODI points (95% CI, −20.8 to −14.9), the bilateral laminotomy group had a mean change of −19.7 ODI points (95% CI, −22.7 to −16.8), and the spinous process osteotomy group had a mean change of –19.9 ODI points (95% CI, −22.8 to –17.0). There were no significant differences in primary or secondary outcomes among the 3 surgical procedures, except a longer duration of the surgical procedure in the bilateral laminotomy group.

Conclusions and Relevance

No differences in clinical outcomes or complication rates were found among the 3 minimally invasive posterior decompression techniques used to treat patients with lumbar spinal stenosis.

Trial Registration

ClinicalTrials.gov Identifier: NCT02007083

Introduction

Symptomatic lumbar spinal stenosis (LSS) is characterized by pain and discomfort in the lower back and the lower extremities, impaired walking ability, and functional disability. Imaging shows a narrowing of the lumbar spinal canal.1 LSS is a common condition involving a large patient group who are treated by several medical specialties involved in different aspects of the diagnosis and treatments. Several studies2,3,4,5 have shown superior clinical results after surgical treatment compared with nonsurgical treatment. The surgical procedure for LSS is the most frequently performed procedure in the adult lumbar spine.6,7

A posterior decompression at the level of the stenosis is usually performed, and an open laminectomy has been considered the reference standard.8,9 Less invasive, midline retaining, posterior decompression techniques have been introduced in the last decades. They have shown similar effectiveness as traditional laminectomies, but the duration of the surgical procedure and length of hospital stay is usually shorter because of the less invasive nature of the procedure.10

Various midline retaining techniques have been introduced with scarce scientific evidence regarding the possible advantages and disadvantages. Therefore an effectiveness study of different minimally invasive techniques would be of interest for the medical community and health care planning and allocation of resources. This trial investigates the outcome after 3 commonly used methods that differ in spinal canal access and may differ in surgical radicality.

Some former trials11,12,13,14,15,16,17 show comparable clinical results after different posterior decompression techniques. However, 2 Cochrane reviews, Overdevest et al8 and Machado et al,18 and an umbrella review by Jacobs et al19 concluded that the scientific evidence is of low quality and that high-quality research is required before a scientific conclusion can be reached. This trial aims to investigate whether 1 of the 3 most commonly used minimally invasive posterior decompression techniques is superior in the treatment of LSS with respect to clinical outcomes.

Methods

The Norwegian Degenerative Spondylolisthesis and Spinal Stenosis study (NORDSTEN study) consists of 2 randomized clinical trials, including the NORDSTEN Spinal Stenosis Trial (SST). The SST is a multicenter trial where orthopedic and neurosurgical departments of 16 hospitals participated. The study protocol was prepared according to the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) reporting guideline.20 The protocol is also attached in Supplement 1. The trial was registered at ClinicalTrials.gov (NCT02007083). Ethics approval was given by the Regional Committee for Medical and Health Research Ethics of Central Norway. This randomized clinical trial is reported according to the Consolidated Standards of Reporting Trials (CONSORT) reporting guideline.21 The trial was also monitored according to a modified version of the International Conference on Harmonization Guideline for Good Clinical Practice (ICH-GCP),22 and a monitor-report is provided in eAppendix 1 in Supplement 2. A patient representative from the Norwegian Back Association has been a permanent member of both the Scientific Steering Committee and the Working Committee of the NORDSTEN-study (eAppendix 2 in Supplement 2). Informed consent was collected in a paper-based form and was stored in a fire proof safe at each of the study centers according to Norwegian rules for conducting clinical trials.

Inclusion Process and Patient Recruitment

Patients with symptoms of LSS and corresponding magnetic resonance imaging findings were eligible for inclusion in the trial. An orthopedic or neurosurgical surgeon assessed the participants at 1 of the 16 participating hospitals between February 2014 and October 2018. Patients with degenerative spondylolisthesis were excluded. Eligibility criteria are presented in the eTable 1 in Supplement 2. Initially, patients were excluded from February 2014 to October 2015 if their Oswestry Disability Index (ODI) at baseline was less than 25 points. The removal of this exclusion criterion was done to increase the external pragmatism and validity of the study. An amendment was sent to the ethics authorities, and the amendment was also registered in ClinicalTrials.gov and in the published protocol.20

Randomization and Masking

Patients who provided informed consent were randomized to 1 of the 3 different posterior decompression techniques. The randomization (ie, 1:1:1 allocation) was performed within 6 weeks before the surgical procedure. We used a block randomization design, stratified by 16 hospitals, with the blocks being made as small as possible (randomly selected block size 3 and 6) to ensure that every hospital performed similar amount of all 3 procedures. The randomization procedure was concealed (computer-generated) and administered by the NORDSTEN-study coordination center located at the Communication and Research Unit for Musculoskeletal Health, Oslo University Hospital, Oslo, Norway. Output information regarding allocation was emailed to the local study coordinator, who was not involved in the recruitment or treatment of patients and registered in the patient record. The patients were not blinded to the treatment group; they were informed that none of the treatment options were documented as superior to the other.

Surgical Techniques

All surgeons were familiar with the 3 techniques through previous experience, the surgical protocol, and joint demonstration operations were performed before initiating the study (Figure 1). The surgical target level was confirmed by intraoperative fluoroscopic guidance. When performing unilateral laminotomy with crossover (UL), loupe magnification, or surgical microscope was mandatory, while in bilateral laminotomy (BL) and spinous process osteotomy (SPO) the use of loupes or microscope was optional depending on the surgeon’s preference. The surgeons were instructed to visualize the respective medial borders of the pedicles and the nerve roots from the beginning of the thecal sac passing the pedicle.

Figure 1.. Before and After the Surgical Procedure for Lumbar Spinal Stenosis With the 3 Different Minimally Invasive Decompression Techniques Used in the Study
Figure 1.. Before and After the Surgical Procedure for Lumbar Spinal Stenosis With the 3 Different Minimally Invasive Decompression Techniques Used in the Study

UL With Crossover

An ipsilateral flavectomy was performed followed by a laminotomy of the lower part of the superior lamina and the upper part of the inferior lamina.23 Laterally, a medial facetectomy was performed, and the patient was then slightly rotated to visualize the contralateral side. The dura was retracted, and the decompression was performed contralaterally.

BL

A bilateral flavectomy was performed followed by a bilateral laminotomy of the lower part of the superior lamina and the upper part of the inferior lamina. Laterally, a medial facetectomy was performed.24

SPO and Decompression

An osteotomy was performed at the base of the spinous process above and sometimes below the affected level.25 The spinous process was retracted to the contralateral side with intact supraspinal and interspinal ligaments to access and decompress the spinal canal in the midline. A laminotomy of the lower part of the superior lamina and the upper part of the inferior lamina was performed followed by a medial facetectomy. Both nerve roots were visualized, and the lateral recesses were decompressed. Special attention was warranted when a multilevel decompression was performed to preserve at least one-third of the lamina.

Primary Outcome

The primary outcome measure was change in disability measured with Oswestry Disability Index (ODI, version 2.0) from baseline to 24 months after the surgical procedure. ODI is a widely used and validated pain and function score, where 0 is considered asymptomatic and 100 is considered completely disabled.26,27 The patients completed the questionnaires, including ODI, before the surgical procedure and at 3, 12, and 24 months after the surgical procedure. The mean score change from baseline to 2-year follow-up was compared between the 3 groups. Additionally, patient outcomes were classified as a success if they had a 30% reduction of baseline ODI, and the proportion of patients classified as a success in each group were determined at the different follow-up time points.28,29

Secondary Outcomes

Secondary patient-reported outcomes were changes from baseline to follow-up in the EuroQol 5-dimensional questionnaire utility index (EQ-5D), the Zurich Claudication Questionnaire (ZCQ-score), a 10-point numeric rating scale (NRS) for low back pain and leg pain, and a global perceived effect (GPE)-scale.

The EQ-5D is a generic quality-of-life questionnaire, ranging from −0.59 (ie, worst possible) to 1.00 (ie, best possible). This questionnaire was validated for the Norwegian population.30 The 3-level version of EQ-5D and the corresponding UK value set to calculate scores was used.

The ZCQ is a disease-specific questionnaire for LSS and includes symptom severity, physical activity, and patient satisfaction during follow-up. Answers range from 1.0 to 5.0 in the symptom severity scale.31 In the physical activity scale, the range is from 1.0 to 4.0. The patient satisfaction scale was answered postoperatively and ranged from 1.0 to 4.0. For all scales, 1.0 is the best option.

The NRS scores for leg and low back pain are validated parameters for clinical trials.32 The range is from 0 to 10, where 0 is no pain, and 10 is the worst pain imaginable.

The global perceived effect (GPE) scale is a 7-point score, which is recommended for clinical trials of chronic pain conditions.33 It has 7 response categories: 1, completely recovered; 2, much improved; 3, slightly improved; 4, no change; 5, slightly worse; 6, much worse; 7, worse than ever.

Surgical data defined as secondary outcomes were duration of the procedure, perioperative bleeding volume, complications, number of reoperations, and length of hospital stay. All primary and secondary outcomes data were administered by paper-based patient-reported questionnaires and case report form. The data were obtained from the patient and an independent study coordinator at each hospital, and the data was registered electronically by the study coordinating center.

Statistical Analysis

The trial was conducted with a superiority design to detect a difference in mean change of ODI from baseline to 2-year follow-up of 7 points between any groups. Because this requires 3 tests, the significance level was lowered from the standard P = .05 to P = .02. With an assumed SD of 18, 80% power, and a dropout rate of 15%, the sample size estimation recommended 155 patients in each group and 465 total. However, inclusion was stopped after reaching 437 patients because of the low rate of inclusion in the last months of the inclusion period. At that time, we had reports that the dropout rate was lower than anticipated, ensuring a sufficient number of participants in the statistical analysis.

Standard descriptive statistics were presented as absolute and relative frequencies for categorical variables, as mean (SD) for continuous variables, and as median (IQR) if skewed. Normal distribution was determined by visual inspection of histograms and qq-plots. Outcomes were analyzed by estimating multilevel linear models, including a random intercept for operating hospitals to account for the multicenter design. Continuous outcomes were analyzed using multilevel linear regressions, adjusting for baseline measurement if the outcome was a change score, and proportions were analyzed using multilevel Poisson regressions and adjusted for baseline measurement where appropriate. Predicted marginal effects, with corresponding 95% CIs were presented for all outcomes for all study arms. Actual means with corresponding 95% CIs were also presented graphically, along with standard t tests, as outlined in a published study protocol. Potential interaction effects were analyzed by including interaction terms between study arms and the variable of interest, tested using likelihood ratio tests, and comapred models with and without interaction effects. Complete case analyses were prefered because the proportion of missing observations rarely exceeded 10%. To assess the robustness of the results, we also analyzed the primary outcome after imputing missing data using multiple imputations with chained equations, including study arm, patients’ age, sex, body mass index (BMI; calculated as weight in kilograms divided by height in meters squared), and smoking status as factors in the imputation models.

Analyses were performed following the intention-to-treat principle (ITT). As 386 of 393 (98%) of the study participants that were eligible for analyses (ie, had necessary measurements of ODI at baseline and 2-year follow-up), were treated according to randomization, per-protocol analyses were deemed unnecessary. All analyses were executed by a statistician (T.Å.M.) blinded to the treatment given. Statistical analyses were performed using Stata Statistical Software version 17 (StataCorp). Two-sided t tests were used for the calculation of P values, and statistical significance was set at P = .02 for the primary outcome. Statistical analyses were performed in the period from May to June 2021.

Results

Baseline Data

Baseline characteristics are given in Table 1. Median (IQR) age in the total cohort was 68 (62-73) years with a mean (SD) BMI of 27.8 (4.2) and included 230 men (53%) and 87 individuals (21%) who smoked. The mean (SD) pain and function scores at baseline for the whole cohort were ODI, 38.4 (14.5); EQ-5D, 0.38 (0.32); ZCQ symptoms, 3.4 (0.6); ZCQ function, 2.5 (0.5); NRS leg pain, 6.5 (2.0); and NRS low back pain, 6.3 (2.2).

Table 1.. Postrandomization Baseline Characteristics, Patient-Reported Outcome Measures, and Number of Levels of the Patients Included in the 3 Study Groups
CharacteristicNo./total no. (%)
UL (n = 146)BL (n = 142)SPO (n = 149)
Age, median (IQR), y69 (64-74)67 (60-74)68 (61-72)
Sex
Female73/146 (50.0)78/142 (54.9)55/149 (36.9)
Male73/146 (50.0)63/142 (45.1)94/149 (63.1)
Higher level of educationa45/138 (32.6)35/138 (25.4)39/141 (27.7)
Smoking23/138 (16.7)34/139 (24.5)30/141 (21.3)
BMI, mean (SD)28.1 (4.2)27.7 (3.9)27.5 (4.4)
Former surgical procedure11/133 (8.3)10/133 (7.5)8/134 (6.0)
Duration of leg pain >1 y92/135 (68.2)94/131 (71.8)88/130 (67.7)
Duration of back pain >1 y109/134 (81.3)107/136 (78.7)105/139 (75.5)
Use of analgesics24/139 (17.3)36/138 (26.1)48/137 (35.0)
ASA score
111/137 (8.0)26/137 (19.0)12/137 (8.8)
296/137 (70.1)86/137 (62.8)98/137 (71.5)
330/137 (21.9)25/137 (18.3)27/137 (19.7)
HSCL-25, median (IQR)1.5 (1.2-1.9)1.6 (1.3-1.9)1.5 (1.3-1.8)
ODI, mean (SD)b38.5 (14.9)40.2 (14.1)36.6 (14.3)
ZCQ, mean (SD)
Symptom severity3.4 (0.5)3.4 (0.6)3.3 (0.5)
Physical activity2.5 (0.5)2.6 (0.5)2.5 (0.5)
NRS, median (IQR)c
Leg pain7 (5-8)7 (5-8)7 (5-8)
Back pain7 (5-8)7 (5-8)7 (5-8)
EQ-5D, mean (SD)0.37 (0.33)0.35 (0.31)0.40 (0.30)
Level of surgical procedure
180/135 (59.3)82/136 (60.3)82/134 (61.2)
253/135 (39.3)49/136 (36.0)46/134 (34.3)
32/135 (1.5)5/136 (3.7)6/134 (4.5)

Abbrevations: ASA, American Society of Anesthesiologists; BL, bilateral laminotomy; BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); EQ-5D, EuroQol 5-dimensional questionnaire utility index; HSCL: number of patients operated in a different level; HSCL-25, Hopkins Symptom Checklist-25; NRS, Numerical Rating Scale, which ranges from 0 (no pain) to 10 (worst pain imaginable); ODI, Oswestry Disability Index; SPO, spinous process ostetomy; UL, unilateral laminotomy with crossover; ZCQ, Zurich Claudication Questionnaire.

a 3 years or more in college or university.

b ODI ranges from 0 (no impairment) to 100 (the greatest impairment).

c NRS, Numerical Rating Scale ranges from 0 (no pain) to 10 (worst pain imaginable).

Of 2227 patients assessed for eligibility in the NORDSTEN-study, 1387 were eligible for inclusion in the SST, 950 did not fulfill all eligibility criteria and were excluded, and 437 underwent randomization. Figure 2 presents the study.34

Figure 2.. Study Flowchart
Figure 2.. Study Flowchart ASA indicates American Society of Anesthesiologists; CRF, case report form; NORDSTEN, Norwegian Degenerative Spondylolisthesis and Spinal Stenosis study; ODI, Oswestry Disability Index; SST, Spinal Stenosis Trial. aMore than 1 exclusion criteria were noted.

Primary Outcome

The actual mean change in ODI from baseline to 2-year follow-up for the whole cohort was −19.1 (95% CI, −20.8 to −17.5). The overall proportion of patients whose outcomes were classified as a success was 273 (69.5%). When adjusting for baseline ODI and operating hospital, the estimated mean change in ODI after 2 years was −17.8 (95% CI, −20.3 to −15.3) for the UL group, −18.7 (95% CI, −21.3 to −16.0) for the BL group and −21.0 (95% CI, −23.5 to −18.4) for the SPO group (Table 2). There were no statistically significant differences between the 3 surgical method groups in the primary outcome (P = .214). The mean ODI-score in each of the 3 surgical groups from baseline to 3, 12, and 24 months of follow-up appear in Figure 3 and eTable 2 in Supplement 2. Imputing missing data, the estimated mean (SD) changes in ODI for UL, BL, and SPO were −18.1 (95% CI, −20.7 to −15.6) points, −18.6 (95% CI, −21.1 to −15.9) points, and −21.2 (95% CI, −23.7 to −18.6) points, respectively. Analyzing interaction effects between study arms and period of inclusion, level of the surgical procedure, and number of levels operated did not show any evidence of differential effects of surgical technique in these subgroups of patients (eTable 7 in Supplement 2).

Table 2.. Primary and Secondary Outcomesa
OutcomesMean (95% CI)P valueNo. eligible for analyses
Unilateral laminotomy with crossoverBilateral laminotomySpinous process osteotomy
Primary outcome
Change in ODI after 24 mo−17.8 (−20.3 to −15.3)−18.7 (−21.3 to −16.0)−21.0 (−23.5 to −18.4).21393
Secondary outcomes
Proportion success after 24 mo, %67.4 (53.6 to 81.3)67.5 (53.1 to 81.8)73.5 (58.9 to 88.1).80393
Change in global EQ-5D score0.31 (0.26 to 0.37)0.31 (0.26 to 0.36)0.35 (0.30 to 0.40).54358
Change in ZCQ symptom score−0.96 (−1.10 to −0.83)−1.02 (−1.16 to −0.88)−1.09 (−1.23 to −0.96).41389
Change in ZCQ physical function score−0.79 (−0.89 to −0.69)−0.85 (−0.95 to −0.74)−0.91 (−1.01 to −0.80).30390
Change in NRS leg pain score−3.29 (−3.77 to −2.82)−3.61 (−4.10 to −3.13)−3.62 (−4.10 to −3.15).55377
Change in NRS low back pain score−2.59 (−3.05 to −2.13)−2.42 (−2.89 to −1.94)−2.96 (−3.43 to −2.50).25380
Global perceived effect score after 24 mo2.55 (2.32 to 2.78)2.55 (2.31 to 2.79)2.29 (2.06 to 2.52).21398
Duration of procedure, min95.7 (81.1 to 110.3)123.9 (109.0 to 138.7)92.9 (78.2 to 107.7)<.001416
Length of hospital stay, d2.84 (2.18 to 3.50)3.17 (2.51 to 3.84)3.09 (2.43 to 3.75).38363
Blood loss, mL139.0 (96.9 to 181.1)173.1 (130.8 to 215.4)150.7 (107.7 to 193.6).15373
Proportion reoperated, %7.9 (2.2 to 13.7)4.6 (4.3 to 8.8)8.2 (2.2 to 14.2).44416
Proportion incidental dural tear, %5.8 (1.6 to 10.0)7.5 (2.6 to 12.5)7.8 (2.9 to 12.6).79402
Proportion wound infection, %0 (NA)0.8 (0 to 2.3)0.0 (NA).32396
Proportion hematoma requiring reoperation, %1.0 (0 to 3.4)1.0 (0 to 3.5)1.9 (0 to 5.8).81397
Proportion other complications, %b1.5 (0 to 3.5)5.5 (1.4 to 9.5)4.5 (0.9 to 8.1).18397
Proportion neurological deterioration, %2.2 (0 to 4.8)1.6 (0 to 3.8)0.7 (0 to 2.2).59395

Abbreviations: EQ-5D, EuroQuol 5-dimension questionnaire utility index; NRS, numeric rating score; ODI, Oswestry Disability Index; ZCQ, Zurich Claudication Questionnaire.

a Means and corresponding 95% CI calculated by estimating marginal effects after fitting multilevel linear models with random intercepts for operating hospital and adjusting for baseline measure when analyzing change scores. Proportions and corresponding 95% CI calculated by estimating marginal effects after fitting multilevel Poisson models with random intercepts for operating hospital.

b Other complications include cardiovascular, venous thromboembolism, urological, and respiratory complications.

Figure 3.. Oswestry Disability Index After 3 Posterior Decompression Techniques for Lumbar Spinal Stenosis Given as Mean Score and Proportion of Patients Classified as Success
Figure 3.. Oswestry Disability Index After 3 Posterior Decompression Techniques for Lumbar Spinal Stenosis Given as Mean Score and Proportion of Patients Classified as Success Patients classified as successs had a reduction in baseline scores 30% or more. BL indicates bilateral laminotomy; SPO, spinous process osteotomy; UL, unilateral laminotomy with crossover.

Secondary Outcome

There were no statistically significant differences in change score for the secondary outcomes between the 3 surgical groups. Results from analyses on secondary outcomes are given in Table 2 and eFigure 1 and eTable 3 in Supplement 2. In the whole cohort, there was a mean improvement in EQ-5D of 0.32 (95% CI, 0.28-0.36). The mean change in ZCQ was 1.02 (95% CI, 0.94-1.11) for symptom severity and 0.85 (95% CI, 0.78-0.92) for physical function. Likewise, the mean improvement from baseline in NRS was 3.5 (95% CI, 3.2-3.8) for leg pain and 2.7 (95% CI, 2.4-3.0) for back pain.

The BL group had a longer mean duration of the surgical procedure, 123.9 (109.0-138.7) minutes compared with 95.7 (81.1-110.3) minutes and 92.9 (78.2-107.7) minutes for UL and SPO, respectively, (P < .001). For other relevant outcomes, there were no differences between the 3 surgical methods. All results related to the surgical procedures are given in Table 2. The mean duration of the surgical procedure was 101 (95% CI, 96-108) minutes for the total cohort, and the length of hospital stay was 3.1 (95% CI, 2.9-3.4) days. The total rate of reoperations in the whole cohort during the 2-year follow up period were 6.4% (95% CI, 4.3%-9.1%), the number of reoperations was 11 of 146 (7.5%) in the UL group, 6 of 142 (4.2%) in the BL group, and 11 of 149 (7.4%) in the SPO group. Overview of the reoperations during the hospital stay, until 3 months follow up, and finally until 2 years of follow up (eTable 4 to eTable 6 in Supplement 2).

Discussion

The results of this study found no association in favor of any of the 3 most commonly used minimally invasive decompression techniques for LSS in terms of effectiveness. We found no clinically relevant or statistically significant association in mean improvement regarding pain and disability or the proportion of patients reporting clinically important changes for the 3 treatment groups after 2 years (eFigure 2 and eFigure 3 in the Supplement). We also found no association that suggested effectiveness varied by level of the surgical procedure or number of levels operated. The results of the secondary patient-reported outcomes were in line with the primary outcome. We found no significant differences in outcomes related to the surgical procedure, such as length of hospital stay, perioperative blood loss, and perioperative complications. The SPO and UL procedures required approximately 30 minutes less than BL. These findings correspond with those of previous trials with smaller numbers of patients,11,12,13,14,15,16,17 both regarding improvement of patient-reported outcome measures and complication rates.

The main strength of the current study is the randomized design and high number of patients (eFigure 4 in the Supplement). Furthermore, the high rate of follow-up improves the internal validity. The external validity would be robust because of the pragmatic inclusion criteria and a large number of highly specialized and smaller orthopedic and neurosurgical centers from all over the country, participating in the inclusion and treatment of the patients. The baseline characteristics and the improvement in disability at 12 months were similar to a previous prospective cohort study from the Norwegian Registry for Spine Surgery,13 further indicating a strong external validity. Other strengths are the public financing of the study, blinding of the person who performed the statistical analyses, and the use of an independent study monitor according to ICH-GCP.

There was no statistical difference between the 3 groups regarding the proportion of reoperations during the primary hospital stay, after 3 months, or after 2 years. A 2-year follow-up period is probably insufficient for a complete evaluation or conclusion to be drawn. The study group plans to follow this cohort for 10 years to evaluate this topic more thoroughly. The number of reoperations will also reflect the durability of the various procedures, an important aspect of the effectiveness evaluation.

Limitations

This study has limitations. The minimally invasive surgical methods evaluated in this study are not compared with a full laminectomy. All the midline retaining procedures could potentially be important to avoid postlaminectomy spondylolisthesis.9,35,36 The reason for not including the laminectomy method was that most of the centers already had stopped using this technique and used the 3 minimally invasive techniques as standard methods. Moreover, a study from the Norwegian Registry for Spine Surgery has shown similar results after minimally invasive decompression and full laminectomy.10

A decompressive procedure is performed to relieve the dural compression at the affected level of the spine and be comprehensive enough to achieve sufficient symptom relief. A secondary radiological study from this trial reported that UL, BL, and SPO provided a similar increase of the dural sac cross-sectional area (DSCA).37 Hence, both radiological and clinical outcomes seem similar in the surgical techniques compared 2 years postoperatively. The outcome for these patients will be followed up with for 10 years to investigate eventual changes over time.

Mannion et al38 reported that a high degree of stenosis preoperatively was associated with a better outcome after the surgical procedure. However, it is unclear how extensive the increase of DSCA needs to be to obtain long-term symptom relief. One study has shown an association between a large increase of DSCA postoperatively and patient-reported outcome,39 but 2 studies did not confirm these findings.14,40 In our opinion, it has not been established whether a wide decompression yields superior clinical results compared with less extensive decompression. The threshold value for the decompression size will be addressed in a future study. In our opinion, it is important to differentiate the effect of the surgical procedure and to evaluate the impact of the decompression method used in terms of the effect on the surrounding structures, including stability of the spine and muscular damage. This will also be addressed in further studies from the NORDSTEN-SST cohort.

The 3 different surgical techniques vary in how much the surrounding tissue is affected. BL requires a bilateral release of the multifidus muscle, and SPO requires an osteotomy of the spinous process. The degree of surgical trauma can affect postoperative fibrosis of the muscles and nerve innervation. The equivalent clinical result from the present study indicates that the surgical impact of the surrounding tissue is of minor importance and that other factors concerning the surgical outcome must be assessed to improve the results after the surgical procedure for LSS.

The change in inclusion criteria, including patients with a baseline ODI of fewer than 25 points, might be seen as a limitation. To investigate the robustness of our findings, we performed analyses studying the effect of surgical technique by timing of study inclusion (before or after November 1, 2015). No evidence suggesting differential effects by inclusion period were found (eTable 7 in Supplement 2).

The actual sample size was somewhat lower than initially planned, which would reduce the statistical power of the study. Originally, we planned our study with a 15% drop-out, corresponding to an actual sample size of 135 participants per study arm. However, the drop-out rate turned out to be lower so the number of participants eligible for analyzing the primary outcome was 393, corresponding to a sample size of 131 per arm. With the same a priori assumptions, this sample size would give an estimated power of 79%, only marginally lower than the required 80%.

Conclusions

In the present trial of patients treated surgically for lumbar spinal stenosis, there were no differences in the effectiveness between the 3 most commonly used minimally invasive posterior decompression techniques. The complication rates did not differ among the 3 methods, although surgical time differed among them.

Declarations

Supplement 1.: eAppendix 1. The NORDSTEN-Study Spinal Stenosis Trial-SST Protocol — available with the version of record.

Supplement 2.: eTable 1. Inclusion and Exclusion Criteria for the Spinal Stenosis Trial (SST) in the NORDSTEN-Study — available with the version of record.

Supplement 3.: Data Sharing Statement — available with the version of record.

Sources

References

40 references, in the article's own order. Citation numbers in the text are this list's numbers (40 records are cited).

  1. Degenerative lumbar spinal stenosis: an evidence-based clinical guideline for the diagnosis and treatment of degenerative lumbar spinal stenosis

    Watters WC, Baisden J, Gilbert TJ, et al.

    2008Spine J 8(2):305–310 · PMID 18082461doi:10.1016/j.spinee.2007.10.033

  2. Lumbar spinal stenosis: conservative or surgical management: a prospective 10-year study

    Amundsen T, Weber H, Nordal HJ, Magnaes B, Abdelnoor M, Lilleas F

    2000Spine (Phila Pa 1976) 25(11):1424–1435 · PMID 10828926doi:10.1097/00007632-200006010-00016

  3. Surgical or nonoperative treatment for lumbar spinal stenosis: a randomized controlled trial

    Malmivaara A, Slatis P, Heliovaara M, et al.

    2007Spine (Phila Pa 1976) 32(1):1–8 · PMID 17202885doi:10.1097/01.brs.0000251014.81875.6d

  4. Surgical versus nonoperative treatment for lumbar spinal stenosis four-year results of the Spine Patient Outcomes Research Trial

    Weinstein JN, Tosteson TD, Lurie JD, et al.

    2010Spine (Phila Pa 1976) 35(14):1329–1338 · PMID 20453723doi:10.1097/BRS.0b013e3181e0f04d

  5. Surgical versus nonsurgical treatment for lumbar spinal stenosis

    Zaina F, Tomkins-Lane C, Carragee E, Negrini S

    2016Spine (Phila Pa 1976) 41(14):E857–E868 · PMID 27128388doi:10.1097/BRS.0000000000001635

  6. Trends, major medical complications, and charges associated with surgery for lumbar spinal stenosis in older adults

    Deyo RA, Mirza SK, Martin BI, Kreuter W, Goodman DC, Jarvik JG

    2010JAMA 303(13):1259–1265 · PMID 20371784doi:10.1001/jama.2010.338

  7. Lumbar spine surgery across 15 years: trends, complications and reoperations in a longitudinal observational study from Norway

    Grotle M, Småstuen MC, Fjeld O, et al.

    2019BMJ Open 9(8):e028743 · PMID 31375617doi:10.1136/bmjopen-2018-028743

  8. Effectiveness of posterior decompression techniques compared with conventional laminectomy for lumbar stenosis

    Overdevest GM, Jacobs W, Vleggeert-Lankamp C, Thome C, Gunzburg R, Peul W

    2015Cochrane Database Syst Rev 3:CD010036 · PMID 25760812doi:10.1002/14651858.CD010036.pub2

  9. Iatrogenic spondylolisthesis following laminectomy for degenerative lumbar stenosis: systematic review and current concepts

    Guha D, Heary RF, Shamji MF

    2015Neurosurg Focus 39(4):E9 · PMID 26424349doi:10.3171/2015.7.FOCUS15259

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

    Nerland US, Jakola AS, Solheim O, et al.

    2015BMJ 350:h1603 · PMID 25833966doi:10.1136/bmj.h1603

  11. Comparison of unilateral hemilaminotomy and bilateral hemilaminotomy according to dural sac area in lumbar spinal stenosis

    Dalgic A, Uckun O, Ergungor MF, et al.

    2010Minim Invasive Neurosurg 53(2):60–64 · PMID 20549602doi:10.1055/s-0029-1246147

  12. Long-term outcomes of two different decompressive techniques for lumbar spinal stenosis

    Fu YS, Zeng BF, Xu JG

    2008Spine (Phila Pa 1976) 33(5):514–518 · PMID 18317196doi:10.1097/BRS.0b013e3181657dde

  13. Does surgical technique influence clinical outcome after lumbar spinal stenosis decompression: a comparative effectiveness study from the Norwegian Registry for Spine Surgery

    Hermansen E, Romild UK, Austevoll IM, et al.

    2017Eur Spine J 26:420–427 · PMID 27262561doi:10.1007/s00586-016-4643-9

  14. A comparison of unilateral and bilateral laminotomies for decompression of L4-L5 spinal stenosis

    Hong SW, Choi KY, Ahn Y, et al.

    2011Spine (Phila Pa 1976) 36(3):E172–E178 · PMID 21192307doi:10.1097/BRS.0b013e3181db998c

  15. Patient outcomes after laminotomy, hemilaminectomy, laminectomy and laminectomy with instrumented fusion for spinal canal stenosis: a propensity score-based study from the Spine Tango registry

    Munting E, Roder C, Sobottke R, Dietrich D, Aghayev E

    2014EurSpine J 24:358–368 · PMID 24840246doi:10.1007/s00586-014-3349-0

  16. The surgical treatment of central lumbar stenosis: multiple laminotomy compared with total laminectomy

    Postacchini F, Cinotti G, Perugia D, Gumina S

    1993J Bone Joint Surg Br 75(3):386–392 · PMID 8496205doi:10.1302/0301-620X.75B3.8496205

  17. Outcome after less-invasive decompression of lumbar spinal stenosis: a randomized comparison of unilateral laminotomy, bilateral laminotomy, and laminectomy

    Thome C, Zevgaridis D, Leheta O, et al.

    2005J Neurosurg Spine 3(2):129–141 · PMID 16370302doi:10.3171/spi.2005.3.2.0129

  18. Surgical options for lumbar spinal stenosis

    Machado GC, Ferreira PH, Yoo RI, et al.

    2016Cochrane Database Syst Rev 11(11):CD012421 · PMID 27801521doi:10.1002/14651858.CD012421

  19. The evidence on surgical interventions for low back disorders, an overview of systematic reviews

    Jacobs WC, Rubinstein SM, Willems PC, et al.

    2013Eur Spine J 22(9):1936–1949 · PMID 23681497doi:10.1007/s00586-013-2823-4

  20. Study-protocol for a randomized controlled trial comparing clinical and radiological results after three different posterior decompression techniques for lumbar spinal stenosis: the Spinal Stenosis Trial (SST) (part of the NORDSTEN Study)

    Hermansen E, Austevoll IM, Romild UK, et al.

    2017BMC Musculoskelet Disord 18(1):121 · PMID 28327114doi:10.1186/s12891-017-1491-7

  21. CONSORT for reporting randomized controlled trials in journal and conference abstracts: explanation and elaboration

    Hopewell S, Clarke M, Moher D, et al.

    2008PLoSMed 5(1):e20 · PMID 18215107doi:10.1371/journal.pmed.0050020

  22. International conference on harmonisation of technical requirements for registration of pharmaceuticals for human use

    Singh J

    2015J Pharmacol Pharmacother 6(3):185–187 · PMID 26312010doi:10.4103/0976-500X.162004

  23. Unilateral laminectomy for bilateral decompression of lumbar spinal stenosis: a prospective comparative study with conservatively treated patients

    Mariconda M, Fava R, Gatto A, Longo C, Milano C

    2002J Spinal Disord Tech 15(1):39–46 · PMID 11891449doi:10.1097/00024720-200202000-00006

  24. Multilevel lumbar laminotomies: an alternative to laminectomy in the treatment of lumbar stenosis

    Aryanpur J, Ducker T.

    1990Neurosurgery 26(3):429–432 · PMID 2138716doi:10.1227/00006123-198807000-00021

  25. Osteotomy of lumbar spinous process to increase surgical exposure

    Yong-Hing K, Kirkaldy-Willis WH

    1978Clin Orthop Relat Res 218–220 · PMID 729248

  26. The oswestry disability index

    Fairbank JC, Pynsent PB

    2000Spine (Phila Pa 1976) 25(22):2940–2952 · PMID 11074683doi:10.1097/00007632-200011150-00017

  27. Functional status and disability questionnaires: what do they assess: a systematic review of back-specific outcome questionnaires

    Grotle M, Brox JI, Vøllestad NK

    2005Spine (Phila Pa 1976) 30(1):130–140 · PMID 15626993doi:10.1097/01.brs.0000149184.16509.73

  28. Follow-up score, change score or percentage change score for determining clinical important outcome following surgery: an observational study from the Norwegian registry for spine surgery evaluating patient reported outcome measures in lumbar spinal stenosis and lumbar degenerative spondylolisthesis

    Austevoll IM, Gjestad R, Grotle M, et al.

    2019BMC Musculoskelet Disord 20(1):31 · PMID 30658613doi:10.1186/s12891-018-2386-y

  29. The value of patient global assessment in lumbar spine surgery: an evaluation based on more than 90,000 patients

    Parai C, Hägg O, Lind B, Brisby H

    2018Eur Spine J 27(3):554–563 · PMID 29058135doi:10.1007/s00586-017-5331-0

  30. Health-related quality of life assessment by the EuroQol-5D can provide cost-utility data in the field of low-back surgery

    Solberg TK, Olsen JA, Ingebrigtsen T, Hofoss D, Nygaard OP

    2005Eur Spine J 14(10):1000–1007 · PMID 15843969doi:10.1007/s00586-005-0898-2

  31. Measurement properties of a self-administered outcome measure in lumbar spinal stenosis

    Stucki G, Daltroy L, Liang MH, Lipson SJ, Fossel AH, Katz JN

    1996Spine (Phila Pa 1976) 21(7):796–803 · PMID 8779009doi:10.1097/00007632-199604010-00004

  32. Validity of four pain intensity rating scales

    Ferreira-Valente MA, Pais-Ribeiro JL, Jensen MP

    2011Pain 152(10):2399–2404 · PMID 21856077doi:10.1016/j.pain.2011.07.005

  33. Interpreting the clinical importance of treatment outcomes in chronic pain clinical trials: IMMPACT recommendations

    Dworkin RH, Turk DC, Wyrwich KW, et al.

    2008J Pain 9(2):105–121 · PMID 18055266doi:10.1016/j.jpain.2007.09.005

  34. The CONSORT statement

    Cuschieri S

    2019Saudi J Anaesth 13(suppl 1):S27–S30 · PMID 30930716doi:10.4103/sja.SJA_559_18

  35. Postdecompression lumbar instability

    Hopp E, Tsou PM

    1988Clin Orthop Relat Res 227(227):143–151 · PMID 2962798

  36. Postoperative lumbar spinal instability occurring or progressing secondary to laminectomy

    Iida Y, Kataoka O, Sho T, et al.

    1990Spine (Phila Pa 1976) 15(11):1186–1189 · PMID 2148439doi:10.1097/00007632-199011010-00018

  37. Comparable increases in dural sac area after three different posterior decompression techniques for lumbar spinal stenosis: radiological results from a randomized controlled trial in the NORDSTEN study

    Hermansen E, Austevoll IM, Hellum C, et al.

    2020Eur Spine J 29(9):2254–2261 · PMID 32556585doi:10.1007/s00586-020-06499-0

  38. Dural sac cross-sectional area and morphological grade show significant associations with patient-rated outcome of surgery for lumbar central spinal stenosis

    Mannion AF, Fekete TF, Pacifico D, et al.

    2017Eur Spine J 26(10):2552–2564 · PMID 28856447doi:10.1007/s00586-017-5280-7

  39. Laminarthrectomy as a surgical approach for decompressing the spinal canal: assessment of preoperative versus postoperative dural sac cross-sectional areal (DSCSA)

    Hermansen E, Moen G, Barstad J, Birketvedt R, Indrekvam K

    2013Eur Spine J 22(8):1913–1919 · PMID 23494757doi:10.1007/s00586-013-2737-1

  40. Postoperative expansion of dural sac cross-sectional area after unilateral laminotomy for bilateral decompression: correlation with clinical symptoms

    Chung SW, Kang MS, Shin YH, Baek OK, Lee SH

    2014Korean J Spine 11(4):227–231 · PMID 25620982doi:10.14245/kjs.2014.11.4.227

Article record

The record

Status

Living reprint · journal article Journal version available

Status
Version of record: JAMA Network Open 2022
Journal version
JAMA Network Open (2022) · doi:10.1001/jamanetworkopen.2022.4291
Confirmed
2022-03-28
Licence
CC BY 4.0

This reprint has no DOI of its own: cite the journal article.

The journal's version is the version of record. This page re-typesets it under the article's licence; where they differ, the journal's version is authoritative.

Version history

  1. Published in JAMA Network Open2022-03-28
  2. Living reprint on Literature Decoded2026-10-01
  3. Reprinted here2026-10-01
  4. This HTML2026-10-01

Cite this article

Citation
Hermansen E, Austevoll IM, Hellum C, Storheim K, Myklebust TÅ, Aaen J, et al. Comparison of 3 Different Minimally Invasive Surgical Techniques for Lumbar Spinal Stenosis: A Randomized Clinical Trial. JAMA Netw Open. 2022;5(3):e224291. doi:10.1001/jamanetworkopen.2022.4291
BibTeX
@article{Hermansen2022Comparison,
  title   = {Comparison of 3 Different Minimally Invasive Surgical Techniques for Lumbar Spinal Stenosis: A Randomized Clinical Trial},
  author  = {Erland Hermansen and Ivar Magne Austevoll and Christian Hellum and Kjersti Storheim and Tor Åge Myklebust and Jørn Aaen and Hasan Banitalebi and Masoud Anvar and Frode Rekeland and Jens Ivar Brox and Eric Franssen and Clemens Weber and Tore K. Solberg and Håvard Furunes and Oliver Grundnes and Helena Brisby and Kari Indrekvam},
  journal = {JAMA Network Open},
  year    = {2022},
  volume  = {5},
  number  = {3},
  pages   = {e224291},
  doi     = {10.1001/jamanetworkopen.2022.4291},
  pmid    = {35344046}
}
RIS
TY  - JOUR
TI  - Comparison of 3 Different Minimally Invasive Surgical Techniques for Lumbar Spinal Stenosis: A Randomized Clinical Trial
AU  - Erland Hermansen
AU  - Ivar Magne Austevoll
AU  - Christian Hellum
AU  - Kjersti Storheim
AU  - Tor Åge Myklebust
AU  - Jørn Aaen
AU  - Hasan Banitalebi
AU  - Masoud Anvar
AU  - Frode Rekeland
AU  - Jens Ivar Brox
AU  - Eric Franssen
AU  - Clemens Weber
AU  - Tore K. Solberg
AU  - Håvard Furunes
AU  - Oliver Grundnes
AU  - Helena Brisby
AU  - Kari Indrekvam
JO  - JAMA Network Open
PY  - 2022
VL  - 5
IS  - 3
SP  - e224291
DO  - 10.1001/jamanetworkopen.2022.4291
SN  - 2574-3805
UR  - https://doi.org/10.1001/jamanetworkopen.2022.4291
ER  -

Cite the original article (the version of record), not this reprint.

Take it with you

One self-contained HTML file: the text, data and figures, readable offline.

Disclaimer and limitations

Educational summary of research findings; not medical advice. Discuss care decisions with a qualified clinician.

The findings apply to the included study populations and may not generalise to every person or setting.

Licence and attribution

This page reproduces Comparison of 3 Different Minimally Invasive Surgical Techniques for Lumbar Spinal Stenosis: A Randomized Clinical Trial by Erland Hermansen, Ivar Magne Austevoll, Christian Hellum, Kjersti Storheim, Tor Åge Myklebust, Jørn Aaen, Hasan Banitalebi, Masoud Anvar, Frode Rekeland, Jens Ivar Brox, Eric Franssen, Clemens Weber, Tore K. Solberg, Håvard Furunes, Oliver Grundnes, Helena Brisby, Kari Indrekvam, first published in JAMA Network Open 2022;5(3):e224291, doi:10.1001/jamanetworkopen.2022.4291, PMID 35344046, PMC8961320. Copyright 2022 Hermansen E et al. JAMA Network Open. It is used under the CC BY 4.0 licence.

Changes made:

The words, data, figures and conclusions are the authors’. Literature Decoded is not the publisher of record and does not claim endorsement by the authors or the journal. The version of record is the journal’s; cite it.

Licence statement in the article: “This is an open access article distributed under the terms of the CC-BY License.”

Are you an author of this article? Claim it or ask us to take it down.

Cite this article

Living reprint · journal article