Christian Hellum

• Hansen, Vinjar Brenna; Schulz, Anselm; Hellum, Christian & Röhrl, Stephan Maximilian Herbert (2026). Movement of the sacroiliac joint during a modified active straight leg raise measured with CT-RSA: a feasibility study. Acta Orthopaedica. ISSN 1745-3674. 97, p. 151–155. doi: 10.2340/17453674.2026.45479. Full text in Research Archive
• Hermansen, Erland; Brisby, Helena; Bolminger, Hanna Hebelka; Myklebust, Tor Åge; Indrekvam, Kari & Hellum, Christian [Show all 10 contributors for this article] (2026). Agreement of CT versus MRI in reinvestigation of patients operated for lumbar spinal stenosis. a comparison of surgically and non-surgically treated levels. European spine journal. ISSN 0940-6719. doi: 10.1007/s00586-026-09873-6. Full text in Research Archive Show summary

  Purpose Surgical decision-making for lumbar spinal stenosis (LSS) depends on accurate imaging. MRI is preferred, but contraindications may require CT. This study compared CT‑ and MRI-based measurements of dural sac cross-sectional area (DSCA) at operated and non-operated levels two years after LSS surgery. Materials and methods Patients from the NORDSTEN Spinal Stenosis Trial (SST) were evaluated. Patients randomized to spinous process osteotomy (SPO) underwent both CT and MRI at two-year follow-up. Two independent readers measured DSCA on axial MRI at L2–L5. On CT, the inner ligamentous canal boundary was delineated to approximate the DSCA. Mean values were compared using Student’s t‑test, and interobserver reliability assessed with intraclass correlation coefficients (ICCs). Results Of 149 eligible patients, 96 (64%) completed both imaging modalities. Mean age was 65.9 years, and 66% were male. In total, 274 lumbar levels were analysed, including 123 surgically treated levels. CT produced slightly larger canal areas than MRI: +2 to + 4 mm² at non-operated levels and + 11 to + 14 mm² at operated levels (p < 0.05). Interobserver agreement was good for CT and comparable to MRI (ICC 0.80–0.96). Conclusions CT and MRI provided broadly comparable measurements of the spinal canal, with small systematic differences. The modestly larger CT areas at surgically treated levels are likely of limited clinical relevance, though their importance in patients with very small canals remains uncertain. CT may serve as a supplementary postoperative modality, but further research is needed before it can be considered a consistent alternative to MRI.

• Nomeland, Aline Andersen; Brekke, Erik Andreas Mosvold; Seip, Andreas Ottersen; Myklebust, Tor Åge; Ebbs, Eira Kathleen & Solberg, Tore [Show all 18 contributors for this article] (2026). Predictors for Unsuccessful Outcome of Lumbar Spinal Stenosis Surgery : A Secondary Analysis of the 2 Randomized NORDSTEN Trials. Spine. ISSN 0362-2436. 51(8), p. 527–533. doi: 10.1097/BRS.0000000000005642. Full text in Research Archive Show summary

  Study Design: Observational cohort study. Objective: To evaluate potential predictors of unsuccessful outcomes after surgery in patients with lumbar spinal stenosis (LSS). Summary of Background Data: LSS is a common cause of disability in adults and the leading indication for spine surgery in Norway. Despite advances in surgical techniques, nearly one-third of patients report either minor or no improvement or worsening of symptoms after surgery. Identifying predictors of unsuccessful outcomes is essential for improving patient selection and shared decision-making. Materials and Methods: This secondary analysis used data from the 2 NORwegian Degenerative spondylolisthesis and spinal STENosis (NORDSTEN) randomized trials, which included 704 surgically treated patients with LSS, with (n=267) or without (n=437) degenerative spondylolisthesis. The Oswestry Disability Index (ODI) was the primary outcome measure. A reduction in ODI score of <30% from baseline to 2 years postoperatively was defined as an unsuccessful outcome. Multivariable logistic regression analysis was used to evaluate whether carefully selected baseline variables were associated with an unsuccessful outcome at 2-year follow-up. Results: Longer duration of radiating pain (>12 mo; OR: 2.58, 95% CI: 1.54–4.29), psychological distress (HSCL-25 ≥1.75; OR: 1.60, 95% CI: 1.01–2.53), and advanced disc degeneration (Pfirrmann grades 4–5; OR: 1.98, 95% CI: 1.26–3.12) were independently associated with an unsuccessful outcome. Commonly discussed factors such as age, BMI, smoking, ASA grade, and predominant back pain did not reach statistical significance for association with the outcome. Conclusion: Among patients undergoing surgery for LSS, longer symptom duration, psychological distress, and advanced disc degeneration were associated with a higher risk of unsuccessful postoperative outcomes.

• Seip, Andreas Ottersen; Hellum, Christian; Fagerland, Morten; Solberg, Tore; Brox, Jens Ivar & Storheim, Kjersti [Show all 14 contributors for this article] (2025). Surgeon Recommendation and Outcomes of Decompression With vs Without Fusion in Patients With Degenerative Spondylolisthesis. JAMA Network Open. 8(1), p. 1–13. doi: 10.1001/jamanetworkopen.2024.53466. Full text in Research Archive Show summary

  Importance: The ability of surgeons to choose the right patient for fusion in addition to decompression when operating for degenerative spondylolisthesis with symptomatic spinal stenosis is debated. The addition of fusion increases risk, morbidity, and costs but has been claimed to give better results for selected patients. Objective: To investigate whether following surgeons’ opinions regarding fusion was associated with clinical outcomes. Design, Setting, and Participants: This cohort study was conducted alongside the Norwegian Degenerative Spondylolisthesis and Spinal Stenosis randomized clinical trial, which showed noninferiority for decompression alone compared with decompression with fusion. From February 12, 2014, to December 18, 2017, trial surgeons from 16 Norwegian departments denoted their preferred treatment for 222 of 267 patients with symptomatic spinal stenosis and degenerative spondylolisthesis. For this analysis, the clinical outcomes of the patients who were and were not randomized to the recommended treatment were compared. Main Outcome and Measures: The primary outcome was a reduction of at least 30% from baseline to 2 years after surgery on the Oswestry Disability Index, ranging from 0 (no impairment) to 100 (maximum impairment). Secondary outcomes included the Zürich Claudication Questionnaire, leg and back pain scores, and the EuroQol 5-Dimension score. Results: Among 222 patients (155 [70%] female; mean [SD] age, 66.2 [7.7] years), decompression alone was recommended for 112 patients, of whom 59 received only decompression, and additional fusion for 110 patients, of whom 57 received fusion. At 2-year follow-up, 87 of 116 patients (75%) who received surgery in agreement with the surgeons’ recommendations and 77 of 106 (73%) who received surgery in disagreement with the surgeons’ recommendations reached the primary outcome (difference, 2.4 percentage points; 95% CI, −9.1 to 13.9 percentage points). All secondary outcomes were in the same direction as the primary outcome. Conclusions and Relevance: In this cohort study of 222 patients with degenerative spondylolisthesis who participated in a randomized clinical trial, surgeons’ recommendations were not associated with better outcomes than a random allocation when deciding between decompression alone and decompression with instrumented fusion. The results suggest that surgeons performing degenerative spondylolisthesis surgery could rely safely on evidence of operating with decompression alone, despite the conflict of expert opinion.

• Hermansen, Erland; Franssen, Eric; Myklebust, Tor Åge; Indrekvam, Kari; Austevoll, Ivar Magne & Hellum, Christian [Show all 14 contributors for this article] (2025). No long term benefit of decompression of a borderline lumbar spinal stenosis level adjacent to a more stenotic index level. European spine journal. ISSN 0940-6719. 34, p. 5715–5724. doi: 10.1007/s00586-025-09113-3. Full text in Research Archive Show summary

  Purpose: Lumbar spinal stenosis (LSS) frequently involves multiple levels of the spine. Whether to perform single-level decompression (SLD) or multi-level decompression (MLD) in patients with at least one borderline stenotic level adjacent to the primary (index) level, remains debated. Short-term follow-up studies show comparable outcomes for both strategies. This study aimed to assess five-year outcomes in patients with adjacent borderline stenosis. Material: All participants were recruited from the NORDSTEN-SST. Patients with a preoperative adjacent borderline stenosis, defined as Schizas grade B or C, in addition to the index level, were included in the study. The cohort was divided into two groups based on the type of surgical intervention: SLD or MLD. Baseline characteristics and clinical outcomes were recorded for both groups, with follow-up conducted five years postoperatively. Subgroup analysis based on the Schizas grade in the adjacent level were also performed. Results: Out of 437 patients in the NORDSTEN-SST, the 222 with borderline adjacent stenosis were included. Among these, 114 underwent SLD, while 108 underwent MLD. Baseline characteristics were comparable between groups. Mean change in ODI-score was − 16.0 (95% CI -18.9—12.9) for the SLD group and − 18.6 (95% CI -22.1—15.1) for the MLD group, p = 0.26. Subgroup analyses revealed no significant differences between groups in clinical outcomes or need for subsequent spinal surgeries. Conclusion: In this observational study, five-year clinical outcomes in patients operated for lumbar spinal stenosis with a significant stenotic index level were not influenced by additional decompression of preoperative adjacent borderline stenotic levels.

• Brisby, Helena; Myklebust, Tor Åge; BANITALEBI, HASAN; Austevoll, Ivar Magne; Aaen, Jorn & Storheim, Kjersti [Show all 10 contributors for this article] (2024). Adjacent Level Canal Area Changes up to Two Years After Lumbar Spinal Stenosis Decompressive Surgery. Spine. ISSN 0362-2436. 50(7), p. 436–436. doi: 10.1097/brs.0000000000005247. Full text in Research Archive Show summary

  Study Design. A secondary analysis of data from the NORDSTEN-spinal stenosis trial (SST) Objective. 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. Summary of Background Data. Decompressive surgery for LSS is currently the most common spinal surgery procedure; however, there is limited knowledge of changes in the DSCA over time adjacent to a decompressed segment. Materials and Methods. In the NORDSTEN-SST, 437 patients were randomized to decompression with one of three minimally invasive surgical methods for LSS. The patients underwent an 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, radiologic measures, and surgical method) for changes in the adjacent DSCA were examined using multivariate regression analyses. Results. Three hundred twenty-two 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 two years postoperatively, no decrease in adjacent DSCA was observed. No associations were found between the investigated baseline variables and DSCA change from zero to two years, except for a weak association with baseline adjacent DSCA. Conclusions. Up to two years postoperatively, the DSCA did not decrease at adjacent levels after decompressive surgery. None of the investigated baseline variables showed any clinically meaningful prognostic value regarding adjacent DSCA changes two years postoperatively. The findings support previous reports that decompression of adjacent levels is not required to prevent subsequent stenosis.

• Tronstad, Sara; Haug, Knut Jørgen; Myklebust, Tor Åge; Weber, Clemens; Brisby, Helena & Austevoll, Ivar Magne [Show all 16 contributors for this article] (2024). Do patients with lumbar spinal stenosis benefit from decompression of levels with adjacent moderate stenosis? A prospective cohort study from the NORDSTEN study. The spine journal. ISSN 1529-9430. 24(6), p. 1015–1021. doi: 10.1016/j.spinee.2024.01.010. Full text in Research Archive Show summary

  Background: Lumbar spinal stenosis (LSS) is characterized by pain that radiates to the buttocks and/or legs, aggravated by walking and relieved by forward flexion. There is poor correlation between clinical symptoms and severity of stenosis on MRI, and multilevel stenosis has not been described to present worse symptoms or treatment outcomes, compared with patients with single-level stenosis. In patients with one level with severe stenosis combined with an adjacent level with moderate stenosis, the surgeon must decide whether to decompress only the narrowest level or both, to achieve the best possible outcome. The potential benefits of performing surgery on an adjacent moderate stenosis is debated, and the scientific evidence in scarce. Purpose: The aim of the present study was to investigate whether patients with a level of adjacent moderate stenosis, along with an index stenosis, benefitted from a dual-level decompression (DLD) compared with a single-level decompression (SLD). Furthermore, to investigate whether DLD patients had longer duration of surgery and hospital stay, higher rates of complications and/or lower rate of reoperations compared with SLD patients. Study design: Prospective cohort study. Patient sample: We analyzed data from the Norwegian Degenerative Spondylisthesis and Spinal Stenosis study- Spinal Stenosis Trial (NORDSTEN-SST). In this randomized multicenter study, 437 patients were included, evaluating clinical outcomes of three different surgical treatment options for LSS. Patients with degenerative spondylolisthesis were excluded. Method: Based on preoperative MRI, the present analysis included all patients who had a moderate stenosis (defined as Schizas B or C) in addition to a predefined index stenosis (the level with the smallest cross-sectional area). We compared patients who, based on the surgeons` choice, received a dual-level decompression, with those receiving a single-level decompression. Outcome measures: The primary outcome was mean change in the Oswestry Disability Index (ODI) score from baseline to 2-year follow up. Secondary outcomes were proportion of success (30% reduction in ODI score), the Numeric Rating Scales for back and leg pain (NRS), the EuroQol 5-dimensional questionnaire utility index (EQ-5D), the Zurich Claudication Questionnaire (ZCQ), the Global Perceived Effect (GPE)-scale, duration of surgery, duration of hospital stay, perioperative complications and reoperation rates. Results: Among the 222 patients, included in the analysis, 108 underwent DLD and 114 underwent SLD. There was no difference in change scores for any of the investigated patient-reported outcomes between the groups after 2 years. However, the DLD group had longer duration of surgery and longer length of hospital stay. There was no difference in reoperation rates or perioperative complications. Conclusion: This study, alongside the NORDSTEN-LSS trial on patients with adjacent moderate stenosis as well as an index stenosis, showed no superior clinical effectiveness for dual-level surgery compared with single-level surgery.

• Kgomotso, Eric Loratang; Hellum, Christian; Fagerland, Morten; Solberg, Tore; Brox, Jens Ivar & Storheim, Kjersti [Show all 16 contributors for this article] (2024). Decompression alone or with fusion for degenerative lumbar spondylolisthesis (Nordsten-DS): five year follow-up of a randomised, multicentre, non-inferiority trial. The BMJ. 386, p. 1–11. doi: 10.1136/bmj-2024-079771. Full text in Research Archive Show summary

  Objective: To assess whether decompression alone is non-inferior to decompression with instrumented fusion five years after primary surgery in patients with degenerative lumbar spondylolisthesis. Design: Five year follow-up of a randomised, multicentre, non-inferiority trial (Nordsten-DS). Setting: 16 public orthopaedic and neurosurgical clinics in Norway. Participants: Patients aged 18-80 years with symptomatic lumbar spinal stenosis and a spondylolisthesis of 3 mm or more at the stenotic level. Interventions: Decompression surgery alone and decompression with additional instrumented fusion (1:1). Main outcome measures: The primary outcome was a 30% or more reduction in Oswestry disability index from baseline to five year follow-up. The predefined non-inferiority margin was a -15 percentage point difference in the proportion of patients who met the primary outcome. Secondary outcomes included the mean change in Oswestry disability index, Zurich claudication questionnaire, numeric rating scale for leg and back pain, and EuroQol Group 5-Dimension (EQ-5D-3L) questionnaire. Results: From 12 February 2014 to 18 December 2017, 267 participants were randomly assigned to decompression alone (n=134) and decompression with instrumented fusion (n=133). Of these, 230 (88%) responded to the five year questionnaire: 121 in the decompression group and 109 in the fusion group. Mean age at baseline was 66.2 years (SD 7.6), and 69% were women. In the modified intention-to-treat analysis with multiple imputation of missing data, 84 (63%) of 133 people in the decompression alone group and 81 (63%) of 129 people in the fusion group had a at least a 30% reduction in Oswestry disability index, a difference of 0.4 percentage points. (95% confidence interval (CI) -11.2 to 11.9). The respective results of the per protocol analysis were 65 (65%) of 100 in the decompression alone group and 59 (66%) of 89 in the fusion group, a difference of -1.3 percentage points (95% CI -14.5 to 12.2). Both 95% CIs were higher than the predefined non-inferiority margin of -15%. The mean change in Oswestry disability index from baseline to five years was -17.8 in both groups (mean difference 0.02 (95% CI -3.8 to 3.9)). Results of the other secondary outcomes were in the same direction as the primary outcome. From two to five year follow-up, a new lumbar operation occurred in six (5%) of 123 people in the decompression group and 11 (10%) of 113 people in the fusion group, with a total from baseline to five years of 21 (16%) of 129 people and 23 (18%) of 125, respectively. Conclusions: In participants with degenerative spondylolisthesis, decompression alone was non-inferior to decompression with instrumented fusion five years after primary surgery. Proportions of subsequent surgeries at the index level or an adjacent lumbar level were no different between the groups. Trial registration: ClinicalTrials.gov NCT02051374.

• Wänman, Johan; Åkerstedt, Josefin; Banitalebi, Hasan; Myklebust, Tor Åge; Weber, Clemens & Storheim, Kjersti [Show all 11 contributors for this article] (2024). The association between lumbar lordosis preoperatively and changes in PROMs for lumbar spinal stenosis patients 2 years after spinal surgery: radiological and clinical results from the NORDSTEN-spinal stenosis trial. European spine journal. ISSN 0940-6719. 33, p. 1950–1956. doi: 10.1007/s00586-024-08137-5. Full text in Research Archive Show summary

  Background Patients with lumbar spinal stenosis (LSS) sometimes have lower lumbar lordosis (LL), and the incidence of LSS correlates closely with the loss of LL. The few studies that have evaluated the association between LL and clinical outcomes after non-instrumented surgery for LSS show conflicting results. This study investigates the association between preoperative LL and changes in PROMs 2 years after decompressive surgery. Method This prospective cohort study obtained preoperative and postoperative data for 401 patients from the multicenter randomized controlled spinal stenosis trial as part of the NORwegian degenerative spondylolisthesis and spinal STENosis (NORDSTEN) study. Before surgery, the radiological sagittal alignment parameter LL was measured using standing X-rays. The association between LL and 2-year postoperative changes was analyzed using the oswestry disability index (ODI), a numeric rating scale (NRS) for low back and leg pain, the Zurich claudication questionnaire (ZCQ), and the global perceived effect (GPE) score. The changes in PROMs 2 years after surgery for quintiles of lumbar lordosis were adjusted for the respective baseline PROMs: age, sex, smoking, and BMI. The Schizas index and the Pfirrmann index were used to analyze multiple regressions for changes in PROMs. Results There were no associations in the adjusted and unadjusted analyses between preoperative LL and changes in ODI, ZCQ, GPE, and NRS for back and leg pain 2 years after surgery. Conclusion LL before surgery was not associated with changes in PROMs 2 years after surgery. Lumbar lordosis should not be a factor when considering decompressive surgery for LSS.

• Hermansen, Erland; Indrekvam, Kari; Franssen, Eric; Myklebust, Tor Åge; Austevoll, Ivar Magne & Hellum, Christian [Show all 16 contributors for this article] (2024). A randomized trial on three different minimally invasive decompression techniques for lumbar spinal stenosis. Five years follow-up from the NORDSTEN-SST. European spine journal. ISSN 0940-6719. doi: 10.1007/s00586-024-08514-0. Full text in Research Archive Show summary

  Purpose: The short-term clinical outcome for midline-preserving posterior decompression techniques was comparable. The aim of this study was to evaluate long-term clinical results after three different midline-preserving posterior decompression techniques. Material: In the NORDSTEN spinal stenosis trial (NORDSTEN-SST) 437 patients were randomized to three different midline-retaining posterior decompression techniques: Unilateral laminotomy with crossover (UL), bilateral laminotomy (BL) and spinous process osteotomy (SPO). Primary outcome was the mean change in Oswestry disability index (ODI) score at five-years follow-up. Secondary outcomes were the proportion of patients classified as success, mean change in EQ-5D, ZCQ-score, NRS-score for leg and low back pain, a seven-point Global Perceived Effect (GPE) Scale and proportion of subsequential spinal surgery. Results: The number of patients that completed follow-up data after five years was 358 (82%): In the UL, BL and SPO group the numbers were 122, 119 and 117, respectively. Mean age at baseline was 66.7 (SD 8.2) years, mean BMI was 27.8 (SD 4.1), and 172/358 (48%) were female. In the UL group the mean change was  −18.2 (95% CI  −21.0  −5.4), in the BL group it was  −19.0 (95% CI -21.9–16.1) and in the SPO it was  −18.6 (95% CI  −21.6–15.7) (p = 0.917). No significant differences in the secondary outcomes between the three surgical groups were found, also the subsequent spinal surgery rates were similar. Conclusion: There were no significant differences in patient reported outcomes and subsequent spinal surgery rates after the three different decompression techniques at five-year follow-up.

• Hermansen, Erland; Myklebust, Tor Åge; Austevoll, Ivar Magne; Hellum, Christian; Storheim, Kjersti & Banitalebi, Hasan [Show all 8 contributors for this article] (2024). Dural Sac Cross-sectional area change from preoperatively and up to 2 years after decompressive surgery for central lumbar spinal stenosis: investigation of operated levels, data from the NORDSTEN study. European spine journal. ISSN 0940-6719. 33(6), p. 2234–2241. doi: 10.1007/s00586-024-08251-4. Full text in Research Archive Show summary

  Purpose The aim of the present study was to investigate how canal area size changed from before surgery and up to 2 years after decompressive lumbar surgery lumbar spinal stenosis. Further, to investigate if an area change postoperatively (between 3 months to 2 years) was associated with any preoperative demographic, clinical or MRI variables or surgical method used. Methods The present study is analysis of data from the NORDSTEN- SST trial where 437 patients were randomized to one of three mini-invasive surgical methods for lumbar spinal stenosis. The patients underwent MRI examination of the lumbar spine before surgery, and 3 and 24 months after surgery. For all operated segments the dural sac cross-sectional area (DSCA) was measured in mm2. Baseline factors collected included age, gender, BMI and smoking habits. Furthermore, surgical method, index level, number of levels operated, all levels operated on and baseline Schizas grade were also included in the analysis. Results 437 patients were enrolled in the NORDSTEN-SST trial, whereof 310 (71%) had MRI at 3 months and 2 years. Mean DSCA at index level was 52.0 mm2 (SD 21.2) at baseline, at 3 months it increased to 117.2 mm2 (SD 43.0) and after 2 years the area was 127.7 mm2 (SD 52.5). Surgical method, level operated on or Schizas did not influence change in DSCA from 3 to 24 months follow-up. Conclusion The spinal canal area after lumbar decompressive surgery for lumbar spinal stenosis increased from baseline to 3 months after surgery and remained thereafter unchanged 2 years postoperatively.

• Franssen, Eric; Weber, Clemens; Myklebust, Tor Åge; Austevoll, Ivar Magne; Brisby, Helena & Hellum, Christian [Show all 12 contributors for this article] (2024). Clinical importance of redundant nerve roots in patients with symptomatic lumbar spinal stenosis: A secondary analysis of NORDSTEN spinal stenosis trial data. Spine. ISSN 0362-2436. 50(14), p. 941–947. doi: 10.1097/BRS.0000000000005160. Full text in Research Archive Show summary

  Study Design. Post-hoc analysis of data from a randomized clinical trial. Objective. To compare preoperative symptoms of patients with lumbar spinal stenosis (LSS) with and without redundant nerve roots (RNR), and to compare the change in clinical outcomes between those two groups 2 years after decompression surgery. Summary of Background Data. RNR are often seen on MRI in patients with spinal stenosis. Previous studies have reported that patients with RNR are older and have worse symptoms at baseline. A meta-analysis from 2018 concluded that this radiological sign could be seen as a negative predictor of outcome. High quality prospective studies are lacking. Methods. Patient characteristics and reported pain and function scores were compared between LSS groups with (RNR+) and without RNR (RNR-) at baseline and after 2 years follow-up. Primary outcome was the mean change in the Oswestry Disability Score (ODI). Secondary outcomes included mean change in scores of the Zurich Claudication Questionnaire (ZCQ) and the numeric rating scale (NRS) for leg and back pain. Results. Out of 416 patients included in the present analysis, 163 (39%) had RNR at baseline. Both groups were similar in regard to patient age, smoking habits, BMI and duration of symptoms. Both groups also showed similar pain and function scores at baseline. The RNR+ group contained a significantly higher proportion of men, patients with severe stenosis and multiple stenotic levels on MRI. At 2-year follow-up the mean change of ODI was −22.1 in the RNR+ group and −17.4 in RNR- group (mean difference 4.7 (95%CI 1.3-8.2) P=0.007). Statistically significant differences were also found for secondary outcomes ZCQ, and NRS leg and back pain favouring the RNR+ group. Conclusion. Patients with RNR had similar baseline characteristics and similar symptoms as patients without. RNR before surgery were associated with better clinical improvement 2 years after decompression.

• Weber, Clemens; Hermansen, Erland; Myklebust, Tor Åge; Banitalebi, Hasan; Brisby, Helena & Brox, Jens Ivar [Show all 14 contributors for this article] (2024). Comparison of Patients Operated for Lumbar Spinal Stenosis with and Without Spondylolisthesis: A Secondary Analysis of the NORDSTEN Trials. Spine. ISSN 0362-2436. 49(19), p. 1332–1338. doi: 10.1097/BRS.0000000000005038. Full text in Research Archive Show summary

  Surgery Comparison of Patients Operated for Lumbar Spinal Stenosis With and Without Spondylolisthesis​​​​​ A Secondary Analysis of the NORDSTEN Trials Weber, Clemens MD, PhDa,b; Hermansen, Erland MD, PhDc,d; Myklebust, Tor Åge PhDe; Banitalebi, Hasan MDf,g; Brisby, Helena MD, PhDh,i; Brox, Jens I. MD, PhDj,k; Franssen, Eric MDl; Hellum, Christian MD, PhDm; Indrekvam, Kari MD, PhDd,n; Harboe, Knut MD, PhDd,l; Rekeland, Frode MDd,o; Solberg, Tore MD, PhDp,q; Storheim, Kjersti PhDr,s; Austevoll, Ivar M. MD, PhDd,o Author Information Spine 49(19):p 1332-1338, October 1, 2024. | DOI: 10.1097/BRS.0000000000005038 Buy SDC Metrics Abstract AI Summary Study Design. Observational cohort study (secondary analysis of two randomized trials). Objective. The aim of this study was to investigate whether function, disability, pain, and quality of life before surgery and patient-reported outcome as well as complication and reoperation rates up to 2 years after surgery differ between lumbar spinal stenosis patients with and

• Brisby, Helena; Myklebust, Tor Åge; Banitalebi, Hasan; Austevoll, Ivar Magne; Aaen, Jørn Ståle & Storheim, Kjersti [Show all 10 contributors for this article] (2024). Adjacent Level Canal Area Changes up to 2 years after Lumbar Spinal Stenosis Decompressive Surgery. Spine. ISSN 0362-2436. 50(7), p. 429–436. doi: 10.1097/BRS.0000000000005247. Full text in Research Archive Show summary

  Study Design: A secondary analysis of data from the NORDSTEN-spinal stenosis trial (SST). Objective: 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. Summary of Background Data: Decompressive surgery for LSS is currently the most common spinal surgery procedure; however, there is limited knowledge of changes in the DSCA over time adjacent to a decompressed segment. Materials and Methods: In the NORDSTEN-SST, 437 patients were randomized to decompression with one of three minimally invasive surgical methods for LSS. The patients underwent an 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, radiologic measures, and surgical method) for changes in the adjacent DSCA were examined using multivariate regression analyses. Results: Three hundred twenty-two 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 two years postoperatively, no decrease in adjacent DSCA was observed. No associations were found between the investigated baseline variables and DSCA change from zero to two years, except for a weak association with baseline adjacent DSCA. Conclusions: Up to two years postoperatively, the DSCA did not decrease at adjacent levels after decompressive surgery. None of the investigated baseline variables showed any clinically meaningful prognostic value regarding adjacent DSCA changes two years postoperatively. The findings support previous reports that decompression of adjacent levels is not required to prevent subsequent stenosis.

• Banitalebi, Hasan; Hermansen, Erland; Hellum, Christian; Espeland, Ansgar; Storheim, Kjersti & Myklebust, Tor Åge [Show all 12 contributors for this article] (2024). Preoperative fatty infiltration of paraspinal muscles assessed by MRI is associated with less improvement of leg pain 2 years after surgery for lumbar spinal stenosis. European spine journal. ISSN 0940-6719. 33(5), p. 1967–1978. doi: 10.1007/s00586-024-08210-z. Full text in Research Archive Show summary

  Purpose Fatty infiltration (FI) of the paraspinal muscles may associate with pain and surgical complications in patients with lumbar spinal stenosis (LSS). We evaluated the prognostic influence of MRI-assessed paraspinal muscles’ FI on pain or disability 2 years after surgery for LSS. Methods A muscle fat index (MFI) was calculated (by dividing signal intensity of psoas to multifidus and erector spinae) on preoperative axial T2-weighted MRI of patients with LSS. Pain and disability 2 years after surgery were assessed using the Oswestry disability index, the Zurich claudication questionnaire and numeric rating scales for leg and back pain. Multivariate linear and logistic regression analyses (adjusted for preoperative outcome scores, age, body mass index, sex, smoking status, grade of spinal stenosis, disc degeneration and facet joint osteoarthritis) were used to assess the associations between MFI and patient-reported clinical outcomes. In the logistic regression models, odds ratios (OR) and 95% confidence intervals (CI) were calculated for associations between the MFI and ≥ 30% improvement of the outcomes (dichotomised into yes/no). Results A total of 243 patients were evaluated (mean age 66.6 ± 8.5 years), 49% females (119). Preoperative MFI and postoperative leg pain were significantly associated, both with leg pain as continuous (coefficient − 3.20, 95% CI − 5.61, − 0.80) and dichotomised (OR 1.51, 95% CI 1.17, 1.95) scores. Associations between the MFI and the other outcome measures were not statistically significant. Conclusion Preoperative FI of the paraspinal muscles on MRI showed statistically significant association with postoperative NRS leg pain but not with ODI or ZCQ.

• Indrekvam, Kari; Myklebust, Tor Åge; Austevoll, Ivar Magne; Hermansen, Erland; Banitalebi, Hasan & Bånerud, Ingrid Fjeldheim [Show all 11 contributors for this article] (2024). Responsiveness of the Oswestry Disability Index and Zurich Claudication Questionnaire in patients with lumbar spinal stenosis: evaluation of surgically treated patients from the NORDSTEN study. European spine journal. ISSN 0940-6719. 33(11), p. 4270–4280. doi: 10.1007/s00586-024-08440-1. Full text in Research Archive Show summary

  Purpose To evaluate the responsiveness of the original low back pain specific Oswestry Disability Index (ODI) and the spinal stenosis specific Zürich Claudication Questionnaire (ZCQ), and to investigate cut-off values for clinical “success” for ODI and ZCQ in surgically treated patients with lumbar spinal stenosis (LSS). Methods We included 601 LSS patients (218 with, 383 without degenerative spondylolisthesis) from the NORDSTEN trials. Outcome measures included ODI and ZCQ (symptom severity and physical function scales) with three alternative response parameters: scores at follow-up, absolute and relative changes from baseline to two-year follow-up. Effect size and standardised response mean evaluated internal responsiveness. External responsiveness was assessed by the Spearman rank correlation between patient-reported global perceived effect scale (GPE) and ODI and ZCQ, and receiver operating characteristics (ROC). We evaluated which cut-off values could maximise the percentage of correctly classified pati

• Hellum, Christian; Rekeland, Frode Gurvin; Småstuen, Milada Cvancarova; Solberg, Tore; Hermansen, Erland & Storheim, Kjersti [Show all 17 contributors for this article] (2023). Surgery in Degenerative Spondylolisthesis: Does fusion improve outcome in subgroups? A secondary analysis from a randomized trial (NORDSTEN trial). The spine journal. ISSN 1529-9430. 23(11), p. 1613–1622. doi: 10.1016/j.spinee.2023.06.386. Full text in Research Archive Show summary

  Background context: Patients with spinal stenosis and degenerative spondylolisthesis are treated surgically with decompression alone or decompression with fusion. However, there is debate regarding which subgroups of patients may benefit from additional fusion. Purpose: To investigate possible treatment effect modifiers and prognostic variables among patients operated for spinal stenosis and degenerative spondylolisthesis. Design: A secondary exploratory study using data from the Norwegian Degenerative Spondylolisthesis and Spinal Stenosis (NORDSTEN-DS) trial. Patients were randomized to decompression alone or decompression with instrumented fusion. Patient sample: The sample in this study consists of 267 patients from a randomized multicenter trial involving 16 hospitals in Norway. Patients were enrolled from February 12, 2014, to December 18, 2017. The study did not include patients with degenerative scoliosis, severe foraminal stenosis, multilevel spondylolisthesis, or previous surgery. Outcome measures: The primary outcome was an improvement of ≥ 30% on the Oswestry Disability Index score (ODI) from baseline to 2-year follow-up. Methods: When investigating possible variables that could modify the treatment effect, we analyzed the treatment arms separately. When testing for prognostic factors we analyzed the whole cohort (both treatment groups). We used univariate and multiple regression analyses. The selection of variables was done a priori, according to the published trial protocol. Results: Of the 267 patients included in the trial (183 female [67%]; mean [SD] age, 66 [7.6] years), complete baseline data for the variables required for the present analysis were available for 205 of the 267 individuals. We did not find any clinical or radiological variables at baseline that modified the treatment effect. Thus, none of the commonly used criteria for selecting patients for fusion surgery influenced the chosen primary outcome in the two treatment arms. For the whole cohort, less comorbidity (American Society of Anesthesiologists Classification [ASA], OR = 4.35; 95% confidence interval (CI [1.16-16.67]) and more preoperative leg pain (OR = 1.23; CI [1.02-1.50]) were significantly associated with an improved primary outcome. Conclusions: In this study on patients with degenerative spondylolisthesis, neither previously defined instability criteria nor other pre-specified baseline variables were associated with better clinical outcome if fusion surgery was performed. None of the analyzed variables can be applied to guide the decision for fusion surgery in patients with degenerative spondylolisthesis. For both treatment groups, less comorbidity and more leg pain were associated with improved outcome 2 years after surgery. Trial registration: NORDSTEN-DS ClinicalTrials.gov, NCT02051374.

• Hermansen, Erland; Myklebust, Tor Åge; Weber, Clemens; Brisby, Helena; Austevoll, Ivar Magne & Hellum, Christian [Show all 15 contributors for this article] (2023). Postoperative Dural Sac Cross-Sectional Area as an Association for Outcome After Surgery for Lumbar Spinal Stenosis: Clinical and Radiological Results From the NORDSTEN-Spinal Stenosis Trial. Spine. ISSN 0362-2436. 48(10), p. 688–694. doi: 10.1097/BRS.0000000000004565. Full text in Research Archive Show summary

  Study Design. Prospective cohort study. Objective. The aim was to investigate the association between postoperative dural sac cross-sectional area (DSCA) after decompressive surgery for lumbar spinal stenosis and clinical outcome. Furthermore, to investigate if there is a minimum threshold for how extensive a posterior decompression needs to be to achieve a satisfactory clinical result. Summary of Background Data. There is limited scientific evidence for how extensive lumbar decompression needs to be to obtain a good clinical outcome in patients with symptomatic lumbar spinal stenosis. Materials and Methods. All patients were included in the Spinal Stenosis Trial of the NORwegian Degenerative spondylolisthesis and spinal STENosis (NORDSTEN)-study. The patients underwent decompression according to three different methods. DSCA measured on lumbar magnetic resonance imaging at baseline and at three months follow-up, and patient-reported outcome at baseline and at two-year follow-up were registered in a total of 393 patients. Mean age was 68 (SD: 8.3), proportion of males were 204/393 (52%), proportion of smokers were 80/393 (20%), and mean body mass index was 27.8 (SD: 4.2). The cohort was divided into quintiles based on the achieved DSCA postoperatively, the numeric, and relative increase of DSCA, and the association between the increase in DSCA and clinical outcome were evaluated. Results. At baseline, the mean DSCA in the whole cohort was 51.1 mm2 (SD: 21.1). Postoperatively the area increased to a mean area of 120.6 mm2 (SD: 46.9). The change in Oswestry disability index in the quintile with the largest DSCA was −22.0 (95% CI: −25.6 to −18), and in the quintile with the lowest DSCA the Oswestry disability index change was −18.9 (95% CI: −22.4 to −15.3). There were only minor differences in clinical improvement for patients in the different DSCA quintiles. Conclusion. Less aggressive decompression performed similarly to wider decompression across multiple different patient-reported outcome measures at two years following surgery.

• Riksaasen, Anniken; Kaur, Simran; Solberg, Tore; Austevoll, Ivar Magne; Brox, Jens Ivar & Dolatowski, Filip Celestyn [Show all 11 contributors for this article] (2023). Impact of the number of previous lumbar operations on patient-reported outcomes after surgery for lumbar spinal stenosis or lumbar disc herniation. The Bone & Joint Journal. ISSN 2049-4394. 105-B(4), p. 422–430. doi: 10.1302/0301-620X.105B4.BJJ-2022-0704.R1. Full text in Research Archive Show summary

  Repeated lumbar spine surgery has been associated with inferior clinical outcomes. This study aimed to examine and quantify the impact of this association in a national clinical register cohort. This is a population-based study from the Norwegian Registry for Spine surgery (NORspine). We included 26,723 consecutive cases operated for lumbar spinal stenosis or lumbar disc herniation from January 2007 to December 2018. The primary outcome was the Oswestry Disability Index (ODI), presented as the proportions reaching a patient-acceptable symptom state (PASS; defined as an ODI raw score ≤ 22) and ODI raw and change scores at 12-month follow-up. Secondary outcomes were the Global Perceived Effect scale, the numerical rating scale for pain, the EuroQoL five-dimensions health questionnaire, occurrence of perioperative complications and wound infections, and working capability. Binary logistic regression analysis was conducted to examine how the number of previous operations influenced the odds of not reaching a PASS. The proportion reaching a PASS decreased from 66.0% (95% confidence interval (CI) 65.4 to 66.7) in cases with no previous operation to 22.0% (95% CI 15.2 to 30.3) in cases with four or more previous operations (p < 0.001). The odds of not reaching a PASS were 2.1 (95% CI 1.9 to 2.2) in cases with one previous operation, 2.6 (95% CI 2.3 to 3.0) in cases with two, 4.4 (95% CI 3.4 to 5.5) in cases with three, and 6.9 (95% CI 4.5 to 10.5) in cases with four or more previous operations. The ODI raw and change scores and the secondary outcomes showed similar trends. We found a dose-response relationship between increasing number of previous operations and inferior outcomes among patients operated for degenerative conditions in the lumbar spine. This information should be considered in the shared decision-making process prior to elective spine surgery. © 2023 Author(s) et al.

• Aaen, Jørn Ståle; Banitalebi, Hasan; Austevoll, Ivar Magne; Hellum, Christian; Storheim, Kjersti & Myklebust, Tor Åge [Show all 13 contributors for this article] (2023). Is the presence of foraminal stenosis associated with outcome in lumbar spinal stenosis patients treated with posterior microsurgical decompression. Acta Neurochirurgica. ISSN 0001-6268. 165(8), p. 2121–2129. doi: 10.1007/s00701-023-05693-5. Full text in Research Archive Show summary

  Background We aim to investigate associations between preoperative radiological findings of lumbar foraminal stenosis with clinical outcomes after posterior microsurgical decompression in patients with predominantly central lumbar spinal stenosis (LSS). Methods The study was an additional analysis in the NORDSTEN Spinal Stenosis Trial. In total, 230 men and 207 women (mean age 66.8 (SD 8.3)) were included. All patients underwent an MRI including T1- and T2-weighted sequences. Grade of foraminal stenosis was dichotomized into none to moderate (0–1) and severe (2–3) category using Lee’s classification system. The Oswestry Disability Index (ODI), Zurich Claudication Questionnaire (ZCQ), and numeric rating scale (NRS) for back and leg pain were collected at baseline and at 2-year follow-up. Primary outcome was a reduction of 30% or more on the ODI score. Secondary outcomes included the mean improvement on the ODI, ZCQ, and NRS scores. We performed multivariable regression analyses with the radiological variates foraminal stenosis, Pfirrmann grade, Schizas score, dural sac cross-sectional area, and the possible plausible confounders: patients’ gender, age, smoking status, and BMI. Results The cohort of 437 patients presented a high degree of degenerative changes at baseline. Of 414 patients with adequate imaging of potential foraminal stenosis, 402 were labeled in the none to moderate category and 12 in the severe category. Of the patients with none to moderate foraminal stenosis, 71% achieved at least 30% improvement in ODI. Among the patients with severe foraminal stenosis, 36% achieved at least 30% improvement in ODI. A significant association between severe foraminal stenosis and less chance of reaching the target of 30% improvement in the ODI score after surgery was detected: OR 0.22 (95% CI 0.06, 0.83), p=0.03. When investigating outcome as continuous variables, a similar association between severe foraminal stenosis and less improved ODI with a mean difference of 9.28 points (95%CI 0.47, 18.09; p=0.04) was found. Significant association between severe foraminal stenosis and less improved NRS pain in the lumbar region was also detected with a mean difference of 1.89 (95% CI 0.30, 3.49; p=0.02). No significant association was suggested between severe foraminal stenosis and ZCQ or NRS leg pain. Conclusion In patients operated with posterior microsurgical decompression for LSS, a preoperative severe lumbar foraminal stenosis was associated with higher proportion of patients with less than 30% improvement in ODI.

• Indrekvam, Kari; Bånerud, Ingrid Fjeldheim; Hermansen, Erland; Austevoll, Ivar Magne; Rekeland, Frode Gurvin & Guddal, Maren Hjelle [Show all 10 contributors for this article] (2023). The Norwegian degenerative spondylolisthesis and spinal stenosis (NORDSTEN) study: study overview, organization structure and study population. European spine journal. ISSN 0940-6719. 32(12), p. 4162–4173. doi: 10.1007/s00586-023-07827-w. Full text in Research Archive Show summary

  Purpose To provide an overview of the The Norwegian Degenerative spondylolisthesis and spinal stenosis (NORDSTEN)-study and the organizational structure, and to evaluate the study population. Methods The NORDSTEN is a multicentre study with 10 year follow-up, conducted at 18 public hospitals. NORDSTEN includes three studies: (1) The randomized spinal stenosis trial comparing the impact of three different decompression techniques; (2) the randomized degenerative spondylolisthesis trial investigating whether decompression surgery alone is as good as decompression with instrumented fusion; (3) the observational cohort tracking the natural course of LSS in patients without planned surgical treatment. A range of clinical and radiological data are collected at defined time points. To administer, guide, monitor and assist the surgical units and the researchers involved, the NORDSTEN national project organization was established. Corresponding clinical data from the Norwegian Registry for Spine Surgery (NORspine) were used to assess if the randomized NORDSTEN-population at baseline was representative for LSS patients treated in routine surgical practice. Results A total of 988 LSS patients with or without spondylolistheses were included from 2014 to 2018. The clinical trials did not find any difference in the efficacy of the surgical methods evaluated. The NORDSTEN patients were similar to those being consecutively operated at the same hospitals and reported to the NORspine during the same time period. Conclusion The NORDSTEN study provides opportunity to investigate clinical course of LSS with or without surgical interventions. The NORDSTEN-study population were similar to LSS patients treated in routine surgical practice, supporting the external validity of previously published results.

• Espeland, Ansgar; Kristoffersen, Per Martin; Bråten, Lars Christian Haugli; Grøvle, Lars; Grotle, Margreth & Haugen, Anne Julsrud [Show all 12 contributors for this article] (2023). Longitudinal Relationship Between Reduced Modic Change Edema and Disability and Pain in Patients With Chronic Low Back Pain. Spine. ISSN 0362-2436. 48(24), p. 1699–1708. doi: 10.1097/BRS.0000000000004837. Full text in Research Archive Show summary

  Study Design. Secondary analyses of a randomized trial [Antibiotics In Modic changes (MCs) study]. Objective. To assess whether or not reduced MC edema over time is related to reduced disability and pain in patients with chronic low back pain (LBP). Summary of Background Data. It is not clear whether or not reduced MC edema implies improved clinical outcomes. Patients and Methods. Linear regression was conducted separately in 2 subgroups with MC edema at baseline on short tau inversion recovery (STIR) or T1/T2-weighted magnetic resonance imaging, respectively. Independent variable: reduced edema (yes/no) at 1 year on STIR or T1/T2-series, respectively. Dependent variable: 1-year score on the Roland-Morris Disability Questionnaire (RMDQ), Oswestry Disability Index (ODI), or 0 to 10 numeric rating scale for LBP intensity, adjusted for the baseline score, age, smoking, body mass index, physical workload, and baseline edema on STIR (STIR analysis only). Post hoc, we, in addition, adjusted all analyses for baseline edema on STIR, treatment group (amoxicillin/placebo), and prior disc surgery—or for disc degeneration. Results. Among patients with MC edema on STIR at baseline (n = 162), reduced edema on STIR was not significantly related to the RMDQ (B: −1.0, 95% CI: −2.8, 0.8; P = 0.27), ODI (B:−1.4, 95% CI: −5.4, 2.6; P = 0.50), or LBP intensity scores (B: −0.05, 95% CI: −0.8, 0.7; P = 0.90) after 1 year. Among patients with MC edema on T1/T2-series at baseline (n = 116), reduced edema on T1/T2 (i.e., reduced volume of the type 1 part of MCs) was not significantly related to RMDQ (B: −1.7, 95% CI: −3.8, 0.3; P = 0.10) or ODI score (B: −2.3, 95% CI: −7.1, 2.5; P = 0.34) but was significantly related to LBP intensity at 1 year (B: −0.9, 95% CI: −1.8, −0.04; P = 0.04; correlation coefficient: 0.24). The post hoc analyses supported these results. Conclusion. Reduced MC edema over 1 year was not significantly associated with pain-related disability but was (on T1/T2-series) significantly but weakly related to reduced LBP intensity.

• Mikkelsen, Eirik; Ingebrigtsen, Tor; Thyrhaug, Anette Moltu; Olsen, Lena Ringstad; Nygaard, Øystein Petter & Austevoll, Ivar Magne [Show all 11 contributors for this article] (2023). The Norwegian registry for spine surgery (NORspine): cohort profile. European spine journal. ISSN 0940-6719. 32(11). doi: 10.1007/s00586-023-07929-5. Full text in Research Archive Show summary

  Purpose: To review and describe the development, methods and cohort of the lumbosacral part of the Norwegian registry for spine surgery (NORspine). Methods: NORspine was established in 2007. It is government funded, covers all providers and captures consecutive cases undergoing operations for degenerative disorders. Patients' participation is voluntary and requires informed consent. A set of baseline-, process- and outcome-variables (3 and 12 months) recommended by the International Consortium for Health Outcome Measurement is reported by surgeons and patients. The main outcome is the Oswestry disability index (ODI) at 12 months. Results: We show satisfactory data quality assessed by completeness, timeliness, accuracy, relevance and comparability. The coverage rate has been 100% since 2016 and the capture rate has increased to 74% in 2021. The cohort consists of 60,647 (47.6% women) cases with mean age 55.7 years, registered during the years 2007 through 2021. The proportions > 70 years and with an American Society of Anaesthesiologists' Physical Classification System (ASA) score > II has increased gradually to 26.1% and 19.3%, respectively. Mean ODI at baseline was 43.0 (standard deviation 17.3). Most cases were operated with decompression for disc herniation (n = 26,557, 43.8%) or spinal stenosis (n = 26,545, 43.8%), and 7417 (12.2%) with additional or primary fusion. The response rate at 12 months follow-up was 71.6%. Conclusion: NORspine is a well-designed population-based comprehensive national clinical quality registry. The register's methods ensure appropriate data for quality surveillance and improvement, and research.

• Aaen, Jørn Ståle; Banitalebi, Hasan; Austevoll, Ivar Magne; Hellum, Christian; Storheim, Kjersti & Myklebust, Tor Åge [Show all 13 contributors for this article] (2022). The association between preoperative MRI findings and clinical improvement in patients included in the NORDSTEN spinal stenosis trial. European spine journal. ISSN 0940-6719. 31(10), p. 2777–2785. doi: 10.1007/s00586-022-07317-5. Full text in Research Archive Show summary

  Purpose To investigate potential associations between preoperative MRI findings and patient reported outcome measures (PROMs) after surgery for lumbar spinal stenosis (LSS). Methods The NORDSTEN trial included 437 patients. We investigated the association between preoperative MRI findings such as morphological grade of stenosis (Schizas grade), quantitative grade of stenosis (dural sac cross-sectional area), disc degeneration (Pfirrmann score), facet joint tropism and fatty infiltration of the multifidus muscle, and improvement in patient reported outcome measures (PROMs) 2 years after surgery. We dichotomized each radiological parameter into a moderate or severe category. PROMs i.e., Oswestry Disability Index (ODI), Zurich Claudication Questionnaire (ZCQ) and Numeric rating scale (NRS) for back and leg pain were collected before surgery and at 2 year follow-up. In the primary analysis, we investigated the association between MRI findings and ODI score (dichotomized to ≥ 30% improvement or not). In the secondary analysis, we investigated the association between MRI findings and the mean improvement on the ODI-, ZCQ- and NRS scores. We used multivariable regression models adjusted for patients’ gender, age, smoking status and BMI. Results The primary analysis showed that severe disc degeneration (Pfirrmann score 4–5) was significantly associated with less chance of achieving a 30% improvement on the ODI score (OR 0.54, 95% CI 0.34, 0.88). In the secondary analysis, we detected no clinical relevant associations. Conclusion Severe disc degeneration preoperatively suggest lesser chance of achieving 30% improvement in ODI score after surgery for LSS. Other preoperative MRI findings were not associated with patient reported outcome.

• Banitalebi, Hasan; Aaen, Jørn Ståle; Storheim, Kjersti; Negård, Anne; Myklebust, Tor Åge & Grotle, Margreth [Show all 14 contributors for this article] (2022). A novel MRI index for paraspinal muscle fatty infiltration: reliability and relation to pain and disability in lumbar spinal stenosis: results from a multicentre study. European Radiology Experimental. 6(1), p. 1–10. doi: 10.1186/s41747-022-00284-y. Full text in Research Archive Show summary

  Background Fatty infiltration of the paraspinal muscles may play a role in pain and disability in lumbar spinal stenosis. We assessed the reliability and association with clinical symptoms of a method for assessing fatty infiltration, a simplified muscle fat index (MFI). Methods Preoperative axial T2-weighted magnetic resonance imaging (MRI) scans of 243 patients aged 66.6 ± 8.5 years (mean ± standard deviation), 119 females (49%), with symptomatic lumbar spinal stenosis were assessed. Fatty infiltration was assessed using both the MFI and the Goutallier classification system (GCS). The MFI was calculated as the signal intensity of the psoas muscle divided by that of the multifidus and erector spinae. Observer reliability was assessed in 102 consecutive patients for three independent investigators by intraclass correlation coefficient (ICC) and 95% limits of agreement (LoA) for continuous variables and Gwet’s agreement coefficient (AC1) for categorical variables. Associations with patient-reported pain and disability were assessed using univariate and multivariate regression analyses. Results Interobserver reliability was good for the MFI (ICC 0.79) and fair for the GCS (AC1 0.33). Intraobserver reliability was good or excellent for the MFI (ICC range 0.86–0.91) and moderate to almost perfect for the GCS (AC1 range 0.55–0.92). Mean interobserver differences of MFI measurements ranged from -0.09 to -0.04 (LoA -0.32 to 0.18). Adjusted for potential confounders, none of the disability or pain parameters was significantly associated with MFI or GCS. Conclusion The proposed MFI demonstrated high observer reliability but was not associated with preoperative pain or disability.

• Banitalebi, Hasan; Espeland, Ansgar; Anvar, Masoud D; Hermansen, Erland; Hellum, Christian & Brox, Jens Ivar [Show all 14 contributors for this article] (2022). Reliability of preoperative MRI findings in patients with lumbar spinal stenosis. BMC Musculoskeletal Disorders. 23(1), p. 1–9. doi: 10.1186/s12891-021-04949-4. Full text in Research Archive Show summary

  Background Magnetic Resonance Imaging (MRI) is an important tool in preoperative evaluation of patients with lumbar spinal stenosis (LSS). Reported reliability of various MRI findings in LSS varies from fair to excellent. There are inconsistencies in the evaluated parameters and the methodology of the studies. The purpose of this study was to evaluate the reliability of the preoperative MRI findings in patients with LSS between musculoskeletal radiologists and orthopaedic spine surgeons, using established evaluation methods and imaging data from a prospective trial. Methods Consecutive lumbar MRI examinations of candidates for surgical treatment of LSS from the Norwegian Spinal Stenosis and Degenerative Spondylolisthesis (NORDSTEN) study were independently evaluated by two musculoskeletal radiologists and two orthopaedic spine surgeons. The observers had a range of experience between six and 13 years and rated five categorical parameters (foraminal and central canal stenosis, facet joint osteoarthritis, redundant nerve roots and intraspinal synovial cysts) and one continuous parameter (dural sac cross-sectional area). All parameters were re-rated after 6 weeks by all the observers. Inter- and intraobserver agreement was assessed by Gwet’s agreement coefficient (AC1) for categorical parameters and Intraclass Correlation Coefficient (ICC) for the dural sac cross-sectional area. Results MRI examinations of 102 patients (mean age 66 ± 8 years, 53 men) were evaluated. The overall interobserver agreement was substantial or almost perfect for all categorical parameters (AC1 range 0.67 to 0.98), except for facet joint osteoarthritis, where the agreement was moderate (AC1 0.39). For the dural sac cross-sectional area, the overall interobserver agreement was good or excellent (ICC range 0.86 to 0.96). The intraobserver agreement was substantial or almost perfect/ excellent for all parameters (AC1 range 0.63 to 1.0 and ICC range 0.93 to 1.0). Conclusions There is high inter- and intraobserver agreement between radiologists and spine surgeons for preoperative MRI findings of LSS. However, the interobserver agreement is not optimal for evaluation of facet joint osteoarthritis.

• Hermansen, Erland; Austevoll, Ivar Magne; Hellum, Christian; Storheim, Kjersti; Myklebust, Tor Åge & Aaen, Jørn Ståle [Show all 17 contributors for this article] (2022). Comparison of 3 Different Minimally Invasive Surgical Techniques for Lumbar Spinal Stenosis: A Randomized Clinical Trial. JAMA Network Open. 5(3), p. 1–13. doi: 10.1001/jamanetworkopen.2022.4291. Full text in Research Archive Show summary

  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.

• Garratt, Andrew M.; Furunes, Håvard; Hellum, Christian; Solberg, Tore; Brox, Jens Ivar & Storheim, Kjersti [Show all 7 contributors for this article] (2021). Evaluation of the EQ-5D-3L and 5L versions in low back pain patients. Health and Quality of Life Outcomes. 19. doi: 10.1186/s12955-021-01792-y. Full text in Research Archive Show summary

  Background The EuroQol EQ-5D is one of the most widely researched and applied patient-reported outcome measures worldwide. The original EQ-5D-3L and more recent EQ-5D-5L include three and five response categories respectively. Evidence from healthy and sick populations shows that the additional two response categories improve measurement properties but there has not been a concurrent comparison of the two versions in patients with low back pain (LBP). Methods LBP patients taking part in a multicenter randomized controlled trial of lumbar total disc replacement and conservative treatment completed the EQ-5D-3L and 5L in an eight-year follow-up questionnaire. The 3L and 5L were assessed for aspects of data quality including missing data, floor and ceiling effects, response consistency, and based on a priori hypotheses, associations with the Oswestry Disability Index (ODI), Pain-Visual Analogue Scales and Hopkins Symptom Checklist (HSCL-25). Results At the eight-year follow-up, 151 (87%) patients were available and 146 completed both the 3L and 5L. Levels of missing data were the same for the two versions. Compared to the EQ-5D-5L, the 3L had significantly higher floor (pain discomfort) and ceiling effects (mobility, self-care, pain/discomfort, anxiety/depression). For these patients the EQ-5D-5L described 73 health states compared to 28 for the 3L. Shannon’s indices showed the 5L outperformed the 3L in tests of classification efficiency. Correlations with the ODI, Pain-VAS and HSCL-25 were largely as hypothesized, the 5L having slightly higher correlations than the 3L. Conclusion The EQ-5D assesses important aspect of health in LBP patients and the 5L improves upon the 3L in this respect. The EQ-5D-5L is recommended in preference to the 3L version, however, further testing in other back pain populations together with additional measurement properties, including responsiveness to change, is recommended. © The Author(s) 2021. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.

• Aaen, Jørn; Austevoll, Ivar Magne; Hellum, Christian; Storheim, Kjersti; Myklebust, Tor Åge & Banitalebi, Hasan [Show all 14 contributors for this article] (2021). Clinical and MRI findings in lumbar spinal stenosis: baseline data from the NORDSTEN study. European spine journal. ISSN 0940-6719. doi: 10.1007/s00586-021-07051-4. Full text in Research Archive Show summary

  Purpose The aim was to describe magnetic resonance imaging fndings in patients planned for lumbar spinal stenosis surgery. Further, to describe possible associations between MRI fndings and patient characteristics with patient reported disability or pain. Methods The NORDSTEN spinal stenosis trial included 437 patients planned for surgical decompression of LSS. The following MRI fndings were evaluated before surgery: morphological (Schizas) and quantitative (cross-sectional area) grade of stenosis, disk degeneration (Pfrrmann), facet joint tropism and fatty infltration of the multifdus muscle. Patients were dichotomized into a moderate or severe category for each radiological parameter classifcation. A multivariable linear regression analysis was performed to investigate the association between MRI fndings and preoperative scores for Oswestry Disability Index, Zurich Claudication Questionnaire and Numeric rating scale for back and leg pain. The following patient characteristics were included in the analysis: gender, age, smoking and weight. Results The percentage of patients with severe scores was as follows: Schizas (C+D) 71.3%, cross-sectional area (<75 mm2 ) 86.8%, Pfrrmann (4+5) 58.1%, tropism (≥15°) 11.9%, degeneration of multifdus muscle (2–4) 83.7%. Regression coefcients indicated minimal changes in severity of symptoms when comparing the groups with moderate and severe MRI fndings. Only gender had a signifcant and clinically relevant association with ODI score. Conclusion In this cross-sectional study, the majority of the patients had MRI fndings classifed as severe LSS changes, but the fndings had no clinically relevant association with patient reported disability and pain at baseline. Patient characteristics have a larger impact on disability and pain than radiological fndings. Trial registration www.ClinicalTrials.gov identifer: NCT02007083, registered December 2013. Keywords Lumbar spinal stenosis · Schizas · DSCA · Pfrrmann · Tropism

• Austevoll, Ivar Magne; Hermansen, Erland; Fagerland, Morten Wang; Storheim, Kjersti; Brox, Jens Ivar & Solberg, Tore [Show all 16 contributors for this article] (2021). Decompression with or without Fusion in Degenerative Lumbar Spondylolisthesis. New England Journal of Medicine. ISSN 0028-4793. 385(6), p. 526–538. doi: 10.1056/NEJMoa2100990. Full text in Research Archive Show summary

  BACKGROUND In patients with lumbar spinal stenosis and degenerative spondylolisthesis, it is uncertain whether decompression surgery alone is noninferior to decompression with instrumented fusion. METHODS We conducted an open-label, multicenter, noninferiority trial involving patients with symptomatic lumbar stenosis that had not responded to conservative management and who had single-level spondylolisthesis of 3 mm or more. Patients were randomly assigned in a 1:1 ratio to undergo decompression surgery (decompressionalone group) or decompression surgery with instrumented fusion (fusion group). The primary outcome was a reduction of at least 30% in the score on the Oswestry Disability Index (ODI; range, 0 to 100, with higher scores indicating more impairment) during the 2 years after surgery, with a noninferiority margin of −15 percentage points. Secondary outcomes included the mean change in the ODI score as well as scores on the Zurich Claudication Questionnaire, leg and back pain, the duration of surgery and length of hospital stay, and reoperation within 2 years. RESULTS The mean age of patients was approximately 66 years. Approximately 75% of the patients had leg pain for more than a year, and more than 80% had back pain for more than a year. The mean change from baseline to 2 years in the ODI score was −20.6 in the decompression-alone group and −21.3 in the fusion group (mean difference, 0.7; 95% confidence interval [CI], −2.8 to 4.3). In the modified intentionto- treat analysis, 95 of 133 patients (71.4%) in the decompression-alone group and 94 of 129 patients (72.9%) in the fusion group had a reduction of at least 30% in the ODI score (difference, −1.4 percentage points; 95% CI, −12.2 to 9.4), showing the noninferiority of decompression alone. In the per-protocol analysis, 80 of 106 patients (75.5%) and 83 of 110 patients (75.5%), respectively, had a reduction of at least 30% in the ODI score (difference, 0.0 percentage points; 95% CI, −11.4 to 11.4), showing noninferiority. The results for the secondary outcomes were generally in the same direction as those for the primary outcome. Successful fusion was achieved with certainty in 86 of 100 patients (86.0%) who had imaging available at 2 years. Reoperation was performed in 15 of 120 patients (12.5%) in the decompression- alone group and in 11 of 121 patients (9.1%) in the fusion group. CONCLUSIONS In this trial involving patients who underwent surgery for degenerative lumbar spondylolisthesis, most of whom had symptoms for more than a year, decompression alone was noninferior to decompression with instrumented fusion over a period of 2 years. Reoperation occurred somewhat more often in the decompressionalone group than in the fusion group. (NORDSTEN-DS ClinicalTrials.gov number, NCT02051374.)

• Bråten, Lars Christian Haugli; Grøvle, Lars; Espeland, Ansgar; Pripp, Are Hugo; Grotle, Margreth & Hellum, Christian [Show all 18 contributors for this article] (2020). Clinical effect modifiers of antibiotic treatment in patients with chronic low back pain and Modic changes - Secondary analyses of a randomised, placebo-controlled trial (the AIM study). BMC Musculoskeletal Disorders. 21, p. 1–11. doi: 10.1186/s12891-020-03422-y. Full text in Research Archive Show summary

  Background: Randomised trials on antibiotic treatment for patients with chronic low back pain and vertebral endplate changes visible on MRI (Modic changes) have shown mixed results. A possible explanation might be a real treatment effect in subgroups of the study populations. The purpose of the present study was to explore potential clinical effect modifiers of 3-months oral amoxicillin treatment in patients with chronic low back pain and type I or II Modic changes at the level of a previous lumbar disc herniation. Methods: We performed analyses of effect modifiers on data from AIM, a double-blind parallel-group multicentre trial. One hundred eighty patients with chronic low back pain, previous disc herniation, Modic change type I (n = 118) or type II (n = 62) were randomised to 3-months oral treatment with 750 mg amoxicillin (n = 89) or placebo (n = 91) three times daily. The primary outcome was the Roland-Morris Disability Questionnaire (RMDQ) score (possible values 0–24) at 1-year follow-up in the intention-to-treat population. The predefined minimal clinically important between-group mean difference was 4 RMDQ points (not reached in the primary analysis of AIM). Predefined baseline characteristics were analysed as potential effect modifiers, four primary (type I Modic changes, previous disc surgery, positive pain provocation test, high CRP) and five exploratory (disturbed sleep, constant low back pain, short duration of low back pain, younger age, and male) using ANCOVA with interaction terms. Results: None of the four primary potential effect modifiers had strong evidence of modifying the treatment effect. In patients younger than 40 years the difference in mean RMDQ score between the treatment groups was − 4.0 (95%CI, − 6.9 to − 1.2), compared to − 0.5 (95%CI, − 2.3 to 1.3) in patients 40 years or older, both in favour of amoxicillin treatment (exploratory analysis). Conclusions: We did not find evidence for convincing clinical effect modifiers of antibiotic treatment in patients with chronic low back pain and Modic changes. Our results for younger age in these explorative analyses should not affect clinical treatment decisions without confirmation in future studies.

• Austevoll, Ivar Magne; Gjestad, Rolf; Solberg, Tore; Storheim, Kjersti; Brox, Jens Ivar & Hermansen, Erland [Show all 9 contributors for this article] (2020). Comparative effectiveness of microdecompression alone vs decompression plus instrumented fusion in lumbar degenerative spondylolisthesis. JAMA Network Open. 3:e2015015(9), p. 1–13. doi: 10.1001/jamanetworkopen.2020.15015. Full text in Research Archive Show summary

  Importance Conflicting evidence and large practice variation are present in the surgical treatment of degenerative spondylolisthesis. More than 90% of surgical procedures in the United States include instrumented fusion compared with 50% or less in other countries. Objective To evaluate whether the effectiveness of microdecompression alone is noninferior to decompression with instrumented fusion in a real-world setting. Design, Setting, and Participants This multicenter comparative effectiveness study with a noninferiority design assessed prospective data from the Norwegian Registry for Spine Surgery. From September 19, 2007, to December 21, 2015, 1376 patients at 35 Norwegian orthopedic and neurosurgical departments underwent surgery for lumbar spinal stenosis with degenerative spondylolisthesis without scoliosis. After excluding patients undergoing laminectomy alone, fusion without instrumentation, or surgery in more than 2 levels and those with a former operation at the index level, 794 patients were included in the analyses, regardless of missing or incomplete follow-up data, before propensity score matching. Data were analyzed from March 20 to October 30, 2018. Exposures Microdecompression alone or decompression with instrumented fusion. Main Outcomes and Measures A reduction from baseline of 30% or greater in the Oswestry Disability Index at 12-month follow-up. Results After propensity score matching, 570 patients (413 female [72%]; mean [SD] age, 64.7 [9.5] years) were included for comparison, with 285 undergoing microdecompression (mean [SD] age, 64.6 [9.8] years; 205 female [72%]) and 285 undergoing decompression with instrumented fusion (mean [SD] age, 64.8 [9.2] years; 208 female [73%]). The proportion of each type of procedure varied between departments. However, changes in outcome scores varied within patients but not between departments. The proportion of patients with improvement in the Oswestry Disability Index of at least 30% was 150 of 219 (68%) in the microdecompression group and 155 of 215 (72%) in the instrumentation group. The 95% CI (–12% to 5%) for the difference of −4% was above the predefined margin of noninferiority (–15%). Microdecompression alone was associated with shorter operation time (mean [SD], 89 [44] vs 180 [65] minutes; P < .001) and shorter hospital stay (mean [SD], 2.5 [2.4] vs 6.4 [3.0] days; P < .001). Conclusions and Relevance Among patients with degenerative spondylolisthesis, the clinical effectiveness of microdecompression alone was noninferior to that of decompression with instrumented fusion. Microdecompression alone was also associated with shorter durations of surgery and hospital stay, supporting the suggestion that the less invasive procedure should be considered for most patients.

• Furunes, Håvard; Berg, Linda; Espeland, Ansgar; Thoresen, Hanne; Neckelmann, Gesche F & Brøgger, Helga Maria [Show all 10 contributors for this article] (2020). Facet arthropathy following disc replacement versus rehabilitation: A prospective study with 8-year follow-up. Spine. ISSN 0362-2436. 45(21), p. 1467–1475. doi: 10.1097/BRS.0000000000003600. Full text in Research Archive Show summary

  Study design: A prospective study of patients originally randomized to total disc replacement (TDR) or multidisciplinary rehabilitation. Objective: To assess the long-term development of facet arthropathy (FA) after TDR versus nonoperative treatment, and to analyze the association between FA and clinical outcome. Summary of background data: FA may appear or increase following TDR, but the natural course of FA is unclear, and no previous study has evaluated the long-term development of FA following TDR compared with nonoperative treatment. Methods: The study included 126 patients with chronic low back pain and degenerative changes in the lumbar intervertebral discs. The patients underwent pretreatment and 8-year follow-up magnetic resonance imaging (MRI) and 8-year follow-up computed tomography (CT) of the lumbar spine. The primary outcome measure was FA development (yes/no) on MRI at index level L4/L5 or L5/S1, defined as increased FA grade value from pretreatment to follow-up according to Weishaupt grading system. Secondary outcomes included the association between FA (on MRI and CT) and Oswestry Disability Index (ODI) or back pain as well as reoperations. Results: Increased index level FA grade was more frequent after TDR versus nonoperative treatment (36%, 25/69 vs. 2%, 1/57 of patients, P < 0.001), but was not related to change in ODI or back pain. At follow-up, index level FA grades were higher after TDR versus nonoperative treatment (odds ratio 4.0 MRI and 5.9 CT), but were not related to ODI less than or equal to 22. Four patients (6%) treated with TDR and no patients treated nonoperatively were operated for lateral recess stenosis with posterior decompression at the index level during follow-up. Conclusion: Index level FA development was more likely after TDR compared with nonoperative treatment but was not associated with the 8-year clinical outcome. Index level FA may have contributed to reoperations in the TDR group. Level of evidence: 2.

• Kristoffersen, Per M; Bråten, Lars Christian Haugli; Vetti, Nils; Grøvle, Lars; Hellum, Christian & Storheim, Kjersti [Show all 9 contributors for this article] (2020). Oedema on STIR modified the effect of amoxicillin as treatment for chronic low back pain with Modic changes-subgroup analysis of a randomized trial. European Radiology. ISSN 0938-7994. 31. doi: 10.1007/s00330-020-07542-w. Full text in Research Archive Show summary

  Objective To evaluate potential MRI-defined effect modifiers of amoxicillin treatment in patients with chronic low back pain and type 1 or 2 Modic changes (MCs) at the level of a previous lumbar disc herniation (index level). Methods In a prospective trial (AIM), 180 patients (25–64 years; mean age 45; 105 women) were randomised to receive amoxicillin or placebo for 3 months. Primary outcome was the Roland-Morris Disability Questionnaire (RMDQ) score (0–24 scale) at 1 year. Mean RMDQ score difference between the groups at 1 year defined the treatment effect; 4 RMDQ points defined the minimal clinically important effect. Predefined baseline MRI features of MCs at the index level(s) were investigated as potential effect modifiers. The predefined primary hypothesis was a better effect of amoxicillin when short tau inversion recovery (STIR) shows more MC-related high signal. To evaluate this hypothesis, we pre-constructed a composite variable with three categories (STIR1/2/3). STIR3 implied MC-related STIR signal increases with volume ≥ 25% and height > 50% of vertebral body and maximum intensity increase ≥ 25% and presence on both sides of the disc. As pre-planned, interaction with treatment was analysed using ANCOVA in the per protocol population (n = 155). Results The STIR3 composite group (n = 41) and STIR signal volume ≥ 25% alone (n = 45) modified the treatment effect of amoxicillin. As hypothesised, STIR3 patients reported the largest effect (− 5.1 RMDQ points; 95% CI − 8.2 to − 1.9; p for interaction = 0.008). Conclusions Predefined subgroups with abundant MC-related index-level oedema on STIR modified the effect of amoxicillin. This finding needs replication and further support. Key Points • In the primary analysis of the AIM trial, the effect of amoxicillin in patients with chronic low back pain and type 1 or 2 MCs did not reach the predefined cut-off for clinical importance. • In the present MRI subgroup analysis of AIM, predefined subgroups with abundant MC-related oedema on STIR reported an effect of amoxicillin. • This finding requires replication and further support.

• Hermansen, Erland; Austevoll, Ivar Magne; Hellum, Christian; Storheim, Kjersti; Myklebust, Tor Åge & Aaen, Jørn Ståle [Show all 17 contributors for this article] (2020). 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. European spine journal. ISSN 0940-6719. 29, p. 2254–2261. doi: 10.1007/s00586-020-06499-0. Full text in Research Archive Show summary

  Purpose: To investigate changes in dural sac area after three different posterior decompression techniques in patients undergoing surgery for lumbar spinal stenosis. Summary of background data: Decompression of the nerve roots is the main surgical treatment for lumbar spinal stenosis. The aim of this study was to radiologically investigate three commonly used posterior decompression techniques. Methods: The present study reports data from one of two multicenter randomized trials included in the NORDSTEN study. In the present trial, involving 437 patients undergoing surgery, we report radiological results after three different midline retaining posterior decompression techniques: unilateral laminotomy with crossover (UL) (n = 146), bilateral laminotomy (BL) (n = 142) and spinous process osteotomy (SPO) (n = 149). MRI was performed before and three months after surgery. The increase in dural sac area and Schizas grade at the most stenotic level was evaluated. Three different predefined surgical indicators of substantial decompression were used: (1) postoperative dural sac area of > 100 mm2, (2) increase in the dural sac area of at least 50% and (3) postoperative Schizas grade A or B. Results: No differences between the three surgical groups were found in the mean increase in dural sac area. Mean values were 66.0 (SD 41.5) mm2 in the UL-group, 71.9 (SD 37.1) mm2 in the BL-group and 68.1 (SD 41.0) mm2 in the SPO-group (p = 0.49). No differences in the three predefined surgical outcomes between the three groups were found. Conclusion: For patients with lumbar spinal stenosis, the three different surgical techniques provided the same increase in dural sac area.

• Bråten, Lars Christian Haugli; Rolfsen, Mads Peder; Espeland, Ansgar; Wigemyr, Monica; Assmus, Jörg & Froholdt, Anne [Show all 28 contributors for this article] (2019). Efficacy of antibiotic treatment in patients with chronic low back pain and Modic changes (the AIM study): double blind, randomised, placebo controlled, multicentre trial. The BMJ. 367. doi: 10.1136/bmj.l5654. Full text in Research Archive Show summary

  Objective To assess the efficacy of three months of antibiotic treatment compared with placebo in patients with chronic low back pain, previous disc herniation, and vertebral endplate changes (Modic changes). Design Double blind, parallel group, placebo controlled, multicentre trial. Setting Hospital outpatient clinics at six hospitals in Norway. Participants 180 patients with chronic low back pain, previous disc herniation, and type 1 (n=118) or type 2 (n=62) Modic changes enrolled from June 2015 to September 2017. Interventions Patients were randomised to three months of oral treatment with either 750 mg amoxicillin or placebo three times daily. The allocation sequence was concealed by using a computer generated number on the prescription. Main outcome measures The primary outcome was the Roland-Morris Disability Questionnaire (RMDQ) score (range 0-24) at one year follow-up in the intention to treat population. The minimal clinically important between group difference in mean RMDQ score was predefined as 4. Results In the primary analysis of the total cohort at one year, the difference in the mean RMDQ score between the amoxicillin group and the placebo group was −1.6 (95% confidence interval −3.1 to 0.0, P=0.04). In the secondary analysis, the difference in the mean RMDQ score between the groups was −2.3 (−4.2 to−0.4, P=0.02) for patients with type 1 Modic changes and −0.1 (−2.7 to 2.6, P=0.95) for patients with type 2 Modic changes. Fifty patients (56%) in the amoxicillin group experienced at least one drug related adverse event compared with 31 (34%) in the placebo group. Conclusions In this study on patients with chronic low back pain and Modic changes at the level of a previous disc herniation, three months of treatment with amoxicillin did not provide a clinically important benefit compared with placebo. Secondary analyses and sensitivity analyses supported this finding. Therefore, our results do not support the use of antibiotic treatment for chronic low back pain and Modic changes.

• Berg, Linda; Thoresen, Hanne; Neckelmann, Gesche F; Furunes, Håvard; Hellum, Christian & Espeland, Ansgar (2019). Facet arthropathy evaluation: CT or MRI? European Radiology. ISSN 0938-7994. 29(9), p. 4990–4998. doi: 10.1007/s00330-019-06047-5. Full text in Research Archive Show summary

  Objective To assess the reliability of lumbar facet arthropathy evaluation with computed tomography (CT) or magnetic resonance imaging (MRI) in patients with and without lumbar disc prosthesis and to estimate the reliability for individual CT and MRI findings indicating facet arthropathy. Methods Metal-artifact reducing CT and MRI protocols were performed at follow-up of 114 chronic back pain patients treated with (n = 66) or without (n = 48) lumbar disc prosthesis. Three experienced radiologists independently rated facet joint space narrowing, osteophyte/hypertrophy, erosions, subchondral cysts, and total grade facet arthropathy at each of the three lower lumbar levels on both CT and MRI, using Weishaupt et al’s rating system. CT and MRI examinations were randomly mixed and rated independently. Findings were dichotomized before analysis. Overall kappa and (due to low prevalence) prevalence- and bias-adjusted kappa were calculated to assess interobserver agreement. Results Interobserver agreement on total grade facet arthropathy was moderate at all levels with CT (kappa 0.47–0.48) and poor to fair with MRI (kappa 0.20–0.32). Mean prevalence- and bias-adjusted kappa was lower for osteophyte/hypertrophy versus other individual findings (CT 0.58 versus 0.79–0.86, MRI 0.35 versus 0.81–0.90), higher with CT versus MRI when rating osteophyte/hypertrophy (0.58 versus 0.35) and total grade facet arthropathy (0.54 versus 0.31), and generally similar at levels with versus levels without disc prosthesis. Conclusion Interobserver agreement on facet arthropathy was moderate with CT and better with CT than with MRI. Disc prosthesis did not influence agreement. A more reliable grading of facet arthropathy requires a more consistent evaluation of osteophytes/hypertrophy.

• Austevoll, Ivar Magne; Hermansen, Erland; Fagerland, Morten; Rekeland, Frode; Solberg, Tore & Storheim, Kjersti [Show all 12 contributors for this article] (2019). Decompression alone versus decompression with instrumental fusion the NORDSTEN degenerative spondylolisthesis trial (NORDSTEN-DS); study protocol for a randomized controlled trial. BMC Musculoskeletal Disorders. 20:7, p. 1–10. doi: 10.1186/s12891-018-2384-0. Full text in Research Archive Show summary

  Background: Fusion in addition to decompression has become the standard treatment for lumbar spinal stenosis with degenerative spondylolisthesis (DS). The evidence for performing fusion among these patients is conflicting and there is a need for further investigation through studies of high quality. The present protocol describes an ongoing study with the primary aim of comparing the outcome between decompression alone and decompression with instrumented fusion. The secondary aim is to investigate whether predictors can be used to choose the best treatment for an individual. The trial, named the NORDSTEN-DS trial, is one of three studies in the Norwegian Degenerative Spinal Stenosis (NORDSTEN) study. Methods: The NORDSTEN-DS trial is a block-randomized, controlled, multicenter, non-inferiority study with two parallel groups. The surgeons at the 15 participating hospitals decide whether a patient is eligible or not according to the inclusion and exclusion criteria. Participating patients are randomized to either a midline preserving decompression or a decompression followed by an instrumental fusion. Primary endpoint is the percentage of patients with an improvement in Oswestry Disability Index version 2.0 of more than 30% from baseline to 2-year follow-up. Secondary outcome measurements are the Zürich Claudication Questionnaire, Numeric Rating Scale for back and leg pain, Euroqol 5 dimensions questionnaire, Global perceived effect scale, complications and several radiological parameters. Analysis and interpretation of results will also be conducted after 5 and 10years. Conclusion: The NORDSTEN/DS trial has the potential to provide Level 1 evidence of whether decompression alone should be advocated as the preferred method or not. Further on the study will investigate whether predictors exist and if they can be used to make the appropriate choice for surgical treatment for this patient group. Trial registration: ClinicalTrials.gov Identifier: NCT02051374. First Posted: January 31, 2014. Last Update Posted: February 14, 2018.

• Hermansen, Erland; Myklebust, Tor Åge; Austevoll, Ivar Magne; Rekeland, Frode; Solberg, Tore & Storheim, Kjersti [Show all 11 contributors for this article] (2019). Clinical outcome after surgery for lumbar spinal stenosis in patients with insignificant lower extremity pain. A prospective cohort study from the Norwegian registry for spine surgery. BMC Musculoskeletal Disorders. 20:36, p. 1–8. doi: 10.1186/s12891-019-2407-5. Full text in Research Archive Show summary

  Background: Spinal stenosis is a clinical diagnosis in which the main symptom is pain radiating to the lower extremities, or neurogenic claudication. Radiological spinal stenosis is commonly observed in the population and it is debated whether patients with no lower extremity pain should be labelled as having spinal stenosis. However, these patients is found in the Norwegian Registry for Spine Surgery, the main object of the present study was to compare the clinical outcomes after decompressive surgery in patients with insignificant lower extremity pain, with those with more severe pain. Methods: This study is based on data from the Norwegian Registry for Spine Surgery (NORspine). Patients who had decompressive surgery in the period from 7/1–2007 to 11/3–2013 at 31 hospitals were included. The patients was divided into four groups based on preoperative Numeric Rating Scale (NRS)-score for lower extremity pain. Patients in group 1 had insignificant pain, group 2 had mild or moderate pain, group 3 severe pain and group 4 extremely severe pain. The primary outcome was change in the Oswestry Disability Index (ODI). Successfully treated patients were defined as patients reporting at least 30% reduction of baseline ODI, and the number of successfully treated patients in each group were recorded. Results: In total, 3181 patients were eligible; 154 patients in group 1; 753 in group 2; 1766 in group 3; and 528 in group 4. Group 1 had significantly less improvement from baseline in all the clinical scores 12months after surgery compared to the other groups. However, with a mean reduction of 8 ODI points and 56% of patients showing a reduction of at least 30% in their ODI score, the proportion of patients defined as successfully treated in group 1, was not significantly different from that of other groups. Conclusion: This national register study shows that patients with insignificant lower extremity pain had less improvement in primary and secondary outcome parameters from baseline to follow-up compared to patients with more severe lower extremity pain.

• Austevoll, Ivar Magne; Gjestad, Rolf; Grotle, Margreth; Solberg, Tore; Brox, Jens Ivar & Hermansen, Erland [Show all 10 contributors for this article] (2019). 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. BMC Musculoskeletal Disorders. 20:31, p. 1–15. doi: 10.1186/s12891-018-2386-y. Full text in Research Archive Show summary

  Background: Assessment of outcomes for spinal surgeries is challenging, and an ideal measurement that reflects all aspects of importance for the patients does not exist. Oswestry Disability Index (ODI), EuroQol (EQ-5D) and Numeric Rating Scales (NRS) for leg pain and for back pain are commonly used patients reported outcome measurements (PROMs). Reporting the proportion of individuals with an outcome of clinical importance is recommended. Knowledge of the ability of PROMs to identify clearly improved patients is essential. The purpose of this study was to search cut-off criteria for PROMs that best reflect an improvement considered by the patients to be of clinical importance. Methods: The Global Perceived Effect scale was utilized to evaluate a clinically important outcome 12 months after surgery. The cut-offs for the PROMs that most accurately distinguish those who reported ‘completely recovered’ or ‘much improved’ from those who reported ‘slightly improved’, unchanged’, ‘slightly worse’, ‘much worse’, or ‘worse than ever’ were estimated. For each PROM, we evaluated three candidate response parameters: the (raw) follow-up score, the (numerical) change score, and the percentage change score. Results: We analysed 3859 patients with Lumbar Spinal Stenosis [(LSS); mean age 66; female gender 50%] and 617 patients with Lumbar Degenerative Spondylolisthesis [(LDS); mean age 67; 72% female gender]. The accuracy of identifying ‘completely recovered’ and ‘much better’ patients was generally high, but lower for EQ-5D than for the other PROMs. For all PROMs the accuracy was lower for the change score than for the follow-up score and the percentage change score, especially among patients with low and high PROM scores at baseline. The optimal threshold for a clinically important outcome was ≤24 for ODI, ≥0.69 for EQ-5D, ≤3 for NRS leg pain, and ≤ 4 for NRS back pain, and, for the percentage change score, ≥30% for ODI, ≥40% for NRS leg pain, and ≥ 33% for NRS back pain. The estimated cut-offs were similar for LSS and for LDS. Conclusion: For estimating a ‘success’ rate assessed by a PROM, we recommend using the follow-up score or the percentage change score. These scores reflected a clinically important outcome better than the change score.

• Furunes, Håvard; Hellum, Christian; Espeland, Ansgar; Brox, Jens Ivar; Småstuen, Milada C & Berg, Linda [Show all 7 contributors for this article] (2018). Adjacent disc degeneration after lumbar total disc replacement or non-operative Treatment: A randomized study with eight-year follow-up. Spine. ISSN 0362-2436. 43(24), p. 1695–1703. doi: 10.1097/BRS.0000000000002712. Full text in Research Archive Show summary

  Study Design. A randomized controlled multicenter trial with 8-year follow-up. Objective. The aim of this study was to assess the long-term development of adjacent disc degeneration (ADD) after lumbar total disc replacement (TDR) or nonoperative treatment, and to analyze the association between ADD development and clinical outcome. Summary of Background Data. TDR was introduced as a motion-preserving alternative to spinal fusion, which has been reported to increase the risk of ADD. However, ADD may develop naturally regardless of any surgery, and no randomized study has assessed the long-term development of ADD after TDR versus nonoperative treatment. Methods. The study included 126 of the 173 patients with chronic low back pain (LBP) originally included in a randomized study comparing TDR with multidisciplinary rehabilitation. Magnetic resonance imaging (MRI) of the lumbar spine was performed before treatment and at 8-year follow-up. ADD was categorized as increased or not increased based on an evaluation of Modic changes, disc height reduction, disc contour, herniation size, nucleus pulposus signal, and posterior high intensity zones. We used a χ2 test or a Fisher exact test to compare crude proportions, and multiple linear regressions to analyze the association between increased ADD (yes/no) and change in Oswestry Disability Index (ODI) from pre-treatment to follow-up. Results. ADD increased (for at least one ADD variable) in 23 of 57 patients (40%) treated nonoperatively, and 29 of 69 patients (42%) treated with TDR (P = 0.86). We found no significant associations between ADD increase and the change in ODI. Conclusion. Increased ADD occurred with similar frequency after TDR and after nonoperative treatment, and was not related to the clinical outcome at 8-year follow-up.

• Storheim, Kjersti; Berg, Linda; Hellum, Christian; Gjertsen, Øivind; Neckelmann, Gesche F & Espeland, Ansgar [Show all 7 contributors for this article] (2017). Fat in the lumbar multifidus muscles - predictive value and change following disc prosthesis surgery and multidiciplinary rehabilitation in patients With chronic low back pain and degenerative disc: 2-year follow-up of a randomized trial. BMC Musculoskeletal Disorders. 18:145(1), p. 1–11. doi: 10.1186/s12891-017-1505-5. Full text in Research Archive Show summary

  Background: Evidence is lacking on whether fat infiltration in the multifidus muscles affects outcomes after total disc replacement (TDR) surgery and if it develops after surgery. The aims of this study were 1) to investigate whether pre-treatment multifidus muscle fat infiltration predicts outcome 2 years after treatment with TDR surgery or multidisciplinary rehabilitation, and 2) to compare changes in multifidus muscle fat infiltration from pre-treatment to 2-year follow-up between the two treatment groups. Methods: The study is secondary analysis of data from a trial with 2-year follow-up of patients with chronic low back pain (LBP) and degenerative disc randomized to TDR surgery or multidisciplinary rehabilitation. We analyzed (aim 1) patients with both magnetic resonance imaging (MRI) at pre-treatment and valid data on outcome measures at 2-year follow-up (predictor analysis), and (aim 2) patients with MRI at both pre-treatment and 2-year follow-up. Outcome measures were visual analogue scale (VAS) for LBP, Oswestry Disability Index (ODI), work status and muscle fat infiltration on MRI. Patients with pre-treatment MRI and 2-year outcome data on VAS for LBP (n = 144), ODI (n = 147), and work status (n = 137) were analyzed for prediction purposes. At 2-year follow-up, 126 patients had another MRI scan, and change in muscle fat infiltration was compared between the two treatment groups. Three radiologists visually quantified multifidus muscle fat in the three lower lumbar levels on MRI as <20% (grade 0), 20–50% (grade 1), or >50% (grade 2) of the muscle cross-section containing fat. Regression analysis and a mid-P exact test were carried out. Results: Grade 0 pre-treatment multifidus muscle fat predicted better clinical results at 2-year follow-up after TDR surgery (all outcomes) but not after rehabilitation. At 2-year follow-up, increased fat infiltration was more common in the surgery group (intention-to-treat p = 0.03, per protocol p = 0.08) where it was related to worse pain and ODI. Conclusions: Patients with less fat infiltration of multifidus muscles before TDR surgery had better outcomes at 2-year follow-up, but findings also indicated a negative influence of TDR surgery on back muscle morphology in some patients. The rehabilitation group maintained their muscular morphology and were unaffected by pre-treatment multifidus muscle fat.

• Hermansen, Erland; Austevoll, Ivar Magne; Romild, Ulla Kristina; Rekeland, Frode; Solberg, Tore & Storheim, Kjersti [Show all 11 contributors for this article] (2017). 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). BMC Musculoskeletal Disorders. 18:121, p. 1–7. doi: 10.1186/s12891-017-1491-7. Full text in Research Archive Show summary

  Background: There are several posterior decompression techniques for lumbar spinal stenosis (LSS). There is a trend towards performing less invasive surgical procedures, but no multicentre randomized controlled trials have evaluated the relative efficacy of these techniques at short and long-term. Method/design: A multicentre randomized controlled trial [the Spinal Stenosis Trial (SST) (part of the NORDSTEN study)] including 465 patients aged 18–80 years with neurogenic claudication or radiating pain and MRI findings indicating lumbar spinal stenosis without spondylolisthesis is performed to compare three posterior decompression techniques: unilateral laminotomy with crossover, bilateral laminotomy and spinous process osteotomy. The primary outcome is change in Oswestry Disability Index (ODI 2 years postoperatively). Secondary outcomes are change in EQ-5D, Zurich Claudication Questionnaire, and Numeric Rating Scale for leg-pain and back-pain. Also recorded were Global Perceived Effect score, complications, length of hospital stay, reoperation rate 2 years postoperatively, difference in recurrence of symptoms or postoperative instability, and MRI change in the dural sac area. Further, a 5 and 10 years follow-up is planned with the same outcome measures. Discussion: Newer and less invasive techniques are increasingly favoured in surgery for LSS. This trial will compare the clinical and radiological results of three different techniques, and may contribute to better clinical decision making in the surgical treatment of LSS.

• Furunes, Håvard; Hellum, Christian; Brox, Jens Ivar; Rossvoll, Ivar; Espeland, Ansgar & Berg, Linda [Show all 9 contributors for this article] (2017). Lumbar total disc replacement: predictors for long-term outcome. European spine journal. ISSN 0940-6719. 27(3), p. 709–718. doi: 10.1007/s00586-017-5375-1. Full text in Research Archive Show summary

  Purpose We aimed to identify patient characteristics associated with favourable long-term outcomes after lumbar total disc replacement (TDR). Methods We analysed a cohort of 82 patients with degenerative disc and chronic low back pain (LBP) who were treated with TDR and originally participated in a randomised trial comparing TDR and multidisciplinary rehabilitation. Potential predictors were measured at baseline, and the outcomes assessed 8 years after they received allocated treatment. Outcome measures were dichotomised according to whether the participants achieved a clinically important functional improvement (15 points or more on the Oswestry Disability Index, ODI) (primary outcome) and whether they were employed at 8-year follow-up (secondary outcome). Associations between potential predictors and outcomes were modelled using logistic regression. For the secondary outcome, the results were also organised in a prediction matrix and expressed as probabilities. Results For 71 patients treated with TDR according to protocol, the follow-up time was 8 years. For a subgroup of 11 patients randomised to rehabilitation who crossed over and received TDR, the median postoperative follow-up time was 72 (range 41–88) months. Of all assessed baseline variables, only presence of Modic changes (type 1 and/or 2) was statistically significantly associated with an improvement of ≥ 15 ODI points. The probability of employment at 8-year follow-up was 1% for patients with ≥ 1 year of sick leave, comorbidity, ODI ≥ 50 and ≤ 9 years of education prior to treatment, and 87% for patients with < 1 year of sick leave, no comorbidity, ODI < 50 and higher education. Conclusions Patients with Modic changes prior to the TDR surgery were more likely to report a clinically important functional improvement at long-term follow-up. Comorbidity, low level of education, long-term sick leave and high ODI score at baseline were associated with unemployment at long-term follow-up.

• Habiba, Samer; Nygaard, Øystein Petter; Brox, Jens Ivar; Hellum, Christian; Austevoll, Ivar Magne & Solberg, Tore (2017). Risk factors for surgical site infections among 1,772 patients operated on for lumbar disc herniation: a multicentre observational registry-based study. Acta Neurochirurgica. ISSN 0001-6268. 159(6), p. 1113–1118. doi: 10.1007/s00701-017-3184-2. Full text in Research Archive Show summary

  Background There are no previous studies evaluating risk factors for surgical site infections (SSIs) and the effectiveness of prophylactic antibiotic treatment (PAT), specifically for patients operated on for lumbar disc herniation. Method This observational multicentre study comprises a cohort of 1,772 consecutive patients operated on for lumbar disc herniation without laminectomy or fusion at 23 different surgical units in Norway. The patients were interviewed about SSIs according to a standardised questionnaire at 3 months’ follow-up. Results Three months after surgery, 2.3% of the patients had an SSI. Only no PAT (OR = 5.3, 95% CI = 2.2–12.7, p< 0.001) and longer duration of surgery than the mean time (68 min) (OR = 2.8, 95% CI = 1.2–6.6, p = 0.02) were identified as independent risk factors for SSI. Numbers needed to have PAT to avoid one SSI was 43. Conclusions In summary, this study clearly lends support to the use of PAT in surgery for lumbar disc herniation. Senior surgeons assisting inexperienced colleagues to avoid prolonged duration of surgery could also reduce the occurrence of SSI.

• Furunes, Håvard; Storheim, Kjersti; Brox, Jens Ivar; Johnsen, Lars Gunnar; Skouen, Jan Sture & Franssen, Eric [Show all 9 contributors for this article] (2017). Total disc replacement versus multidisciplinary rehabilitation in patients with chronic low back pain and degenerative discs: 8-year follow-up of a randomized controlled multicenter trial. The spine journal. ISSN 1529-9430. 17(10), p. 1480–1488. doi: 10.1016/j.spinee.2017.05.011. Full text in Research Archive Show summary

  Background Context Lumbar total disc replacement (TDR) is a treatment option for selected patients with chronic low back pain (LBP) that is non-responsive to conservative treatment. The long-term results of disc replacement compared with multidisciplinary rehabilitation (MDR) have not been reported previously. Purpose We aimed to assess the long-term relative efficacy of lumbar TDR compared with MDR. Design We undertook a multicenter randomized controlled trial at five university hospitals in Norway. Patient Sample The sample consisted of 173 patients aged 25–55 years with chronic LBP and localized degenerative changes in the lumbar intervertebral discs. Outcome Measures The primary outcome was self-reported physical function (Oswestry Disability Index [ODI]) at 8-year follow-up in the intention-to-treat population. Secondary outcomes included self-reported LBP (visual analogue scale [VAS]), quality of life (EuroQol [EQ-5D]), emotional distress (Hopkins Symptom Checklist [HSCL-25]), occupational status, patient satisfaction, drug use, complications, and additional back surgery. Methods Patients were randomly assigned to lumbar TDR or MDR. Self-reported outcome measures were collected 8 years after treatment. The study was powered to detect a difference of 10 ODI points between the groups. The study has not been funded by the industry. Results A total of 605 patients were screened for eligibility, of whom 173 were randomly assigned treatment. Seventy-seven patients (90%) randomized to surgery and 74 patients (85%) randomized to rehabilitation responded at 8-year follow-up. Mean improvement in the ODI was 20.0 points (95% confidence interval [CI] 16.4–23.6, p≤.0001) in the surgery group and 14.4 points (95% CI 10.7–18.1, p≤.0001) in the rehabilitation group. Mean difference between the groups at 8-year follow-up was 6.1 points (95% CI 1.2–11.0, p=.02). Mean difference in favor of surgery on secondary outcomes were 9.9 points on VAS (95% CI 0.6–19.2, p=.04) and 0.16 points on HSCL-25 (95% CI 0.01–0.32, p=.04). There were 18 patients (24%) in the surgery group and 4 patients (6%) in the rehabilitation group who reported full recovery (p=.002). There were no significant differences between the groups in EQ-5D, occupational status, satisfaction with care, or drug use. In the per protocol analysis, the mean difference between groups was 8.1 ODI points (95% CI 2.3–13.9, p=.01) in favor of surgery. Forty-three of 61 patients (70%) in the surgery group and 26 of 52 patients (50%) in the rehabilitation group had a clinically important improvement (15 ODI points or more) from baseline (p=.03). The proportion of patients with a clinically important deterioration (six ODI points or more) was not significantly different between the groups. Twenty-one patients (24%) randomized to rehabilitation had crossed over and had undergone back surgery since inclusion, whereas 12 patients (14%) randomized to surgery had undergone additional back surgery. One serious adverse event after disc replacement is registered (<1%). Conclusions Substantial long-term improvement can be expected after both disc replacement and MDR. The difference between groups is statistically significant in favor of surgery, but smaller than the prespecified clinically important difference of 10 ODI points that the study was designed to detect. Future research should aim to improve selection criteria for disc replacement and MDR.

• Austevoll, Ivar Magne; Gjestad, Rolf; Brox, Jens Ivar; Solberg, Tore; Storheim, Kjersti & Rekeland, Frode [Show all 9 contributors for this article] (2016). The effectiveness of decompression alone compared with additional fusion for lumbar spinal stenosis with degenerative spondylolisthesis: a pragmatic comparative non-inferiority observational study from the Norwegian Registry for Spine Surgery. European spine journal. ISSN 0940-6719. 26(2), p. 404–413. doi: 10.1007/s00586-016-4683-1. Full text in Research Archive Show summary

  Purpose To evaluate the effect of adding fusion to decompression in patients operated for lumbar spinal stenosis with a concomitant lumbar degenerative spondylolisthesis. Methods After propensity score matching, 260 patients operated with decompression and fusion and 260 patients operated with decompression alone were compared. Primary outcome measures were leg and back pain [Numeric Rating Scale (NRS), 0–10] and Oswestry Disability Index (ODI, 0–100) at 12 months. Results At 12-month follow-up, the fusion group rated their pain significantly lower than the decompression alone group [leg pain 3.0 and 3.6, respectively, mean difference −0.6, 95 % confidence interval (CI) −1.2 to −0.05, p = 0.03 and back pain 3.3 and 3.9, respectively, mean difference −0.6, 95 % CI −1.1 to −0.1, p = 0.02]. ODI was not significantly different between the groups (21.0 versus 23.3, mean difference −2.3, 95 % CI −5.8 to 1.1, p = 0.18). Seventy-four percent of the fusion group and 63 % of the decompression alone group achieved a clinically important improvement in back pain (difference in proportion of responders = 11 %, 95 % CI 2–20 %, p = 0.01), corresponding to a number needed to treat of 9 patients (95 % CI 5–50). There was no significant difference in responder rate for leg pain (74 and 67 %, respectively, difference 7 %, 95 % CI −1 to 16 %, p = 0.09) or for ODI (67 and 59 %, respectively, difference 8 %, 95 % CI 0–18 %, p = 0.06). The duration of surgery and hospital stay was longer for the fusion group (mean difference 68 min, 95 % CI 58–78, p < 0.01 and mean difference 4.2 days, 95 % CI 3.5–4.8, p < 0.01). Conclusion In the present non-inferiority study, we cannot conclude that decompression alone is as good as decompression with additional fusion. However, the small differences in the groups’ effect sizes suggest that a considerable number of patients can be treated with decompression alone. A challenge in future studies will be to find the best treatment option for each patient.

• Hermansen, Erland; Romild, Ulla Kristina; Austevoll, Ivar Magne; Solberg, Tore; Storheim, Kjersti & Brox, Jens Ivar [Show all 8 contributors for this article] (2016). Does surgical technique influence clinical outcome after lumbar spinal stenosis decompression? A comparative effectiveness study from the Norwegian Registry for Spine Surgery. European spine journal. ISSN 0940-6719. 26(2), p. 420–427. doi: 10.1007/s00586-016-4643-9. Full text in Research Archive
• Johnsen, Lars Gunnar; Hellum, Christian; Storheim, Kjersti; Nygaard, Øystein Petter; Brox, Jens Ivar & Rossvoll, Ivar [Show all 15 contributors for this article] (2014). Cost-effectiveness of total disc replacement versus multidisciplinary rehabilitation in patients with chronic low back pain: A norwegian multicenter RCT. Spine. ISSN 0362-2436. 39(1), p. 23–32. doi: 10.1097/BRS.0000000000000065. Full text in Research Archive Show summary

  Study Design. Randomized clinical trial with 2-year follow-up. Objective. To evaluate the cost-effectiveness of total disc replacement (TDR) versus multidisciplinary rehabilitation (MDR) in patients with chronic low back pain (CLBP). Summary of Background Data. The existing studies on CLBP report cost-effectiveness of fusion surgery versus disc replacement and fusion versus rehabilitation. This study evaluated the cost-effectiveness of TDR versus MDR. Methods. Between April 2004 and May 2007, 173 patients with CLBP (>1 yr) were randomized to TDR (n = 86) or MDR (n = 87). Treatment effects (Euro Qol 5D [EQ-5D] and Short Form 6D [SF-6D]) and relevant direct and indirect costs at 6 weeks and at 3, 6, 12, and 24 months after treatment were assessed. Gain in quality-adjusted life years (QALYs) after 2 years was estimated. Cost-effectiveness was expressed as an incremental cost-effectiveness ratio. Results. The mean QALYs gained (standard deviation) using EQ-5D was 1.29 (0.53) in the TDR group and 0.95 (0.52) in the MDR group, a significant difference of 0.34 (95% confidence interval 0.18–0.50). The mean total cost per patient in the TDR group was €87,622 (58,351) compared with €74,116 (58,237) in the MDR group, which was not significantly different (95% confidence interval: −4041 to 31,755). The incremental cost-effectiveness ratio for the TDR procedure varied from €39,748 using EQ-5D (TDR cost-effective) to €128,328 using SF-6D (TDR not cost-effective). The dropout rate was 20% (15% TDR group, 24% MDR group). Five patients moved from the MDR to the TDR group, whereas 9 patients randomized to TDR declined surgery. Using per-protocol analysis instead of intention-to-treat analysis indicated that TDR was not cost-effective, irrespective of the use of EQ-5D or SF-6D. Conclusion. In this study, TDR was cost-effective compared with MDR after 2 years when using EQ-5D for assessing QALYs gained and a willingness to pay of €74,600 (kr500,000/QALY). TDR was not cost-effective when SF-6D was used; therefore, our results should be interpreted with caution. Longer follow-up is needed to accurately assess the cost-effectiveness of TDR.

• Wilkens, Philip; Scheel, Inger B.; Grundnes, Oliver; Hellum, Christian & Storheim, Kjersti (2013). Prognostic Factors of Prolonged Disability in Patients With Chronic Low Back Pain and Lumbar Degeneration in Primary Care. Spine. ISSN 0362-2436. 38(1), p. 65–74. doi: 10.1097/BRS.0b013e318263bb7b. Full text in Research Archive
• Berg, Linda; Hellum, Christian; Gjertsen, Øivind; Neckelmann, Gesche F; Johnsen, Lars Gunnar & Storheim, Kjersti [Show all 9 contributors for this article] (2013). Do more MRI findings imply worse disability or more intense low back pain? A cross-sectional study of candidates for lumbar disc prosthesis. Skeletal Radiology. ISSN 0364-2348. 42(11), p. 1593–1602. doi: 10.1007/s00256-013-1700-x. Full text in Research Archive
• Johnsen, Lars Gunnar; Brinckmann, Paul; Hellum, Christian; Rossvoll, Ivar & Leivseth, Gunnar (2013). Segmental mobility, disc height and patientreported outcomes after surgery for degenerative disc disease A PROSPECTIVE RANDOMISED TRIAL COMPARING DISC REPLACEMENT AND MULTIDISCIPLINARY REHABILITATION. The Bone & Joint Journal. ISSN 2049-4394. 95B(1), p. 81–89. doi: 10.1302/0301-620X.95B1.29829. Full text in Research Archive
• Johnsen, Lars Gunnar; Hellum, Christian; Nygaard, Øystein Petter; Storheim, Kjersti; Brox, Jens Ivar & Rossvoll, Ivar [Show all 8 contributors for this article] (2013). Comparison of the SF6D, the EQ5D, and the oswestry disability index in patients with chronic low back pain and degenerative disc disease. BMC Musculoskeletal Disorders. 14:148. doi: 10.1186/1471-2474-14-148. Full text in Research Archive Show summary

  Background: The need for cost effectiveness analyses in randomized controlled trials that compare treatment options is increasing. The selection of the optimal utility measure is important, and a central question is whether the two most commonly used indexes - the EuroQuol 5D (EQ5D) and the Short Form 6D (SF6D) – can be used interchangeably. The aim of the present study was to compare change scores of the EQ5D and SF6D utility indexes in terms of some important measurement properties. The psychometric properties of the two utility indexes were compared to a disease-specific instrument, the Oswestry Disability Index (ODI), in the setting of a randomized controlled trial for degenerative disc disease. Methods: In a randomized controlled multicentre trial, 172 patients who had experienced low back pain for an average of 6 years were randomized to either treatment with an intensive back rehabilitation program or surgery to insert disc prostheses. Patients filled out the ODI, EQ5D, and SF-36 at baseline and two-year follow up. The utility indexes was compared with respect to measurement error, structural validity, criterion validity, responsiveness, and interpretability according to the COSMIN taxonomy. Results: At follow up, 113 patients had change score values for all three instruments. The SF6D had better similarity with the disease-specific instrument (ODI) regarding sensitivity, specificity, and responsiveness. Measurement error was lower for the SF6D (0.056) compared to the EQ5D (0.155). The minimal important change score value was 0.031 for SF6D and 0.173 for EQ5D. The minimal detectable change score value at a 95% confidence level were 0.157 for SF6D and 0.429 for EQ5D, and the difference in mean change score values (SD) between them was 0.23 (0.29) and so exceeded the clinical significant change score value for both instruments. Analysis of psychometric properties indicated that the indexes are unidimensional when considered separately, but that they do not exactly measure the same underlying construct. Conclusions: This study indicates that the difference in important measurement properties between EQ5D and SF6D is too large to consider them interchangeable. Since the similarity with the “gold standard” (the disease-specific instrument) was quite different, this could indicate that the choice of index should be determined by the diagnosis.

• Berg, Linda; Neckelmann, Gesche F; Gjertsen, Øivind; Hellum, Christian; Johnsen, Lars Gunnar & Eide, Geir Egil [Show all 7 contributors for this article] (2012). Reliability of MRI findings in candidates for lumbar disc prosthesis. Neuroradiology. ISSN 0028-3940. 54(7), p. 699–707. doi: 10.1007/s00234-011-0963-y. Full text in Research Archive Show summary

  Introduction: Limited reliability data exist for localised magnetic resonance imaging (MRI) findings relevant to planning of treatment with lumbar disc prosthesis and later outcomes. We assessed the reliability of such findings in chronic low back pain patients who were accepted candidates for disc prosthesis. Methods: On pretreatment MRI of 170 patients (mean age 41 years; 88 women), three experienced radiologists independently rated Modic changes, disc findings and facet arthropathy at L3/L4, L4/L5 and L5/S1. Two radiologists rerated 126 examinations. For each MRI finding at each disc level, agreement was analysed using the kappa statistic and differences in prevalence across observers using a fixed effects model. Results: All findings at L3/L4 and facet arthropathy at L5/S1 had a mean prevalence <10% across observers and were not further analysed, ensuring interpretable kappa values. Overall interobserver agreement was generally moderate or good (kappa 0.40–0.77) at L4–S1 for Modic changes, nucleus pulposus signal, disc height (subjective and measured), posterior high-intensity zone (HIZ) and disc contour, and fair (kappa 0.24) at L4/L5 for facet arthropathy. Posterior HIZ at L5/S1 and severely reduced subjective disc height at L4/L5 differed up to threefold in prevalence between observers (p< 0.0001). Intraobserver agreement was mostly good or very good (kappa 0.60–1.00). Conclusion: In candidates for disc prosthesis, mostly moderate interobserver agreement is expected for localised MRI findings.

• Hellum, Christian; Johnsen, Lars Gunnar; Gjertsen, Øivind; Berg, Linda; Neckelmann, Gesche F & Grundnes, Oliver [Show all 10 contributors for this article] (2012). Predictors of outcome after surgery with disc prosthesis and rehabilitation in patients with chronic low back pain and degenerative disc: 2-year follow-up. European spine journal. ISSN 0940-6719. 21(4), p. 681–690. doi: 10.1007/s00586-011-2145-3. Full text in Research Archive
• Hellum, Christian; Berg, Linda; Gjertsen, Øivind; Johnsen, Lars Gunnar; Neckelmann, Gesche F & Storheim, Kjersti [Show all 9 contributors for this article] (2012). Adjacent level degeneration and facet arthropathy after disc prosthesis surgery or rehabilitation in patients with chronic low back pain and degenerative disc. Spine. ISSN 0362-2436. 37(25), p. 2063–2073. doi: 10.1097/BRS.0b013e318263cc46. Full text in Research Archive
• Berg, Linda; Gjertsen, Øivind; Hellum, Christian; Neckelmann, Gesche F; Johnsen, Lars Gunnar & Eide, Geir Egil [Show all 7 contributors for this article] (2012). Reliability of change in lumbar MRI findings over time in patients with and without disc prosthesis-comparing two different image evaluation methods. Skeletal Radiology. ISSN 0364-2348. 41(12), p. 1547–1557. doi: 10.1007/s00256-012-1394-5. Full text in Research Archive
• Hellum, Christian; Johnsen, Lars Gunnar; Storheim, Kjersti; Nygaard, Øystein Petter; Brox, Jens Ivar & Rossvoll, Ivar [Show all 9 contributors for this article] (2011). Surgery with disc prosthesis versus rehabilitation in patients with lowback pain and degenerative disc: two year follow-up of randomised study. BMJ. British Medical Journal. ISSN 0959-8146. 342. doi: 10.1136/bmj.d2786. Full text in Research Archive
• Wilkens, Philip; Scheel, Inger B; Grundnes, Oliver; Hellum, Christian & Storheim, Kjersti (2010). Effect of Glucosamine on Pain-Related Disability in Patients With Chronic Low Back Pain and Degenerative Lumbar Osteoarthritis A Randomized Controlled Trial. Journal of the American Medical Association (JAMA). ISSN 0098-7484. 304(1), p. 45–52. doi: 10.1001/jama.2010.893. Full text in Research Archive

View all works in NVA

• Åkerstedt, Josefin; Wänman, Johan; Banitalebi, Hasan; Myklebust, Tor Åge; Weber, Clemens & Storheim, Kjersti [Show all 10 contributors for this article] (2025). Change in Lumbar Lordosis After Decompressive Surgery in Lumbar Spinal Stenosis Patients and Associations With Patient-Related Outcomes Two Years After Surgery: Radiologic and Clinical Results From the NORDSTEN Spinal Stenosis Trial. Spine. ISSN 0362-2436. 50(1), p. 40–45. doi: 10.1097/BRS.0000000000005263. Full text in Research Archive
• Hermansen, Erland; Indrekvam, Kari; Franssen, Eric; Myklebust, Tor Åge; Austevoll, Ivar Magne & Hellum, Christian [Show all 16 contributors for this article] (2025). Correction to: ISSLS Prize in Clinical Science 2025: A randomized trial on three different minimally invasive decompression techniques for lumbar spinal stenosis. Five years follow-up from the NORDSTEN-SST (European Spine Journal, (2024), 10.1007/s00586-024-08514-0). European spine journal. ISSN 0940-6719. 34(5), p. 2044–2045. doi: 10.1007/s00586-024-08561-7. Full text in Research Archive
• Austevoll, Ivar Magne; Hellum, Christian & Försth, Peter (2024). Letter to the Editor Regarding the Paper of Shukla and Colleagues on Laminectomy with Fusion is Associated with Greater Functional Improvement Compared with Laminectomy Alone for the Treatment of Degenerative Lumbar Spondylolisthesis. Spine. ISSN 0362-2436. 49(2), p. E17–E17. doi: 10.1097/BRS.0000000000004800. Full text in Research Archive
• Seip, Andreas Ottersen; Solberg, Tore; Brox, Jens Ivar; Hermansen, Erland; Fagerland, Morten & Weber, Clemens [Show all 14 contributors for this article] (2024). P293. Surgeons’ selection of the right patient for fusion surgery for degenerative spondylolisthesis. The spine journal. ISSN 1529-9430. 24(9), p. S207–S207. doi: 10.1016/j.spinee.2024.06.416. Full text in Research Archive
• Rolfsen, Mads Peder; Gammelsrud, Karianne Wiger; Espeland, Ansgar; Bråten, Lars Christian Haugli; Mjønes, Sverre Markussen & Austevoll, Ivar Magne [Show all 15 contributors for this article] (2024). Bacterial growth in patients with low back pain and Modic changes: protocol of a multicentre, case-control biopsy study. BMJ Open. 14(5), p. 1–7. doi: 10.1136/bmjopen-2023-082244. Full text in Research Archive Show summary

  Introduction Bacterial infection and Modic changes (MCs) as causes of low back pain (LBP) are debated. Results diverged between two randomised controlled trials examining the effect of amoxicillin with and without clavulanic acid versus placebo on patients with chronic LBP (cLBP) and MCs. Previous biopsy studies have been criticised with regard to methods, few patients and controls, and insufficient measures to minimise perioperative contamination. In this study, we minimise contamination risk, include a control group and optimise statistical power. The main aim is to compare bacterial growth between patients with and without MCs. Methods and analysis This multicentre, case–control study examines disc and vertebral body biopsies of patients with cLBP. Cases have MCs at the level of tissue sampling, controls do not. Previously operated patients are included as a subgroup. Tissue is sampled before antibiotic prophylaxis with separate instruments. We will apply microbiological methods and histology on biopsies, and predefine criteria for significant bacterial growth, possible contamination and no growth. Microbiologists, surgeons and pathologist are blinded to allocation of case or control. Primary analysis assesses significant growth in MC1 versus controls and MC2 versus controls separately. Bacterial disc growth in previously operated patients, patients with large MCs and growth from the vertebral body in the fusion group are all considered exploratory analyses. Ethics and dissemination The Regional Committees for Medical and Health Research Ethics in Norway (REC South East, reference number 2015/697) has approved the study. Study participation requires written informed consent. The study is registered at ClinicalTrials.gov (NCT03406624). Results will be disseminated in peer-reviewed journals, scientific conferences and patient fora.

• Banitalebi, Hasan; Hermansen, Erland; Hellum, Christian; Storheim, Kjersti; Indrekvam, Kari & Espeland, Ansgar [Show all 12 contributors for this article] (2023). Association between preoperative fatty infiltration of the paraspinal muscles and persistent leg pain after surgery for LSS. Full text in Research Archive Show summary

  Introduction: Fatty infiltration of the paraspinal muscles may have a role in clinical outcomes after decompression surgery for lumbar spinal stenosis (LSS). The purpose of this study was to evaluate the prognostic value of preoperative fatty infiltration of the paraspinal muscles assessed by MRI in postoperative pain or disability in LSS. Materials and Methods: Prospective imaging and clinical data from the NORwegian Degenerative spondylolisthesis and spinal STENosis- spinal stenosis trial (NORDSTEN-SST) study were used. A musculoskeletal radiologist evaluated preoperative lumbar MRI examination of 300 patients with LSS scheduled for decompression surgery. Only axial T2-weighted images covering the paraspinal and the psoas muscles bilaterally were considered. Fatty infiltration of the paraspinal muscles was assessed by a muscle fat index (MFI). For this assessment, signal intensity of the multifidus and the erector spinae at the most stenotic level of lumbar spine was divided by the signal intensity of the psoas major muscle at the same level and side of spine. Pain and disability two years after surgery were assessed using patient-reported outcome measures including the Oswestry disability index (ODI, scores 0 to 100), the Zurich claudication questionnaire (ZCQ) for symptoms severity (scores 1 to 5) and function (scores 1 to 4), and numeric rating scales (NRSs) for leg and back pain (scores 1 to 10). Multivariate linear and logistic regression analyses were used to assess the relationship between the MFI and the patient-reported clinical outcomes. In the logistic regression models, odds ratios (OR) and 95% confidence intervals (CIs) were calculated for associations between the MFI and ≥ 30% improvement of the postoperative outcomes (dichotomised into yes or no). Results: After excluding 57 patients because axial images did not cover the muscles bilaterally, images from 243 patients were evaluated. Mean age of the patients was 66.6 (±8.5) years and 119 were females (49%). Preoperative MFI and postoperative leg pain were significantly associated, both when leg pain was analysed as a continuous parameter (coefficient: -3.2, 95% CI: -5.6 to -0.8, p = 0.009) and dichotomised score (OR 62.8, 95% CI: 4.8 to 817.8, p = 0.002). These findings suggested that increased fatty infiltration in the paraspinal muscles is associated with higher risk of persistent leg pain after decompression surgery for LSS. The associations between the MFI and the other outcome measures were not statistically significant. Conclusion: Increased preoperative fatty infiltration in the paraspinal muscles on MRI was associated with persistent leg pain two years after decompression surgery for LSS. This preoperative MRI finding may be useful as a prognostic factor in patients with LSS undergoing decompression surgery.

• Banitalebi, Hasan; Hermansen, Erland; Hellum, Christian; Storheim, Kjersti; Espeland, Ansgar & Indrekvam, Kari [Show all 10 contributors for this article] (2023). Fatty Infiltration of the Paraspinal Muscles Is Associated with Postoperative Leg Pain in Lumbar Spinal Stenosis. Full text in Research Archive Show summary

  Purpose To evaluate the prognostic value of MRI-assessed preoperative fatty infiltration of the paraspinal muscles in postoperative pain or disability in lumbar spinal stenosis (LSS). Methods Prospective imaging and clinical data from the NORwegian Degenerative spondylolisthesis and spinal STENosis- spinal stenosis trial (NORDSTEN-SST) study were used. A musculoskeletal radiologist evaluated preoperative lumbar MRI examination of 300 patients with LSS scheduled for decompression surgery. Only axial T2-weighted images covering the paraspinal and the psoas muscles bilaterally were considered. Fatty infiltration of the paraspinal muscles was assessed by a muscle fat index (MFI). For this assessment, signal intensity of the multifidus and the erector spinae at the most stenotic level of lumbar spine was divided by the signal intensity of the psoas major muscle at the same level and side of spine. Pain and disability two years after surgery were assessed using patient-reported outcome measures including the Oswestry disability index (ODI, scores 0 to 100), the Zurich claudication questionnaire (ZCQ) for symptoms severity (scores 1 to 5) and function (scores 1 to 4), and numeric rating scales (NRSs) for leg and back pain (scores 1 to 10). Multivariate linear and logistic regression analyses were used to assess the relationship between the MFI and the patient-reported clinical outcomes. In the logistic regression models, odds ratios (OR) and 95% confidence intervals (CIs) were calculated for associations between the MFI and ≥ 30% improvement of the postoperative outcomes (dichotomised into yes or no). Results After excluding 57 patients because axial images did not cover the muscles bilaterally, images from 243 patients were evaluated. Mean age of the patients was 66.6 (±8.5) years and 119 were females (49%). Preoperative MFI and postoperative leg pain were significantly associated, both when leg pain was analysed as a continuous parameter (coefficient: -3.2, 95% CI: -5.6 to -0.8, p = 0.009) and dichotomised score (OR 62.8, 95% CI: 4.8 to 817.8, p = 0.002). These findings suggested that increased fatty infiltration in the paraspinal muscles is associated with higher risk of persistent leg pain after decompression surgery for LSS. The associations between the MFI and the other outcome measures were not statistically significant. Conclusion Increased preoperative fatty infiltration in the paraspinal muscles on MRI was associated with persistent leg pain two years after decompression surgery for LSS. This preoperative MRI finding may be useful as a prognostic factor in patients with LSS undergoing decompression surgery.

• Austevoll, Ivar Magne; Storheim, Kjersti & Hellum, Christian (2021). Surgery with or without Fusion for Lumbar Spondylolisthesis. Reply. New England Journal of Medicine. ISSN 0028-4793. 385(19), p. 1823–1824. doi: 10.1056/NEJMc2114488. Full text in Research Archive
• Ahmed, Mohamed; Hermansen, Erland; Austevoll, Ivar Magne; Hellum, Christian & Indrekvam, Kari (2012). Norsk spinal stenose studie. Full text in Research Archive
• Austevoll, Ivar Magne; Indrekvam, Kari; Müller, Oliver; Brox, Jens Ivar; Hellum, Christian & Hermansen, Erland [Show all 10 contributors for this article] (2012). Degenerativ pondylolisthese: Er det nødvendig å gjøre fiksasjon i tillegg til dekompresjon? Presentasjon av planlagt norsk multisenterstudie. Full text in Research Archive

View all works in NVA