Comparison of Patients Operated for Lumbar Spinal Stenosis with and without Spondylolisthesis - A Secondary Analysis of the NORDSTEN Trials.

STUDY DESIGN: Observational cohort study (secondary analysis of two randomized trials). OBJECTIVE: 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 two years after surgery differ between lumbar spinal stenosis patients with and without spondylolisthesis. SUMMARY OF BACKGROUND DATA: Lumbar spinal stenosis is a degenerative condition of the spine, which appears with or without degenerative spondylolisthesis often presenting similar signs and symptoms. METHOD: This study is a secondary analysis of two randomized trials on patients with lumbar spinal stenosis with and without spondylolisthesis conducted at 16 public Norwegian hospitals. Disability, function, back pain, leg pain, quality of life, complication and reoperation rates up to two years after surgery were compared between the two cohorts. RESULTS: A total of 704 patients were included in this study, 267 patients with spondylolisthesis (median age 67.0 years [IQR 61.0-72.0]; 68.7% female) and 437 patients without spondylolisthesis (median age 68.0 years IQR 62.0-73.0]; 52.9% female). In the linear mixed model analysis there were no significant differences in disability, function, back pain, leg pain and quality of life scores between the two cohorts of patient with and without spondylolisthesis before surgery or at two years follow-up. The complication rate was 22.9% in patients with spondylolisthesis and 12.1% in patients without spondylolisthesis (P<0.001). There were no significant differences in reoperation rates. CONCLUSION: In patients with lumbar spinal stenosis the symptom burden before surgery and the clinical outcome up to two years after surgery were similar independently of a concomitant spondylolisthesis.

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.

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.

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.

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.

Do patients with lumbar spinal stenosis benefit from decompression of levels with adjacent moderate stenosis? A prospective cohort study from the NORDSTEN study.

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.

The Norwegian degenerative spondylolisthesis and spinal stenosis (NORDSTEN) study: study overview, organization structure and study population.

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. TRIAL REGISTRATION: ClinicalTrials.gov; NCT02007083 10/12/2013, NCT02051374 31/01/2014 and NCT03562936 20/06/2018.

Is the presence of foraminal stenosis associated with outcome in lumbar spinal stenosis patients treated with posterior microsurgical decompression.

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. TRIAL REGISTRATION: The study is registered at ClinicalTrials.gov (22.11.2013) under the identifier NCT02007083.

Surgery in degenerative spondylolisthesis: does fusion improve outcome in subgroups? A secondary analysis from a randomized trial (NORDSTEN trial).

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.

The association between preoperative MRI findings and clinical improvement in patients included in the NORDSTEN spinal stenosis trial.

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.

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

Importance: Operations for lumbar spinal stenosis is the most often performed surgical procedure in the adult lumbar spine. This study reports the clinical outcome of the 3 most commonly used minimally invasive posterior decompression techniques. Objective: To compare the effectiveness of 3 minimally invasive posterior decompression techniques for lumbar spinal stenosis. Design, Setting, and Participants: This randomized clinical trial used a parallel group design and included patients with symptomatic and radiologically verified lumbar spinal stenosis without degenerative spondylolisthesis. Patients were enrolled between February 2014 and October 2018 at the orthopedic and neurosurgical departments of 16 Norwegian public hospitals. Statistical analysis was performed in the period from May to June 2021. Interventions: Patients were randomized to undergo 1 of the 3 minimally invasive posterior decompression techniques: unilateral laminotomy with crossover, bilateral laminotomy, and spinous process osteotomy. Main Outcomes and Measures: Primary outcome was change in disability measured with Oswestry Disability Index (ODI; range 0-100), presented as mean change from baseline to 2-year follow-up and proportions of patients classified as success (>30% reduction in ODI). Secondary outcomes were mean change in quality of life, disease-specific symptom severity measured with Zurich Claudication Questionnaire (ZCQ), back pain and leg pain on a 10-point numeric rating score (NRS), patient perceived benefit of the surgical procedure, duration of the surgical procedure, blood loss, perioperative complications, number of reoperations, and length of hospital stay. Results: In total, 437 patients were included with a median (IQR) age of 68 (62-73) years and 230 men (53%). Of the included patients, 146 were randomized to unilateral laminotomy with crossover, 142 to bilateral laminotomy, and 149 to spinous process osteotomy. The unilateral laminotomy with crossover group had a mean change of -17.9 ODI points (95% CI, -20.8 to -14.9), the bilateral laminotomy group had a mean change of -19.7 ODI points (95% CI, -22.7 to -16.8), and the spinous process osteotomy group had a mean change of -19.9 ODI points (95% CI, -22.8 to -17.0). There were no significant differences in primary or secondary outcomes among the 3 surgical procedures, except a longer duration of the surgical procedure in the bilateral laminotomy group. Conclusions and Relevance: No differences in clinical outcomes or complication rates were found among the 3 minimally invasive posterior decompression techniques used to treat patients with lumbar spinal stenosis. Trial Registration: ClinicalTrials.gov Identifier: NCT02007083.

Reliability of preoperative MRI findings in patients with lumbar spinal stenosis.

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. TRIAL REGISTRATION: www.ClinicalTrials.gov identifier: NCT02007083 , registered December 2013.

Clinical and MRI findings in lumbar spinal stenosis: baseline data from the NORDSTEN study.

PURPOSE: The aim was to describe magnetic resonance imaging findings in patients planned for lumbar spinal stenosis surgery. Further, to describe possible associations between MRI findings 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 findings were evaluated before surgery: morphological (Schizas) and quantitative (cross-sectional area) grade of stenosis, disk degeneration (Pfirrmann), facet joint tropism and fatty infiltration of the multifidus muscle. Patients were dichotomized into a moderate or severe category for each radiological parameter classification. A multivariable linear regression analysis was performed to investigate the association between MRI findings 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%, Pfirrmann (4 + 5) 58.1%, tropism (≥ 15°) 11.9%, degeneration of multifidus muscle (2-4) 83.7%. Regression coefficients indicated minimal changes in severity of symptoms when comparing the groups with moderate and severe MRI findings. Only gender had a significant and clinically relevant association with ODI score. CONCLUSION: In this cross-sectional study, the majority of the patients had MRI findings classified as severe LSS changes, but the findings 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 findings. TRIAL REGISTRATION: www. CLINICALTRIALS: gov identifier: NCT02007083, registered December 2013.

Comparative Effectiveness of Microdecompression Alone vs Decompression Plus Instrumented Fusion in Lumbar Degenerative Spondylolisthesis.

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.

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.

PURPOSE: To investigate changes in dural sac area after three different posterior decompression techniques in patients undergoing surgery for lumbar spinal stenosis. 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. CLINICAL TRIAL REGISTRATION: The study is registered at ClinicalTrials.gov reference on November 22th 2013 under the identifier NCT02007083.

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.

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.

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.

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 12 months 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.

Decompression alone versus decompression with instrumental fusion the NORDSTEN degenerative spondylolisthesis trial (NORDSTEN-DS); study protocol for a randomized controlled trial.

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 10 years. 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.

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).

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. TRIAL REGISTRATION: ClinicalTrials.gov reference: NCT02007083 (November 22, 2013).

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

INTRODUCTION: The aim of this study was to compare the clinical outcome of spinal process osteotomy with two other midline-retaining methods, bilateral laminotomy and unilateral laminotomy with crossover, among patients undergoing surgery for lumbar spinal stenosis. METHODS: This cohort study was based on data from the Norwegian Registry for Spine Surgery (NORspine). Patients were operated on between 2009 and 2013 at 31 Norwegian hospitals. The patients completed questionnaires at admission for surgery, and after 3 and 12 months. The Oswestry Disability Index (ODI) was the primary outcome. Secondary outcomes were duration of surgery and hospital stay, Numeric Rating Scale (NRS) for back pain and leg pain, and EQ-5D and EQ-VAS. The patients were classified into one of three treatment groups according to the surgery they had received, and a propensity score was utilized to minimize bias. The three treatment groups were divided into subgroups based on Propensity Scores, and the statistical analyses were performed with and within the Propensity Score stratified subgroups. RESULTS: 103 patients had spinal process osteotomy, 966 patients had bilateral laminotomy, and 462 patients had unilateral laminotomy with crossover. Baseline clinical scores were similar in the three groups. There were no differences in improvement after 3 and 12 months between treatment groups. At 12 months, mean ODI improvement was 15.2 (SD 16.7) after spinous process osteotomy, 16.9 (SD 17.0) after bilateral laminotomy, and 16.7 (SD 16.9) after unilateral laminotomy with crossover. There were no differences in the secondary clinical outcomes or complication rates. Mean duration of surgery was greatest for spinal process osteotomy (p < 0.05). Length of stay was 2.1 days (SD 2.1) in the bilateral laminotomy group, 3.5 (SD 2.4) days for unilateral laminotomy, and 6.9 days (SD 4.1) for spinous process osteotomy group (p < 0.05). CONCLUSION: In a propensity scored matched cohort, there were no differences in the clinical outcome 12 months after surgery for lumbar spinal stenosis performed using the three different posterior decompression techniques. Bilateral laminotomy had shortest duration of surgery and shortest length of hospital stay. Surgical technique does not seem to affect clinical outcome after three different midline-retaining posterior decompression techniques.