Decompression with or without Fusion in Degenerative Lumbar Spondylolisthesis.

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 (decompression-alone 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 intention-to-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 decompression-alone group than in the fusion group. (NORDSTEN-DS ClinicalTrials.gov number, NCT02051374.).

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.

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.

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.

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.

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.

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.

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.

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.

The Tibial Tuberosity-Trochlear Groove Distance Can either Increase or Decrease during Adolescent Growth.

Increased Tibial Tuberosity-Trochlear Groove (TT-TG) distance is a risk factor for recurrent lateral patella dislocations (RLPD). Population-based cross-sectional studies on healthy subjects demonstrate that the TT-TG increases gradually during growth until skeletal maturity, but changes in the TT-TG distance during adolescence in patients with RLPD on an individual basis have not been previously investigated. This study aimed to measure changes in TT-TG distance during skeletal maturity. The TT-TG of 13 consecutive patients with open physes (mean age 13 years) with RLPD was measured on MRI at baseline and three years later. The change in TT-TG distance over the three-year period was measured. The mean change in TT-TG distance from the baseline to the three-year follow-up increased overall (2.9 mm, 95% Confidence Interval (CI) 2.1-3.7). However, the TT-TG distance could either increase or decrease during final growth. Our results suggest that the TT-TG distance in patients suffering from RLPD may either decrease or increase individually during the growth spurt. This contradicts the current concept that the TT-TG distance increases gradually during growth.

The Influence of Spinous Process Union on Clinical Outcomes After Spinous Process Osteotomy for Lumbar Spinal Stenosis After 2 Years: A Secondary Analysis From the NORDSTEN-Study.

BACKGROUND: Lumbar spinal stenosis is a prevalent and increasingly important cause of low back pain, leg pain, and walking impairment. Minimally invasive decompressive techniques such as spinous process (SP) osteotomy have become more common in recent years. The main aim of this study was to investigate the proportion of complete SP union and whether complete radiological healing after the osteotomy is associated with superior clinical outcome after 2 years. METHODS: In this retrospective cohort study, 149 patients were included from the Spinal Stenosis Trial, a part of the NORwegian Degenerative spondylolisthesis and spinal STENosis study. Computed tomography imaging was performed 2 years postoperatively. The number of osteotomies and the number of SP unions were recorded. Patients were divided into groups based on the degree of union: nonunion, partial union, and complete union. Rate of success (>30% improvement in Oswestry Disability Index [ODI]) and mean change in ODI were the primary outcome measures. We compared the differences between baseline and follow-up between the Degree of Union groups. RESULTS: The study included 102 of 149 eligible patients. Ten patients (9.8%) were classified as having nonunion, 15 (14.7%) as having partial union, and 77 (75.5%) as having complete union. Of the 155 osteotomies, there were 122 classified as union (77%). The success rate was 74%, with no influence of SP union. The mean change in the ODI was -20.1 (95% CI -37.0, 14.2) with no influence of SP union. CONCLUSIONS: We found no influence of SP union, classified by computed tomography, on clinical outcome 2 years after SP osteotomy in patients with lumbar spinal stenosis. CLINICAL RELEVANCE: Supplying useful information about SPO to assist surgeons in the choice of decompressive technique.

Change in Lumbar Lordosis after Decompressive Surgery in Lumbar Spinal Stenosis Patients and Associations with Patient Related Outcomes 2 Years after Surgery. Radiological and Clinical Results from the NORDSTEN Spinal Stenosis Trial.

STUDY DESIGN: A prospective cohort study. OBJECTIVE: The aim was to investigate changes in lumbar lordosis (LL) and its association to changes in patient reported outcome measures (PROMs) after decompressive surgery for lumbar spinal stenosis (LSS). SUMMARY OF BACKGROUND: Few studies have addressed change in LL after decompression surgery for LSS in relation to outcomes. METHOD: Pre- and postoperative data from 310 patients having standing x-ray both before and 2 years after surgery were included. The patients were grouped based on the change in LL preoperatively to 2 years after surgery; group 1: <5 degrees (n=196), group 2: ≥5 <10 degrees (n=55) or group 3: ≥10 degrees (n=59) of change in LL. The changes in function, disability and pain were assessed by the Oswestry Disability Index (ODI), Numeric Rating Scale (NRS), and the Zurich claudication questionnaire (ZCQ). The three groups were compared regarding baseline variables using the ANOVA test for continuous variables and the chi-square test for categorical variables. The groups were further compared with a likelihood ratio test in relation to changes in PROMs 2 year after surgery and outcomes were adjusted for respective baseline PROMs, age, sex, smoking, BMI, Schizas and Pfirrmann scores. RESULTS: LL was significantly changed at group level 2 years after surgery with a mean difference of 2.2 (SD 9.4) degrees ( P =0.001). The three LL change groups did not show any significant differences in patient characteristics, function, disability, and pain at baseline. The two groups with a change of more than 5 degrees in LL 2 year after surgery (group 2 and 3) had significantly greater improvements in ODI ( P =0.022) and ZCQ function ( P =0.016) in the adjusted analyses, but was not significant for back and leg pain. CONCLUSION: Changed LL after decompressive surgery for LSS was associated with improved ODI and physical function.

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.

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.

Is Repeated Preoperative Magnetic Resonance Imaging Necessary Before Planned Decompressive Surgery for Lumbar Spinal Stenosis?

BACKGROUND: Currently, there are different routines in Norwegian hospitals regarding how recent magnetic resonance imaging (MRI) of the lumbar spine should be performed before surgery. Patients with lumbar spinal stenosis from the Norwegian degenerative spondylolisthesis and spinal stenosis study, who had 2 preoperative MRIs performed within the year before surgery, were included. The aim of the present study was to evaluate the utility of repeated preoperative MRI for patients undergoing decompressive spine surgery for degenerative spinal stenosis. METHODS: For all included patients, the changes between the 2 preoperative MRIs were investigated for disc degeneration (Pfirrmann's classification), foraminal stenosis (Lee's classification), spondylolisthesis, and central canal stenosis (Schizas score and dural sac cross-sectional area). RESULTS: A total of 65 patients (78 levels) were included. Thirty-seven patients were women, and the mean age was 67 (range 48-79) years. Schizas score showed a clinically meaningful change of ±2 or 3 grades in 5 levels, and dural sac cross- sectional area was reduced in 47 levels with a mean change of -2.3 mm2. Three levels had a clinically relevant change in grade of foraminal stenosis of ±2. For disc degeneration, 53 of the levels had no change, and the rest of the levels had a change of ±1 grade. Increased spondylolisthesis was measured at 21 levels, and the mean slip was <2 mm. Also, 4 levels had >2 mm slip. CONCLUSION: For patients undergoing surgery for lumbar spinal stenosis, repeated MRI within the year before planned surgery showed few significant changes in common radiological parameters. The benefit for the surgeon of repeat MRI is therefore limited.

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.

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 mm 2 (SD: 21.1). Postoperatively the area increased to a mean area of 120.6 mm 2 (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.

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.

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.

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.

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.

Explainable Artificial Intelligence for Human-Machine Interaction in Brain Tumor Localization.

Primary malignancies in adult brains are globally fatal. Computer vision, especially recent developments in artificial intelligence (AI), have created opportunities to automatically characterize and diagnose tumor lesions in the brain. AI approaches have provided scores of unprecedented accuracy in different image analysis tasks, including differentiating tumor-containing brains from healthy brains. AI models, however, perform as a black box, concealing the rational interpretations that are an essential step towards translating AI imaging tools into clinical routine. An explainable AI approach aims to visualize the high-level features of trained models or integrate into the training process. This study aims to evaluate the performance of selected deep-learning algorithms on localizing tumor lesions and distinguishing the lesion from healthy regions in magnetic resonance imaging contrasts. Despite a significant correlation between classification and lesion localization accuracy (R = 0.46, p = 0.005), the known AI algorithms, examined in this study, classify some tumor brains based on other non-relevant features. The results suggest that explainable AI approaches can develop an intuition for model interpretability and may play an important role in the performance evaluation of deep learning models. Developing explainable AI approaches will be an essential tool to improve human-machine interactions and assist in the selection of optimal training methods.