Effect of the preoperative assessment of the anteroposterior diameters of the spinal canal and dural area on the efficacy of oblique lumbar interbody fusion in patients with lumbar spinal stenosis.

OBJECTIVE: The purpose of this study was to quantify the degree of lumbar spinal stenosis by assessing the anterior and posterior vertebral canal diameter and dural area, determine the sensitivity of the anterior and posterior spinal canal diameter, dural area and dural occupying rate in predicting the postoperative efficacy of oblique lumbar interbody fusion (OLIF) for patients with single-stage lumbar spinal stenosis, and identify the corresponding indicators suggesting that OLIF surgery should not be performed. METHODS: In a retrospective analysis of patients who had previously undergone OLIF surgery in our hospital, we included a total of 104 patients with lumbar spinal stenosis who had previously undergone single-stage surgery in our hospital. Three independent observers were employed to measure the anterior and posterior diameter of the spinal canal (AD, mm), dural area (CSA, mm2), the spinal canal area (SCA, mm2), and the ratio of the dural area to the spinal canal area (DM, %) at the disc level with the most severe stenosis on MRI. According to the values of AD and CSA in preoperative MRI, patients were divided into three groups: A, B, and C (Group A: AD > 12 and 100 < CSA ≤ 130, group B: Except A and C, group C: AD ≤ 10 and CSA ≤ 75). Preoperative and postoperative clinical outcome scores (Japanese Orthopaedic Association [JOA] score, VAS score, modified Macnab standard) of 104 patients were statistically. RESULTS: There were significant differences in the preoperative and postoperative clinical correlation scores among the mild, moderate and severe lumbar spinal stenosis groups. The improvement rate of the post treatment JOA score, the difference between the preoperative and postoperative VAS score, and the modified Macnab standard were compared pairwise. There was no statistical significance in the improvement rate of the post treatment JOA score, the difference between the preoperative and postoperative VAS score, and the modified Macnab standard between Group A and Group B (P = 0.125, P = 0.620, P = 0.803). There were statistically significant differences between Group A and Group C and between Group B and Group C in the improvement rate of the JOA score, the difference in the pre- and postoperative VAS score, and the modified Macnab standard. The anterior and posterior vertebral canal diameter and dural area are sensitive predictors of the postoperative efficacy of OLIF surgery for single-stage lumbar spinal stenosis. Moreover, when the anterior and posterior vertebral canal diameter was less than 6.545 mm and the dural area was less than 34.43 mm2, the postoperative effect of OLIF surgery was poor. CONCLUSIONS: All the patients with mild, moderate, and severe lumbar spinal stenosis achieved curative effects after OLIF surgery. Patients with mild and moderate lumbar spinal stenosis had better curative effects, and there was no significant difference between them, while patients with severe lumbar spinal stenosis had poor curative effects. Both the anteroposterior diameter of the spinal canal and the dural area of the spinal canal were sensitive in predicting the curative effect of OLIF surgery for single-stage lumbar spinal stenosis. When the anterior and posterior vertebral canal diameter was less than 6.545 mm and the dural area was less than 34.43 mm2, the postoperative effect of OLIF surgery was poor.

A decision tree analysis to predict clinical outcome of minimally invasive lumbar decompression surgery for lumbar spinal stenosis with and without coexisting spondylolisthesis and scoliosis.

BACKGROUND CONTEXT: Implementing machine learning techniques, such as decision trees, known as prediction models that use logical construction diagrams, are rarely used to predict clinical outcomes. PURPOSE: To develop a clinical prediction rule to predict clinical outcomes in patients who undergo minimally invasive lumbar decompression surgery for lumbar spinal stenosis with and without coexisting spondylolisthesis and scoliosis using a decision tree model. STUDY DESIGN/SETTING: A retrospective analysis of prospectively collected data. PATIENT SAMPLE: This study included 331 patients who underwent minimally invasive surgery for lumbar spinal stenosis and were followed up for ≥2 years at 1 institution. OUTCOME MEASURES: Self-report measures: The Japanese Orthopedic Association (JOA) scores and low back pain (LBP)/leg pain/leg numbness visual analog scale (VAS) scores. Physiologic measures: Standing sagittal spinopelvic alignment, computed tomography, and magnetic resonance imaging results. METHODS: Low achievement in clinical outcomes were defined as the postoperative JOA score at the 2-year follow-up <25 points. Univariate and multiple logistic regression analysis and chi-square automatic interaction detection (CHAID) were used for analysis. RESULTS: The CHAID model for JOA score <25 points showed spontaneous numbness/pain as the first decision node. For the presence of spontaneous numbness/pain, sagittal vertical axis ≥70 mm was selected as the second decision node. Then lateral wedging, ≥6° and pelvic incidence minus lumbar lordosis (PI-LL) ≥30° followed as the third decision node. For the absence of spontaneous numbness/pain, sex and lateral olisthesis, ≥3mm and American Society of Anesthesiologists physical status classification system score were selected as the second and third decision nodes. The sensitivity, specificity, and the positive predictive value of this CHAID model was 65.1, 69.8, and 64.7% respectively. CONCLUSIONS: The CHAID model incorporating basic information and functional and radiologic factors is useful for predicting surgical outcomes.

Axial loading during supine MRI for improved assessment of lumbar spine: comparison with standing MRI.

BACKGROUND: There are no studies comparing the morphologic changes of lumbar spines between supine axial-loaded and 90° standing magnetic resonance imaging (MRI) examinations of patients with spinal stenosis. PURPOSE: To determine whether axial-loaded MRI using a compression device demonstrated similar morphology of intervertebral disc, dural sac, and spinal curvature as those detected by 90° standing MRI in individuals with suspected spinal stenosis. MATERIAL AND METHODS: A total of 54 individuals suspected of having spinal stenosis underwent both axial-loaded and standing MRI studies. The outcome measures included seven radiologic parameters of the lumbar spine: measures of the intervertebral disc (i.e. cross-sectional area [DA], disc height [DH], and anteroposterior distance [DAP]), dural sac (cross-sectional area [DCSA]), spinal curvature (i.e. lumbar lordosis [LL] and L1-L3-L5 angle [LA]), and total lumbar spine height (LH). RESULTS: For agreement between the two methods, intraclass correlation coefficient (ICC) ≥ 0.8 was found for all seven radiologic parameters. Supine axial-loaded MRI underestimated LL but remained correlated (ICC = 0.83) with standing MRI. Minor differences between the two methods (≤5.0%) were observed in DA, DCSA, DAP, LA, and LH, while a major difference was observed in LL (8.1%). CONCLUSION: Using a compression device with the conventional supine MRI to simulate weight-bearing on the lumbar spine generated MRI morphology, which was strongly correlated with those from a standing MRI.

The glasgow lumbar spinal stenosis scale: an individualised measurement formula for the radiological assessment of lumbar spinal stenosis.

BACKGROUND: Lumbar spinal stenosis (LSS) is a common and important spinal surgical problem. Currently there is no universally accepted quantitative approach to the radiological measurement of LSS. LSS can be described qualitatively with reference to facet and ligamentous hypertrophy, lack of perineural or intraforaminal fat, and reduced CSF around the cauda equina. Quantitative descriptions do exist e.g., lumbar canal antero-posterior diameter, but these are unidimensional and do not consider normal variation in anatomy. We propose a universal and individualised measurement system for the quantitative radiological assessment of lumbar spinal stenosis. METHODS: A retrospective case series of patients who had undergone surgery for symptomatic lumbar spinal stenosis over a 3 year period. Pre-operative lumbar spine MRI were analysed. Each patient had the degree of lumbar canal stenosis quantified using our novel approach. RESULTS: Our novel formula for the quantitative radiological assessment of lumbar spinal stenosis is two dimensional, repeatable and presented as a percentage, to correct for the individual patient. The surface area of the lumbar spinal canal at the level of stenosis is measured in mm2 plus the adjacent 2 levels which are then averaged. The calculation then becomes (A-S/A) x 100 = R, where S is the canal surface area at the stenosed level in mm2, A is the average canal surface area of the two levels adjacent to the level of interest and R is the relative degree of lumbar spinal canal stenosis expressed as a percentage. Measurements are calculated using axial T2 weighted images. CONCLUSIONS: This novel quantitative measurement formula for the radiological assessment of lumbar canal spinal stenosis is quick and simple to calculate and most importantly adjusts for the individual patient's normal or degenerative anatomy. This new measurement tool will need validation against specific clinical and operative criteria in the future.

Radiological and functional assessment in patients with lumbar spinal stenosis.

BACKGROUND: Although patients with lumbar spinal stenosis (LSS) may have impaired postural control, current diagnosis of LSS depends mainly on clinical manifestation and radiological assessment, while functional assessment of postural balance remains less investigated. This study thus correlated radiological assessment via MR imaging with functional assessment using foam posturography in LSS patients. METHODS: Forty-seven LSS patients aged 50-85 years were enrolled. All patients received subjective outcome measures first, followed by plain radiography of whole spine and lumbosacral spine, MR imaging, and foam posturography under four conditions. Then, these results were analyzed using stepwise multiple regression analysis. Another 47 age- and sex-matched healthy controls also underwent foam posturography for comparison. RESULTS: The LSS group revealed significant increases in the sway area of foam posturography than the control group regardless of various conditions. Advanced age, poor walking endurance, and neural compression at the L2/3 level on MR images were significantly correlated with the characteristic parameters of foam posturography (p < 0.05). In contrast, subjectively reported pain and plain radiography did not correlate with posturographic results (p > 0.05). CONCLUSIONS: Patients with LSS who exhibit less severe symptoms do not ensure normal postural balance. Functional assessment (foam posturography) on postural balance significantly correlated with radiological assessment (MR imaging) in LSS patients. The use of foam posturography may help assess postural control in LSS patients. It takes a short time and costs less, and would be practical to make this a routine examination in LSS patients.

Cerebrospinal fluid signal loss sign: assessment of a new radiological sign in lumbar spinal stenosis.

PURPOSE: Sedimentation sign was reported to have high sensitivity and specificity for diagnosis of lumbar spinal stenosis (LSS). We aimed to determine cerebrospinal fluid signal loss (CSFSL) at the intervertebral disc levels in the sagittal plane using a numerical scoring system and to evaluate the diagnostic value of this method in differential diagnosis of LSS and non-specific low back pain (LBP) and compare it with SS. MATERIALS AND METHODS: We included consecutive patients between 50 and 80 years old, with lumbar spinal MRI examination in our institution. These patients were divided into two groups as LSS and LBP, according to symptoms and radiological findings. CSFSL sign was evaluated for both groups by two radiologists independently, using MR images. Sensitivity and specificity of both signs were calculated. RESULTS: A total of 406 patients (98 LSS and 308 non-specific LBP) were included. SS and CSFSL sign had a sensitivity of 90.8% and 82.7% and specificity of 75.4% and 84.1% in the whole cohort, respectively. When patients were grouped by dural sac cross-sectional areas (CSA), sensitivity and specificity of SS were 100% and 4.4%, 87.5% and 31.8%, and 41.7% and 76%, respectively, and sensitivity and specificity of CSFSL sign were 95.7% and 11.1%, 75% and 77.3%, and 16.7 and 92% for severe (CSA < 80 mm2), moderate (CSA: 80-100 mm2), mild (CSA: 100-120 mm2) radiologic stenosis, respectively. In moderate stenosis, accuracies of SS and CSFSL sign were 76.3% and 55.3%, respectively. CONCLUSION: CSFSL sign might be used to distinguish LSS from LBP and unlike SS it is successful in moderate stenosis.

Percutaneous spinal endoscopy with unilateral interlaminar approach to perform bilateral decompression for central lumbar spinal stenosis: radiographic and clinical assessment.

BACKGROUND: Recently, a percutaneous spinal endoscopy unilateral posterior interlaminar approach to perform bilateral decompression has been proposed for use in treatment of lumbar spinal stenosis, As a development and supplement to traditional surgery, its advantages regarding therapeutic effects and prognosis, such as minor soft tissue damage, little intraoperative blood loss, and a quick return to daily life. However, there are few analyses of this surgery with a follow-up of more than 1 year,we conducted this study in order to quantitatively investigate radiographic and clinical efficacies of this surgery for central lumbar spinal stenosis. MATERIALS AND METHODS: Forty-six patients with central lumbar spinal stenosis were enrolled from January 2017 to July 2018. The visual analog scale (VAS) for back pain and leg pain, Oswestry disability index (ODI), modified MacNab criteria were used to evaluate clinical efficiency at preoperative and postoperative time points. The intervertebral height index (IHI), cross-sectional area of the spinal canal (CSAC), calibrated disc signal (CDS) and spinal stability were examined to assess radiographic decompression efficiency via magnetic resonance imaging and X-ray at preoperative and postoperative time points. RESULTS: The VAS score for lower back pain and leg pain improved from 7.50 ± 0.78 to 1.70 ± 0.66 and from 7.30 ± 0.79 to 1.74 ± 0.68, respectively, and the ODI improved from 72.35 ± 8.15 to 16.15 ± 4.51. In terms of modified MacNab criteria, 91.3% of the patients achieved good or excellent outcomes. Furthermore, significant changes after surgery were observed for the percentage of CSAC, increasing from 125.3 ± 53.9 to 201.4 ± 78 mm2; however, no significant differences were observed for the remaining measurement indicators. CONCLUSIONS: The clinical and radiographic efficacies of this surgery for central lumbar spinal stenosis were good in short-term follow-up, and this surgery did not cause meaningful changes in IHI, CDS, and spine stability in short-term follow-up. The effect of long-term follow-up needs further investigation.

Functional Assessment of Lumbar Nerve Roots Using Coronal-plane Single-shot Turbo Spin-echo Diffusion Tensor Imaging.

We investigated the usefulness of diffusion tensor imaging using single-shot turbo spin-echo sequence (TSE-DTI) in detecting the responsible nerve root by multipoint measurements of fractional anisotropy (FA) values. Five patients with bilateral lumbar spinal stenosis showing unilateral neurological symptoms were examined using TSE-DTI. In the spinal canal, FA values in the symptomatic side were lower than those in the asymptomatic side. TSE-DTI using multipoint measurements of FA values can differentiate the responsible lumbar nerve root.

Predictability of the effects of epidural injection in lumbar spinal stenosis by assessment of lumbar MRI scans.

BACKGROUND: Numerous classification systems have been proposed to interpret lumbar MRI scans. The clinical impact of the measured parameters remains unclear. To evaluate the clinical significance of imaging results in patients with multisegmental degenerative pathologies, treating specialists can perform image-guided local injections to target defined areas such as the epidural space. OBJECTIVE: The aim of this retrospective study was to evaluate the correlation between lumbar spinal stenosis measurements obtained by MRI and improvement obtained through local epidural injection. METHODS: In this retrospective study various measurement and classification systems for lumbar spinal stenosis were applied to MRI scans of 100 patients with this pathological condition. The reported effect of epidural bupivacaine/triamcinolone injections at the site was recorded in these patients and a comparative analysis performed. RESULTS: MRI features assessed in this study did not show any relevant correlation with reported pain relief after epidural injection in patients with chronic lumbar stenosis, with the exception of posterior disc height with a weak Kendall's tau of -0.187 (p= 0.009). CONCLUSIONS: Although MRI is crucial for evaluating lumbar spinal stenosis, it cannot replace but is rather complementary to a good patient history and clinical examination or the results of local diagnostic injections.

Assessment of degenerative cervical stenosis on T2-weighted MR imaging: sensitivity to change and reliability of mid-sagittal and axial plane metrics.

STUDY DESIGN: A retrospective cross-sectional study. OBJECTIVE: To assess the sensitivity to change and reliability of various mid-sagittal and axial plane metrics in the assessment of patients with single-level degenerative cervical stenosis on T2-weighted MR imaging. SETTING: A diagnostic MR imaging facility in Sydney (Australia). METHODS: We retrospectively reviewed T2-weighted MR images of 85 consecutive patients (48 M and 37 F) with single-level degenerative cervical stenosis. Canal compromise and cord compression were evaluated using three mid-sagittal plane metrics (M1, M2, and M3) and two axial plane metrics (M4 and M5), at the level of stenosis and nonstenotic cephalad and caudal levels (controls). Sensitivity to change (SC) for each metric was evaluated as the percentage deviation of the measured value from the estimated normal value based on cephalad and caudal controls. Reliability for each metric was evaluated using intraclass correlation coefficients. RESULTS: Degenerative cervical stenosis showed a bimodal distribution peaking at C5-6 (n = 32) and C3-4 (n = 29) levels. The changes in the canal and cord geometry along the rostrocaudal axis were inconsistent. Across all individual subjects (reflecting a range of stenosis severity), M3 (-32.87% ± 10.60%) was more sensitive to change compared with M1 (16.64% ± 16.48%) and M2 (-23.95% ± 11.12%). Similarly, M4 (-24.62% ± 12.17%) was more sensitive to change compared with M5 (-6.71% ± 11.08%). The level of reliability was "moderate" to "excellent" for mid-sagittal plane measurements, and "poor" to "excellent" for axial plane measurements. CONCLUSION: Changes in canal dimensions in the mid-sagittal plane and cord shape in the axial plane are sensitive indicators of degenerative cervical stenosis on T2-weighted MR images.

Assessment of spinal cord motion as a new diagnostic MRI-parameter in cervical spinal canal stenosis: study protocol on a prospective longitudinal trial.

BACKGROUND: Increased spinal cord motion has been proven to be a relevant finding within spinal canal stenosis disclosed by phase-contrast MRI (PC-MRI). Adapted PC-MRI is a suitable and reliable method within the well deliberated setting. As the decision between conservative and operative treatment can be challenging in some cases, further diagnostic marker would facilitate the diagnostic process. We hypothesize that increased spinal cord motion will correlate to clinical course and functional impairment and will contribute as a new diagnostic marker. METHODS: A monocentric, prospective longitudinal observational trial on cervical spinal canal stenosis will be conducted at the University Medical Center Freiburg. Patients (n = 130) with relevant cervical spinal canal stenosis, being defined by at least contact to the spinal cord, will be included. Also, we will examine a control group of healthy volunteers (n = 20) as proof-of-principle. We will observe two openly assigned branches of participants undergoing conservative and surgical decompressive treatment (based on current German Guidelines) over a time course of 12 month, including a total of 4 visits. We will conduct a broad assessment of clinical parameters, standard scores and gradings, electrophysiological measurements, standard MRI, and adapted functional PC-MRI of spinal cord motion. Primary endpoint is the evaluation of an expected negative correlation of absolute spinal cord displacement to clinical impairment. Secondary endpoints are the evaluation of positive correlation of increased absolute spinal cord displacement to prolonged evoked potentials, prediction of clinical course by absolute spinal cord displacement, and demonstration of normalized spinal cord motion after decompressive surgery. DISCUSSION: With the use of adapted, non-invasive PC-MRI as a quantitative method for assessment of spinal cord motion, further objective diagnostic information can be gained, that might improve the therapeutic decision-making process. This study will offer the needed data in order to establish PC-MRI on spinal cord motion within the diagnostic work-up of patients suffering from spinal canal stenosis. TRIAL REGISTRATION: German Clinical Trials Register, ID: DRKS00012962 , Register date 2018/01/17.

Practice Variation Among Surgeons Treating Lumbar Spinal Stenosis in a Single Institution.

STUDY DESIGN: A retrospective study. OBJECTIVE: The aim of this study was to examine practice variation in the treatment of lumbar spinal stenosis and identify targets for reducing variation. SUMMARY OF BACKGROUND DATA: Lumbar spinal stenosis is a degenerative condition susceptible to practice variation. Reducing variation aims to improve quality, increase safety, and lower costs. Establishing differences in surgeons' practices from a single institution can help identify personalized variation. METHODS: We identified adult patients first diagnosed with lumbar spinal stenosis between 2003 and 2015 in three hospitals of the same institution with ICD-9 codes.We extracted number of office visits, imaging procedures, injections, electromyographies (EMGs), and surgery within the first year after diagnosis; physical therapy within the first 3 months after diagnosis. Multivariable logistic regression was used to identify factors associated with surgery. The coefficient of variation (CV) was calculated to compare the variation in practice. RESULTS: The 10,858 patients we included had an average of 2.5 visits (±1.9), 1.5 imaging procedures (±2.0), 0.03 EMGs (±0.22), and 0.16 injections (±0.53); 36% had at least one surgical procedure and 32% had physical therapy as part of their care. The CV was smallest for number of visits (19%) and largest for EMG (140%).Male sex [odds ratio (OR): 1.23, P < 0.001], seeing an additional surgeon (OR: 2.82, P < 0.001), and having an additional spine diagnosis (OR: 3.71, P < 0.001) were independently associated with surgery. Visiting an orthopedic clinic (OR: 0.46, P < 0.001) was independently associated with less surgical interventions than visiting a neurosurgical clinic. CONCLUSION: There is widespread variation in the entire spectrum of diagnosis and therapy for lumbar spinal stenosis among surgeons in the same institution. Male gender, seeing an additional surgeon, having an additional spine diagnosis, and visiting a neurosurgery clinic were independently associated with increased surgical intervention. The main target we identified for decreasing variability was the use of diagnostic EMG. LEVEL OF EVIDENCE: 3.

Medium-Term Outcome and CT Assessment of Lateral Foraminotomy at the Lumbosacral Junction in Dogs with Degenerative Lumbosacral Stenosis.

OBJECTIVE: This article aims to report the medium-term clinical outcome and assess persistence of enlargement of the lumbosacral lateral intervertebral neurovascular foramen using computed tomography (CT) volumetric analysis in dogs following lateral foraminotomy. MATERIALS: Six dogs that underwent lumbosacral lateral foraminotomy on one or both sides were evaluated with CT prior to, immediately postoperatively (n = 2) and at 12 to 44 months of follow-up. Five out of six dogs had successful clinical outcomes with alleviation of pain and increased levels of activity, according to subjective assessment. Immediate postoperative CT volumetric analysis of the lateral intervertebral neurovascular foramina in two dogs indicated a 650 to 800% increase in volume in extension achieved by foraminotomy (four foramens). At subsequent follow-up, bone regrowth had occurred with reduction in foraminal volume, though in both dogs foraminal volume remained higher than preoperative values. Follow-up CT at a median of 24 months postoperatively indicated a mean 335% increase in volume of the lumbosacral lateral intervertebral neurovascular foramina in extension compared with the preoperative foraminal volume. The follow-up volume was substantially greater than the presurgical volume in four out of six dogs. CLINICAL SIGNIFICANCE: In this limited case series, lateral foraminotomy achieved persistent enlargement of the lumbosacral lateral intervertebral neurovascular foramen in the medium term, but osseous regrowth at the site was demonstrated which may limit the effectiveness of lateral foraminotomy in the longer term. One of two working dogs had recurrent clinical signs that necessitated further surgery.

Cost-effectiveness of posterior lumbar interbody fusion in the Japanese universal health insurance system.

BACKGROUND: Globally, the cost-effectiveness of spinal surgery is becoming increasingly important. However, these data are limited to a few countries. The purpose of our study was to examine the cost/quality adjusted life year (cost/QALY) gained for posterior lumbar interbody fusion (PLIF) in the Japanese universal health insurance system. METHODS: Fifty five patients underwent PLIF for lumbar degenerative spinal canal stenosis between July 2013 and September 2015 was included. Effectiveness was measured using Euro QOL 5-dimension (EQ-5D), Short-Form 8 physical component summary (PCS), and visual analog scale (VAS). The cost was calculated from the perspective of the public healthcare payer. Effectiveness and cost were measured one year after surgery. QALYs were calculated by multiplying the utility value (EQ-5D) and life years. Only direct costs were included on the basis of actual reimbursements. Cost/QALY at a 5-year time horizon with a 2% discount rate was estimated. Sensitivity analysis was performed by varying the time horizon (2 years or 10 years). The exchange rate was defined as US $1 to Japanese 100 yen. RESULTS: Mean total cost one year after surgery was ï¿¥2,802,900 ($28029). Operative cost was ï¿¥1,779,700 ($17797). Mean gained score was 0.22 in EQ-5D, 10.3 in PCS, and -44 in VAS. Cost/QALY was ï¿¥2,697,500 ($26975). Sensitivity analysis demonstrated that cost/QALY at a 10-year time horizon was ï¿¥1,428,300 ($14283) and that cost/QALY at a 2-year time horizon was ï¿¥6,435,400 ($64354). CONCLUSIONS: Clinical outcomes after PLIF improved beyond minimum clinical improvement difference. Cost/QALY was below the widely-accepted benchmark (cost/QALY < $50000). PLIF could be regarded as cost-effective interventions.

Radiographic Assessment on Magnetic Resonance Imaging after Percutaneous Endoscopic Lumbar Foraminotomy.

Percutaneous endoscopic lumbar foraminotomy (ELF) is a novel minimally invasive technique used to treat lumbar foraminal stenosis. However, the validity of foraminal decompression based on quantitative assessment using magnetic resonance imaging (MRI) has not yet been established. The objective of this study was to investigate the radiographic efficiency of ELF using MRI. Radiographic changes of neuroforamen were measured based on pre- and postoperative MRI findings. Images were blindly analyzed by two observers for foraminal stenosis grade and foraminal dimensions. The intraclass correlation coefficient (ICC) and k statistic were calculated to determine interobserver agreement. Thirty-five patients with 40 neuroforamen were evaluated. The mean visual analog scale (VAS) score improved from 8.4 to 2.1, and the mean Oswestry disability index (ODI) improved from 65.9 to 19.2. Overall, 91.4% of the patients achieved good or excellent outcomes. The mean grade of foraminal stenosis significantly improved from 2.63 to 0.68. There were significant increases in the mean foraminal area (FA) from 50.05 to 92.03 mm2, in mean foraminal height (FH) from 11.36 to 13.47 mm, in mean superior foraminal width (SFW) from 6.43 to 9.27 mm, and in mean middle foraminal width (MFW) from 1.47 to 78 mm (P < 0.001). Interobserver agreements for preoperative and postoperative measurements were good to excellent with the exception of SFW. In conclusion, foraminal dimensions and grades of foraminal stenosis significantly improved after ELF. These findings may enhance the clinical relevance of endoscopic lumbar foraminal decompression.

Is multidetector computed tomography comparable to magnetic resonance imaging for assessment of lumbar foraminal stenosis?

Background Both multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) are used for assessment of lumbar foraminal stenosis (LFS). Therefore, it is relevant to assess agreement between these imaging modalities. Purpose To determine intermodality, inter-, and intra-observer agreement for assessment of LFS on MDCT and MRI. Material and Methods A total of 120 foramina in 20 patients who visited our institution in January and February 2014 were evaluated by six radiologists with different levels of experience. Radiologists evaluated presence and severity of LFS on sagittal CT and MR images according to a previously published LFS grading system. Intermodality agreement was analyzed by using weighted kappa statistics, while inter- and intra-observer agreement were analyzed by using intraclass correlation coefficients (ICCs) and kappa statistics. Results Overall intermodality agreement was moderate to good (kappa, 0.478-0.765). In particular, two professors and one fellow tended to overestimate the degree of LFS on CT compared with MRI. For inter-observer agreement of all six observers, ICCs indicated excellent agreement for both CT (0.774) and MRI (0.771), while Fleiss' kappa values showed moderate agreement for CT (0.482) and MRI (0.575). There was better agreement between professors and fellows compared with residents. For intra-observer agreement, ICCs indicated excellent agreement, while kappa values showed good to excellent agreement for both CT and MRI. Conclusion MDCT was comparable to MRI for diagnosis and assessment of LFS, especially for experienced observers. However, there was a tendency to overestimate the degree of LFS on MDCT compared with MRI.

Radiographic assessment of degenerative lumbar spinal stenosis: is MRI superior to CT?

OBJECTIVE: To determine the reliability and dependability of magnetic resonance imaging (MRI) and computerized tomography (CT) in the assessment of lumbar spinal stenosis and correlate the qualitative assessment to both a quantitative assessment and functional outcome measures. Multiple studies have addressed the issue of CT and MRI imaging in lumbar spinal stenosis. None showed superiority of one modality. METHODS: We performed a standardized qualitative and quantitative review of CT and MRI scans of 54 patients. Intra-observer and inter-observer reliability was determined between three reviewer using Kappa coefficient. Agreement between the two modalities was analyzed. ODI and SF-36 outcomes were correlated with the imaging assessments. RESULTS: Almost perfect intra-observer reliability for MRI was achieved by the two expert reviewers (κ = 0.91 for surgeon and κ = 0.92 for neuro-radiologist). For CT, substantial intra-observer agreement was found for the surgeon (κ = 0.77) while the neuro-radiologist was higher (κ = 0.96). For both CT and MRI the standardized qualitative assessment used by the two expert reviewers had a better inter-observer reliability than that between the expert reviewers and the general reporting radiologist, who did not utilize a standardized assessment system. When the qualitative assessment was compared directly, CT overestimated the degree of stenosis 20-35 % of the time (p < 0.05) while MRI overestimated the degree of stenosis 2-11 % of the time (p < 0.05). No correlation was found between qualitative and quantitative analysis with functional status. CONCLUSIONS: This study directly demonstrates that MRI is a more reliable tool than CT, but neither correlates with functional status. Both experience of the reader and the standardization of a qualitative assessment are influential to the reliability.

Cost-effectiveness Analysis of Existing Pedicle Screws Reusing Technique in Extension Revision Operation for Adjacent Segmental Stenosis After Lumbar Posterolateral Fusion.

STUDY DESIGN: Retrospective case-control study. OBJECTIVE: A cost-effectiveness analysis was performed by comparing patients who received extension revision operations for adjacent segment disease (ASD) reusing the pedicle screws extracted from fused segments with patients who received conventional surgery. SUMMARY OF BACKGROUND DATA: ASD often required extension revision surgery, and during extension surgery, pedicle screws may be reused by extracting from the fused segments of primary surgery. METHODS: Study examined 37 patients who received extension revision surgery for ASD from January 2003 to December 2013. For the fixation of extended segments during revision operation, in 16 cases the pedicle screws extracted from fused segments were reused (group R), and in 21 cases new pedicle screws were used (group C) as a conventional method. Clinical outcomes were evaluated by means of visual analog scale scores for lumbago and leg pain, and the Korean Oswestry Disability Index. Radiologic outcomes were evaluated from the extent of bone union. The total operating costs in the two groups were compared. RESULTS: Visual analog scale scores for lumbago and leg pain, and the Korean Oswestry Disability Index measured at final follow-up averaged 3.6 and 3.8, and 19.9 in group R, and 3.8 and 3.1, and 21.1 in group C, respectively (P = 0.280, P = 0.387, P = 0.751). For radiologic outcomes, there was one case of nonunion in each group. The cost of surgery was 5332 US dollars in group R, and 6109 US dollars in group C, respectively (P = 0.036). CONCLUSION: Reusing pedicle screws extracted from the fused segments during extension revision operation for ASD can reduce the cost of surgery, and achieves clinical and radiological results similar to those of the conventional operation. LEVEL OF EVIDENCE: 4.

Reliability of quantitative magnetic resonance imaging methods in the assessment of spinal canal stenosis and cord compression in cervical myelopathy.

STUDY DESIGN: Prospective, blinded reliability study of quantitative magnetic resonance imaging (MRI) measures in patients with cervical myelopathy. OBJECTIVE: To assess the intra- and interobserver reliability of commonly used quantitative MRI measures such as transverse area (TA) of spinal cord, compression ratio (CR), maximum canal compromise (MCC), and maximum spinal cord compression (MSCC). SUMMARY OF BACKGROUND DATA: There is no consensus on an optimal quantitative MRI method(s) in assessing canal stenosis and cord compression. METHODS: Seven surgeons performed measurements on 17 digital MR images, on 4 separate occasions. The degree of stenosis was evaluated by measuring TA and CR on axial T2, MCC, and MSCC on midsagittal T1- and T2-weighted MRI sequences, respectively. Statistical analyses included repeated-measures analysis of variance and intraclass correlation coefficients (ICCs). RESULTS: The mean ± SD for intraobserver ICC was 0.88 ± 0.1 for MCC, 0.76 ± 0.08 for MSCC, 0.92 ± 0.07 for TA, and 0.82 ± 0.13 for CR. In addition, the interobserver ICC was 0.75 ± 0.04 for MCC, 0.79 ± 0.09 for MSCC, 0.80 ± 0.05 for CR, and 0.86 ± 0.03 for TA. Higher degree of canal compromise (MCC) was associated with lower modified version of Japanese Orthopaedic Association Scale score (P = 0.05). Also, a strong association was found between MSCC and lower modified version of Japanese Orthopaedic Association Scale score, greater number of steps, and longer walking time (P < 0.05). CONCLUSION: All 4 measurement techniques demonstrated a good to moderately high degree of intra- and interobserver reliability. Highest reliability was noted in the assessment of T2-weighted sequences and axial MRI. Our results show that the measurements of MCC, MSCC, and CR are sufficiently reliable and correlate well with clinical severity of cervical myelopathy.

Facet-sparing lumbar decompression with a minimally invasive flexible MicroBlade Shaver® versus traditional decompression: quantitative radiographic assessment.

BACKGROUND: Laminectomy/laminotomy and foraminotomy are well established surgical techniques for treatment of symptomatic lumbar spinal stenosis. However, these procedures have significant limitations, including limited access to lateral and foraminal compression and postoperative instability. The purpose of this cadaver study was to compare bone, ligament, and soft tissue morphology following lumbar decompression using a minimally invasive MicroBlade Shaver® instrument versus hemilaminotomy with foraminotomy (HL). METHODS: The iO-Flex® system utilizes a flexible over-the-wire MicroBlade Shaver instrument designed for facet-sparing, minimally invasive "inside-out" decompression of the lumbar spine. Unilateral decompression was performed at 36 levels in nine human cadaver specimens, six with age-appropriate degenerative changes and three with radiographically confirmed multilevel stenosis. The iO-Flex system was utilized on alternating sides from L2/3 to L5/S1, and HL was performed on the opposite side at each level by the same investigator. Spinal canal, facet joint, lateral recess, and foraminal morphology were assessed using computed tomography. RESULTS: Similar increases in soft tissue canal area and decreases in ligamentum flavum area were noted in nondiseased specimens, although HL required removal of 83% more laminar area (P < 0.01) and 95% more bone resection, including the pars interarticularis and facet joints (P < 0.001), compared with the iO-Flex system. Similar increases in lateral recess diameter were noted in nondiseased specimens using each procedure. In stenotic specimens, the increase in lateral recess diameter was significantly (P = 0.02) greater following use of the iO-Flex system (43%) versus HL (7%). The iO-Flex system resulted in greater facet joint preservation in nondiseased and stenotic specimens. In stenotic specimens, the iO-Flex system resulted in a significantly greater increase in foraminal width compared with HL (24% versus 4%, P = 0.01), with facet joint preservation. CONCLUSION: The iO-Flex system resulted in significantly better decompression of the lateral recess and foraminal areas compared with HL, while preserving posterior spinal elements, including the facet joint.