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Purpose: This study aimed to develop machine learning methods to estimate bone mineral density and detect osteopenia/osteoporosis from conventional lumbar MRI (T1-weighted and T2-weighted images) and planar radiography in combination with clinical data and imaging parameters of the acquisition protocol., Methods: A database of 429 patients subjected to lumbar MRI, radiographs and dual-energy x-ray absorptiometry within 6 months was created from an institutional database. Several machine learning models were trained and tested (373 patients for training, 86 for testing) with the following objectives: (1) direct estimation of the vertebral bone mineral density; (2) classification of T-score lower than - 1 or (3) lower than - 2.5. The models took as inputs either the images or radiomics features derived from them, alone or in combination with metadata (age, sex, body size, vertebral level, parameters of the imaging protocol)., Results: The best-performing models achieved mean absolute errors of 0.15-0.16 g/cm 2 for the direct estimation of bone mineral density, and areas under the receiver operating characteristic curve of 0.82 (MRIs) - 0.80 (radiographs) for the classification of T-scores lower than - 1, and 0.80 (MRIs) - 0.65 (radiographs) for T-scores lower than - 2.5., Conclusions: The models showed good discriminative performances in detecting cases of low bone mineral density, and more limited capabilities for the direct estimation of its value. Being based on routine imaging and readily available data, such models are promising tools to retrospectively analyse existing datasets as well as for the opportunistic investigation of bone disorders., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Introduction: Low-grade isthmic and degenerative spondylolisthesis (DS) of the lumbar spine are distinct pathologies but both can be treated with lumbar decompression with fusion. In a very large cohort, we compared patient-reported outcome in relation to the pathology and chief complaint at baseline., Methods: This was a retrospective analysis using the EUROSPINE Spine Tango Registry. We included 582 patients (age 60 ± 15 years; 65% female), divided into four groups based on two variables: type of spondylolisthesis and chief pain complaint (leg pain (LP) versus back pain). Patients completed the COMI preoperatively and up to 5 years follow-up (FU), and rated global treatment outcome (GTO). Regression models were used to predict COMI-scores at FU. Pain scores and satisfaction ratings were analysed., Results: All patients experienced pronounced reductions in COMI scores. Relative to the other groups, the DS-LP group showed between 5% and 11% greater COMI score reduction (p < 0.01 up to 2 years' FU). This group also performed best with respect to pain outcomes and satisfaction. Long-term GTO was 93% at the 5 year FU, compared with between 82% and 86% in the other groups., Conclusion: Regardless of the type of spondylolisthesis, all groups experienced an improvement in COMI score after surgery. Patients with DS and LP as their chief complaint appear to benefit more than other patients. These results are the first to show that the type of the spondylolisthesis and its chief complaint have an impact on surgical outcome. They will be informative for the consent process prior to surgery and can be used to build predictive models for individual outcome., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Introduction: The Minimal Clinically Important Change (MCIC) is used in conjunction with Patient-Reported Outcome Measures (PROMs) to determine the clinical relevance of changes in health status. MCIC measures a change within the same person or group over time. This study aims to evaluate the variability in computing MCIC for the Core Outcome Measure Index (COMI) using different methods., Methods: Data from a spine centre in Switzerland were used to evaluate variations in MCIC for the COMI score. Distribution-based and anchor-based methods (predictive and nonpredictive) were applied. Bayesian bootstrap estimated confidence intervals., Results: From 27,003 cases, 9821 met the inclusion criteria. Distribution-based methods yielded MCIC values from 0.4 to 1.4. Anchor-based methods showed more variability, with MCIC values from 1.5 to 4.9. Predictive anchor-based methods also provided variable MCIC values for improvement (0.3-2.4), with high sensitivity and specificity., Discussion: MCIC calculation methods produce varying values, emphasizing careful method selection. Distribution-based methods likely measure minimal detectable change, while non-predictive anchor-based methods can yield high MCIC values due to group averaging. Predictive anchor-based methods offer more stable and clinically relevant MCIC values for improvement but are affected by prevalence and reliability corrections., Competing Interests: Declarations. Conflict of interest: The authors declare that they have no competing interests. Ethical Approval: Ethics approval and consent to participate. The study was performed in accordance with the Declaration of Helsinki and was approved by ethics (KEK-ZH-2023-01683). Patients gave their written informed consent before being included in the database. IRB: Ethics committee approval, KEK-ZH-2023-01683, (© 2024. The Author(s).)

Background: Psychosocial distress (the presence of yellow flags) has been linked to poor outcomes in spine surgery. The Core Yellow Flags Index (CYFI), a short instrument assessing the 4 main yellow flags, was developed for use in patients undergoing lumbar spine surgery. This study evaluated its ability to predict outcome in patients undergoing cervical spine surgery., Methods: Patients with degenerative spinal disorders (excluding myelopathy) operated in one centre, from 2015 to 2019, were asked to complete the CYFI at baseline and the Core Outcome Measures Index (COMI) at baseline and 3 and 12 months after surgery. The relationship between CYFI and COMI scores at baseline as well as the predictive ability of the CYFI on the COMI follow-up scores were tested using structural equation modelling., Results: From 731 eligible patients, 547 (61.0 ± 12.5 years; 57.2% female) completed forms at all three timepoints. On a cross-sectional basis, preoperative CYFI and COMI scores were highly correlated (β = 0.54, in men and 0.51 in women; each p < 0.001). CYFI added significantly and independently to the prediction of COMI at 3 months' FU in men (β = 0.36) and 12 months' FU in men and women (both β = 0.20) (all p < 0.001)., Conclusion: The CYFI had a low to moderate but significant and independent association with cervical spine surgery outcomes. Implementing the CYFI in the preoperative workup of these patients could help refine outcome predictions and better manage patient expectations., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Introduction: Selecting patients with lumbar degenerative spondylolisthesis (LDS) for surgery is difficult. Appropriate use criteria (AUC) have been developed to clarify the indications for LDS surgery but have not been evaluated in controlled studies., Methods: This prospective, controlled, multicentre study involved 908 patients (561 surgical and 347 non-surgical controls; 69.5 ± 9.7y; 69% female), treated as per normal clinical practice. Their appropriateness for surgery was afterwards determined using the AUC. They completed the Core Outcome Measures Index (COMI) at baseline and 12 months' follow-up. Multiple regression adjusting for confounders evaluated the influence of appropriateness designation and treatment received on the 12-month COMI and achievement of MCIC (≥ 2.2-point-reduction)., Results: As per convention, appropriate (A) and uncertain (U) groups were combined for comparison with the inappropriate (I) group. For the adjusted 12-month COMI, the benefit of surgery relative to non-surgical care was not significantly greater for the A/U than the I group (p = 0.189). There was, however, a greater treatment effect of surgery for those with higher baseline COMI (p = 0.035). The groups' adjusted probabilities of achieving MCIC were: 83% (A/U, receiving surgery), 71% (I, receiving surgery), 50% (A/U, receiving non-surgical care), and 32% (I, receiving non-surgical care)., Conclusions: A/U patients receiving surgery had the highest chances of achieving MCIC, but the AUC were not able to identify which patients had a greater treatment effect of surgery relative to non-surgical care. The identification of other characteristics that predict a greater treatment effect of surgery, in addition to baseline COMI, is required to improve decision-making., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: To describe the complications and the outcome of patients with achondroplasia undergoing thoracolumbar spinal surgery., Methods: Retrospective analysis of prospectively collected data of all patients with achondroplasia undergoing surgery within the years 1992-2021 at the thoracic and/or lumbar spine. The outcome was measured by analyzing the surgical complications and revisions. The patient-rated outcome was assessed with the COMI score from 2005 onwards., Results: A total of 15 patients were included in this study undergoing a total of 31 surgeries at 79 thoracolumbar levels. 12/31 surgeries had intraoperative complications consisting of 11 dural tears and one excessive intraoperative bleeding. 4/18 revision surgeries were conducted due to post-decompression hyperkyphosis. The COMI score decreased from 7.5 IQR 1.4 (range 7.1-9.8) preoperatively to 5.3 IQR 4.1 (2.5-7.5) after 2 years (p = 0.046)., Conclusion: Patients with achondroplasia, the most common skeletal dysplasia condition with short-limb dwarfism, are burdened with a congenitally narrow spinal canal and are commonly in need of spinal surgery. However, surgery in these patients is often associated with complications, namely dural tears and post-decompression kyphosis. Despite these complications, patients benefit from surgical treatment at a follow-up of 2 years after surgery., (© 2024. The Author(s).)

Purpose: The aim of this study was to investigate the risks and outcomes of patients with long-term oral anticoagulation (OAC) undergoing spine surgery., Methods: All patients on long-term OAC who underwent spine surgery between 01/2005 and 06/2015 were included. Data were prospectively collected within our in-house Spine Surgery registry and retrospectively supplemented with patient chart and administrative database information. A 1:1 propensity score-matched group of patients without OAC from the same time interval served as control. Primary outcomes were post-operative bleeding, wound complications and thromboembolic events up to 90 days post-surgery. Secondary outcomes included intraoperative blood loss, length of hospital stay, death and 3-month post-operative patient-rated outcomes., Results: In comparison with the control group, patients with OAC (n = 332) had a 3.4-fold (95%CI 1.3-9.0) higher risk for post-operative bleeding, whereas the risks for wound complications and thromboembolic events were comparable between groups. The higher bleeding risk was driven by a higher rate of extraspinal haematomas (3.3% vs. 0.6%; p = 0.001), while there was no difference in epidural haematomas and haematoma evacuations. Risk factors for adverse events among patients with OAC were mechanical heart valves, posterior neck surgery, blood loss > 1000 mL, age, female sex, BMI > 30 kg/m 2 and post-operative PTT levels. At 3-month follow-up, most patients reported favourable outcomes with no difference between groups., Conclusion: Although OAC patients have a higher risk for complications after spine surgery, the risk for major events is low and patients benefit similarly from surgery., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Study Design: Retrospective Cohort Study with prospectively collected data., Purpose: Transforaminal interbody fusion was initially designed for the lumbar spine. A similar approach was later introduced for the thoracic spine (TTIF). Here we report the surgical technique and the Core Outcome Measures Index (COMI) at 1-year and 2-year follow-ups, as well as the sagittal radiographic kyphosis correction of TTIF, achieved at 1 year and the latest follow-up., Methods: All TTIF procedures from 2012 to 2020 were included. COMI scores were collected preoperatively and at 1- and 2-year follow-ups. The sagittal angle between the upper and lower endplates at the segment where TTIF was performed was measured on preoperative, 1-year postoperative, and last available radiographs., Results: Seventy-nine TTIF procedures were performed for 64 patients (36% males; mean age 67.5 (SD 15.3) years). COMI score reduced from a mean value of 8.1 (SD 1.4) preoperatively to 4.7 (SD 2.7) at 1-year follow-up and 4.7 (SD 2.7) at 2-year follow-up. The mean correction of segmental kyphosis was 10.8 (SD 7.3, p < 0.0001) degrees at 1-year follow-up and 9.3 (SD 7.0, p < 0.0001) degrees at the final follow-up 3.4 (SD 1.4) years after the operation. Kaplan-Meier analysis for reoperations showed a 5-year survival of 91% (95% CI 0.795-1) for primary TTIF operations and survival of 77% (95% CI 0.651-0.899) for TTIFs performed after earlier fusion operations., Conclusions: TTIF is a feasible procedure in the thoracic spine. Kyphosis correction of approximately 10° was maintained at 1-year and final follow-up. Over 69% at 1-year and 61% at 2-year follow-up achieved MCID for COMI., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Patient-reported outcome measures (PROMs) are integral to the assessment of treatment success, but loss to follow-up (attrition) may lead to bias in the results reported. We sought to evaluate the extent, nature and implications of attrition in a long-established, single-centre spine registry., Methods: The registry contained the data of 15,264 consecutive spine surgery patients. PROMs included the Core Outcome Measures Index (COMI) and a rating of the Global Treatment Outcome (GTO) and Satisfaction with Care. Baseline characteristics associated with returning a 12-month PROM (= "responder") were analysed (logistic regression). The 3-month outcomes of 12-month responders versus 12-month non-responders were compared (ANOVA and Chi-square)., Results: In total, 14,758/15,264 (97%) patients (60 ± 17y; 46% men) had consented to the use of their registry data for research. Preoperative, 3-month post-operative and 12-month post-operative PROMs were returned by 91, 90 and 86%, respectively. Factors associated with being a 12-month responder included: greater age, born in the country of the study, no private/semi-private insurance, better baseline status (lower COMI score), fewer previous surgeries, less comorbidity and no perioperative medical complications. 12-month non-responders had shown significantly worse outcomes in their 3-month PROMs than had 12-month responders (respectively, 66% vs 80% good GTO ("treatment helped/helped a lot"); 77% vs 88% satisfied/very satisfied; and 49% vs 63% achieved MCIC on COMI)., Conclusion: Although attrition in this cohort was relatively low, 12-month non-responders displayed distinctive characteristics and their early outcomes were significantly worse than those of 12-month responders. If loss to follow-up is not addressed, treatment success will likely be overestimated, with erroneously optimistic results being reported., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Sagittal malalignment is a risk factor for mechanical complications after surgery for adult spinal deformity (ASD). Spinal loads, modulated by sagittal alignment, may explain this relationship. The aims of this study were to investigate the relationships between: (1) postoperative changes in loads at the proximal segment and realignment, and (2) absolute postoperative loads and postoperative alignment measures., Methods: A previously validated musculoskeletal model of the whole spine was applied to study a clinical sample of 205 patients with ASD. Based on clinical and radiographic data, pre-and postoperative patient-specific alignments were simulated to predict loads at the proximal segment adjacent to the spinal fusion., Results: Weak-to-moderate associations were found between pre-to-postop changes in lumbar lordosis, LL (r =  - 0.23, r =  - 0.43; p < 0.001), global tilt, GT (r = 0.26, r = 0.38; p < 0.001) and the Global Alignment and Proportion score, GAP (r = 0.26, r = 0.37; p < 0.001), and changes in compressive and shear forces at the proximal segment. GAP score parameters, thoracic kyphosis measurements and the slope of upper instrumented vertebra were associated with changes in shear. In patients with T10-pelvis fusion, moderate-to-strong associations were found between postoperative sagittal alignment measures and compressive and shear loads, with GT showing the strongest correlations (r = 0.75, r = 0.73, p < 0.001)., Conclusions: Spinal loads were estimated for patient-specific full spinal alignment profiles in a large cohort of patients with ASD pre-and postoperatively. Loads on the proximal segments were greater in association with sagittal malalignment and malorientation of proximal vertebra. Future work should explore whether they provide a causative mechanism explaining the associated risk of proximal junction complications., (© 2022. The Author(s).)

Introduction: The Oswestry Disability Index (ODI) and the Core Outcome Measures Index (COMI) are two commonly used self-rating outcome instruments in patients with lumbar spinal disorders. No formal crosswalk between them exists that would otherwise allow the scores of one to be interpreted in terms of the other. We aimed to create such a mapping function., Methods: We performed a secondary analysis of ODI and COMI data previously collected from 3324 patients (57 ± 17y; 60.3% female) at baseline and 1y after surgical or conservative treatment. Correlations between scores and Cohen's kappa for agreement (κ) regarding achievement of the minimal clinically important change (MCIC) score on each instrument (ODI, 12.8 points; COMI, 2.2 points) were calculated, and regression models were built. The latter were tested for accuracy in an independent set of registry data from 634 patients (60 ± 15y; 56.8% female)., Results: All pairs of measures were significantly positively correlated (baseline, 0.73; 1y follow-up (FU), 0.84; change-scores, 0.73). MCIC for COMI was achieved in 53.9% patients and for ODI, in 52.4%, with 78% agreement on an individual basis (κ = 0.56). Standard errors for the regression slopes and intercepts were low, indicating excellent prediction at the group level, but root mean square residuals (reflecting individual error) were relatively high. ODI was predicted as COMI × 7.13-4.20 (at baseline), COMI × 6.34 + 2.67 (at FU) and COMI × 5.18 + 1.92 (for change-score); COMI was predicted as ODI × 0.075 + 3.64 (baseline), ODI × 0.113 + 0.96 (FU), and ODI × 0.102 + 1.10 (change-score). ICCs were 0.63-0.87 for derived versus actual scores., Conclusion: Predictions at the group level were very good and met standards justifying the pooling of data. However, we caution against using individual values for treatment decisions, e.g. attempting to monitor patients over time, first with one instrument and then with the other, due to the lower statistical precision at the individual level. The ability to convert scores via the developed mapping function should open up more centres/registries for collaboration and facilitate the combining of data in meta-analyses., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: It is clear that individual outcomes of spine surgery can be quite heterogeneous. When consenting a patient for surgery, it is important to be able to offer an individualized prediction regarding the likely outcome. This study used a comprehensive set of data collected over 12 years in an in-house registry to develop a parsimonious model to predict the multidimensional outcome of patients undergoing surgery for degenerative pathologies of the thoracic, lumbar or cervical spine., Methods: Data from 8374 patients (mean age 63.9 (14.9-96.3) y, 53.4% female) were used to develop a model to predict the 12-month scores for the Core Outcome Measures Index (COMI) and its subdomain scores. The data were split 80:20 into a training and test set. The top predictors were selected by applying recursive feature elimination based on LASSO cross validation models. Based on the 111 top predictors (contained within 20 variables), Ridge cross validation models were trained, validated, and tested for each of 9 outcome domains, for patients with either "Back" (thoracic/lumbar spine) or "Neck" (cervical spine) problems (total 18 models)., Results: Among the strongest outcome predictors in most models were: preoperative scores for almost all COMI items (especially axial pain (back or neck) and peripheral pain (leg/buttock or arm/shoulder)), catastrophizing, fear avoidance beliefs, comorbidity, age, BMI, nationality, previous spine surgery, type and spinal level of intervention, number of affected levels, and surgeon seniority. The R 2 of the models on the validation/test sets averaged 0.16/0.13. A preliminary online tool was programmed to present the predicted outcomes for individual patients, based on their presenting characteristics. https://linkup.kws.ch/prognostictool ., Conclusion: The models provided estimates to enable a bespoke prediction of the outcome of surgery for individual patients with varying degenerative pathologies and baseline characteristics. The models form the basis of a simple, freely-available online prognostic tool developed to improve access to and usability of prognostic information in clinical practice. It is hoped that, following confirmation of its validity and practical utility, the tool will ultimately serve to facilitate decision-making and the management of patients' expectations., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Introduction: Various surgical techniques have been introduced for atlantoaxial (C1-C2) fusion, the most common being Magerl's (transarticular) or the Harms/Goel screw fixation. Common indications include degenerative osteoarthritis (OA), trauma or rheumatoid arthritis (RA). Only few, small studies have evaluated patient-reported outcomes after C1-C2 fusion. We investigated 2-year outcomes in a large series of consecutive patients undergoing isolated C1-C2 fusion., Methods: We analysed prospectively collected data (2005-2016) from our Spine outcomes database, collected within the framework of EUROSPINE's Spine Tango Registry. It included 126 patients (34 (27%) men, 92 (73%) women; mean (SD) age 67 ± 19 y) who had undergone first-time isolated C1-C2 fusion (61% Magerl, 39% Harms(-Goel)) at least 2 years ago for OA (83 (66%)), RA (20 (16%)), fracture (15 (12%)) or other (8 (6%)). Patients completed the multidimensional Core Outcome Measures Index (COMI; 0-10) and various single item outcomes., Results: Questionnaires were returned by 118/126 (94%) patients, 2 years post-operative. Mean COMI scores showed a significant reduction from baseline: 6.9 ± 2.4 to 2.7 ± 2.5 (p < 0.0001). Overall, 75% patients achieved the MCIC of ≥ 2.2 points reduction in COMI and 88% reported a good global outcome. 91% patients were satisfied/very satisfied with their care. Self-reported complications were declared by 16% patients and further surgery at the same segment, by 2.5%., Conclusion: In this large series with almost complete follow-up, C1-C2 fusion showed extremely good results. Despite the complexity of the intervention, outcomes surpassed those typically reported for simple procedures such as ACDF and lumbar discectomy, suggesting reservations about the procedure should perhaps be reviewed., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Introduction: Treatment failures in spine surgery are often attributable to poor patient selection and the application of inappropriate treatment. We used published appropriate use criteria (AUC) to evaluate the appropriateness of surgery in a large group of patients operated for lumbar degenerative spondylolisthesis (LDS) and to evaluate its association with outcome., Methods: This was a retrospective analysis of prospectively collected outcome data from patients operated in our Spine Centre, 2005-2012. Appropriateness of surgery was judged based on the AUC. Patients had completed the multidimensional Core Outcome Measures Index (COMI) before surgery and at 3 months' and 1, 2 and 5 years' follow-up (FU)., Results: In total, 448 patients (69.8 ± 9.6 years; 323 (72%) women) were eligible for inclusion and the AUC could be applied in 393 (88%) of these. Surgery was considered appropriate (A) in 234 (59%) of the patients, uncertain/equivocal (U) in 90 (23%) and inappropriate (I) in 69 (18%). A/U patients had significantly (p < 0.05) greater improvements in COMI than I patients at each FU time point. The minimal clinically important change (MCIC) score for COMI was reached by 82% A, 76% U and 54% I patients at 1-year FU (p < 0.001, I vs A and U); the odds of achieving MCIC were 3-4 times greater in A/U patients than in I patients., Conclusions: The results suggest a relationship between appropriateness of surgery for LDS and the improvements in COMI score after surgery. The findings require confirmation in prospective studies that also include a control group of non-operated patients.

Introduction: Being able to quantify the invasiveness of a surgical procedure is important to weigh up its associated risks, since invasiveness governs the blood loss, operative time and likelihood of complications. Mirza et al. (Spine (Phila Pa 1976) 33:2651-2661, 2008) published an invasiveness index for spinal surgery. We evaluated the validity of a modified version of the Mirza invasiveness index (mMII), adapted for use with registry data., Methods: A cross-sectional analysis was performed with data acquired from the Spine Tango registry including 21,634 patients. The mMII was calculated as the sum of six possible interventions on each vertebral level: decompression, fusion and stabilization either on anterior or posterior structures. The association between the mMII and blood loss, operative time and complications was evaluated using multiple regression, adjusting for possible confounders., Results: The mean (± SD) mMII was 3.9 ± 5.0 (range 0-40). A 1-point increase in the mMII was associated with an additional blood loss of 12.8% (95% CI 12.6-13.0; p < 0.001) and an increase of operative time of 10.4 min (95% CI 10.20-10.53; p < 0.001). The R 2 for the blood loss model was of 43% and for operative time, 47%. The mean mMII was significantly (p < 0.001) higher in patients with surgical complications (4.5 ± 5.6) and general medical complications (6.5 ± 7.0) compared to those without (3.8 ± 4.9). Our results were comparable to those reported in the original publication of Mirza et al. CONCLUSION: The mMII appeared to be a valid measure of surgical invasiveness in our study population. It can be used in predictor models and to adjust for surgical case-mix when comparing outcomes in different studies or different hospitals/surgeons in a registry.

Background: The American Society of Anaesthesiologists' Physical Status Score (ASA) is a key variable in predictor models of surgical outcome and "appropriate use criteria". However, at the time when such tools are being used in decision-making, the ASA rating is typically unknown. We evaluated whether the ASA class could be predicted statistically from Charlson Comorbidy Index (CCI) scores and simple demographic variables., Methods: Using established algorithms, the CCI was calculated from the ICD-10 comorbidity codes of 11'523 spine surgery patients (62.3 ± 14.6y) who also had anaesthetist-assigned ASA scores. These were randomly split into training (N = 8078) and test (N = 3445) samples. A logistic regression model was built based on the training sample and used to predict ASA scores for the test sample and for temporal (N = 341) and external validation (N = 171) samples., Results: In a simple model with just CCI predicting ASA, receiver operating characteristics (ROC) analysis revealed a cut-off of CCI ≥ 1 discriminated best between being ASA ≥ 3 versus < 3 (area under the curve (AUC), 0.70 ± 0.01, 95%CI,0.82-0.84). Multiple logistic regression analyses including age, sex, smoking, and BMI in addition to CCI gave better predictions of ASA (Nagelkerke's pseudo-R 2 for predicting ASA class 1 to 4, 46.6%; for predicting ASA ≥ 3 vs.  < 3, 37.5%). AUCs for discriminating ASA ≥ 3 versus < 3 from multiple logistic regression were 0.83 ± 0.01 (95%CI, 0.82-0.84) for the training sample and 0.82 ± 0.01 (95%CI, 0.81-0.84), 0.85 ± 0.02 (95%CI, 0.80-0.89), and 0.77 ± 0.04 (95%CI,0.69-0.84) for the test, temporal and external validation samples, respectively. Calibration was adequate in all validation samples., Conclusions: It was possible to predict ASA from CCI. In a simple model, CCI ≥ 1 best distinguished between ASA ≥ 3 and < 3. For a more precise prediction, regression algorithms were created based on CCI and simple demographic variables obtainable from patient interview. The availability of such algorithms may widen the utility of decision aids that rely on the ASA, where the latter is not readily available.

Purpose: We investigated whether outcomes after cervical total disc replacement (cTDR) are influenced by preoperative neck pain as the chief complaint., Methods: This was a retrospective study using data in our local spine surgery outcomes database, linked to EUROSPINE Spine Tango Registry. Patients completed questionnaires at baseline enquiring about the "chief complaint" [neck pain (NP), arm/shoulder pain (AP) or neurological deficits (ND)] and including the Core Outcome Measures Index (COMI); these were completed again at 24 months postoperatively, along with a rating of "global treatment outcome" (on a five-point scale, later dichotomized as "good" or "poor"). Differences in outcomes between the groups were examined using ANOVA. Multivariable regression analysis examined the effect of the chief pain location on 24-month outcomes, controlling for age, gender, comorbidity, baseline pain and COMI scores., Results: One hundred and fifty-nine consecutive patients were included, with a chief complaint of NP in 31%, AP in 38% and ND in 31%. The chief complaint groups did not differ in relation to their baseline COMI scores or their reductions in score from before surgery to 24 months after surgery (reduction: NP group, 4.4 ± 2.9 points; AP group, 4.7 ± 2.7; ND group, 4.3 ± 2.9; p = 0.78). Similarly, the percentage of patients reporting a "good global treatment outcome" at 24 months postoperatively did not differ between the groups (NP, 79%; AP, 77%; ND, 85%; p  = 0.64). The findings were consistent when controlling for possible confounders in multiple regression., Conclusions: Having neck pain as opposed to arm pain or neurological deficits as preoperative chief complaint had no significant impact on clinical outcome after cTDR. These slides can be retrieved under Electronic Supplementary Material.

Purpose: Spinal epidural lipomatosis (SEL) is defined as an abnormal and extensive accumulation of unencapsulated adipose tissue within the spinal epidural space. To date, there is a lack of high-level evidence studies reporting the outcome of surgical treatment of symptomatic SEL in patients with lumbar spinal stenosis (LSS). The aim was to compare clinical outcomes in patients with symptomatic LSS with and without SEL who underwent decompression surgery alone at the 12- and 24-month follow-up., Methods: One hundred and eighty-three patients met the inclusion criteria, of which 14 had mainly SEL on at least one level operated in addition to possible degenerative changes on other levels and 169 degenerative LSS only. The main outcomes were pain (Spinal Stenosis Measure (SSM) symptoms), disability (SSM function), and quality of life [EQ-5D-3L summary index (SI)] at 24-month follow-up, and minimal clinically important difference (MCID) in SSM symptoms, SSM function, and EQ-5D-3L SI., Results: The multiple regression linear models showed that SEL was associated with worse SSM symptoms (p = 0.045) and EQ-5D-3L SI scores (p = 0.026) at 24-month follow-up, but not with worse SSM function scores. Further, depression (in all models) was negatively associated with better clinical outcomes at 24-month follow-up. In the outcomes SSM symptoms and EQ-5D-3L SI, distinctly more patients in the classical LSS group reached MCID than in the SEL group (71.3% and 62.3% vs. 50.0% and 42.9%)., Conclusions: Our study demonstrated that decompression alone surgery was associated with significant improvement in disability in both groups at 2 years, but not in pain and quality of life in patients with SEL.

Background: Depression, anxiety, catastrophising, and fear-avoidance beliefs are key "yellow flags" (YFs) that predict a poor outcome in back patients. Most surgeons acknowledge the importance of YFs but have difficulty assessing them due to the complexity of the instruments used for their measurement and time constraints during consultations. We performed a secondary analysis of existing questionnaire data to develop a brief tool to enable the systematic evaluation of YFs and then tested it in clinical practice., Methods: The following questionnaire datasets were available from a total of 932 secondary/tertiary care patients (61 ± 16 years; 51% female): pain catastrophising (N = 347); ZUNG depression (N = 453); Hospital Anxiety and Depression Scale (anxiety subscale) (N = 308); fear-avoidance beliefs (N = 761). The single item that best represented the full-scale score was identified, to form the 4-item "Core Yellow Flags Index" (CYFI). 2422 patients (64 ± 16 years; 54% female) completed CYFI and a Core Outcome Measures Index (COMI) before lumbar spine surgery, and a COMI 3 and 12 months later (FU)., Results: The item-total correlation for each item with its full-length questionnaire was: 0.77 (catastrophising), 0.67 (depression), 0.69 (anxiety), 0.68 (fear-avoidance beliefs). Cronbach's α for the CYFI was 0.79. Structural equation modelling showed CYFI uniquely explained variance (p < 0.001) in COMI at both the 3- and 12-month FUs (β = 0.11 (women), 0.24 (men); and β = 0.13 (women), β = 0.14 (men), respectively)., Conclusion: The 4-item CYFI proved to be a simple, practicable tool for routinely assessing key psychological attributes in spine surgery patients and made a relevant contribution in predicting postoperative outcome. CYFI's items were similar to those in the "STarT Back screening tool" used in primary care to triage patients into treatment pathways, further substantiating its validity. Wider use of CYFI may help improve the accuracy of predictive models derived using spine registry data.

Introduction: Previous studies suggest that a meaningful and easily understood measure of treatment outcome may be the proportion of patients who are in a "patient acceptable symptom state" (PASS). We sought to quantify the score equivalent to PASS for different outcome instruments, in patients with adult spinal deformity (ASD)., Methods: We analysed the following 12-month questionnaire data from the European Spine Study Group (ESSG): Oswestry Disability Index (ODI; 0-100); Numeric Rating Scales (NRS; 0-10) for back/leg pain; Scoliosis Research Society (SRS) questionnaire; and an item "if you had to spend the rest of your life with the symptoms you have now, how would you feel about it?" (5-point scale, dichotomised with top 2 responses "somewhat satisfied/very satisfied" being considered PASS+, everything else PASS-). Receiver operating characteristics (ROC) analyses indicated the cut-off scores equivalent to PASS+., Results: Out of 1043 patients (599 operative, 444 non-operative; 51 ± 19 years; 84% women), 42% reported being PASS+ at 12 months' follow-up. The ROC areas under the curve were 0.71-0.84 (highest for SRS subscore), suggesting the questionnaire scores discriminated well between PASS+ and PASS-. The scores corresponding to PASS+ were > 3.5 for the SRS subscore (> 3.3-3.8 for SRS subdomains); ≤ 18 for ODI; and ≤ 3 for NRS pain. There were slight differences in cut-offs for subgroups of age, treatment type, aetiology, baseline symptoms, and sex., Conclusion: Most interventions for ASD improve patients' complaints but do not totally eliminate them. Reporting the percentage achieving a score equivalent to an "acceptable state" may represent a more stringent and discerning target for denoting treatment success in ASD. These slides can be retrieved under Electronic Supplementary Material.

Background: Unnecessarily long hospital stays are costly and inefficient. Studies have shown that the length of hospital stay (LOS) for spine surgical procedures is influenced by various disease-related or medical factors, but few have examined the role of socio-demographic/socio-economic (SDE) factors., Methods: This was a retrospective analysis of data from 10,770 patients (5056 men, 5714 women; 62 ± 15 years) with degenerative spinal disorders, collected prospectively in an in-house database within the framework of EUROSPINE's Spine Tango Registry. Surgeons completed the Tango surgery form (clinical history, demographics, surgical measures, complications), and patients, a baseline Core Outcome Measures Index. Stepwise linear regression analyses examined SDE predictors of LOS, controlling for potential medical/biological factors., Results: The mean LOS was 7.9 ± 5.2 days. The final model accounted for 42% of variance in LOS, with SDE variables explaining 13% variance and medical/surgical predictors, 29%. In the final model, the SDE factors age and being female were significant independent predictors of LOS, whereas others were either non-significant (insurance status, being of Swiss nationality, being a smoker) or reached only borderline significance (p < 0.1) (BMI). Controlling for all other SDE and medical/surgical confounders, being female was associated with 1.11-day longer LOS (95% CI 0.96-1.27; p < 0.0001)., Conclusions: Patients of advanced age and female gender are at increased risk of longer hospital stay after surgery for degenerative spinal disorders. Further studies should seek to understand the reasoning behind the gender disparity, in order to minimise potentially unnecessary costs of prolonged LOS. Targeted preoperative discharge planning may improve the utilisation of hospital resources. These slides can be retrieved under Electronic Supplementary Material.

Purpose: Surgical treatment of early-onset scoliosis (EOS) requires a balance between maintained curve correction and the capacity for spinal and thoracic growth. Spinal fusion creates irreversible conditions that prevent the implementation of further treatment methods. Our hypothesis was that non-fused anchors in growth guidance show a comparable outcome as the technique described in the literature, which involves spondylodesis of the anchoring segments., Methods: This retrospective study analysed 148 surgeries in 22 EOS patients (11 female, 11 male) over a 15-year period. Patients underwent surgery with non-fused anchors and growth guidance techniques. Scoliosis, kyphosis, growth and anchoring segments were measured. For the latter, a new measuring technique was developed. Complications were recorded and classified., Results: The mean Cobb angle reduced from 73.5 ± 24.4° to 28.4 ± 16.2° (60.2 ± 22.9%, p < 0.001) at the last follow-up. Spinal growth T1-S1 and T1-T12 were 41.1 ± 23.3 mm and 24.9 ± 16.6 mm (p < 0.001), respectively. Growth at the cranial and caudal anchoring segment was 1.5 mm/segment/year and 1.9 mm/segment/year, respectively. A total of 63 complications were documented in 20 patients, with 40 requiring unplanned revision surgery. Definitive spondylodesis was performed in three patients., Conclusion: Patients demonstrated a significant spinal growth including the anchoring segments. A comparable correction in Cobb angle and the type of complications was noted, although the rate of device-related complications was higher. No permanent impairment was reported. The rate of device-related complications is acceptable and outweighed by the significant degree of growth preservation and more flexible and individualised treatment strategy for patients with EOS. These slides can be retrieved under Electronic Supplementary Material.

Purpose: The aim of this study was to investigate the difference in patient-reported outcomes and surgical complication rates between lumbar procedures carried out either by experienced board-certified spine surgeons (BCS) or by supervised spine surgery residents (RES) in a large Swiss teaching hospital., Methods: This was a single-center retrospective analysis of data collected prospectively within the framework of the EUROSPINE Spine Tango Registry. It involved the data of 1415 patients undergoing first-time surgery in our institution between the years 2004 and 2016. Patients were divided into three groups based on the surgical procedure: lumbar single-level fusion (SLF), single-level decompression (SLD) for lumbar spinal stenosis and disc hernia procedures (DH). Patient-reported outcome measures (primary outcome) included the multidimensional Core Outcome Measures Index (COMI) preoperatively and 3 and 12 months postoperatively plus single items concerning satisfaction with care and global treatment outcome (GTO). Secondary outcomes included surgical variables such as blood loss, duration of surgery, complication rates and length of stay., Results: There were no significant differences between the RES and BCS patient groups for most of the demographic and baseline clinical variables with the exception of age in the SLD group (p = 0.012), BMI in the DH group (p = 0.02) and leg pain in the SLF group (p = 0.03). COMI scores improved significantly after all three types of procedure (p < 0.0001) without significant difference (p > 0.05) between the patients of RES and BCS. There was no significant difference (p > 0.05) between RES and BCS patients with regard to satisfaction and GTO. There were no significant differences between RES and BCS (p > 0.05) in the surgical or medical complication rates., Conclusion: In the given setting, surgical training of spine surgery residents under guided supervision by board-certified spine surgeons was shown to be safe, as it was not associated with greater morbidity or mortality. Furthermore, it had no detrimental influence on patient-reported outcomes. The findings can be used to give reassurance to prospective patients that are to be operated on by supervised spine surgery residents. These slides can be retrieved under Electronic Supplementary Material.

Purpose: We compared the value of different uni- and multimodal intraoperative neurophysiological monitoring (IONM) methods on the detection of neurological complications during spine surgery., Methods: IONM data derived from sensory spinal and cortical evoked potentials combined with continuous electromyography monitoring, motor evoked potentials and spinal recording were evaluated in relation to subsequent post-operative neurological changes. Patients were categorised based on their true-positive or true-negative post-operative neurological status., Results: In 2728 consecutive patients we had 909 (33.3%) IONM alerts. We had 8 false negatives (0.3%) with post-operative radicular deficit that completely recovered within 3 months, except for one. There was no false negative for spinal cord injury. 107 were true positives, and 23 were false positives. Multimodal IONM sensitivity and specificity were 93.0% and 99.1%, respectively. The frequency of neurological complications including minor deficits was 4.2% (n = 115), of which 0.37% (n = 10) were permanent. Analysis of the single IONM modalities varied between 13 and 81% to detect neurological complications compared with 93% when using all modalities., Conclusion: Multimodal IONM is more effective and accurate in assessing spinal cord and nerve root function during spine surgeries to reduce both neurological complications and false-negative findings compared to unimodal monitoring. We recommend multimodal IONM in all complex spine surgeries. These slides can be retrieved from Electronic Supplementary Material.

Purpose: Proximal junctional kyphosis and failure are frequent complications in adult spinal deformity surgery with long fusion constructs. The aim of this study was to assess the biomechanics of the proximal segment for fusions of various lengths., Methods: A previously established musculoskeletal model of thoracolumbar spine was used to simulate full-range flexion task for fusions (modeled by introduction of rigid constraints) with lower instrumented vertebrae at L5 or S1 and upper instrumented vertebrae (UIV) at any level above, up to T2. Inverse dynamics simulations with force-dependent kinematics were performed for gradually increasing spinal flexion in order to predict global and segmental range of flexion, maximum passive moment, segmental compression and shear forces, which were compared to the uninstrumented case., Results: For long fusions, with the UIV at T11 or higher, the model predicted an increase in segmental flexion (by 33-860%, or 1.6°-4.7°) and passive moment (by 39-1370%, or 13-31 Nm) at the proximal junction-generally increasing with fusion length. While the maximum shear force was 57-239% (135-283 N) higher for the proximal junction at the upper thorax (UIV at T6 or above), the compression forces were reduced by up to 44% (375 N)., Conclusions: The length of the instrumentation has an important effect on the proximal segment biomechanics. Despite the limitations of the current model, musculoskeletal modeling appears to be a promising and versatile method to support planning of spinal instrumentation surgeries in the future. These slides can be retrieved under Electronic Supplementary Material.

Purpose: Studies comparing the outcome of spine surgery with that of large-joint replacement report equivocal findings. The patient-reported outcome measures (PROMs) used in such studies are typically generic and may not be sufficiently sensitive to the successes/failures of treatment. This study compared different indices of "success" in patients undergoing surgery for degenerative disorders of the lumbar spine, hip, or knee, using a validated, multidimensional, and joint-specific PROM., Methods: Preoperatively and 12 months postoperatively, 4594 patients (3937 lumbar spine, 368 hip, 269 knee) undergoing first-time surgery completed a PROM that included the Core Outcome Measures Index (COMI) for the affected joint. The latter comprises a set of single items on pain, function, symptom-specific well-being, quality of life, and disability-all in relation to the specified joint problem. Other single-item ratings of treatment success were made 12 months postoperatively., Results: In multiple regression analyses, controlling for confounders, the mean improvement in COMI at 12 months was greatest for the hip patients and lowest for those with degenerative spinal deformity (= the statistical reference group) (p < 0.05). Compared with spinal deformity, the odds of achieving "success" were: higher for hip (OR 4.6; 95% CI 2.5-8.5) and knee (OR 4.0; 95% CI 2.1-7.7) (no difference between spine subgroups) for "satisfaction with care"; higher for hip (OR 16.9; 95% CI 7.3-39.6), knee (OR 6.3; 95% CI 3.4-11.6), degenerative spondylolisthesis (OR 1.6; 95% CI 1.2-2.2), and herniated disc (OR 1.7; 95% CI 1.2-2.4) for "global treatment outcome"; and higher for hip (OR 13.8; 95% CI 8.8-21.6), knee (OR 5.3; 95% CI 3.6-7.8), degenerative spondylolisthesis (OR 1.6; 95% CI 1.3-2.1), and herniated disc (1.5; 95% CI 1.1-2.0) for "patient-acceptable symptom state". Patient-rated complications were the greatest in degenerative spinal deformity (29%) and the lowest in hip (18%)., Conclusions: The current study is the largest of its kind and the first to use a common, but joint-specific instrument to report patient-reported outcomes after surgery for degenerative disorders of the spine, hip, or knee. The findings provide a sobering account of the significantly poorer outcomes after spine surgery compared with large-joint replacement. Further work is required to hone the indications and patient selection criteria for spine surgery. The data should be used to lobby research funding-bodies, governmental agencies, industry, and charitable foundations to invest more in spine research/registries, in the hope of ultimately improving spine outcomes. These slides can be retrieved under Electronic Supplementary Material.

Purpose: Patient-rated measures are considered the gold standard for assessing the outcome of spine surgery, but there is no consensus on the appropriate timing of follow-up. Journals often demand a minimum 2-year follow-up, but the indiscriminate application of this principle may not be warranted. We examined the course of change in patient outcomes up to 5 years after surgery for degenerative spinal disorders., Methods: The data were evaluated from 4287 consecutive patients (2287 women, 2000 men; aged 62 ± 15 years) with degenerative disorders of the thoracolumbar spine, undergoing first-time surgery at the given level between 01/01/2005 and 31/12/2011. The Core Outcome Measures Index (COMI; scored 0-10) was completed by 4012 (94%) patients preoperatively, 4008 (93%) at 3-month follow-up, 3897 (91%) at 1-year follow-up, 3736 (87%) at 2-year follow-up, and 3387 (79%) at 5-year follow-up. 2959 (69%) completed the COMI at all five time-points., Results: The individual COMI change scores from preoperatively to the various follow-up time-points showed significant correlations ranging from r = 0.50 (for change scores at the earliest vs the latest follow-up) to r = 0.75 (for change scores after 12- vs 24-month follow-up). Concordance with respect to whether the minimum clinically important change score was achieved at consecutive time-points was also good (70-82%). COMI decreased significantly (p < 0.05) from preop to 3 months (by 3.6 ± 2.8 points) and from 3 to 12 months (by 0.3 ± 2.4 points), then levelled off up to 5 years (0.04-0.05 point change; p > 0.05). The course of change up to 12 months differed slightly (p < 0.05) depending on pathology/whether fusion was carried out. For patients undergoing simple decompression, 3-month follow-up was sufficient; those undergoing fusion continued to show further slight but significant change up to 12 months., Conclusions: Stable group mean COMI scores were observed for all patients from 12 months postoperatively onwards. The early postoperative results appeared to herald the longer term outcome. As such, a 'wait and see policy' in patients with a poor initial outcome at 3 months is not advocated. The insistence on a 2-year follow-up could result in a failure to intervene early to achieve better long-term outcomes.

Purpose: Lumbar central spinal stenosis (LSS) is one of the most common reasons for spine surgery in the elderly patient. Magnetic resonance imaging (MRI) represents the gold standard for the assessment of LSS and can be used to obtain quantitative measures of the dural sac cross-sectional area (DCSA) or qualitative measures (morphological grades A-D) of the rootlet/cerebrospinal fluid ratio. This study investigated the intercorrelation between these two MRI evaluation methods and explored their respective relationships with the patient baseline clinical status and outcome 12 months after surgery., Methods: This was a retrospective analysis of prospectively collected data from 157 patients (88 male, 69 female; age 72 ± 7 years) who were undergoing first-time surgery for LSS. Patients with foraminal or isolated lateral stenosis were excluded. The Core Outcome Measures Index (COMI) was completed before and 12 months after surgery. Preoperative T2 axial MRIs were blinded and independently evaluated for DCSA and morphological grade. Spearman rank correlation coefficients described the relationship between the two MRI measures of stenosis severity and between each of these and the COMI baseline and change-scores (pre to 12 months' postop). Multiple logistic regression analysis (controlling for baseline COMI, age, gender, number of operated levels, health insurance status) was used to analyse the influence of stenosis severity on the achievement of the minimum clinically important change (MCIC) score for COMI and on global treatment outcome (GTO)., Results: There was a correlation of ρ = -0.69 (p < 0.001) between DCSA and morphological grade. There was no significant correlation between COMI baseline scores and either DCSA or morphological grades (p > 0.85). However, logistic regression revealed significant (p < 0.05) associations between stenosis ratings and 12-month outcome, whereby patients with more severe stenosis (as measured using either of the methods) benefited more from the surgery. Patients with a DCSA <75 mm 2 or morphological grade D had a 4-13-fold greater odds of achieving the MCIC for COMI or a "good" GTO, compared with patients in the least severe categories of stenosis., Conclusions: Postoperative outcome was clearly related to the degree of preoperative radiological LSS. The two MRI methods appeared to deliver similar information, as given by the relatively strong correlation between them and their comparable performance in relation to baseline and 12-month outcomes. However, the qualitative morphological grading can be performed in an instant, without measurement tools, and does not deliver less clinically useful information than the more complex and time-consuming measures; as such, it may represent the preferred method in the clinical routine for assessing the extent of radiological stenosis and the likelihood of a positive outcome after decompression.

Purpose: To evaluate the incidence and course of iatrogenic L5 radiculopathy after reduction and instrumented fusion of high-grade L5-S1 isthmic spondylolisthesis and the role of intraoperative neurophysiological monitoring (IONM)., Methods: Consecutive patients treated for high-grade spondylolisthesis with IONM from 2005 to 2013 were screened for eligibility. Prospectively collected clinical and surgical data as well as radiographic outcomes were analyzed retrospectively. Patients completed the multidimensional Core Outcome Measures Index (COMI) before and at 3, 12, and 24 months after surgery., Results: Seventeen patients were included, with a mean age of 26.3 (±9.5) years. Mean preoperative L5-S1 slip was 72% (±21%) and was reduced to 19% (±13%) postoperatively. Mean loss of reduction at last follow-up [mean 19 months (±14, range 3-48 months)] was 3% (±4.3%). Rate of new L5 radiculopathy with motor deficit (L5MD) after surgery was 29% (five patients). Four patients fully recovered after 3 months, one patient was lost to neurologic follow-up. IONM sensitivity and specificity for postoperative L5MD was 20 and 100%, respectively. COMI, back pain and leg pain scores showed significant (p < 0.001) improvements at 3 months postoperatively, which were retained up to 24 months postoperatively., Conclusions: Transient L5 radiculopathy after reduction and instrumented fusion of high-grade spondylolisthesis is frequent. With IONM the risk of irreversible L5 radiculopathy is minimal. If IONM signal changes recover, full clinical recovery is expected within 3 months. Overall, patient-reported outcome of reduction and instrumented fusion of high-grade spondylolisthesis showed clinically important improvement.

Purpose: Patients enrolled in clinical studies typically represent a sub-set of all who are eligible, and selection bias may compromise the generalizability of the findings. Using Registry data, we evaluated whether surgical patients recruited by one of the referring centres into the Lumbar Spinal Stenosis Outcome Study (LSOS; a large-scale, multicentre prospective observational study to determine the probability of clinical benefit after surgery) differed in any significant way from those who were eligible but not enrolled., Methods: Data were extracted for all patients with lumbar spinal stenosis registered in our in-house database (interfaced to Eurospine's Spine Tango Registry) from 2011 to 2013. Patient records and imaging were evaluated in relation to the admission criteria for LSOS to identify those who would have been eligible for participation but were not enrolled (non-LSOS). The Tango surgery data and Core Outcome Measures Index (COMI) data at baseline and 3 and 12 months after surgery were analysed to evaluate the factors associated with LSOS enrolment or not., Results: 514 potentially eligible patients were identified, of which 94 (18%) were enrolled into LSOS (range 2-48% for the 6 spine surgeons involved in recruiting patients) and 420 (82%) were not; the vast majority of the latter were due to non-referral to the study by the surgeon, with only 5% actually refusing participation. There was no significant difference in gender, age, BMI, smoking status, or ASA score between the two groups (p ≥ 0.18). Baseline COMI was significantly (p = 0.002) worse in the non-LSOS group (7.4 ± 1.9) than the LSOS group (6.7 ± 1.9). There were no significant group differences in any Tango surgery parameters (additional spine patholothegies, operation time, blood loss, complications, etc.) although significantly more patients in the non-LSOS group had a fusion procedure (38 vs 18% in LSOS; p = 0.0004). Postoperatively, neither the COMI nor its subdomain scores differed significantly between the groups (p > 0.05). Multiple logistic regression revealed that worse baseline COMI (p = 0.021), surgeon (p = 0.003), and having fusion (p = 0.014) predicted non-enrolment in LSOS., Conclusion: A high proportion of eligible patients were not enrolled in the study. Non-enrolment was explained in part by the specific surgeon, worse baseline COMI status, and having a fusion. The findings may reflect a tendency of the referring surgeon not to overburden more disabled patients and those undergoing more extensive surgery with the commitments of a study. Beyond these factors, non-enrolment appeared to be somewhat arbitrary, and was likely related to surgeon forgetfulness, time constraints, and administrative errors. Researchers should be aware of potential selection bias in their clinical studies, measure it (where possible) and discuss its implications for the interpretation of the study's findings.

Purpose: Few studies have used multivariate models to quantify the effect of multiple previous spine surgeries on patient-oriented outcome after spine surgery. This study sought to quantify the effect of prior spine surgery on 12-month postoperative outcomes in patients undergoing surgery for different degenerative disorders of the lumbar spine., Methods: The study included 4940 patients with lumbar degenerative disease documented in the Spine Tango Registry of EUROSPINE, the Spine Society of Europe, from 2004 to 2015. Preoperatively and 12 months postoperatively, patients completed the multidimensional Core Outcome Measures Index (COMI; 0-10 scale). Patients' medical history and surgical details were recorded using the Spine Tango Surgery 2006 and 2011 forms. Multiple linear regression models were used to investigate the relationship between the number of previous surgeries and the 12-month postoperative COMI score, controlling for the baseline COMI score and other potential confounders., Results: In the adjusted model including all cases, the 12-month COMI score showed a 0.37-point worse value [95 % confidence intervals (95 % CI) 0.29-0.45; p < 0.001] for each additional prior spine surgery. In the subgroup of patients with lumbar disc herniation, the corresponding effect was 0.52 points (95 % CI 0.27-0.77; p < 0.001) and in lumbar degenerative spondylolisthesis, 0.40 points (95 % CI 0.17-0.64; p = 0.001)., Conclusions: We were able to demonstrate a clear "dose-response" effect for previous surgery: the greater the number of prior spine surgeries, the systematically worse the outcome at 12 months' follow-up. The results of this study can be used when considering or consenting a patient for further surgery, to better inform the patient of the likely outcome and to set realistic expectations.

Purpose: Few studies have examined the effectiveness of surgical treatment for adult degenerative scoliosis (ADS) using validated patient-orientated outcome instruments. This study reports patient outcomes in a large, consecutive series of patients being treated for ADS by simple decompression (D), short fusion (SF), or long fusion (LF)., Methods: Our local spine surgery database (part of the Eurospine Spine Tango Registry) was used to acquire the data from patients with ADS undergoing D, SF or LF. Preoperatively and at 12 and 24 months follow-up (FU), patients completed the multidimensional Core Outcome Measures Index (COMI; 0-10); at FU, satisfaction and global outcome were rated on a five-point Likert scale and dichotomised as "good" and "poor", and patient-rated complications were recorded., Results: 173 patients took part (81 D, 53 SF, 39 LF). Compared with the two fusion groups, the D group was significantly older, had more comorbidity, and had more leg pain than back pain (each p < 0.05). There were significant differences among the groups for operation duration, blood loss and general complications (each p < 0.05), in each case with the LF group showing the greatest values and the D group the lowest values. However, patient-rated complications were not significantly different between the groups (p > 0.89). Further surgery within the 2-year follow-up was required in 7 % of the D group, 15 % in SF and 28 % in LF. All groups benefited significantly from surgery with no significant differences (p > 0.05) between them: improvement in COMI after 24 months was 2.9 ± 2.8 points for D, 3.1 ± 3.3 points for SF and 3.2 ± 3.1 points for LF; a "good global outcome" was recorded for 69, 74 and 76 % patients, respectively., Conclusions: Despite the complexity of the disease, patient-orientated outcomes after surgery for ADS were similar to those previously reported using the same outcome instruments in patients with lumbar stenosis and degenerative spondylolisthesis. The use of D, SF and LF for ADS yielded similarly good results from the patient's perspective. This most likely reflects careful and appropriate patient selection. Further analyses are warranted to identify baseline variables predicting the 26-31 % cases in each group with a poor outcome.

Congenital malformations of the spine are caused by genetic and teratogenic factors. By means of asymmetrical longitudinal growth of the spine they can lead to deformity, most commonly to scoliosis. The malformations can be classified as failure of formation, failure of segmentation and mixed-type malformations. The extent of the deformity and its progression are determined by the remaining growth potential and the location and type of malformation. Up to one third of such deformities are associated with some sort of cardiac or urogenital malformation. The treatment concept is typically determined on an individual basis. Mild deformities often remain undetected. Conservative treatment using a brace has no substantial effect on the primary curve but might be helpful in the treatment of long sweeping, flexible, secondary curves. If rapid progression is documented or expected, surgical intervention as early as possible is warranted to prevent secondary structural changes. The surgical treatment should be focused on and limited to the site of malformation. The aim of surgery is the correction of the deformity at the site of asymmetrical growth. This can be achieved either by resection of a hemivertebra or by performing a vertebral column resection or other type of osteotomy. If notable compensatory, secondary curves are present, these can be corrected with growing rod constructs. The aim of all types of treatment is the correction of existing deformity or the prevention of its progression, in order to ensure balanced growth of the healthy regions of the spine. The present paper discusses the conservative and surgical treatment modalities available to achieve these aims.

Purpose: The Core Outcome Measure Index (COMI) is a short, multidimensional outcome instrument developed for the evaluation of patients with spinal conditions. The aim of this study was to produce a cross-culturally adapted and validated Hungarian version of the COMI Back questionnaire., Methods: A cross-cultural adaptation of the COMI into Hungarian was carried out using established guidelines. Low back pain patients completed a booklet of questionnaires containing the Hungarian versions of COMI, Oswestry Disability Index (ODI) and WHO Quality of Life-BREF assessment (WHOQOL-BREF). The validation of the COMI included assessment of its construct validity, reliability, and responsiveness., Results: 145 patients participated in the assessment of reliability and 159 surgically treated patients were included in the responsiveness study. Excellent correlation was found between COMI and ODI scores (rho = 0.83, p < 0.01). The COMI showed a very good correlation with the physical subscale of WHOQOL-BREF (rho = -0.75, p < 0.01) and pain (rho = 0.68, p < 0.01). Test-retest analysis showed that Hungarian COMI is a reliable measurement tool (ICC = 0.92) with an acceptable standard error of measurement (SEM = 0.59) and minimum detectable change (MDC = 1.63). Internal responsiveness analysis indicated a large effect size (1.16) for the change in COMI score after lumbar surgery. The area under the ROC curve (AUC) for the COMI score compared with the global outcome of the surgery was 0.87., Conclusion: The translation and cross-cultural adaptation of the COMI into the Hungarian language was successful, resulting in a reliable and valid measurement tool with good clinimetric properties.

Purpose: Recent studies suggest that the location of predominant pain (back or leg) can be a significant predictor of the outcome of surgery for degenerative spinal disorders. However, others challenge the notion that the predominant symptom can be reliably identified. This study examined the validity of a single item used to determine the most troublesome symptom., Methods: A total of 2,778 patients with degenerative disorders of the lumbar spine scheduled for surgery with the goal of pain relief completed a questionnaire enquiring as to their most troublesome symptom ["main symptom"; back pain (BACK) or leg/buttock pain (LEG)]. They also completed separate 0-10 graphic rating scales for back pain (LBP) and leg/buttock pain (LP) intensity. Receiver operating characteristics (ROC) analysis was used to determine the accuracy with which the "LP minus LBP" score was able to classify patients into their declared "main symptom" group. Sub-studies evaluated the test-retest reliability of the patients' self-rated pain scores (N = 45) and the agreement between the main symptom declared by the patient in the questionnaire and that documented by the surgeon after the clinical consultation (N = 118)., Results: Test-retest reliability of the back and leg pain scores was good (ICC₂,₁ of 0.8 for each), as was patient-surgeon agreement regarding the main symptom (BACK or LEG) (κ value 0.79). In the BACK group, the mean values for pain intensity were 7.3 ± 2.0 (LBP) and 5.2 ± 2.9 (LP); in the LEG group, they were 4.3 ± 2.9 (LBP) and 7.5 ± 1.9 (LP). The area under the curve for the ROC was 0.95 (95 % CI 0.94-0.95), indicating excellent discrimination between the BACK and LEG groups based on the "LP minus LBP" scores. A cutoff score >0.0 for "LP minus LBP" score gave optimal sensitivity and specificity for indicating membership of the LEG group (sensitivity 79.1%, specificity 95.7%)., Conclusions: The responses on the single item for the "main symptom" were in good agreement with the differential ratings on the 0-10 pain scales for LBP and LP intensity. The cutoff >0 for "LP minus LBP" for classifying patients as LEG pain predominant seemed appropriate and suggests good concurrent validity for the single-item measure. The single item may be of use in sub-grouping patients with the same disorder (e.g. spondylolisthesis) or as an indication in surgical decision-making.

Purpose: The ageing of the population will see a growing number of patients presenting for spine surgery with appropriate indications but numerous medical comorbidities. This complicates decision-making, requiring that the likely benefit of surgery (outcome) be carefully weighed up against the potential risk (complications). We assessed the influence of comorbidity on the risks and benefits of spine surgery., Methods: 3,549/4,053 patients with degenerative lumbar disorders, undergoing surgery with the goal of pain relief, completed the multidimensional Core Outcome Measures Index (COMI; scored 0-10) before and 12 months after surgery. At 12 months postoperatively, they also rated the global treatment outcome and their satisfaction with care. Using the Eurospine Spine Tango Registry, surgeons documented surgical details, American Society of Anesthesiologists comorbidity (ASA) grades and perioperative surgical and general complications., Results: 29.0% patients were rated as ASA1 (normal healthy), 45.7% as ASA2 (mild/moderate systemic disease), 24.9% as ASA3 (severe), and just 0.4% as ASA4 (life-threatening). In going from ASA1 to ASA3 (ASA4 group too small), surgical complications increased significantly from 5.0 to 14.5% and general complications increased from 2.9 to 15.7%; 12-month outcomes showed a corresponding decline, with a good global outcome being reported by 79% ASA1 patients, 76% ASA2, and 68% ASA3. Satisfaction with treatment was 87, 85, and 79%, respectively, and reduction in COMI was 4.2 ± 2.9, 3.7 ± 3.0, and 3.4 ± 3.0 points, respectively. Multiple regression analysis revealed a significant (p < 0.0001) independent effect of ASA grade on both complications and outcome., Conclusion: The negative impact of comorbidity on the outcome of spine surgery has not been well investigated/quantified to date. The ASA grade may be helpful in producing algorithms for decision-making and preoperative counselling regarding the corresponding risks and benefits of surgery.

Purpose: Early onset spinal deformities (EOSD) can be life-threatening in very young children. In the growing spine, surgical intervention is often unavoidable and should be carried out as soon as possible. A deformed section of the spine not only affects the development of the remaining healthy spine, but also that of the chest wall (which influences pulmonary function), the extremities and body balance. Posterior vertebral column resection (PVCR) represents an effective surgical solution to address such problems. However, reports in the literature concerning PVCR are mostly limited to its use in adolescents or adults. The purpose of this study was to illustrate our experience with PVCR in EOSD and to describe the surgical technique with respect to the unique anatomy of young children., Materials and Methods: Four children [mean age 3.7 (range 2.5-5.2) years] with severe spinal deformity underwent PVCR through a single approach. Multimodal intraoperative monitoring was used in all cases. Surgery included one stage posterior circumferential resection of one vertebral body along with the adjoining intervertebral discs and removal of all posterior elements. A transpedicular screw-rod system was used for correction and stabilisation. Fusion was strictly limited to the resection site, allowing for later conversion into a growing rod construct at the remaining spine, if necessary. Relevant data were extracted retrospectively from patient charts and long spine radiographs., Results: The mean operation time was 500 (range 463-541) min, with an estimated blood loss of 762 (range 600-1,050) ml. Mean follow-up time was 6.3 (range 3.5-12.4) years. After PVCR, the mean Cobb angle for scoliosis was reduced from 69° (range 50-99°) to 29° (5-44°) and the sagittal curvature (kyphosis) from 126° (87-151°) to 61° (47-75°). The mean correction of scoliosis was 57 % (18-92°) and of kyphosis, 51 % (44-62°). There were no spinal cord-related complications. In three patients, spinal instrumentation for growth guidance (fusion less growing rod technique) was applied. Two patients had complications: one patient had a complication of anesthesia, halo pin failure, and revision surgery with extension of the instrumentation cranially due to loss of correction; the second patient had a postoperative infection, which required plastic reconstructive measures., Conclusion: PVCR appears to be an effective technique to treat severe EOSD. There are important differences in its use in young children when compared with older patients. In patients with EOSD, additional surgical procedures are often necessary during growth, and hence non-fusion instrumentation beyond the vertebral resection site is advantageous, as it permits spinal growth and the later addition of fusion.

Tumors of the upper cervical spine are rare and represent less than 0.5 % of all spinal tumors. The types of tumor and the clinical presentation are as varied as the modalities used for treatment. The unique anatomy of the upper cervical spine with its high physical mobility means that biomechanical considerations and neighboring anatomical structures (e.g. vertebral artery, medulla oblongata, lower cranial nerves and pharynx) must be considered when creating a treatment plan. Finding a balance between complete tumor removal, the preservation and reestablishment of stability and function and the possible necessity for postoperative radiotherapy is of utmost importance and must be assessed on an individual basis. In this review paper some important points will be presented concerning the preparation of the patient, the planning of the operation and the surgical approach used in treating tumors of the craniocervical junction.

Purpose: We present the case of a 2-year-old patient with congenital scoliosis due to a lumbar hemivertebra. The current gold standard treatment of such an abnormality would be hemivertebra resection and short level posterior spinal fusion. However, due to the young age of the patient, we considered that application of a fusionless solution might offer advantages in terms of retaining normal segmental motion and the potential for growth., Methods: The incarcerated hemivertebra was resected and the facet joints of the neighbouring vertebrae were joined to create a new functional motion segment and correct the kyphoscoliotic deformity. Transpedicular screws were inserted on the convex side in L2 and L3 and a tension band was applied., Results: 16 years after the surgery, the patient was completely pain-free, motion of the lumbar spine was preserved and the physiological curvatures were maintained., Conclusion: To our knowledge a fusionless surgical solution for the treatment of a hemivertebra has never been described before. Although this is only a single case, the good result with a long follow-up suggests the technique is worthwhile considering when planning the treatment of a lumbar hemivertebra in very young children.

Purpose: The term "segmental instability" of the lumbar spine is not clearly defined, especially as it relates to degenerative spondylolisthesis (DS) and rotational translation (RT). We investigated whether facet joint effusion on conventional supine MRI indicated increased abnormal motion in DS and RT., Methods: 160 patients (119 female, 41 male, mean age 68.8 years, range 38.8-89.3 years) who had undergone decompression only or decompression with instrumented fusion for degenerative spondylolisthesis with different degrees of narrowing of the spinal canal were identified retrospectively from our spine surgery database. All had preoperative upright X-rays in AP and lateral views as well as supine MRI. The imaging studies were assessed for the following parameters: percent of slippage, absolute value of facet joint effusion, facet angles, degree of facet degeneration and spinal canal central narrowing, disc height, presence of facet cysts and the presence of rotational translation in the AP X-ray., Results: 40/160 patients showed no facet joint effusion, and in these the difference in the values for the % slip on upright X-ray and % slip on supine MRI was ≤3%. A further 12 patients also showed a difference ≤3%, but had some fluid in the joints (0.44 ± 0.38 mm). In 108 patients, the difference in the % slip measured on X-ray and on MRI was >3% (mean 10.6%, range 4-29%) and was associated with a mean facet effusion size of 2.15 ± 0.85 mm. The extent of effusion correlated significantly with the relative slippage difference between standing and supine positions (r = 0.64, p < 0.001), and the extent of the left/right difference in effusion was associated with the presence of rotational translation (RT 1.31 ± 0.8 mm vs. no-RT 0.23 ± 0.17 mm, p < 0.0001)., Conclusions: Facet joint effusion is clearly correlated with spontaneous reduction of the extent of slippage in the supine position compared to the upright position. Also, the greater the difference in right and left facet effusion, the higher the likelihood of having a RT. Future studies should assess whether analysis of facet joint effusion measured on routine MRI can help in decision-making regarding the optimal surgical treatment to be applied (decompression alone or combined with fusion).

Introduction: Clinical symptoms in lumbar degenerative spondylolisthesis (LDS) vary from predominantly radiating pain to severe mechanical low back pain. We examined whether the outcome of surgery for LDS varied depending on the predominant baseline symptom and the treatment administered [decompression with fusion (D&F) or decompression alone (D)]., Methods: 213 consecutive patients (69 ± 9 years; 155f, 58 m) participated. Inclusion criteria were LDS, maximum three affected levels, no previous surgery at the affected level, and D (N = 56) or D&F (N = 157) as the operative procedure. Pre-op and at 12 months' follow-up (FU), patients completed the multidimensional Core Outcome Measures Index (COMI) including 0-10 leg-pain (LP) and LBP scales. At 12 months' FU, patients rated global outcome which was then dichotomised into "good" and "poor"., Results: Pre-operatively, LBP and COMI scores were significantly worse (p < 0.05) in the D&F group than in the D group. The improvement in COMI at 12 months' FU was significantly greater for D&F than for D (p < 0.001) and was not influenced by the patient's declared "main problem" at baseline (back pain, leg pain, or neurological disturbances) (p > 0.05). There was a higher proportion (p = 0.01) of "good" outcomes at 12 months' FU in D&F (86%) than in D (70%). Multiple regression analysis, controlling for possible confounders, revealed treatment group to be the only significant predictor of outcome (adding fusion = better outcome)., Discussion: Our study indicated that LDS patients showed better patient-based outcome with instrumented fusion and decompression than with decompression alone, regardless of baseline symptoms. This may be due to the fact that the underlying slippage as the cause of the stenosis is better addressed with fusion.

Introduction: There is increasing awareness of the need for pedicle screw constructs in the treatment of spinal deformities in very young children. However, the long-term effects of pedicle screws on the immature spine are still unclear. We used a porcine model to analyze the morphological changes of the spinal canal and vertebral body in response to the placement of pedicle screws., Methods: 13 newborn pigs were operated on. Each pig received a single pedicle screw at the L2 level. After a tenfold increase in body weight (7 months later), the symmetry of the spinal canal and vertebral body was measured on CT scans of the investigational (L2) and control (L3) levels in terms of the angulations of the instrumented and non-instrumented halves of the vertebral body and spinal canal., Results: After 7 months, the normalised vertebral body angle had reduced on the non-screw side and increased on the screw side, indicating asymmetry in vertebral body growth in the axial plane. The difference was significant (p = 0.009). However, there was no significant difference between the screw and non-screw sides for the spinal canal angles at the L2 level at either the intraoperative or 7-month follow-up assessment (each p > 0.05)., Conclusions: Pedicle screws in the immature porcine spine have a significant effect on the development of the vertebral body. However, in the present study, no corresponding alteration of the morphology of the spinal canal was observed. Our results provide further support for the existing arguments in favour of pedicle screws when weighing up the many factors to be considered in creating a treatment plan for early onset scoliosis.

Destruction of the second cervical vertebra leads to a highly unstable situation. Reconstruction is difficult because the axis plays a central role in rotatory movements and has a unique function in redistributing axial loads. The axis transfers the axial load of the two lateral masses of the atlas to three surfaces on the third cervical vertebra: the two articular facets and the vertebral body. As reconstruction is difficult and the instability in this region is life threatening, pathological processes are often treated less radically compared to other areas of the cervical spine. However, this more moderate approach may result in worse outcomes and prognoses. This paper presents the development of a new implant (C2 prosthesis) and two illustrative cases describing the implementation of this new implant. The C2 prosthesis provides anterior support and therefore allows a more radical surgical approach.