Thoracolumbar junction orientation: its impact on thoracic kyphosis and sagittal alignment in both asymptomatic volunteers and symptomatic patients Abstract Purpose The thoracolumbar junction (TLJ) has not been explored in regard to its contribution to global sagittal alignment. This study aims to define novel sagittal parameters of the TLJ and to assess their roles within global sagittal alignment. Methods Included for cross-sectional, retrospective analysis were asymptomatic volunteers and symptomatic patients who had undergone operation for adult spinal deformity. Unique sagittal parameters of the TLJ were measured using the midline of the T12–L1 disk space: The TLJ orientation [TLJO; thoracolumbar tilt (TLT) and slope (TLS)]. Thoracic kyphosis (TK; T5–12), C7–S1 sagittal vertical axis (SVA), lumbar lordosis (LL; L1–S1), sacral slope (SS), pelvic tilt (PT), and pelvic incidence (PI) were measured. Continuous variables were compared using the independent t test. Pearson correlations examined relationships between the parameters in each group. The asymptomatic TK was calculated using the measurement of the asymptomatic volunteer’s TLJO by linear regression. Results One hundred fifteen asymptomatic volunteers and 127 symptomatic patients were included. Only LL among the lumbopelvic parameters correlated with TK (asymptomatic volunteers: r = − 0.42; symptomatic patients: r = − 0.40). All the pelvic parameters have no direct correlation with TK in both groups. TLJO had stronger correlation with TK [asymptomatic volunteers: r = − 0.68 (TLS), r = 0.41 (TLT); symptomatic patients: r = − 0.56 (TLS), r = 0.44 (TLT)] than the lumbopelvic parameters. TLS correlated with LL (asymptomatic volunteers: r = 0.78; symptomatic patients: r = 0.73). Most pelvic parameters correlated with TLJO except for PI. The asymptomatic TK was estimated by the derived formula: 20.847 + TLS × (− 1.198). Conclusion The TLJO integrates the status of the lumbopelvic sagittal parameters and simultaneously correlates with thoracic and global sagittal alignment. Graphic abstract These slides can be retrieved under Electronic Supplementary Material.

Providence nighttime bracing is effective in treatment for adolescent idiopathic scoliosis even in curves larger than 35° Abstract Summary of Background Data Since 2006, the Providence nighttime brace has been used for a conservative treatment for scoliosis. Previous studies comparing the outcomes after full-time bracing and nighttime bracing have reported a comparable outcome with curves < 35°. The aim of this study was to report the outcome after treatment in a cohort of adolescent idiopathic scoliosis patients, with curves between 20° and 45°. Methods One hundred and twenty-four patients with adolescent idiopathic scoliosis were included in this study with Cobb > 20°, remaining growth potential and no previous scoliosis treatment. Providence nighttime treatment, 8 h nightly, was initiated. Treatment was continued until 2 years post-menarcheal for females and until 6-month growth arrest for males. The patients were evaluated using standing radiographs during treatment and 6 and 12 months after termination of bracing. Results One hundred and twenty-four patients were included; 80 patients terminated brace treatment and were available for follow-up. Mean in-brace correction was 82%, and curve progression was observed in 9 patients. Brace treatment was success full in 89% of the patients, 88% of the patients braced with curves 20°–29°, 93% of the patients braced with 30°–39° and 77% of the patients braced with curves 40°–45°. Five of the 80 AIS patients were referred to surgery: 4 due to progression and 1 due to cosmetic concerns. Conclusions Providence nighttime braces are an effective treatment for adolescent idiopathic scoliosis patients. This study reports a success rate of 89%, and the results are comparable to full-time treatment with the Boston brace. In-brace correction is crucial in part-time bracing, and we recommend at least 70% curve correction, if part-time bracing should be considered. Graphical abstract These slides can be retrieved under Electronic Supplementary Material.

Comparison of a novel anterior-only approach and the conventional posterior–anterior approach for cervical facet dislocation: a retrospective study Abstract Objective The surgical treatment of lower cervical facet dislocation is controversial. The objective of this study was to compare the surgical trauma and clinical results of a novel anterior-only approach and with those of the conventional posterior–anterior approach to obtain an optimal method to treat lower cervical facet dislocation. Methods From January 2012 to December 2017, 93 patients with lower cervical facet dislocations were enrolled in the study and divided into two groups as follows: 63 conventional patients who enrolled between January 2014 and December 2017 were included in the anterior-only approach group, and 30 conventional patients who enrolled between January 2012 and December 2013 were included in the posterior–anterior approach group. For the anterior-only approach group, two reduction techniques, including Caspar pins kyphotic paramedian distraction and anterior facetectomy, were used in sequence if the former technique failed. The parameters were as follows: the operation time, the intraoperative blood loss, the number of fixed segments, the fusion rate, and the improvement in the ASIA grade and JOA score. Results All patients in the anterior-only approach group were successfully reduced by the two techniques. The mean operation time in the posterior–anterior approach group (274.0 ± 114.7 min) was significantly longer than that in the anterior-only approach group (88.6 ± 35.0 min) (p = 0.000). The mean blood loss during the surgery and the number of fixed segments in the posterior–anterior approach group (275.0 ± 183.2 ml; 1.4 ± 0.7, respectively) were significantly greater than those in the anterior-only approach group (92.5 ± 84.0 ml, p = 0.000; 1.2 ± 0.5, p = 0.030, respectively). A 100% fusion rate was observed in both groups after 12-month follow-up. There were no significant differences between the two groups regarding the improvement in the ASIA grade (p = 0.900) or JOA score (p = 0.717). Conclusions Compared with the conventional posterior–anterior approach, the novel anterior-only approach with two reduction techniques, including Caspar pins kyphotic paramedian distraction and anterior facetectomy, achieved a 100% reduction success rate and induced less surgical trauma, indicating that this method can be recommended as an alternative for lower cervical facet dislocation. Graphic abstract These slides can be retrieved under Electronic Supplementary Material.

Sagittal balance of the spine Abstract The static sagittal balance of the normal spine is a physiological alignment of the spine in the most efficient manner by the muscular forces. During gait, this balance is constantly thwarted by single-foot support. This analysis involves the study of parameters which are now well defined. The pelvic incidence is constant, and the sacral slope and the pelvic tilt are positional. The cervical parameters are the upper (O–C2) and lower cervical curvatures (C2–C7), the C7 slope, the spino-cranial angle and the vertical cervical offset. At the thoracic and lumbar level, they are, respectively, kyphosis and lordosis. The OD-HA (odontoid hip axis) angle is the most efficient parameter to analyse the global balance. The average values of these parameters are reported with the new 3D measurements by Le Huec et al. The relationship between these different parameters was analysed, and Roussouly proposed his classification of the different spine shape. Ageing makes it possible to show compensation mechanisms at three levels: spinal, pelvic and lower limbs. Understanding these different data allows for better planning of the surgical management of the patients. Global evaluation of the entire spine and the measurement of the aforementioned parameters allow to determine the extent of the correction to be performed during surgery. Taking these parameters into account also enables us to understand the complications involved in this type of surgery: transitional syndromes or junctional syndromes. Integration of these parameters into the study of gait is an area still under investigation. Graphic abstract These slides can be retrieved under Electronic Supplementary Material .

Treatment of bracing for adolescent idiopathic scoliosis patients: a meta-analysis Abstract Purpose A meta-analysis was conducted to compare the efficacy and safety of bracing and other treatments in adolescent idiopathic scoliosis (AIS) patients. Methods PubMed, Embase, and Cochrane Central Register of Controlled Trials were searched for randomized controlled trials that investigated bracing and other treatments for AIS. The Mantel–Haenszel method with fixed-effects or random-effects model was used to calculate the relative risks and 95% confidence intervals (CIs). The results of heterogeneity, sensitivity analysis, and publication bias were analyzed. Results Seven studies that met the eligibility criteria with 791 participants were included. The results of meta-analysis suggested significant differences between bracing and observation groups in successful outcomes [OR 3.58, 95% CI (1.92, 6.68), P < 0.0001; P for heterogeneity = 0.008, I2 = 65%], quality of life [MD = 2.13, 95% CI (0.51, 3.75), P = 0.01; P for heterogeneity = 0.89, I2 = 0%], and adverse events [OR 5.31, 95% CI (2.42, 11.66), P < 0.0001; P for heterogeneity = 0.78, I2 = 0%]. Conclusion The findings of this meta-analysis suggested that bracing is efficient and safe for the treatment of AIS. Graphic abstract These slides can be retrieved under Electronic Supplementary Material.

Is there any use? Validity of 4D rasterstereography compared to EOS 3D X-ray imaging in patients with degenerative disk disease Abstract Introduction Previous studies of 4D rasterstereography show a high intra- and interday reliability. However, only few studies validate rasterstereography to conventional X-ray imaging. We utilized EOS X-ray imaging system (EOS Imaging, Paris, France) for accurate 3D spinal modeling and compared the results to parameters obtained by 4D rasterstereography. The aim of the present study was to validate 4D rasterstereography in patients with degenerative disk disease (DDD). Materials and method Thirty-four individuals with DDD (female = 22 and male = 12) were included. EOS X-ray images were analyzed to determine spinal [lumbar lordosis (LL) and thoracic kyphosis (TK)] and pelvic parameters [pelvic obliquity (PO) and pelvic axial rotation (PR)]. Patients received 4D rasterstereographic measurements on the same day as EOS imaging. Parameters obtained by rasterstereography were compared to those obtained by EOS X-ray imaging. We used Bland and Altman’s test as well as Pearson test to validate rasterstereography. Additionally, we calculated interrater reliability of EOS X-ray analysis using the intraclass correlation coefficient (ICC). Results Our data showed only weak correlation between 4D rasterstereography and EOS X-ray imaging for spinal parameters (LL and TK). Pelvic parameters (PO and PR) showed no correlation. Interrater correlation reliability for EOS analysis was excellent (ICC > 0.8). Conclusion Our data suggest that rasterstereographic systems are no reliable substitute for X-ray-based imaging systems in patients with degenerative disk disease. EOS imaging was shown to provide reliable and accurate spinal modeling. Based on our results, rasterstereographic imaging should be used with caution for evaluating spinal and pelvic parameters in patients with DDD. Graphic abstract These slides can be retrieved under Electronic Supplementary Material.

Are respiratory disorders risk factors for troublesome low-back pain? A study of a general population cohort in Sweden Abstract Purpose A multi-morbidity perspective of troublesome low back pain (LBP) has been highlighted for example in relation to respiratory disorders. Our purpose was to investigate whether respiratory disorders are risk factors for reporting troublesome LBP in people with no or occasional LBP at baseline. Methods This prospective cohort study was based on the Stockholm Public Health Cohort 2006/2010. We included adults reporting no or occasional LBP the last 6 months at baseline (n = 17,177). Exposures were self-reported asthma and/or Chronic Obstructive Pulmonary Disease (COPD). Outcome was troublesome LBP defined as reporting LBP a couple of days per week or more often that restricted work capacity or hindered daily activities to some or to a high degree, the last 6 months. Binomial regression models were used to calculate risk ratios (RR) with 95% confidence intervals (95% CI). Results Adjusted results indicate that those suffering from asthma had a risk of troublesome LBP at follow-up (RR 1.29, 95% CI 0.92–1.81) as do those suffering from COPD (RR 2.0, 95% CI 1.13–3.56). If suffering from asthma and concurrent COPD the RR was 3.55 (95% CI 1.58–7.98). Conclusion Our findings indicate that suffering from asthma and/or COPD increases the risk of developing troublesome LBP, which highlights the importance to consider the overall health of people at risk of troublesome LBP and to take the multi-morbidity perspective into consideration. Future longitudinal studies are needed to confirm our findings. Graphic abstract These slides can be retrieved under Electronic Supplementary Material.

Endoplasmic reticulum stress regulates mechanical stress-induced ossification of posterior longitudinal ligament Abstract Purpose The pathogenesis of ossification of posterior longitudinal ligament (OPLL) is not completely clear. Previous study has confirmed a single-pass type I endoplasmic reticulum (ER) membrane protein kinase (PERK), which is a major transducer of the ER stress, participates in the process of OPLL in vitro. This study aimed to demonstrate the role of ER stress in mechanical stress (MS)-induced OPLL. Methods The posterior longitudinal ligaments were collected intraoperatively. The expression of ER stress markers in ligament tissue samples was compared between OPLL and non-OPLL patients in vivo. Ligament fibroblasts were isolated and cultured. Loaded by MS, the expression of ER stress markers in fibroblasts deriving from non-ossified areas of the ligament tissues from OPLL patients was detected. The influence of inhibition of ER stress on MS-induced OPLL and activation of mitogen-activated protein kinase (MAPK) pathways by MS was also investigated. Results We confirmed the ER stress markers were highly expressed in non-ossified areas of the ligament tissues from OPLL patients but could barely be detected in the ligaments from non-OPLL patients in vivo. We also found ER stress could be activated by MS during the process of OPLL in vitro. Moreover, inhibition of ER stress could hinder MS-induced OPLL and activation of MAPK signaling pathways by MS in vitro. Conclusion Activated ER stress was observed in OPLL patients both in vitro and in vivo. Mechanical stress could activate ER stress response in posterior longitudinal ligament fibroblasts and further promote OPLL in vitro. In this process, ER stress might work through the MAPK signaling pathways. Graphic abstract These slides can be retrieved under Electronic Supplementary Material.

Development of predictive models for all individual questions of SRS-22R after adult spinal deformity surgery: a step toward individualized medicine Abstract Purpose Health-related quality of life (HRQL) instruments are essential in value-driven health care, but patients often have more specific, personal priorities when seeking surgical care. The Scoliosis Research Society-22R (SRS-22R), an HRQL instrument for spinal deformity, provides summary scores spanning several health domains, but these may be difficult for patients to utilize in planning their specific care goals. Our objective was to create preoperative predictive models for responses to individual SRS-22R questions at 1 and 2 years after adult spinal deformity (ASD) surgery to facilitate precision surgical care. Methods Two prospective observational cohorts were queried for ASD patients with SRS-22R data at baseline and 1 and 2 years after surgery. In total, 150 covariates were used in training machine learning models, including demographics, surgical data and perioperative complications. Validation was accomplished via an 80%/20% data split for training and testing, respectively. Goodness of fit was measured using area under receiver operating characteristic (AUROC) curves. Results In total, 561 patients met inclusion criteria. The AUROC ranged from 56.5 to 86.9%, reflecting successful fits for most questions. SRS-22R questions regarding pain, disability and social and labor function were the most accurately predicted. Models were less sensitive to questions regarding general satisfaction, depression/anxiety and appearance. Conclusions To the best of our knowledge, this is the first study to explicitly model the prediction of individual answers to the SRS-22R questionnaire at 1 and 2 years after deformity surgery. The ability to predict individual question responses may prove useful in preoperative counseling in the age of individualized medicine. Graphic abstract These slides can be retrieved under Electronic Supplementary Material.

The incidence of myocardial infarction after lumbar spine surgery Abstract Purpose As the population continues to age, the number of lumbar spine surgeries continues to increase. While there are many complications associated with lumbar surgeries, a myocardial infarction (MI) is a particularly devastating one. This complication is of considerable importance with mortality rates of postoperative MI documented between 26.5 and 70%. This study aimed to determine the relationship between lumbar surgeries, preoperative diagnoses (risk factors), and myocardial infarction. Methods Data from the Humana database (PearlDiver) were analyzed from 2007 to 2016. Patients undergoing lumbar spine surgeries were identified and stratified based on procedural approach, patient demographics, and preoperative risk factors. Each group was analyzed to determine the incidence and relative risk. Chi-square analysis was used to determine the significance. Results A total of 105,505 patients who fit inclusion criteria were identified in the PearlDiver database between 2007 and 2016. A total of 644 patients (0.63%) experienced a postoperative myocardial infarction within 30 days of surgery. Patients undergoing fusion and non-fusion procedures showed significantly different rates of postoperative myocardial infarction (0.08% vs. 0.05%, p < 0.01). Male patients, older patients, and patients with a Charlson comorbidity index > 3 showed a considerable increase in incidence (p < 0.01). Furthermore, patients with preoperative risk factors (high cholesterol, obesity, depression, congestive heart failure, hypertension, and hypotension) exhibited risk ratios from 0.01 to 1.85 (p < 0.01). Conclusion Preoperative risk factors, patient demographics, and procedure type had a significant effect on the incidence of postoperative myocardial infarction. Graphic abstract These slides can be retrieved under Electronic Supplementary Material.