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Study Design: Cross-sectional survey., Objectives: Injury classifications are important tools to identify fracture patterns, guide treatment-decisions and aid to identify optimal treatment plans. The AO Spine-DGOU Osteoporotic Fracture (OF) classification system was developed, and the aim of this study was to assess the reliability of this new classification system., Methods: 23 Members of the AO Spine Knowledge Forum Trauma participated in the validation process. Participants were asked to rate 33 cases according to the OF classification at 2 time points, 4 weeks apart (assessment 1 and 2). The kappa statistic (κ) was calculated to assess inter-observer reliability and intra-rater reproducibility. The gold master key for each case was determined by approval of at least 5 out of 7 members of the DGOU., Results: A total of 1386 ratings (21 raters) were performed. The overall inter-rater agreement was moderate with a combined kappa statistic for the OF classification of 0.496 in assessment 1 and 0.482 in assessment 2. The combined percentage of correct ratings (compared to gold-standard) in assessment 1 was 71.4% and 67.4% in assessment 2. The average intra-rater reproducibility was substantial (κ = 0.74, median 0.76, range 0.55 to 1.00, SD 0.13) for the assessed fracture types., Conclusions: The assessed overall inter-rater reliability was moderate and substantial in some instances. The average intra-rater reproducibility is substantial. It seems that appropriate training of the classification system can enhance inter- and intra-rater reliability., Competing Interests: Declaration of conflicting interestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: The AO Spine-DGOU Injury Classification System was developed and funded by AO Spine through the AO Spine Knowledge Forum Trauma, a focused group of international spine trauma experts. AO Spine is a clinical division of the AO Foundation, which is an independent medically-guided not-for-profit organization. Individual authors of this manuscript have no disclosures to declare regarding the proposed article.

Study Design: Global Survey., Objective: To determine the accuracy, interobserver reliability, and intraobserver reproducibility of the AO Spine Upper Cervical Injury Classification System based on surgeons' AO Spine region of practice (Africa, Asia, Central/South America, Europe, Middle East, and North America)., Methods: A total of 275 AO Spine members assessed 25 upper cervical spine injuries and classified them according to the AO Spine Upper Cervical Injury Classification System. Reliability, reproducibility, and accuracy scores were obtained over two assessments administered at three-week intervals. Kappa coefficients (ƙ) determined the interobserver reliability and intraobserver reproducibility., Results: On both assessments, participants from Europe and North America had the highest classification accuracy, while participants from Africa and Central/South America had the lowest accuracy ( P < .0001). Participants from Africa (assessment 1 (AS1):ƙ = .487; AS2:0.491), Central/South America (AS1:ƙ = .513; AS2:0.511), and the Middle East (AS1:0.591; AS2: .599) achieved moderate reliability, while participants from North America (AS1:ƙ = .673; AS2:0.648) and Europe (AS1:ƙ = .682; AS2:0.681) achieved substantial reliability. Asian participants obtained substantial reliability on AS1 (ƙ = .632), but moderate reliability on AS2 (ƙ = .566). Although there was a large effect size, the low number of participants in certain regions did not provide adequate certainty that AO regions affected the likelihood of participants having excellent reproducibility ( P = .342)., Conclusions: The AO Spine Upper Cervical Injury Classification System can be applied with high accuracy, interobserver reliability, and intraobserver reproducibility. However, lower classification accuracy and reliability were found in regions of Africa and Central/South America, especially for severe atlas injuries (IIB and IIC) and atypical hangman's type fractures (IIIB injuries)., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Global cross-sectional survey., Objective: To develop and refine the techniques for web-based international validation of fracture classification systems., Methods: A live webinar was organized in 2018 for validation of the AO Spine Subaxial Injury Classification System, consisting of 35 unique computed tomography (CT) scans and key images with subaxial spine injuries. Interobserver reliability and intraobserver reproducibility was calculated for injury morphology, subtype, and facet injury according to the classification system. Based on the experiences from this webinar and incorporating rater feedback, adjustments were made in the organization and techniques used and in 2020 a repeat validation webinar was performed, evaluating images of 41 unique subaxial spine injuries., Results: In the 2018 session, the AO Spine Subaxial Injury Classification System demonstrated fair interobserver reliability for fracture subtype (κ = 0.35) and moderate reliability for fracture morphology and facet injury (κ=0.45, 0.43, respectively). However, in 2020, the interobserver reliability for fracture morphology (κ = 0.87) and fracture subtype (κ = 0.80) was excellent, while facet injury was substantial (κ = 0.74). Intraobserver reproducibility for injury morphology (κ =0.49) and injury subtype/facet injury were moderate (κ = 0.42) in 2018. In 2020, fracture morphology and subtype reproducibility were excellent (κ =0.85, 0.88, respectively) while reproducibility for facet injuries was substantial (κ = 0.76)., Conclusion: With optimized webinar-based validation techniques, the AO Spine Subaxial Injury Classification System demonstrated vast improvements in intraobserver reproducibility and interobserver reliability. Stringent fracture classification methodology is integral in obtaining accurate classification results., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Global cross-sectional survey., Objective: To explore the influence of geographic region on the AO Spine Sacral Classification System., Methods: A total of 158 AO Spine and AO Trauma members from 6 AO world regions (Africa, Asia, Europe, Latin and South America, Middle East, and North America) participated in a live webinar to assess the reliability, reproducibility, and accuracy of classifying sacral fractures using the AO Spine Sacral Classification System. This evaluation was performed with 26 cases presented in randomized order on 2 occasions 3 weeks apart., Results: A total of 8320 case assessments were performed. All regions demonstrated excellent intraobserver reproducibility for fracture morphology. Respondents from Europe (k = .80) and North America (k = .86) achieved excellent reproducibility for fracture subtype while respondents from all other regions displayed substantial reproducibility. All regions demonstrated at minimum substantial interobserver reliability for fracture morphology and subtype. Each region demonstrated >90% accuracy in classifying fracture morphology and >80% accuracy in fracture subtype compared to the gold standard. Type C morphology (p 2 = .0000) and A3 (p 1 = .0280), B2 (p 1 = .0015), C0 (p 1 = .0085), and C2 (p 1 =.0016, p 2 =.0000) subtypes showed significant regional disparity in classification accuracy (p 1 = Assessment 1, p 2 = Assessment 2). Respondents from Asia (except in A3) and the combined group of North, Latin, and South America had accuracy percentages below the combined mean, whereas respondents from Europe consistently scored above the mean., Conclusions: In a global validation study of the AO Spine Sacral Classification System, substantial reliability of both fracture morphology and subtype classification was found across all geographic regions.

Study Design: Retrospective Cohort Study., Objective: To determine how historical management of thoracolumbar spine injuries compares to the recently proposed AO Spine Thoracolumbar Injury Classification System treatment algorithm., Summary of Background Data: Classifications of the thoracolumbar spine are not uncommon. The frequent advent of new classifications is typically due to previous classifications being primarily descriptive or unreliable. Thus, AO Spine created a classification with an associated treatment algorithm to guide injury classification and management., Methods: Thoracolumbar spine injuries were retrospectively identified from a prospectively collected spine trauma database at a single, urban, academic medical center during the years 2006 to 2021. Each injury was classified and assigned points based on the AO Spine Thoracolumbar Injury Classification System injury severity score. Patients were grouped into scores of 3 or less (preferred initial conservative treatment) and greater than 6 (preferred initial surgical intervention). Either operative or non-operative treatment was considered appropriate for injury severity scores of 4 or 5., Results: A total of 815 patients (TL AOSIS 0-3: 486, TL AOSIS 4-5: 150, TL AOSIS 6+: 179) met inclusion status. Injury severity scores of 0-3 were more likely to undergo non-operative management compared to scores of 4-5 or 6+ (99.0% vs. 74.7% vs. 13.4%, P <0.001). Thus, guideline congruent treatment was 99.0%, 100%, and 86.6%, respectively ( P <0.001). Most injuries determined to be a 4 or 5 were treated non-operatively (74.7%). Based on the treatment algorithm, 97.5% of patients who received operative treatment and 96.1% who received non-operative treatment were managed in accordance with the algorithm. Of the 29 patients who did not receive algorithm congruent treatment, 5 (17.2%) were treated surgically., Conclusions: A retrospective review of thoracolumbar spine injuries at our urban academic medical center identified that patients are historically treated in accordance with the proposed AO Spine Thoracolumbar Injury Classification System treatment algorithm., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

The Arbeitsgemeinschaft fur Osteosynthese fragen Spine Sacral Injury Classification hierarchically separates fractures based on their injury severity with A-type fractures representing less severe injuries and C-type fractures representing the most severe fracture types. C0 fractures represent moderately severe injuries and have historically been referred to as nondisplaced "U-type" fractures. Injury management of these fractures can be controversial. Therefore, the purpose of this narrative review is to first discuss the Arbeitsgemeinschaft fur Osteosynthese fragen Spine Sacral Injury Classification System and describe the different fracture types and classification modifiers, with particular emphasis on C0 fracture types. The narrative review will then focus on the epidemiology and etiology of C0 fractures with subsequent discussion focused on the clinical presentation for patients with these injuries. Next, we will describe the imaging findings associated with these injuries and discuss the injury management of these injuries with particular emphasis on operative management. Finally, we will outline the outcomes and complications that can be expected during the treatment of these injuries., Competing Interests: Dr Schroeder has received funds to travel from AO Spine and Medtronic. Dr Vaccaro has consulted or has done independent contracting for DePuy, Medtronic, Stryker Spine, Globus, Stout Medical, Gerson Lehrman Group, Guidepoint Global, Medacorp, Innovative Surgical Design, Orthobullets, Ellipse, and Vertex. He has also served on the scientific advisory board/board of directors/committees for Flagship Surgical, AO Spine, Innovative Surgical Design, and Association of Collaborative Spine Research. Dr Vaccaro has received royalty payments from Medtronic, Stryker Spine, Globus, Aesculap, Thieme, Jaypee, Elsevier, and Taylor Francis/Hodder and Stoughton. He has stock/stock option ownership interests in Replication Medica, Globus, Paradigm Spine, Stout Medical, Progressive Spinal Technologies, Advanced Spinal Intellectual Properties, Spine Medica, Computational Biodynamics, Spinology, In Vivo, Flagship Surgical, Cytonics, Bonovo Orthopaedics, Electrocore, Gamma Spine, Location Based Intelligence, FlowPharma, R.S.I., Rothman Institute and Related Properties, Innovative Surgical Design, and Avaz Surgical. In addition, Dr Vaccaro has also provided expert testimony. He has also served as deputy editor/editor of Clinical Spine Surgery. The remaining authors declare no conflict of interest., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc.)

Purpose: To validate the AO Spine Subaxial Injury Classification System with participants of various experience levels, subspecialties, and geographic regions., Methods: A live webinar was organized in 2020 for validation of the AO Spine Subaxial Injury Classification System. The validation consisted of 41 unique subaxial cervical spine injuries with associated computed tomography scans and key images. Intraobserver reproducibility and interobserver reliability of the AO Spine Subaxial Injury Classification System were calculated for injury morphology, injury subtype, and facet injury. The reliability and reproducibility of the classification system were categorized as slight (ƙ = 0-0.20), fair (ƙ = 0.21-0.40), moderate (ƙ = 0.41-0.60), substantial (ƙ = 0.61-0.80), or excellent (ƙ = > 0.80) as determined by the Landis and Koch classification., Results: A total of 203 AO Spine members participated in the AO Spine Subaxial Injury Classification System validation. The percent of participants accurately classifying each injury was over 90% for fracture morphology and fracture subtype on both assessments. The interobserver reliability for fracture morphology was excellent (ƙ = 0.87), while fracture subtype (ƙ = 0.80) and facet injury were substantial (ƙ = 0.74). The intraobserver reproducibility for fracture morphology and subtype were excellent (ƙ = 0.85, 0.88, respectively), while reproducibility for facet injuries was substantial (ƙ = 0.76)., Conclusion: The AO Spine Subaxial Injury Classification System demonstrated excellent interobserver reliability and intraobserver reproducibility for fracture morphology, substantial reliability and reproducibility for facet injuries, and excellent reproducibility with substantial reliability for injury subtype., (© 2022. The Author(s).)

Background Context: Prior upper cervical spine injury classification systems have focused on injuries to the craniocervical junction (CCJ), atlas, and dens independently. However, no previous system has classified upper cervical spine injuries using a comprehensive system incorporating all injuries from the occiput to the C2-3 joint., Purpose: To (1) determine the accuracy of experts at correctly classifying upper cervical spine injuries based on the recently proposed AO Spine Upper Cervical Injury Classification System (2) to determine their interobserver reliability and (3) identify the intraobserver reproducibility of the experts., Study Design/setting: International Multi-Center Survey., Patient Sample: A survey of international spine surgeons on 29 unique upper cervical spine injuries., Outcome Measures: Classification accuracy, interobserver reliability, intraobserver reproducibility., Methods: Thirteen international AO Spine Knowledge Forum Trauma members participated in two live webinar-based classifications of 29 upper cervical spine injuries presented in random order, four weeks apart. Percent agreement with the gold-standard and kappa coefficients (ƙ) were calculated to determine the interobserver reliability and intraobserver reproducibility., Results: Raters demonstrated 80.8% and 82.7% accuracy with identification of the injury classification (combined location and type) on the first and second assessment, respectively. Injury classification intraobserver reproducibility was excellent (mean, [range] ƙ=0.82 [0.58-1.00]). Excellent interobserver reliability was found for injury location (ƙ = 0.922 and ƙ=0.912) on both assessments, while injury type was substantial (ƙ=0.689 and 0.699) on both assessments. This correlated to a substantial overall interobserver reliability (ƙ=0.729 and 0.732)., Conclusions: Early phase validation demonstrated classification of upper cervical spine injuries using the AO Spine Upper Cervical Injury Classification System to be accurate, reliable, and reproducible. Greater than 80% accuracy was detected for injury classification. The intraobserver reproducibility was excellent, while the interobserver reliability was substantial., Competing Interests: Declarations of competing interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. This study was organized and funded by AO Spine through the AO Spine Knowledge Forum Trauma, a focused group of international Trauma experts. AO Spine is a clinical division of the AO Foundation, which is an independent medically-guided not-for-profit organization. Study support was provided directly through the AO Spine Research Department., (Copyright © 2022 AO Foundation, AO Spine, AO Network Clinical Research. Published by Elsevier Inc. All rights reserved.)

Study Design: Global cross-sectional survey., Objective: To determine the classification accuracy, interobserver reliability, and intraobserver reproducibility of the AO Spine Upper Cervical Injury Classification System based on an international group of AO Spine members., Summary of Background Data: Previous upper cervical spine injury classifications have primarily been descriptive without incorporating a hierarchical injury progression within the classification system. Further, upper cervical spine injury classifications have focused on distinct anatomical segments within the upper cervical spine. The AO Spine Upper Cervical Injury Classification System incorporates all injuries of the upper cervical spine into a single classification system focused on a hierarchical progression from isolated bony injuries (type A) to fracture dislocations (type C)., Methods: A total of 275 AO Spine members participated in a validation aimed at classifying 25 upper cervical spine injuries through computed tomography scans according to the AO Spine Upper Cervical Classification System. The validation occurred on two separate occasions, three weeks apart. Descriptive statistics for percent agreement with the gold-standard were calculated and the Pearson χ 2 test evaluated significance between validation groups. Kappa coefficients (κ) determined the interobserver reliability and intraobserver reproducibility., Results: The accuracy of AO Spine members to appropriately classify upper cervical spine injuries was 79.7% on assessment 1 (AS1) and 78.7% on assessment 2 (AS2). The overall intraobserver reproducibility was substantial (κ=0.70), while the overall interobserver reliability for AS1 and AS2 was substantial (κ=0.63 and κ=0.61, respectively). Injury location had higher interobserver reliability (AS1: κ = 0.85 and AS2: κ=0.83) than the injury type (AS1: κ=0.59 and AS2: 0.57) on both assessments., Conclusion: The global validation of the AO Spine Upper Cervical Injury Classification System demonstrated substantial interobserver agreement and intraobserver reproducibility. These results support the universal applicability of the AO Spine Upper Cervical Injury Classification System., Level of Evidence: 4., Competing Interests: The authors report no conflicts of interest., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc.)

Study Design: Narrative review., Objectives: Multiple classifications have been proposed for sacral fractures since the last century. While initial classifications focussed on vertical and transverse fractures, the recent fracture classifications encompass all injury patterns. In 1990, Isler classified unilateral vertical sacral fractures based on its potential influence on lumbo-sacral joint (LSJ) stability., Methods: We re-visited the original description of Isler's classification of sacral fractures and subsequent studies that have cited it. We will further describe basic LSJ anatomy, evolution of sacral classification systems and the use of Isler's classification system as it relates to LSJ instability and chronic low back pain., Results: Isler described a subset of unilateral vertical sacral fractures where the fracture line exited medial or through the L5-S1 facet joint, based on radiographic review of 193 sacral fractures (incidence -3.5%). He stated that such a fracture should be recognised as it can impede hemi-pelvis reduction and can result in late LSJ instability. The article has been cited in 106 studies and only a few studies have described the incidence of this variant. Nevertheless, the injury is considered as an indication for surgical fixation., Conclusion: A review of various classifications indicates that sacral fractures have three important bio-mechanical implications, namely, pelvic ring continuity (vertical fractures), spino-pelvic alignment (high transverse fractures) and lumbo-sacral joint integrity (Isler's fractures). Though there is a universal recognition of Isler's fractures and its impact on LSJ integrity, there is a lack of clinical and bio-mechanical evidence regarding the concept of instability caused by a unilateral Isler fracture.

Purpose: To assess the accuracy and reliability of the AO Spine Upper Cervical Injury Classification System based on a surgeons' work setting and trauma center affiliation., Methods: A total of 275 AO Spine members participated in a validation of 25 upper cervical spine injuries, which were evaluated by computed tomography (CT) scans. Each participant was grouped based on their work setting (academic, hospital-employed, or private practice) and their trauma center affiliation (Level I, Level II or III, and Level IV or no trauma center). The classification accuracy was calculated as percent of correct classifications, while interobserver reliability, and intraobserver reproducibility were evaluated based on Fleiss' Kappa coefficient., Results: The overall classification accuracy for surgeons affiliated with a level I trauma center was significantly greater than participants affiliated with a level II/III center or a level IV/no trauma center on assessment one (p 1 <0.0001) and two (p 2 = 0.0003). On both assessments, surgeons affiliated with a level I or a level II/III trauma center were significantly more accurate at identifying IIIB injury types (p 1 = 0.0007; p 2 = 0.0064). Academic surgeons and hospital employed surgeons were significantly more likely to correctly classify type IIIB injuries on assessment one (p 1 = 0.0146) and two (p 2 = 0.0015). When evaluating classification reliability, the largest differences between work settings and trauma center affiliations was identified in type IIIB injuries., Conclusion: Type B injuries are the most difficult injury type to correctly classify. They are classified with greater reliability and classification accuracy when evaluated by academic surgeons, hospital-employed surgeons, and surgeons associated with higher-level trauma centers (I or II/III)., Competing Interests: Declaration of conflict of interest This study was organized and funded by AO Spine through the AO Spine Knowledge Forum Trauma, a focused group of international Trauma experts. AO Spine is a clinical division of the AO Foundation, which is an independent medically guided not-for-profit organization. Study support was provided directly through the AO Spine Research Department., (Copyright © 2022 AO Foundation. Published by Elsevier Ltd.. All rights reserved.)

Background: This study aims to analyze the incidence and outcomes of bicycle-related injuries in hospitalized patients in The Netherlands., Methods: Bicycle accidents resulting in hospitalization in a level-I trauma center in The Netherlands between 2007 and 2017 were retrospectively identified. We subcategorized data of patients involved in a regular bicycle, race bike, off-road bike or e-bike accident. The primary outcomes were mortality rate and incidence of multitrauma. Secondary outcomes were differences between bicycle subcategories. Independent risk factors were identified using multivariable logistic regression. All variables with a p value < 0.20 in univariable analysis were entered in multivariable analysis., Results: We identified 1986 patients. The mortality rate after emergency room admission was 5.7%, and 41.0% were multitraumas. A higher age, multitrauma and cerebral haemorrhages were independent risk factors for in hospital mortality. Independent risk factors found for multitrauma were a higher age, two-sided trauma, e-bike accidents and cerebral haemorrhage., Conclusion: Bicycle accidents resulting in hospitalization have a high mortality rate. Furthermore, a high incidence of multitrauma, fractures and cerebral haemorrhages were found. Considering the increasing incidence of bicycle accident victims needing hospital admission, new and more efficient prevention strategies are essential.

To induce osteogenicity in bone graft substitutes, plasmid-based expression of BMP-2 (pBMP-2) has been successfully applied in gene activated matrices based on alginate polymer constructs. Here, we investigated whether cell seeding is necessary for non-viral BMP-2 gene expression in vivo. Furthermore, to gain insight in the role of BMP-producing cells, we compared inclusion of bone progenitor cells with non-osteogenic target cells in gene delivery constructs. Plasmid DNA encoding GFP (pGFP) was used to trace transfection of host tissue cells and seeded cells in a rat model. Transgene expression was followed in both cell-free alginate-ceramic constructs as well as constructs seeded with syngeneic fibroblasts or multipotent mesenchymal stromal cells (MSCs). Titration of pGFP revealed that the highest pGFP dose resulted in frequent presence of positive host cells in the constructs. Both cell-loaded groups were associated with transgene expression, most effectively in the MSC-loaded constructs. Subsequently, we investigated effectiveness of cell-free and cell-loaded alginate-ceramic constructs with pBMP-2 to induce bone formation. Local BMP-2 production was found in all groups containing BMP-2 plasmid DNA, and was most pronounced in the groups with MSCs transfected with high concentration pBMP-2. Bone formation was only apparent in the recombinant protein BMP-2 group. In conclusion, we show that non-viral gene delivery of BMP-2 is a potentially effective way to induce transgene expression in vivo, both in cell-seeded as well as cell-free conditions. However, alginate-based gene delivery of BMP-2 to host cells or seeded cells did not result in protein levels adequate for bone formation in this setting, calling for more reliable scaffold compatible transfection methods., Competing Interests: The authors have declared that no competing interests exist.

Study Design: A prospective multicenter cohort study., Objective: To assess the clinical accuracy of six commonly cited prognostic scoring systems for patients with spinal metastases., Summary of Background Data: There are presently several available methods for the estimation of prognosis in metastatic spinal disease, but none are universally accepted by surgeons for clinical use. These scoring systems have not been rigorously tested and validated in large datasets to see if they are reliable enough to inform day-to-day patient management decisions. We tested these scoring systems in a large cohort of patients. A total of 1469 patients were recruited into a secure internet database, and prospectively collected data were analyzed to assess the accuracy of published prognostic scoring systems., Methods: We assessed six prognostic scoring systems, described by the first authors Tomita, Tokuhashi, Bauer, van der Linden, Rades, and Bollen. Kaplan-Meier survival estimates were created for different patient subgroups as described in the original publications. Harrell's C-statistic was calculated for the survival estimates, to assess the concordance between estimated and actual survival., Results: All the prognostic scoring systems tested were able to categorize patients into separate prognostic groups with different overall survivals. However none of the scores were able to achieve "good concordance" as assessed by Harrell's C-statistic. The score of Bollen and colleagues was found to be the most accurate, with a Harrell's C-statistic of 0.66., Conclusion: No prognostic scoring system was found to have a good predictive value. The scores of Bollen and Tomita were the most effective with Harrell's C-statistic of 0.66 and 0.65, respectively. Prognostic scoring systems are calculated using data from previous years, and are subject to inaccuracies as treatments advance in the interim. We suggest that other methods of assessing prognosis should be explored, such as prognostic risk calculation., Level of Evidence: 3.

Background: Indications for surgery for symptomatic spinal metastases have become better defined in recent years, and suitable outcome measures have been established against a changing backdrop of patient characteristics, tumor behavior, and oncologic treatments. Nonetheless, variations still exist in the local management of patients with spinal metastases. In this study, we aimed to review global trends and habits in the surgical treatment of symptomatic spinal metastases, and to examine how these have changed over the last 25 years., Methods: In this cohort study of consecutive patients undergoing surgery for symptomatic spinal metastases, data were collected using a secure Internet database from 22 centers across 3 continents. All patients were invited to participate in the study, except those unable or unwilling to give consent., Results: There was a higher incidence of colonic, liver, and lung carcinoma metastases in Asian countries, and more frequent presentation of breast, prostate, melanoma metastases in the West. Trends in surgical technique were broadly similar across the centers. Overall survival rates after surgery were 53% at 1 year, 31% at 2 years, and 10% at 5 years after surgery (standard error 0.013 for all). Survival improved over successive time periods, with longer survival in patients who underwent surgery in 2011-2016 compared with those who underwent surgery in earlier time periods., Conclusions: Surgical habits have been fairly consistent among countries worldwide and over time. However, patient survival has improved in later years, perhaps due to medical advances in the treatment of cancer, improved patient selection, and operating earlier in the course of disease., (Copyright © 2018 Elsevier Inc. All rights reserved.)

This article focuses on patient-reported and clinician-reported outcome measures in spine trauma care. The measurement of the quality of care and functional and health-related quality of life outcomes of spine trauma patients has become increasingly important. However, no outcome instrument is specifically designed, validated, or universally adapted for this specific patient population. Issues specific to spinal trauma patients may not be adequately addressed by the instruments that are currently used in the literature and the daily clinical practice. The AOSpine Knowledge Forum Trauma initiated a project to develop and validate such instruments for spine trauma patients. To reflect the different perspectives of patients and the treating surgeons, 2 separate tools are being developed: the Patient Reported Outcome Spine Trauma (AOSpine PROST) and Clinician Reported Outcome Spine Trauma (AOSpine CROST). These tools hold promise, as useful instruments to measure the outcomes of spine trauma patients with and without neurological deficit, making it more feasible for clinical use as well. Treating surgeons around the world are encouraged to use the AOSpine PROST and AOSpine CROST in daily clinical practice and for research purposes to create and contribute to evidence-based and patient-centered care. Using the same outcome measures that are specifically developed and validated for traumatic spine injuries will allow us to compare the outcomes of various treatments in a valid and reproducible fashion. This contributes to a reduction of the ongoing controversies and providing the best treatments for our patients.

Fractures of the odontoid process of C2 have become increasingly prevalent in the aging population and are typically associated with a high incidence of morbidity. Dens fractures comprise the majority of all cervical fractures in patients older than 80 years and remain the most common cervical fracture pattern in all geriatric patients. Type II odontoid fractures have been associated with limited healing potential, and both nonoperative and operative management are associated with high mortality rates. Historically, there has been some debate in the literature with regards to optimal management strategies to maximize outcomes in geriatric patients. Recent, high-quality evidence has indicated that surgical treatment of type II odontoid fractures in elderly patients is associated with improvements in both short- and long-term mortality. Additionally, surgical intervention has been shown to improve functional outcomes when compared with nonsurgical treatment. Factors to consider before surgery for geriatric type II odontoid fractures include associated comorbidities and the safety of general anesthesia administration. With appropriate measures of patient selection, surgery can provide an efficacious option for geriatric patients with type II odontoid fractures. We recommend surgical intervention via a posterior C1-C2 arthrodesis for geriatric type II odontoid fractures, provided that the surgery itself does not represent an unreasonable risk for mortality.

Although less common than other musculoskeletal injuries, spinal trauma may lead to significantly more disability and costs. During the last 2 decades there was substantial improvement in our understanding of the basic patterns of spinal fractures leading to more reliable classification and injury severity assessment systems but also rapid developments in surgical techniques. Despite these advancements, there remain unresolved issues concerning the management of these injuries. At this moment there is persistent controversy within the spinal trauma community, which can be grouped under 6 headings. First of all there is still no unanimity on the role and timing of medical and surgical interventions for patients with associated neurologic injury. The same is also true for type and timing of surgical intervention in multiply injured patients. In some common injury types like odontoid fractures and burst type (A3-A4) fractures in thoracolumbar spine, there is wide variation in practice between operative versus nonoperative management without clear reasons. Also, the role of different surgical approaches and techniques in certain injury types are not clarified yet. Methods of nonoperative management and care of elderly patients with concurrent complex disorders are also areas where there is no consensus. In this overview article the main reasons for these controversies are reviewed and the possible ways for resolutions are discussed.

Osteoporotic vertebral fractures constitute at least 50% of the osteoporotic fractures that happen worldwide. Occurrence of osteoporotic fractures make the elderly patient susceptible for further fractures and increases the morbidity due to kyphosis and pain; the mortality risk is also increased in these patients. Most fractures occur in the thoracic and thoracolumbar region and are often stable. Different descriptive and prognostic classification systems have been described, but none are universally accepted. Radiographs, computed tomography, and magnetic resonance imaging are useful in imaging the fracture and evaluating the bone density. In acute stages, the fractures are well treated with conservative measures including short bed rest, analgesics, bracing, and exercises. Although most fractures heal well, up to 30% of fractures can develop painful nonunion, progressive kyphosis, and neurological deficit. For patients who develop severe pain not responding to nonoperative measures and painful nonunion, percutaneous cement augmentation procedures including vertebroplasty or kyphoplasty have been suggested. For fractures with severe collapse and that lead to neurological deficit and increasing kyphosis, instrumented stabilization is advised. Prevention and management of osteoporosis is the key element in the management of osteoporotic fractures in the elderly. Guidelines for essential adequate dietary and supplemental calcium and vitamin D, and antiosteoporotic medications have been described.

Numerous classification systems for subaxial and thoracolumbar spine injuries were proposed in the past with the attempt to facilitate communication between physicians. The AO-Magerl, thoracolumbar system, and Subaxial Cervical Spine Injury Classification systems are all well known, but did not achieve universal international adoption. A group of international experienced spine trauma surgeons were brought together by AOSpine with the goal to develop a comprehensive yet simple classification system for spinal trauma. This article is a synopsis of the proposed subaxial and thoracolumbar classification systems. In several studies, this classification system was developed using an iterative consensus process among the clinical experts in sufficient number and quality of DICOM images of real cases searching for meaningful and reproducible patterns. Both systems are based on 3 injury morphology types: compression injuries (A), tension band injuries (B), and translational injuries (C) with a total of 9 subgroups. In the subaxial cervical spine 4 additional subtypes for facet injuries exist. Patient-specific modifiers and neurologic status were also included to aid surgeons in therapeutic decision making. The proposed classification systems for subaxial and thoracolumbar injuries showed substantial intraobserver and interobserver reliability (κ = 0.64-0.85) for grading fracture type. Grading for the subtypes varied considerably due to the low frequency of certain injury subtypes among other reasons. In summary, the AOSpine thoracolumbar and subaxial cervical spine injury systems show substantial reliability, thus being valuable tools for clinical and research purposes.

Introduction: Spinal ankylosing disorders encompass ankylosing spondylitis (AS), disseminated hyperostosis of the spine, and end-stage spondylosis. All these result in a stiffened and frequently deformed spinal column. This makes the spinal column highly susceptible to severe injuries that are commonly associated with unfavorable outcomes. Improved understanding of the underlying disease processes and clinical comorbidities may alter the poor injury related morbidity and mortality outcomes., Methods: A systematic review of the MEDLINE and PubMed databases was performed using the following key words to identify articles published between 2001 and 2016: "ankylosing spondylitis," "epidemiology," "DISH," "treatment," "outcome," and/or "fracture." Articles were read for data on methodology (retrospective vs. prospective), type of treatment, number of patients, mean patient age, and mean follow-up., Results: Twenty-one identified articles were analyzed. Average age was 63.4 years. Most patients were men. Ground level fall or low energy trauma caused most injuries. Diagnosis was delayed in 15%-41% cases. Hyperextension fracture patterns were most common. Cervical spine fractures were more common than thoracolumbar fractures, with the highest prevalence between C5 and C7. Neurologic deficits were encountered in 21%-100% of patients. Operative fixation and fusion were performed in 40%-100% of patients. Mortality was reported between 0% and 32% at 1 year postinjury. Complications were encountered in 84% of patients, mostly in the form of pneumonia, respiratory failure, and pseudoarthrosis. Neurologic deterioration has been reported in 16% of patients. Fusion was successful in 87%-100% of patients. Neurologic deficits improved in function in 6%-66% at the final follow-up., Conclusions: Because of the stiffening of the spinal column, patients with spinal ankylosing disorders are preferably evaluated for spinal fractures and ligamentous injuries after even trivial trauma. Spinal injuries in patients with AS are difficult to diagnose on plain radiographs; computed tomography and magnetic resonance imaging are recommended instead. The entire spine should be scanned for multilevel involvement. Although osteoporosis makes fixation of spine implants a significant concern, the literature has reported that most patients with AS treated surgically had good outcomes. Numerous studies have reported risks associated with conservative management.

Introduction: Cervical spine injury classification systems should be simple, easy to relate and remember, reliable guide for surgical planning, and predictor of outcome in clinical settings. We investigated whether the AOSpine subaxial cervical spine classification system predicted injury severity and neurologic outcome., Material and Methods: We analyzed the relevant clinical, imaging, management, and American Spinal Injury Association (ASIA) impairment scale (AIS) grade conversion of 92 AIS grades A-C patients with cervical spine injury. We correlated morphology class with age, injury severity score (ISS), follow-up ASIA motor score (AMS), intramedullary lesion length (IMLL), and AIS grade conversion at 6 months after injury., Results: The mean age of patients was 39.3 years, 83 were men, and 69 were injured during an automobile accident or after a fall. The AOSpine class was A4 in 8, B2 in 5, B2A4 in 16, B3 in 19, and C in 44 patients. The mean ISS was 29.7 and AMS was 17.1. AIS grade was A in 48, B in 25, and C in 19 patients. Mean IMLL on postoperative magnetic resonance imaging was 72 mm: A4 = 68.1; B2A4 = 86.5; B2 = 59.3; B3 = 46.8; and C = 79.9. At a mean follow-up of 6 months, the mean AMS was 39.6. Compared to patients with class B3 injuries, those with class C injuries were significantly younger (P < 0.0001), had longer IMLL (P < 0.002), and were less likely to have AIS grade conversion to a better grade (P < 0.02)., Conclusions: The AOSpine subaxial cervical spine injury classification system successfully predicted injury severity (longer IMLL) and chances of neurologic recovery (AIS grade conversion) across different class subtypes.

Study Design: Reliability and agreement study, retrospective case series., Objective: To develop a widely accepted, comprehensive yet simple classification system with clinically acceptable intra- and interobserver reliability for use in both clinical practice and research., Summary of Background Data: Although the Magerl classification and thoracolumbar injury classification system (TLICS) are both well-known schemes to describe thoracolumbar (TL) fractures, no TL injury classification system has achieved universal international adoption. This lack of consensus limits communication between clinicians and researchers complicating the study of these injuries and the development of treatment algorithms., Methods: A simple and reproducible classification system of TL injuries was developed using a structured international consensus process. This classification system consists of a morphologic classification of the fracture, a grading system for the neurological status, and description of relevant patient-specific modifiers. Forty cases with a broad range of injuries were classified independently twice by group members 1 month apart and analyzed for classification reliability using the Kappa coefficient (κ)., Results: The morphologic classification is based on 3 main injury patterns: type A (compression), type B (tension band disruption), and type C (displacement/translation) injuries. Reliability in the identification of a morphologic injury type was substantial (κ= 0.72)., Conclusion: The AOSpine TL injury classification system is clinically relevant according to the consensus agreement of our international team of spine trauma experts. Final evaluation data showed reasonable reliability and accuracy, but further clinical validation of the proposed system requires prospective observational data collection documenting use of the classification system, therapeutic decision making, and clinical follow-up evaluation by a large number of surgeons from different countries.

Purpose: Many systematic reviews have been published on surgical interventions for low back disorders. The objective of this overview was to evaluate the available evidence from systematic reviews on the effectiveness of surgical interventions for disc herniation, spondylolisthesis, stenosis, and degenerative disc disease (DDD). An earlier version of this review was published in 2006 and since then, many new, better quality reviews have been published., Methods: A comprehensive search was performed in the Cochrane database of systematic reviews (CDSR), database of reviews of effectiveness (DARE) and Pubmed. Two reviewers independently performed the selection of studies, risk of bias assessment, and data extraction. Included are Cochrane reviews and non-Cochrane systematic reviews published in peer-reviewed journals. The following conditions were included: disc herniation, spondylolisthesis, and DDD with or without spinal stenosis. The following comparisons were evaluated: (1) surgery vs. conservative care, and (2) different surgical techniques compared to one another. The methodological quality of the systematic reviews was evaluated using AMSTAR. We report (pooled) analyses from the individual reviews., Results: Thirteen systematic reviews on surgical interventions for low back disorders were included for disc herniation (n = 6), spondylolisthesis (n = 2), spinal stenosis (n = 4), and DDD (n = 4). Nine (69 %) were of high quality. Five reviews provided a meta-analysis of which two showed a significant difference. For the treatment of spinal stenosis, intervertebral process devices showed more favorable results compared to conservative treatment on the Zurich Claudication Questionnaire [mean difference (MD) 23.2 95 % CI 18.5-27.8]. For degenerative spondylolisthesis, fusion showed more favorable results compared to decompression for a mixed aggregation of clinical outcome measures (RR 1.40 95 % CI 1.04-1.89) and fusion rate favored instrumented fusion over non-instrumented fusion (RR 1.37 95 % CI 1.07-1.75)., Conclusions: For most of the comparisons, the included reviews were not significant and/or clinically relevant differences between interventions were identified. Although the quality of the reviews was quite acceptable, the quality of the included studies was poor. Future studies are likely to influence our assessment of these interventions.

Objectives To assess the use of prognostic patient factors and predictive tests in clinical decision making for spinal fusion in patients with chronic low back pain. Design and setting Nationwide survey among spine surgeons in the Netherlands. Participants Surgeon members of the Dutch Spine Society were questioned on their surgical treatment strategy for chronic low back pain. Primary and secondary outcome measures The surgeons' opinion on the use of prognostic patient factors and predictive tests for patient selection were addressed on Likert scales, and the degree of uniformity was assessed. In addition, the influence of surgeon-specific factors, such as clinical experience and training, on decision making was determined. Results The comments from 62 surgeons (70% response rate) were analysed. Forty-four surgeons (71%) had extensive clinical experience. There was a statistically significant lack of uniformity of opinion in seven of the 11 items on prognostic factors and eight of the 11 items on predictive tests, respectively. Imaging was valued much higher than predictive tests, psychological screening or patient preferences (all p<0.01). Apart from the use of discography and long multisegment fusions, differences in training or clinical experience did not appear to be of significant influence on treatment strategy. Conclusions The present survey showed a lack of consensus among spine surgeons on the appreciation and use of predictive tests. Prognostic patient factors were not consistently incorporated in their treatment strategy either. Clinical decision making for spinal fusion to treat chronic low back pain does not have a uniform evidence base in practice. Future research should focus on identifying subgroups of patients for whom spinal fusion is an effective treatment, as only a reliable prediction of surgical outcome, combined with the implementation of individual patient factors, may enable the instalment of consensus guidelines for surgical decision making in patients with chronic low back pain.

Study Design: A systematic review of randomized controlled trials., Objective: To determine which technique of anterior cervical interbody fusion (ACIF) gives the best outcome in patients with cervical degenerative disc disease., Summary of Background Data: The number of surgical techniques for decompression and ACIF as treatment for cervical degenerative disc disease has increased rapidly, but the rationale for the choice between different techniques remains unclear., Methods: From a comprehensive search, we selected randomized studies that compared anterior cervical decompression and ACIF techniques, in patients with chronic single- or double-level degenerative disc disease or disc herniation. Risk of bias was assessed using the criteria of the Cochrane back review group., Results: Thirty-three studies with 2267 patients were included. The major treatments were discectomy alone and addition of an ACIF procedure (graft, cement, cage, and plates). At best, there was very low-quality evidence of little or no difference in pain relief between the techniques. We found moderate quality evidence for few secondary outcomes. Odom's criteria were not different between iliac crest autograft and a metal cage (risk ratio [RR]: 1.11; 95% confidence interval [CI]: 0.99-1.24). Bone graft produced more fusion than discectomy (RR: 0.22; 95% CI: 0.17-0.48). Complication rates were not different between discectomy and iliac crest autograft (RR: 1.56; 95% CI: 0.71-3.43). Low-quality evidence was found that iliac crest autograft results in better fusion than a cage (RR: 1.87; 95% CI: 1.10-3.17); but more complications (RR: 0.33; 95% CI: 0.12-0.92)., Conclusion: When fusion of the motion segment is considered to be the working mechanism for pain relief and functional improvement, iliac crest autograft appears to be the golden standard. When ignoring fusion rates and looking at complication rates, a cage as a golden standard has a weak evidence base over iliac crest autograft, but not over discectomy.

Background: The number of surgical techniques for decompression and solid interbody fusion as treatment for cervical spondylosis has increased rapidly, but the rationale for the choice between different techniques remains unclear., Objectives: To determine which technique of anterior interbody fusion gives the best clinical and radiological outcomes in patients with single- or double-level degenerative disc disease of the cervical spine., Search Strategy: We searched CENTRAL (The Cochrane Library 2009, issue 1), MEDLINE (1966 to May 2009), EMBASE (1980 to May 2009), BIOSIS (2004 to May 2009), and references of selected articles., Selection Criteria: Randomised comparative studies that compared anterior cervical decompression and interbody fusion techniques for participants with chronic degenerative disc disease., Data Collection and Analysis: Two review authors independently assessed risk of bias using the Cochrane Back Review Group criteria. Data on demographics, intervention details and outcome measures were extracted onto a pre-tested data extraction form., Main Results: Thirty-three small studies ( 2267 patients) compared different fusion techniques. The major treatments were discectomy alone, addition of an interbody fusion procedure (autograft, allograft, cement, or cage), and addition of anterior plates. Eight studies had a low risk of bias. Few studies reported on pain, therefore, at best, there was very low quality evidence of little or no difference in pain relief between the different techniques. We found moderate quality evidence for these secondary outcomes: no statistically significant difference in Odom's criteria between iliac crest autograft and a metal cage (6 studies, RR 1.11 (95% CI 0.99 to1.24)); bone graft produced more effective fusion than discectomy alone (5 studies, RR 0.22 (95% CI 0.17 to 0.48)); no statistically significant difference in complication rates between discectomy alone and iliac crest autograft (7 studies, RR 1.56 (95% CI 0.71 to 3.43)); and low quality evidence that iliac crest autograft results in better fusion than a cage (5 studies, RR 1.87 (95% CI 1.10 to 3.17)); but more complications (7 studies, RR 0.33 (95% CI 0.12 to 0.92))., Authors' Conclusions: When the working mechanism for pain relief and functional improvement is fusion of the motion segment, there is low quality evidence that iliac crest autograft appears to be the better technique. When ignoring fusion rates and looking at complication rates, a cage has a weak evidence base over iliac crest autograft, but not over discectomy alone. Future research should compare additional instrumentation such as screws, plates, and cages against discectomy with or without autograft.

After decades of research, relatively little is known about the role of bone marrow stromal cells (BMSCs) for bone tissue engineering. Although homogeneous cell seeding is regarded optimal, cell survival in large constructs is unlikely, except for the very periphery. Also no minimal and optimal BMSC densities have been identified. An interesting development is the use of allogeneic BMSCs. These have not yet been compared directly to autologous BMSCs. Culture-expanded BMSCs of 10 Dutch milk goats were cryopreserved and peroperatively seeded on 7 mm cubic scaffolds of 65% porous biphasic calcium phosphate (BCP). A range of BMSC densities (per cm3 scaffold) were prepared of 8E2 (= 8 x 10(2)), 8E3, 8E4, 8E5, 8E6 (considered the standard), and 1.6E7. Each goat received a control without cells, the six densities, and an 8E6 allogeneic BMSCs construct intramuscularly. After 3, 5, and 7 weeks, fluorochrome markers were administrated. At 9 weeks, implants were retrieved. The BCP scaffolds appeared to be autoinductive as the controls (without BMSCs) showed some bone. Early bone formation (before 3 weeks) appeared only at the peripheral 2mm of the BMSC-seeded constructs; the later 5- and 9-week labels were found more centrally, suggesting bone migration to the center. There was a minimum of 8E4 and optimum of 8E6 BMSCs/cm3. Allogeneic cells yielded comparable new bone.

A disadvantage of traditional posterolateral spinal fusion models is that they are highly inefficient for screening multiple conditions. We developed a multiple-condition model that concentrates on the initial process of bone formation from the transverse process and not on a functional fusion. The effect of bone marrow stromal cells (BMSCs) in four different porous ceramic scaffolds was investigated in this setting. Polyacetal cassettes were designed to fit on the goat transverse process and house four different ceramic blocks, i.e: hydroxyapatite (HA) sintered at 1,150 degrees and 1,250 degrees; biphasic calcium phosphate (BCP) and tricalcium phosphate (TCP). Goat BMSCs (n=10) were cultured and per-operatively seeded autologeously on one of two cassettes implanted per animal. The cassettes were bilaterally mounted on the dorsum of decorticated L2-processes for 9 weeks. To asses the dynamics of bone formation, fluorochrome labels were administered and histomorphometry focused on the distribution of bone in the scaffolds. A clear difference in the extent of bone ingrowth was determined for the different scaffold types. An obvious effect of BMSC seeding was observed in three of four scaffold types, especially in scaffold regions adjacent to the overlying muscle. Generally, the BCP and TCP scaffolds showed better osteoconduction and an increased response to BMSCs administration. In conclusion the model provides a reliable and highly efficient method to study bone formation in cell-based tissue engineering. An effect of cell administration was obvious in three of the four scaffold materials.

Successful bone-tissue engineering (TE) has been reported for various strategies to combine cells with a porous scaffold. In particular, the period after seeding until implantation of the constructs may vary between hours and several weeks. Differences between these strategies can be reduced to (a) the presence of extracellular matrix, (b) the differentiation status of the cells, and (c) the presence of residual potentially immunogenic serum proteins. These parameters are investigated in two types of calcium phosphate scaffolds in a goat model of ectopic bone formation. Culture-expanded bone-marrow stromal cells from eight goats were seeded onto two types of hydroxyapatite granules: HA60/400 (60% porosity, 400-microm average pore size) and HA70/800. Scaffolds seeded with cells and control scaffolds were cultured for 6 days in medium containing autologous or semisynthetic serum, in the presence or absence of dexamethasone. Other scaffolds were seeded with cells just before implantation in medium with or without serum. All conditions were implanted autologously in the paraspinal muscles. After 12 weeks, bone had formed in 87% of all TE constructs, as demonstrated by histology. Histomorphometry indicated significantly more bone in the HA70/800 scaffolds. Furthermore, a significant advantage in bone formation was found when the constructs had been cultured for 6 days. In conclusion, both scaffold characteristics (porosity) and TE strategy (culturing of the constructs) were demonstrated to be important for bone TE., (Copyright 2004 Wiley Periodicals, Inc.)

Background: Little is known about the specific mechanisms that make autologous graft bone (AG) superior to the current alternatives. A potential mechanism is the active bone formation by the osteoprogenitor cells within the AG. However, whether these cells survive the transplantation is questionable, especially in nonvascularized, clinically sized grafts. In the present study, we investigated the role of viability in AG implanted ectopically and orthotopically in the goat., Methods: Eight goats were operated on twice. At the first operation, pieces of vital or devitalized autologous cortical bone were implanted in the paraspinal muscles. Eight weeks later, corticocancellous plugs were taken from the femoral condyles, morselized, and reimplanted as either vital or devitalized orthotopic grafts. The goats received fluorochrome labels at 5, 7, and 9 weeks after the first operation. At 12 weeks, the goats were killed, and the samples were examined histologically., Results: Ectopically, new bone had formed in both the vital and devitalized grafts. In the vital grafts, all three fluorochrome labels were present, indicating an early osteogenic mechanism. Within the devitalized grafts, only the 9-week label was observed. Histomorphometry indicated significantly more new bone in the vital grafts (10.3% vs. 1.7% in the devitalized grafts, P <0.01). Orthotopically, both vital and devitalized grafts showed new bone. Again, graft viability was advantageous in terms of new bone formation (14.5% vs. 9.3%, P <0.02)., Conclusion: The cells inside the autologous bone transplants most likely survived transplantation and were capable of initiating and sustaining new bone formation.