The Development of a Universally Accepted Sacral Fracture Classification: A Survey of AOSpine and AOTrauma Members.

Study Design Survey study. Objective To determine the global perspective on controversial aspects of sacral fracture classifications. Methods While developing the AOSpine Sacral Injury Classification System, a survey was sent to all members of AOSpine and AOTrauma. The survey asked four yes-or-no questions to help determine the best way to handle controversial aspects of sacral fractures in future classifications. Chi-square tests were initially used to compare surgeons\u27 answers to the four key questions of the survey, and then the data was modeled through multivariable logistic regression analysis. Results A total of 474 surgeons answered all questions in the survey. Overall 86.9% of respondents felt that the proposed hierarchical nature of injuries was appropriate, and 77.8% of respondents agreed that that the risk of neurologic injury is highest in a vertical fracture through the foramen. Almost 80% of respondents felt that the separation of injuries based on the integrity of L5-S1 facet was appropriate, and 83.8% of surgeons agreed that a nondisplaced sacral U fracture is a clinically relevant entity. Conclusion This study determines the global perspective on controversial areas in the injury patterns of sacral fractures and demonstrates that the development of a comprehensive and universally accepted sacral classification is possible

Sacral Fractures and Associated Injuries.

STUDY DESIGN: Literature review. OBJECTIVE: The aim of this review is to describe the injuries associated with sacral fractures and to analyze their impact on patient outcome. METHODS: A comprehensive narrative review of the literature was performed to identify the injuries associated with sacral fractures. RESULTS: Sacral fractures are uncommon injuries that result from high-energy trauma, and that, due to their rarity, are frequently underdiagnosed and mistreated. Only 5% of sacral fractures occur in isolation. Injuries most often associated with sacral fractures include neurologic injuries (present in up to 50% of sacral fractures), pelvic ring disruptions, hip and lumbar spine fractures, active pelvic/ abdominal bleeding and the presence of an open fracture or significant soft tissue injury. Diagnosis of pelvic ring fractures and fractures extending to the lumbar spine are key factors for the appropriate management of sacral fractures. Importantly, associated systemic (cranial, thoracic, and abdominopelvic) or musculoskeletal injuries should be promptly assessed and addressed. These associated injuries often dictate the management and eventual outcome of sacral fractures and, therefore, any treatment algorithm should take them into consideration. CONCLUSIONS: Sacral fractures are complex in nature and often associated with other often-missed injuries. This review summarizes the most relevant associated injuries in sacral fractures and discusses on their appropriate management

Tree regeneration and spatial patterning among midtolerant tree species following gap-based harvesting in a temperate hardwood forest

IntroductionField experiments of gap-based harvest systems in temperate northern hardwood forests have provided inconsistent support for the theory that such regeneration approaches can improve regeneration success among increasingly underrepresented tree species intermediate in shade tolerance. We established a field experiment in Wisconsin, USA testing the long-term response of tree regeneration to group selection harvesting that created small (50 m2–D:H 0.32), medium (200 m2—D:H 0.64) and large (380 m2—D:H 0.88) gaps.Materials and methodsLight levels were modeled to test the assumption of resource heterogeneity within and across these gap sizes. Spatial statistics were used to assess whether the point patterns of saplings of several midtolerant tree species (Betula alleghaniensis, Carya cordiformis, Fraxinus spp.) mapped in harvest gaps provided evidence for partitioning across resource gradients 9 years post-harvest. Finally, we measured occurrence and height of all saplings within the harvest gaps to test the effects of gap size and deer exclusion fencing on the density and total height of shade-tolerant and midtolerant tree regeneration.Results and discussionLight levels progressively increased with gap size, varied by position within gaps, and provided significant evidence of resource heterogeneity. The complex light gradients formed both within and across the three gap sizes may partially explain the statistically significant clustering of Fraxinus spp. saplings in gap centers and north and east into the forested edge of medium and large gaps, C. cordiformis on the west sides of forested transitions surrounding large gaps, and B. alleghaniensis in the centers of large gaps. Densities of tolerant and midtolerant saplings were similar in medium and large gaps after nine growing seasons, though tolerant saplings averaged two meters taller across all three gap sizes. Our results show that gap-based silvicultural systems can create resource gradients that are sufficient to regenerate mixtures of species with high to intermediate tolerance of shade. However, prescriptions beyond harvesting and deer exclusion fencing may be necessary for the recruitment of midtolerant species to canopy positions

Variation in global treatment for subaxial cervical spine isolated unilateral facet fractures.

PURPOSE To determine the variation in the global treatment practices for subaxial unilateral cervical spine facet fractures based on surgeon experience, practice setting, and surgical subspecialty. METHODS A survey was sent to 272 members of the AO Spine Subaxial Injury Classification System Validation Group worldwide. Questions surveyed surgeon preferences with regard to diagnostic work-up and treatment of fracture types F1-F3, according to the AO Spine Subaxial Cervical Spine Injury Classification System, with various associated neurologic injuries. RESULTS A total of 161 responses were received. Academic surgeons use the facet portion of the AO Spine classification system less frequently (61.6%) compared to hospital-employed and private practice surgeons (81.1% and 81.8%, respectively) (p = 0.029). The overall consensus was in favor of operative treatment for any facet fracture with radicular symptoms (N2) and for any fractures categorized as F2N2 and above. For F3N0 fractures, significantly less surgeons from Africa/Asia/Middle East (49%) and Europe (59.2%) chose operative treatment than from North/Latin/South America (74.1%) (p = 0.025). For F3N1 fractures, significantly less surgeons from Africa/Asia/Middle East (52%) and Europe (63.3%) recommended operative treatment than from North/Latin/South America (84.5%) (p = 0.001). More than 95% of surgeons included CT in their work-up of facet fractures, regardless of the type. No statistically significant differences were seen in the need for MRI to decide treatment. CONCLUSION Considerable agreement exists between surgeon preferences with regard to unilateral facet fracture management with few exceptions. F2N2 fracture subtypes and subtypes with radiculopathy (N2) appear to be the threshold for operative treatment

An international validation of the AO spine subaxial injury classification system.

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

Development of Online Technique for International Validation of the AO Spine Subaxial Injury Classification System.

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

Field Trial Results of an Improved Refractory Material for Slagging Gasifiers

Gasifiers are used commercially to react a carbon feedstock with water and oxygen under reducing conditions; producing chemicals used as feedstock for other processes, fuel for power plants, and/or steam used in other processes. A gasifier acts as a high temperature, high pressure reaction chamber, typically operating between 1250-1575°C, and with pressures between 300-1000 psi. Ash that originates from mineral impurities in the carbon feedstock becomes a by-product of gasification. In a slagging gasifier it melts, forming a liquid which flows down the gasifier sidewall; penetrating and wearing away the refractory liner by corrosive dissolution, abrasive wear, or by other processes such as spalling. The refractory liner must withstand the severe service environment, protecting the steel shell against corrosive gases, temperature, and material wear. Users have identified refractory service life as the most important limitation to sustained on-line availability of gasifiers, limiting gasifier acceptance and use by industry. The National Energy Technology Laboratory in Albany, OR, has developed and patented (US Patent # 6,815,386) a phosphate containing high chrome oxide refractory for use in slagging gasifiers. In cooperation with ANH Refractories Company, this refractory material has been commercially produced and is undergoing field tests in commercial gasifiers. An analysis of data from these field tests indicates that the phosphate containing refractory results in an improved service life over other refractory materials currently used as gasifier liners. Results from the post-mortem analysis of the field trial in relation to the failure mechanisms in a slagging gasifier will be presented

The Influence of Regional Differences on the Reliability of the AO Spine Sacral Injury Classification System.

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 (p2 = .0000) and A3 (p1 = .0280), B2 (p1 = .0015), C0 (p1 = .0085), and C2 (p1 =.0016, p2 =.0000) subtypes showed significant regional disparity in classification accuracy (p1 = Assessment 1, p2 = 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

Effect of surgical experience and spine subspecialty on the reliability of the AO Spine Upper Cervical Injury Classification System.

OBJECTIVE The objective of this paper was to determine the interobserver reliability and intraobserver reproducibility of the AO Spine Upper Cervical Injury Classification System based on surgeon experience ( 20 years) and surgical subspecialty (orthopedic spine surgery, neurosurgery, and "other" surgery). METHODS A total of 11,601 assessments of upper cervical spine injuries were evaluated based on the AO Spine Upper Cervical Injury Classification System. Reliability and reproducibility scores were obtained twice, with a 3-week time interval. Descriptive statistics were utilized to examine the percentage of accurately classified injuries, and Pearson's chi-square or Fisher's exact test was used to screen for potentially relevant differences between study participants. Kappa coefficients (κ) determined the interobserver reliability and intraobserver reproducibility. RESULTS The intraobserver reproducibility was substantial for surgeon experience level ( 20 years: 0.70) and surgical subspecialty (orthopedic spine: 0.71 vs neurosurgery: 0.69 vs other: 0.68). Furthermore, the interobserver reliability was substantial for all surgical experience groups on assessment 1 ( 20 years: 0.62), and only surgeons with > 20 years of experience did not have substantial reliability on assessment 2 ( 20 years: 0.59). Orthopedic spine surgeons and neurosurgeons had substantial intraobserver reproducibility on both assessment 1 (0.64 vs 0.63) and assessment 2 (0.62 vs 0.63), while other surgeons had moderate reliability on assessment 1 (0.43) and fair reliability on assessment 2 (0.36). CONCLUSIONS The international reliability and reproducibility scores for the AO Spine Upper Cervical Injury Classification System demonstrated substantial intraobserver reproducibility and interobserver reliability regardless of surgical experience and spine subspecialty. These results support the global application of this classification system

Establishing the Injury Severity of Subaxial Cervical Spine Trauma: Validating the Hierarchical Nature of the AO Spine Subaxial Cervical Spine Injury Classification System.

STUDY DESIGN Global cross-sectional survey. OBJECTIVE To validate the AO Spine Subaxial Cervical Spine Injury Classification by examining the perceived injury severity by surgeon across AO geographical regions and practice experience. SUMMARY OF BACKGROUND DATA Previous subaxial cervical spine injury classifications have been limited by subpar interobserver reliability and clinical applicability. In an attempt to create a universally validated scheme with prognostic value, AO Spine established a subaxial cervical spine injury classification involving four elements: (1) injury morphology, (2) facet injury involvement, (3) neurologic status, and (4) case-specific modifiers. METHODS A survey was sent to 272 AO Spine members across all geographic regions and with a variety of practice experience. Respondents graded the severity of each variable of the classification system on a scale from zero (low severity) to 100 (high severity). Primary outcome was to assess differences in perceived injury severity for each injury type over geographic regions and level of practice experience. RESULTS A total of 189 responses were received. Overall, the classification system exhibited a hierarchical progression in subtype injury severity scores. Only three subtypes showed a significant difference in injury severity score among geographic regions: F3 (floating lateral mass fracture, p:0.04), N3 (incomplete spinal cord injury, p:0.03), and M2 (critical disk herniation, p:0.04). When stratified by surgeon experience, pairwise comparison showed only 2 morphological subtypes, B1 (bony posterior tension band injury, p:0.02) and F2 (unstable facet fracture, p:0.03), and one neurologic subtype (N3, p:0.02) exhibited a significant difference in injury severity score. CONCLUSIONS The AO Spine Subaxial Cervical Spine Injury Classification System has shown to be reliable and suitable for proper patient management. The study shows this classification is substantially generalizable by geographic region and surgeon experience; and provides a consistent method of communication among physicians while covering the majority of subaxial cervical spine traumatic injuries.Level of Evidence: 4