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The CMS Submission Infrastructure (SI) is the main computing resource provisioning system for CMS workloads. A number of HTCondor pools are employed to manage this infrastructure, which aggregates geographically distributed resources from the WLCG and other providers. Historically, the model of authentication among the diverse components of this infrastructure has relied on the Grid Security Infrastructure (GSI), based on identities and X509 certificates. In contrast, commonly used modern authentication standards are based on capabilities and tokens. The WLCG has identified this trend and aims at a transparent replacement of GSI for all its workload management, data transfer and storage access operations, to be completed during the current LHC Run 3. As part of this effort, and within the context of CMS computing, the Submission Infrastructure group is in the process of phasing out the GSI part of its authentication layers, in favor of IDTokens and Scitokens. The use of tokens is already well integrated into the HTCondor Software Suite, which has allowed us to fully migrate the authentication between internal components of SI. Additionally, recent versions of the HTCondor-CE support tokens as well, enabling CMS resource requests to Grid sites employing this CE technology to be granted by means of token exchange. After a rollout campaign to sites, successfully completed by the third quarter of 2022, the totality of HTCondor CEs in use by CMS are already receiving Scitoken-based pilot jobs. On the ARC CE side, a parallel campaign was launched to foster the adoption of the REST interface at CMS sites (required to enable token-based job submission via HTCondor-G), which is nearing completion as well. In this contribution, the newly adopted authentication model will be described. We will then report on the migration status and final steps towards complete GSI phase out in the CMS SI.

The former CMS Run 2 High Level Trigger (HLT) farm is one of the largest contributors to CMS compute resources, providing about 25k job slots for offline computing. This CPU farm was initially employed as an opportunistic resource, exploited during inter-fill periods, in the LHC Run 2. Since then, it has become a nearly transparent extension of the CMS capacity at CERN, being located on-site at the LHC interaction point 5 (P5), where the CMS detector is installed. This resource has been configured to support the execution of critical CMS tasks, such as prompt detector data reconstruction. It can therefore be used in combination with the dedicated Tier 0 capacity at CERN, in order to process and absorb peaks in the stream of data coming from the CMS detector. The initial configuration for this resource, based on statically configured VMs, provided the required level of functionality. However, regular operations of this cluster revealed certain limitations compared to the resource provisioning and use model employed in the case of WLCG sites. A new configuration, based on a vacuum-like model, has been implemented for this resource in order to solve the detected shortcomings. This paper reports about this redeployment work on the permanent cloud for an enhanced support to CMS offline computing, comparing the former and new models’ respective functionalities, along with the commissioning effort for the new setup.

While the computing landscape supporting LHC experiments is currently dominated by x86 processors at WLCG sites, this configuration will evolve in the coming years. LHC collaborations will be increasingly employing HPC and Cloud facilities to process the vast amounts of data expected during the LHC Run 3 and the future HL-LHC phase. These facilities often feature diverse compute resources, including alternative CPU architectures like ARM and IBM Power, as well as a variety of GPU specifications. Using these heterogeneous resources efficiently is thus essential for the LHC collaborations reaching their future scientific goals. The Submission Infrastructure (SI) is a central element in CMS Computing, enabling resource acquisition and exploitation by CMS data processing, simulation and analysis tasks. The SI must therefore be adapted to ensure access and optimal utilization of this heterogeneous compute capacity. Some steps in this evolution have been already taken, as CMS is currently using opportunistically a small pool of GPU slots provided mainly at the CMS WLCG sites. Additionally, Power9 processors have been validated for CMS production at the Marconi-100 cluster at CINECA. This note will describe the updated capabilities of the SI to continue ensuring the efficient allocation and use of computing resources by CMS, despite their increasing diversity. The next steps towards a full integration and support of heterogeneous resources according to CMS needs will also be reported.

The computing resource needs of LHC experiments are expected to continue growing significantly during the Run 3 and into the HL-LHC era. The landscape of available resources will also evolve, as High Performance Computing (HPC) and Cloud resources will provide a comparable, or even dominant, fraction of the total compute capacity. The future years present a challenge for the experiments’ resource provisioning models, both in terms of scalability and increasing complexity. The CMS Submission Infrastructure (SI) provisions computing resources for CMS workflows. This infrastructure is built on a set of federated HTCondor pools, currently aggregating 400k CPU cores distributed worldwide and supporting the simultaneous execution of over 200k computing tasks. Incorporating HPC resources into CMS computing represents firstly an integration challenge, as HPC centers are much more diverse compared to Grid sites. Secondly, evolving the present SI, dimensioned to harness the current CMS computing capacity, to reach the resource scales required for the HLLHC phase, while maintaining global flexibility and efficiency, will represent an additional challenge for the SI. To preventively address future potential scalability limits, the SI team regularly runs tests to explore the maximum reach of our infrastructure. In this note, the integration of HPC resources into CMS offline computing is summarized, the potential concerns for the SI derived from the increased scale of operations are described, and the most recent results of scalability test on the CMS SI are reported.

The CMS experiment at CERN employs a distributed computing infrastructure to satisfy its data processing and simulation needs. The CMS Submission Infrastructure team manages a dynamic HTCondor pool, aggregating mainly Grid clusters worldwide, but also HPC, Cloud and opportunistic resources. This CMS Global Pool, which currently involves over 70 computing sites worldwide and peaks at 350k CPU cores, is employed to successfully manage the simultaneous execution of up to 150k tasks. While the present infrastructure is sufficient to harness the current computing power scales, CMS latest estimates predict a noticeable expansion in the amount of CPU that will be required in order to cope with the massive data increase of the High-Luminosity LHC (HL-LHC) era, planned to start in 2027. This contribution presents the latest results of the CMS Submission Infrastructure team in exploring and expanding the scalability reach of our Global Pool, in order to preventively detect and overcome any barriers in relation to the HL-LHC goals, while maintaining high effciency in our workload scheduling and resource utilization.

Efforts in distributed computing of the CMS experiment at the LHC at CERN are now focusing on the functionality required to fulfill the projected needs for the HL-LHC era. Cloud and HPC resources are expected to be dominant relative to resources provided by traditional Grid sites, being also much more diverse and heterogeneous. Handling their special capabilities or limitations and maintaining global flexibility and efficiency, while also operating at scales much higher than the current capacity, are the major challenges being addressed by the CMS Submission Infrastructure team. These proceedings discuss the risks to the stability and scalability of the CMS HTCondor infrastructure extrapolated to such a scenario, thought to be derived mostly from its growing complexity, with multiple Negotiators and schedulers flocking work to multiple federated pools. New mechanisms for enhanced customization and control over resource allocation and usage, mandatory in this future scenario, are also described.

Study Design: Retrospective review. Objective: To investigate the effect of age on the perioperative and radiographic complications associated with multilevel (>or=5) fusion of the cervicothoracic spine. Summary Of Background Data: Although the elderly comprise a substantial proportion of patients presenting with complex spinal pathology necessitating multilevel procedures across the cervical and cervicothoracic spine, the risk of perioperative and radiographic complications after these procedures is unknown. Methods: Between 2000 and 2007, 58 patients 65 years of age or older at a single institution underwent instrumented cervicothoracic spinal fusion of at least 5 levels. Fifty-eight patients under the age of 65 from the same time period served as a control group. A retrospective review of all hospital records, operative reports, radiographs, and clinic notes was conducted. Complications were classified as intraoperative, major and minor postoperative, and need for revision surgery. Flexion-extension radiographs were examined at discharge, 1.5, 6, 12 months, and then yearly, thereafter to evaluate fusion status and instrumentation-related complications. Results: Principal diagnoses included spondylostenosis, malignancy, vertebral fracture, and osteomyelitis. Both groups were similar in number of levels fused (elderly, 6.7 +/- 2.1; control, 6.3 +/- 1.7) and circumferential procedures (27 vs. 28), respectively. There were no significant differences in operative time, blood loss, or length of hospital stay. Rates of intraoperative (5.2% vs. 3.4%), major (20.7% vs. 17.2%) and minor postoperative complications (27.6% vs. 22.4%), and reoperation (8.6% vs. 8.6%) were similar between the 2 groups. Utilization of a combined anterior-posterior fusion was associated with increased perioperative complications in the elderly on univariate but not multivariate analyses. Radiographic evidence of fusion was also comparable between the 2 groups. Conclusion: Perioperative complication rates of multilevel (>or=5) cervicothoracic spinal fusion in the elderly are high but not significantly different from those of younger patients. The use of a circumferential fusion procedure may increase the risk of a perioperative complication in older patients. Fusion rates are similar between the 2 groups. [ABSTRACT FROM AUTHOR]

STUDY DESIGN: Retrospective review of the medical, radiographic, surgical, and postoperative records of patients who underwent resection of multilevel intradural extramedullary spinal cord tumors of the ventral cervical and cervicothoracic spine via a modified paramedian transpedicular approach at the University of California, San Francisco, between 2003 and 2005. OBJECTIVE: To assess the surgical, clinical, and radiographic outcomes of using the modified paramedian transpedicular approach to resect ventral intradural extramedullary spinal cord tumors of the ventral cervical and cervicothoracic spine. SUMMARY OF BACKGROUND DATA: A common theme of skull-base surgery for many years has been to remove the bone rather than retract neural elements. In this report, we demonstrate some possible advantages of taking a 'spine-base' approach for resecting intradural extramedullary spinal cord tumors of the ventral cervical and cervicothoracic spinal canal, and present our clinical experience. METHODS: All medical, surgical, and radiologic records were retrospectively reviewed. Clinical outcome was assessed for disability via the Neck Disability Index and for pain via the visual analog scale. RESULTS: Fourteen patients (4 males and 10 females, average age 39.6 years, range 20-62) with intradural extramedullary spinal cord tumors involving multiple levels of the anterior cervical and cervicothoracic spine were identified. All patients presented with pain and/or radiculomyelopathy attributed to a ventral intradural extramedullary spinal cord tumor of the cervical or cervicothoracic spine that was resected via the modified paramedian transpedicular approach with partial dorsal corpectomy and posterior spinal reconstruction. The average follow-up period was 14.6 months (range 5-30). Gross total resection was achieved in all cases, and no patient required additional surgery via an anterior approach for residual tumor. CONCLUSIONS: The modified paramedian transpedicular approach with partial dorsal corpectomy we describe here is a variation of traditional thoracic posterolateral transpedicular extracavitary approaches and offers direct access to lesions of the ventral cervicothoracic spinal canal. This approach avoids the morbidity of anterior transcervical, transoral, or transthoracic procedures, while providing a view of the entire ventral cervicothoracic canal, and can be performed safely and effectively in select patients. [ABSTRACT FROM AUTHOR]

Background: Treatment of spondylolisthesis can be difficult with regard to patients with high sacral slopes that may prohibit placement of interbody grafts for fusions across that segment. Here, we describe placement of a reverse Bohlman technique from an anterior approach to obtain fusion across a low-grade spondylolisthesis with a high sacral slope to obtain anterior fusion., Methods: A chart review was conducted on this single patient regarding his clinical course and outcome., Results: A 54-year-old male presented with low-back pain associated with bilateral leg pain dating back several years. Plain films demonstrated a Grade II isthmic spondylolisthesis at L5-S1 with spinopelvic measurements of 73° sacral slope, 82° lumbar lordosis, 12° pelvic tilt, and 94° pelvic incidence. Magnetic resonance imaging showed bilateral L5 pars defects with diffuse degenerative disease from L4 through S1 and significant ligamentous and facet hypertrophy. He underwent an L4-5 anterior lumbar interbody fusion and an L5-S1 reverse Bohlman placement of a transvertebral transsacral titanium mesh cage. This was supplemented with a posterior decompression and instrumentation from L4-ilium. He had resolution of his radiculopathy and has maintained a good clinical outcome at 3 years follow up., Conclusions: We present here a patient with low-grade spondylolisthesis and a steep sacral slope who underwent a successful reverse Bohlman approach with long-term follow up. This report highlights the potential utility of this method as a viable alternative for patients with low-grade spondylolisthesis., Level of Evidence: IV., Clinical Relevance: Technical description of surgical technique., Competing Interests: Disclosures and DOI: The authors have no commercial relationships or financial interests to disclose., (©International Society for the Advancement of Spine Surgery 2019.)

Study Design: Meta-analysis., Objective: The objective of this study was to determine whether adjunctive intrathecal morphine (ITM) reduces postoperative analgesic consumption following pediatric spine surgery., Summary of Background Data: Previous studies that have tested supplemental ITM to manage pain after pediatric spine surgery have been limited by small sample sizes., Methods: A comprehensive search of PubMed, Web of Science, Clinicaltrials.gov, and the Cochrane Central Register of Controlled Trials was performed for clinical trials and observational studies. Time to first analgesic demand, postoperative analgesic use, pain scores, and complication data were abstracted from each study. Mean difference (MD) and 95% confidence interval (CI) were used to compare continuous outcomes and odds ratios (OR) and 95% CI were used for dichotomous outcomes., Results: A total of 5 studies, including 3 randomized controlled trials and 2 retrospective chart reviews, containing 636 subjects, were incorporated into meta-analysis. Subjects that were administered ITM in addition to postoperative analgesics (ITM group) were compared with those receiving postoperative analgesics only (control group). In the ITM group, time to first analgesic demand was longer (MD, 8.79; 95% CI, 4.20-13.37; P<0.001), cumulative analgesic consumption was reduced at 24 hours (MD, -0.40; 95% CI, -0.56 to -0.24; P<0.001), and cumulative analgesic consumption was reduced at 48 hours (MD, -0.43; 95% CI, -0.59 to -0.27; P<0.001). Neither postoperative pain scores at 24 hours (P=0.16) nor 48 hours (P=0.18) were significantly different between ITM and control groups. Rates of respiratory depression, nausea, vomiting, and pruritus were not different between groups (all Ps>0.05)., Conclusions: Addition of ITM in pediatric spine surgery produced a potent analgesic effect in the immediate postoperative period. Patients administered ITM did not request opiates as early as control and consumed fewer opiates by the second postoperative day. Furthermore, use of ITM did not increase complications such as respiratory depression, nausea, vomiting, or pruritus.

Study Design: This is a cross-sectional study., Objective: To investigate spine surgeons' attitudes regarding preoperative anxiety measurement, management, and responsibility., Summary of Background Data: The vast majority of patients scheduled for spine surgery experience preoperative anxiety. However, there are currently no consensus guidelines for measure or management of preoperative anxiety in spinal operations., Materials and Methods: An anonymous questionnaire was sent online to spine surgeons of AO Spine North America to capture their views regarding preoperative anxiety., Results: Of 69 complete responses, most respondents were male (n=66, 95.7%), orthopedic surgeons (n=52, 75.4%), and practicing at an academic setting (n=39, 56.5%). Most spine surgeons practiced for at least 20 years (n=52, 75.4%), operated on 100-300 patients per year (n=48, 69.6%), and were attending physicians (n=61, 88.4%). Most did not measure preoperative anxiety (n=46, 66.7%) and would not use a rating scale to measure it (n=38, 55.1%). However, most would discuss it if mentioned by the patient (n=40, 58.0%). Other spine surgeons measured anxiety verbally (n=22, 31.9%) or with a rating scale or survey (n=6, 8.7%). Although preferences for preoperative anxiety management varied, most respondents used patient education (n=54, 78.3%) and permitting family members' presence (n=36, 52.2%) to reduce patient anxieties. Spine surgeons held themselves, anesthesiologists, and patients most responsible to manage preoperative anxiety., Conclusions: The majority of spine surgeons surveyed did not regularly measure preoperative anxiety, but would discuss its management if the subject was broached by the patient. Spine surgeons relied on a variety of methods to manage a patient's anxiety, but most preferred preoperative education and permitting the presence of family members. Responsibility for controlling preoperative anxiety was chiefly allocated to surgeons, anesthesiologists, and patients. Future avenues for research may include developing a preoperative anxiety measurement scale and management protocol specific to spine surgery., Level of Evidence: Level IV.

Study Design: This was a cross-sectional study., Objective: The objective of this study was to determine spine surgeons' preferences for the intraoperative and postoperative management of intraoperative durotomy (IDT) in decompression and spinal fusion surgeries., Summary of Background Data: Management guidelines for IDT remain elusive. Traditionally, management consists of intraoperative suturing and postoperative bed rest. However, preferences of North American spine surgeons may vary, particularly according to type of surgery., Materials and Methods: Spine surgeons of AO Spine North America (AOSNA) were surveyed online anonymously to determine which techniques they preferred to manage IDT in decompression and fusion. Differences in preferences according to surgery type were compared using the Fisher exact test. A series of linear regressions were conducted to identify demographic predictors of spine surgeons' preferences., Results: Of 217 respondents, most were male (95%), orthopedic surgeons (70%), practiced at an academic center (50%), were in practice 0-19 years (71%) and operated on 100-300 patients per year (70%). The majority of surgeons applied sutures (93%-96%) and sealant (82%-84%). Surgeons also used grafts (26%-27%), drains (18%), other techniques (4%-5%), blood patch (2%-3%), or no intraoperative management (1%-2%). Postoperatively, most surgeons recommended bed rest (74%-75%). Antibiotics (22%), immediate mobilization (18%-20%), reoperation (14%-16%), other techniques (6%), or no postoperative management (5%) were also preferred. Management preferences did not vary significantly between decompression and fusion surgeries (all P-values>0.05). Specialty, practice facility, years in practice, and patients per year were identified as independent predictors of IDT management preferences (P<0.05)., Conclusions: Although North American spine surgeons preferred to manage IDT with sutures augmented by sealant followed by bed rest after surgery, less common techniques were also preferred during the intraoperative and postoperative periods. Notably, intraoperative and postoperative IDT management preferences did not change in accordance to the type of surgery being conducted., Level of Evidence: Level V.

Background: Supplemental intrathecal morphine (ITM) represents an option to manage postoperative pain after spine surgery due to ease of administration and ability to confer effective short-term analgesia at low dosages. However, whether ITM increases risk of surgical site infections (SSI), cerebrospinal fluid (CSF) leak, and incidental dural tears (IDT) has not been investigated. Therefore, this study was performed to determine the rates of SSI, CSF leak, and IDT in patients that received ITM., Methods: Patients that underwent posterior instrumented fusion from January 2010 to 2016 that received ITM were compared to controls with respect to demographic, medical, surgical, and outcome data. Fisher's exact test was used to compare rates of SSI, CSF leak, and IDT between groups. Poisson regression was used to analyze complication rates after adjusting for the influence of covariates and potential confounders., Results: A total of 512 records were analyzed. ITM was administered to 78 patients prior to wound closure. The remaining 434 patients compromised the control group. IDT was significantly more common among patients receiving ITM (P=0.009). Differences in rates of CSF leak and SSI were not statistically significant (P=0.373 and P=0.564, respectively). After compensating for additional variables, Poisson regression revealed a significant increase in rates of IDT (P=0.007) according to ITM injection and advanced age (P=0.014). There was no significant difference in rates of CSF leak or SSI after accounting for the additional variables (P>0.05)., Conclusions: ITM for pain control in posterior instrumented spinal fusion surgery was linked to increased likelihood of IDT but not CSF leaks or SSI. Age was also noted to be a significant predictor of IDT. Spine surgeons should weigh potential risks against benefits when deciding whether to administer ITM for postoperative pain management following spine surgery., Competing Interests: Conflicts of Interest: The authors have no conflicts of interest to declare.

Background: The optimum pattern of pedicle screw (PS) fixation during long-segment thoracic fixation has not been determined., Objective: To evaluate rod stress and construct stability with minimal, alternating, skipped, and bilateral PS constructs in the iatrogenically destabilized thoracic spine., Methods: Eight cadaveric thoracic specimens (T3-T12) were initially tested intact to ±5 Nm using a custom 6 degree-of-freedom spine testing apparatus in flexion-extension (FE), lateral bending (LB), and axial rotation. Specimens were instrumented with T4-T10 bilateral PS, with Ponte osteotomies to introduce instability. Rods were bent to fit the PS and then spines were tested with the minimal, alternating, skipped, and bilateral fixation patterns. Range of motion (ROM) was calculated from T4-T10 and segmentally. In addition, strain gauges fixed to the spinal rods measured rod stress under FE and LB. Results were compared using ANOVA and post hoc Holm Sidak tests., Results: All fixation patterns provided significant reductions in ROM with respect to the intact spine. In all motion planes, minimal provided the least amount of rigidity, while bilateral provide the greatest; however, no statistically significant differences were detected in FE. In LB and axial rotation, skipped, alternating, and bilateral were all significantly more rigid than minimal (P < .01). Rod strains were greatest under LB and correlated with overall construct ROM, where bilateral had significantly lower strain than the other patterns (P < .05)., Conclusion: All constructs effectively decreased thoracic ROM. There was significant improvement in stabilization and decreased rod stress when more fixation points beyond the minimal construct were included., (Copyright © 2017 by the Congress of Neurological Surgeons)

Study Design: Retrospective review., Objective: To review the feasibility of a posterior-only approach for instrumented reconstruction in lumbar burst fractures., Background: Burst fractures of the lumbar spine have been treated through a variety of techniques, including anterior, posterior, or combined approaches. Here we review series of patients undergoing posterior-only transpedicular corpectomy with instrumented fusion for traumatic lumbar burst fracture., Methods: All patients treated at the Los Angeles County+University of Southern California (LAC+USC) Medical Center who had sustained traumatic lumbar burst fractures from February 2005 to February 2014 were reviewed., Results: A total of 178 traumatic lumbar burst fractures were identified of which 89 required operative intervention. Of those 89 operations, 7 patients underwent posterior-only approach for transpedicular corpectomy. Levels operated on were at L1 (4 patients), L2 (1 patient), and L4 (2 patients). The mean age was 35 years of age (range, 21-56 y), and mechanism of injury was either motor vehicle accident (5 patients) or fall (2 patients). Initial neurological examination was American Spinal Injury Association (ASIA) B in 3 patients, ASIA D in 3 patients, and 1 patient was neurologically intact. Mean thoracolumbar injury classification and severity score on presentation was 6.4 (range, 5-8), whereas the mean load sharing classification score was 7.4 (range, 7-9). Of patients who were not immediately lost to follow-up on hospital discharge, mean clinical follow-up was 45.3 months (range, 18.8-68.6 mo), whereas mean radiographic follow-up was 28.8 months (range, 1.3-63.6 mo). At the last known radiographic follow-up, no patient had gross hardware fracture, pseudoarthrosis, or adjacent segment disease. One patient with the longest radiographic follow-up of 63.6 months was noted to have some minimal subsidence of his cage with no other change in his other hardware., Conclusion: A posterior-only approach for transpedicular corpectomy and instrumented fusion is a viable treatment option for lumbar burst fracture which allows for reconstruction of the anterior column while avoiding many of the risks and complications associated with an anterior or combined approach.

Study Design: Retrospective cohort study., Objectives: Lateral interbody fixation is being increasingly used for the correction of segmental sagittal parameters. One factor that affects postoperative correction is the resistance afforded by posterior hypertrophic facet joints in the degenerative lumbar spine. In this article, we describe a novel preoperative motion segment classification system to predict postoperative correction of segmental sagittal alignment after lateral lumbar interbody fusion., Methods: Preoperative computed tomography scans were analyzed for segmental facet osseous anatomy for all patients undergoing lateral lumbar interbody fusion at 3 institutions. Each facet was assigned a facet grade (min = 0, max = 2), and the sum of the bilateral facet grades was the final motion segment grade (MSG; min = 0, max = 4). Preoperative and postoperative segmental lordosis was measured on standing lateral radiographs. Postoperative segmental lordosis was also conveyed as a percentage of the implanted graft lordosis (%GL). Simple linear regression was conducted to predict the postoperative segmental %GL according to MSG., Results: A total of 36 patients with 59 operated levels were identified. There were 19 levels with MSG 0, 14 levels with MSG 1, 13 levels with MSG 2, 8 levels with MSG 3, and 5 levels with MSG 4. Mean %GL was 115%, 90%, 77%, 43%, and 5% for MSG 0 to 4, respectively. MSG significantly predicted postoperative %GL ( P < .01). Each increase in MSG was associated with a 28% decrease in %GL., Conclusions: We propose a novel facet-based motion segment classification system that significantly predicted postoperative segmental lordosis after lateral lumbar interbody fusion., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Dr Acosta reports personal fees from NuVasive, outside the submitted work. Dr Hsieh reports personal fees from Depuy Synthes Spine, personal fees from Medtronic, and personal fees from Siemens, outside the submitted work. The remaining authors have no conflicts of interest to disclose.

Background Context: Watertight dural repair is crucial for both incidental durotomy and closure after intradural surgery., Purpose: The study aimed to describe a perfusion-based cadaveric simulation model with cerebrospinal fluid (CSF) reconstitution and to compare spine dural repair techniques., Study Design/setting: The study is set in a fresh tissue dissection laboratory., Sample Size: The sample includes eight fresh human cadavers., Outcome Measures: A watertight closure was achieved when pressurized saline up to 40 mm Hg did not cause further CSF leakage beyond the suture lines., Methods: Fresh human cadaveric specimens underwent cannulation of the intradural cervical spine for intrathecal reconstitution of the CSF system. The cervicothoracic dura was then exposed from C7-T12 via laminectomy. The entire dura was then opened in six cadavers (ALLSPINE) and closed with 6-0 Prolene (n=3) or 4-0 Nurolon (n=3), and pressurized with saline via a perfusion system to 60 mm Hg to check for leakage. In two cadavers (INCISION), six separate 2-cm incisions were made and closed with either 6-0 Prolene or 4-0 Nurolon, and then pressurized. A hydrogel sealant was then added and the closure was pressurized again to check for further leakage., Results: Spinal laminectomy with repair of intentional durotomy was successfully performed in eight cadavers. The operative microscope was used in all cases, and the model provided a realistic experience of spinal durotomy repair. For ALLSPINE cadavers (mean: 240 mm dura/cadaver repaired), the mean pressure threshold for CSF leakage was observed at 66.7 (±2.9) mm Hg in the 6-0 Prolene group and at 43.3 (±14.4) mm Hg in the 4-0 Nurolon group (p>.05). For INCISION cadavers, the mean pressure threshold for CSF leakage without hydrogel sealant was significantly higher in 6-0 Prolene group than in the 4-0 Nurolon group (6-0 Prolene: 80.0±4.5 mm Hg vs. 4-0 Nurolon: 32.5±2.7 mm Hg; p<.01). The mean pressure threshold for CSF leakage with the hydrogel sealants was not significantly different (6-0 Prolene: 100.0±0.0 mm Hg vs. 4-0 Nurolon: 70.0±33.1 mm Hg). The use of a hydrogel sealant significantly increased the pressure thresholds for possible CSF leakage in both the 6-0 Prolene group (p=.01) and the 4-0 Nurolon group (p<.01) when compared with mean pressures without the hydrogel sealant., Conclusions: We described the feasibility of using a novel cadaveric model for both the study and training of watertight dural closure techniques. 6-0 Prolene was observed to be superior to 4-0 Nurolon for watertight dural closure without a hydrogel sealant. The use of a hydrogel sealant significantly improved watertight dural closures for both 6-0 Prolene and 4-0 Nurolon groups in the cadaveric model., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background Context: Surgical treatment of symptomatic adjacent segment disease (ASD) typically involves extension of previous instrumentation to include the newly affected level(s). Disruption of the incision site can present challenges and increases the risk of complication. Lateral-based interbody fusion techniques may provide a viable surgical alternative that avoids these risks. This study is the first to analyze the biomechanical effect of adding a lateral-based construct to an existing fusion., Purpose: The study aimed to determine whether a minimally invasive lateral interbody device, with and without supplemental instrumentation, can effectively stabilize the rostral segment adjacent to a two-level fusion when compared with a traditional posterior revision approach., Study Design/setting: This is a cadaveric biomechanical study of lateral-based interbody strategies as add-on techniques to an existing fusion for the treatment of ASD., Methods: Twelve lumbosacral specimens were non-destructively loaded in flexion, extension, lateral bending, and torsion. Sequentially, the tested conditions were intact, two-level transforaminal lumbar interbody fusion (TLIF) (L3-L5), followed by lateral lumbar interbody fusion procedures at L2-L3 including interbody alone, a supplemental lateral plate, a supplemental spinous process plate, and then either cortical screw or pedicle screw fixation. A three-level TLIF was the final instrumented condition. In all conditions, three-dimensional kinematics were tracked and range of motion (ROM) was calculated for comparisons. Institutional funds (<$50,000) in support of this work were provided by Medtronic Spine., Results: The addition of a lateral interbody device superadjacent to a two-level fusion significantly reduced motion in flexion, extension, and lateral bending (p<.05). Supplementing with a lateral plate further reduced ROM during lateral bending and torsion, whereas a spinous process plate further reduced ROM during flexion and extension. The addition of posterior cortical screws provided the most stable lateral lumbar interbody fusion construct, demonstrating ROM comparable with a traditional three-level TLIF., Conclusions: The data presented suggest that a lateral-based interbody fusion supplemented with additional minimally invasive instrumentation may provide comparable stability with a traditional posterior revision approach without removal of the existing two-level rod in an ASD revision scenario., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: Bow Hunter's syndrome (BHS) is a rare condition characterized by vertebrobasilar insufficiency associated with rotational vertebral artery occlusion during head movement. Many existing reports describe surgical management, although no single technique has proven superior., Objective: To review all reported cases of BHS with focus on outcomes of individual techniques as well as to present a video report of a posterior decompression without fusion performed at the authors' institution., Methods: We searched PubMed for all relevant articles of BHS available in the English language. Pertinent studies were further characterized into surgical technique performed and associated outcomes., Results: We included 27 studies in our review, excluding the case presented, for a total of 65 cases of BHS. These cases discuss anterior versus posterior decompressions, the need for fusion, coil embolization techniques, the efficacy of intraoperative dynamic angiography, and success rate with symptom resolution being the primary endpoint. A total of 53 cases underwent decompression without fusion, with an overall success rate of 90.6% (n = 48/53). Similarly, eleven cases underwent decompression with fusion, with a success rate of 91% (n = 10/11). Two additional cases opted for coil embolization, one of which reported resolution of symptoms. Furthermore, we present a video case of a posterior decompression without fusion with resolution of symptoms., Conclusions: BHS remains a rare clinical condition with no clear superior method of treatment. Rates of symptom resolution are similar among cases undergoing decompression with or without fusion. Coil embolization has been reported with limited success in 2 cases., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Study Design: Meta-analysis of randomized controlled trials (RCTs)., Objective: The aim of this study was to evaluate the effectiveness of intrathecal morphine (ITM) in reducing postoperative pain and opioid analgesic consumption following spine surgery., Summary of Background Data: The use of ITM following adult spine surgery is of particular interest because of the ease of access to the thecal sac and the potential to provide adequate analgesia at low doses. However, previous studies of ITM have been limited by small sample sizes and conflicting results., Methods: A comprehensive search of PubMed, Web of Science, Clinicaltrials.gov, and the Cochrane Central Register of Controlled Trials for prospective RCTs was performed by two independent reviewers. Postoperative opioid consumption, pain scores, and complications were documented from the identified studies. Standard mean differences (SMDs) were applied to continuous outcomes and odds ratios were determined for dichotomous outcomes., Results: Eight RCTs involving 393 subjects met inclusion criteria and were included in this meta-analysis. Patients receiving ITM (ITM group) as an adjunct to postoperative opioid analgesic were compared to patients receiving postoperative opioids only (control group). Postoperative morphine equivalent consumption was significantly lower during the first 24 hours postoperative in the ITM group (P < 0.001). Pain scores were similarly lower in the first 24 hours following spine surgery in those who received ITM (P < 0.001). In patients administered ITM, a greater percentage experienced pruritus (P < 0.001). Respiratory depression was solely encountered in the ITM group (P = 0.25). There were no significant differences between the ITM and control groups in terms of sedation (P = 0.18), nausea (P = 0.67), vomiting (P = 0.62), or length of stay (P = 0.13)., Conclusion: In patients undergoing spine surgery, use of ITM significantly reduced opioid analgesic consumption and Visual Analogue Schores pain scores compared to controls within the first 24 hours postoperatively. High-quality, follow-up RCTs with large sample sizes are recommended to determine the potential of supplementary ITM in spine surgery and complete the side effects profile., Level of Evidence: 1.

Study Design: Retrospective analysis of a nationwide private insurance database. Chi-square analysis and linear regression models were utilized for outcome measures., Purpose: The purpose of this study was to investigate any relationship between lumbar degenerative disc disease, diabetes, obesity and smoking tobacco., Overview of Literature: Diabetes, obesity, and smoking tobacco are comorbid conditions known to individually have effect on degenerative disc disease. Most studies have only been on a small populous scale. No study has yet to investigate the combination of these conditions within a large patient cohort nor have they reviewed the combination of these conditions on degenerative disc disease., Methods: A retrospective analysis of insurance billing codes within the nationwide Humana insurance database was performed, using PearlDiver software (PearlDiver, Inc., Fort Wayne, IN, USA), to identify trends among patients diagnosed with lumbar disc degenerative disease with and without the associated comorbidities of obesity, diabetes, and/or smoking tobacco. Patients billed for a comorbidity diagnosis on the same patient record as the lumbar disc degenerative disease diagnosis were compared over time to patients billed for lumbar disc degenerative disease without a comorbidity. There were no sources of funding for this manuscript and no conflicts of interest., Results: The total number and prevalence of patients (per 10,000) within the database diagnosed with lumbar disc degenerative disease increased by 241.4% and 130.3%, respectively. The subsets of patients within this population who were concurrently diagnosed with either obesity, diabetes, tobacco use, or a combination thereof, was significantly higher than patients diagnosed with lumbar disc degenerative disease alone ( p <0.05 for all). The number of patients diagnosed with lumbar disc degenerative disease and smoking rose significantly more than patients diagnosed with lumbar disc degenerative disease and either diabetes or obesity ( p <0.05). The number of patients diagnosed with lumbar disc degenerative disease, smoking and obesity rose significantly more than the number of patients diagnosed with lumbar disc degenerative disease and any other comorbidity alone or combination of comorbidities ( p <0.05)., Conclusions: Diabetes, obesity and cigarette smoking each are significantly associated with an increased diagnosis of lumbar degenerative disc disease. The combination of smoking and obesity had a synergistic effect on increased rates of lumbar degenerative disc disease. Patient education and preventative care is a vital goal in prevention of degenerative disc disease within the general population., Competing Interests: Conflict of Interest: No potential conflict of interest relevant to this article was reported.

There has been a conscious effort to address osteoporosis in the aging population. As bisphosphonate and intermittent parathyroid hormone (PTH) therapy become more widely prescribed to treat osteoporosis, it is important to understand their effects on other physiologic processes, particularly the impact on spinal fusion. Despite early animal model studies and more recent clinical studies, the impact of these medications on spinal fusion is not fully understood. Previous animal studies suggest that bisphosphonate therapy resulted in inhibition of fusion mass with impeded maturity and an unknown effect on biomechanical strength. Prior animal studies demonstrate an improved fusion rate and fusion mass microstructure with the use of intermittent PTH. The purpose of this study was to determine if bisphosphonates and intermittent PTH treatment have impact on human spinal fusion. A systematic review of the literature published between 1980 and 2015 was conducted using major electronic databases. Studies reporting outcomes of human subjects undergoing 1, 2, or 3-level spinal fusion while receiving bisphosphonates and/or intermittent PTH treatment were included. The results of relevant human studies were analyzed for consensus on the effects of these medications in regards to spinal fusion. There were nine human studies evaluating the impact of these medications on spinal fusion. Improved fusion rates were noted in patients receiving bisphosphonates compared to control groups, and greater fusion rates in patients receiving PTH compared to control groups. Prior studies involving animal models found an improved fusion rate and fusion mass microstructure with the use of intermittent PTH. No significant complications were demonstrated in any study included in the analysis. Bisphosphonate use in humans may not be a deterrent to spinal fusion. Intermittent parathyroid use has shown early promise to increase fusion mass in both animal and human studies but further studies are needed to support routine use., Competing Interests: Conflict of Interest: No potential conflict of interest relevant to this article was reported.

Animal and human studies demonstrate the anabolic properties of low-magnitude mechanical stimulation (LMMS) in its ability to improve bone formation by enhancing the proliferation of mesenchymal stem cells and their subsequent commitment down an osteoblastic lineage. Response to mechanical strains as low as 10μɛ have been seen, illustrating the sensitivity of mechanosensory cells to mechanotransduction pathways. Applications to the spine include treatment of osteoporosis in preparation for instrumented fusion, fracture reduction in spinal cord injury patients to slow bone mineral density loss, and bone tissue engineering and enhancement of bone-implant osseointegration for pseudarthrosis and hardware failure. This review provides an overview of the fundamentals of LMMS, highlights the cellular basis and biomechanics of how mechanical strain is translated into bone formation, and then discusses current and potential applications of these concepts to spinal disorders. Mechanical signals represent a key regulatory mechanism in the maintenance and formation of bone. Developing practical clinical applications of these mechanotransduction pathways continues to be an important area of investigation in its relation to spinal pathology., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The past several years have demonstrated an increased recognition of operative videos as an important adjunct for resident education. Currently lacking, however, are effective methods to record video for the purposes of illustrating the techniques of minimally invasive (MIS) and complex spine surgery. We describe here our experiences developing and using a shoulder-mounted camera system for recording surgical video. Our requirements for an effective camera system included wireless portability to allow for movement around the operating room, camera mount location for comfort and loupes/headlight usage, battery life for long operative days, and sterile control of on/off recording. With this in mind, we created a shoulder-mounted camera system utilizing a GoPro™ HERO3+, its Smart Remote (GoPro, Inc., San Mateo, California), a high-capacity external battery pack, and a commercially available shoulder-mount harness. This shoulder-mounted system was more comfortable to wear for long periods of time in comparison to existing head-mounted and loupe-mounted systems. Without requiring any wired connections, the surgeon was free to move around the room as needed. Over the past several years, we have recorded numerous MIS and complex spine surgeries for the purposes of surgical video creation for resident education. Surgical videos serve as a platform to distribute important operative nuances in rich multimedia. Effective and practical camera system setups are needed to encourage the continued creation of videos to illustrate the surgical maneuvers in minimally invasive and complex spinal surgery. We describe here a novel portable shoulder-mounted camera system setup specifically designed to be worn and used for long periods of time in the operating room.

Proximal junctional kyphosis is an increasingly recognized complication following long-segment posterior spinal fusion for adult spinal deformity. The authors describe a novel technique for interspinous ligament reinforcement at the proximal adjacent levels using a cadaveric semitendinosus tendon graft secured with an Ethibond No. 2 double filament (Ethicon, Somerville, New Jersey) via the Krackow suture weave. A retrospective review identified 4 patients who had received this graft. No proximal junctional kyphosis was seen at a mean short-term follow-up of 5.5 months. Interspinous ligament reinforcement at the proximal adjacent level with a cadaveric semitendinosus tendon graft is a feasible strategy for preventing proximal junctional kyphosis. [Orthopedics. 2017; 40(1):e206-e210.]., (Copyright 2016, SLACK Incorporated.)

Study Design Biomechanical cadaveric study. Objective Clinical studies indicate that using less-rigid fixation techniques in place of the standard all-pedicle screw construct when correcting for scoliosis may reduce the incidence of proximal junctional kyphosis and improve patient outcomes. The purpose of this study is to investigate whether there is a biomechanical advantage to using supralaminar hooks in place of pedicle screws at the upper-instrumented vertebrae in a multilevel thoracic construct. Methods T7-T12 spines were biomechanically tested: (1) intact; (2) following a two-level pedicles screw fusion from T9 to T11; and after proximal extension of the fusion to T8-T9 with (3) bilateral supra-laminar hooks, (4) a unilateral hook + unilateral screw hybrid, or (5) bilateral pedicle screws. Specimens were nondestructively loaded while three-dimensional kinematics and intradiscal pressure at the supra-adjacent level were recorded. Results Supra-adjacent hypermobility was reduced when bilateral hooks were used in place of pedicle screws at the upper-instrumented level, with statistically significant differences in lateral bending and torsion (p < 0.05 and p < 0.001, respectively). Disk pressures in the supra-adjacent segment were not statistically different among top-off techniques. Conclusions The use of supralaminar hooks at the top of a multilevel posterior fusion construct reduces the stress at the proximal uninstrumented motion segment. Although further data is needed to provide a definitive link to the clinical occurrence of PJK, this in vitro study demonstrates the potential benefit of "easing" the transition between the stiff instrumented spine and the flexible native spine and is the first to demonstrate these results with laminar hooks.

Introduction: Although the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) for spinal fusion has been fairly studied in the general population, relatively little research has been conducted on its use in the elderly patient demographic despite this population's growth. The authors sought to examine the clinical efficacy, complication rate, and cost-effectiveness of rhBMP-2 use in elderly patients undergoing spinal fusion surgery., Evidence Acquisition: We conducted a systematic review of the published literature for elderly patients that underwent spinal fusion surgery with the use of rhBMP-2. A systematic search was performed utilizing the PUBMED and MEDLINE databases in order to identify all papers dealing with recombinant human Bone Morphogenic Protein-2 use in patients over the age of 60 years., Evidence Synthesis: Twenty-five papers were identified that met our inclusion criteria. While successful fusion, improvement in pain, and improved quality of life were encountered in elderly patients who were treated with fusions surgery along with rhBMP-2, there were several complications that were encountered including seroma formation, pleural effusions, and bone non-union., Conclusions: The literature demonstrated that BMP serves as a potent osteoinductive agent in the elderly with similar efficacy to bone autograft. Although use of BMP showed mixed results and had higher initial costs, when taken into account with complication correction and costs, BMP usage appears to be more economically beneficial overall. Future studies are needed to clarify the clinical significance of the complications encountered in elderly patients treated with rhBMP-2. Future research can assist in developing recommendations which can minimize these risks in the elderly patient demographic.

OBJECTIVE The objective of this study was to determine factors associated with admission to the hospital through the emergency room (ER) for patients with a primary diagnosis of low-back pain (LBP). The authors further evaluated the impact of ER admission and patient characteristics on mortality, discharge disposition, and hospital length of stay. METHODS The authors conducted a retrospective analysis of patients with LBP discharged from hospitals according to the Nationwide Inpatient Sample (NIS) between 1998 and 2007. Univariate comparisons of patient characteristics according to the type of admission (ER versus non-ER) were conducted. Multivariate analysis evaluated factors associated with an ER admission, risk of mortality, and nonroutine discharge. RESULTS According to the NIS, approximately 183,151 patients with a primary diagnosis of LBP were discharged from US hospitals between 1998 and 2007. During this period, an average of 65% of these patients were admitted through the ER, with a significant increase from 1998 (54%) to 2005 (71%). Multivariate analysis revealed that uninsured patients (OR 2.1, 95% CI 1.7-2.6, p < 0.0001) and African American patients (OR 1.5, 95% CI 1.2-1.7, p < 0.0001) were significantly more likely to be admitted through the ER than private insurance patients or Caucasian patients, respectively. Additionally, a moderate but statistically significant increase in the likelihood of ER admission was noted for patients with more preexisting comorbidities (OR 1.1, 95% CI 1.0-1.2, p < 0.001). An 11% incremental increase in the odds of admission through the ER was observed with each year increment (OR 1.1, 95% CI 1.0-1.2, p < 0.001). Highest income patients ($45,000+) were more likely to be admitted through the ER (OR 1.3, 95% CI 1.1-1.6, p = 0.007) than the lowest income cohort. While ER admission did not impact the risk of mortality (OR 0.95, 95% CI 0.60-1.51, p = 0.84), it increased the odds of a nonroutine discharge (OR 1.39, 95% CI 1.26-1.53, p < 0.0001). CONCLUSIONS A significant majority of patients discharged from hospitals in the US from 1998 to 2007 with a primary diagnosis of LBP were admitted through the ER, with more patients being admitted via this route each year. These patients were less likely to be discharged directly home compared with patients with LBP who were not admitted through the ER. Uninsured and African American patients with LBP were more likely to be admitted through the ER than their counterparts, as were patients with more preexisting health problems. Interestingly, patients with LBP at the highest income levels were more likely to be admitted through hospital ERs. The findings suggest that socioeconomic factors may play a role in the utilization of ER resources by patients with LBP, which in turn appears to impact at least the short-term outcome of these patients.

Commentary on: Wheeler DL, Fredericks DC, Dryer RF, Bae HW. Allogeneic mesenchymal precursor cells (MPCs) combined with an osteoconductive scaffold to promote lumbar interbody spine fusion in an ovine model. Spine J 2016:16:389-99 (in this issue)., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Object: The objective of this study was to compare the incidence of degeneration and need for subsequent fusion surgery between patients who were treated nonsurgically and patients treated with fusion after a diagnosis of thoracic-or lumbar-level fracture without degenerative disease., Methods: The authors performed a retrospective study of Orthopedic United Healthcare patients diagnosed with thoracic or lumbar fracture. Patients were filtered into thoracic and lumbar fracture groups using diagnostic codes and then assigned to one of 2 treatment subgroups (fusion surgery or no surgery) on the basis of procedural codes. Disc degeneration and follow-up surgery were recorded. Chi-square statistical analysis was used., Results: Of 3699 patients diagnosed with a thoracic fracture, 117 (3.2%) underwent thoracic fusion and 3215 (86.9%) were treated nonsurgically. Within 3 years, 147 (4.6%) patients from the nonsurgical subgroup and fewer than 11 (0.9%-8.5%) from the fusion subgroup were diagnosed with thoracic disc degeneration. From the nonsurgical subgroup, 11 (0.3%) patients underwent a thoracic surgery related to disc degeneration compared with zero from the fusion group (p > 0.05). Of 5016 patients diagnosed with lumbar fracture, 150 (3.0%) underwent fusion and 4371 (87.1%) had no surgery. Within 3 years, 503 patients (11.5%) from the nonsurgical subgroup and 35 (23.3%) from the fusion subgroup were diagnosed with lumbar disc degeneration (p < 0.05). From the nonsurgical subgroup, 42 (1.0%) went on to have surgery related to disc degeneration, compared with fewer than 11 (0.7%-6.7%) from the fusion subgroup (values not precise due to privacy limitations)., Conclusions: Fusion surgery for thoracic fracture does not appear to increase the likelihood of undergoing future surgery. In the lumbar region, initial fusion surgery appears to increase the incidence of disc degeneration and could potentially necessitate future surgeries.

The Dynesys dynamic stabilization system is an alternative to rigid instrumentation and fusion for the treatment of lumbar degenerative disease. Although many outcomes studies have shown good results, currently lacking is a comprehensive report on complications associated with this system, especially in terms of how it compares with reported complication rates of fusion. For the present study, the authors reviewed the literature to find all studies involving the Dynesys dynamic stabilization system that reported complications or adverse events. Twenty-one studies were included for a total of 1166 patients with a mean age of 55.5 years (range 39-71 years) and a mean follow-up period of 33.7 months (range 12.0-81.6 months). Analysis of these studies demonstrated a surgical-site infection rate of 4.3%, pedicle screw loosening rate of 11.7%, pedicle screw fracture rate of 1.6%, and adjacent-segment disease (ASD) rate of 7.0%. Of studies reporting revision surgeries, 11.3% of patients underwent a reoperation. Of patients who developed ASD, 40.6% underwent a reoperation for treatment. The Dynesys dynamic stabilization system appears to have a fairly similar complication-rate profile compared with published literature on lumbar fusion, and is associated with a slightly lower incidence of ASD.

We evaluated the Nationwide Inpatient Sample (NIS) database for increased hospital acquired condition (HAC) rate as a function of weekend admission in patients receiving thoracolumbar fusions. In 2008, the Centers for Medicare and Medicaid Services (CMS) compiled a list of HAC for a new payment policy for preventable adverse events without reimbursement of resulting hospital costs. In this, the thoracolumbar patients represented a population with significant increased rates of HAC and, to our knowledge, no prior studies have evaluated the effect of weekend admission on HAC rate. We collated data for patients who underwent thoracolumbar fusions from the 2002-2010 NIS database. Using CMS definitions, HAC were abstracted using the Ninth Edition of International Classification of Diseases Clinical Modification (ICD-9CM). Multivariate analysis assessed the impact of a weekend admission on HAC occurrence and prolonged length of stay (LOS) adjusting for patient, admission severity, and hospital covariates. There were 1,842,231 total admissions between 2002 and 2010 associated with thoracolumbar procedures. HAC occurred at a frequency of 5.2% overall. Surgical site infections (n=10,656) and falls/trauma (n=83,999) were the most common. After adjusting for disease severity and urgency of admission, patients admitted on the weekend were more than two times more likely to incur a HAC compared to those admitted on weekdays (odds ratio 2.41; 95% confidence interval 2.19-2.65; p<0.05). HAC occurrence and weekend admission were also associated with prolonged LOS (p<0.05). We found that weekend admission is associated with increased HAC rate. Though our conclusions must be tempered by limitations of the coded national database, further study is warranted to confirm this disparity and evaluate potential for improvement., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background: Hospital-acquired conditions (HACs) are defined by the Centers for Medicaid and Medicare Services (CMS) as preventable adverse events that do not qualify for reimbursement of resulting hospital costs. HACs have been employed as a metric for quality of patient care. Patients undergoing cervical spine fusions are at risk for occurrence of HACs because of limited mobility and potential extended hospital length of stay (LOS). Previous studies have not evaluated the contribution of weekend admission on the rate of HACs in this patient population. We abstracted data from the Nationwide Inpatient Sample to evaluate rate of HACs as a function of weekend admission among patients admitted for cervical fusions., Methods: Patients undergoing anterior and posterior cervical fusions were identified from the 2002-2010 Nationwide Inpatient Sample database. HACs as defined by the CMS were collected via International Classification of Diseases, Ninth Revision, Clinical Modification codes. Multivariate analysis, including adjustment for demographics, disease severity, admission acuity, and admission source, was used to evaluate the effect of weekend admission on HAC occurrence, prolonged LOS, and higher inpatient costs., Results: During the period 2002-2010, 1,404,181 admissions for cervical fusion were identified. HACs occurred at a frequency of 4.6%. After multivariate adjustment for demographics, disease severity, and urgency of admission, weekend admissions were associated with a 56% increased risk of HAC occurrence compared with weekday admissions (relative risk = 1.56, 95% confidence interval = 1.51, 1.62, P < 0.01). HAC occurrence was independently associated with prolonged LOS and higher inpatient costs (P < 0.05)., Conclusions: Patients undergoing cervical fusions who are admitted on weekends have an increased rate of HACs. HACs were associated with increases in LOS and hospital costs. Further study is warranted to evaluate disparities and potential improvement among weekend admissions., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Three column osteotomies (3CO) of the lumbar spine are powerful corrective procedures used in the treatment of kyphoscoliosis. Their efficacy comes at the cost of high reported complication rates, notably significant estimated blood loss (EBL). Previously reported techniques to reduce EBL have had modest efficacy. Here we describe a potential technique to decrease EBL during pedicle subtraction osteotomy (PSO) of the lumbar spine by means of pre-operative vertebral body embolization - a technique traditionally used to reduce blood loss prior to spinal column tumor resection. We present a 62-year-old man with iatrogenic kyphoscoliosis who underwent staged deformity correction. Stage 1 involved thoracolumbar instrumentation followed by transarterial embolization of the L4 vertebral body through bilateral segmental arteries. A combination of polyvinyl alcohol particles and Gelfoam (Pfizer, New York, NY, USA) were used. Following embolization there was decreased angiographic blood flow to the small vessels of the L4 vertebral body, while the segmental arteries remained patent. Stage 2 consisted of an L4 PSO and fusion. The EBL during the PSO procedure was 1L, which compared favorably to that during previous PSO at this institution as well as to quantities reported in previous literature. There have been no short term (5 month follow-up) complications attributable to the vertebral body embolization or surgical procedure. Although further investigation into this technique is required to better characterize its safety and efficacy in reducing EBL during 3CO, we believe this patient illustrates the potential utility of pre-operative vertebral embolization in the setting of non-oncologic deformity correction surgery., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Lateral interbody fusion techniques are heavily reliant on fluoroscopy for retractor docking and graft placement, which expose both the patient and surgeon to high doses of radiation. Use of image-guided technologies with CT-based images, however, can eliminate this radiation exposure for the surgeon. We describe the surgical technique of performing lateral lumbar interbody fusion using CT navigation., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Background: Lateral interbody fusion techniques have been linked with considerable postoperative morbidity, often the outcome of direct psoas trauma. The most common neurological postoperative complications are transient motor weakness/palsy and sensory dysesthesia, which can be permanent. It appears that these neural complications are a result of passing through the psoas muscle where the potential for nerve injury is significant. The supra-psoas shallow docking method may be a safer alternative and may help minimize morbidities by eliminating or reducing direct psoas injury., Objective: To describe the operative technique of performing lateral interbody fusion using supra-psoas retractor docking., Methods: The authors describe the surgical technique including side selection, positioning, and patient outcomes., Results: Fifteen patients were treated with the supra-psoas shallow docking method. Specifically, no patient reported weakness, numbness, and/or pain on the side that underwent the surgery. In these cases, performing lateral transpsoas interbody fusion using supra-psoas shallow docking appeared to minimize the most common neurological postoperative complications of the surgery, motor weakness/palsy and sensory dysesthesia, which may be a result of dilation of the psoas muscle., Conclusion: The shallow docking technique may decrease postoperative morbidities by docking on top of psoas muscle instead of passing through it. An important potential benefit of this approach is direct visualization of the lumbosacral plexus, which may potentially minimize the postoperative neurological morbidity often encountered in patients after this surgery.

This paper is a narrative review of normal cervical alignment, methods for quantifying alignment, and how alignment is associated with cervical deformity, myelopathy, and adjacent-segment disease (ASD), with discussions of health-related quality of life (HRQOL). Popular methods currently used to quantify cervical alignment are discussed including cervical lordosis, sagittal vertical axis, and horizontal gaze with the chin-brow to vertical angle. Cervical deformity is examined in detail as deformities localized to the cervical spine affect, and are affected by, other parameters of the spine in preserving global sagittal alignment. An evolving trend is defining cervical sagittal alignment. Evidence from a few recent studies suggests correlations between radiographic parameters in the cervical spine and HRQOL. Analysis of the cervical regional alignment with respect to overall spinal pelvic alignment is critical. The article details mechanisms by which cervical kyphotic deformity potentially leads to ASD and discusses previous studies that suggest how postoperative sagittal malalignment may promote ASD. Further clinical studies are needed to explore the relationship of cervical malalignment and the development of ASD. Sagittal alignment of the cervical spine may play a substantial role in the development of cervical myelopathy as cervical deformity can lead to spinal cord compression and cord tension. Surgical correction of cervical myelopathy should always take into consideration cervical sagittal alignment, as decompression alone may not decrease cord tension induced by kyphosis. Awareness of the development of postlaminectomy kyphosis is critical as it relates to cervical myelopathy. The future direction of cervical deformity correction should include a comprehensive approach in assessing global cervicalpelvic relationships. Just as understanding pelvic incidence as it relates to lumbar lordosis was crucial in building our knowledge of thoracolumbar deformities, T-1 incidence and cervical sagittal balance can further our understanding of cervical deformities. Other important parameters that account for the cervical-pelvic relationship are surveyed in detail, and it is recognized that all such parameters need to be validated in studies that correlate HRQOL outcomes following cervical deformity correction.

Background Context: Scoliosis is a significant cause of disability and health-care resource utilization in the United States., Purpose: Our aim was to evaluate potential disparities in the selection of treatments and outcomes for idiopathic scoliosis patients on a national level. To date, only one study has examined inpatient complications, discharge disposition, and mortality with respect to scoliosis treatment on a national scale., Study Design/setting: Retrospective review of cases having a primary diagnosis of idiopathic scoliosis using the nationwide inpatient sample (NIS) administrative data from 1998 to 2007., Patient Sample: The NIS data were queried to identify patients with a primary diagnosis of idiopathic scoliosis (International Classification of Diseases, Ninth Revision [ICD-9] diagnosis code: 737.30) admitted routinely. Surgically treated patients were identified as those patients who underwent a spinal fusion (ICD-9-Clinical Modification code: 81.08) as a principal procedure., Outcome Measures: Rates of surgical versus nonsurgical treatments were measured as were inhospital complications and mortality rates., Methods: No external funding was received for this work. Univariate and multivariate analyses evaluated race, sex, socioeconomic factors, and hospital characteristics as predictors of surgical versus nonsurgical treatments, as well as inhospital complications and mortality rates., Results: The study analyzed 9,077 surgically and 1,098 nonsurgically treated patients with idiopathic scoliosis. Univariate analysis showed both patient- and hospital-level variables as strongly associated with surgical versus nonsurgical treatments and outcomes. Multivariate analysis revealed that Caucasians and private insurance patients were more likely to undergo surgical treatment (p<.05) even when controlling for comorbidities. Additionally, Caucasians had a reduced risk of nonroutine discharge compared with non-Caucasians (p=.03). Large hospitals had higher surgery rates (p=.08) than small- or medium-sized facilities and a lower risk of mortality (p=.04). Caucasians (65.1%) were more commonly admitted to large teaching hospitals than African American (59.8%) or Hispanic (41.8%) patients., Conclusions: Differences were found in the selection of surgical versus nonsurgical treatments, as well as inhospital morbidity for hospitalized idiopathic scoliosis patients based on ethnic and socioeconomic variables. This may in part be because of differences in access to the resources of large teaching hospitals for different ethnic and socioeconomic groups or variability in severity of scoliosis among these groups that was not captured in this database., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Object: In thoracolumbar deformity surgery, anterior-only approaches are used for reconstruction of anterior column failures. It is generally advised that vertebral body replacements (VBRs) should be preloaded by compression. However, little is known regarding the impact of different techniques for generation of preloads and which surgical principle is best for restoration of lordosis. Therefore, the authors analyzed the effect of different surgical techniques to restore spinal alignment and lordosis as well as the ability to generate axial preloads on VBRs in anterior column reconstructions., Methods: The authors performed a laboratory study using 7 fresh-frozen specimens (from T-3 to S-1) to assess the ability for lordosis reconstruction of 5 techniques and their potential for increasing preloads on a modified distractable VBR in a 1-level thoracolumbar corpectomy. The testing protocol was as follows: 1) Radiographs of specimens were obtained. 2) A 1-level corpectomy was performed. 3) In alternating order, lordosis was applied using 1 of the 5 techniques. Then, preloads during insertion and after relaxation using the modified distractable VBR were assessed using a miniature load-cell incorporated in the modified distractable VBR. The modified distractable VBR was inserted into the corpectomy defect after lordosis was applied using 1) a lamina spreader; 2) the modified distractable VBR only; 3) the ArcoFix System (an angular stable plate system enabling in situ reduction); 4) a lordosizer (a customized instrument enabling reduction while replicating the intervertebral center of rotation [COR] according to the COR method); and 5) a lordosizer and top-loading screws ([LZ+TLS], distraction with the lordosizer applied on a 5.5-mm rod linked to 2 top-loading pedicle screws inserted laterally into the vertebra). Changes in the regional kyphosis angle were assessed radiographically using the Cobb method., Results: The bone mineral density of specimens was 0.72 ± 22.6 g/cm(2). The maximum regional kyphosis angle reconstructed among the 5 techniques averaged 9.7°-16.1°, and maximum axial preloads averaged 123.7-179.7 N. Concerning correction, in decreasing order the LZ+TLS, lordosizer, and ArcoFix System outperformed the lamina spreader and modified distractable VBR. The order of median values for insertion peak load, from highest to lowest, were lordosizer, LZ+TLS, and ArcoFix, which outperformed the lamina spreader and modified distractable VBR. In decreasing order, the axial preload was highest with the lordosizer and LZ+TLS, which both outperformed the lamina spreader and the modified distractable VBR. The technique enabling the greatest lordosis achieved the highest preloads. With the ArcoFix System and LZ+TLS, compression loads could be applied and were 247.8 and 190.6 N, respectively, which is significantly higher than the insertion peak load and axial preload (p < 0.05)., Conclusions: Including the ability for replication of the COR in instruments designed for anterior column reconstructions, the ability for lordosis restoration of the anterior column and axial preloads can increase, which in turn might foster fusion.

Study Design: Retrospective study of a consecutive series of patients treated for proximal junctional kyphosis (PJK) of the upper thoracic and cervicothoracic spine., Objective: To discuss corrective techniques for the management of symptomatic kyphosis at the junction of fused and mobile segments of the upper thoracic and cervicothoracic spine in patients who complain of pain, neurological deficit, ambulatory difficulty, and/or social isolation., Summary of Background Data: PJK is an unfortunately common, but important, complication seen in long instrumented fusions to the upper thoracic and cervicothoracic spine. Although often asymptomatic, its incidence and prevalence warrant a discussion on treatment options for symptomatic patients., Methods: After the institutional review board confirmed approval, we retrospectively analyzed patients who received treatment of PJK from 2003 to 2009. Segmental instrumentation and intraoperative neurophysiological monitoring were used in all patients. Data acquisition was performed by reviewing electronic medical records and radiographs. Inclusion criteria were patients who underwent surgical correction of PJK of the cervicothoracic and upper thoracic spine and had more than 2-year follow-up. Preoperative lumbar lordosis, preoperative thoracic kyphosis, pre- and postoperative sagittal balance, and sagittal proximal junctional Cobb angle were obtained. All corrective procedures were performed in 2 stages, each patient receiving cervical traction between cases., Results: Inclusion criteria were met in 7 patients (5 women and 2 men), with mean age of 55 years (range, 18-80 years). Six patients received multilevel Smith-Petersen osteotomies, with 2 patients receiving rib osteotomies, and 1 patient received a vertebral column resection. The mean preoperative and postoperative proximal junctional Cobb angles were 45° (range, 14°-89.7°) and 14° (range, 3.0°-38.0°), respectively. The mean degree of correction was 31° (range, 11°-79.2°). All patients had maintained or improved sagittal balance. No patient sustained a temporary or permanent neurological deficit after correction related to surgery. All patients had 2-year follow-up, and there were no mortalities., Conclusion: For a selected cohort of patients who develop PJK of the upper thoracic and cervicothoracic spine, osteotomies, cervical traction, and intraoperative manual reduction provide a significant improvement of proximal junctional Cobb angles. To our knowledge, this is the first study to address treatment for symptomatic patients with this condition.

Tissue engineering strategies for intervertebral disc repair have focused on the use of autologous disc-derived chondrocytes. Difficulties with graft procurement, harvest site morbidity, and functionality, however, may limit the utility of this cell source. We used an in vivo porcine model to investigate allogeneic non-disc-derived chondrocytes and allogeneic mesenchymal stem cells (MSCs) for disc repair. After denucleation, lumbar discs were injected with either fibrin carrier alone, allogeneic juvenile chondrocytes (JCs), or allogeneic MSCs. Discs were harvested at 3, 6, and 12 months, and cell viability and functionality were assessed qualitatively and quantitatively. JC-treated discs demonstrated abundant cartilage formation at 3 months, and to a lesser extent at 6 and 12 months. For the carrier and MSC-treated groups, however, there was little evidence of proteoglycan matrix or residual notochordal/chondrocyte cells, but rather a type I/II collagen-enriched scar tissue. By contrast, JCs produced a type II collagen-rich matrix that was largely absent of type I collagen. Viable JCs were observed at all time points, whereas no evidence of viable MSCs was found. These data support the premise that committed chondrocytes are more appropriate for use in disc repair, as they are uniquely suited for survival in the ischemic disc microenvironment.

Object: As the population continues to age, relatively older geriatric patients will present more frequently with complex spinal deformities that may require surgical intervention. To the authors' knowledge, no study has analyzed factors predictive of complications after major spinal deformity surgery in the very elderly (75 years and older). The authors' objective was to determine the rate of minor and major complications and predictive factors in patients 75 years of age and older who underwent major spinal deformity surgery requiring a minimum 5-level arthrodesis procedure., Methods: Twenty-one patients who were 75 years of age or older and underwent thoracic and/or lumbar fixation and arthrodesis across 5 or more levels for spinal deformity were analyzed retrospectively. The medical and surgical records were reviewed in detail. Age, diagnosis, comorbidities, operative data, hospital data, major and minor complications, and deaths were recorded. Factors predictive of perioperative complications were identified by logistic regression analysis., Results: The mean patient age was 77 years old (range 75-83 years). There were 14 women and 7 men. The mean follow-up was 41.2 months (range 24-81 months). Fifteen patients (71%) had at least 1 comorbidity. A mean of 10.5 levels were fused (range 5-15 levels). Thirteen patients (62%) had at least 1 perioperative complication, and 8 (38%) had at least one major complication for a total of 17 complications. There were no perioperative deaths. Increasing age was predictive of any perioperative complication (p = 0.03). However, major complications were not predicted by age or comorbidities as a whole. In a subset analysis of comorbidities, only hypertension was predictive of a major complication (OR 10, 95% CI 1.3-78; p = 0.02). Long-term postoperative complications occurred in 11 patients (52%), and revision fusion surgery was necessary in 3 (14%)., Conclusions: Patients 75 years and older undergoing major spinal deformity surgery have an overall perioperative complication rate of 62%, with older age increasing the likelihood of a complication, and a long-term postoperative complication rate of 52%. Patients in this age group with a history of hypertension are 10 times more likely to incur a major perioperative complication. However, the mortality risk for these patients is not increased.

Object: The elderly population (age > 60 years) is the fastest-growing age group in the US. Spinal deformity is a major problem affecting the elderly and, therefore, the demand for surgery for spinal deformity is becoming increasingly prevalent in elderly patients. Much of the literature on surgery for adult deformity focuses on patients who are younger than 60 years, and therefore there is limited information about the complications and outcomes of surgery in the elderly population. In this study, the authors undertook a review of the literature on spinal deformity surgery in patients older than 60 years. The authors discuss their analysis with a focus on outcomes, complications, discrepancies between individual studies, and strategies for complication avoidance., Methods: A systematic review of the MEDLINE and PubMed databases was performed to identify articles published from 1950 to the present using the following key words: "adult scoliosis surgery" and "adult spine deformity surgery." Exclusion criteria included patient age younger than 60 years. Data on major Oswestry Disability Index (ODI) scores, visual analog scale (VAS) scores, patient-reported outcomes, and complications were recorded., Results: Twenty-two articles were obtained and are included in this review. The mean age was 74.2 years, and the mean follow-up period was 3 years. The mean preoperative ODI was 48.6, and the mean postoperative reduction in ODI was 24.1. The mean preoperative VAS score was 7.7 with a mean postoperative decrease of 5.2. There were 311 reported complications for 815 patients (38%) and 5 deaths for 659 patients (< 1%)., Conclusions: Elderly patient outcomes were inconsistent in the published studies. Overall, most elderly patients obtained favorable outcomes with low operative mortality following surgery for adult spinal deformity.

Object: Recently, the minimally invasive, lateral retroperitoneal, transpsoas approach to the thoracolumbar spinal column has been described by various authors. This is known as the minimally invasive lateral lumbar interbody fusion. The purpose of this study is to elucidate the approach-related morbidity associated with the minimally invasive transpsoas approach to the lumbar spine. To date, there have been only a couple of reports regarding the morbidity of the transpsoas muscle approach., Methods: A nonrandomized, prospective study utilizing a self-reported patient questionnaire was conducted between January 2006 and June 2008 at Northwestern University. Data were collected in 53 patients with a follow-up period ranging from 6 months to 3.5 years. Only 2 patients were lost to follow-up., Results: Thirty-six percent (19 of 53) of patients reported subjective hip flexor weakness, 25% (13 of 53) anterior thigh numbness, and 23% (12 of 53) anterior thigh pain. However, 84% of the 19 patients reported complete resolution of their subjective hip flexor weakness by 6 months, and most experienced improved strength by 8 weeks. Of those reporting anterior thigh numbness and pain, 69% and 75% improved to their baseline function by the 6-month follow-up evaluations, respectively. All patients with self-reported subjective hip flexor weakness underwent examinations during subsequent clinic visits after surgery; however, these examinations did not confirm a motor deficit less than Grade 5. Subset analysis showed that the L3-4 and L4-5 levels were most often affected., Conclusions: The minimally invasive, transpsoas muscle approach to the lumbar spine has a number of advantages. The data show that a percentage of the patients undergoing the transpsoas approach will have temporary sensory and motor symptoms related to this approach. The majority of the symptoms are thought to be related to psoas muscle inflammation and/or stretch injury to the genitofemoral nerve due to the surgical corridor traversed during the operation. No major injuries to the lumbar plexus were encountered. It is important to educate patients prior to surgery of the possibility of these largely transient symptoms.