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Objective: To investigate the biomechanical properties of pedicle screw reinsertion along the same trajectory in a previously validated synthetic bone model., Methods: Twenty identical acrylonitrile butadiene styrene models of lumbar vertebrae were three-dimensional-printed. Screws were placed in the standard fashion into each pedicle. Models were separated into 2 equal groups, control and experimental. Experimental group screws were completely removed from their testing block and reinserted once. All screws in both groups were then forcibly removed. Continuous torque monitoring was collected on screw insertion torque (IT), removal torque, and reinsertion torque. Pullout strength (PO), screw stiffness (STI), and strain energy (STR) were calculated., Results: There was no significant difference between control and experimental groups for PO (P = 0.26), STI (P = 0.55), STR (P = 0.50), or IT (P = 0.24). There was a significant decrease in reinsertion torque (54.5 N-cm ± 8.2 N-cm) from control IT (62.9 N-cm ± 8.4 N-cm, P = 0.045) and experimental IT (67.5 N-cm ± 7.6 N-cm, P = 0.0026). Strong correlations (Pearson's r > 0.80) were seen between control IT against STR and PO, between each of the experimental torque measurements, and between experimental PO and STI., Conclusions: Despite a significant decrease in insertion torque, there is no significant loss of pedicle screw performance when a screw is removed and reinserted along the same trajectory., (Copyright © 2024. Published by Elsevier Inc.)

Objective: Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been demonstrated to achieve the highest rates of arthrodesis in multilevel lumbar fusion but is also associated with possible perioperative morbidity. A novel allograft (OSTEOAMP) is a differentiated allograft that retains growth factors supporting bone healing. The authors sought to compare the clinical and radiographic outcomes of rhBMP-2 and the novel allograft in lumbar interbody arthrodesis to determine if the latter may be a safer and equally effective alternative to rhBMP-2 for single- and multilevel posterior or transforaminal lumbar interbody fusion (PLIF or TLIF)., Methods: Patients who underwent single- or multilevel TLIF or PLIF using either OSTEOAMP or rhBMP-2 at the authors' institution over a 2-year period were prospectively followed for 12 months. Healthcare utilization, safety measures, patient satisfaction, physical disability (measured on the Oswestry Disability Index [ODI]), back and leg pain (on the numeric rating scale [NRS]), quality of life (on the EQ-5D scale), and return to work (RTW) were prospectively recorded. For purposes of this study, this consecutive series was retrospectively analyzed and pseudarthrosis rates were assessed at 2 years of follow-up. All patients (100%) had both 12-month patient-reported outcome follow-up and 24-month clinical and radiographic follow-up., Results: One thousand one hundred fifty-four patients (654 treated with OSTEOAMP, 500 with rhBMP-2) were prospectively enrolled in the institutional registry. After propensity score matching, there were no significant baseline differences between 330 novel allograft and 330 rhBMP-2 cases. Perioperative morbidity and 90-day hospital readmission (3.3% vs 2.4%, p = 0.485) did not significantly differ between the novel allograft and the rhBMP-2 cases. At the 2-year follow-up, symptomatic pseudarthrosis requiring revision surgery occurred in 8 patients (2.4%) with OSTEOAMP and 6 patients (1.8%) with rhBMP-2 (p = 0.589). The overall fusion rate at 2 years was similar between groups (p = 0.213). Both groups showed significant and equivalent improvement in patient-reported outcome measures (PROMs) from baseline to 12-month follow-up, with no significant difference in 1-year mean NRS leg pain score (2.5 vs 2.7), ODI (25 vs 26), quality-adjusted life years (0.73 vs 0.73), satisfaction (83% vs 80%), or RTW (6.6 vs 7 weeks)., Conclusions: In the authors' institutional experience, OSTEOAMP is a clinically viable substitute for rhBMP-2 for single- and multilevel lumbar fusion. This novel allograft provides clinically effective arthrodesis and improvements in PROMs comparable to rhBMP-2 with a similar safety profile. Additional indications and outcome assessment in longitudinal studies are needed to further characterize this allogeneic graft.

Objective: The impact of mental health comorbidities on outcomes after lumbar spine surgery in workers' compensation (WC) patients has not been robustly explored. The goal of this study was to examine the impact of mental health comorbidities on pain, disability, quality of life, and return to work after lumbar spine surgery in WC patients., Methods: A nationwide, prospective surgical outcomes registry (National Neurosurgery Quality Outcomes Database [N2QOD]) was queried for all patients who underwent 1- to 4-level lumbar decompression and/or fusion from 2012 to 2021. Patients were stratified on the basis of compensation status into non-WC (25,507) and WC (1018) cohorts. Baseline demographic data, perioperative safety data, and patient-reported outcome measures were compared between groups. The WC cohort was further subdivided on the basis of mental health status into patients with anxiety and depression (n = 107) and those without anxiety and depression (n = 911). Propensity matching was used to generate parity between these subgroups, generating 214 patients (107 pairs) for analysis. Perioperative safety, facility utilization, 1-year patient-reported outcomes (back and leg pain, disability, and quality of life), and return to work were measured as a function of WC and mental health comorbidity status., Results: A total of 26,525 patients (25,507 non-WC and 1018 WC) who underwent 1- to 4-level lumbar spine surgery were reviewed. WC patients were younger, healthier (lower American Society of Anesthesiologists class), more likely to be minorities, less educated, and more likely to smoke and had greater baseline back pain, disability, and quality of life compared to non-WC patients. The prevalence of anxiety and depression was similar between groups (11%). WC patients had worse outcomes for all measures and lower rates of return to work compared to non-WC patients. WC patients with anxiety and depression demonstrated even greater disparities in all outcomes. After propensity matching, WC patients with anxiety and depression continued to demonstrate significantly worse outcomes in comparison to WC patients without anxiety and depression., Conclusions: Disparities in outcomes after lumbar spine surgery in WC patients are exacerbated in patients with anxiety and depression. WC patients with mental health comorbidities receive the least benefit from lumbar spine surgery and may represent the most vulnerable subset of patients with spine pathology. Addressing mental health comorbidities preoperatively may represent an opportunity for valuable resource allocation and surgical optimization in the WC population.

Purpose: Bibliometric analyses have gained popularity for studying scientific literature, but their application to evaluate technological literature (patents) remains unexplored. We conducted a bibliometric analysis on the top 100 most-cited patents in scoliosis surgery., Methods: Multiple databases were queried using The Lens to identify the top 100 scoliosis surgery patents, which were selected based on forward patent citations. These patents were then categorized into 8 groups based on technological descriptors and assessed based on various factors including earliest priority date, year issued, and expiration status., Results: The top 100 most-cited patents included technology underlying anterolateral tethering and distraction systems (n = 11), posterior tethering and distraction systems (n = 23), posterior segmental bone anchor and rod engagement systems (n = 29), interbody devices (n = 10), biological and electrophysiological agents for scoliosis treatment and/or improved arthrodesis (n = 8), intraoperative arthroplasty devices (n = 5), orthotic devices (n = 12), and implantable devices for non-invasive, postoperative alterations of skeletal alignment (n = 2). Seventy-five patents were expired, 21 are still active, and 4 were listed as inactive. The late 1970s and early 2000s saw increased numbers of patent filings. Demonstrated trends showed no meaningful correlation between patent rank and earliest priority date (linear trendline y = 0.2648x - 477.27; R 2  = 0.0114), while a very strong correlation was found between patent rank and citations per year (power trendline y = 118.82x --0.83 ; R 2  = 0.8983)., Conclusion: Patent bibliometric analyses in the field of spinal deformity surgery provide a means to assess past advancements, better understand what it takes to make a difference in the field, and to potentially facilitate the development of innovative technologies in the future. The method described is a reliable and reproducible technique for evaluating technological literature in our field., (© 2023. The Author(s), under exclusive licence to Scoliosis Research Society.)

Objective: Firearm-related injuries and deaths are an endemic problem in the US, posing a burden on the healthcare system with significant social and economic consequences. As front-line care providers for these patients, neurosurgeons are both knowledgeable about these injuries and credible messengers in the public discussion of ways to reduce firearm injuries. The purpose of this study was to explore US-based neurosurgeons' views and behaviors regarding firearms to understand and define a potential role for neurosurgical organizations in advocacy efforts to reduce firearm death and injuries., Methods: The authors conducted an anonymous survey of US neurosurgeons using the American Association of Neurological Surgeons (AANS) member database from April to June 2023. The 22-question survey included questions related to firearm ownership, personal views on firearms, and support for both general and policy-specific advocacy efforts to reduce firearm deaths and injuries., Results: The survey response rate was 20.7%, with 1568 of the 7587 members invited completing the survey. The survey completion rate was 93.4%, with 1465 of the 1568 surveys completed and included in this analysis. The majority of respondents were male (raw: 81.7%; weighted 81.1%), White (raw: 69.7%; weighted 70.2%), and older than 50 years (raw: 56.2%; weighted: 54%). Most respondents reported treating patients with firearm injuries (raw: 83.3%; weighted: 82%), 85.5% (weighted: 85.1%) had used a firearm, and 42.4% (weighted: 41.5%) reported owning a firearm. Overall, 78.8% (weighted: 78.7%) of respondents felt that organized neurosurgery should participate in advocacy efforts. When examining individual policies, those that restrict the acquisition of firearms garnered the support of at least 65% of respondents, while nonrestrictive policies were supported by more than 75% of respondents. Free-text responses provided insight into both motivations for and objections to organizational advocacy., Conclusions: The majority of US-based neurosurgeons support involvement in advocacy efforts to reduce firearm deaths and injuries. Themes expressed by members both supporting and objecting to advocacy provide insight into approaches that could ensure broad support. Neurosurgical organizations such as the AANS and Congress of Neurological Surgeons may use the results of this survey to make informed decisions regarding involvement in advocacy efforts on behalf of their membership to lessen the burden of firearm injury in the US.

Background: Ambulatory surgery centers (ASCs) have emerged as an alternative setting for surgical care as part of the national effort to lower health care costs. The literature regarding the safety of minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) in the ASC setting is limited to few small case series., Objective: To assess the safety and efficacy of MIS TLIF performed in the ASC vs inpatient hospital setting., Methods: A total of 775 patients prospectively enrolled in the Quality Outcomes Database undergoing single-level MIS TLIF at a single ASC (100) or the inpatient hospital setting (675) were compared. Propensity matching generated 200 patients for analysis (100 per cohort). Demographic data, resource utilization, patient-reported outcome measures (PROMs), and patient satisfaction were assessed., Results: There were no significant differences regarding baseline demographic data, clinical history, or comorbidities after propensity matching. Only 1 patient required inpatient transfer from the ASC because of intractable pain. All other patients were discharged home within 23 hours of surgery. The rates of 90-day readmission (2.0%) and reoperation (0%) were equivalent between groups. Both groups experienced significant improvements in all PROMs (Oswestry Disability Index, EuroQol-5D, back pain, and leg pain) at 3 months that were maintained at 1 year. PROMs did not differ between groups at any time point. Patient satisfaction was similar between groups at 3 and 12 months after surgery., Conclusion: In carefully selected patients, MIS TLIF may be performed safely in the ASC setting with no statistically significant difference in safety or efficacy in comparison with the inpatient setting., (Copyright © Congress of Neurological Surgeons 2023. All rights reserved.)

Background: Anterior cervical discectomy and fusion (ACDF) and posterior cervical foraminotomy (PCF) are the most common surgical approaches for medically refractory cervical radiculopathy. Rigorous cost-effectiveness studies comparing ACDF and PCF are lacking., Objective: To assess the cost-utility of ACDF vs PCF performed in the ambulatory surgery center setting for Medicare and privately insured patients at 1-year follow-up., Methods: A total of 323 patients who underwent 1-level ACDF (201) or PCF (122) at a single ambulatory surgery center were compared. Propensity matching generated 110 pairs (220 patients) for analysis. Demographic data, resource utilization, patient-reported outcome measures, and quality-adjusted life-years were assessed. Direct costs (1-year resource use × unit costs based on Medicare national allowable payment amounts) and indirect costs (missed workdays × average US daily wage) were recorded. Incremental cost-effectiveness ratios were calculated., Results: Perioperative safety, 90-day readmission, and 1-year reoperation rates were similar between groups. Both groups experienced significant improvements in all patient-reported outcome measures at 3 months that was maintained at 12 months. The ACDF cohort had a significantly higher preoperative Neck Disability Index and a significantly greater improvement in health-state utility (ie, quality-adjusted life-years gained) at 12 months. ACDF was associated with significantly higher total costs at 1 year for both Medicare ($11 744) and privately insured ($21 228) patients. The incremental cost-effectiveness ratio for ACDF was $184 654 and $333 774 for Medicare and privately insured patients, respectively, reflecting poor cost-utility., Conclusion: Single-level ACDF may not be cost-effective in comparison with PCF for surgical management of unilateral cervical radiculopathy., (Copyright © Congress of Neurological Surgeons 2023. All rights reserved.)

Objective: Patients with workers' compensation (WC) claims are reported to demonstrate poorer surgical outcomes after lumbar spine surgery. However, outcomes after anterior cervical discectomy and fusion (ACDF) in WC patients remain debatable. The authors aimed to compare outcomes between a propensity score-matched population of WC and non-WC patients who underwent ACDF., Methods: Patients who underwent 1- to 4-level ACDF were retrospectively reviewed from the prospectively maintained Quality Outcomes Database (QOD). After propensity score matching, 1-year patient satisfaction, physical disability (Neck Disability Index [NDI]), pain (visual analog scale [VAS]), EQ-5D, and return to work were compared between WC and non-WC cohorts., Results: A total of 9957 patients were included (9610 non-WC and 347 WC patients). Patients in the WC cohort were significantly younger (50 ± 9.1 vs 56 ± 11.4 years, p < 0.001), less educated, and were more frequently male, non-Caucasian, and active smokers (29.1% vs 18.1%, p < 0.001), with greater baseline VAS and NDI scores and poorer quality of life (p < 0.001). One-year postoperative improvements in VAS, NDI, EQ-5D, and return-to-work rates and satisfaction were all significantly worse for WC compared with non-WC patients. After adjusting for baseline differences via propensity score matching, WC versus non-WC patients continued to demonstrate worse 3- and 12-month VAS neck pain and NDI (p = 0.010), satisfaction (χ2 = 4.03, p = 0.045), and delayed return to work (9.3 vs 5.7 weeks, p < 0.001)., Conclusions: WC status was associated with greater 1-year residual disability and axial pain along with delayed return to work, without any difference in quality of life despite having fewer comorbidities and being a younger population. Further studies are needed to determine the societal impact that WC claims have on healthcare delivery in the setting of ACDF.

Objective: Workers' compensation (WC) and litigation have been shown to adversely impact prognoses in a vast range of health conditions. Low-back pain is currently the most frequent reason for WC claims. The objective of this study was to conduct the largest propensity-matched comparison of outcomes between patients with WC and non-WC status who underwent lumbar spinal decompression with and without fusion., Methods: Complete data sets for patients who underwent 1- to 4-level lumbar spinal fusion or decompression alone were retrospectively retrieved from the Quality Outcomes Database (QOD), which included 1-year patient-reported outcomes from more than 200 hospital systems collected from 2012 to 2021. Population demographics, perioperative safety, facility utilization, patient satisfaction, disability, pain, EQ-5D quality of life, and return to work (RTW) rates were compared between cohorts for both subgroups. Statistical significance was set at p < 0.05., Results: There were 29,652 patients included in the study. Laminectomy was performed in 16,939 with non-WC status and in 615 with WC, whereas fusion was performed in 11,767 with non-WC status and in 331 with WC. WC patients were more frequently male, a minority race, younger, less educated, more frequently a smoker, had a healthier American Society of Anesthesiologists grade, and with greater baseline visual analog scale (VAS) and Oswestry Disability Index (ODI) scores (p < 0.001). One-year postoperative improvements in VAS, ODI, quality-adjusted life years (QALYs), RTW rates, and satisfaction were all significantly worse for WC versus non-WC patients for both procedures. After adjusting for baseline differences via propensity matching, WC versus non-WC patients continued to demonstrate worse 3- and 12-month VAS and ODI scores, reduced 12-month QALY gain, and delayed RTW after both procedure types., Conclusions: WC status was associated with significantly greater residual disability and pain postoperatively, a lower quality of life, and delayed RTW. Utilizing resources to identify the negative influences on outcomes for WC patients may be valuable in preoperative optimization and could yield better outcomes in these patients.

Background: Bibliometric analyses of the scientific literature have grown increasingly popular in the past few decades. However, patent bibliometric studies, evaluation of technological literature, have not yet been applied in neurosurgery., Objective: To perform a pilot patent bibliometric analysis of the top 100 most cited patents in cranial neurosurgery., Methods: The Lens was used to query multiple databases, to select the top 100 cranial neurosurgical patents based upon forward patent citations. These were organized into 9 categories based on technological descriptors and were evaluated based on the earliest priority date, year issued, and expiration status, among others., Results: The top 100 most cited patents included technology underlying 3D navigation (n = 31), pharmacology and implants (n = 20), vascular occlusion (n = 5), craniotomy closure (n = 9), focal lesioning and tissue resection (n = 8), brain and systemic cooling (n = 5), neuroendoscopy (n = 8), neuromonitoring and stimulation (6), and technologies improving surgeon performance (n = 8). Ninety-six patents were filed in the United States, 72 were expired, 19 are still active, and 9 were listed as inactive. The highest number of patents was applied for from the mid-1990s to the mid-2000s. Demonstrated trends showed no meaningful correlation between patent rank and earliest priority date (linear trendline y = 0.7107 x -1367.5; R 2  = 0.0671), while a very strong correlation was found between patent rank and citations per year (power trendline y = 127.93 x -1.094; R 2  = 0.8579)., Conclusions: Patent bibliometrics allow evaluation of neurosurgical advancements from the past and enable subsequent development of cutting-edge technology in the future. The described method is a reproducible and reliable technique for evaluating our field's patent literature., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Study Design: Retrospective analysis of prospectively collected data., Objective: Assess the cost-utility of anterior cervical discectomy and fusion (ACDF) performed in the ambulatory surgery center (ASC) versus inpatient hospital setting for Medicare and privately insured patients at one-year follow-up., Summary of Background Data: Outpatient ACDF has gained popularity due to improved safety and reduced costs. Formal cost-utility studies for ambulatory versus inpatient ACDF are lacking, precluding an accurate assessment of cost-effectiveness., Materials and Methods: A total of 6504 patients enrolled in the Quality Outcomes Database (QOD) undergoing one-level to two-level ACDF at a single ASC (520) or the inpatient hospital setting (5984) were compared. Propensity matching generated 748 patients for analysis (374 per cohort). Demographic data, resource utilization, patient-reported outcome measures, and quality-adjusted life-years (QALYs) were assessed. Direct costs (1-year resource use×unit costs based on Medicare national allowable payment amounts) and indirect costs (missed workdays×average US daily wage) were recorded. Incremental cost-effectiveness ratios were calculated., Results: Complication rates and improvements in patient-reported outcome measures and QALYs were similar between groups. Ambulatory ACDF was associated with significantly lower total costs at 1 year for Medicare ($5879.46) and privately insured ($12,873.97) patients, respectively. The incremental cost-effectiveness ratios for inpatient ACDF was $3,674,662 and $8,046,231 for Medicare and privately insured patients, respectively, reflecting unacceptably poor cost-utility., Conclusion: Inpatient ACDF is associated with significant increases in total costs compared to the ASC setting without a safety, outcome, or QALY benefit. The ASC setting is a dominant option from a health economy perspective for first-time one-l to two-level ACDF in select patients compared to the inpatient hospital setting., Competing Interests: The authors report no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Most existing anterior cervical discectomy and fusion (ACDF) outcome studies omit emergency department (ED) use. To our knowledge, this study on ED use following ACDF surgery is the first to use a direct patient chart review and the first to include revision patients, 1-5 levels of ACDFs, and performance of corpectomy in the analysis. This study examines the frequency and basis of hospital service use within 30 days of ACDF surgery, specifically ED visits, hospital readmissions, and returns to the operating room. A retrospective chart review was performed for 1273 consecutive patients who underwent ACDF surgery at one institution from July 2013 to June 2016. Of the 1273 patients with ACDF, 97 (7.6%) presented to the ED within 30 days after surgery. Of 43 patients with revision ACDF, 9 (20.9%) returned to the ED, compared with 88 (7.2%) of 1230 patients with primary ACDF (P = 0.001). Of the 111 ED visits by 97 patients, 40 (36%) were for cervicalgia, 13 (12%) were for dysphagia, 8 (7%) were for trauma, 7 (6%) were for nausea, 4 (4%) were for medication refill, 3 (3%) were for dehiscence, 3 (3%) were for pneumonia, and 3 (3%) were for urinary tract infection. Of the ED presentations, 8 (7%) occurred during the first 2 days after surgery, and 46 (41%) occurred within the first postoperative week., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Pedicle screws provide superior fixation of the subaxial cervical spine to other techniques. However, a high degree of accuracy is required for safe placement given the proximity of pedicles to critical neurovascular structures. A variety of techniques are described to maximize accuracy, including freehand, fluoroscopy-guided, and neuronavigation-based methods.  We present a technique for the placement of pedicle screws in the subaxial cervical spine using direct visualization of the pedicle in a patient who required an occipito-cervical fusion construct in the setting of a C2 chordoma. A laminotomy or laminectomy is performed laterally to allow for visualization of the medial, superior, and inferior walls of the pedicle. The entry point for screw placement is determined based on pedicle anatomy and is typically 1 to 2 mm lateral to the midpoint of the lateral mass, just below the base of the superior articulating process. Screw trajectory is determined by visualizing the pedicle borders and is aimed at the junction of the medial pedicle wall, with the posterior vertebral body down the pedicle axis. Tactile feedback (loss of resistance) is used to assess for a breach while drilling. The cannulation is then tapped, and the screw is placed in a standard fashion.  Direct visualization of pedicle anatomy can be a useful adjunct to guide the safe placement of subaxial pedicle screws when superior fixation is required or when normal anatomy is distorted. The technique may be combined with fluoroscopic or navigation-based techniques to provide real-time anatomic guidance during screw placement. The patient provided informed, written consent for this procedure before surgery. Used with permission from Barrow Neurological Institute, Phoenix, Arizona., (© Congress of Neurological Surgeons 2021.)

Background: Obtaining successful arthrodesis at the craniocervical junction and atlantoaxial joint can be more challenging than in other segments of the cervical spine. This challenge stems from the relatively hypermobile joints between the occipital condyles, the motion that occurs at C1 and C2, as well as the paucity of dorsal bony surfaces for posterior arthrodesis. While multiple different techniques for spinal fixation in this region have been well described, there has been little investigation into auxiliary methods to improve fusion rates., Objective: To describe the use of an occipital bone graft to augment bony arthrodesis in the supraaxial cervical spine using a multidisciplinary approach., Methods: We review the technique for harvesting and placing a vascularized occipital bone graft in 2 patients undergoing revision surgery at the craniocervical junction., Results: The differentiation from nonvascularized bone graft, either allograft or autograft, to a bone graft using vascularized tissue is a key principle of this technique. It has been well established that vascularized bone heals and fuses in the spine better than structural autogenous grafts. However, the morbidity and added operative time of harvesting a vascularized flap, such as from the fibula or rib, precludes its utility in most degenerative spine surgeries., Conclusion: By adapting the standard neurosurgical procedure for a suboccipital craniectomy and utilizing the tenets of flap-based reconstructive surgery to maintain the periosteal and muscular blood supply, we describe the feasibility of using a vascularized and pedicled occipital bone graft to augment instrumented upper cervical spinal fusion. The use of this vascularized bone graft may increase fusion rates in complex spine surgeries., (© Congress of Neurological Surgeons 2021.)

Background: Solid arthrodesis is the long-term goal of most spinal reconstruction surgeries. A multitube of biologics as well as autograft is commonly used to augment the bony fusion. Medial scapular vascularized bone grafts (S-VBGs) are a novel approach to supplement cervicothoracic arthrodesis in patients at high risk for failed fusion., Objective: To discuss the benefits of using a vascularized scapular graft, pedicled to the rhomboid minor, compared to both nonvascularized bone grafts and free vascularized bone grafts, as well as the surgical technique, feasibility, and nuances of the surgical experience with an S-VBG., Methods: The anatomic feasibility of this procedure has been established in cadaver studies. This technical note details the operative steps and presents the first surgery in which a vascularized scapular graft was used to supplement cervicothoracic arthrodesis., Results: A single patient with complex cervical deformity was successfully treated with this novel arthrodesis approach., Conclusion: Vascularized scapula grafts, pedicled on the rhomboid minor, provides both structural support and a source of vascularized autograft to a cervicothoracic arthrodesis. It leverages the benefits of a free-flap bone with less operative time and morbidity., (© Congress of Neurological Surgeons 2021.)

Background: Pseudoarthrosis, or failure to achieve bony union, is a well-known complication of spinal fusion operations. Rates range from 5% to 40% and are influenced by both patient and technical factors. Patients who do not achieve complete fusion may experience a return or worsening of their preoperative pain. For patients with complicated pathologies, vascularized bone grafts (VBGs) have been shown to provide better outcomes than nonvascularized bone grafts (N-VBGs)., Objective: To enhance an instrumented spinal fusion by the innovative technique presented herein that utilizes a rotated, pedicled VBG from the left eighth rib under the paraspinous musculature into the midlumbar posterolateral gutter., Methods: For posterior approaches, the rib can be easily accessed and rotated into the appropriate strut position. The rib is dissected out, identifying and preserving the neurovascular bundle medially. The rib is then tunneled medially and appropriately positioned as the spinal graft, with the curve providing anatomic kyphosis or lordosis, depending on the surgical location. It is then successfully fixated with plates and spinal screws., Results: In our limited experience to date, vascularized rib grafting procedures augment fusion and reduce operating room time and bleeding compared to free flap procedures. No patients have experienced complications related to these grafts., Conclusion: Pedicled vascularized rib grafts can be utilized to provide the advantages of a vascularized bone flap in complicated pathologies requiring spinal fusion as far as the L2-L3 level, without the morbidity associated with free tissue transfer., (© Congress of Neurological Surgeons 2021.)

Objective: Anterior cervical discectomy and fusion (ACDF) is a common and robust procedure performed on the cervical spine. Literature on ACDF for 4 or more segments is sparse. Increasing the number of operative levels increases surgical complexity, tissue retraction, and risks of complications, particularly dysphagia. The overall risks of these complications and rates of dysphagia are not well studied for surgery on 4 or more segments. In this study, the authors evaluated their institution's perioperative experience with 4- and 5-level ACDFs., Methods: The authors retrospectively reviewed patients who underwent 4- or 5-level ACDF at their institution over a 6-year period (May 2013-May 2019). Patient demographics, perioperative complications, readmission rates, and swallowing outcomes were recorded. Outcomes were analyzed with a multivariate linear regression., Results: A total of 174 patients were included (167 had 4-level and 7 had 5-level ACDFs). The average age was 60.6 years, and 54.0% of patients (n = 94) were men. A corpectomy was performed in 12.6% of patients (n = 22). After surgery, 56.9% of patients (n = 99) experienced dysphagia. The percentage of patients with dysphagia decreased to 22.8% (37/162) at 30 days, 12.9% (17/132) at 90 days, and 6.3% (5/79) and 2.8% (1/36) at 1 and 2 years, respectively. Dysphagia was more likely at 90 days postoperatively in patients with gastroesophageal reflux (OR 4.4 [95% CI 1.5-12.8], p = 0.008), and the mean (± SD) lordosis change was greater in patients with dysphagia than those without at 90 days (19.8° ± 13.3° vs 9.1° ± 10.2°, p = 0.003). Dysphagia occurrence did not differ with operative implants, including graft and interbody type. The mean length of time to solid food intake was 2.4 ± 2.1 days. Patients treated with dexamethasone were more likely to achieve solid food intake prior to discharge (OR 4.0 [95% CI 1.5-10.6], p = 0.004). Postsurgery, 5.2% of patients (n = 9) required a feeding tube due to severe approach-related dysphagia. Other perioperative complication rates were uniformly low. Overall, 8.6% of patients (n = 15) returned to the emergency department within 30 days and 2.9% (n = 5) required readmission, whereas 1.1% (n = 2) required unplanned return to surgery within 30 days., Conclusions: This is the largest series of patients undergoing 4- and 5-level ACDFs reported to date. This procedure was performed safely with minimal intraoperative complications. More than half of the patients experienced in-hospital dysphagia, which increased their overall length of stay, but dysphagia decreased over time.

Several vascularized bone grafts (VBGs) have been introduced for reconstruction and augmenting fusion of the spine. The expanding use of VBGs in the field of spinoplastic reconstruction, however, has highlighted the need to clarify the nomenclature for bony reconstruction as well as establish the position of VBGs on the bony reconstructive algorithm. In the current literature, the terms "flap" and "graft" are often applied inconsistently when describing vascularized bone transfer. Such inconsistency creates barriers in communication between physicians, confusion in interpreting the existing studies, and difficulty in comparing surgical techniques. VBGs are defined as bone segments transferred on their corresponding muscular attachments without a named major feeding vessel. The bone is directly vascularized by the muscle attachments and unnamed periosteal feeding vessels. VBGs are best positioned as a separate entity in the bony reconstruction algorithm between nonvascularized bone grafts (N-VBGs) and bone flaps. VBGs offer numerous advantages as they supply fully vascularized bone to the recipient site without the microsurgical techniques or pedicle dissection required for raising bone flaps. Multiple VBGs have been introduced in recent years to optimize these benefits for spinoplastic reconstruction., Competing Interests: Conflict of Interest None declared., (Thieme. All rights reserved.)

Pseudarthrosis is a difficult complication often seen in patients with complex spinal pathology. To supplement existing neurosurgical approaches to cervicothoracic spinal instrumentation and fusion, novel vascularized rib bone grafts can be utilized in patients at high risk for failed spinal fusion. In this article, we discuss the indications, benefits, surgical technique, feasibility, and limitations of using rib vascularized rib bone grafts to augment spinal fusion., Competing Interests: Conflict of Interest Dr. Ropper receives consulting fees from Globus Medical and Stryker, but they have no conflict with this report., (Thieme. All rights reserved.)

Successful arthrodesis at the craniocervical junction and atlantoaxial joint can be more challenging than in other segments of the cervical spine. Different techniques for spinal fixation in this region have been well described, along with auxiliary methods to improve fusion rates. The occipital vascularized bone graft is a novel technique that can be used to augment bony arthrodesis in the supra-axial cervical spine. It provides the benefits of a vascularized autologous graft, such as accelerated healing, earlier fusion, and increased strength. This technique can be learned with relative ease and may be particularly helpful in cases with high risk of nonunion or pseudoarthrosis in the upper cervical spine., Competing Interests: Conflicts of Interest Dr. Ropper receives consulting fees from Globus Medical and Stryker. All authors, including Dr. Ropper, have no financial interests in relation to the content of this article., (Thieme. All rights reserved.)

Objective: Hospital readmission and the reduction thereof has become a major quality improvement initiative in organized medicine and neurosurgery. However, little research has been performed on why neurosurgical patients utilize hospital emergency rooms (ERs) with or without subsequent admission in the postoperative setting., Methods: This study was a retrospective, single-center review of data for all surgical cranial procedures performed from July 2013 to July 2016 in patients who survived to discharge. The study was approved by the institutional review board of the participating medical center., Results: The authors identified 7294 cranial procedures performed during 6596 hospital encounters in 5385 patients. The rate of postoperative ER utilization within 30 days after surgical hospitalization across all procedure types was 13.1 per 100 surgeries performed. The two most common chief complaints were pain (30.7%) and medical complication (18.2%). After identification of relevant surgical and patient factors with univariable analysis, a multivariable backward elimination logistic regression model was constructed in which Ommaya reservoir placement (OR 2.65, p = 0.0008) and cranial CSF shunt placement (OR 1.40, p = 0.0001) were associated with increased ER utilization. Deep brain stimulation electrode placement (OR 0.488, p = 0.0004), increasing hospital length of stay (OR 0.935, p < 0.0001), and increasing patient age (OR 0.988, p < 0.0001) were associated with lower rates of postoperative ER utilization. One-half (50%) of ER visit patients were readmitted to the hospital. New/worsening neurological deficit chief complaint (OR 1.99, p = 0.0088), fever chief complaint (OR 2.41, p = 0.0205), altered mentation chief complaint (OR 2.71, p = 0.0002), patient chronic kidney disease (OR 3.31, p = 0.0037), brain biopsy procedure type (OR 3.50, p = 0.0398), and wound infection chief complaint (OR 31.4, p = 0.0008) were associated with increased rates of readmission to the hospital from the ER in multivariable analysis., Conclusions: The authors report the rates of and reasons for ER utilization in a large cohort of postoperative cranial neurosurgical patients. Factors identified were associated with both increased and decreased use of the ER after cranial surgery, as well as variables associated with readmission to the hospital after postoperative ER visitation. These findings may direct future quality improvement via prospective implementation of care pathways for high-risk procedures.

Introduction: Neurosurgical guidelines recommend maintaining mean arterial pressure (MAP) between 85 and 90 mm Hg following acute spinal cord injury (SCI). In our hospital, SCI patients receive orders for MAP targeting for 72 hours following admission, but it is unclear how often the patient's MAP meets the target and whether or not this affects outcome. We hypothesized that the proportion of MAP measurements ≥85 mm Hg would be associated with neurologic recovery., Methods: Spinal cord injury patients with blunt mechanism of injury admitted between 2014 and 2019 were identified from the registry of a level 1 trauma center. Proportion of MAP values ≥85 mm Hg was calculated for each patient. Neurologic improvement, as measured by positive change in American Spinal Injury Association (ASIA) impairment scale by ≥1 level from admission to discharge was evaluated with respect to proportion of elevated MAP values., Results: A total of 136 SCI patients were evaluated. Average proportion of elevated MAP values was 75%. Admission ASIA grades were as follows: A, 30 (22.1%); B, 20 (14.7%); C, 28 (20.6%); and D, 58 (42.6%). One hundred six patients (77.9%) required vasopressors to elevate MAP (ASIA A, 86.7%; B, 95.0%; C, 92.9%; D, 60.3%). Forty patients (29.4%) were observed to have improvement in ASIA grade by discharge (admission ASIA A, 15%; B, 33%; C, 40%; D, 13%). The proportion of elevated MAP values was higher for patients with neurologic improvement (0.81 ± 0.15 vs. 0.72 ± 0.25, p = 0.014). Multivariate modeling demonstrated a significant association between proportion of elevated MAP values and neurologic improvement (p = 0.028). An interaction revealed this association to be moderated by vasopressor dose (p = 0.032)., Conclusion: The proportion of MAP measurements ≥85 mm Hg was determined to be an independent predictor of neurologic improvement. Increased vigilance regarding MAP maintenance above 85 mm Hg is warranted to optimize neurologic recovery following SCI., Level of Evidence: Therapeutic/care management, level IV., (Copyright © 2020 American Association for the Surgery of Trauma.)

Background: Neuromuscular electrical stimulation (NMES) has emerged as a viable alternative for venous thromboembolism prophylaxis. Electrical stimulation of the peroneal nerve using NMES may potentially interfere with somatosensory-evoked potential (SSEP) acquisition. This feasibility study evaluates a NMES device and its effect on SSEP acquisition as an initial step in a randomized clinical trial to assess NMES for intraoperative venous thromboembolism prophylaxis., Methods: Healthy volunteers underwent SSEP testing during NMES in an outpatient setting. Concurrently, SSEP recordings of the posterior tibial nerve with stimulation at each ankle were obtained in 3 conditions: sham, NMES in place but inactive; ipsi, NMES active on leg ipsilateral to SSEP acquisition; and contra, NMES active on the leg contralateral to SSEP acquisition. Nonparametric statistical methods, including repeated measures, were used for data analysis., Results: Stimulation intensities on the left, right, and bilaterally did not differ (P ≥ 0.20). Strong positive correlations were noted between the ipsilateral geko stimulus pulse width and ipsilateral SSEP stimulation intensities (left: r s  = 0.866, P = 0.001; right: r s  = 0.877, P = 0.001). Women required significantly greater pulse width settings than men (P = 0.01). Finally, visual inspection of waveforms, as used during dynamic IONM, did not show any significant variations of P37 cortical waveforms during NMES., Conclusions: As a preliminary step to testing NMES intraoperatively for venous thromboembolism prophylaxis, interference with SSEP acquisition was investigated in the outpatient laboratory setting. Within a small sample of healthy volunteers, no significant changes were seen in P37 cortical latencies to suggest interference between the NMES device and SSEP waveforms., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Many institutions have developed shared decision-making conferences as a mechanism for reducing treatment costs and improving patient outcomes. Little is known about the process of shared decision-making that takes place in these conferences, and there is the possibility of bias among surgeons and nonsurgeons for treatment within their respective specialties. This study was conducted to determine who is contributing to the decision-making process in a multidisciplinary spine conference and to what extent treatment biases exist among the surgical and nonsurgical members of this conference. Voting data were collected during weekly multidisciplinary spine conferences. Descriptive statistics were calculated on the cases presented and the number and type of physicians voting for each case. The likelihood of a particular vote in the surgeon and nonsurgeon cohorts was evaluated using relative risk calculation and multinomial logistic regression. A total of 262 consecutive cases were analyzed. No significant differences in treatment recommendation were observed between surgery and nonsurgical management (relative risk, 1.1; 95% CI, 0.97-1.25) when comparing votes from the surgeon and nonsurgeon cohorts. Multinomial logistic regression showed the odds of nonsurgeons recommending nonsurgical management over surgery was 20% greater than receiving that recommendation from their surgeon colleagues. Individual surgeon and nonsurgeon voters were evenly distributed above and below the mean for treatment recommendation. Individual and group biases exist among surgeons and nonsurgeons treating degenerative spine diseases. Multidisciplinary conferences may or may not level these biases, depending on how they are conducted., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Study Design: Evaluation of new technology., Objectives: To evaluate the utility of a novel biomimetic spine model as a surgical planning and education resource in the treatment of cervical spine deformities (CSD)., Methods: Three patients with CSD were identified and synthetic spine models were manufactured to match the anatomical and biomechanical properties of each patient. Each model underwent 3 phases of surgical correction: maximum correction with no osteotomies performed, with posterior column osteotomies (PCOs) only, and with PCOs and a 3-column osteotomy (3CO). Lateral fluoroscopic films were obtained after each phase of correction for measurement of cervical lordosis. Surgeons were surveyed to obtain subjective feedback on the perceived model utility., Results: Each model began with a kyphotic deformity that was mobile, rigid, or fixed. The mobile model achieved successive lordotic correction with each phase of correction. The rigid and fixed models achieved much less correction with no osteotomies and PCOs only, and the majority of correction with 3COs. Each model predicted with varying, but overall high, accuracy the amount of correction achieved in each patient. The surgeons felt the model had very high utility as a surgical education platform., Conclusions: The models appeared to accurately replicate the gross anatomy and biomechanical performance of the patients' spines. This high fidelity to the individual patient's anatomy, bone quality, and segmental mobility resulted in a custom model that provides an invaluable learning platform for surgical education. These results suggest the models may have utility in surgical planning, but further studies are needed.

Background: The Living Spine Model (LSM) is a three-dimensionally printed, surgical training platform developed by neurosurgical residents., Objective: To evaluate the face and content validity of this model as a training tool for open posterior lumbar surgery., Methods: Six surgeons with varying experience were asked to complete L3-5 pedicle screw fixation and L3-4 laminectomy on an LSM. Face validity was measured using a questionnaire, and content validity was measured using the National Aeronautics and Space Administration Task Load Index (NASA TLX) tests. Student's t-test was used to compare NASA TLX responses between junior and senior residents and to compare responses for live surgery vs simulated surgery on the LSM., Results: Junior residents took the longest time to complete the procedure, followed by senior residents and the attending surgeon (136.5, 98.3, and 84 min, respectively). The junior residents placed fewer successful pedicle screws (7/12) than senior residents and attending surgeon (18/18). All tested components of the model had excellent face validity, with scores ranging from 60% to 97%. Content validity testing demonstrated that the LSMs created overall workloads and specific types of work like live operating conditions., Conclusion: The overall validity testing of the LSM demonstrates the high-potential utility of this model as a surgical education and testing platform for open posterior lumbar procedures. The LSM has great potential as an adjunct to surgical education, and it may become an increasingly important component of surgical resident curricula in the future., (Copyright © 2019 by the Congress of Neurological Surgeons.)

Study Design: Biomechanical model study., Objective: The Barrow Biomimetic Spine (BBS) project is a resident-driven effort to manufacture a synthetic spine model with high biomechanical fidelity to human tissue. The purpose of this study was to investigate the performance of the current generation of BBS models on biomechanical testing of range of motion (ROM) and axial compression and to compare the performance of these models to historical cadaveric data acquired using the same testing protocol., Methods: Six synthetic spine models comprising L3-5 segments were manufactured with variable soft-tissue densities and print orientations. Models underwent torque loading to a maximum of 7.5 N m. Torques were applied to the models in flexion-extension, lateral bending, axial rotation, and axial compression. Results were compared with historic cadaveric control data., Results: Each model demonstrated steadily decreasing ROM on flexion-extension testing with increasing density of the intervertebral discs and surrounding ligamentous structures. Vertically printed models demonstrated markedly less ROM than equivalent models printed horizontally at both L3-4 (5.0° vs 14.0°) and L4-5 (3.9° vs 15.2°). Models D and E demonstrated ROM values that bracketed the cadaveric controls at equivalent torque loads (7.5 N m)., Conclusions: This study identified relevant variables that affect synthetic spine model ROM and compressibility, confirmed that the models perform predictably with changes in these print variables, and identified a set of model parameters that result in a synthetic model with overall ROM that approximates that of a cadaveric model. Future studies can be undertaken to refine model performance and determine intermodel variability., Competing Interests: Declaration of Conflicting Interests: Author MAB is the inventor on a patent filing describing the technology evaluated in this study. This patent filing was licensed to a new company during the late stages of the peer-review process. Authors MAB, SM, and UKK have financial interests in the new company that licensed the patent., (© The Author(s) 2019.)

Atlantoaxial pseudoarthrosis is a challenging postoperative complication. The use of a local, vascularized bone graft, without free tissue transfer, to support a revision atlantoaxial fusion has not been previously described. We report the first surgical patient who received a semispinalis capitis muscle pedicled, occipital bone graft for supplementation of a revision atlantoaxial arthrodesis. A 72-year-old female had a failed atlantoaxial fusion and developed neck pain from continued instability and fractured hardware. The fixation and fusion were revised and supplemented with a novel, pedicled occipital bone graft. A craniectomy was performed in the occipital bone while still attached to the semispinalis capitis muscle to provide graft vascularity. This graft was rotated inferiorly from the skull base to the C1 arch and C2 spinous process in order to supplement a revision atlantoaxial arthrodesis. The patient had excellent clinical recovery over 18-month clinical follow up. The bone graft harvesting and rotation were performed safely and without complication. The 6-month postoperative CT scan showed partial fusion into the graft. This novel surgical technique leverages the advantages of vascularized structural autograft without adding extensive time or morbidity to the procedure as observed in free-tissue transfers. It is a safe and useful salvage technique to supplement revision atlantoaxial fusion surgeries., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Objective: In ventriculoperitoneal shunt (VPS) placement, distal placement of the peritoneal catheter will typically be performed by a neurosurgeon. More recently, laparoscopic-assisted (LA) placement of the distal peritoneal catheter by general surgeons has become common. The present study examined whether LA placement of a VPS (LAVPS) is associated with a reduced operative time, lower hospital costs, and fewer distal revisions., Methods: A retrospective review was performed of the data from all patients who had received a new VPS at our institution from 2013 to 2016. Age, sex, diagnosis, previous abdominal surgery, operative time, anesthesia grade, incidence of 30-day shunt failure, and total hospital charges were analyzed., Results: A total of 680 patients had undergone first-time VPS placement, including 199 with LAVPS and 481 with non-LAVPS placement (non-LAVPS). The mean age of the LAVPS patients was significantly older than that of the non-LAVPS patients (64.1 vs. 59.3 years; P = 0.002). The mean operative time was shorter in the LAVPS group than in the non-LAVPS group (55 vs. 75 minutes; P < 0.001). Distal shunt revision within 30 days occurred more often for the non-LAVPS patients (6 of 481 [1.2%]) than for the LAVPS patients (0 of 199 [0%]). A subset analysis of patients with normal-pressure hydrocephalus found decreased total hospital charges in the LAVPS group ($67,124 vs. $80,890; P = 0.009)., Conclusions: Compared with non-LAVPS, LAVPS was associated with significantly shorter operative times and fewer distal shunt revisions within 30 days. The findings from a subset analysis supported a decrease in total hospital charges. Additional studies are needed; however, these data suggest that LAVPS is a safer, less-expensive alternative to non-LAVPS., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: To measure the incidence and severity of cement extravasation in adult patients undergoing prophylactic vertebroplasty as part of a spinal reconstruction procedure., Methods: Consecutive adult patients treated with prophylactic vertebroplasty during a spinal reconstruction procedure were reviewed over a 46-month period. Patients without a postoperative computed tomography scan were excluded. Spine reconstruction was defined as any procedure involving ≥6 levels of fusion or a 3-column osteotomy. Cement extravasation was graded using a novel grading system. Fisher exact tests were performed to identify independent predictors of cement extravasation., Results: Inclusion and exclusion criteria were met by 34 patients comprising 112 vertebral bodies (VB). All 34 patients (100%) had computed tomography evidence of cement extravasation. Of 112 VBs, 103 (92.0%) demonstrated cement extravasation. Thirteen VBs (11.6%) in 9 patients (26.5%) had cement extending to the vena cava or end-organs or cement causing spinal canal stenosis (grade 4 and 5 extravasation). No permanent clinical sequelae were found in these 9 patients. Upper thoracic vertebrae (C7-T6) had significantly higher rates of grade 4 and 5 extravasation than lower thoracic-lumbar vertebrae (T7-L5) (P = 0.004)., Conclusions: Although no patients in this study experienced known long-term consequences of prophylactic vertebroplasty, 26.5% of patients had cement extravasation that threatened end-organs or neural elements. These results prompted us to change our practice from cementing upper thoracic VBs to using hooks instead. Cement injection is associated with serious risks and should be performed selectively. Larger prospective studies are needed to verify these results., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Three-dimensional (3D) printing holds great potential for lateral skull base surgical training; however, studies evaluating the use of 3D-printed models for simulating transtemporal approaches are lacking., Objective: To develop and evaluate a 3D-printed model that accurately represents the anatomic relationships, surgical corridor, and surgical working angles achieved with increasingly aggressive temporal bone resection in lateral skull base approaches., Methods: Cadaveric temporal bones underwent thin-slice computerized tomography, and key anatomic landmarks were segmented using 3D imaging software. Corresponding 3D-printed temporal bone models were created, and 4 stages of increasingly aggressive transtemporal approaches were performed (40 total approaches). The surgical exposure and working corridor were analyzed quantitatively, and measures of face validity, content validity, and construct validity in a cohort of 14 participants were assessed., Results: Stereotactic measurements of the surgical angle of approach to the mid-clivus, residual bone angle, and 3D-scanned infill volume demonstrated comparable changes in both the 3D temporal bone models and cadaveric specimens based on the increasing stages of transtemporal approaches (PANOVA <.003, <.007, and <.007, respectively), indicating accurate representation of the surgical corridor and working angles in the 3D-printed models. Participant assessment revealed high face validity, content validity, and construct validity., Conclusion: The 3D-printed temporal bone models highlighting key anatomic structures accurately simulated 4 sequential stages of transtemporal approaches with high face validity, content validity, and construct validity. This strategy may provide a useful educational resource for temporal bone anatomy and training in lateral skull base approaches., (Copyright © 2019 by the Congress of Neurological Surgeons.)

Background: Posterior column osteotomy (PCO) is a powerful technique for correcting lordosis, but the surgical literature lacks objective evidence on preoperative predictors of achievable lordotic correction following PCO., Objective: To measure the correlation between disc geometry and achievable lordotic correction following Schwab grade 2 osteotomies and to describe geometric changes to disc space following lordotic correction., Methods: Schwab grade 2 osteotomies were performed from T1 to S1 in 5 cadavers. Lateral radiographs were taken before and after posterior column compression. Anterior disc height (ADH), middle disc height (MDH), posterior disc height (PDH), and lordotic angles were measured. The association between disc height and lordotic correction was analyzed using linear regression., Results: For all spinal levels (n = 79), PDH was most strongly correlated with lordotic correction (r = 0.72, P < .001). Regional subset analyses showed the strongest correlation between PDH and lordotic correction achievable within the lumbar spine (n = 22, r = 0.77, P < .001), followed by ADH for lower thoracic spine (n = 29, r = 0.65, P < .001) and PDH for upper thoracic spine (n = 28, r = 0.61, P = .001). Postcorrection analysis of disc heights revealed that as lordotic correction increases, the PDH decreases, and the ADH expands., Conclusion: PDH is a strong predictor of achievable lordotic correction following Schwab grade 2 osteotomies and compression of an intact disc space. In the lumbar spine, 50% of lordotic change is predictable using PDH alone. Further testing of our linear regression equation is planned for prospective clinical studies, and further testing of postcorrection disc space geometry is planned for future biomechanical and surgical technique studies., (Copyright © 2018 by the Congress of Neurological Surgeons.)

Background: Previous studies have demonstrated that, by using various three-dimensional (3D) printing technologies, synthetic spine models can be manufactured to mimic a human spine in its gross and radiographic anatomy and the biomechanical performance of bony and ligamentous tissue. These manufacturing processes have not, however, been used in combination to create a long-segment, biomimetic model of a patient with scoliosis. The purpose of this study was to describe the development of a biomimetic scoliosis model and early clinical experience using this model as a surgical planning and education platform., Methods: Synthetic spine models were printed to mimic the anatomy and biomechanical performance of 2 adult patients with scoliosis. Preoperatively, the models were surgically corrected by the attending surgeon of each patient. Patients then underwent surgical correction of their spinal deformities. Correction of the models was compared to the surgical correction in the patients., Results: Patient 1 had a preoperative coronal Cobb angle of 40° from L1 to S1, as did the patient's synthetic spine model. The patient's spine model was corrected to 17.6°, and the patient achieved a correction of 17.3°. Patient 2 had a preoperative mid-thoracic Cobb angle of 88° and an upper thoracic Cobb angle of 43°. Preoperatively, the patient's spine model was corrected to 19.5° and 9.2° for the mid-thoracic and upper thoracic curves, respectively. Immediately after surgery, the patient's mid-thoracic and upper thoracic Cobb angles measured 18.7° and 9.5°, respectively. In both cases, the use of the spine models preoperatively changed the attending surgeon's operative plan., Conclusions: A novel synthetic spine model for corrective scoliosis procedures is presented, along with early clinical experience using this model as a surgical planning platform. This model has tremendous potential not only as a surgical planning platform but also as an adjunct to patient consent, surgical education, and biomechanical research., Competing Interests: Conflicts of Interest: MA Bohl is the inventor on a patent filing describing the technology evaluated in this study. The patent is owned by the institution where this work took place. This patent filing was licensed to a new company during the peer-review process. MA Bohl, S McBryan, and UK Kakarla have financial interests in the new company that licensed the patent. The other authors have no conflicts of interest to declare., (2019 Journal of Spine Surgery. All rights reserved.)

Study Design: Description and evaluation of a novel surgical training platform., Objectives: The purpose of this study was to investigate the face, content, and construct validity of 5 novel surgical training models that simulate freehand and percutaneous (minimally invasive surgery [MIS]) pedicle screw placement., Methods: Five spine models were developed by residents: 3 for freehand pedicle screw training (models A-C) and 2 for MIS pedicle screw training (models D and E). Attending spine surgeons evaluated each model and, using a 20-point Likert-type scale, answered survey questions on model face, content, and construct validity. Scores were statistically evaluated and compared using means, standard deviations, and analysis of variance between models and between surgeons., Results: Among the freehand models, model C demonstrated the highest overall validity, with mean face (15.67 ± 5.49), content (19.17 ± 0.59), and construct (18.83 ± 0.24) validity all measuring higher than the other freehand models. For the MIS models, model D had the highest validity scores (face, content, and construct validity of 11.67 ± 3.77, 18.17 ± 2.04, and 17.00 ± 3.46, respectively). The 3 freehand models differed significantly in content validity scores ( P = .002) as did the 2 MIS models ( P < .001). The testing surgeons' overall validity scores were significantly different for models A ( P = .005) and E ( P < .001)., Conclusions: A 3-dimensional-printed spine model with incorporated bone bleeding and silicone rubber soft tissue was scored as having very high content and construct validity for simulating freehand pedicle screw insertion. These data has informed the further development of several surgical training models that hold great potential as educational adjuncts in surgical training programs., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: Desmoid tumors are known to be rare and relatively slow growing with locally invasive histology and high recurrence rates. A rare subset of these tumors occurs adjacent to the spinal column after surgery. Since 1961, only 6 cases of postoperative paraspinal desmoid tumor have been reported. This report is the first to describe the occurrence of a paraspinal desmoid tumor after surgical correction of a spinal deformity., Case Description: A 56-year-old woman with multiple sclerosis reported 2-3 years of progressively worsening mid and low back pain that was worse with standing and ambulation and almost completely relieved with lying flat. Standing anteroposterior scoliosis radiographs revealed a thoracolumbar spinal deformity, which was surgically corrected with a T4 pelvis spinal fixation and fusion. At her 2-year postoperative clinic visit the patient reported good improvement in her preoperative symptoms but felt a fullness in her right upper back and neck that was nontender. Magnetic resonance imaging revealed a large tumor in this region. The tumor was resected en bloc, and pathology noted a 14.5 cm × 8.7 cm × 4.2 cm mass with spindle cell proliferation and positive staining for β-catenin (mutated gene found in 85% of desmoid tumors)., Conclusions: This is the first report of a postoperative desmoid tumor after spinal deformity correction and the seventh reported case in the spine literature. All reported cases have been women aged 39-57 years. The patient will be followed closely with magnetic resonance imaging given the known high local recurrence rate of this tumor., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: An increasing body of literature describing use of high-fidelity surgical training models is challenging long-held dogma that cadavers provide the best medium for postgraduate surgical skills training. The purpose of this study was to describe a surgical skills course comprising entirely synthetic training models developed by resident and attending neurosurgeons and to evaluate their perceptions of the overall usefulness of this course and its usefulness compared with cadaveric courses., Methods: Ten high-fidelity neurosurgical training models were developed. A neurosurgical skills course for residents was structured to include 7 spinal and 3 cranial learning stations, each with its own model and assigned attending expert. Resident and attending neurosurgeons were asked to complete surveys on their overall impressions of the course and models and on workload comparisons between models and real cases. Student t tests were used for statistical comparisons., Results: Survey responses were collected from 9 of 16 participating residents (56.3%) and 3 of 10 attending neurosurgeons (30.0%). Both groups believed that the course was very helpful overall to resident education. Respondents furthermore believed that the course was more helpful overall than cadaveric courses. Task load index testing showed no significant workload difference between models and real cases (P ≥ 0.17), except in temporal demand (P < 0.001)., Conclusions: Resident and attending neurosurgeons subjectively believe that high-fidelity synthetic models were superior to cadavers as a surgical skills teaching platform. This study raises the question of whether cadavers should remain the gold standard for surgical skills courses. Expanded use of these teaching models and further study are warranted., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Patient out-of-pocket (OOP) spending is an increasingly discussed topic; however, there is minimal data available on the patient financial burden of surgical procedures., Objective: To analyze hospital and surgeon expected payment data and patient OOP spending in neurosurgery., Methods: This is a retrospective cohort study of neurosurgical patients at a tertiary-referral center from 2013 to 2016. Expected payments, reflecting negotiated costs-of-care, as well as actual patient OOP payments for hospital care and surgeon professional fees were analyzed. A 4-tiered model of patient OOP cost sharing and a multivariate model of patient expected payments were created., Results: A total of 13 673 consecutive neurosurgical cases were analyzed. Patient age, insurance type, case category, severity of illness, length of stay (LOS), and elective case status were significant predictors of increased expected payments (P < .05). Craniotomy ($53 397 ± 811) and posterior spinal fusion ($48 329 ± 864) were associated with the highest expected payments. In a model of patient OOP cost sharing, nearly all neurosurgical procedures exceeded yearly OOP maximums for Healthcare Marketplace plans. Mean patient payments for hospital care and surgeon professional fees were the highest for anterior/lateral spinal fusion cases for commercially insured patients ($1662 ± 165). Mean expected payments and mean patient payments for commercially insured patients increased significantly from 2013 to 2016 (P < .05)., Conclusion: Expected payments and patient OOP spending for commercially insured patients significantly increased from 2013 to 2016, representing increased healthcare costs and patient cost sharing in an evolving healthcare environment. Patients and providers can consider this information prior to surgery to better anticipate the individual financial burden for neurosurgical care., (Copyright © 2018 by the Congress of Neurological Surgeons.)

Background: Optimal transfusion thresholds have been extensively studied for various surgical procedures; however, no transfusion threshold has been set for patients undergoing complex spine surgery. The aim of this study was to compare postoperative outcomes relative to perioperative hemoglobin (Hb) levels for patients undergoing complex spine surgery for adult spinal deformity and to evaluate impact of blood transfusion timing on clinical outcomes., Methods: Retrospective chart review of patients with adult spinal deformity undergoing spine surgery lasting >6 hours or involving ≥6 levels of fusion was performed. Patients were divided into 2 cohorts based on whole hospitalization Hb nadir <9.0 g/dL versus ≥9.0 g/dL., Results: Among 104 patients, 55 (52.9%) had Hb nadir <9.0 g/dL. Compared with the cohort with higher Hb nadir, patients with Hb nadir <9.0 g/dL were more likely to be female (84.5% vs. 65.3%, P = 0.016), present with lower preoperative Hb (12.6 [1.5] g/dL vs. 13.8 [1.2] g/dL, P < 0.001), experience greater change in Hb after surgery (4.4 [1.5] g/dL vs. 3.7 [1.5] g/dL, P = 0.030), receive a postoperative blood transfusion (69.1% vs. 44.9%, P = 0.013), and have a longer length of stay (9.1 [4.8] days vs. 6.2 [3.2] days, P < 0.001)., Conclusions: In patients with adult spinal deformity undergoing complex spine surgery, earlier targeted blood transfusions during surgery, rather than in the postoperative period, may lead to improved postoperative outcomes., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background Context: Lumbosacral pseudoarthrosis and instrumentation failure is common with long-segment constructs. Optimizing lumbosacral construct biomechanics may help to reduce failure rates. The influence of iliac screws and interbody type on range of motion (ROM), rod strain (RS), sacral screw strain (SS) is not well-established., Purpose: Investigate the effects of transforaminal lumbar interbody fusion (TLIF), anterior lumbar interbody fusion (ALIF), and iliac screws on long-segment lumbosacral construct biomechanics., Study Design: Biomechanical study., Patient Sample: Fourteen human cadaveric spine specimens., Outcome Measures: Lumbosacral ROM, RS, and SS., Methods: Specimens were potted at L1 and the ilium. Specimens were equally divided into either an L5-S1 ALIF or TLIF group and underwent testing in the following conditions: (1) intact (2) L2-S1 pedicle screw rod fixation (PSR-S) (3) L2-ilium (PSR-I) (4) PSR-S+ALIF (ALIF-S) or TLIF (TLIF-S) (5) PSR-I + ALIF (ALIF-I) or TLIF (TLIF-I). Pure moment bending (7.5 Nm) in flexion, extension, lateral bending, axial rotation, and compressive loads (400N) were applied and ROM, SS, and RS were measured. Comparisons were performed using a one-way ANOVA (p<.05)., Results: ALIF-S and TLIF-S provided similar decreases in ROM as TLIF-I (p>.05). Compared to PSR-S, PSR-I significantly decreased SS during bending in all directions (p<.02) but increased RS in flexion and extension (p≤.02). Anterior lumbar interbody fusion-S provided similar decreases in SS as TLIF-I in all directions (p>.40) but had significantly less RS than TLIF-I in flexion, extension, compression (p<.01). TLIF-S had more SS than TLIF-I in flexion, extension, axial rotation (p<.02), while TLIF-S had less RS only in flexion (p=.03). Compared to PSR-I, ALIF-I decreased the RS (p<.02) but TLIF-I did not (p>.67)., Conclusions: Iliac screws were protective of SS but increased RS at the lumbosacral junction. Constructs with ALIF and no iliac screws result in comparable SS as constructs with TLIF and iliac screws with significantly reduced RS. If iliac screws are utilized, ALIF but not TLIF reduces the iliac screw-induced RS., Clinical Significance: There is a relatively high incidence of lumbosacral instrumentation failure in adult spinal deformity. Optimizing lumbosacral construct biomechanics may help to reduce failure rates. Iliac screws induce lumbosacral rod strain and may be responsible for instrumentation failure. Constructs with lumbosacral ALIF reduce iliac-screw induced rod strain and may obviate the need for fixation to the ilium., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: Rotational vascularized autografts are ideal for achieving spinal arthrodesis because they maintain bony vascularization while avoiding the morbidity and challenges of free-tissue transfer. Although proximal ribs are ideal candidates for vascularized bone grafts, their use is restricted to the thoracic spine. This study describes a novel technique for harvesting lateral rib grafts on an intercostal pedicle for use in cervical and lumbar posterolateral arthrodesis., Methods: Six cadaveric dissections were performed (2 included upper and all 6 included lower rib dissections). Measurements included graft width and thickness, distance reached from harvest level to the top of the graft, and ipsilateral and contralateral spine levels reached by the graft., Results: Overall, 60 lateral rib grafts were harvested. Intercostal vessel pedicles were torn during harvest in 4/48 (8.3%) of the lower rib and 5/12 (41.7%) of the upper rib grafts. Mean measurements of successful upper rib grafts were 1.4 ± 0.12 cm × 0.5 ± 0.15 cm (width × thickness), 14.1 ± 2.79 cm (distance) reached, and C2 (occiput-C4) reached ipsilaterally and C3 (occiput-C5) reached contralaterally. Mean lower rib graft measurements were 1.4 ± 0.26 cm × 0.4 ± 0.15 cm (width × thickness), 18.0 ± 6.19 cm (distance), S1 (L1-S2) reached ipsilaterally, and L4 (L1-S1) reached contralaterally., Conclusions: It is technically feasible to rotate a far-lateral rib graft on an intercostal pedicle into the posterolateral cervical or lumbar spine for the augmentation of arthrodesis. Upper ribs seem to be more difficult to harvest and rotate while keeping the intercostal pedicle intact than lower ribs.

Anterior column release is a powerful surgical technique for achieving spinopelvic balance in adult patients with sagittal plane deformities. We present an alternative strategy for focal deformity correction from a posterior-only approach. The purpose of this study was to evaluate the feasibility and efficacy of a novel surgical technique called posterior open-wedge diskectomy and anterior longitudinal ligament (ALL) release (POWAR). A cadaveric torso underwent POWARs at the L1-L4 intervertebral disc spaces. Baseline measurements of end-plate angle (EPA), anterior intervertebral disc height (ADH), and posterior intervertebral disc height (PDH) were obtained. These measurements were repeated after three stages of correction: posterior column compression alone, posterior column compression following Schwab grade 2 osteotomies, and posterior column compression following POWAR. A second cadaver underwent posterolateral spinal dissection to demonstrate the pertinent anatomical features relevant to this novel procedure. With each stage of correction, a sequential increase in EPA and ADH and a decrease in PDH were demonstrated. The large increase in ADH seen following POWAR confirmed successful release of the ALL. In situ investigation of the aorta and inferior vena cava following anterior exposure revealed no injury to the great vessels or surrounding structures. Ex vivo testing of the aorta and inferior vena cava took place at the L3-4 level. This testing demonstrated no injury or tears to either vessel. POWAR is a new surgical technique that can provide an alternative to three-column osteotomy for surgeons performing spinal reconstructions in adults through an open, posterior-only approach. Clin. Anat. 32:348-353, 2019. © 2018 Wiley Periodicals, Inc., (© 2018 Wiley Periodicals, Inc.)

Background: The Schwab osteotomy grading scale-a unified osteotomy classification system created in 2014 by Schwab et al .-is one of many concepts in spine surgery that require detailed knowledge of 3-dimensional (3D) anatomy. 3D-printed spine models have demonstrated increasing utility in spine surgery as they more quickly communicate information on complex 3D anatomical relationships than planar imaging or 2-dimensional images. The purpose of this study was to evaluate the utility of a custom, 3D-printed spine model to help surgical trainees understand and perform the Schwab osteotomy grading scale., Methods: Eight participants were randomized into 2 groups: group 1 received written instructional materials about the Schwab osteotomy grading scale, whereas group 2 received both written materials and a 3D-printed model of the spine with osteotomy regions demarcated. All participants were administered written and practical examinations., Results: The group randomized to receive the 3D-printed model performed significantly better on both the written assessment (mean score, 7.75±0.50 vs . 5.75±0.50, P=0.023) and the practical examination (mean score, 1.75±0.32 vs . 1.08±0.09, P=0.025) than the group that received only written instructions., Conclusions: Our results support the conclusion that this 3D-printed spine model is an effective adjunct to help early surgical trainees understand the Schwab osteotomy grading scale. Participants who received the model in addition to the source manuscript demonstrated improved theoretical knowledge and better performance on practical tests of complex spinal osteotomies. Similar models are likely to have utility in surgical training programs and as patient education models., Competing Interests: Conflicts of Interest: The authors have no conflicts of interest to declare.

Objective: Patients with hydrocephalus secondary to third ventricular colloid cysts can require bilateral external ventricular drain (EVD) placement while awaiting surgery. However, some patients could develop auto-fenestration of the septum pellucidum (AFSP) and only require 1 EVD. We evaluated our experience with bedside iohexol ventriculography and staged EVD placement for patients with obstructive hydrocephalus., Methods: We retrospectively identified 34 patients who had been treated for third ventricular colloid cysts (2013-2016). The preoperative and postoperative data, including age, sex, colloid cyst size, preoperative hydrocephalus, preoperative EVD placement, preoperative iohexol ventriculography, operative approach, intraoperative findings, and postoperative ventriculoperitoneal shunt requirements, were reviewed., Results: Hydrocephalus was found in 23 patients (68%) on initial presentation. Nine patients (26%) had EVDs placed before surgery. Six patients (18%) underwent iohexol ventriculography after insertion of a right-sided EVD. Five patients (15%) demonstrated no evidence of ventricular communication. Four patients (67%) required left-sided EVD placement. One patient (17%) had robust communication between the lateral ventricles after intraventricular iohexol injection, which was managed with a single EVD. AFSP was observed during surgical resection of this patient's colloid cyst. One other patient who did not undergo preoperative EVD placement was noted to have AFSP intraoperatively, resulting in 2 of 34 patients (6%) with AFSP in our series., Conclusions: A subset of patients with obstruction at the foramina of Monro can develop AFSP. Iohexol ventriculography after unilateral EVD placement allows clinicians to assess for the presence of AFSP and identify patients who can be treated with a single EVD before surgery., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background We examined the biomechanical performance of a three-dimensional (3D)-printed vertebra on pedicle screw insertional torque (IT), axial pullout (APO), and stiffness (ST) testing. Materials and methods Seventy-three anatomically identical L5 vertebral body models (146 pedicles) were printed and tested for IT, APO, and ST using single-threaded pedicle screws of equivalent diameter (6.5 mm), length (40.0 mm), and thread pitch (2.6 mm). Print properties (material, cortical thickness [number of shells], cancellous density [in-fill], in-fill pattern, print orientation) varied among models. One-way analysis of variance was performed to evaluate the effects of variables on outcomes. Results The type of material significantly affected IT, APO, and ST (P < 0.001, all comparisons). For acrylonitrile butadiene styrene (ABS) models, in-fill density (25-35%) had a positive linear association with APO (P = 0.002), ST (P = 0.008), and IT (P = 0.10); similarly for the polylactic acid (PLA) models, APO (P = 0.001), IT (P < 0.001), and ST (P = 0.14). For the nylon material type, in-fill density did not affect any tested parameter. For a given in-fill density, material, and print orientation, the in-fill pattern significantly affected IT (P = 0.002) and APO (P = 0.03) but not ST (P = 0.23). Print orientation also significantly affected IT (P < 0.001), APO (P < 0.001), and ST (P = 0.002). Conclusions 3D-printed vertebral body models with specific print parameters can be designed to perform analogously to human bone on pedicle screw tests of IT, APO, and ST. Altering the material, in-fill density, in-fill pattern, and print orientation of synthetic vertebral body models could reliably produce a model that mimics bone of a specific bone mineral density., Competing Interests: The authors have declared that no competing interests exist.

Background: Many surgeons utilize assistants to perform procedures in more than one operating room at a given time using a practice known as overlapping surgery. Debate has continued as to whether overlapping surgery improves the efficiency and access to care or risks patient safety and outcomes., Objective: To examine effects of overlapping surgery in deep brain stimulation (DBS) for movement disorders., Methods: In this retrospective analysis of overlapping and non-overlapping cases, we evaluated stereotactic accuracy, operative duration, length of hospital stay, and the presence of hemorrhage, wound-related complications, and hardware-related complications requiring revision in adults with movement disorders undergoing DBS., Results: Of 324 cases, 141 (43.5%) were overlapping and 183 (56.5%) non-overlapping. Stereotactic error, number of brain penetrations, and postoperative length of hospitalization did not differ significantly (p ≥ 0.08) between the overlapping and non-overlapping groups. Mean operative duration was significantly longer for overlapping (81/141 [57.4%], 189.5 ± 10.8 min) than for non-overlapping cases (79/183 [43.2%], 169.9 ± 7.6 min; p = 0.004). There were no differences in rates of wound-related complications or hemorrhages, but overlapping cases had a significantly higher rate of hardware-related complications requiring revision (7/141 [5.0%] vs. 0/183 [0%]; p = 0.002)., Conclusions: Overlapping and non-overlapping cases had comparable DBS lead placement accuracy. Overlapping cases had a longer operative duration and had a higher rate of hardware-related complications requiring revision., (© 2019 S. Karger AG, Basel.)