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Study Design: Retrospective cohort., Objective: Billing and coding-related administrative tasks are a major source of healthcare expenditure in the United States. We aim to show that a second-iteration Natural Language Processing (NLP) machine learning algorithm, XLNet, can automate the generation of CPT codes from operative notes in ACDF, PCDF, and CDA procedures., Methods: We collected 922 operative notes from patients who underwent ACDF, PCDF, or CDA from 2015 to 2020 and included CPT codes generated by the billing code department. We trained XLNet, a generalized autoregressive pretraining method, on this dataset and tested its performance by calculating AUROC and AUPRC., Results: The performance of the model approached human accuracy. Trial 1 (ACDF) achieved an AUROC of .82 (range: .48-.93), an AUPRC of .81 (range: .45-.97), and class-by-class accuracy of 77% (range: 34%-91%); trial 2 (PCDF) achieved an AUROC of .83 (.44-.94), an AUPRC of .70 (.45-.96), and class-by-class accuracy of 71% (42%-93%); trial 3 (ACDF and CDA) achieved an AUROC of .95 (.68-.99), an AUPRC of .91 (.56-.98), and class-by-class accuracy of 87% (63%-99%); trial 4 (ACDF, PCDF, CDA) achieved an AUROC of .95 (.76-.99), an AUPRC of .84 (.49-.99), and class-by-class accuracy of 88% (70%-99%)., Conclusions: We show that the XLNet model can be successfully applied to orthopedic surgeon's operative notes to generate CPT billing codes. As NLP models as a whole continue to improve, billing can be greatly augmented with artificial intelligence assisted generation of CPT billing codes which will help minimize error and promote standardization in the process., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: JK, Stryker: Paid consultant, SK, FAAOS; AAOS: Board or committee member; American Orthopaedic Association: Board or committee member; AOSpine North America: Board or committee member; Cervical Spine Research Society: Board or committee member; Globus Medical: IP royalties; North American Spine Society: Board or committee member; Scoliosis Research Society: Board or committee member; Stryker: Paid consultant; KR, FAAOS; America: Stock or stock Options; AOSpine: Board or committee member; AxioMed: Stock or stock Options; Benvenue: Stock or stock Options; Biomet: IP royalties; Paid presenter or speaker; Clinics in orthopedics: Editorial or governing board; European Spine Journal: Editorial or governing board; Expanding Orthopedics, PSD: Stock or stock options; Global Spine Journal: Editorial or governing board; HAPPE Spine: Unpaid consultant; Medtronic: Paid presenter or speaker; Neurosurgery: Editorial or governing board; North American Spine Society: Board or committee member; Nuvasive: Paid consultant; Paid presenter or speaker; Paradigm Spine: Stock or stock Options; Spinal Kinetics: Stock or stock Options; Spine: Editorial or governing board; Spine Surgery Today: Editorial or governing board; Spineology: Stock or stock Options; Vertiflex: Stock or stock Options. The following individuals have no conflicts of interest or sources of support that require acknowledgement: BZ, JT, VA, BC, AD, EG, CD.

Study Design: Systematic review., Objectives: Lumbar degenerative disc disease (DDD) poses a significant global health care challenge, with accurate diagnosis being difficult using conventional methods. Artificial intelligence (AI), particularly machine learning and deep learning, offers promising tools for improving diagnostic accuracy and workflow in lumbar DDD. This study aims to review AI-assisted magnetic resonance imaging (MRI) diagnosis in lumbar DDD and discuss current research for clinical use., Methods: A systematic search of electronic databases identified studies on AI applications in MRI-based lumbar DDD diagnosis, following Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Search terms included combinations of "Artificial Intelligence," "Machine Learning," "Deep Learning," "Low Back Pain," "Lumbar," "Disc," "Degeneration," and "MRI," targeting studies in English from January 1, 2010, to January 1, 2024. Inclusion criteria encompassed experimental and observational studies in peer-reviewed journals. Data extraction focused on study characteristics, AI techniques, performance metrics, and diagnostic outcomes, with quality assessed using predefined criteria., Results: Twenty studies met the inclusion criteria, employing various AI methodologies, including machine learning and deep learning, to diagnose lumbar DDD manifestations such as disc degeneration, herniation, and bulging. AI models consistently outperformed conventional methods in accuracy, sensitivity, and specificity, with performance metrics ranging from 71.5% to 99% across different diagnostic objectives., Conclusion: The algorithm model provides a structured framework for integrating AI into routine clinical practice, enhancing diagnostic precision and patient outcomes in lumbar DDD management. Further research and validation are needed to refine AI algorithms for real-world application in lumbar DDD diagnosis., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Randomized Clinical Trial., Objective: To compare the clinical efficacy and restoration of working capacity after MI (minimally invasive)-TLIF and O (open)-TLIF in railway workers with lumbar degenerative disease., Methods: 83 patients, who were indicated for two-level lumbar decompression and fusion were randomly assigned to one of two groups: group 1 (n = 44) had MI-TLIF procedure and group 2 (n = 39) had O-TLIF procedure. The functional status was assessed using SF-36, ODI and VAS for back and leg pain, preoperatively, at discharge, and at 3, 6, and 12 months postoperatively. MRI and CT were obtained 1-year follow-up. The percentage of patients who returned to work at 1-year, work intensity and the time to return to work post-operatively were analyzed., Results: At 1-year follow-up, the MI-TLIF group had significantly better ODI, VAS and SF-36 scores compared to the O-TLIF group. The postoperative MRIs revealed a statistically significantly less multifidus muscle atrophy in the MI group compared to the Open group. At 1-year follow-up, a comparable fusion ratio between MI group and Open group was recorded. After MI-TLIF procedure, depending on the workload, patients had a statistically significantly earlier return to work ( P < .05) and statistically significantly higher return to work rate compared with the O-TLIF group ( P < .05)., Conclusions: The use of two-level MI-TLIF in railway workers has made it possible to significantly improve long-term clinical results, reduce the risk of surgical complications, muscle atrophy and time to return to work compared to O-TLIF., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Guideline., Objectives: To develop an international guideline (AOGO) about the use of osteobiologics in anterior cervical discectomy and fusion (ACDF) for treating degenerative spine conditions., Methods: The guideline development process was guided by AO Spine Knowledge Forum Degenerative (KF Degen) and followed the Guideline International Network McMaster Guideline Development Checklist. The process involved 73 participants with expertise in degenerative spine diseases and surgery from 22 countries. Fifteen systematic reviews were conducted addressing respective key topics and evidence was collected. The methodologist compiled the evidence into GRADE Evidence-to-Decision frameworks. Guideline panel members judged the outcomes and other criteria and made the final recommendations through consensus., Results: Five conditional recommendations were created. A conditional recommendation is about the use of allograft, autograft or a cage with an osteobiologic in primary ACDF surgery. Other conditional recommendations are about the use of osteobiologic for single- or multi-level ACDF, and for hybrid construct surgery. It is suggested that surgeons use other osteobiologics rather than human bone morphogenetic protein-2 (BMP-2) in common clinical situations. Surgeons are recommended to choose 1 graft over another or 1 osteobiologic over another primarily based on clinical situation, and the costs and availability of the materials., Conclusion: This AOGO guideline is the first to provide recommendations for the use of osteobiologics in ACDF. Despite the comprehensive searches for evidence, there were few studies completed with small sample sizes and primarily as case series with inherent risks of bias. Therefore, high-quality clinical evidence is demanded to improve the guideline., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Cadaveric specimens., Objective: To perform a pathomorphological analysis of the degree of facet joint (FJ) degeneration utilizing fresh cadaveric models and correlating these structural changes with imaging findings., Methods: L1-L5 FSU including all tissue between the anterior longitudinal ligament to the posterior spinal structures were obtained on 28 patients at a mean of 5.7 hours post-mortem. The samples were fixed in an agar medium and CT and MRI were performed. The level of FJ degeneration was identified based on prior classifications Osteoarthritis Research Society International (OARSI), as was the facet angle and tropism. Pathomorphological assessment including articular cartilage cell density was performed according to prior established methodology., Results: Radiographically, a direct association was identified between FJ degeneration and patient age. Facet angle and tropism did not significantly vary by patient age. Pathomorphologically, there was a decrease in the cellular density of articular cartilage with increasing patient age. Similarly, there was a significant direct correlation between radiographic degree of degenerative changes in FJs with the age of cadavers and the degree of degeneration of FJs according to the morphological classification of OARSI, as well as a significant inverse correlation with cell density., Conclusion: A comprehensive assessment of various signs of FJ degeneration using cadaveric material has established that, based on radiographic imaging, it is possible to assess the microstructural state of FJ, including at an early stage of the disease. This data may be useful for surgeons in guiding therapeutic strategies based on individual biometric parameters of the FJ., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Retrospective, cohort study., Objectives: Hand function can be difficult to objectively assess perioperatively. In patients undergoing cervical spine surgery by a single-surgeon, we sought to: (1) use a hand dynamometer to report pre/postoperative grip strength, (2) distinguish grip strength changes in patients with radiculopathy-only vs myelopathy, and (3) assess predictors of grip strength improvement., Methods: Demographic and operative data were collected for patients who underwent surgery 2015-2018. Hand dynamometer readings were pre/postoperatively at three follow-up time periods (0-3 m, 3-6 m, 6-12 m)., Results: 262 patients (mean age of 59 ± 14 years; 37% female) underwent the following operations: ACDF (80%), corpectomy (25%), laminoplasty (19%), and posterior cervical fusion (7%), with 81 (31%) patients undergoing multiple operations in a single anesthetic setting. Radiculopathy-only was seen in 128 (49%) patients, and myelopathy was seen 134 (51%) patients. 110 (42%) had improved grip strength by ≥10-lbs, including 69/128 (54%) in the radiculopathy-only group, and 41/134 (31%) in the myelopathy group. Those most likely to improve grip strength were patients undergoing ACDF (OR 2.53, P = .005). Patients less likely to improve grip strength were older (OR = .97, P = .003) and underwent laminoplasty (OR = .44, 95% CI .23, .85, P = .014). Patients undergoing surgery at the C2/3-C5/6 levels and C6/7-T1/2 levels both experienced improvement during the 0-3-month time range (C2-5: P = .035, C6-T2: P = .015), but only lower cervical patients experienced improvement in the 3-6-month interval ( P = .030)., Conclusions: Grip strength significantly improved in 42% of patients. Patients with radiculopathy were more likely to improve than those with myelopathy. Patients undergoing surgery from the C2/3-C5/6 levels and the C6/7-T1/2 levels both significantly improved grip strength at 3-month postoperatively., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Study Design: Cross-sectional, international survey., Objectives: To evaluate the knowledge of spine surgeons regarding the use of electromyography (EMG) and nerve conduction studies (NCS) for degenerative cervical spine conditions (DCC)., Methods: All members of AO Spine International were emailed an anonymous survey to evaluate their clinical knowledge about the use of EMG and nerve conduction studies for DCC. Descriptive statistics were used to analyze the results, as well as to compare the answers among different groups of surgeons and assess demographic characteristics., Results: A total of 402 participants answered the survey, 91.79% were men from the 5 continents. There were 221 orthopedic surgeons (55.39%) and 171 neurosurgeons (42.86%), more than a half of them with a complete spinal fellowship (56.44%). The most common reasons that surgeons obtain the test is to differentiate a radiculopathy from a peripheral nerve compression (88.06%). As a group, the responding surgeons' knowledge regarding EMG-NCS was poor. Only 53.46% of surgeons correctly answered that EMG-NCS is unable to differentiate a C5 from a C6 radiculopathy. Only 23.47% of the surgeons knew that EMG-NCS are not able to diagnose a pre vs a post-fixed brachial plexus. Only 25% of the surgeons correctly answered a question regarding the test's ability to diagnose other neurological diseases., Conclusions: We found that our respondents' knowledge regarding EMG-NCS for DCC was poor. Identifying the weak points of knowledge about EMG-NCS may help to educate surgeons on the indications for the test and the proper way to interpret the results.

Study Design: Retrospective Cohort Study., Objectives: Using natural language processing (NLP) in combination with machine learning on standard operative notes may allow for efficient billing, maximization of collections, and minimization of coder error. This study was conducted as a pilot study to determine if a machine learning algorithm can accurately identify billing Current Procedural Terminology (CPT) codes on patient operative notes., Methods: This was a retrospective analysis of operative notes from patients who underwent elective spine surgery by a single senior surgeon from 9/2015 to 1/2020. Algorithm performance was measured by performing receiver operating characteristic (ROC) analysis, calculating the area under the ROC curve (AUC) and the area under the precision-recall curve (AUPRC). A deep learning NLP algorithm and a Random Forest algorithm were both trained and tested on operative notes to predict CPT codes. CPT codes generated by the billing department were compared to those generated by our model., Results: The random forest machine learning model had an AUC of .94 and an AUPRC of .85. The deep learning model had a final AUC of .72 and an AUPRC of .44. The random forest model had a weighted average, class-by-class accuracy of 87%. The LSTM deep learning model had a weighted average, class-by-class accuracy 0f 59%., Conclusions: Combining natural language processing with machine learning is a valid approach for automatic generation of CPT billing codes. The random forest machine learning model outperformed the LSTM deep learning model in this case. These models can be used by orthopedic or neurosurgery departments to allow for efficient billing.

Study Design: A retrospective radiologic study., Objective: The inflection point is the disc space between a lordotic and kyphotic segment of spine. To our knowledge, there has been no study evaluating changes in functional sagittal alignment determined by inflection points after cervical fusion surgery. The purpose is to identify changes in functional sagittal alignment after cervical fusion as determined by functional segments between cervicothoracic and thoracolumbar inflection points., Methods: Standing radiographs of the sagittal whole spine were taken in 62 patients who underwent cervical fusion procedures. We identified cervicothoracic and thoracolumbar inflection points in the sagittal plane and measured Cobb angles of resulting "functional" cervical, thoracic, and lumbar segments. We also measured the C2 and T1 sagittal vertical axis (SVA) distance to S1 and the anatomic cervical lordosis, thoracic kyphosis, lumbar lordosis, spinopelvic parameters, and T1 sagittal slope. We compared the pre- and post-op values., Results: The functional cervical segment and T1 sagittal slope increased postoperatively. C2 and T1 SVA distance to S1 decreased postoperatively. In patients with a single level fusion or lower instrumented vertebra (LIV) proximal or equal to C6, functional cervical segment, and anatomic cervical lordosis increased postoperatively. In those with multiple level fusion or LIV distal or equal to C7, the C2 SVA distance to S1 decreased postoperatively., Conclusions: After cervical fusion surgery, functional cervical sagittal parameters determined by the inflection point improve without changes in the anatomic sagittal parameters. Postoperative changes in functional sagittal parameters were affected by the number of fused levels and LIV.

Study Design: Retrospective cohort., Objective: Provide a comparison of surgical approach in the treatment of degenerative cervical myelopathy in patients with OPLL., Methods: A national database was queried to identify adult (≥18 years) patients with OPLL, who underwent at least a 2-level cervical decompression and fusion for cervical myelopathy from 2012-2014. A propensity-score-matching algorithm was employed to compare outcomes by surgical approach., Results: After propensity-score matching, 627 patients remained. An anterior approach was found to be an independent predictor for higher inpatient surgical complications(OR 5.9), which included dysphagia:14%[anterior]vs.1.1%[posterior] P -value < 0.001, wound hematoma:1.7%[anterior]vs.0%[posterior] P -value = 0.02, and dural tear:9.4%[anterior]vs.3.2%[posterior] P -value = 0.001. A posterior approach was an predictor for longer hospital length of stay by nearly 3 days(OR 3.4; 6.8 days[posterior]vs.4.0 days[anterior] P -value < 0.001). The reasons for readmission/reoperation did not vary by approach for 2-3-level fusions; however, for >3-level fusions, patients with an anterior approach more often had respiratory complications requiring mechanical ventilation( P -value = 0.038) and required revision fusion surgery( P -value = 0.015)., Conclusions: The national estimates for inpatient complications(25%), readmissions(9.9%), and reoperations(3.5%) are substantial after the surgical treatment of multi-level OPLL. An anterior approach resulted in significantly higher inpatient surgical complications, but this did not result in a longer hospital length of stay and the overall 90-day complication rates requiring readmission or reoperation was similar to those seen after a posterior approach. For patients requiring >3-level fusion, an anterior approach is associated with significantly higher risk for respiratory complications requiring mechanical ventilation and revision fusion surgery. Precise neurological complications and functional outcomes were not included in this database, and should be further assessed in future studies.

Study Design: Prospective non-randomized single-center cohort study., Objectives: To analyze the quality of postoperative magnetic resonance imaging of 2 structurally different cervical disc arthroplasty devices at the index and adjacent levels., Methods: A non-randomized, comparative, prospective, single-center study included 40 patients (23 men and 17 women) aged 32 (26-40) years. Two study groups were utilized: in the first (n = 20), a titanium prosthesis was used; in the second (n = 20), a cobalt-chromium implant was used. Evaluation of MRI studies before and after surgery was performed using sagittal and axial T2 weighted images by 2 specialists who were blinded to the prosthesis that was used. To determine the quality of an MRI image, the classification of Jarvik 2000, the radiological and orthopedic scales for assessing artifacts were used., Results: There was good-to-excellent inter-observer agreement for all of the MR parameters used for the titanium and satisfactory-to-good for the cobalt chromium group. The analysis of the quality of postoperative imaging using the Jarvik 2000 scale showed a statistically significant deterioration in MR images in the cobalt chromium group ( P < 0.001), compared to the titanium ( P = 0.091). Following a single-level total arthroplasty, the titanium group had better MRI images according to radiological and orthopedic scales ( P < 0.001)., Conclusion: Titanium cervical disc arthroplasty devices result in superior postoperative MR imaging, as compared to cobalt chromium prostheses, as the latter significantly reduces image quality due to the pronounced ferromagnetic effect.

Study Design: Retrospective case control., Objectives: The purpose of this study is to compare clinical outcomes and rates of symptomatic caudal adjacent segment pathology (ASP) in posterior cervical fusions (PCF) constructs with end-instrumented vertebrae in the cervical spine (EIV-C) to PCF constructs that end in the proximal thoracic spine (EIV-T)., Methods: Retrospective review of 1714 consecutive cervical spinal fusion cases was done. Two groups were identified: 36 cervical end-instrumented vertebra patients (age56 ± 10 yrs) and 53 thoracic EIV patients (age 57 ± 9 yrs). Symptomatic ASP was defined as revision surgery or nerve root injection (or recommended surgery or injection) at the adjacent levels., Results: EIV-C patients had a significantly higher rate of caudal-level symptomatic ASP requiring intervention compared with EIV-T patients (39% vs 15%, p = 0.01). The development of caudal-level ASP was highest at C7 (41%), followed by C6 (40%). The overall complication rate and surgical revision rates, however, were similar between the groups. Neck Disability Index outcomes at 2 years postop were significantly better in the EIV-T group (24.5 vs. 34.0, p = 0.05)., Conclusions: Long PCF that cross the C-T junction have superior clinical outcomes and reduced rates of caudal breakdown, at the expense of longer fusions and higher EBL, with no increase in the rate of complications. Crossing the C-T junction affords protection of the caudal adjacent levels without adding significant operative time or morbidity.

Study Design: Retrospective cohort study., Objective: Respiratory compromise (RC) is a rare but catastrophic complication of anterior cervical spine surgery (ACSS) commonly due to compressive fluid collections or generalized soft tissue swelling in the cervical spine. Established risk factors include operative duration, size of surgical exposure, myelopathy, among others. The purpose of this current study is to identify the incidence and clinical course of patients who develop RC, and identify independent predictors of RC in patients undergoing ACSS for cervical spondylosis., Methods: A large, prospectively-collected registry was used to identify patients undergoing ACSS for spondylosis. Patients with posterior cervical procedures were excluded. Baseline patient characteristics were compared using bivariate analysis, and multivariate analysis was employed to compare postoperative complications and identify independent predictors of RC., Results: 298 of 52,270 patients developed RC (incidence 0.57%). Patients who developed RC had high rates of 30-day mortality (11.7%) and morbidity (75.8%), with unplanned reoperation and pneumonia the most common. The most common reason for reoperations were hematoma evacuation and tracheostomy. Independent patient-specific factors predictive of RC included increasing patient age, male gender, comorbidities such as chronic cardiac and respiratory disease, preoperative myelopathy, prolonged operative duration, and 2-level ACCFs., Conclusion: This is among the largest cohorts of patients to develop RC after ACSS identified to-date and validates a range of independent predictors, many previously only described in case reports. These results are useful for taking preventive measures, identifying high risk patients for preoperative risk stratification, and for surgical co-management discussions with the anesthesiology team.

Study Design: Retrospective study., Objective: To examine the associated indications, procedures, and postoperative outcomes after revision ACDA., Methods: We utilized a national database to identify adult(≥18 years) patients who underwent either a primary ACDA or removal of ACDA over a 10-year period(2008-2017). An in-depth assessment of the reasons for revision surgery and the subsequent procedures performed after the removal of ACDA was done by using both Current Procedural Terminology(CPT) and International Statistical Classification of Diseases (ICD-9,10) coding., Results: From 2008 to 2017, a total of 3,350 elective, primary ACDA cases were performed. During this time, 69 patients had a revision surgery requiring the removal of ACDA. The most common reasons for revision surgery included cervical spondylosis(59.4%) and mechanical complications(27.5%). After removal of ACDA, common procedures performed included anterior cervical fusion with or without decompression(69.6%), combined anterior/posterior fusion/decompression (11.6%), and replacement of ACDA (7.2%). The indications for surgery did not vary significantly among the different procedures performed (p = 0.318). Patients requiring revision surgery for mechanical complications or those who underwent a combined surgical approach were at significantly higher risk for subsequent short-term complications (p<0.05)., Conclusion: Over a 10-year period, the rate of revision surgery for ACDA was low (2.1%). Nearly 90% of revision cases were due to either cervical spondylosis or mechanical complications. These indications for surgery did not vary significantly among the different procedures performed. These findings will be important during the shared-decision making process for patients undergoing primary or revision ACDA.

Study Design: Retrospective Cohort., Objective: To compare the short-term outcomes for Laminoplasty, Laminectomy/fusion, and ACDF., Methods: We utilized a prospectively-collected, multi-center national database with a propensity score matching algorithm to compare the short-term outcomes for laminoplasty, laminectomy/fusion, and multi-level ( > 3) ACDF (with and without corpectomy). Bivariate analyses involved both chi-square/fisher exact test and t-test/ANOVA on perioperative factors. Multivariate analyses were performed to determined independent risk factors for short term outcomes., Results: 546 patients remained after propensity score matching, with 182 patients in each cohort. ACDF required the longest operative time 188 ± 79 versus laminectomy/fusion (169 ± 75, p = 0.017), and laminoplasty (167 ± 66, p = 0.004). ACDF required the shortest hospital stay (LOS ≥ 2: ACDF 56.6%, laminoplasty 89.6%, laminectomy/fusion 93.4%, p < 0.05). ACDF had lower overall complications (ACDF 3.9%, laminoplasty 7.7%, laminectomy/fusion 11.5%, p < 0.05), mortality (ACDF 0%, laminoplasty 0.55%, laminectomy/fusion 2.2%, p < 0.05), and unplanned readmissions (ACDF 4.4%, laminoplasty 4.4%, laminectomy/fusion 9.9%, p < 0.05). No significant differences were seen in the other outcomes including DVT/PT, acute renal failure, UTI, stroke, cardiac complications, or sepsis. In the multivariate analysis, laminectomy/fusion (OR 17, reference: ACDF) and laminoplasty (OR10, reference: ACDF) were strong independent risk factors for LOS ≥ 2 days. Laminectomy/fusion (OR 3.2, reference: ACDF) was an independent predictor for any adverse events 30-days after surgery., Conclusions: Laminectomy/fusion carries the highest risk for morbidity, mortality, and unplanned readmissions in the short-term postoperative period. Laminoplasty and ACDF cases carry similar short-term complications risks. ACDF is significantly associated with the longest operative duration and shortest LOS without an increase in individual or overall complications, readmissions, or reoperations.

Study Design: Cross-sectional, international survey., Objectives: To identify factors influencing pharmacologic anticoagulation initiation after spine surgery based on the AOSpine Anticoagulation Global Survey., Methods: This survey was distributed to the international membership of AOSpine (n = 3805). A Likert-type scale described grade practice-specific factors on a scale from low (1) to high (5) importance, and patient-specific factors a scale from low (0) to high (3) importance. Analysis was performed to determine which factors were significant in the decision making surrounding the initiation of pharmacologic anticoagulation., Results: A total of 316 spine surgeons from 64 countries completed the survey. In terms of practice-specific factors considered to initiate treatment, expert opinion was graded the highest (mean grade ± SD = 3.2 ± 1.3), followed by fellowship training (3.2 ± 1.3). Conversely, previous studies (2.7 ± 1.2) and unspecified guidelines were considered least important (2.6 ± 1.6). Patient body mass index (2.0 ± 1.0) and postoperative mobilization (2.3 ± 1.0) were deemed most important and graded highly overall. Those who rated estimated blood loss with greater importance in anticoagulation initiation decision making were more likely to administer thromboprophylaxis at later times (hazard ratio [HR] = 0.68-0.71), while those who rated drain output with greater importance were likely to administer thromboprophylaxis at earlier times (HR = 1.32-1.43)., Conclusion: Among our global cohort of spine surgeons, certain patient factors (ie, patient mobilization and body mass index) and practice-specific factors (ie, expert opinion and fellowship training) were considered to be most important when considering anticoagulation start times.

Study Design: Narrative review., Objectives: To discuss the importance of establishing diagnostic criteria in Degenerative Cervical Myelopathy (DCM), including factors that must be taken into account and challenges that must be overcome in this process., Methods: Literature review summarising current evidence of establishing diagnostic criteria for DCM., Results: Degenerative Cervical Myelopathy (DCM) is characterised by a degenerative process of the cervical spine resulting in chronic spinal cord dysfunction and subsequent neurological disability. Diagnostic delays lead to progressive neurological decline with associated reduction in quality of life for patients. Surgical decompression may halt neurologic worsening and, in many cases, improves function. Therefore, making a prompt diagnosis of DCM in order to facilitate early surgical intervention is a clinical priority in DCM., Conclusion: There are often extensive delays in the diagnosis of DCM. Presently, no single set of diagnostic criteria exists for DCM, making it challenging for clinicians to make the diagnosis. Earlier diagnosis and subsequent specialist referral could lead to improved patient outcomes using existing treatment modalities.

Study Design: Narrative Review., Objective: To (i) discuss why assessment and monitoring of disease progression is critical in Degenerative cervical myelopathy (DCM); (ii) outline the important features of an ideal assessment tool and (iii) discuss current and novel strategies for detecting subtle deterioration in DCM., Methods: Literature review., Results: Degenerative cervical myelopathy is an overarching term used to describe progressive injury to the cervical spinal cord by age-related changes of the spinal axis. Based on a study by Smith et al (2020), the prevalence of DCM is approximately 2.3% and is expected to rise as the global population ages. Given the global impact of this disease, it is essential to address important knowledge gaps and prioritize areas for future investigation. As part of the AO Spine RECODE-DCM (Research Objectives and Common Data Elements for Degenerative Cervical Myelopathy) project, a priority setting partnership was initiated to increase research efficiency by identifying the top ten research priorities for DCM. One of the top ten priorities for future DCM research was: What assessment tools can be used to evaluate functional impairment, disability and quality of life in people with DCM? What instruments, tools or methods can be used or developed to monitor people with DCM for disease progression or improvement either before or after surgical treatment?, Conclusions: With the increasing prevalence of DCM, effective surveillance of this population will require both the implementation of a monitoring framework as well as the development of new assessment tools.

Background: Creating a rectangular disc space is an important step during anterior cervical discectomy and fusion or cervical total disc replacement. The study aims to determine the accuracy of Caspar pin insertion by using a novel Adjustable Caspar Pin Aiming Device in anterior cervical procedures., Methods: Forty Caspar pins were placed using an Adjustable Caspar Pin Aiming Device in 20 human cadaveric cervical vertebral bodies from C3 to C7 after performing anterior discectomies. Accuracy of pin placement was assessed by lateral fluoroscopy, considering superior endplate slope (SE), inferior endplate slope (IE), Caspar pin slope (CP), and endplate-Caspar pin slope difference (SE/CP, IE/CP)., Results: The mean superior endplate slope (SE), inferior endplate slope (IE), and Caspar pin slope (CP) were 10.82 ± 2.3°, 10.32 ± 3.2°, and 15.58 ± 7.9°, respectively. The average superior endplate-Caspar pin slope difference (SE/CP) and inferior endplate-Caspar pin slope difference (IE/CP) were 6.6 ± 0.8° and 7.7 ± 0.8°, respectively. The greatest slope difference was observed at the superior and inferior endplates of C3. No cervical endplate violations occurred., Conclusion: Adjustable Caspar Pin Aiming Device allowed for a highly accurate Caspar pin placement with the average endplate-Caspar pin slope difference of less than 7.7°. It results in accurate placement of the superior and inferior Caspar pins parallel to the index vertebral endplates. Furthermore, it appears to facilitate the safe and effective insertion of Caspar pins for anterior cervical procedures.

Study Design: Retrospective cohort study., Objectives: Although cervical disc arthroplasty (CDA) has become a well-established and effective treatment for symptomatic cervical degeneration, many patients with multilevel disease are not good candidates for CDA at all levels. For such patients, hybrid surgery (HS)-a combination of adjacent anterior cervical discectomy and fusion (ACDF) and CDA-may be more appropriate. Given the novelty of HS and the relative dearth of studies adequately assessing short-term perioperative complications, this current study sought to assess the short-term morbidity profile of HS, differences in operative duration, length of stay (LOS), and readmission and reoperation rates and reasons relative to a 2-level ACDF cohort., Methods: All patients who underwent HS and 2-level ACDF were identified between 2011 and 2018 using a large, prospectively collected registry. Baseline patient characteristics and postoperative complications were compared using bivariate and/or multivariate analysis., Results: A total of 390 patients undergoing HS were identified. Two-level procedures were the most common (74.9%). Patients undergoing HS were more likely to be younger, male, and have fewer comorbidities. There were no differences between HS and 2-level ACDF in rates of any postoperative complication, transfusion, readmissions, and operative duration. However, HS had a decreased LOS (0.5 days), relative to a 2-level ACDF. HS patients had low rates of reoperation (1.28%) with 1 case for hematoma evacuation and another for revision CDA., Conclusions: This study represents one of the largest cohorts of patients undergoing HS reported to date. Patients undergoing HS are not at increased risk of perioperative complications relative to a 2-level ACDF and may benefit from shorter LOS.

Objectives: To summarize the current evidence on surgical treatment for large bridging osteophytes of the anterior cervical spine from Diffuse Idiopathic Skeletal Hyperostosis (DISH). Overview of Literature: In the current review, the surgical treatment of secondary dysphagia from DISH was the most useful treatment. We propose a treatment algorithm for management of this condition because currently there are only case reports and retrospective studies available. Methods: Literature search was performed using the MeSH terms "Anterior Cervical Osteophyte," "Diffuse Idiopathic Skeletal Hyperostosis (DISH)," and "Dysphagia" and "Treatment" for articles published between January 2000 and February 2020. PubMed search identified 117 articles that met the initial screening criteria. Detailed analysis identified the 40 best matching articles, following which the full inclusion and exclusion criteria left 11 articles for this review. Results: Incidence of secondary dysphagia was associated with DISH in elderly patients (average 65 years). The major clinical findings were dysphagia or respiratory compromise, with the most common level of bridging osteophytes of the cervical spine at C3-C5. There were 10 articles on surgical treatment involving anterior cervical osteophytectomy without fusion, 1 for multilevel cervical oblique corpectomy, 1 for anterior cervical discectomy with fusion plus plate, and 1 for anterior cervical osteophytectomy with stand-alone PEEK cage or plus plate. All the cases resulted in significant improvement without recurrence, with only 1 case having post-operative complications. Follow-up duration was 3-70.3 months. Conclusions: Surgical intervention for anterior cervical osteophytectomy appears to result in improved outcomes. However, there could be disadvantages concerning cervical spine motion if cervical osteophytectomy with cervical discectomy and fusion (ACDF) plus plate system is done.

Cervical disc arthroplasty (CDA) is a safe and effective option to improve clinical outcomes (e.g., NDI, VAS, and JOA) in degenerative cervical disc disease and compressive myelopathy. CDA's two main purported benefits have been that it maintains physiologic motion and thereby minimizes the biomechanical stresses placed on adjacent segments as compared to an ACDF. CDA might reduce the degeneration of adjacent segments, and the need for adjacent-level surgery. Reoperation rates of CDA have been reported to range from 1.8% to 5.4%, with a minimum 5-year follow-up. As the number of CDA procedures performed continues to increase, the need for revision surgery is also likely to increase. When performed skillfully in appropriate patients, CDA is an effective surgical technique to optimize clinical outcomes and radiological results. This review may assist surgical decision-making and enable a more effective and safer implementation of cervical arthroplasty for cervical degenerative disease.

Study Design: Retrospective cohort study., Objective: We aimed to evaluate the improvement in neurological deficit following early versus late decompression and stabilization of thoracolumbar junctional fractures., Methods: This is a retrospective evaluation of all patients with a traumatic spinal cord injury (SCI) from T11 to L2 treated at a teaching hospital between 2010 and 2017. Grouped analysis was performed comparing the cohort of patients who received early surgery within 24 hours (group 1) with those operated within 24 to 72 hours (group 2) and more than 72 hours after SCI (group 3). The primary outcome was the change in ASIA (American Spinal Injury Association) motor score at 12-month follow-up., Results: There were 317 patients (225 males and 92 females with mean age of 31.55 ± 12.43 years). A total of 144, 77, and 96 patients belonged to groups 1, 2, and 3 respectively. Improvement of at least 1 grade on ASIA classification was observed in 80, 45, and 33 patients in groups 1, 2, and 3 respectively ( P = .001). Overall, 32, 12, and 10 patients improved ≥2 grades on ASIA classification in groups 1, 2, and 3, respectively ( P = .069). On logistic regression analysis, early surgery and severity of initial injury (complete [ASIA A] vs incomplete SCI [ASIA B-D]) were found to significantly influence the potential for neurologic improvement ( P = .004 and P < .0001, respectively)., Conclusion: We believe that the earlier the decompression, the better. The 72-hour cutoff represents the most promising time window during which surgical decompression has the potential to confer a neuroprotective effect in the setting of incomplete SCI (ASIA B-D) in the distal region of the spinal cord (conus medullaris).

Study Design: Cross-sectional, international survey., Objectives: This study addressed the global perspectives concerning perioperative use of pharmacologic thromboprophylaxis during spine surgery along with its risks and benefits., Methods: A questionnaire was designed and implemented by expert members in the AO Spine community. The survey was distributed to AO Spine's spine surgeon members (N = 3805). Data included surgeon demographic information, type and region of practice, anticoagulation principles, different patient scenarios, and comorbidities., Results: A total of 316 (8.3% response rate) spine surgeons completed the survey, representing 64 different countries. Completed surveys were primarily from Europe (31.7%), South/Latin America (19.9%), and Asia (18.4%). Surgeons tended to be 35 to 44 years old (42.1%), fellowship-trained (74.7%), and orthopedic surgeons (65.5%) from academic institutions (39.6%). Most surgeons (70.3%) used routine anticoagulation risk stratification, irrespective of geographic location. However, significant differences were seen between continents with anticoagulation initiation and cessation methodology. Specifically, the length of a procedure ( P = .036) and patient body mass index ( P = .008) were perceived differently when deciding to begin anticoagulation, while the importance of medical clearance ( P < .001) and reference to literature ( P = .035) differed during cessation. For specific techniques, most providers noted use of mobilization, low-molecular-weight heparin, and mechanical prophylaxis beginning on postoperative 0 to 1 days. Conversely, bridging regimens were bimodal in distribution, with providers electing anticoagulant initiation on postoperative 0 to 1 days or days 5-6., Conclusion: This survey highlights the heterogeneity of spine care and accentuates geographical variations. Furthermore, it identifies the difficulty in providing consistent perioperative anticoagulation recommendations to patients, as there remains no widely accepted, definitive literature of evidence or guidelines.

Study Design: Narrative literature review., Objective: To review and present details on the occipitocervical fixation (OCF) technique as well as considerations for planning the procedure., Methods: We present the surgical technique of OCF in a step-by-step didactic and practical manner with surgical tips and tricks, including C1 and C2 screw fixation techniques. Additionally, we discuss complications, the extension of fusion, types of OCF, and how to avoid common side effects associated with OCF., Results: The complex and mobile anatomy of the craniocervical junction, when requiring fixation and fusion, warrants rigid instrumentation that can be achieve using a modern screw-plate-rod construct. Indications for OCF are craniocervical instability, and atlantoaxial instability when selective atlantoaxial fusion is not feasible. OCF generally involves occiput-C2 fusion. C1 fixation is generally unnecessary, since it increases the surgical time and is associated with the risk of vascular complications. Selective occiput-C2 fusion is recommended when there is no need for including the cervical subaxial region (eg, when stenosis or fractures coexist in the subaxial spine), and good fixation is achieved at C2. Most instrumentation systems now have occipital plates that are not pre-integrated to rods, making fixation much simpler. Surgical steps, from position to wound closure, are presented in detail, with pearls for practice and discussion of cervical alignment., Conclusions: OCF is a challenging procedure, with potential risk of severe adverse effects. Understanding the surgical indications, as well as the nuances of the surgical technique, is required to improve patient outcomes and avoid complications.

Study Design: Broad narrative review., Objective: To review and summarize the current literature on guidelines, outcomes, techniques and indications surrounding multiple modalities of minimizing blood loss in spine surgery., Methods: A thorough review of peer-reviewed literature was performed on the guidelines, outcomes, techniques, and indications for multiple modalities of minimizing blood loss in spine surgery., Results: There is a large body of literature that provides a consensus on guidelines regarding the appropriate timing of discontinuation of anticoagulation, aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), and herbal supplements prior to surgery. Additionally, there is a more heterogenous discussion the utility of preoperative autologous blood donation facilitated by erythropoietin and iron supplementation for healthy patients slated for procedures with high anticipated blood loss and for whom allogeneic transfusion is likely. Intraoperative maneuvers available to minimize blood loss include positioning and maintaining normothermia. Tranexamic acid (TXA), bipolar sealer electrocautery, and topical hemostatic agents, and hypotensive anesthesia (mean arterial pressure (MAP) <65 mm Hg) should be strongly considered in cases with larger exposures and higher anticipated blood loss. There is strong level 1 evidence for the use of TXA in spine surgery as it reduces the overall blood loss and transfusion requirements., Conclusion: As the volume and complexity of spinal procedures rise, intraoperative blood loss management has become a pivotal topic of research within the field. There are many tools for minimizing blood loss in patients undergoing spine surgery. The current literature supports combining techniques to use a cost- effective multimodal approach to minimize blood loss in the perioperative period., 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: Many of the authors have affiliations with organizations with financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in some of the products mentioned in the study. There are no conflicts of interest in reference to any product mentioned in the content of this article., (© The Author(s) 2020.)

Study Design: Literature review., Objectives: Surgical site infection (SSI) following spine surgery leads to significant patient morbidity, mortality, and increased health care costs. The purpose of this article is to identify risk factors and strategies to prevent SSIs following spine surgery, with particular focus on avoiding infections in posterior cervical surgery., Methods: We performed a literature review and synthesis to identify methods that can be used to prevent the development of SSI following spine surgery. Specific pearls for preventing infection in posterior cervical spine surgery are also presented., Results: SSI prevention can be divided into patient and surgeon factors. Preoperative patient factors include smoking cessation, tight glycemic control, weight loss, and nutrition optimization. Surgeon factors include screening and treatment for pathologic microorganisms, skin preparation using chlorhexidine and alcohol, antimicrobial prophylaxis, hand hygiene, meticulous surgical technique, frequent irrigation, intrawound vancomycin powder, meticulous multilayered closure, and use of closed suction drains., Conclusion: Prevention of SSI following spine surgery is multifactorial and begins with careful patient selection, preoperative optimization, and meticulous attention to numerous surgical factors. With careful attention to various patient and surgeon factors, it is possible to significantly reduce SSI rates following spine surgery., 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., (© The Author(s) 2020.)

Study Design: Epidemiological retrospective study., Objective: To describe the demographics, timing to surgery, delay, short-term neurological recovery, and complications in surgically treated subaxial cervical trauma in a resource-constrained country., Methods: Thirty consecutive subaxial cervical trauma patients presenting to a trauma hospital in Nepal between December 2015 and August 2017 were analyzed as a retrospective cohort. Patients were segregated into 4 groups based on the timing to surgery: within 2 days, 3 to 7 days, 8 to 30 days, and >31 days., Results: There were 27 male and 3 female patients with mean age 40 years. Twenty-four sustained fall injury, and 27 patients were from outside Kathmandu. No patients were treated within the first 48 hours; only 9 were treated between 3 and 7 days, 16 between 8 and 30 days, and 5 a month later. Major delay was finance and operating room availability. Thirteen patients had a C6C7 involvement followed by C5C6 in 6 patients. Seven patients had complete neurological deficit while 18 patients had incomplete deficit. A total of 46.7% improved their neurology in 6 months. No neurological recovery was observed in complete deficit patients., Conclusion: Seventy percent of our patients were treated longer than 1 week after injury, which would likely be considered unacceptable in most first world countries. As expected, the outcomes for many of these patients were far worse than reported in North American centers with early access to medical care and insurance. Despite this, nearly half of our patients improved neurologically following treatment; hence, surgery holds hope of some restoration of neurologic deficits., 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: K. Daniel Riew: Biomet, Medtronic—Royalties. Osprey, Expanding Orthopedics, Spineology, Spinal Kinetics, Nexgen Spine, Amedica, Vertiflex, Benvenue, Paradigm Spine, PSD—Stock. Spine, GSJ, ESJ, Neurosurgery, Clinics in Orthopedics, Spine Surgery Today—Editorial/Board. AO Spine—Board. The remaining authors have no conflicts of interest to disclose.

Study Design: A retrospective cohort study., Objective: To investigate factors influencing the incidence of moderate to severe postoperative axial neck pain following cervical laminoplasty., Methods: We reviewed 125 patients with cervical myelopathy who underwent double-door laminoplasty. The primary outcomes were the Numerical Rating Scale score (NRS score, 0-10) for neck pain, the Short Form 36 (SF-36) Health Survey score (Physical and Mental Component Summary scores [PCS and MCS, respectively]), and satisfaction. Imaging parameters on plain radiographs and magnetic resonance imaging were also evaluated. Patients with moderate to severe postoperative neck pain (NRS ≥ 5) were compared with those with no or mild neck pain (NRS ≤ 4)., Results: One hundred and three patients (82%) with complete data were eligible for inclusion. There were 67 men and 36 women, with a mean age of 65 years (32-89 years). Twenty-five patients (23%) had moderate to severe postoperative axial pain (NRS ≥ 5) and were compared with the other 78 patients (NRS ≤ 4), which revealed several predictive factors, including female sex, the presence of preoperative neck pain, low postoperative PCS, low preoperative and postoperative MCS, and satisfaction with the treatment. Multivariable logistic regression analysis revealed that the postoperative MCS ( P = .002) was a risk factor for postoperative neck pain, although the preoperative MCS did not reach statistical significance ( P = .06)., Conclusions: Patients with a low mental state, possibly before surgery, are at a high risk for postoperative axial neck pain. None of the imaging parameters were statistically different., 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 Riew reports personal fees from Biomet, Medtronic; other support from Nexgen, Amedica, Vertiflex, Benvenue, Spinal Kinetics, Spineology, Expanding Orthopedics, Osprey, Paradigm Spine, PSD; other support from Biomet, Medtronic; personal fees from Zeiss Teaching Webinar; other support from AO Spine; personal fees from AO Spine; other support from Advanced Medical, outside the submitted work. Dr Tanaka has received honoraria from Amgen Inc, Asahi Kasei Pharma Corporation, Amgen Astellas BioPharma K.K., Kyocera Medical Corporation, Daiichi Sankyo Company, Limited, Teijin Pharma Limited, Eli Lilly Japan K.K., Pfizer Japan Inc; endowments from Astellas Pharma Inc, Ayumi Pharmaceutical Corporation, BristolMyers Squibb, Pfizer Japan Inc, Daiichi Sankyo Company Limited, Chugai Pharmaceutical Co, Ltd; and grants from The Japan Agency for Medical Research and Development (AMED), Japan Society for the Promotion of Science (JSPS)/Grant-in-Aid for Scientific Research (A), and the Japan Society for the Promotion of Science (JSPS)/Grant-in-Aid for Exploratory Research. Dr Oshima, Dr Matsubayashi, Dr Taniguchi, Dr Hayakawa, Dr Fukushima, Dr Oichi, and Dr Oka have no conflicts of interest to disclose.

Study Design: Retrospective cohort study., Objective: Factors that predict outcomes for adult cervical spine deformity (ACSD) have not been well defined. To compare ACSD patients with best versus worst outcomes., Methods: This study was based on a prospective, multicenter observational ACSD cohort. Best versus worst outcomes were compared based on Neck Disability Index (NDI), Neck Pain Numeric Rating Scale (NP-NRS), and modified Japanese Orthopaedic Association (mJOA) scores., Results: Of 111 patients, 80 (72%) had minimum 1-year follow-up. For NDI, compared with best outcome patients (n = 28), worst outcome patients (n = 32) were more likely to have had a major complication ( P = .004) and to have undergone a posterior-only procedure ( P = .039), had greater Charlson Comorbidity Index ( P = .009), and had worse postoperative C7-S1 sagittal vertical axis (SVA; P = .027). For NP-NRS, compared with best outcome patients (n = 26), worst outcome patients (n = 18) were younger ( P = .045), had worse baseline NP-NRS ( P = .034), and were more likely to have had a minor complication ( P = .030). For the mJOA, compared with best outcome patients (n = 16), worst outcome patients (n = 18) were more likely to have had a major complication ( P = .007) and to have a better baseline mJOA ( P = .030). Multivariate models for NDI included posterior-only surgery ( P = .006), major complication ( P = .002), and postoperative C7-S1 SVA ( P = .012); models for NP-NRS included baseline NP-NRS ( P = .009), age ( P = .017), and posterior-only surgery ( P = .038); and models for mJOA included major complication ( P = .008)., Conclusions: Factors distinguishing best and worst ACSD surgery outcomes included patient, surgical, and radiographic factors. These findings suggest areas that may warrant greater awareness to optimize patient counseling and outcomes., 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.

Study Design: Systematic review., Objectives: Diagnosis of pseudarthrosis after anterior cervical fusion is difficult, and often depends on the surgeon's subjective assessment because recommended radiographic criteria are lacking. This review evaluated the available evidence for confirming fusion after anterior cervical surgery., Methods: Articles describing assessment of anterior cervical fusion were retrieved from MEDLINE and SCOPUS. The assessment methods and fusion rates at 1 and 2 years were evaluated to identify reliable radiographical criteria., Results: Ten fusion criteria were described. The 4 most common were presence of bridging trabecular bone between the endplates, absence of a radiolucent gap between the graft and endplate, absence of or minimal motion between adjacent vertebral bodies on flexion-extension radiographs, and absence of or minimal motion between the spinous processes on flexion-extension radiographs. The mean fusion rates were 90.2% at 1 year and 94.7% at 2 years. The fusion rate at 2 years had significant independence ( P = .048)., Conclusions: The most common fusion criteria, bridging trabecular bone between the endplates and absence of a radiolucent gap between the graft and endplate, are subjective. We recommend using <1 mm of motion between spinous processes on extension and flexion to confirm 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 Riew owns stock in Osprey, Expanding Orthopedics, Spineology, Spinal Kinetics, and Nexgen Spine and receives honorarium from Advanced Medical, Grand Rounds, Medtronic, Zeiss, and Zimmer Biomet. Dr Tanaka has received honoraria from Amgen Inc, Asahi Kasei Pharma Corporation, Amgen Astellas BioPharma K.K., Kyocera Medical Corporation, Daiichi Sankyo Company, Limited, Teijin Pharma Limited., Eli Lilly Japan K.K., Pfizer Japan Inc, endowments from Astellas Pharma Inc, Ayumi Pharmaceutical Corporation, Bristol-Myers Squibb, Pfizer Japan Inc, Daiichi Sankyo Company Limited, Chugai Pharmaceutical Co, Ltd, and grants from The Japan Agency for Medical Research and Development (AMED), Japan Society for the Promotion of Science (JSPS)/Grant-in-Aid for Scientific Research (A), and the Japan Society for the Promotion of Science (JSPS)/Grant-in-Aid for Exploratory Research.

Study Design: A narrative literature review., Objectives: To review the surgical techniques of posterior screw fixation in the subaxial cervical spine., Methods: A broad literature review on the most common screw fixation techniques including lateral mass, pedicle, intralaminar and transfacet screws was performed on PubMed. The techniques and surgical nuances are summarized., Results: The following techniques were described in detail and presented with illustrative figures, including (1) lateral mass screw insertion: by Roy-Camille, Louis, Magerl, Anderson, An, Riew techniques and also a modified technique for C7 lateral mass fixation; (2) pedicle screw fixation technique as described by Abumi and also a freehand technique description; (3) intralaminar screw fixation; and finally, (4) transfacet screw fixation, as described by Takayasu, DalCanto, Klekamp, and Miyanji., Conclusions: Many different techniques of subaxial screw fixation were described and are available. To know the nuances of each one allows surgeons to choose the best option for each patient, improving the success of the fixation and decrease complications., 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.

Study Design: Cross-sectional study., Objectives: To continue the line of a previous publication using steroid for acute spinal cord injury (SCI) by spine surgeons from Latin America (LA) and assess the current status of methylprednisolone (MP) prescription in Europe (EU), Asia Pacific (AP), North America (NA), and Middle East (ME) to determine targets for educational activities suitable for each region., Methods: The English version of a previously published questionnaire was used to evaluate opinions about MP administration in acute SCI in LA, EU, AP, NA, and ME. This Internet-based survey was conducted by members of AOSpine. The questionnaire asked about demographic features, background with management of spine trauma patients, routine administration of MP in acute SCI, and reasons for MP administration., Results: A total of 2659 responses were obtained for the electronic questionnaire from LA, EU, AP, NA, and ME. The number of spine surgeons that treat SCI was 2206 (83%). The steroid was used by 1198 (52.9%) surgeons. The uses of MP were based predominantly on the National Acute Spinal Cord Injury Study III study (n = 595, 50%). The answers were most frequently given by spine surgeons from AP, ME, and LA. These regions presented a statistically significant difference from North America ( P < .001). The number of SCI patients treated per year inversely influenced the use of MP. The higher the number of patients treated, the lower the administration rates of MP observed., Conclusions: The study identified potential targets for educational campaigns, aiming to reduce inappropriate practices of MP administration., 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.

Study Design: Systematic review., Objectives: Degenerative disc disease and spondylosis resulting in radiculopathy and retrodiscal myelopathy are among the most frequently encountered cervical spinal disorders. Traditionally, anterior cervical discectomy and fusion (ACDF) has successfully achieved neural decompression and restored intradiscal height in these conditions. Unfortunately, nonunion and iatrogenic adjacent segment pathology associated with fusion procedures in the cervical spine has led to an interest in motion-preserving procedures. Cervical disc arthroplasty (CDA) was developed in hopes of preserving cervical biomechanics while mitigating the complications associated with ACDF. Through a systematic review of both published and ongoing studies on single- and multilevel CDA, and hybrid surgeries, we aim to provide evidence for their safety and efficacy in the treatment of various cervical pathologies., Methods: A systematic search of several large databases, including Cochrane Central, PubMed, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry was conducted to identify published studies and ongoing clinical trials on CDA and hybrid surgery., Results: Among the relevant studies reviewed, 3 were randomized controlled trials, 2 systematic reviews, as well as multiple prospective case series, biomechanical studies, and meta-analyses., Conclusion: Over the past decade, multiple high-quality studies have shown that single-level CDA can offer equivalent clinical outcomes with a reduction in secondary procedures and total cost when compared to ACDF. However, more recently there has been an increasing prevalence of 2-level CDA and hybrid surgery. Although the data regarding these multilevel procedures is less robust, it appears that they may be as effective as their single-level counterparts., 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 Riew reports personal fees from AOSpine, various universities for visiting professorships, personal fees from Biomet, Medtronic, other support from Expanding Orthopaedics, personal fees from Expert Testimony, grants from Medtronic, other support from Amedica, Benvenue, Nexgen Spine, Paradigm Spine, Spinal Kinetics, Spineology, Vertiflex, and outside the submitted work.

Study Design: Retrospective study., Objectives: To evaluate the efficacy of bilateral C4-5 foraminotomy in preventing occurrence of postoperative C5 palsy and to identify possible risk factors for its development., Methods: A total of 70 consecutive patients who underwent open-door laminoplasty with bilateral C4-5 foraminotomy were included. Clinical, radiographic, and operative data was reviewed. Development of postoperative C5 palsy was analyzed., Results: A total of 54 males and 16 females were reviewed. Mean age was 56 years (range, 30-86 years). The primary pathology was spondylosis in 76% of cases and ossified posterior longitudinal ligament in 21%. Radiographic evidence of C4-5 foraminal stenosis was seen in 81% of the patients. The mean duration of preoperative symptoms was 7 ± 19 months. Four (5.7%) out of 70 patients developed C5 palsy after open-door laminoplasty with bilateral C4-5 foraminotomy. Multivariate analysis showed that a long duration of preoperative symptoms (>12 months) and the presence of preoperative C4-5 T2-MRI cord signal change were statistically significant risk factors for the development of C5 palsy even after bilateral C4-5 foraminotomy in open-door laminoplasty ( P < .0001 and P = .036, respectively)., Conclusions: Prophylactic bilateral C4-5 foraminotomies do not completely eliminate the occurrence of C5 palsy. Prolonged duration of symptoms and presence of preoperative T2-MRI cord signal change increase the risk for developing postoperative C5 palsy despite foraminotomy., 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.

Degenerative cervical myelopathy (DCM) is a progressive spine disease and the most common cause of spinal cord dysfunction in adults worldwide. Patients with DCM may present with common signs and symptoms of neurological dysfunction, such as paresthesia, abnormal gait, decreased hand dexterity, hyperreflexia, increased tone, and sensory dysfunction. Clinicians across several specialties encounter patients with DCM, including primary care physicians, rehabilitation specialists, therapists, rheumatologists, neurologists, and spinal surgeons. Currently, there are no guidelines that outline how to best manage patients with mild (defined as a modified Japanese Orthopedic Association (mJOA) score of 15-17), moderate (mJOA = 12-14), or severe (mJOA ≤ 11) myelopathy, or nonmyelopathic patients with evidence of cord compression. This guideline provides evidence-based recommendations to specify appropriate treatment strategies for these populations. The intent of our recommendations is to (1) help identify patients at high risk of neurological deterioration, (2) define the role of nonoperative and operative management in each patient population, and (3) determine which patients are most likely to benefit from surgical intervention. The ultimate goal of these guidelines is to improve outcomes and reduce morbidity in patients with DCM by promoting standardization of care and encouraging clinicians to make evidence-informed decisions., 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.

Study Design: Guideline development., Objectives: The objective of this study is to develop guidelines that outline how to best manage (1) patients with mild, moderate, and severe myelopathy and (2) nonmyelopathic patients with evidence of cord compression with or without clinical symptoms of radiculopathy., Methods: Five systematic reviews of the literature were conducted to synthesize evidence on disease natural history; risk factors of disease progression; the efficacy, effectiveness, and safety of nonoperative and surgical management; the impact of preoperative duration of symptoms and myelopathy severity on treatment outcomes; and the frequency, timing, and predictors of symptom development. A multidisciplinary guideline development group used this information, and their clinical expertise, to develop recommendations for the management of degenerative cervical myelopathy (DCM)., Results: Our recommendations were as follows: (1) "We recommend surgical intervention for patients with moderate and severe DCM." (2) "We suggest offering surgical intervention or a supervised trial of structured rehabilitation for patients with mild DCM. If initial nonoperative management is pursued, we recommend operative intervention if there is neurological deterioration and suggest operative intervention if the patient fails to improve." (3) "We suggest not offering prophylactic surgery for non-myelopathic patients with evidence of cervical cord compression without signs or symptoms of radiculopathy. We suggest that these patients be counseled as to potential risks of progression, educated about relevant signs and symptoms of myelopathy, and be followed clinically." (4) "Non-myelopathic patients with cord compression and clinical evidence of radiculopathy with or without electrophysiological confirmation are at a higher risk of developing myelopathy and should be counselled about this risk. We suggest offering either surgical intervention or nonoperative treatment consisting of close serial follow-up or a supervised trial of structured rehabilitation. In the event of myelopathic development, the patient should be managed according to the recommendations above.", Conclusions: These guidelines will promote standardization of care for patients with DCM, decrease the heterogeneity of management strategies and encourage clinicians to make evidence-informed decisions., 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.

Study Design: Retrospective analysis of consecutive case series., Objective: To introduce a novel method of stabilizing the cranium using bivector traction in posterior cervical fusions., Methods: A retrospective review of 50 consecutive patients undergoing instrumented posterior cervical arthrodesis was performed. All patients had at least 3 levels of subaxial fusion using the bivector traction apparatus. Patients' demographic data was recorded for the following: pre- and postoperative cervical lordosis, pre- and postoperative cervical sagittal vertical alignment (cSVA), and intraoperative complications from pin placements., Results: A total of 50 patients were studied. There were 31 females and 19 males. The mean age at the time of surgery was 49 years (range 35-79). A mean 5.8 levels were fused. The most common levels fused were C2-T3 in 14 patients followed by C2-T2 in 7 patients. In no case did the surgeon or assistant have to scrub out to adjust the alignment. The mean pre- and postoperative cervical lordosis was -6.0° and -10°, respectively ( P = .04). The mean pre-and postoperative cSVA was 30.5 mm and 32 mm, respectively ( P = .6). There were no complications related to placement of the Gardner-Well tongs., Conclusion: The bivector traction is an easy, safe, and effective method of stabilizing the head and obtaining adequate cervical sagittal alignment., 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.

Study Design: Multi-institutional retrospective case series of 8887 patients who underwent anterior cervical spine surgery., Objective: Anterior decompression from discectomy or corpectomy is not without risk. Surgical morbidity ranges from 9% to 20% and is likely underreported. Little is known of the incidence and effects of rare complications on functional outcomes following anterior spinal surgery. In this retrospective review, we examined implant extrusions (IEs) following anterior cervical fusion., Methods: A retrospective multicenter case series study involving 21 high-volume surgical centers from the AOSpine North America Clinical Research Network. Medical records for 17 625 patients who received cervical spine surgery (levels from C2 to C7) between January 1, 2005, and December 31, 2011, were reviewed to identify occurrence of 21 predefined treatment complications., Results: Following anterior cervical fusion, the incidence of IE ranged from 0.0% to 0.8% across 21 institutions with 11 cases reported. All surgeries involved multiple levels, and 7/11 (64%) involved either multilevel corpectomies or hybrid constructs with at least one adjacent discectomy to a corpectomy. In 7/11 (64%) patients, constructs ended with reconstruction or stabilization at C7. Nine patients required surgery for repair and stabilization following IE. Average length of hospital stay after IE was 5.2 days. Only 2 (18%) had residual deficits after reoperation., Conclusions: IE is a very rare complication after anterior cervical spine surgery often requiring revision. Constructs requiring multilevel reconstruction, especially at the cervicothoracic junction, have a higher risk for failure, and surgeons should proceed with caution in using an anterior-only approach in these demanding cases. Surgeons can expect most patients to regain function after reoperation., 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: Gabriel A. Smith reports grants from AOSpine North America during the conduct of the study; Jonathan Pace reports grants from AOSpine North America during the conduct of the study; Thomas E. Mroz reports other from AOSpine during the conduct of the study, personal fees from Stryker, personal fees from Ceramtec, and other from Pearl Diver, outside the submitted work; Robert A. Hart reports grants from AOSpine North America during the conduct of the study other from CSRS Board, other from ISSLS, other from ISSG Exec Committee, personal fees from DepuySynthes, personal fees from Globus, personal fees from Medtronic, other from Evans, Craven & Lackie, other from Benson, Bertoldo, Baker, & Carter, grants from Medtronic, grants from ISSGF, personal fees from Seaspine, personal fees from DepuySynthes, other from Spine Connect, personal fees from DepuySynthes, outside the submitted work; Alan S. Hilibrand reports grants from AOSpine North America during the conduct of the study, other from Amedica, Vertiflex, Benvenue, Lifespine, Paradigm Spine, PSD, Spinal Ventures, outside the submitted work, and in addition, Dr. Hilibrand has a patent Aesculap, Amedica, Biomet, Stryker, Alphatec, with royalties paid; David B. Bumpass reports grants from AOSpine North America during the conduct of the study, grants from North American Spine Society, personal fees from Doximity, personal fees from Gerson Lehrman Group, outside the submitted work; Ziya Gokaslan reports grants from AOSpine North America, personal fees from AO Foundation, grants from AOSpine, outside the submitted work; Jeremy L. Fogelson reports grants from AOSpine North America during the conduct of the study, and Previous Consultant for one day to Depuy-Synthes in March, 2014; Eric M. Massicotte reports grants from AOSpine North America during the conduct of the study, grants from Medtronic, Depuy-Synthes Spine Canada, personal fees from Watermark Consulting, grants from AOSpine North America, nonfinancial support from AOSpine North America, outside the submitted work; K. Daniel Riew reports personal fees from AOSpine International, other from Global Spine Journal, other from Spine Journal, other from Neurosurgery, personal fees from Multiple Entities for defense, plantiff, grants from AOSpine, grants from Cerapedics, grants from Medtronic, personal fees from AOSpine, personal fees from NASS, personal fees from Biomet, personal fees from Medtronic, nonfinancial support from Broadwater, outside the submitted work; Michael P. Steinmetz reports grants from AOSpine North America during the conduct of the study; Dr. Corriveau reports grants from AOSNA during the conduct of the study; Dr. Lee reports grants from AOSpine North America during the conduct of the study; Dr. Nassr reports grants from AO Spine North America, during the conduct of the study; Dr. Arnold reports grants from AOSpine North America during the conduct of the study; other from Z-Plasty, other from Medtronic Sofamore Danek, other from Stryker Spine, other from FzioMed, other from AOSpine North America, other from Life Spine, other from Integra Life, other from Spine Wave, other from MIEMS, other from Cerapedics, other from AOSpine North America, outside the submitted work; Dr. Bydon reports grants from AOSpine North America during the conduct of the study.

Study Design: Retrospective multicenter case series study., Objective: Because cervical dural tears are rare, most surgeons have limited experience with this complication. A multicenter study was performed to better understand the presentation, treatment, and outcomes following cervical dural tears., Methods: Multiple surgeons from 23 institutions retrospectively identified 21 rare complications that occurred between 2005 and 2011, including unintentional cervical dural tears. Demographic data and surgical history were obtained. Clinical outcomes following surgery were assessed, and any reoperations were recorded. Neck Disability Index (NDI), modified Japanese Orthopaedic Association (mJOA), Nurick classification (NuC), and Short-Form 36 (SF36) scores were recorded at baseline and final follow-up at certain centers. All data were collected, collated, and analyzed by a private research organization., Results: There were 109 cases of cervical dural tears among 18 463 surgeries performed. In 101 cases (93%) there was no clinical sequelae following successful dural tear repair. There were statistical improvements ( P < .05) in mJOA and NuC scores, but not NDI or SF36 scores. No specific baseline or operative factors were found to be associated with the occurrence of dural tears. In most cases, no further postoperative treatments of the dural tear were required, while there were 13 patients (12%) that required subsequent treatment of cerebrospinal fluid drainage. Analysis of those requiring further treatments did not identify an optimum treatment strategy for cervical dural tears., Conclusions: In this multicenter study, we report our findings on the largest reported series (n = 109) of cervical dural tears. In a vast majority of cases, no subsequent interventions were required and no clinical sequelae were observed., 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: Kevin R. O'Neill reports grants from AOSpine North America during the conduct of the study; Michael G. Fehlings reports grants from AOSpine North America during the conduct of the study; Thomas E. Mroz reports other from AOSpine, grants from AOSpine North America, during the conduct of the study, personal fees from Stryker, personal fees from Ceramtec, other from Pearl Diver, outside the submitted work; Zachary A. Smith reports grants from AOSpine North America during the conduct of the study; Wellington K. Hsu reports grants from AOSpine North America during the conduct of the study, personal fees from Medtronic, personal fees from Stryker, personal fees from Bacterin, personal fees from Graftys, personal fees from Ceramtec, personal fees from Relievant, personal fees from Bioventus, personal fees from Globus, personal fees from SpineSmith, outside the submitted work; Michael P. Steinmetz reports grants from AOSpine North America during the conduct of the study; Praveen V. Mummaneni reports grants from AOSpine North America during the conduct of the study, other from Depuy Spine, grants and other from AOSpine, other from Globus, other from Springer Publishers, other from Thieme Publishers, other from Taylor and Francis Publishers, other from Spincity/ISD, outside the submitted work; Dean Chou reports grants from AOSpine North America during the conduct of the study, other from Globus, other from Orthofix, other from Medtronic, outside the submitted work; Ahmad Nassr reports grants from AOSpine North America during the conduct of the study; Sheeraz A. Qureshi reports grants from AOSpine North America during the conduct of the study, and is a consultant and receive royalties from Stryker Spine, Biomet Spine, and RTI; Evan O. Baird reports grants from AOSpine North America during the conduct of the study; Justin S. Smith reports grants from AOSpine North America during the conduct of the study, personal fees from Biomet, personal fees from Nuvasive, personal fees from Cerapedics, personal fees from K2M, personal fees from Globus, personal fees from DePuy, outside the submitted work; Christopher Shaffrey reports grants from AOSpine North America during the conduct of the study, personal fees from Biomet, personal fees from Medtronic, from Nuvasive, personal fees from K2M, personal fees from Stryker, outside the submitted work, and Editorial Board Spine, Spinal Deformity and Neurosurgery; Chadi A. Tannoury reports grants from AOSpine North America during the conduct of the study; Tony Tannoury reports grants from AOSpine North America during the conduct of the study; Ziya L. Gokaslan reports grants from AOSpine North America during the conduct of the study, grants from AOSpine North America, personal fees from AO Foundation, grants from AOSpine, outside the submitted work; Jeffrey L. Gum reports grants from AOSpine North America during the conduct of the study, personal fees from Medtronic, Alphatec, Stryker, LifeSpine, Acuity, Pacira, PAKmed, Gerson Lehrman Group, personal fees from OREF, AOSpine, personal fees from Acuity, other from Medtronic, personal fees from MiMedx, Pacira Pharmaceuticals, Alphatec, grants from Fischer Owen Fund, nonfinancial support from American Journal of Orthopaedics, nonfinancial support from American Journal of Orthopaedics, The Spine Journal, outside the submitted work; Robert A. Hart reports grants from AOSpine North America during the conduct of the study, other from CSRS Board, other from ISSLS, other from ISSG Executive Commitee, personal fees from DepuySynthes, personal fees from Globus, personal fees from Medtronic, other from Evans, Craven & Lackie, other from Benson, Bertoldo, Baker, & Carter, grants from Medtronic, grants from ISSGF, personal fees from Seaspine, personal fees from DepuySynthes, other from Spine Connect, personal fees from DepuySynthes, outside the submitted work; Robert E. Isaacs reports grants from AOSpine North America during the conduct of the study, grants and personal fees from NuVasive, Inc., personal fees from Association for Collaborative Spine research, outside the submitted work; David B. Bumpass reports grants from AOSpine North America during the conduct of the study, grants from North American Spine Society, personal fees from Doximity, personal fees from Gerson Lehrman Group, outside the submitted work; Adeeb Derakhshan reports grants from AOSpine North America during the conduct of the study; Eric M. Massicotte reports grants from AOSpine North America during the conduct of the study, grants from Medtronic, Depuy-Synthes Spine Canada, personal fees from Watermark Consulting, grants from AOSpine North America, nonfinancial support from AOSpine North America, outside the submitted work; Jonathan R. Pace reports grants from AOSpine North America during the conduct of the study; Gabriel A. Smith reports grants from AOSpine North America during the conduct of the study; Khoi D. Than reports grants from AOSpine North America during the conduct of the study; K. Daniel Riew reports personal fees from AOSpine International, other from Global Spine Journal, other from Spine Journal, other from Neurosurgery, personal fees from Multiple Entities for defense, plantiff, grants from AOSpine, grants from Cerapedics, grants from Medtronic, personal fees from AOSpine, personal fees from NASS, personal fees from Biomet, personal fees from Medtronic, non-financial support from Broadwater, outside the submitted work.

Study Design: Retrospective, multicenter case-series study and literature review., Objectives: To determine the prevalence of brachial plexopathy after cervical spine surgery and to review the literature to better understand the etiology and risk factors of brachial plexopathy after cervical spine surgery., Methods: A retrospective case-series study of 12 903 patients at 21 different sites was performed to analyze the prevalence of several different complications, including brachial plexopathy. A literature review of the US National Library of Medicine and the National Institutes of Health (PubMed) database was conducted to identify articles pertaining to brachial plexopathy following cervical spine surgery., Results: In our total population of 12 903 patients, only 1 suffered from postoperative brachial plexopathy. The overall prevalence rate was thus 0.01%, but the prevalence rate at the site where this complication occurred was 0.07%. Previously reported risk factors for postoperative brachial plexopathy include age, anterior surgical procedures, and a diagnosis of ossification of the posterior longitudinal ligament. The condition can also be due to patient positioning during surgery, which can generally be detected via the use of intraoperative neuromonitoring., Conclusions: Brachial plexopathy following cervical spine surgery is rare and merits further study., 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: Khoi D. Than reports grants from AOSpine North America during the conduct of the study; Praveen V. Mummaneni reports grants from AOSpine North America during the conduct of the study, other from Depuy Spine, grants and other from AOSpine, other from Globus, other from Springer Publishers, other from Thieme Publishers, other from Taylor and Francis Publishers, other from Spincity/ISD, outside the submitted work; Wellington K. Hsu reports grants from AOSpine North America during the conduct of the study, personal fees from Medtronic, personal fees from Stryker, personal fees from Bacterin, personal fees from Graftys, personal fees from Ceramtec, personal fees from Relievant, personal fees from Bioventus, personal fees from Globus, personal fees from SpineSmith, outside the submitted work; Michael G. Fehlings reports grants from AOSpine North America during the conduct of the study; Thomas E. Mroz reports other from AO Spine, during the conduct of the study, personal fees from Stryker, personal fees from Ceramtec, other from Pearl Diver, outside the submitted work; and K. Daniel Riew reports personal fees from AOSpine International, other from Global Spine Journal, other from Spine Journal, other from Neurosurgery, personal fees from Multiple Entities for defense, plantiff, grants from AOSpine, grants from Cerapedics, grants from Medtronic, personal fees from AOSpine, personal fees from NASS, personal fees from Biomet, personal fees from Medtronic, nonfinancial support from Broadwater, outside the submitted work; Zachary A. Smith reports grants from AOSpine North America, during the conduct of the study; Paul M. Arnold reports grants from AOSpine North America, during the conduct of the study; other from Z-Plasty, other from Medtronic Sofamore Danek, other from Stryker Spine, other from FzioMed, other from AOSpine North America, other from Life Spine, other from Integra Life, other from Spine Wave, other from MIEMS, other from Cerapedics, other from AOSpine North America, outside the submitted work.

Study Design: A multicentered retrospective case series., Objective: To determine the incidence and circumstances surrounding the development of a symptomatic postoperative epidural hematoma in the cervical spine., Methods: Patients who underwent cervical spine surgery between January 1, 2005, and December 31, 2011, at 23 institutions were reviewed, and all patients who developed an epidural hematoma were identified., Results: A total of 16 582 cervical spine surgeries were identified, and 15 patients developed a postoperative epidural hematoma, for a total incidence of 0.090%. Substantial variation between institutions was noted, with 11 sites reporting no epidural hematomas, and 1 site reporting an incidence of 0.76%. All patients initially presented with a neurologic deficit. Nine patients had complete resolution of the neurologic deficit after hematoma evacuation; however 2 of the 3 patients (66%) who had a delay in the diagnosis of the epidural hematoma had residual neurologic deficits compared to only 4 of the 12 patients (33%) who had no delay in the diagnosis or treatment ( P = .53). Additionally, the patients who experienced a postoperative epidural hematoma did not experience any significant improvement in health-related quality-of-life metrics as a result of the index procedure at final follow-up evaluation., Conclusion: This is the largest series to date to analyze the incidence of an epidural hematoma following cervical spine surgery, and this study suggest that an epidural hematoma occurs in approximately 1 out of 1000 cervical spine surgeries. Prompt diagnosis and treatment may improve the chance of making a complete neurologic recovery, but patients who develop this complication do not show improvements in the health-related quality-of-life measurements., 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: Gregory D. Schroeder reports grants from AOSpine North America during the conduct of the study, other from AOSpine, grants from Medtronic, outside the submitted work; Alan S. Hilibrand reports grants from AOSpine North America during the conduct of the study, other from Amedica, Vertiflex, Benvenue, Lifespine, Paradigm Spine, PSD, Spinal Ventures, outside the submitted work, and in addition, Dr. Hilibrand has a patent Aesculap, Amedica, Biomet, Stryker, Alphatec, with royalties paid; David E. Fish reports grants from AOSpine North America during the conduct of the study; Jeffrey C. Wang reports grants from AOSpine North America during the conduct of the study; Jeffrey L. Gum reports grants from AOSpine North America during the conduct of the study, personal fees from Medtronic, Alphatec, Stryker, LifeSpine, Acuity, Pacira, PAKmed, Gerson Lehrman Group, personal fees from OREF, AOSpine, personal fees from Acuity, other from Medtronic, personal fees from MiMedx, Pacira Pharmaceuticals, Alphatec, grants from Fischer Owen Fund, nonfinancial support from American Journal of Orthopaedics, nonfinancial support from American Journal of Orthopaedics, The Spine Journal, outside the submitted work; Zachary A. Smith reports grants from AOSpine North America during the conduct of the study; Wellington K. Hsu reports grants from AOSpine North America during the conduct of the study, personal fees from Medtronic, personal fees from Stryker, personal fees from Bacterin, personal fees from Graftys, personal fees from Ceramtec, personal fees from Relievant, personal fees from Bioventus, personal fees from Globus, personal fees from SpineSmith, outside the submitted work; Ziya L. Gokaslan reports grants from AOSpine North America during the conduct of the study, grants from AOSpine North America, personal fees from AO Foundation, grants from AOSpine, outside the submitted work; Robert E. Isaacs reports grants from AOSpine North America during the conduct of the study, grants and personal fees from NuVasive, Inc., personal fees from Association for Collaborative Spine research, outside the submitted work; Thomas E. Mroz reports other from AOSpine, grants from AOSpine North America during the conduct of the study; personal fees from Stryker, personal fees from Ceramtec, other from Pearl Diver, outside the submitted work; Ahmad Nassr reports grants from AOSpine North America during the conduct of the study; Michael G. Fehlings reports grants from AOSpine North America during the conduct of the study; Zorica Buser reports grants from AOSpine North America during the conduct of the study; Peter I. Cha reports grants from AOSpine North America during the conduct of the study; Erica L. Gee reports grants from AOSpine North America during the conduct of the study; Elizabeth L. Lord reports grants from AOSpine North America during the conduct of the study; Erik N. Mayer reports grants from AOSpine North America during the conduct of the study; Owen J. McBride reports grants from AOSpine North America during the conduct of the study; Emily C. Nguyen reports grants from AOSpine North America during the conduct of the study; P. Justin Tortolani reports grants from AOSpine North America during the conduct of the study, other from Globus Medical, grants from Spineology, other from Innovasis, outside the submitted work, and in addition, Dr. Tortolani has a patent Globus with royalties paid; D. Alex Stroh reports grants from AOSpine North America, during the conduct of the study; and K. Daniel Riew reports personal fees from AOSpine International, other from Global Spine Journal, other from Spine Journal, other from Neurosurgery, personal fees from Multiple Entities for defense, plantiff, grants from AOSpine, grants from Cerapedics, grants from Medtronic, personal fees from AOSpine, personal fees from NASS, personal fees from Biomet, personal fees from Medtronic, nonfinancial support from Broadwater, outside the submitted work; Paul M. Arnold reports grants from AOSpine North America during the conduct of the study; other from Z-Plasty, other from Medtronic Sofamore Danek, other from Stryker Spine, other from FzioMed, other from AOSpine North America, other from Life Spine, other from Integra Life, other from Spine Wave, other from MIEMS, other from Cerapedics, other from AOSpine North America, outside the submitted work; Rick C. Sasso reports grants from AOSpine North America during the conduct of the study; personal fees from medtronic, grants from medtronic, grants from K2, outside the submitted work; Mohamad Bydon reports grants from AOSpine North America during the conduct of the study; Dhananjay Chatterjee reports grants from AOSpine North America during the conduct of the study; Allison K. Roe reports grants from AOSpine North America during the conduct of the study; D. Alex Stroh reports grants from AOSpine North America during the conduct of the study; Marisa Y. Yanez reports grants from AOSpine North America during the conduct of the study.

Study Design: Multicenter retrospective case series., Objective: To determine the rate of thoracic duct injury during cervical spine operations., Methods: A retrospective case series study was conducted among 21 high-volume surgical centers to identify instances of thoracic duct injury during anterior cervical spine surgery. Staff at each center abstracted data for each identified case into case report forms. All case report forms were collected by the AOSpine North America Clinical Research Network Methodological Core for data processing, cleaning, and analysis., Results: Of a total of 9591 patients reviewed that underwent cervical spine surgery, 2 (0.02%) incurred iatrogenic injury to the thoracic duct. Both patients underwent a left-sided anterior cervical discectomy and fusion. The interruption of the thoracic duct was addressed intraoperatively in one patient with no residual postoperative effects. The second individual developed a chylous fluid collection approximately 2 months after the operation that required drainage via needle aspiration., Conclusions: Damage to the thoracic duct during cervical spine surgery is a relatively rare occurrence. Rapid identification of the disruption of this lymphatic vessel is critical to minimize deleterious effects of this complication., 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: Adeeb Derakhshan reports grants from AOSpine North America during the conduct of the study; Michael P. Steinmetz reports grants from AOSpine North America during the conduct of the study; Gabriel A. Smith reports grants from AOSpine North America during the conduct of the study; Ziya Gokaslan reports grants from AOSpine North America, personal fees from AO Foundation, grants from AOSpine, outside the submitted work; Michael G. Fehlings reports grants from AOSpine North America during the conduct of the study; K. Daniel Riew reports personal fees from AOSpine International, other from Global Spine Journal, other from Spine Journal, other from Neurosurgery, personal fees from Multiple Entities for defense, plantiff, grants from AOSpine, grants from Cerapedics, grants from Medtronic, personal fees from AOSpine, personal fees from NASS, personal fees from Biomet, personal fees from Medtronic, nonfinancial support from Broadwater, outside the submitted work; Thomas E. Mroz reports other from AOSpine during the conduct of the study, personal fees from Stryker, personal fees from Ceramtec, other from Pearl Diver, outside the submitted work; Daniel Lubelski reports grants from AOSpine North America during the conduct of the study; Mark Corriveau, reports grants from AOSpine North America during the conduct of the study; Sungho Lee, reports grants from AOSpine North America during the conduct of the study; Jonathan R. Pace, reports grants from AOSpine North America during the conduct of the study; Mohamad Bydon, reports grants from AOSpine North America during the conduct of the study; Paul M. Arnold reports grants from AOSpine North America during the conduct of the study; other from Z-Plasty, other from Medtronic Sofamore Danek, other from Stryker Spine, other from FzioMed, other from AOSpine North America, other from Life Spine, other from Integra Life, other from Spine Wave, other from MIEMS, other from Cerapedics, other from AOSpine North America, outside the submitted work.

Study Design: This study was a retrospective, multicenter cohort study., Objectives: Rare complications of cervical spine surgery are inherently difficult to investigate. Pseudomeningocoele (PMC), an abnormal collection of cerebrospinal fluid that communicates with the subarachnoid space, is one such complication. In order to evaluate and better understand the incidence, presentation, treatment, and outcome of PMC following cervical spine surgery, we conducted a multicenter study to pool our collective experience., Methods: This study was a retrospective, multicenter cohort study of patients who underwent cervical spine surgery at any level(s) from C2 to C7, inclusive; were over 18 years of age; and experienced a postoperative PMC., Results: Thirteen patients (0.08%) developed a postoperative PMC, 6 (46.2%) of whom were female. They had an average age of 48.2 years and stayed in hospital a mean of 11.2 days. Three patients were current smokers, 3 previous smokers, 5 had never smoked, and 2 had unknown smoking status. The majority, 10 (76.9%), were associated with posterior surgery, whereas 3 (23.1%) occurred after an anterior procedure. Myelopathy was the most common indication for operations that were complicated by PMC (46%). Seven patients (53%) required a surgical procedure to address the PMC, whereas the remaining 6 were treated conservatively. All PMCs ultimately resolved or were successfully treated with no residual effects., Conclusions: PMC is a rare complication of cervical surgery with an incidence of less than 0.1%. They prolong hospital stay. PMCs occurred more frequently in association with posterior approaches. Approximately half of PMCs required surgery and all ultimately resolved without residual neurologic or other long-term effects., 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: Tamir Ailon reports grants from AOSpine North America, during the conduct of the study; Justin S. Smith reports grants from AOSpine North America during the conduct of the study, personal fees from Biomet, personal fees from Nuvasive, personal fees from Cerapedics, personal fees from K2M, personal fees and other from DePuy, personal fees from Medtronic, outside the submitted work; Zachary A. Smith reports grants from AOSpine North America during the conduct of the study; Wellington K. Hsu reports grants from AOSpine North America during the conduct of the study, personal fees from Medtronic, personal fees from Stryker, personal fees from Bacterin, personal fees from Graftys, personal fees from Ceramtec, personal fees from Relievant, personal fees from Bioventus, personal fees from Globus, personal fees from SpineSmith, outside the submitted work; Michael G. Fehlings reports grants from AOSpine North America during the conduct of the study; David E. Fish reports grants from AOSpine North America during the conduct of the study; Jeffrey C. Wang reports grants from AOSpine North America during the conduct of the study; Alan S. Hilibrand reports grants from AOSpine North America during the conduct of the study, other from Amedica, Vertiflex, Benvenue, Lifespine, Paradigm Spine, PSD, Spinal Ventures, outside the submitted work, and in addition, Dr. Hilibrand has a patent Aesculap, Amedica, Biomet, Stryker, Alphatec, with royalties paid; Praveen V. Mummaneni reports grants from AOSpine North America during the conduct of the study, other from Depuy Spine, grants and other from AOSpine, other from Globus, other from Springer Publishers, other from Thieme Publishers, other from Taylor and Francis Publishers, other from Spincity/ISD, outside the submitted work; Dean Chou reports grants from AOSpine North America during the conduct of the study, other from Globus, other from Medtronic, other from Orthofix, outside the submitted work; Vincent C. Traynelis reports grants from AOSpine North America during the conduct of the study, and Medtronic - Royalties and Consultant Globus - Institutional Fellowship Support; Thomas E. Mroz reports other from AO Spine, grants from AOSpine North America during the conduct of the study, personal fees from Stryker, personal fees from Ceramtec, other from Pearl Diver, outside the submitted work; Zorica Buser reports grants from AOSpine North America during the conduct of the study; Elizabeth L. Lord reports grants from AOSpine North America during the conduct of the study; Eric M. Massicotte reports grants from AOSpine North America during the conduct of the study, grants from Medtronic, Depuy-Synthes Spine Canada, personal fees from Watermark consulting, grants from AOSpine North America, nonfinancial support from AOSpine North America, outside the submitted work; Arjun S. Sebastian reports grants from AOSpine North America during the conduct of the study; Khoi D. Than reports grants from AOSpine North America during the conduct of the study; Michael P. Steinmetz reports grants from AOSpine North America during the conduct of the study; Gabriel A. Smith reports grants from AOSpine North America during the conduct of the study; Jonathan Pace reports grants from AOSpine North America during the conduct of the study; K. Daniel Riew reports personal fees from AOSpine International, other from Global Spine Journal, other from Spine Journal, other from Neurosurgery, personal fees from Multiple Entities for defense, plantiff, grants from AOSpine, grants from Cerapedics, grants from Medtronic, personal fees from AOSpine, personal fees from NASS, personal fees from Biomet, personal fees from Medtronic, nonfinancial support from Broadwater, outside the submitted work; and Christopher Shaffrey reports grants from AOSpine North America during the conduct of the study, personal fees from Biomet, personal fees from Medtronic, from Nuvasive, personal fees from K2M, personal fees from Stryker, outside the submitted work, and Editorial Board Spine, Spinal Deformity and Neurosurgery; Hani R. Malone reports grants from AOSpine North America during the conduct of the study; Adam S. Kanter reports grants from AOSpine North America during the conduct of the study; Samuel K. Cho reports grants from AOSpine North America during the conduct of the study; grants from OREF, personal fees from Stryker, personal fees from Medtronic, personal fees from DePuy Synthes, outside the submitted work; Ra'Kerry K. Rahman reports grants from AOSpine North America during the conduct of the study; in addition, Dr. Rahman has a patent Deformity System & Pedicle Screws pending. Paul M. Arnold reports grants from AOSpine North America during the conduct of the study; other from Z-Plasty, other from Medtronic Sofamore Danek, other from Stryker Spine, other from FzioMed, other from AOSpine North America, other from Life Spine, other from Integra Life, other from Spine Wave, other from MIEMS, other from Cerapedics, other from AOSpine North America, outside the submitted work.

Study Design: A retrospective multicenter case-series study; case report and review of the literature., Objective: The anatomy and function of the superior laryngeal nerve (SLN) are well described; however, the consequences of SLN injury remain variable and poorly defined. The prevalence of SLN injury as a consequence of cervical spine surgery is difficult to discern as its clinical manifestations are often inconstant and frequently of a subclinical degree. A multicenter study was performed to better delineate the risk factors, prevalence, and outcomes of SLN injury., Methods: A retrospective multicenter case-series study involving 21 high-volume surgical centers from the AO Spine North America Clinical Research Network. Medical records for 17 625 patients who received subaxial cervical spine surgery from 2005 to 2011 were reviewed to identify occurrence of 21 predefined treatment complications. Descriptive statistics were provided for baseline patient characteristics. A retrospective review of the neurosurgical literature on SLN injury was also performed., Results: A total of 8887 patients who underwent anterior cervical spine surgery at the participating institutions were screened, and 1 case of SLN palsy was identified. The prevalence ranged from 0% to 1.25% across all centers. The patient identified underwent a C4 corpectomy. The SLN injury was identified after the patient demonstrated difficulty swallowing postoperatively. He underwent placement of a percutaneous gastrostomy tube and his SLN palsy resolved by 6 weeks., Conclusions: This multicenter study demonstrates that identification of SLN injury occurs very infrequently. Symptomatic SLN injury is an exceedingly rare complication of anterior cervical spine surgery. The SLN is particularly vulnerable when exposing the more rostral levels of the cervical spine. Careful dissection and retraction of the longus coli may decrease the risk of SLN injury during anterior cervical surgery., 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: Zachary J. Tempel reports grants from AOSpine North America during the conduct of the study; Justin S. Smith reports grants from AOSpine North America during the conduct of the study, personal fees from Biomet, personal fees from Nuvasive, personal fees from Cerapedics, personal fees from K2M, personal fees and other from DePuy, personal fees from Medtronic, outside the submitted work; Christopher Shaffrey reports grants from AOSpine North America during the conduct of the study, personal fees from Biomet, personal fees from Medtronic, from Nuvasive, personal fees from K2M, personal fees from Stryker, outside the submitted work, and Editorial Board Spine, Spinal Deformity and Neurosurgery; Paul M. Arnold reports grants from AOSpine North America, during the conduct of the study; other from Z-Plasty, other from Medtronic Sofamore Danek, other from Stryker Spine, other from FzioMed, other from AOSpine North America, other from Life Spine, other from Integra Life, other from Spine Wave, other from MIEMS, other from Cerapedics, other from AOSpine North America, outside the submitted work; Michael G. Fehlings reports grants from AOSpine North America during the conduct of the study; Thomas E. Mroz reports other from AOSpine, during the conduct of the study, personal fees from Stryker, personal fees from Ceramtec, other from Pearl Diver, outside the submitted work; and K. Daniel Riew reports personal fees from AOSpine International, other from Global Spine Journal, other from Spine Journal, other from Neurosurgery, personal fees from Multiple Entities for defense, plantiff , grants from AOSpine, grants from Cerapedics, grants from Medtronic, personal fees from AOSpine, personal fees from NASS, personal fees from Biomet, personal fees from Medtronic, nonfinancial support from Broadwater, outside the submitted work; Adam S. Kanter reports grants from AOSpine North America, during the conduct of the study.

Study Design: A multicenter, retrospective case series., Objective: In the past several years, screw fixation of the cervical spine has become commonplace. For the most part, this is a safe, low-risk procedure. While rare, screw backout or misplaced screws can lead to morbidity and increased costs. We report our experiences with this uncommon complication., Methods: A multicenter, retrospective case series was undertaken at 23 institutions in the United States. Patients were included who underwent cervical spine surgery from January 1, 2005, to December 31, 2011, and had misplacement of screws requiring reoperation. Institutional review board approval was obtained at all participating institutions, and detailed records were sent to a central data center., Results: A total of 12 903 patients met the inclusion criteria and were analyzed. There were 11 instances of screw backout requiring reoperation, for an incidence of 0.085%. There were 7 posterior procedures. Importantly, there were no changes in the health-related quality-of-life metrics due to this complication. There were no new neurologic deficits; a patient most often presented with pain, and misplacement was diagnosed on plain X-ray or computed tomography scan. The most common location for screw backout was C6 (36%)., Conclusions: This study represents the largest series to tabulate the incidence of misplacement of screws following cervical spine surgery, which led to revision procedures. The data suggest this is a rare event, despite the widespread use of cervical fixation. Patients suffering this complication can require revision, but do not usually suffer neurologic sequelae. These patients have increased cost of care. Meticulous technique and thorough knowledge of the relevant anatomy are the best means of preventing this complication., 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: Jeremy C. Peterson reports grants from AOSpine North America during the conduct of the study; Wellington K. Hsu reports grants from AOSpine North America during the conduct of the study, personal fees from Medtronic, personal fees from Stryker, personal fees from Bacterin, personal fees from Graftys, personal fees from Ceramtec, personal fees from Relievant, personal fees from Bioventus, personal fees from Globus, personal fees from SpineSmith, outside the submitted work; Michael G. Fehlings reports grants from AOSpine North America during the conduct of the study; Robert A. Hart reports grants from AOSpine North America during the conduct of the study, other from CSRS, other from ISSLS, other from ISSG Exec Board, personal fees from Depuy Synthes, personal fees from Globus, personal fees from Medtronic, other from Evans, Craven & Lackie, other from Benson, Bertoldo, Baker, & Carter, personal fees from Seaspine, personal fees from Depuy Synthes, other from Spine Connect, personal fees from Depuy Synthes, outside the submitted work; Alan S. Hilibrand reports grants from AOSpine North America during the conduct of the study, other from Amedica, Vertiflex, Benvenue, Lifespine, Paradigm Spine, PSD, Spinal Ventures, outside the submitted work, and in addition, Dr. Hilibrand has a patent Aesculap, Amedica, Biomet, Stryker, Alphatec, with royalties paid; Tony Tannoury reports grants from AOSpine North America during the conduct of the study; Thomas E. Mroz reports other from AO Spine during the conduct of the study, personal fees from Stryker, personal fees from Ceramtec, other from Pearl Diver, outside the submitted work; Bradford L. Currier reports grants from AOSpine North America during the conduct of the study, personal fees from DePuy Spine, personal fees from Stryker Spine, personal fees from Zimmer Spine, other from Zimmer Spine, other from Tenex, other from Spinology, other from LSRS, other from AOSNA, outside the submitted work; Jeremy L. Fogelson reports grants from AOSpine North America during the conduct of the study and Previous Consultant for one day to Depuy-Synthes March 2014; Bruce C. Jobse reports grants from AOSpine North America during the conduct of the study; Eric M. Massicotte reports grants from AOSpine North America during the conduct of the study, grants from Medtronic, Depuy-Synthes Spine Canada, personal fees from Watermark Consulting, grants from AOSpine North America, nonfinancial support from AOSpine North America, outside the submitted work; and K. Daniel Riew reports personal fees from AOSpine International, other from Global Spine Journal, other from Spine Journal, other from Neurosurgery, personal fees from Multiple Entities for defense, plaintiff, grants from AOSpine, grants from Cerapedics, grants from Medtronic, personal fees from AOSpine, personal fees from NASS, personal fees from Biomet, personal fees from Medtronic, nonfinancial support from Broadwater, outside the submitted work; Paul M. Arnold reports grants from AOSpine North America during the conduct of the study; other from Z-Plasty, other from Medtronic Sofamore Danek, other from Stryker Spine, other from FzioMed, other from AOSpine North America, other from Life Spine, other from Integra Life, other from Spine Wave, other from MIEMS, other from Cerapedics, other from AOSpine North America, outside the submitted work; Zachary A. Smith reports grants from AOSpine North America during the conduct of the study; Ahmad Nassr reports grants from AOSpine North America during the conduct of the study; Ra’Kerry K. Rahman reports grants from AOSpine North America during the conduct of the study; in addition, Dr. Rahman has a patent Deformity System & Pedicle Screws pending. Chadi A. Tannoury reports grants from AOSpine North America during the conduct of the study; Anthony F. De Giacomo Dr. De Giacomo reports grants from AOSpine North America during the conduct of the study.

Study Design: A multicenter retrospective case series., Objective: Horner's syndrome is a known complication of anterior cervical spinal surgery, but it is rarely encountered in clinical practice. To better understand the incidence, risks, and neurologic outcomes associated with Horner's syndrome, a multicenter study was performed to review a large collective experience with this rare complication., Methods: We conducted a retrospective multicenter case series study involving 21 high-volume surgical centers from the AOSpine North America Clinical Research Network. Medical records for 17 625 patients who received subaxial cervical spine surgery from 2005 to 2011 were reviewed to identify occurrence of 21 predefined treatment complications. Descriptive statistics were provided for baseline patient characteristics. Paired t test was used to analyze changes in clinical outcomes at follow-up compared to preoperative status., Results: In total, 8887 patients who underwent anterior cervical spine surgery at the participating institutions were screened. Postoperative Horner's syndrome was identified in 5 (0.06%) patients. All patients experienced the complication following anterior cervical discectomy and fusion. The sympathetic trunk appeared to be more vulnerable when operating on midcervical levels (C5, C6), and most patients experienced at least a partial recovery without further treatment., Conclusions: This collective experience suggests that Horner's syndrome is an exceedingly rare complication following anterior cervical spine surgery. Injury to the sympathetic trunk may be limited by maintaining a midline surgical trajectory when possible, and performing careful dissection and retraction of the longus colli muscle when lateral exposure is necessary, especially at caudal cervical levels., 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: Vincent C. Traynelis reports grants from AOSpine North America during the conduct of the study, and Medtronic - Royalties, Consultant Globus - Institutional Fellowship Support; Zachary A. Smith reports grants from AOSpine North America during the conduct of the study; Wellington K. Hsu reports grants from AOSpine North America during the conduct of the study, personal fees from Medtronic, personal fees from Stryker, personal fees from Bacterin, personal fees from Graftys, personal fees from Ceramtec, personal fees from Relievant, personal fees from Bioventus, personal fees from Globus, personal fees from SpineSmith, outside the submitted work; Sheeraz A. Qureshi reports grants from AOSpine North America during the conduct of the study, and is a consultant and receives royalties from Stryker Spine, Biomet Spine, and RTI; Evan O. Baird reports grants from AOSpine North America during the conduct of the study; Robert E. Isaacs reports grants from AOSpine North America during the conduct of the study, grants and personal fees from NuVasive, Inc., personal fees from Association for Collaborative Spine research, outside the submitted work; Galina Polevaya reports grants from AOSpine North America during the conduct of the study; Justin S. Smith reports grants from AOSpine North America during the conduct of the study, personal fees from Biomet, personal fees from Nuvasive, personal fees from Cerapedics, personal fees from K2M, personal fees and other from DePuy, personal fees from Medtronic, outside the submitted work; Christopher Shaffrey reports grants from AOSpine North America during the conduct of the study, personal fees from Biomet, personal fees from Medtronic, from Nuvasive, personal fees from K2M, personal fees from Stryker, outside the submitted work, and Editorial Board Spine, Spinal Deformity and Neurosurgery; P. Justin Tortolani reports grants from AOSpine North America during the conduct of the study, other from Globus Medical, grants from Spineology, other from Innovasis, outside the submitted work, and in addition, Dr. Tortolani has a patent Globus with royalties paid; D. Alex Stroh reports grants from AOSpine North America during the conduct of the study; Michael G. Fehlings reports grants from AOSpine North America during the conduct of the study; Thomas E. Mroz reports other from AOSpine, grants from AOSpine North America, during the conduct of the study, personal fees from Stryker, personal fees from Ceramtec, other from Pearl Diver, outside the submitted work; and K. Daniel Riew reports personal fees from AOSpine International, other from Global Spine Journal, other from Spine Journal, other from Neurosurgery, personal fees from Multiple Entities for defense, plantiff , grants from AOSpine, grants from Cerapedics, grants from Medtronic, personal fees from AOSpine, personal fees from NASS, personal fees from Biomet, personal fees from Medtronic, nonfinancial support from Broadwater, outside the submitted work; Hani R. Malone reports grants from AOSpine North America during the conduct of the study; Adam S. Kanter reports grants from AOSpine North America during the conduct of the study; Samuel K. Cho reports grants from AOSpine North America during the conduct of the study; grants from OREF, personal fees from Stryker, personal fees from Medtronic, personal fees from DePuy Synthes, outside the submitted work; Ra'Kerry K. Rahman reports grants from AOSpine North America during the conduct of the study; in addition, Dr. Rahman has a patent Deformity System & Pedicle Screws pending. Paul M. Arnold reports grants from AOSpine North America during the conduct of the study; other from Z-Plasty, other from Medtronic Sofamore Danek, other from Stryker Spine, other from FzioMed, other from AOSpine North America, other from Life Spine, other from Integra Life, other from Spine Wave, other from MIEMS, other from Cerapedics, other from AOSpine North America, outside the submitted work.

Study Design: A multicenter, retrospective review of C5 palsy after cervical spine surgery., Objective: Postoperative C5 palsy is a known complication of cervical decompressive spinal surgery. The goal of this study was to review the incidence, patient characteristics, and outcome of C5 palsy in patients undergoing cervical spine surgery., Methods: We conducted a multicenter, retrospective review of 13 946 patients across 21 centers who received cervical spine surgery (levels C2 to C7) between January 1, 2005, and December 31, 2011, inclusive. P values were calculated using 2-sample t test for continuous variables and χ 2 tests or Fisher exact tests for categorical variables., Results: Of the 13 946 cases reviewed, 59 patients experienced a postoperative C5 palsy. The incidence rate across the 21 sites ranged from 0% to 2.5%. At most recent follow-up, 32 patients reported complete resolution of symptoms (54.2%), 15 had symptoms resolve with residual effects (25.4%), 10 patients did not recover (17.0%), and 2 were lost to follow-up (3.4%)., Conclusion: C5 palsy occurred in all surgical approaches and across a variety of diagnoses. The majority of patients had full recovery or recovery with residual effects. This study represents the largest series of North American patients reviewed to date., 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: Sara E. Thompson reports grants from AOSpine North America during the conduct of the study; Zachary A. Smith reports grants from AOSpine North America during the conduct of the study; Wellington K. Hsu reports grants from AOSpine North America during the conduct of the study, personal fees from Medtronic, personal fees from Stryker, personal fees from Bacterin, personal fees from Graftys, personal fees from Ceramtec, personal fees from Relievant, personal fees from Bioventus, personal fees from Globus, personal fees from SpineSmith, outside the submitted work; Ahmad Nassr reports grants from AOSpine North America during the conduct of the study; Thomas E. Mroz reports other from AOSpine, grants from AOSpine North America during the conduct of the study, personal fees from Stryker, personal fees from Ceramtec, other from Pearl Diver, outside the submitted work; David E. Fish reports grants from AOSpine North America during the conduct of the study; Jeffrey C. Wang reports grants from AOSpine North America during the conduct of the study; Michael G. Fehlings reports grants from AOSpine North America during the conduct of the study; Chadi A. Tannoury reports grants from AOSpine North America during the conduct of the study; Tony Tannoury reports grants from AOSpine North America during the conduct of the study; P. Justin Tortolani reports grants from AOSpine North America during the conduct of the study, other from Globus Medical, grants from Spineology, other from Innovasis, outside the submitted work, and in addition, Dr. Tortolani has a patent Globus with royalties paid; Vincent C. Traynelis reports grants from AOSpine North America during the conduct of the study, and Medtronic – Royalties, Consultant Globus – Institutional Fellowship Support; Ziya Gokaslan reports grants from AOSpine North America during the conduct of the study, grants from AOSpine North America, personal fees from AO Foundation, grants from AOSpine, outside the submitted work; Alan S. Hilibrand reports grants from AOSpine North America during the conduct of the study, other from Amedica, Vertiflex, Benvenue, Lifespine, Paradigm Spine, PSD, Spinal Ventures, outside the submitted work, and in addition, Dr. Hilibrand has a patent Aesculap, Amedica, Biomet, Stryker, Alphatec, with royalties paid; Robert E. Isaacs reports grants from AOSpine North America during the conduct of the study, grants and personal fees from NuVasive, Inc., personal fees from Association for Collaborative Spine research, outside the submitted work; Praveen V. Mummaneni reports grants from AOSpine North America during the conduct of the study, other from Deputy Spine, grants and other from AOSpine, other from Globus, other from Springer Publishers, other from Thieme Publishers, other from Taylor and Francis Publishers, other from Spincity/ISD, outside the submitted work; Dean Chou reports grants from AOSpine North America during the conduct of the study, other from Globus, other from Medtronic, other from Orthofix, outside the submitted work; Sheeraz A. Qureshi reports grants from AOSpine North America during the conduct of the study, and is a consultant and receives royalties from Stryker Spine, Biomet Spine, and RTI; Evan O. Baird reports grants from AOSpine North America during the conduct of the study; Zorica Buser reports grants from AOSpine North America during the conduct of the study; Michelle J. Clarke reports grants from AOSpine North America during the conduct of the study; Adeeb Derakhshan reports grants from AOSpine North America during the conduct of the study; Elizabeth L. Lord reports grants from AOSpine North America during the conduct of the study; Eric M. Massicotte reports grants from AOSpine North America during the conduct of the study, grants from Medtronic, Depuy-Synthes Spine Canada, personal fees from Watermark consulting, grants from AOSpine North America, nonfinancial support from AOSpine North America, outside the submitted work; Michael P. Steinmetz reports grants from AOSpine North America during the conduct of the study; Jonathan Pace reports grants from AOSpine North America during the conduct of the study; Peter I. Cha reports grants from AOSpine North America during the conduct of the study; Erica L. Gee reports grants from AOSpine North America during the conduct of the study; D. Alex Stroh reports grants from AOSpine North America during the conduct of the study; Khoi D. Than reports grants from AOSpine North America during the conduct of the study; and K. Daniel Riew reports personal fees from AOSpine International, other from Global Spine Journal, other from Spine Journal, other from Neurosurgery, personal fees from Multiple Entities for defense, plantiff, grants from AOSpine, grants from Cerapedics, grants from Medtronic, personal fees from AOSpine, personal fees from NASS, personal fees from Biomet, personal fees from Medtronic, nonfinancial support from Broadwater, outside the submitted work; Samuel K. Cho reports grants from AOSpine North America during the conduct of the study; grants from OREF, personal fees from Stryker, from Medtronic, personal fees from DePuy Synthes, outside the submitted work; Rick C. Sasso reports grants from AOSpine North America during the conduct of the study; personal fees from medtronic, grants from medtronic, grants from K2, outside the submitted work; Paul M. Arnold reports grants from AOSpine North America during the conduct of the study; other from Z-Plasty, other from Medtronic Sofamore Danek, other from Stryker Spine, other from FzioMed, other from AOSpine North America, other from Life Spine, other from Integra Life, other from Spine Wave, other from MIEMS, other from Cerapedics, other from AOSpine North America, outside the submitted work; Mohamad Bydon reports grants from AOSpine North America during the conduct of the study; Anthony F. De Giacomo reports grants from AOSpine North America during the conduct of the study; Bruce Jobse reports grants from AOSpine North America during the conduct of the study; Daniel Lubelski reports grants from AOSpine North America during the conduct of the study; Mark Corriveau reports grants from AOSNA during the conduct of the study; Sungho Lee reports grants from AOSpine North America during the conduct of the study; Dhananjay Chatterjee reports grants from AOSpine North America during the conduct of the study; Erik N. Mayer reports grants from AOSpine North America during the conduct of the study; Owen J. McBride reports grants from AOSpine North America during the conduct of the study; Allison K. Roe reports grants from AOSpine North America during the conduct of the study; Marisa Y. Yanez reports grants from AOSpine North America during the conduct of the study.