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STUDY DESIGN Retrospective descriptive study. OBJECTIVE To create topographical maps of occipital bone thickness and venous sinus (VS) presence to assess the risks of screw insertion in four commercially available occipital plates. SUMMARY OF BACKGROUND DATA Craniocervical junction instability and deformity are serious pathological conditions that require posterior fixation of the occipital bone to the cervical vertebrae. Insertion of occipital bone screws requires evaluation of both occipital bone thickness for effective internal fixation and intracranial venous sinus presence for vascular injury prevention. Despite the surgical risks, there is a paucity of research on safe screw placement. METHODS We created a matrix of 231 standardized measurement points to analyze the occipital bone thickness and venous sinus presence in cervical spine CT angiograms. These measurements were used to create topographical maps of occipital bone thickness and likelihood of venous sinus presence, which we then compared to the screw hole configurations of four occipital plates. RESULTS 100 patients were assessed. Maximum occipital bone thickness of 13.9 ± 3.3 mm was midline in the occipital bone, 45 mm from the foramen magnum, around the external occipital protuberance (EOP). Regions with thicknesses >8 mm were 2 cm lateral to the EOP at the level of the superior nuchal line and 2.5 cm inferior to the EOP. The area with the highest VS presence rate was around the EOP and the superior nuchal line. The right transverse VS was more prominent in both sexes. CONCLUSION There is a limited area of the occipital bone with thicknesses for enough screw purchase. Previous studies have shown 8 mm as the minimum screw length to reduce the risk of implant failure. In our analysis, only "T"-shaped plates had configurations with thicknesses >8 mm for each screw hole. For every screw hole in the analyzed occipital plates, there was a possibility of venous sinus presence ranging from 8-33%.Level of Evidence: 5.

Study design Retrospective observational study. Objectives To investigate the spinal cord safety margins for C2 instrumentation. Summary of background data Intraoperative spinal cord injury during C2 spine surgery is a rare, but potentially life-threatening complication. Pre-operative planning for C2 instrumentation mainly focuses on C2 pedicle bony dimensions on CT and the vertebral artery location and few studies have evaluated C2 spinal cord safety margins. Methods We measured two distances in C2 bilaterally: 1) C2 pedicle to dura distance (P-D), defined as a transverse line that measured the shortest distance between the medial wall of the C2 pedicle and the dural sac, 2) C2 pedicle to spinal cord (P-SC), defined as a transverse line that measured the shortest distance between the medial wall of the C2 pedicle and spinal cord. We defined the distances above 4 mm as safe for instrumentation. Result A total of 146 patients (mean age 71.2, 50.7% female) were included. The average distances were 5.5 mm for C2 left P-D, 5.9 mm for C2 right P-D, 10.1 mm for C2 left P-SC and 10.6 mm for C2 right P-SC. Twenty eight (21.4%) patients had C2 P-D distances under 4 mm and out of those 2 (7%) patients had distances under 2 mm. There were more female patients with C2 P-D distances under 4 mm compared to males. No patient had C2 P-SC distances under 4 mm. Conclusion We demonstrated that around 20% of patients had C2 P-D distance below 4 mm, but no patient had C2 P-SC distance less than 4 mm. Since a lateral misplacement can lead to a potentially fatal vertebral artery injury, medial screw trajectory is recommended for C2 pedicle instrumentation with consideration of these safety margins.Level of Evidence: 3.

Retrospective cohort analysis.To elucidate trends in the utilization of intraoperative neuromonitoring (IONM) during elective anterior cervical decompression and fusion (ACDF) procedures in New York State using the Statewide Planning and Research Cooperative System (SPARCS) and to determine if utilization of IONM resulted in a reduction in postoperative neurologic deficits.IONM has been available to spinal surgeons for several decades. It has become increasingly prevalent in all facets of spinal surgery including elective ACDF procedures. The utility of IONM for preventing neurologic deficit in elective spine procedures has recently been called into question.The SPARCS database was accessed to perform a retrospective cohort study comparing monitored versus unmonitored ACDF procedures between 2007 to 2018 as defined by International Classification of Disease-9 and 10 Procedural Coding System (ICD-9 PCS, ICD-10 PCS) codes. Patient demographics, medical history, surgical intervention, pertinent in-hospital events, and urban versus rural medical center (as defined by the US Office of Management and Budget) were recorded. Propensity-score-matched (PSM) comparisons were used to identify factors related to the utilization of IONM and risk factors for neurologic deficits following elective ACDF.A total of 70,838 (15,092 monitored [21.3%] and 55,746 [78.7%] unmonitored) patients' data were extracted. The utilization of IONM since 2007 has increased in a linear fashion from 0.9% of cases in 2007 to 36.7% by 2018. Overall, baseline characteristics of patients who were monitored during cases differed significantly from unmonitored patients in age, race/ethnicity, insurance type, presence of myelopathy or radiculopathy, and Charlson Comorbidity Index (CCI); however, only race/ethnicity was statistically significant when analyzed using PSM. When comparing urban and rural medical centers, there is a significant lag in adoption of the technology with no monitored cases in rural centers until 2012 with significant fluctuations in utilization compared to steadily increasing utilization among urban centers. During 2017-2018 reporting of neurologic deficit after surgery resembled literature-established norms. Pooled analysis of these years revealed that incidence of neurological complication occurred more frequently in monitored cases than unmonitored (3.0% vs. 1.4%, P0.001).The utility of IONM for elective ACDF remains uncertain; however, it continues to gain popularity for routine cases. For medical centers that lack similar resources to centers in more densely populated regions of New York State, reliable access to this technology is not a certainty. In our analysis of intraoperative neurological complications, it appears that IONM is not protective against neurologic injury.

Study design Longitudinal cohort. Objective The aims of this study were to measure concordance between patients' and surgeons' preoperative expectations of lumbar surgery, and determine which member of the dyad more closely predicted fulfillment of expectations, defined as patient-reported status postoperatively. Summary of background data Concordant patient-surgeon expectations reflect effective communication and should foster better outcomes. Methods Preoperatively patients and surgeons completed identical surveys measuring expectations for improvement in symptoms and physical/psychosocial function. Responses ranged from "complete improvement" to "do not have this expectation"; scores for each survey ranged from 0 to 100 (greatest expectations). Concordance between pairs of patient-surgeon scores was measured with the intraclass correlation coefficient (ICC). Postoperatively, fulfillment of expectations was measured from patient-reported amount of improvement received and was calculated as the proportion of patient-reported postoperative score relative to patient-reported preoperative score, and surgeon-reported preoperative score (range 0 [no expectations fulfilled] to >1.2 [expectations surpassed]). Clinical measures included patient-reported spine-related disability. Results For 402 patient-surgeon pairs, mean survey scores were 73 ± 19 (patients) and 57 ± 16 (surgeons); 84% of patients had higher scores than surgeons, mainly due to expecting complete improvement, whereas surgeons expected a lot/moderate/little improvement. The ICC for the entire sample was .31 (fair agreement); for subgroups, the greatest difference in ICC was for patients with more spine-related disability (ICC = .10, 95% confidence interval [CI]:0.00-0.23) versus less disability (ICC = .46, 95% CI: 0.34-0.56). 96% of patients were contacted ≥2.0 years postoperatively. Proportions of expectations fulfilled were 0.79 (0-3.00) (patients) and 1.01 (0-2.29) (surgeons). Thus patients were less likely to anticipate subsequent postoperative status (odds ratio [OR] 0.34, 95% CI 0.25-0.45) versus surgeons who were more likely to anticipate patient-reported postoperative status (OR 2.98, 95% CI: 2.22-4.00). Conclusion Concordance between patients' and surgeons' expectations was fair; due mostly to patients expecting complete improvement whereas surgeons expected a lot/moderate/little improvement. Compared to patients' expectations, surgeons' expectations more closely coincided with patient-reported fulfillment of expectations 2 years postoperatively.Level of Evidence: 1.

Study design Retrospective case series. Objective The aim of this study was to investigate the association of Modic type endplate changes with the risk of severe subsidence after standalone lateral lumbar interbody fusion (SA-LLIF). Summary of background data It has been reported that certain endplate radiolographic features are associated with higher regional bone mineral density (BMD) in the adjacent vertebrae in the lumbar spine. It remains unclear whether these changes have protective effects against osteoporotic complications such as cage subsidence after lumbar surgery. Methods We reviewed patients undergoing SA-LLIF from 2007 to 2016 with a follow-up >6 months. Cage subsidence was assessed utilizing the grading system by Marchi et al. As potential contributing factors for cage subsidence, we measured the endplate volumetric BMD (EP-vBMD) and the standard trabecular volumetric BMD measurement in the vertebral body. Modic changes (MC) on magnetic resonance imaging were measured as a qualitative factor for endplate condition. Univariate analysis and multivariate logistic regression analyses with a generalized mixed model were conducted. Results Two hundred six levels in 97 patients were included in the final analysis. Mean age (± SD) was 66.7 ± 10.7. Sisty-sdpercent of the patients were female. Severe subsidence was observed in 66 levels (32.0%). After adjusting for age, bone morphogenetic protein (BMP) use, and number of levels fused, the presence of MC type 2 was significantly associated with lower risk of severe subsidence (OR = 0.28 [0.09-0.88], P = 0.029). Whereas, EP-vBMD did not demonstrate a statistical significance (p = 0.600). Conclusion The presence of a Modic type 2 change was significantly associated with lower odds of severe subsidence after SA-LLIF. Nonetheless, this significant association was independent from regional EP-vBMD values. This finding suggests that microstructural and/or material property changes associated with Modic type 2 changes might have a protective effect in this patient population. Level of evidence 4.

STUDY DESIGN Retrospective database study. OBJECTIVE We sought to investigate trends and risk factors for new-onset anxiety and/or depression within 6 months after elective spine surgery. SUMMARY OF BACKGROUND DATA Surgery represents a stressful experience associated with a number of physiological and psychological consequences. A subset of patients develop clinically significant symptoms of new-onset anxiety or depression. However, the incidence of and risk factors for these adverse outcomes after spine surgery remain ill-defined. METHODS We performed a retrospective analysis including anterior cervical discectomy and fusion and posterior lumbar fusion cases from 2012 to 2015, utilizing the Truven MarketScan database. Primary outcomes were new-onset depression, new-onset anxiety, and new-onset depression and/or anxiety after surgery. Potential risk factors included patient demographics, comorbidities, hospital and procedural characteristics as well as perioperative opioid regimens. Multivariable logistic regression models measured associations between risk factors and outcomes. Odds ratios (OR) were reported and results with P

STUDY DESIGN Retrospective database study. OBJECTIVE We sought to identify trends in demographics, comorbidities, and postoperative complications among patients undergoing ACDF and PLF. SUMMARY OF BACKGROUND DATA As demand for anterior cervical discectomy and fusion (ACDF) and posterior lumbar fusion (PLF) surgery continues to increase, it is important to understand changes in the healthcare system and patient populations undergoing these procedures. METHODS We identified 220,520 ACDF and 151,547 PLF surgeries (2006-2016; Premier Healthcare database). Annual proportions or medians were calculated for patient and hospital characteristics, and (Elixhauser) comorbidities. Postoperative complications, including blood transfusions, cardiovascular, pulmonary, renal, or wound complications, hemorrhage, stroke, sepsis, thromboembolism, delirium, inpatient falls, and mortality, were reported per 1000 inpatient days. Trends were assessed by Cochran-Armitage tests and linear regression for binary and continuous variables, respectively. RESULTS The median age of patients undergoing ACDF and PLF increased significantly from 2006 to 2016 (50 to 57 yr and 58 to 61 yr, respectively; P

STUDY DESIGN Retrospective database analysis. OBJECTIVE To identify preoperative risk factors for emergency department (ED) visit and unplanned hospital readmission after primary anterior cervical discectomy and fusion (ACDF) at 30 and 90 days. SUMMARY OF BACKGROUND DATA Limited data exist to identify factors associated with ED visit or readmission after primary ACDF within the first 3 months following surgery. METHODS Patients undergoing ACDF from 2005 to 2012 were identified in the Statewide Planning and Research Cooperative System database. Multivariable regression models were created based on patient-level and surgical characteristics to identify independent risk factors for hospital revisit. RESULTS Of 41,813 patients identified, 2514 (6.0%) returned to the ED within 30 days of discharge. Risk factors included age 1, length of stay (LOS) greater than 1 day (OR 1.23), and fusion of > 2 levels (OR 1.17). Four thousand six hundred nine (11.0%) patients returned to the ED within 90 days. Risk factors mirrored those at 30 days. Patients having private insurance or those discharged to rehab were less likely to present to the ED. One thousand three hundred ninety-four (3.3%) patients were readmitted by 30 days. Risk factors included male sex, Medicare, or Medicaid insurance (OR 1.71 and 1.79 respectively), Charlson comorbidity index > 1, discharge to a skilled nursing facility (OR 2.90), infectious/pathologic (OR 3.296), or traumatic (OR 1.409) surgical indication, LOS > 1 day (OR 1.66), or in-hospital complication. 2223 (5.3%) patients were readmitted by 90 days. Risk factors mirrored those at 30 days. No differences in readmission were seen based on race or number of levels fused. Patients aged 18 to 34 were less likely to be readmitted versus patients older than 35. CONCLUSION Insurance status, comorbidities, and LOS consistently predicted an unplanned hospital visit at 30 and 90 days. Although nondegenerative surgical indications and in-hospital complications did not predict ED visits, these factors increased the risk for readmission. LEVEL OF EVIDENCE 3.

Longitudinal cohort.The aims of this study were to measure concordance between patients' and surgeons' preoperative expectations of lumbar surgery, and determine which member of the dyad more closely predicted fulfillment of expectations, defined as patient-reported status postoperatively.Concordant patient-surgeon expectations reflect effective communication and should foster better outcomes.Preoperatively patients and surgeons completed identical surveys measuring expectations for improvement in symptoms and physical/psychosocial function. Responses ranged from "complete improvement" to "do not have this expectation"; scores for each survey ranged from 0 to 100 (greatest expectations). Concordance between pairs of patient-surgeon scores was measured with the intraclass correlation coefficient (ICC). Postoperatively, fulfillment of expectations was measured from patient-reported amount of improvement received and was calculated as the proportion of patient-reported postoperative score relative to patient-reported preoperative score, and surgeon-reported preoperative score (range 0 [no expectations fulfilled] to1.2 [expectations surpassed]). Clinical measures included patient-reported spine-related disability.For 402 patient-surgeon pairs, mean survey scores were 73 ± 19 (patients) and 57 ± 16 (surgeons); 84% of patients had higher scores than surgeons, mainly due to expecting complete improvement, whereas surgeons expected a lot/moderate/little improvement. The ICC for the entire sample was .31 (fair agreement); for subgroups, the greatest difference in ICC was for patients with more spine-related disability (ICC = .10, 95% confidence interval [CI]:0.00-0.23) versus less disability (ICC = .46, 95% CI: 0.34-0.56). 96% of patients were contacted ≥2.0 years postoperatively. Proportions of expectations fulfilled were 0.79 (0-3.00) (patients) and 1.01 (0-2.29) (surgeons). Thus patients were less likely to anticipate subsequent postoperative status (odds ratio [OR] 0.34, 95% CI 0.25-0.45) versus surgeons who were more likely to anticipate patient-reported postoperative status (OR 2.98, 95% CI: 2.22-4.00).Concordance between patients' and surgeons' expectations was fair; due mostly to patients expecting complete improvement whereas surgeons expected a lot/moderate/little improvement. Compared to patients' expectations, surgeons' expectations more closely coincided with patient-reported fulfillment of expectations 2 years postoperatively.Level of Evidence: 1.

Retrospective case series.The aim of this study was to investigate the association of Modic type endplate changes with the risk of severe subsidence after standalone lateral lumbar interbody fusion (SA-LLIF).It has been reported that certain endplate radiolographic features are associated with higher regional bone mineral density (BMD) in the adjacent vertebrae in the lumbar spine. It remains unclear whether these changes have protective effects against osteoporotic complications such as cage subsidence after lumbar surgery.We reviewed patients undergoing SA-LLIF from 2007 to 2016 with a follow-up6 months. Cage subsidence was assessed utilizing the grading system by Marchi et al. As potential contributing factors for cage subsidence, we measured the endplate volumetric BMD (EP-vBMD) and the standard trabecular volumetric BMD measurement in the vertebral body. Modic changes (MC) on magnetic resonance imaging were measured as a qualitative factor for endplate condition. Univariate analysis and multivariate logistic regression analyses with a generalized mixed model were conducted.Two hundred six levels in 97 patients were included in the final analysis. Mean age (± SD) was 66.7 ± 10.7. Sisty-sdpercent of the patients were female. Severe subsidence was observed in 66 levels (32.0%). After adjusting for age, bone morphogenetic protein (BMP) use, and number of levels fused, the presence of MC type 2 was significantly associated with lower risk of severe subsidence (OR = 0.28 [0.09-0.88], P = 0.029). Whereas, EP-vBMD did not demonstrate a statistical significance (p = 0.600).The presence of a Modic type 2 change was significantly associated with lower odds of severe subsidence after SA-LLIF. Nonetheless, this significant association was independent from regional EP-vBMD values. This finding suggests that microstructural and/or material property changes associated with Modic type 2 changes might have a protective effect in this patient population.4.

STUDY DESIGN Retrospective state database analysis. OBJECTIVE To quantify the 30- and 90-day emergency department (ED) utilization and inpatient readmission rates after primary cervical arthrodesis, to stratify these findings by surgical approach, and to describe risk factors and conditions precipitating these events. SUMMARY OF BACKGROUND DATA Limited data exist on ED utilization and hospital readmission rates after cervical spine arthrodesis. METHODS The New York State all-payer health-care database was queried to identify all 87,045 patients who underwent primary subaxial cervical arthrodesis from 1997 through 2012. Demographic data and clinical information were extracted. Readmission data were available for the entire study period, whereas ED utilization data collection began later and was therefore analyzed starting in 2005. Incidences of these events within 30 and 90 days of discharge as well as trends over time were tabulated. The conditions prompting these encounters were also collected. Data were analyzed with respect to surgical approach. RESULTS The hospital readmission rate was 4.2% at 30 days and 6.2% at 90 days postoperatively. Approximately 6.2% of patients were managed in the ED without inpatient admission within 30 days and 11.3% within 90 days of surgery. The most common conditions prompting such events were dysphagia or dysphonia, respiratory complications, and infection. ED utilization and readmission rates were lowest after anterior surgeries. A preoperative Charlson Comorbidity Index of 1 or greater and traumatic pathologies were associated with increased risk of subsequent ED utilization or hospital readmission. Thirty-day hospital readmission rates declined after 2010, whereas 30-day ED utilization continued to increase. CONCLUSION Patient comorbidities, traumatic pathologies, and surgical approach are associated with increased postoperative complications. Anterior procedures carry the lowest risk, followed by posterior and then circumferential. Awareness of these findings should help to encourage development of strategies to minimize the rate of postoperative ED utilization and hospital readmission. LEVEL OF EVIDENCE 3.