OBJECTIVE Augmented reality (AR) is a novel technology which, when applied to spine surgery, offers the potential for efficient, safe, and accurate placement of spinal instrumentation. The authors report the accuracy of the first 205 pedicle screws consecutively placed at their institution by using AR assistance with a unique head-mounted display (HMD) navigation system. METHODS A retrospective review was performed of the first 28 consecutive patients who underwent AR-assisted pedicle screw placement in the thoracic, lumbar, and/or sacral spine at the authors' institution. Clinical accuracy for each pedicle screw was graded using the Gertzbein-Robbins scale by an independent neuroradiologist working in a blinded fashion. RESULTS Twenty-eight consecutive patients underwent thoracic, lumbar, or sacral pedicle screw placement with AR assistance. The median age at the time of surgery was 62.5 (IQR 13.8) years and the median body mass index was 31 (IQR 8.6) kg/m(2). Indications for surgery included degenerative disease (n = 12, 43%); deformity correction (n = 12, 43%); tumor (n = 3, 11%); and trauma (n = 1, 4%). The majority of patients (n = 26, 93%) presented with low-back pain, 19 (68%) patients presented with radicular leg pain, and 10 (36%) patients had documented lower extremity weakness. A total of 205 screws were consecutively placed, with 112 (55%) placed in the lumbar spine, 67 (33%) in the thoracic spine, and 26 (13%) at S1. Screw placement accuracy was 98.5% for thoracic screws, 97.8% for lumbar/S1 screws, and 98.0% overall. CONCLUSIONS AR depicted through a unique HMD is a novel and clinically accurate technology for the navigated insertion of pedicle screws. The authors describe the first 205 AR-assisted thoracic, lumbar, and sacral pedicle screws consecutively placed at their institution with an accuracy of 98.0% as determined by a Gertzbein-Robbins grade of A or B.

OBJECTIVE:To explore the relationship between spinal cord compression and hypertension through analysis of blood pressure (BP) variations in a cervical spondylotic myelopathy (CSM) cohort after surgical decompression, along with a review of the literature.METHODS:A single-institution retrospective review of patients with CSM who underwent cervical decompression between 2016 and 2017 was conducted. Baseline clinical and imaging characteristics, preoperative and postoperative BP readings, heart rate, functional status, and pain scores were collected. In addition, a PRISMA guidelines-based systematic review was performed.RESULTS:We identified 264 patients with CSM treated surgically; 149 (56.4%) of these had hypertension. The degree of spinal canal compromise and spinal cord compression, preoperative neurologic examination, and the presence of T2-signal hyperintensity on magnetic resonance imaging were associated with hypertension. Overall mean arterial pressure (MAP) decreased significantly at 1 and 12 months after surgery. Patients without T2-signal hyperintensity on imaging showed a MAP reduction at 12 months postoperatively, whereas those with T2-signal hyperintensity showed a transient MAP reduction at 1 month postoperatively before returning to preoperative values. At 12 months after surgery, 24 of 97 patients (24.7%) with initially uncontrolled hypertension had controlled BP values with significant reduction of MAP, systolic BP, and diastolic BP. Including the present study, 5 articles were eligible for systematic review, with all reporting a BP decrease in patients with CSM after decompression.CONCLUSIONS:Analysis of our retrospective cohort and a systematic review suggest that cervical surgical decompression reduces BP in some patients with CSM. However, this improvement is less apparent in patients with preoperative spinal cord T2-signal hyperintensity.

OBJECTIVE:Differences in morbidity and mortality measures between males and females have been demonstrated for a variety of spinal surgeries, however, studies of anterior cervical discectomy and fusion (ACDF) are limited. To investigate the impact ofsexon 30-day perioperative outcomes of ACDF. METHODS:Retrospective 1:1 propensity score-matched cohort study. Patients who underwent ACDF between 2016 and 2018 were reviewed from the ACS-NSQIP database.Propensity score matchingand subgroup analysis were used. RESULTS:21,180 patients met inclusion criteria. 11,194 patients underwent single-level ACDF and 9986 patients underwent multi-level ACDF. In the single-level group, there were 6168 (55.1%) males and 5026 (44.9%) females. In the multi-level group, there were 5033 (50.4%) males and 4953 (49.6%) females. In both single/multi-level groups, females were more likely to be of older age, be functionally dependent, and have higher BMI and lower preoperative hematocrit level. Males were more likely to be Caucasian, smokers, have myelopathy, diabetes mellitus, hypertension and bleeding disorders. In both single/multi-level groups, except for the higher incidence of urinary tract infection (UTI) in females and myocardial infarction (MI) in males, there were no significant differences in morbidity and mortality between males and females. CONCLUSIONS:Several differences in demographics and baseline health status exist between males and females undergoing ACDF. When attempting to control for comorbid conditions, we found that sex by itself is not an independent risk factor for higher perioperative morbidity or mortality in patients undergoing ACDF, except for the higher incidence of UTI in females and MI in males. These results are important findings for clinicians and spine surgeons while counseling patients undergoing this type of procedure.

OBJECTIVE: Existing data have demonstrated significant differences in morbidity and mortality measures between men and women undergoing various spinal surgeries. However, studies of lumbar fusion surgery have been limited. Thus, we investigated the effects of patient sex on 30-day perioperative outcomes after elective lumbar fusion spine surgery. METHODS: Patients who had undergone lumbar fusion from 2015 to 2018 were reviewed from the American College of Surgeons National Surgical Quality Improvement Program database. Propensity score matching was used to determine whether the patient's sex had influenced the 30day perioperative complications. RESULTS: A total of 44,526 cases had met the inclusion criteria and were reviewed. Of the 44,526 patients, 13,715 had undergone posterior lumbar fusion, 21,993 had undergone posterior/transforaminal lumbar interbody fusion, and 8818 had undergone anterior/lateral lumbar interbody fusion. The women were more likely to be older, functionally dependent, and taking steroids for chronic conditions and to have a higher body mass index and lower preoperative hematocrit level. The men were more likely to be white, to smoke, and to have diabetes mellitus, hypertension, and bleeding disorders. In all cohorts, except for a higher incidence of urinary tract infection in the female patients and myocardial infarction in the male patients, no significant differences were found in morbidity and mortality between the sexes. CONCLUSIONS: Several differences in demographics and baseline health status were found between men and women undergoing lumbar fusion. When attempting to control for comorbid conditions using propensity score matching, we found that sex was an independent predictor of urinary tract infection in women and myocardial infarction in men across major morbidity and mortality categories in patients undergoing lumbar fusion surgery.

Spinal cord injury (SCI) affects approximately 2.5 million people worldwide. The primary phase of SCI is initiated by mechanical trauma to the spinal cord, while the secondary phase involves the ensuing tissue swelling and ischemia that worsen tissue damage and functional outcome. Optimizing blood flow to the spinal cord after SCI can mitigate injury progression and improve outcome. Accurate, sensitive, real-time monitoring is critical to assessing the spinal cord perfusion status and optimizing management, particularly in those with injuries severe enough to require surgery. However, the complex anatomy of the spinal cord vasculature and surrounding structures present significant challenges to such a monitoring strategy. In this study, Doppler ultrasound was hypothesized to be a potential solution to detect and monitor spinal cord tissue perfusion in SCI patients who required spinal decompression and/or stabilization surgeries. This approach could provide real-time visual blood flow information and pulsatility of the spinal cord as biomarkers of tissue perfusion. Importantly, Doppler ultrasound could be readily integrated into the surgical workflow, because the spinal cord was exposed during surgery, thereby allowing easy access for Doppler deployment, while keeping the dura intact. Doppler ultrasound successfully measured blood flow in single and bifurcated microfluidic channels at physiologically relevant flow rates and dimensions in both in-vitro and in-vivo porcine SCI models. Furthermore, perfusion was quantified from the obtained images. Our results provide a promising and viable solution to intraoperatively assess and monitor blood flow at the SCI site to optimize tissue perfusion and improve functional recovery in SCI patients.

OBJECTIVE Incidental durotomy is a common complication of elective lumbar spine surgery seen in up to 11% of cases. Prior studies have suggested patient age and body habitus along with a history of prior surgery as being associated with an increased risk of dural tear. To date, no calculator has been developed for quantifying risk. Here, the authors' aim was to identify independent predictors of incidental durotomy, present a novel predictive calculator, and externally validate a novel method to identify incidental durotomies using natural language processing (NLP). METHODS The authors retrospectively reviewed all patients who underwent elective lumbar spine procedures at a tertiary academic hospital for degenerative pathologies between July 2016 and November 2018. Data were collected regarding surgical details, patient demographic information, and patient medical comorbidities. The primary outcome was incidental durotomy, which was identified both through manual extraction and the NLP algorithm. Multivariable logistic regression was used to identify independent predictors of incidental durotomy. Bootstrapping was then employed to estimate optimism in the model, which was corrected for; this model was converted to a calculator and deployed online. RESULTS Of the 1279 elective lumbar surgery patients included in this study, incidental durotomy occurred in 108 (8.4%). Risk factors for incidental durotomy on multivariable logistic regression were increased surgical duration, older age, revision versus index surgery, and case starts after 4 pm. This model had an area under curve (AUC) of 0.73 in predicting incidental durotomies. The previously established NLP method was used to identify cases of incidental durotomy, of which it demonstrated excellent discrimination (AUC 0.97). CONCLUSIONS Using multivariable analysis, the authors found that increased surgical duration, older patient age, cases started after 4 pm, and a history of prior spine surgery are all independent positive predictors of incidental durotomy in patients undergoing elective lumbar surgery. Additionally, the authors put forth the first version of a clinical calculator for durotomy risk that could be used prospectively by spine surgeons when counseling patients about their surgical risk. Lastly, the authors presented an external validation of an NLP algorithm used to identify incidental durotomies through the review of free-text operative notes. The authors believe that these tools can aid clinicians and researchers in their efforts to prevent this costly complication in spine surgery.

OBJECTIVE:Nonunion is a common complication of spinal fusion surgeries. Electrical stimulation technologies (ESTs)-namely, direct current stimulation (DCS), capacitive coupling stimulation (CCS), and inductive coupling stimulation (ICS)-have been suggested to improve fusion rates. However, the evidence to support their use is based solely on small trials. Here, the authors report the results of meta-analyses of the preclinical and clinical data from the literature to provide estimates of the overall effect of these therapies at large and in subgroups. METHODS:A systematic review of the English-language literature was performed using PubMed, Embase, and Web of Science databases. The query of these databases was designed to include all preclinical and clinical studies examining ESTs for spinal fusion. The primary endpoint was the fusion rate at the last follow-up. Meta-analyses were performed using a Freeman-Tukey double arcsine transformation followed by random-effects modeling. RESULTS:A total of 33 articles (17 preclinical, 16 clinical) were identified, of which 11 preclinical studies (257 animals) and 13 clinical studies (2144 patients) were included in the meta-analysis. Among preclinical studies, the mean fusion rates were higher among EST-treated animals (OR 4.79, p < 0.001). Clinical studies similarly showed ESTs to increase fusion rates (OR 2.26, p < 0.001). Of EST modalities, only DCS improved fusion rates in both preclinical (OR 5.64, p < 0.001) and clinical (OR 2.13, p = 0.03) populations; ICS improved fusion in clinical studies only (OR 2.45, p = 0.014). CCS was not effective at increasing fusion, although only one clinical study was identified. A subanalysis of the clinical studies found that ESTs increased fusion rates in the following populations: patients with difficult-to-fuse spines, those who smoke, and those who underwent multilevel fusions. CONCLUSIONS:The authors found that electrical stimulation devices may produce clinically significant increases in arthrodesis rates among patients undergoing spinal fusion. They also found that the pro-arthrodesis effects seen in preclinical studies are also found in clinical populations, suggesting that findings in animal studies are translatable. Additional research is needed to analyze the cost-effectiveness of these devices.

OBJECTIVE:Scheuermann kyphosis (SK) is an idiopathic kyphosis characterized by anterior wedging of ≥ 5° at 3 contiguous vertebrae managed with either nonoperative or operative treatment. Nonoperative treatment typically employs bracing, while operative treatment is performed with either a combined anterior-posterior fusion or posterior-only approach. Current evidence for these approaches has largely been derived from retrospective case series or focused reviews. Consequently, no consensus exists regarding optimal management strategies for patients afflicted with this condition. In this study, the authors systematically review the literature on SK with respect to indications for treatment, complications of treatment, differences in correction and loss of correction, and changes in treatment over time. METHODS:Using PubMed, Embase, CINAHL, Web of Science, and the Cochrane Library, all full-text publications on the operative and nonoperative treatment for SK in the peer-reviewed English-language literature between 1950 and 2017 were screened. Inclusion criteria involved fully published, peer-reviewed, retrospective or prospective studies of the primary medical literature. Studies were excluded if they did not provide clinical outcomes and statistics specific to SK, described fewer than 2 patients, or discussed results in nonhuman models. Variables extracted included treatment indications and methodology, maximum pretreatment kyphosis, immediate posttreatment kyphosis, kyphosis at last follow-up, year of treatment, and complications of treatment. RESULTS:Of 659 unique studies, 45 met our inclusion criteria, covering 1829 unique patients. Indications for intervention were pain, deformity, failure of nonoperative treatment, and neural impairment. Among operatively treated patients, the most common complications were hardware failure and proximal or distal junctional kyphosis. Combined anterior-posterior procedures were additionally associated with neural, pulmonary, and cardiovascular complications. Posterior-only approaches offered superior correction compared to combined anterior-posterior fusion; both groups provided greater correction than bracing. Loss of correction was similar across operative approaches, and all were superior to bracing. Cross-sectional analysis suggested that surgeons have shifted from anterior-posterior to posterior-only approaches over the past two decades. CONCLUSIONS:The data indicate that for patients with SK, surgery affords superior correction and maintenance of correction relative to bracing. Posterior-only fusion may provide greater correction and similar loss of correction compared to anterior-posterior approaches along with a smaller complication profile. This posterior-only approach has concomitantly gained popularity over the combined anterior-posterior approach in recent years.

Blood loss is an inevitable reality of spine surgery. Excessive loss is associated with increased morbidity and mortality and is frequently combated with allogeneic blood transfusions. Transfusions themselves are associated with increased morbidity, including circulatory overload, lung injury, and acute kidney injury. It is therefore incumbent upon the practicing spine surgeon to be aware of evidence-based interventions capable of reducing blood loss and the risk of transfusion. Here we review the available literature and make recommendation based upon the available evidence.

OBJECTIVE: Increasing patient demand for minimally invasive surgery and increased payer emphasis on quality-based payment schema have created a need for technologies that provide consistent, high-quality outcomes for patients undergoing spine surgery. Robotic assistance is one such technology. We report our early experience with a novel real-time, image-guided robot system for use in short-segment lumbar fusion in patients diagnosed with degenerative disease. METHODS: A consecutive series of patients undergoing robot-assisted 1-level or 2-level lumbar fusion procedures were compared with matched controls who underwent freehand surgery. Screw accuracy, intraoperative outcomes, and 30-day outcomes were compared. RESULTS: We identified 56 patients who underwent 1-level or 2-level lumbar fusion during the study period: 28 who underwent robot-assisted procedures and 28 matched controls who underwent freehand instrumentation placement. No significant differences were found between the robot-assisted surgery cohort and the freehand surgery cohort with respect to matched variables. Patients who underwent robot-assisted surgery had less intraoperative blood loss (266.1 +/- 236.8 mL vs. 598.8 +/- 360.2 mL; P < 0.001) and shorter hospitalizations (3.5 +/- 1.8 days vs. 4.5 +/- 2.0 days; P = 0.01). No differences were noted in complication rates, 30-day outcomes, or screw accuracy. Profiling of our initial series showed an average reduction in operation duration of 4.6 minutes with each additional case. CONCLUSIONS: Patients undergoing robot-assisted fusion experienced less intraoperative blood loss and shorter hospitalizations. The results of this initial experience suggest that an image-guided robotic system may provide similar short-term outcomes compared with freehand instrumentation placement.

OBJECTIVE: Tumors of the cervical spine often encase 1 or both vertebral arteries (VA), presenting the treating surgeon with the dilemma of whether to sacrifice or skeletonize the artery. We propose an algorithm for VA management in surgeries for cervical neoplasms METHODS: A retrospective review was carried out of 67 patients undergoing resection of cervical spine tumors with VA involvement. Patients were categorized by tumor origin (primary vs. metastatic) and degree of circumferential VA involvement: 1) abutment only; 2) <180 degrees circumferential involvement; 3) >180 degrees circumferential involvement without complete encasement; or 4) complete encasement. RESULTS: Twelve patients (18%) underwent VA sacrifice, whereas 55 (82%) underwent VA skeletonization. Compared with 11/30 patients with primary tumors (37%), only 1/37 patients (3%) with metastatic disease underwent VA sacrifice (P < 0.01). This patient had invasion of the V2 arterial wall, requiring VA sacrifice. Odds of VA sacrifice also increased with increasing circumferential involvement (P < 0.01). No patients with simple abutment or 0 degrees-180 degrees circumferential involvement underwent sacrifice, whereas 6 of 10 (60%) with 180 degrees-359 degrees involvement and 6 of 29 (21%) with complete encasement underwent VA sacrifice. Of the 27 patients with >= 180 degrees involvement, the reasons for preserving the VA were metastatic disease at the time of treatment (n = 18), a compromised contralateral VA (n = 7), vertebrobasilar junction aplasia (n = 1), and presence of a radiculomedullary artery at the affected level (n = 1). CONCLUSIONS: Primary tumor disease and >180 degrees of circumferential VA involvement should be considered as indications for intraoperative sacrifice of the VA pending preoperative angiographic evaluation contraindications.

OBJECTIVE:Blood transfusions are given to approximately one-fifth of patients undergoing elective lumbar spine surgery, and previous studies have shown that transfusions are accompanied by increased complications and additional costs. One method for decreasing transfusions is administration of tranexamic acid (TXA). The authors sought to evaluate whether the cost of TXA is offset by the decrease in blood utilization in lumbar spine surgery patients. METHODS:The authors retrospectively reviewed patients who underwent elective lumbar or thoracolumbar surgery for degenerative conditions at a tertiary care center between 2016 and 2018. Patients who received intraoperative TXA (TXA patients) were matched with patients who did not receive TXA (non-TXA patients) by age, sex, BMI, ASA (American Society of Anesthesiologists) physical status class, and surgical invasiveness score. Primary endpoints were intraoperative blood loss, number of packed red blood cell (PRBC) units transfused, and total hemostasis costs, defined as the sum of TXA costs and blood transfusion costs throughout the hospital stay. A subanalysis was then performed by substratifying both cohorts into short-length (1-4 levels) and long-length (5-8 levels) spinal constructs. RESULTS:Of the 1353 patients who met inclusion criteria, 68 TXA patients were matched to 68 non-TXA patients. Patients in the TXA group had significantly decreased mean intraoperative blood loss (1039 vs 1437 mL, p = 0.01). There were no differences between the patient groups in the total costs of blood transfusion and TXA (p = 0.5). When the 2 patient groups were substratified by length of construct, the long-length construct group showed a significant net cost savings of $328.69 per patient in the TXA group (p = 0.027). This result was attributable to the finding that patients undergoing long-length construct surgeries who were given TXA received a lower amount of PRBC units throughout their hospital stay (2.4 vs 4.0, p = 0.007). CONCLUSIONS:TXA use was associated with decreased intraoperative blood loss and significant reductions in total hemostasis costs for patients undergoing surgery on more than 4 levels. Furthermore, the use of TXA in patients who received short constructs led to no additional net costs. With the increasing emphasis put on value-based care interventions, use of TXA may represent one mechanism for decreasing total care costs, particularly in the cases of larger spine constructs.

Blood loss is an inevitable reality of spine surgery. Excessive loss is associated with increased morbidity and mortality and is frequently combated with allogeneic blood transfusions. Transfusions themselves are associated with increased morbidity, including circulatory overload, lung injury, and acute kidney injury. It is therefore incumbent upon the practicing spine surgeon to be aware of evidence-based interventions capable of reducing blood loss and the risk of transfusion. Here we review the available literature and make recommendation based upon the available evidence.

OBJECTIVE:Preoperative endovascular embolization of hypervascular spine tumors can reduce intraoperative blood loss. The extent to which subtotal embolization reduces blood loss has not been clearly established. This study aimed to elucidate a relationship between the extent of preoperative embolization and intraoperative blood loss. METHODS:Sixty-six patients undergoing preoperative endovascular embolization and subsequent resection of hypervascular spine tumors were retrospectively reviewed. Patients were divided into 3 groups: complete embolization (n = 22), near-complete embolization (≥ 90% but < 100%; n = 22), and partial embolization (< 90%; n = 22). Intraoperative blood loss was compared between groups using one-way ANOVA with post hoc comparisons between groups. RESULTS:The average blood loss in the complete embolization group was 1625 mL. The near-complete embolization group had an average blood loss of 2021 mL in surgery. Partial embolization was associated with a mean blood loss of 4009 mL. On one-way ANOVA, significant differences were seen across groups (F-ratio = 6.81, p = 0.002). Significant differences in intraoperative blood loss were also seen between patients undergoing complete and partial embolization (p = 0.001) and those undergoing near-complete and partial embolization (p = 0.006). Pairwise testing showed no significant difference between complete and near-complete embolization (p = 0.57). Analysis of a combined group of complete and near-complete embolization also showed a significantly decreased blood loss compared with partial embolization (p < 0.001). Patient age, tumor size, preoperative coagulation parameters, and preoperative platelet count were not significantly associated with blood loss. CONCLUSIONS:Preoperative endovascular embolization is associated with decreased intraoperative blood loss. In this series, blood loss was significantly less in surgeries for tumors in which preoperative complete or near-complete embolization was achieved than in tumors in which preoperative embolization resulted in less than 90% reduction of tumor vascular blush. These findings suggest that there may be a critical threshold of efficacy that should be the goal of preoperative embolization.

Purpose: Measurement of global spinal alignment (GSA) is an important aspect of diagnosis and treatment evaluation for spinal deformity but is subject to a high level of inter-reader variability. Approach: Two methods for automatic GSA measurement are proposed to mitigate such variability and reduce the burden of manual measurements. Both approaches use vertebral labels in spine computed tomography (CT) as input: the first (EndSeg) segments vertebral endplates using input labels as seed points; and the second (SpNorm) computes a two-dimensional curvilinear fit to the input labels. Studies were performed to characterize the performance of EndSeg and SpNorm in comparison to manual GSA measurement by five clinicians, including measurements of proximal thoracic kyphosis, main thoracic kyphosis, and lumbar lordosis. Results: For the automatic methods, 93.8% of endplate angle estimates were within the inter-reader 95% confidence interval (CI95). All GSA measurements for the automatic methods were within the inter-reader CI95, and there was no statistically significant difference between automatic and manual methods. The SpNorm method appears particularly robust as it operates without segmentation. Conclusions: Such methods could improve the reproducibility and reliability of GSA measurements and are potentially suitable to applications in large datasets—e.g., for outcome assessment in surgical data science.

OBJECTIVE:Myelopathy selectively involving the lower extremities can occur secondary to spondylotic changes, tumor, vascular malformations, or thoracolumbar cord ischemia. Vascular causes of myelopathy are rarely described. An uncommon etiology within this category is diaphragmatic crus syndrome, in which compression of an intersegmental artery supplying the cord leads to myelopathy. The authors present the operative technique for treating this syndrome, describing their experience with 3 patients treated for acute-onset lower-extremity myelopathy secondary to hypoperfusion of the anterior spinal artery. METHODS:All patients had compression of a lumbar intersegmental artery supplying the cord; the compression was caused by the diaphragmatic crus. Compression of the intersegmental artery was probably producing the patients' symptoms by decreasing blood flow through the artery of Adamkiewicz, causing lumbosacral ischemia. RESULTS:All patients underwent surgery to transect the offending diaphragmatic crus. Each patient experienced substantial symptom improvement, and 2 patients made a full neurological recovery before discharge. CONCLUSIONS:Diaphragmatic crus syndrome is a rare or under-recognized cause of ischemic myelopathy. Patients present with episodic acute-on-chronic lower-extremity paraparesis, gait instability, and numbness. Angiography confirms compression of an intersegmental artery that gives rise to a dominant radiculomedullary artery. Transecting the offending diaphragmatic crus can produce complete resolution of neurological symptoms.

OBJECTIVE: The Spinal Instability Neoplastic Score (SINS) is widely used to assess mechanical instability in metastatic spine disease. We sought to identify a cutoff within the "potentially unstable" category, above which lesions were more likely than not to be stabilized. METHODS: We retrospectively reviewed all patients consulted for metastatic spine disease over a 1-year period. Patients were included if they were neurologically intact and had complete medical records, including preoperative imaging of every tumor-involved level. Examined variables included epidural spinal cord compression, SINS, revised Tokuhashi grade, age at consultation, and Karnofsky Performance Status. The primary endpoint was whether or not the lesions were stabilized. RESULTS: The study cohort comprised 51 patients (average age, 61 +/- 2 years) with a total of 436 lesions; 50.5% were lytic, and 31.4% were blastic. The most common primaries were lung (n = 12), breast (n = 10) and prostate (n = 8). The median SINS across all lesions was 5. In both lesion- and patient-based analysis, a SINS >= 10 portended a >50% probability of undergoing stabilization; only 11% of all patients with a SINS <= 9 underwent instrumented fusion. Multivariable analysis demonstrated that SINS (odds ratio [OR], 2.44; P < 0.01) and Karnofsky Performance Status (OR, 1.10; P < 0.01) were independent predictors of stabilization. CONCLUSIONS: For vertebrae affected by metastatic disease, the decision to stabilize remains dependent on both the radiographic lesion properties and the patient's clinical picture. However, our results suggest that lesions with a SINS of <= 9 might not require stabilization.

OBJECTIVEProximal junctional kyphosis (PJK) is a structural complication of spinal fusion in 5%–61% of patients treated for adult spinal deformity. In nearly one-third of these cases, PJK is progressive and requires costly surgical revision. Previous studies have suggested that patient body habitus may predict risk for PJK. Here, the authors sought to investigate abdominal girth and paraspinal muscle size as risk factors for PJK.METHODSAll patients undergoing thoracolumbosacral fusion greater than 2 levels at a single institution over a 5-year period with ≥ 6 months of radiographic follow-up were considered for inclusion. PJK was defined as kyphosis ≥ 20° between the upper instrumented vertebra (UIV) and two supra-adjacent vertebrae. Operative and radiographic parameters were recorded, including pre- and postoperative sagittal vertical axis (SVA), sacral slope (SS), lumbar lordosis (LL), pelvic tilt, pelvic incidence (PI), and absolute value of the pelvic incidence–lumbar lordosis mismatch (|PI-LL|), as well as changes in LL, |PI-LL|, and SVA. The authors also considered relative abdominal girth and the size of the paraspinal muscles at the UIV.RESULTSOne hundred sixty-nine patients met inclusion criteria. On univariate analysis, PJK was associated with a larger preoperative SVA (p < 0.001) and |PI-LL| (p = 0.01), and smaller SS (p = 0.004) and LL (p = 0.001). PJK was also associated with more positive postoperative SVA (p = 0.01), ΔSVA (p = 0.01), Δ|PI-LL| (p < 0.001), and ΔLL (p < 0.001); longer construct length (p = 0.005); larger abdominal girth–to-muscle ratio (p = 0.007); and smaller paraspinal muscles at the UIV (p < 0.001). Higher postoperative SVA (OR 1.1 per cm), smaller paraspinal muscles at the UIV (OR 2.11), and more aggressive reduction in |PI-LL| (OR 1.03) were independent predictors of radiographic PJK on multivariate logistic regression.CONCLUSIONSA more positive postoperative global sagittal alignment and smaller paraspinal musculature at the UIV most strongly predicted PJK following thoracolumbosacral fusion.

BACKGROUND:As vascular tumors, intramedullary hemangioblastomas are associated with significant intraoperative blood loss, making them particularly challenging clinical entities. The use of intraoperative indocyanine green or other fluorescent dyes has previously been described to avoid breaching the tumor capsule, but improved surgical outcomes may result from identifying and ligating the feeder arteries and arterialized draining veins. OBJECTIVE:To describe the use of combined preoperative angiography and intraoperative indocyanine green use for the identification of feeder arteries and arterialized draining veins to decrease blood loss in the resection of intramedullary hemangioblastomas. METHODS:A patient with cervical myelopathy secondary to a large C3 hemangioblastoma and cervicothoracic syrinx underwent a C2-3 laminoplasty with resection of the lesion. To reduce intraoperative blood loss and facilitate safe lesion resection, the vascular architecture of the lesion was defined via preoperative digital subtraction angiography and intraoperative use of indocyanine green. The latter permitted ligation of the major and minor feeding arteries and arterialized veins prior to tumor breach, allowing for facile en bloc resection of the lesion. RESULTS:The lesion was resected en bloc with minimal blood loss (approximately 100 mL) and without intraoperative neuromonitoring signal changes. The patient remained at neurological baseline throughout their stay. CONCLUSION:We present a written and media illustration of a technique for intraoperative indocyanine green use in the en bloc resection of intramedullary hemangioblastoma.

OBJECTIVE: Surgical site infections (SSIs) complicate 1% to 9% of elective spine surgeries. Previously identified risk factors include diabetes mellitus type 2, obesity, and chronic kidney disease. We sought to determine whether the use of postoperative surgical site drains is associated with deep SSIs. METHODS: We retrospectively identified patients operated for deep SSIs after surgery for degenerative spine pathologies between July 2016 and December 2018. Patients were excluded if the reason for operation was other than deep SSI or if their primary operation was for infection or tumor. Using their index procedure and the electronic medical record, patients were matched to controls based on age, surgical invasiveness, International Classification of Diseases, Tenth Revision, Clinical Modification code, race, and sex. Our main outcome of interest was whether drain retention time, total output, or daily output differed significantly between cases and controls. RESULTS: We identified 38 patients who met inclusion criteria. Infected patients had a higher body mass index (34.2 vs. 29.9 kg/m(2); P = 0.001), higher odds of having diabetes mellitus type 2 (55.3% vs. 18.4%; P = 0.002), longer drain retention time (5.5 vs. 3.5 days; P = 0.02), and longer inpatient stay (9.5 vs. 4.3 days; P = 0.005). Multivariable logistic regression demonstrated that even after controlling for the other risk factors, drain retention time independently predicted postoperative surgical site infection (odds ratio: 1.36; P = 0.02). CONCLUSIONS: Prolonged surgical drain retention correlates with risk of deep SSI after surgery for degenerative spine disease independent of surgical invasiveness, diabetes mellitus type 2 status, and total drain output. Our data suggest early postoperative drain removal may potentially decrease the risk of SSI and shorten duration of hospital stay.