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Intramedullary spinal cord tumors (IMSCTs) are rare tumors associated with significant morbidity and mortality. Surgical resection is often indicated for symptomatic lesions but may result in new neurological deficits and decrease quality of life. Identifying predictors of these adverse outcomes may help target interventions designed to reduce their occurrence. Nonetheless, most prior studies have employed population-level datasets with limited granularity.To determine independent predictors of nonroutine discharge, prolonged length of stay (LOS), and 30 day readmission and reoperation, and to deploy these results as a web-based calculator.Retrospective cohort study PATIENT SAMPLE: A total of 235 patients who underwent resection of IMSCTs at a single comprehensive cancer center.Nonroutine discharge, prolonged LOS, 30 day readmission, and 30 day reoperation METHODS: Patients who underwent surgery from June 2002 to May 2020 at a single tertiary center were included. Data was collected on patient demographics, clinical presentation, tumor histology, surgical procedures, and 30 day readmission and reoperation. Functional status was assessed using the Modified McCormick Scale (MMS) and queried preoperative neurological symptoms included weakness, urinary and bowel dysfunction, numbness, and back and radicular pain. Variables significant on univariable analysis at the α≤0.15 level were entered into a stepwise multivariable logistic regression model.Of 235 included cases, 131 (56%) experienced a nonhome discharge and 68 (29%) experienced a prolonged LOS. Of 178 patients with ≥ 30 days of follow-up, 17 (9.6%) were readmitted within 30 days and 13 (7.4%) underwent reoperation. Wound dehiscence (29%) was the most common reason for readmission. Nonhome discharge was independently predicted by older age (OR=1.03/year; p.01), thoracic location of the tumor (OR=2.36; p=.01), presenting with bowel dysfunction (OR=4.09; p=.03), and longer incision length (OR=1.44 per level; p=.03). Independent predictors of prolonged LOS included presenting with urinary incontinence (OR=2.65; p=.05) or a higher preoperative white blood cell count (OR=1.08 per 10We found that neurological presentation, patient demographics, and incision length were important predictors of adverse perioperative outcomes in patients with IMSCTs. The calculators can be used by clinicians for risk stratification, preoperative counseling, and targeted interventions.

Study design This was a cross-sectional study. Objective The objective of this study is to report the impact of COVID-19 on spine surgery fellow education and readiness for practice. Summary of background data COVID-19 has emerged as one of the most devastating global health crises of our time. To minimize transmission risk and to ensure availability of health resources, many hospitals have cancelled elective surgeries. There may be unintended consequences of this decision on the education and preparedness of current surgical trainees. Materials and methods A multidimensional survey was created and distributed to all current AO Spine fellows and fellowship directors across the United States and Canada. Results Forty-five spine surgery fellows and 25 fellowship directors completed the survey. 62.2% of fellows reported >50% decrease in overall case volume since cancellation of elective surgeries. Mean hours worked per week decreased by 56.2%. Fellows reported completing a mean of 188.4±64.8 cases before the COVID-19 crisis and 84.1% expect at least an 11%-25% reduction in case volume compared with previous spine fellows. In all, 95.5% of fellows did not expect COVID-19 to impact their ability to complete fellowship. Only 2 directors were concerned about their fellows successfully completing fellowship; however, 32% of directors reported hearing concerns regarding preparedness from their fellows and 25% of fellows were concerned about job opportunities. Conclusions COVID-19 has universally impacted work hours and case volume for spine surgery fellows set to complete fellowship in the middle of 2020. Nevertheless, spine surgery fellows generally feel ready to enter practice and are supported by the confidence of their fellowship directors. The survey highlights a number of opportunities for improvement and innovation in the future training of spine surgeons. Level of evidence Level III.

Surgical resection is considered standard of care for primary intramedullary astrocytomas, but the infiltrative nature of these lesions often precludes complete resection without causing new post-operative neurologic deficits. Radiotherapy and chemotherapy serve as potential adjuvants, but high-quality data evaluating their efficacy are limited. Here we analyze the experience at a single comprehensive cancer center to identify independent predictors of postoperative overall and progression-free survival.Data was collected on patient demographics, tumor characteristics, pre-operative presentation, resection extent, long-term survival, and tumor progression/recurrence. Kaplan-Meier curves modeled overall and progression-free survival. Univariable and multivariable accelerated failure time regressions were used to compute time ratios (TR) to determine predictors of survival.94 patients were included, of which 58 (62%) were alive at last follow-up. On multivariable analysis, older age (TR = 0.98; p = 0.03), higher tumor grade (TR = 0.12; p 0.01), preoperative back pain (TR = 0.45; p 0.01), biopsy [vs GTR] (TR = 0.18; p = 0.02), and chemotherapy (TR = 0.34; p = 0.02) were significantly associated with poorer survival. Higher tumor grade (TR = 0.34; p = 0.02) and preoperative bowel dysfunction (TR = 0.31; p = 0.02) were significant predictors of shorter time to detection of tumor growth.Tumor grade and chemotherapy were associated with poorer survival and progression-free survival. Chemotherapy regimens were highly heterogeneous, and randomized trials are needed to determine if any optimal regimens exist. Additionally, GTR was associated with improved survival, and patients should be counseled about the benefits and risks of resection extent.

Spine surgery has evolved from the advent of imaging and navigation guidance, particularly with the rise of robotic surgical assistance. Navigation guidance has demonstrated potential for increased accuracy of transpedicular screw placement and resecting primary and metastatic spinal tumors. Robotic surgery is widely accepted in other surgical fields because laparoscopic techniques applied to robots can increase operator dexterity and improve visualization. Robotic assistance with spinal tumors has enjoyed rising interest owing to the potential for safe and minimally traumatic resection. We discuss available robots used for navigation-guided transpedicular screw placement and state-of-the-art robotic techniques for spinal or paraspinal tumor resection.

Intramedullary spinal cord tumors (IMSCTs) are rare neoplasms that have limited treatment options and are associated with high rates of morbidity and mortality. To better understand the genetic basis of these tumors we performed whole exome sequencing on 45 tumors and matched germline DNA, including twenty-nine spinal cord ependymomas and sixteen astrocytomas. Though recurrent somatic mutations in IMSCTs were rare, we identified NF2 mutations in 15.7% of tumors (ependymoma, N = 7; astrocytoma, N = 1), RP1 mutations in 5.9% of tumors (ependymoma, N = 3), and ESX1 mutations in 5.9% of tumors (ependymoma, N = 3). We further identified copy number amplifications in CTU1 in 25% of myxopapillary ependymomas. Given the paucity of somatic driver mutations, we further performed whole-genome sequencing of 12 tumors (ependymoma, N = 9; astrocytoma, N = 3). Overall, we observed that IMSCTs with intracranial histologic counterparts (e.g. glioblastoma) did not harbor the canonical mutations associated with their intracranial counterparts. Our findings suggest that the origin of IMSCTs may be distinct from tumors arising within other compartments of the central nervous system and provides the framework to begin more biologically based therapeutic strategies.

Background Spinal chordomas, a subtype of primary spinal column malignancies (PSCM), are rare tumors with poor prognosis, and we have limited understanding of the molecular drivers of neoplasia. Methods Study design was a retrospective review of prospectively collected data with cross-sectional survival. Archived paraffin embedded pathologic specimens were collected for 133 patients from 6 centers within Europe and North America between 1987 and 2012. Tumor DNA was extracted and the human telomerase reverse transcriptase (hTERT) promoter was sequenced. The hTERT mutational status was correlated with overall survival (OS) and time to first local recurrence. Results Ninety-two chordomas, 26 chondrosarcomas, 7 osteosarcomas, 3 Ewing’s sarcomas, and 5 other malignant spinal tumors were analyzed. Median OS following surgery was 5.8 years (95% CI: 4.6 to 6.9) and median time to first local recurrence was 3.9 years (95% CI: 2.5 to 6.7). Eight chordomas, 2 chondrosarcomas, 1 Ewing’s sarcoma, and 1 other malignant spinal tumor harbored either a C228T or C250T mutation in the hTERT promoter. In the overall cohort, all patients with hTERT mutation were alive at 10 years postoperative with a median OS of 5.1 years (95% CI: 4.5 to 6.6) (P = 0.03). hTERT promoter mutation was observed in 8.7% of spinal chordomas, and 100% of chordoma patients harboring the mutation were alive at 10 years postoperative compared with 67% patients without the mutation (P = 0.05). Conclusions We report for the first time that hTERT promoter mutations C228T and C250T are present in approximately 8.7% of spinal chordomas. The presence of hTERT mutations conferred a survival benefit and could potentially be a valuable positive prognostic molecular marker in spinal chordomas.

Metastatic spinal tumors commonly arise from primary breast cancer. We assessed outcomes and identified associated variables for patients who underwent surgical management for spinal metastases of breast cancer.We retrospectively reviewed patients surgically treated for spinal metastases of breast cancer. Neurologic and functional outcomes were analyzed via Frankel scale and Karnofksy Performance Status (KPS) scores, respectively. Variables associated with Frankel and KPS scores after surgery were identified. Multivariable analysis was used to assess predictors for postoperative survival.Forty-nine patients were identified. There was no significant difference in Frankel scores postoperatively and at last follow-up. KPS scores (P = 0.002) significantly improved at last follow-up. Preoperative non-ambulation and postprocedural complications were associated with non-ambulation postoperatively. Postprocedural complications and disease-free interval (DFI)lt; 24 andlt; 60 months were associated with functional impairment at last follow-up. Current smoking status at the time of surgery (P = 0.021) and triple negative (negative immunohistochemistry for estrogen receptor, progesterone receptor, and HER2) breast cancer (P = 0.038) were significantly associated with shortened postoperative survival.When indicated, surgery for spinal metastases of breast cancer leads to preservation of neurologic status and long-term functional improvement. Preoperative ambulatory status and postprocedural complications were associated with ambulatory status after surgery, while postprocedural complications and shortened DFI were associated with functional status after surgery.Current smoking status at the time of surgery and triple negative breast cancer are negative predictors for postoperative survival after metastatic breast cancer to the spine.

OBJECTIVEResection of metastatic spine tumors can improve patients’ quality of life by addressing pain or neurological compromise. However, resections are often complicated by wound dehiscence, infection, instrumentation failures, and the need for reoperation. Moreover, when reoperations are needed, the most common indication is surgical site infection and wound breakdown. In turn, wound reoperations increase morbidity as well as the length and cost of hospitalization. The aim of this study was to examine perioperative risk factors associated with increased rate of wound reoperations after metastatic spine tumor resection.METHODSA retrospective study of patients at a single institution who underwent metastatic spine tumor resection between 2003 and 2013 was conducted. Factors with a p value < 0.200 in a univariate analysis were included in the multivariate model.RESULTSA total of 159 patients were included in this study. Karnofsky Performance Scale score > 70, smoking status, hypertension, thromboembolic events, hyperlipidemia, increasing number of vertebral levels, and posterior approach were included in the multivariate analysis. Thromboembolic events (95% CI 1.19–48.5, p = 0.032) and number of levels involved were independently associated with increased wound reoperation rates in the multivariate model. For each additional spinal level involved, the risk for wound reoperations increased by 21% (95% CI 1.03–1.43, p = 0.018).CONCLUSIONSAlthough wound complications and subsequent reoperations are potential risks for all patients with metastatic spine tumor, due to adjuvant radiotherapy and other medical comorbidities, this study identified patients with thromboembolic events or those requiring a larger incision as being at the highest risk. Measures intended to decrease the occurrence of perioperative venous thromboembolism and to improve wound care, especially for long incisions, may decrease wound-related revision surgeries in this vulnerable group of patients.

Background Robotic-assisted techniques have been implemented in the surgical treatment of tumors in the pelvis, abdomen, and thorax. In pelvic tumors, robotic-assisted techniques evade the need for sizable surgical exposure, but make stimulation of the nerves of the sacral plexus very difficult. Objective To describe how laparoscopic robotic-assisted surgery can couple with tools such as the nerve stimulator to aid in the resection of presacral masses emanating from the neural elements and potentially improve neurological outcome by preventing inadvertent injury to involved nerves. Methods A patient with a large presacral ganglioneuroma underwent resection using the DaVinci system (Intuitive Surgical, Sunnyvale, California) for robotic assistance. A nerve stimulator was coupled to the bipolar cautery instrument of the DaVinci robot to define the presence of functional nerves in the surroundings of the tumor. Results By coupling a nerve stimulator to the bipolar cautery instrument of the DaVinci robot (Intuitive Surgical), it was possible to identify important neural structures in close proximity to the tumor. After identifying functional nerves, the surgeon was able to preserve them and preserve neurological function avoiding motor dysfunction. Conclusion The use of a nerve stimulator coupled to the bipolar cautery instrument of the DaVinci robot (Intuitive Surgical) during laparoscopic, robotic-assisted surgery for resection of presacral masses is safe and feasible. In addition to the preoperative evaluation, intraoperative monitoring and stimulation of nerves in close proximity to the tumor and also exiting through neural foramina involved by the tumor allowed the surgeon to understand the anatomy and preserve neurological function while obtaining optimal surgical resection.

Background Surgical treatment of severe cervicothoracic kyphotic deformity may require the use of 3-column osteotomies such as the pedicle subtraction osteotomy and vertebral column resection (VCR), or VCR with anterior longitudinal ligament resection. Such procedures are extensive and are associated with high intra- and perioperative morbidity, in part, due to the need for risky reduction maneuvers. Objective To describe a novel technique utilizing a laterally placed articulating hinge to facilitate kyphotic deformity correction of the cervicothoracic spine. Methods A patient with severe chin-on-chest deformity of the cervicothoracic spine presented for evaluation and a 2-stage VCR with anterior longitudinal ligament resection was planned. To reduce the risk of intraoperative neurological injury and for increased control during reduction maneuvers, lateral instrumentation was placed through the chest wall resection above and below the level of VCR, which was adjoined with an articulating hinge rod apparatus. Results Satisfactory reduction of the kyphosis was achieved utilizing the hinge rod apparatus for controlled deformity correction. The patient remained neurologically intact following this procedure with improvement in their spinal alignment. Conclusion We present a novel technique utilizing a lateral hinge rod apparatus for efficient, controlled correction of severe kyphotic deformity.

BACKGROUND AND PURPOSE: The early diagnosis of spinal vascular malformations suffers from the nonspecificity of their clinical and radiologic presentations. Spinal angiography requires a methodical approach to offer a high diagnostic yield. The prospect of false-negative studies is particularly distressing when addressing conditions with a narrow therapeutic window. The purpose of this study was to identify factors leading to missed findings or inadequate studies in patients with spinal vascular malformations. MATERIALS AND METHODS: The clinical records, laboratory findings, and imaging features of 18 patients with spinal arteriovenous fistulas and at least 1 prior angiogram read as normal were reviewed. The clinical status was evaluated before and after treatment by using the Aminoff-Logue Disability Scale. RESULTS: Eighteen patients with 19 lesions underwent a total of 30 negative spinal angiograms. The lesions included 9 epidural arteriovenous fistulas, 8 dural arteriovenous fistulas, and 2 perimedullary arteriovenous fistulas. Seventeen patients underwent endovascular (11) or surgical (6) treatment, with a delay ranging between 1 week and 32 months; the Aminoff-Logue score improved in 13 (76.5%). The following factors were identified as the causes of the inadequate results: 1) lesion angiographically documented but not identified (55.6%); 2) region of interest not documented (29.6%); or 3) level investigated but injection technically inadequate (14.8%). CONCLUSIONS: All the angiograms falsely reported as normal were caused by correctible, operator-dependent factors. The nonrecognition of documented lesions was the most common cause of error. The potential for false-negative studies should be reduced by the adoption of rigorous technical and training standards and by second opinion reviews.

Systematic review.We conducted a systematic review of the literature to answer the following questions regarding the use of steroid therapy in metastatic spinal cord compression (MSCC): 1. In cases of MSCC, what is the effect of steroid administration before definitive radiotherapy or surgery on ambulatory status, bowel and bladder function and survival? 2. What steroid dosing regimens are associated with the best outcomes concerning neurological symptoms and complication prevention in cases of MSCC?Currently, there is significant variation in the initial bolus dose, daily maintenance dose and duration of treatment when steroids are used as a bridge to definitive therapy for MSCC.A literature search following PRISMA guidelines was conducted in June 2016, using Medline via Ovid SP, Medline via PubMed, Embase, Biosis Previews and the Cochrane Library. Search terms used in each database varied slightly to optimize results. All generic steroid formulations were included along with spinal cord compression or myelopathy combined with metastatic or malignant tumors. Papers discussing acute traumatic causes of spinal cord compression were excluded, as were papers discussing cord compression from nonmetastatic tumors or epidural lipomatosis. Subjects were limited to adult humans undergoing definitive treatment with radiotherapy or surgery.Of the 309 papers retrieved, 66 full text studies were reviewed and 6 papers were found to address the stated questions.There is a paucity of high quality literature evaluating the use of steroids in MSCC. On the basis of the evidence available an initial 10 mg intravenous bolus of dexamethasone followed by 16 mg PO QD has been associated with fewer complications compared with 100 mg bolus and 96 mg QD. Weaning of steroids should occur rapidly after definitive treatment. Risk of gastric bleeding or perforation can be managed with the routine use of proton-pump inhibitors.Level IIIa.

OBJECTIVE The aim of this study was to investigate the incidence of spinal tuberculosis (TB) in the US between 2002 and 2011. METHODS The Nationwide Inpatient Sample database from 2002 to 2011 was used to identify patients with a discharge diagnosis of TB and spinal TB. Demographic and hospital data were obtained for all admissions, and included age, sex, race, comorbid conditions, insurance status, hospital location, hospital teaching status, and hospital region. The incidence rate of spinal TB adjusted for population growth was calculated after application of discharge weights. RESULTS A total of 75,858 patients with a diagnosis of TB were identified, of whom 2789 had a diagnosis of spinal TB (3.7%); this represents an average of 278.9 cases per year between 2002 and 2011. The incidence of spinal TB decreased significantly—from 0.07 cases per 100,000 persons in 2002 to 0.05 cases per 100,000 in 2011 (p < 0.001), corresponding to 1 case per 2 million persons in the latter year. The median age for patients with spinal TB was 51 years, and 61% were male; 11.6% were patients with diabetes, 11.4% reported recent weight loss, and 8.1% presented with paralysis. There were 619 patients who underwent spinal surgery for TB, with the most common location being the thoracolumbar spine (61.9% of cases); 50% of patients had instrumentation of 3 or more spinal segments. CONCLUSIONS During the examined 10-year period, the incidence of spinal TB was found to significantly decrease over time in the US, reaching a rate of 1 case per 2 million persons in 2011. However, the absolute reduction was relatively small, suggesting that although it is uncommon, spinal TB remains a public health concern and most commonly affects male patients approximately 50 years of age. Approximately 20% of patients with spinal TB underwent surgery, most commonly in the thoracolumbar spine.

Spinal screw placement is a challenging task due to small bone corridors and high risk of neurological or vascular complications, benefiting from precision guidance/navigation and quality assurance (QA). Implicit to both guidance and QA is the definition of a surgical plan-i.e. the desired trajectories and device selection for target vertebrae-conventionally requiring time-consuming manual annotations by a skilled surgeon. We propose automation of such planning by deriving the pedicle trajectory and device selection from a patient's preoperative CT or MRI. An atlas of vertebrae surfaces was created to provide the underlying basis for automatic planning-in this work, comprising 40 exemplary vertebrae at three levels of the spine (T7, T8, and L3). The atlas was enriched with ideal trajectory annotations for 60 pedicles in total. To define trajectories for a given patient, sparse deformation fields from the atlas surfaces to the input (CT or MR image) are applied on the annotated trajectories. Mean value coordinates are used to interpolate dense deformation fields. The pose of a straight trajectory is optimized by image-based registration to an accumulated volume of the deformed annotations. For evaluation, input deformation fields were created using coherent point drift (CPD) to perform a leave-one-out analysis over the atlas surfaces. CPD registration demonstrated surface error of 0.89 ± 0.10 mm (median ± interquartile range) for T7/T8 and 1.29 ± 0.15 mm for L3. At the pedicle center, registered trajectories deviated from the expert reference by 0.56 ± 0.63 mm (T7/T8) and 1.12 ± 0.67 mm (L3). The predicted maximum screw diameter differed by 0.45 ± 0.62 mm (T7/T8), and 1.26 ± 1.19 mm (L3). The automated planning method avoided screw collisions in all cases and demonstrated close agreement overall with expert reference plans, offering a potentially valuable tool in support of surgical guidance and QA.

Retrospective comparative study.To compare clinical and radiographic outcomes between the S2-alar-iliac (S2AI) and the iliac screw (IS) techniques in the adult population and clarify the clinical strength of S2AI screws.S2AI screws have been described as an alternative method for lumbosacropelvic fixation in place of ISs. The S2AI technique has several advantages with lower prominence, increased ability to directly connect to proximal instrumentation, less extensive dissection of tissue, and enhanced biomechanical strength over the IS technique. However, the clinical significance of these advantages remains unclear.A single-center retrospective review of patients who underwent lumbosacropelvic fixation yielded 25 IS group patients and 65 S2AI group patients. Baseline demographic information, postoperative complications, pain and functional outcomes, and screw-related outcomes were collected.The S2AI group had lower rates of reoperation (8.8% vs. 48.0%, P 0.001), surgical site infection (SSI) (1.5% vs. 44.0%, P 0.001), wound dehiscence (1.5% vs. 36.0%, P 0.001), and symptomatic screw prominence (0.0% vs. 12.0%, P = 0.02) than the IS group, whereas rates of L5-S1 pseudarthrosis, proximal junctional failure, and sacroiliac joint pain were similar in both groups. Statistically significant pain relief and functional recovery were achieved in both groups without any significant intergroup differences. On multivariate analyses, age [odds ratio (OR) = 0.91, P = 0.004] and S2AI instrumentation (OR = 0.08, P 0.001) were protective of reoperation, whereas diabetes mellitus (OR = 10.9, P = 0.03) and preoperative diagnosis of tumor (OR = 12.3, P = 0.04) were associated with SSI, and S2AI instrumentation (OR = 0.09, P 0.001) was protective of SSI.The use of the S2AI technique over the IS technique was an independent predictor of preventing reoperation and SSI, while achieving similar clinical and functional outcomes.4.

Study design This is a retrospective study. Objective To report the safety profile of S2-alar-iliac (S2AI) in patients over 60, comparing S2AI screws with iliac screws (ISs). Summary of background data The surgical management involving the lumbosacropelvic spine remains a challenge due to high mechanical demand and risk of pseudarthrosis. Previous articles showed lower rates of complications in patients receiving S2AI screws than ISs; however, none of them have focused on patients aged over 60 who may harbor significant comorbidities and thus require more meticulous perioperative management, given these invasive and lengthy procedures. Materials and methods Retrospective review of clinical records from 2010 to 2015 identified 60 patients undergoing lumbosacropelvic fixation (17 patients with ISs and 43 patients with S2AI screws) who satisfied the following criteria: (1) patients aged over 60 years old and (2) patients with >1-year follow-up periods. Rates of complications such as unplanned reoperation and cardiorespiratory complications were collected and statistically analyzed. Results Baseline characteristics such as age, sex, and comorbidities were similar in both groups. The S2AI group had lower rates of reoperation (18.6% vs. 47.4%; P=0.02), surgical site infection (2.3% vs. 29.4%; P=0.006), wound dehiscence (2.3% vs. 29.4%; P=0.006), and postoperative anemia (7.0% vs. 29.4%; P=0.03) and had lower total volume of estimated blood loss (EBL) (mL) (1846.4 vs. 2721.2; P=0.02) and transfused red blood cell units (7.2 vs. 4.7; P=0.04) than the IS group, while rates of L5-S1 pseudarthrosis and other cardiorespiratory complications were similar in both groups. In multivariate analysis, operative time, body mass index, and use of S2AI screws over ISs were independent predictors of EBL. Conclusions Use of S2AI screws over ISs in patients aged over 60 was associated with lower rates of reoperation, surgical site infection, wound dehiscence, and lower volume of EBL and red blood cell transfusion and is a viable surgical option.

Objective The primary objective of this study is to examine the effects smoking status on rhBMP-2 supplementation in spinal fusion constructs. Methods Patient records were reviewed retrospectively for a consecutive set of patients who underwent first-time posterolateral, instrumented fusion of the lumbar spine for degenerative spinal disease. All operations included arthrodesis supplementation with rhBMP-2. All patients were followed for at least 2 years. The primary endpoint of this study was reoperation for pseudarthrosis, instrumentation failure, or adjacent segment disease. After a rigorous sensitivity analysis, the measure of association was calculated with a multivariable logistic regression controlling for smoking, age, and number of spinal levels fused. Results Of the 110 patients in the study population, 82 (74.6%) were nonsmokers and 28 (25.5%) were smokers. Among perioperative predictors, smokers were younger in age (53.9 ± 9.6 vs. 61.1 ± 13.1 years; P = 0.008) and had shorter length of inpatient hospital stay (4.1 ± 1.8 vs. 5.3 ± 3.0; P = 0.039). After a mean follow-up of 59 months, the 32% incidence of reoperation for pseudarthrosis, instrumentation failure, or adjacent segment among smokers was statistically significantly higher than the 13.4% incidence in nonsmokers ( P = 0.027). Following multivariable logistic regression, the odds of reoperation among smokers was 4.75-fold higher than for nonsmokers ( P = 0.009; 95% confidence interval, 1.48–15.24). Conclusions While rhBMP-2 supplements arthrodesis of instrumented lumbar fusion constructs, smoking status ascertains the strongest predictor of reoperation for pseudarthrosis, instrumentation failure, and adjacent segment.

Accurate intraoperative localization of target anatomy and adjacent nervous and vascular tissue is essential to safe, effective surgery, and multimodality deformable registration can be used to identify such anatomy by fusing preoperative CT or MR images with intraoperative images. A deformable image registration method has been developed to estimate viscoelastic diffeomorphisms between preoperative MR and intraoperative CT using modality-independent neighborhood descriptors (MIND) and a Huber metric for robust registration. The method, called MIND Demons, optimizes a constrained symmetric energy functional incorporating priors on smoothness, geodesics, and invertibility by alternating between Gauss-Newton optimization and Tikhonov regularization in a multiresolution scheme. Registration performance was evaluated for the MIND Demons method with a symmetric energy formulation in comparison to an asymmetric form, and sensitivity to anisotropic MR voxel-size was analyzed in phantom experiments emulating image-guided spine-surgery in comparison to a free-form deformation (FFD) method using local mutual information (LMI). Performance was validated in a clinical study involving 15 patients undergoing intervention of the cervical, thoracic, and lumbar spine. The target registration error (TRE) for the symmetric MIND Demons formulation (1.3 ± 0.8 mm (median ± interquartile)) outperformed the asymmetric form (3.6 ± 4.4 mm). The method demonstrated fairly minor sensitivity to anisotropic MR voxel size, with median TRE ranging 1.3-2.9 mm for MR slice thickness ranging 0.9-9.9 mm, compared to TRE = 3.2-4.1 mm for LMI FFD over the same range. Evaluation in clinical data demonstrated sub-voxel TRE (

Study design Systematic review and expert consensus. Objective To address the following two questions: (A) Is there a difference in outcomes after spino-pelvic reconstruction of total sacrectomy defects compared with no reconstruction? (B) What constitutes best surgical technique for soft tissue and bony reconstruction after total sacrectomy? Summary of background data The management of the soft tissue and bony defect after total sacrectomy for primary sacral tumors remains a challenge due to the complex anatomical relationships and biomechanical requirements. The scarcity of evidence-based literature in this specialized field makes it difficult for the treating surgeon to make an informed choice. Methods A systematic literature review was performed (1950-2015), followed by a meeting of an international expert panel. Medline, Embase, and CINAHL databases and Cochrane Libraries were searched. Using the GRADE guidelines, the panel of experts formulated recommendations based on the available evidence. Results Three hundred fifty-three studies were identified. Of these, 17 studies were included and were case series. Seven were evaluated as high quality of evidence and nine were of low quality. There were a total of 116 participants. Three studies included patients (n = 24) with no spino-pelvic reconstruction. One study included patients (n = 3) with vascularized bone reconstruction. Twelve studies included patients (n = 80) with no soft tissue reconstruction, three studies described patients with a local flap (n = 20), and four studies with patients having regional flap reconstruction (n = 16). Patients with or without spino-pelvic reconstruction had similar outcomes with regards to walking; however, most patients in the nonreconstructed group had some ilio-lumbar ligamentous stability preserved. The wound dehiscence and return to theater rates were higher in patients with no soft tissue reconstruction. Conclusion We recommend spino-pelvic reconstruction be undertaken with soft tissue reconstruction after total sacrectomy. Level of evidence N/A.

Background In sacropelvic fixation, the iliac screw technique offers biomechanically strong constructs, but its disadvantages include screw prominence, wound dehiscence, and postoperative pain secondary to the high profile nature. To overcome this drawback, S2-alar-iliac (S2AI) screws were developed as an alternative technique for sacropelvic fixation. This study aimed to compare the S2AI screw technique with the iliac screw technique in terms of postoperative symptomatic screw prominence. Methods A retrospective review of the records of sacropelvic fusion procedures performed at a single institution between October 2010 and January 2015 identified 32 patients with 72 iliac screws and 68 patients with 148 S2AI screws, and clinical and radiographic data were collected. If a patient had wound dehiscence and/or tenderness in the buttock immediately overlying a pelvic screw head postoperatively, it was defined as symptomatic screw prominence. The minimal distance from screw head to skin (MDSS) on postoperative computed tomography scans was measured for each patient to clarify the relationship between symptomatic screw prominence and MDSS. Results Mean follow-up period was 22.0 months. There was significantly more symptomatic pelvic screw prominence in the iliac screw group (11.1% vs. 1.4%, P = 0.002). MDSS ≤23 mm was the strongest predictor of symptomatic pelvic screw prominence, which yielded sensitivity of 100%, specificity of 94.1%, positive predictive value of 47.6%, and negative predictive value of 100%. Conclusions The use of the S2AI screw technique resulted in a reduced rate of symptomatic screw prominence. MDSS ≤23 mm was the strongest predictor of symptomatic screw prominence.

To report outcomes after total en bloc spondylectomy (TES) for primary aggressive/malignant tumors of the lumbar spine. We performed a retrospective review of 23 neurosurgical patients operated between 2004 and 2014. Outcomes included perioperative complication rates and reoperation rates for instrumentation failure. The relationship between patient/operative parameters and complication development/instrumentation failure was investigated. There were 15 men (65.2 %) and eight women (24.8 %), with a median of 47 years. The most common tumor was chordoma in 11 patients (47.8 %), followed by sarcoma in four (17.4 %), and giant cell tumor in three (13.0 %). All patients but one underwent a two-staged operation; median total estimated blood loss was 3200 mL and median total operative time was 18.5 h. Fifteen patients developed at least one perioperative complication (65.2 %), with the most common being wound infection and ileus (26.1 % each). There was one case of intraoperative iliac vein injury (4.4 %). Instrumentation failure occurred in 9 patients (39.1 %) at a median time of 23 months after index spondylectomy. Following logistic regression, there were no factors associated with complication development. On the other hand, postoperative radiation was significantly associated with instrumentation failure (OR 7.49; 95 % CI, 1.02–54.9). Local recurrence and 5-year survival was 8.7 and 84.4 %, respectively. Median follow-up time was 50 months. Although favorable oncological outcomes after en bloc resection of spinal tumors may be achieved in terms of recurrence and survival, TES in the lumbar spine remains a challenging procedure. Future investigation into complication avoidance and reconstruction techniques is encouraged.

Background Anterior cervical discectomy and fusion (ACDF) is a commonly performed procedure. Cerebrospinal fluid (CSF) leaks, although uncommon, may occur and can be a potentially serious complication. Little is known regarding the fusion rate after durotomy in ACDF. This study sought to investigate the clinical outcomes and fusion rates of patients with CSF leak after ACDF. Methods In this single-institution retrospective review, 14 patients who experienced CSF leak after ACDF between 1995 and September 2014 were identified. Results The median follow-up was 13.1 months. The diagnoses included spondylosis/degenerative disc disease ( n = 10), disc herniation with radiculopathy ( n = 3), and kyphotic deformity ( n = 1). Of ACDFs, 7 were 1-level, 5 were 2-level, and 2 were 3-level procedures. The posterior longitudinal ligament was intentionally opened in all cases, and the microscope was used in 9 cases. Durotomy was discovered intraoperatively in all cases and was generally repaired with a combination of fibrin glue and synthetic dural replacement. Lumbar drainage was used in 5 patients, and 3 patients reported orthostatic headaches, which resolved within 1 month. Two patients reported hoarseness, and 8 patients reported dysphagia; all cases were transient. Follow-up imaging for fusion assessment was available for 12 patients, and a 100% fusion rate was achieved with no postoperative infections. Conclusions ACDFs with CSF leak had a 100% fusion rate in this series, with generally excellent clinical outcomes, although it is difficult to conclude definitively that there is no effect on fusion rates because of the small sample size. However, given the relative rarity of this complication, this study provides important data in the clinical literature regarding outcomes after CSF leak in ACDFs.

In image-guided spine surgery, robust three-dimensional to two-dimensional (3D-2D) registration of preoperative computed tomography (CT) and intraoperative radiographs can be challenged by the image content mismatch associated with the presence of surgical instrumentation and implants as well as soft-tissue resection or deformation. This work investigates image similarity metrics in 3D-2D registration offering improved robustness against mismatch, thereby improving performance and reducing or eliminating the need for manual masking. The performance of four gradient-based image similarity metrics (gradient information (GI), gradient correlation (GC), gradient information with linear scaling (GS), and gradient orientation (GO)) with a multi-start optimization strategy was evaluated in an institutional review board-approved retrospective clinical study using 51 preoperative CT images and 115 intraoperative mobile radiographs. Registrations were tested with and without polygonal masks as a function of the number of multistarts employed during optimization. Registration accuracy was evaluated in terms of the projection distance error (PDE) and assessment of failure modes (PDE 30 mm) that could impede reliable vertebral level localization. With manual polygonal masking and 200 multistarts, the GC and GO metrics exhibited robust performance with 0% gross failures and median PDE6.4 mm (±4.4 mm interquartile range (IQR)) and a median runtime of 84 s (plus upwards of 1-2 min for manual masking). Excluding manual polygonal masks and decreasing the number of multistarts to 50 caused the GC-based registration to fail at a rate of14%; however, GO maintained robustness with a 0% gross failure rate. Overall, the GI, GC, and GS metrics were susceptible to registration errors associated with content mismatch, but GO provided robust registration (median PDE = 5.5 mm, 2.6 mm IQR) without manual masking and with an improved runtime (29.3 s). The GO metric improved the registration accuracy and robustness in the presence of strong image content mismatch. This capability could offer valuable assistance and decision support in spine level localization in a manner consistent with clinical workflow.

Objective The objective of this study is to analyze time to surgery as both a continuous and discrete variable to determine its association with outcomes in cauda equina syndrome (CES). Methods Patients at a single center whose medical record allowed precise calculation of time to surgery were included. CES was defined as at least four of the following: bladder dysfunction, saddle anesthesia, lower extremity weakness, lower extremity sensory disturbance, bowel dysfunction, or acute lower back or leg pain. Time to surgery was analyzed as a continuous variable using logistic and ordered logistic regression, and as a discrete variable by comparing patients treated before and after set thresholds. Results Forty-five patients were identified. Analysis of time as a continuous variable did not reveal any significant association with outcomes. A parsimonious model with adjustment for age, sex, race, acute onset of CES, saddle anesthesia, motor deficit, and bowel dysfunction at presentation was used to analyze the continuous influence of time to surgery on bladder dysfunction and an aggregate outcome of symptoms. Neither time to surgery nor any of the covariates were significantly associated with either outcome. Discrete analysis of outcomes across thresholds of 12, 24, 36, 48, 60, and 72 hours did not reveal prognostic time points. Conclusion In this single-center CES series, time to surgery did not have a convincing continuous or discrete relationship with outcome. Future prospective studies are needed to determine the best timing for surgery in patients with CES.

Pseudarthrosis occurs after approximately 2-20% of anterior cervical discectomy and fusion (ACDF) procedures; it is unclear if posterior or anterior revision should be pursued. In this study, we retrospectively evaluate the outcomes in 22 patients with pseudarthrosis following ACDF and revision via posterior cervical fusion (PCF). Baseline demographics, preoperative symptoms, operative data, time to fusion failure, symptoms of pseudarthrosis, and revision method were assessed. Fusion outcome and clinical outcome were determined at last follow-up (LFU). Thirteen females (59%) and 9 (41%) males experienced pseudarthrosis at a median of 11 (range: 3-151)months after ACDF. Median age at index surgery was 51 (range: 33-67)years. All patients with pseudarthrosis presented with progressive neck pain, with median visual analog scale (VAS) score of 8 (range: 0-10), and/or myeloradiculopathy. Patients with pseudarthrosis12 months compared to12 months after index surgery were older (p=0.013), had more frequent preoperative neurological deficits (p=0.064), and lower baseline VAS scores (p=0.006). Fusion was successful after PCF in all patients, with median time to fusion of 10 (range: 2-14)months. Eighteen patients fused both anteriorly and posteriorly, two patients fused anteriorly only, and two patients fused posteriorly only. Median VAS neck score at LFU significantly improved from the time of pseudarthrosis (p=0.012). While uncommon, pseudarthrosis may occur after ACDF. All patients achieved successful fusion after subsequent posterior cervical fusion, with 91% fusing a previous anterior pseudarthrosis after posterior stabilization. Neck pain significantly improved by LFU in the majority of patients in this study.

BACKGROUND Adjacent segment disease (ASD) has not been described after laminectomy without fusion. OBJECTIVE To determine the incidence of ASD after a 1- or 2-level lumbar laminectomy. METHODS We retrospectively reviewed medical records of all patients who underwent 1- or 2-level, bilateral lumbar laminectomy without fusion for degenerative spinal disease (all follow-up ≥1 year). ASD was defined as clinical and/or radiographic evidence of degenerative spinal disease that required reoperation at the level above or below the index laminectomy. RESULTS Of the 398 patients, the incidence of ASD requiring reoperation was 10%. The 39 ASD cases were almost equally distributed at L2-L3 (31%), L3-L4 (26%), and L5-S1 (31%), and to a lesser extent at L4-L5 (15%) (P = .51). The ASD incidences of 10% and 9% were equivalent after a 1- and 2-level laminectomy, respectively (P = .76). Rostral ASD was statistically more common than caudal ASD after both the 1- (P < .001) and 2- (P < .001) level laminectomy. Of the 39 ASD cases, 95% required laminectomy, 26% discectomy, and 49% fusion. Average time to ASD was 4 years. After a Kaplan-Meier analysis, time to reoperation for ASD was equivalent among the 1- and 2-level laminectomy cohorts (log-rank test, P = .13). CONCLUSION The cumulative incidence of ASD requiring reoperation was 10% over a mean of 4 years. Both the 1- and 2-level laminectomy cohorts experienced equivalent incidences and rates of ASD. Of the 39 operations for ASD, about half required a fusion.

Background Posterior atlantoaxial fusion is an important armamentarium for neurosurgeons to treat several pathologies involving the craniovertebral junction. Although the potential advantages of recombinant human bone morphogenetic protein-2 (rhBMP-2) are well documented in the lumbar spine, its indication for C1-C2 fusion has not been well characterized. In our institution, we apply rhBMP-2 to the C1-C2 joint either alone or with hydroxyapatite, locally harvested autograft chips, and/or morselized allogenic bone graft for selected cases—without conventional posterior structural bone graft. We report the clinical outcomes of the surgical technique to elucidate its feasibility. Methods We performed a single-center, retrospective review of data from 2008 to 2016 and identified 69 patients who had undergone posterior atlantoaxial fusion with rhBMP-2. The clinical records of these patients were reviewed, and the baseline characteristics, operative data, and postoperative complications were collected and statistically analyzed. Results The average age of the 69 patients was 60.8 ± 4.5 years, and 55.1% were women. With an average follow-up period of 21.1 ± 4.2 months, the C1-C2 fusion rate was 94.3% (65 of 69), and the average time to fusion was 11.4 ± 2.6 months (range, 5–23). The overall reoperation rate was 10.1% (7 of 69), with instrumentation failure in 7 patients (10.1%), adjacent segment disease in 2 (2.9%), and postoperative dysphagia and dyspnea in 2 patients (2.9%). No ectopic bone formation or soft tissue edema developed. Conclusions Although retrospective and from a single center, our study has shown that rhBMP-2 usage at the C1-C2 joint without posterior structural bone grafting is a safe and reasonable surgical option.

Recent work has yielded a method for automatic labeling of vertebrae in intraoperative radiographs as an assistant to manual level counting. The method, called LevelCheck, previously demonstrated promise in phantom studies and retrospective studies. This study aims to: (#1) Analyze the effect of LevelCheck on accuracy and confidence of localization in two modes: (a) Independent Check (labels displayed after the surgeon’s decision) and (b) Active Assistant (labels presented before the surgeon’s decision). (#2) Assess the feasibility and utility of LevelCheck in the operating room. Two studies were conducted: a laboratory study investigating these two workflow implementations in a simulated operating environment with 5 surgeons, reviewing 62 cases selected from a dataset of radiographs exhibiting a challenge to vertebral localization; and a clinical study involving 20 patients undergoing spine surgery. In Study #1, the median localization error without assistance was 30.4% (IQR = 5.2%) due to the challenging nature of the cases. LevelCheck reduced the median error to 2.4% for both the Independent Check and Active Assistant modes (p

OBJECT Spinal metastases from gynecological cancers are rare, with few cases reported in the literature. In this study, the authors examine a series of patients with spinal metastases from gynecological cancer and review the literature. METHODS The cases of 6 consecutive patients who underwent spine surgery for metastatic gynecological cancer between 2007 and 2012 at a single institution were retrospectively reviewed. The recorded demographic, operative, and postoperative factors were reviewed, and the functional outcomes were determined by change in Karnofsky Performance Scale and the American Spine Injury Association (ASIA) score during follow-up. A systematic review of the literature was also performed to evaluate outcomes for patients with similar gynecological metastases to the spine. RESULTS In this series, details regarding metastatic gynecological cancers to the spine are as follows: 2 patients with cervical cancer (both presented at age 46 years, mean postoperative survival of 32 months), 2 patients with endometrial cancer (mean age of 40 years, mean postoperative survival of 26 months), and 2 patients with leiomyosarcoma (mean age of 44 years, mean postoperative survival of 20 months). All patients presented with pain, and no complications were noted following surgery. All patients with known follow-up had stable or improved neurological outcomes, performance status, and improved pain, without local recurrence of tumor. Overall median survival after diagnosis of metastatic spine lesions for all cases in the literature as well as those treated by the authors was 15 months. When categorized by type, median survival of patients with cervical cancer (n = 2), endometrial cancer (n = 26), and leiomyosarcoma (n = 16) was 32, 10, and 22.5 months, respectively. CONCLUSIONS Gynecological cancers metastasizing to the spine are rare. In this series, overall survival following diagnosis of spinal metastasis and surgery was 27 months, with cervical cancer, endometrial cancer, and leiomyosarcoma survival being 32, 26, and 20 months, respectively. Combined with literature cases, survival differs depending on primary histology, with decreasing survival from cervical cancer (32 months) to leiomyosarcoma (22.5 months) to endometrial cancer (10 months). Integrating such information with other patient factors may more accurately guide decision making regarding management of such spinal lesions.

We present a 25-year-old woman with Erdheim-Chester disease (ECD) presenting with progressive myelopathy from multiple compressive spinal epidural lesions who required cervicothoracic decompression and fusion, and summarize the literature on epidural spinal involvement of ECD. ECD is a rare non-Langerhans histiocytosis affecting multiple organ systems through infiltration and characteristically causing multifocal osteosclerosis. Central nervous system involvement, particularly of the spine, is rare.

Giant cell tumors (GCTs) are rare primary bone neoplasms. The best long-term prognosis is achieved via complete tumor excision, but this feat is challenging in the spine due to proximity of blood vessels and nervous tissue. When occurring in the sacrum, GCTs have been removed in an en bloc fashion via combined anterior/posterior approaches, oftentimes with nerve root sacrifice. The purpose of this article is to present a case of a single-staged, posterior-only approach for en bloc resection of a sacral GCT without nerve root sacrifice.A 45-year-old female presented with intractable lower back and leg pain, saddle anesthesia, and lower extremity weakness. She underwent imaging studies, which revealed a lesion involving the S1 and S2 vertebral bodies. Computed tomography guided biopsy revealed the lesion to be a GCT. The patient underwent a posterior-only approach without nerve root sacrifice to achieve an en bloc resection, followed by lumbopelvic reconstruction.Sacrectomy via a single-staged posterior approach with nerve root preservation is a challenging yet feasible procedure for the treatment of giant cell tumors in carefully selected patients.

Cell-free DNA shed by cancer cells has been shown to be a rich source of putative tumor-specific biomarkers. Because cell-free DNA from brain and spinal cord tumors cannot usually be detected in the blood, we studied whether the cerebrospinal fluid (CSF) that bathes the CNS is enriched for tumor DNA, here termed CSF-tDNA. We analyzed 35 primary CNS malignancies and found at least one mutation in each tumor using targeted or genome-wide sequencing. Using these patient-specific mutations as biomarkers, we identified detectable levels of CSF-tDNA in 74% [95% confidence interval (95% CI) = 57-88%] of cases. All medulloblastomas, ependymomas, and high-grade gliomas that abutted a CSF space were detectable (100% of 21 cases; 95% CI = 88-100%), whereas no CSF-tDNA was detected in patients whose tumors were not directly adjacent to a CSF reservoir (P0.0001, Fisher's exact test). These results suggest that CSF-tDNA could be useful for the management of patients with primary tumors of the brain or spinal cord.

OBJECT Clinical outcomes in patients with primary spinal osteochondromas are limited to small series and sporadic case reports. The authors present data on the first long-term investigation of spinal osteochondroma cases. METHODS An international, multicenter ambispective study on primary spinal osteochondroma was performed. Patients were included if they were diagnosed with an osteochondroma of the spine and received surgical treatment between October 1996 and June 2012 with at least 1 follow-up. Perioperative prognostic variables, including patient age, tumor size, spinal level, and resection, were analyzed in reference to long-term local recurrence and survival. Tumor resections were compared using Enneking appropriate (EA) or Enneking inappropriate surgical margins. RESULTS Osteochondromas were diagnosed in 27 patients at an average age of 37 years. Twenty-two lesions were found in the mobile spine (cervical, thoracic, or lumbar) and 5 in the fixed spine (sacrum). Twenty-three cases (88%) were benign tumors (Enneking tumor Stages 1–3), whereas 3 (12%) exhibited malignant changes (Enneking tumor Stages IA–IIB). Sixteen patients (62%) underwent en bloc treatment—that is, wide or marginal resection—and 10 (38%) underwent intralesional resection. Twenty-four operations (92%) followed EA margins. No one received adjuvant therapy. Two patients (8%) experienced recurrences: one in the fixed spine and one in the mobile spine. Both recurrences occurred in latent Stage 1 tumors following en bloc resection. No osteochondroma-related deaths were observed. CONCLUSIONS In the present study, most patients underwent en bloc resection and were treated as EA cases. Both recurrences occurred in the Stage 1 tumor cohort. Therefore, although benign in character, osteochondromas still require careful management and thorough follow-up.

A 3-dimensional-2-dimensional (3D-2D) image registration algorithm, "LevelCheck," was used to automatically label vertebrae in intraoperative mobile radiographs obtained during spine surgery. Accuracy, computation time, and potential failure modes were evaluated in a retrospective study of 20 patients.To measure the performance of the LevelCheck algorithm using clinical images acquired during spine surgery.In spine surgery, the potential for wrong level surgery is significant due to the difficulty of localizing target vertebrae based solely on visual impression, palpation, and fluoroscopy. To remedy this difficulty and reduce the risk of wrong-level surgery, our team introduced a program (dubbed LevelCheck) to automatically localize target vertebrae in mobile radiographs using robust 3D-2D image registration to preoperative computed tomographic (CT) scan.Twenty consecutive patients undergoing thoracolumbar spine surgery, for whom both a preoperative CT scan and an intraoperative mobile radiograph were available, were retrospectively analyzed. A board-certified neuroradiologist determined the "true" vertebra levels in each radiograph. Registration of the preoperative CT scan to the intraoperative radiograph was calculated via LevelCheck, and projection distance errors were analyzed. Five hundred random initializations were performed for each patient, and algorithm settings (viz, the number of robust multistarts, ranging 50-200) were varied to evaluate the trade-off between registration error and computation time. Failure mode analysis was performed by individually analyzing unsuccessful registrations (5 mm distance error) observed with 50 multistarts.At 200 robust multistarts (computation time of ∼26 s), the registration accuracy was 100% across all 10,000 trials. As the number of multistarts (and computation time) decreased, the registration remained fairly robust, down to 99.3% registration accuracy at 50 multistarts (computation time ∼7 s).The LevelCheck algorithm correctly identified target vertebrae in intraoperative mobile radiographs of the thoracolumbar spine, demonstrating acceptable computation time, compatibility with routinely obtained preoperative CT scans, and warranting investigation in prospective studies.N/A.

Renal cell carcinoma (RCC) is an aggressive disease that metastasizes to the spine often requiring surgery. However, selecting the appropriate surgical intervention can be challenging. The Tokuhashi scoring system can be used to predict survival and inform the surgical strategy. We set out to determine the Tokuhashi score for patients with RCC spine metastases and compare expected and observed survival. Records were reviewed for all patients who underwent surgery for spinal metastases at a single institution from January 2000 to December 2011 to determine the Tokuhashi score and survival. Kaplan–Meier estimates and log-rank test for univariate analysis were performed with R version 2.15.12 (R Foundation, 2012). Thirty patients underwent 40 spinal operations for metastatic RCC. Median survival was 11.4 months. Preoperative Tokuhashi scores were: 12–15, 15 patients; 9–11, seven patients; 0–8, eight patients. Median survival was 32.9, 11.7, and 5.4 months, respectively. Bone (p = 0.01) and visceral metastases (p = 0.005), and KPS (p = 0.002) significantly affected survival. Tokuhashi score predicted survival (p = 0.016); survival differed between the high and low score groups (p = 0.006). RCC is an aggressive disease with short life expectancy when metastatic to the spine. However, patients with low systemic disease burden and solitary spinal metastases can have long survival and benefit from excisional surgery. Tokuhashi score can be useful in selecting surgical intervention in patients with RCC spinal metastases, and may be more relevant than in other cancers with spinal metastases.

Pseudoarthrosis is a known complication following lumbar fusion, and although several risk factors have been established, the association of durotomy and pseudoarthrosis has not been studied to our knowl- edge. A retrospective review was performed to identify all adult patients who underwent lumbar pos- terolateral fusion (without interbody fusion) for degenerative spine disease over a 20 year period at a single institution. Patients were divided into durotomy and no durotomy cohorts. Patients were included if they had at least 1 year of follow-up. The main outcome variable was development of pseudoarthrosis. A total of 327 patients were identified, of whom 17 (5.19%) had a durotomy. Pseudoarthrosis rates were significantly higher in the durotomy group (35.29%) when compared to the no durotomy group (13.87%), with the difference being statistically significant (p = 0.016). Univariate analysis revealed that durotomy (p = 0.003) and the number of levels fused (p = 0.015) were the only two significant risk factors for pseu- doarthrosis. After controlling for the number of levels fused, the adjusted relative risk (RR) revealed that patients with a durotomy were 2.23 times more likely to develop pseudoarthrosis (RR 2.23; 95% confi- dence interval 1.05-4.75) when compared to patients without durotomy. The findings in the present study suggest an association between durotomy and pseudoarthrosis development. Patients with a dur- otomy were 2.2 times more likely to develop pseudoarthrosis compared to patients without a durotomy. Future and larger studies are required to corroborate our findings.

OBJECT Multiple myeloma is the most common primary tumor of the spine and is the most common primary malignant tumor of bone. Although spinal myeloma is classically a radiosensitive lesion, clinical or radiographic signs of instability merit surgical intervention. The authors present the epidemiology, surgical indications, and outcome data of a series of consecutive cases involving 31 surgically treated patients with diagnoses of multiple myeloma and plasmacytoma of the spine (the largest such series reported to date). METHODS Surgical instability was the criterion for operative intervention in this patient cohort. The Spinal Instability Neoplastic Score (SINS) was used to make this assessment of instability. The cases were analyzed using location of the lesion, spinal levels involved, Frankel score, adjuvant therapy, functional outcome, and patient survival. RESULTS All patients undergoing surgical intervention were determined to have indeterminate or gross spinal column instability according to SINS criteria. The median survival was 78.9 months. No significant difference in survival was seen for patients with higher SINS scores or for older patients (> 55 years). There was a statistically significant difference in survival benefit observed for patients receiving chemotherapy and radiation versus radiation alone as an adjuvant to surgery (p = 0.02). CONCLUSIONS In this 10-year analysis, the authors report outcomes of surgical intervention for patients with indeterminate or gross spinal instability due to multiple myeloma and plasmacytoma of the spine with improved neurological function following surgery and low rates of instrumentation failure.

Repeated cohort studies have consistently demonstrated a survival advantage after en bloc resection for locally aggressive primary tumors in the sacrum. A sacrectomy is often required to remove the tumor en bloc, which may necessitate the sacrifice of sacral nerves. This can potentially result in functional complications, including the impairment of gait, bowel function, or bladder function.To assess the bladder, bowel, and motor functions of patients after resection of a primary sacral tumor.This was a retrospective cohort study at a single academic institution.Consecutive patients who underwent an en bloc sacral tumor resection at a single institution between December 2002 and June 2012 were included. The study population comprised 73 patients.Patients were classified as having had a low, middle, high, or total sacrectomy based on the level of sacral nerves sacrificed, if applicable.Patient data were collected from clinic notes and hospital records that included operative notes, lab studies, and rehabilitation notes.Across all patients, there was no change in bowel function after sacrectomy, whereas bladder and motor functions returned to preoperative (pre-op) levels at 3 and 6 months, respectively. Higher level sacrectomies were associated with worse bowel (p.001), bladder (p.001), and motor (p=.027) functions 12 months postoperatively (post-op). At 1 year, none of the six patients with a high or total sacrectomy had intact bladder function and 14.3% (N=7) had intact bowel function. Of patients with a middle sacrectomy, 62.5% (N=8) had intact bladder function and 71.4% (N=7) had intact bowel function at 1 year. Of patients with a low sacrectomy, 91.7% (N=12) had intact bladder function and 91.7% (N=12) had intact bowel function.Preoperative bladder, bowel, and motor functions, level of sacral tumor involvement, and corresponding level of sacrectomy were the greatest predictors of long-term bladder, bowel, and motor functions. There were no statistically significant changes in bladder, bowel, or motor functions from pre-op to 6 months post-op, and therefore, pre-op functional status was predictive of long-term function.

Patients with end stage renal disease on hemodialysis may present with destructive spondyloarthropathy of the spine, most commonly in the subaxial cervical and lumbar spine, often with severe stenosis and instability. However, surgical management of these patients is challenging due to a high pseudarthrosis rate, poor bone quality, and medical frailty. We present a 49-year-old man on hemodialysis who presented with C4–C5 vertebral body destruction and a focal kyphotic deformity with myelopathy. The patient underwent a 360 degree decompression and reconstructive procedure that resulted in posterior instrumentation failure. Several salvage techniques were used in order to adequately stabilize the spine while preserving the patient’s remaining cervical motion.

Background context Spinal sarcomas are aggressive tumors that originate from the cells of mesechymal origin, specifically fat, cartilage, bone, and muscle. They are high-grade lesions, and treatment of spinal sarcomas can involve chemotherapy, radiation therapy, and surgery. In the appendicular skeleton, sarcomas are often treated with amputation, however, in the spinal column, surgical resection poses a unique set of challenges. Purpose To better understand the optimal treatment regimens and the impact of en bloc or intralesional resection on patient outcome. Study design A cohort of 25 sarcoma patients treated at a single medical institution between 2002 and 2012 was reviewed. Patient sample and outcome measures Patients were classified by tumor type for subgroup analysis, including chondrosarcoma, osteosarcoma, and other malignant spinal sarcomas. Demographic data for review included patient age, tumor type, tumor location, surgery type, exposure to chemotherapy, and radiation therapy. Methods Survival statistics and Kaplan-Meier curves were calculated using GraphPad Prism 5.0. The threshold for statistical significance was set at p t tests were performed for statistical analyses in Microsoft Excel 2010. Results Twenty-five patients with spinal sarcomas were treated over the 10-year period. Diagnosis included chondrosarcoma (n=9), osteosarcoma (n=4), and other sarcomas (n=12). Mean age at the time of diagnosis was 42 years. Pain was present at the time of diagnosis in 92% patients. Median survival after surgery was 59.5 months for chondrosarcoma, undefined for other sarcomas, and 16.8 months for osteosarcoma. Median survival after en bloc resection was undefined. Median survival after intralesional resection was 17.8 months. The difference in median survival between en bloc and intralesional resection was statistically significant (p=.049). Conclusions The authors report the largest cohort of patients with spinal sarcoma. Median survival in this cohort was the longest for patients with sarcomas of varying pathologies. Median survival was longer for chondrosarcoma. En bloc resection demonstrated a survival advantage over intralesional resection. Long-term follow-up is needed for patients with spinal sarcoma to establish definitive survival data.

Percutaneous pelvic screw placement is challenging due to narrow bone corridors surrounded by vulnerable structures and difficult visual interpretation of complex anatomical shapes in 2D x-ray projection images. To address these challenges, a system for planning, guidance, and quality assurance (QA) is presented, providing functionality analogous to surgical navigation, but based on robust 3D-2D image registration techniques using fluoroscopy images already acquired in routine workflow. Two novel aspects of the system are investigated: automatic planning of pelvic screw trajectories and the ability to account for deformation of surgical devices (K-wire deflection). Atlas-based registration is used to calculate a patient-specific plan of screw trajectories in preoperative CT. 3D-2D registration aligns the patient to CT within the projective geometry of intraoperative fluoroscopy. Deformable known-component registration (dKC-Reg) localizes the surgical device, and the combination of plan and device location is used to provide guidance and QA. A leave-one-out analysis evaluated the accuracy of automatic planning, and a cadaver experiment compared the accuracy of dKC-Reg to rigid approaches (e.g., optical tracking). Surgical plans conformed within the bone cortex by 3–4 mm for the narrowest corridor (superior pubic ramus) and >5 mm for the widest corridor (tear drop). The dKC-Reg algorithm localized the K-wire tip within 1.1 mm and 1.4° and was consistently more accurate than rigid-body tracking (errors up to 9 mm). The system was shown to automatically compute reliable screw trajectories and accurately localize deformed surgical devices (K-wires). Such capability could improve guidance and QA in orthopaedic surgery, where workflow is impeded by manual planning, conventional tool trackers add complexity and cost, rigid tool assumptions are often inaccurate, and qualitative interpretation of complex anatomy from 2D projections is prone to trial-and-error with extended fluoroscopy time.

A multi-stage image-based 3D-2D registration method is presented that maps annotations in a 3D image (e.g. point labels annotating individual vertebrae in preoperative CT) to an intraoperative radiograph in which the patient has undergone non-rigid anatomical deformation due to changes in patient positioning or due to the intervention itself. The proposed method (termed msLevelCheck) extends a previous rigid registration solution (LevelCheck) to provide an accurate mapping of vertebral labels in the presence of spinal deformation. The method employs a multi-stage series of rigid 3D-2D registrations performed on sets of automatically determined and increasingly localized sub-images, with the final stage achieving a rigid mapping for each label to yield a locally rigid yet globally deformable solution. The method was evaluated first in a phantom study in which a CT image of the spine was acquired followed by a series of 7 mobile radiographs with increasing degree of deformation applied. Second, the method was validated using a clinical data set of patients exhibiting strong spinal deformation during thoracolumbar spine surgery. Registration accuracy was assessed using projection distance error (PDE) and failure rate (PDE 20 mm-i.e. label registered outside vertebra). The msLevelCheck method was able to register all vertebrae accurately for all cases of deformation in the phantom study, improving the maximum PDE of the rigid method from 22.4 mm to 3.9 mm. The clinical study demonstrated the feasibility of the approach in real patient data by accurately registering all vertebral labels in each case, eliminating all instances of failure encountered in the conventional rigid method. The multi-stage approach demonstrated accurate mapping of vertebral labels in the presence of strong spinal deformation. The msLevelCheck method maintains other advantageous aspects of the original LevelCheck method (e.g. compatibility with standard clinical workflow, large capture range, and robustness against mismatch in image content) and extends capability to cases exhibiting strong changes in spinal curvature.

Study Design. Retrospective study. Objective. To study the impact of smoking status on postoperative complications and pseudarthrosis in adult patients undergoing posterolateral fusion (PLF) of the lumbar spine. Summary of Background Data. Results of studies analyzing the impact of smoking on complication and pseudarthrosis rates after spine surgery are conflicting. Methods. A retrospective medical record review was performed to identify all adult patients who underwent single- and 2-level instrumented PLF without interbody devices for degenerative spine disease in a 21-year period at a single institution. Patients were divided into smokers and nonsmokers. The main outcome variables were development of at least one postoperative complication and development of pseudarthrosis. Results. A total of 281 patients underwent single- or 2-level PLF in the 21-year period. Of these, 231 (82.21%) patients were nonsmokers and 50 (17.9%) were smokers. For patients undergoing single-level PLF, complication rates in nonsmokers (3.57%) versus smokers (7.69%) were not significantly different (P = 0.353); pseudarthrosis in nonsmokers occurred in 9.82% of cases compared with 7.69% in the smokers group (P = 0.738). Nonsmokers undergoing 2-level PLF had complication rates of 6.72%, compared with 4.17% in smokers (P = 0.638), but pseudarthrosis rates were significantly higher in the smokers group than in the nonsmokers group (29.17% vs. 10.92%; P = 0.019). Patients were followed up for an average of 53.5 months. Conclusion. The findings in this study suggest that smoking has a significant impact on pseudarthrosis rates after 2-level PLF of the lumbar spine, but not necessarily on single-level PLF. Conclusion. Level of Evidence: 4

BACKGROUND C5 palsy is a known cause of postoperative deltoid weakness. Prognostic variables affecting the incidence of the palsy have been poorly understood. OBJECTIVE To determine the incidence and perioperative characteristics/predictors of C5 palsy after anterior vs posterior operations. METHODS All patients undergoing C4-5 operations for degenerative conditions were retrospectively reviewed over 21 years. Anterior operations included an anterior cervical discectomy and fusion (ACDF) or a corpectomy, whereas posterior operations included laminectomy and fusion (± foraminotomies). RESULTS Of the total 1001 operations, in 49.0% anterior and 51.0% posterior cases, there was an overall C5 palsy incidence of 5.2% (52 cases): 1.6% and 8.6%, respectively (P < .001). Of the 99 corpectomies, the palsy incidence of 4.0% was not only higher than ACDFs (1.0%), but also followed an upward trend with increasing corpectomy levels (P = .009). Of the 69 posterior and 83 anterior C4-5 foraminotomies, the incidence of C5 palsy was statistically higher in the posterior (14.5%) vs anterior (2.4%) cohort (P = .01). Multiple logistical regression identified older age as the strongest predictor of C5 palsy in the anterior (P = .02) and C4-5 foraminotomy in the posterior (P = .06) cohort. This condition improved within 3 to 6 months in 75% of patients in the anterior and 88.6% in the posterior cohort after a mean follow-up of 14.4 and 27.6 months, respectively. CONCLUSION In one of the largest cohorts on C5 palsy, we found in anterior operations an increasing number of corpectomy levels had a higher incidence of C5 palsy; however, older age was the strongest predictor of C5 palsy. In posterior operations, C4-5 foraminotomy carried the strongest correlation.

Background Adjacent segment disease (ASD) development is known to occur after anterior cervical discectomy and fusion (ACDF). Objective To study the relationship between index ACDF levels and the location of ASD development (above/below), as well as the effect of fusion length on ASD development. Methods We report 888 patients who underwent ACDF for cervical spondylosis over a twenty-year period at a single institution. Of these patients, 108 had re-do surgery due to symptomatic ASD. Patients were followed for an average of 92.4 ± 52.6 months after the index ACDF. Results In agreement with previous ACDF case series, we found the highest rates of cervical spinal degenerative disease requiring surgery at C5/C6, followed by C6/C7. Interestingly, neither the inherent location of index ACDF nor the length of instrumented arthrodesis appeared to correlate with the propensity to develop ASD. However, patients were more likely to develop ASD above the index level of fusion. This was true even for patients undergoing a second revision surgery due to recurrent ASD. Importantly, our data are consistent with existing in vitro biomechanical data in cadaveric spines. Conclusion We describe in detail the location and length of arthrodesis for index ACDFs, as well as first and second revision fusion surgeries in one of the largest Western cohorts in the literature. Our findings support the theory that iatrogenically introduced stress and instability at adjacent spinal segments contribute to the pathogenesis of ASD.

Study design Retrospective clinical study. Objective To study the long-term effects of repeat cervical fusion after development of adjacent segment disease (ASD). Summary of background data ASD is a well-recognized development after anterior cervical discectomy and fusion (ACDF). Although there are data on the development of ASD after ACDF, the incidence of ASD after repeat ACDF has not been well established. Methods We collected 888 consecutive patients who underwent ACDF for cervical degenerative disease during a 20-year period at a single institution. Patients were followed for an average of 94.0 ± 78.1 months after the first ACDF. Results Of the 888 patients who underwent ACDF, 108 patients developed ASD, necessitating a second cervical fusion. Among these 108 patients, 27 patients later developed recurrent ASD, requiring a third cervical fusion. Thus, in this series, the incidence of ASD after ACDF is 12.2%, statistically increasing to 25% after a second cervical fusion (P = 0.0002). Notably, ASD occurred 47.0 ± 44.9 months after the first ACDF and statistically decreased to 30.3 ± 24.9 months after a second cervical fusion (P = 0.01). Of the 77 patients who underwent a second cervical fusion via an anterior approach, 23 developed recurrent ASD requiring a third cervical fusion. In contrast, of the 31 patients who had a posteriorly approached second cervical fusion, only 4 developed recurrent ASD requiring a third cervical fusion. Conclusion We present a cohort of patients undergoing multiple sequential operations due to ASD during a 20-year period. In this series of 888 patients, the incidence of ASD development is lowest after the first ACDF. Patients who undergo a second cervical fusion develop ASD at both higher and faster rates. Moreover, patients who had a second cervical fusion via an anterior approach had a higher chance of developing recurrent ASD versus patients who had a posterior approach. Level of evidence 3.

Background context Cancer is a major global public health problem responsible for one in every four deaths in the United States. Prostate cancer alone accounts for 29% of all cancers in men and is the sixth leading cause of death in men. It is estimated that up to 30% of patients with cancer will develop metastatic disease, the spine being one of the most frequently affected sites in patients with prostate cancer. Purpose To study this condition in a preclinical setting, we have created a novel animal model of human metastatic prostate cancer to the spine and have characterized it histologically, functionally, and via bioluminescence imaging. Study design Translational science investigation of animal model of human prostate cancer in the spine. Methods Luciferase-positive human prostate tumor cells PC3 (PC3-Luc) were injected in the flank of athymic male rats. PC3-Luc tumor samples were then implanted into the L5 vertebral body of male athymic rats (5 weeks old). Thirty-two rats were randomized into three surgical groups: experimental, control, and sham. Tumor growth was assessed qualitatively and noninvasively via bioluminescence emission, upon luciferin injection. To determine the functional impact of tumor growth in the spine, rats were evaluated for gait abnormalities during gait locomotion using video-assisted gait analysis. Rats were euthanized 22 days after tumor implantation, and spines were subjected to histopathological analyses. Results Twenty days after tumor implantation, the tumor-implanted rats showed distinct signs of gait disturbances: dragging tail, right- or left–hind limb uncoordination, and absence of toe clearance during forward limb movement. At 20 days, all rats experienced tumor growth, evidenced by bioluminescent signal. Locomotion parameters negatively affected in tumor-implanted rats included stride length, velocity, and duration. At necropsy, all spines showed evidence of tumor growth, and the histological analysis found spinal cord compression and peritumoral osteoblastic reaction characteristic of bony prostate tumors. None of the rats in the sham or control groups demonstrated any evidence of bioluminescence signal or signs of gait disturbances. Conclusions In this project, we have developed a novel animal model of metastatic spine cancer using human prostate cancer cells. Tumor growth, evaluated via bioluminescence and corroborated by histopathological analyses, affected hind limb locomotion in ways that mimic motor deficits present in humans afflicted with metastatic spine disease. Our model represents a reliable method to evaluate the experimental therapeutic approaches of human tumors of the spine in animals. Gait locomotion and bioluminescence analyses can be used as surrogate noninvasive methods to evaluate tumor growth in this model.

In 2007, members of our group reported a 21 month median survival for patients undergoing surgery for metastatic breast cancer in the spinal column. Cervical spine metastases were associated with decreased survival, Estrogen receptor positivity was associated with improved survival, and age and visceral metastases did not significantly impact survival. In the current study, we reassess these variables in the context of modern adjuvant therapies, and investigate the impact of the Spinal Instability Neoplastic Score (SINS). We report an observational cohort of 43 patients undergoing surgical resection for metastatic breast cancer of the spine treated at a single academic institution from June 2002 to August 2011. Patient medical records were reviewed in accordance with policies outlined by the University Institutional Review Board. Median overall survival following surgery for metastatic breast cancer in the spine was 26.8 months. 1 year overall survival was 66%. 5 year-overall survival was 4%. Age (p=0.12), preoperative functional status (p=0.17), location of metastasis (p=0.34), the presence of visceral metastases (p=0.68), and spinal instability (p=0.81) were not significant variables on survival analysis. Postoperative adjuvant therapy with a single modality (radiation or chemotherapy) was associated with a significantly lower median survival compared to dual therapy with chemotherapy and radiation (p=0.042). Patients that received radiation and chemotherapy after surgery were younger but demonstrated prolonged median survival versus single modality therapy. This data supports the concept that visceral metastases do not impact survival, however cervical spine lesions were not associated with decreased survival.

Resection of metastatic pheochromocytomas may be complicated by transient postoperative neurological deficits due to hypotension. The authors report the first case of en bloc excision of a spinal pheochromocytoma with associated long-term hypertensive management off all medication. Interestingly, this is the first case of transient hypotension following en bloc resection of pheochromocytoma associated with temporary hypotension-associated neurological decline that resolved completely after correction of hypotension postoperatively. A 23-year-old man with a prior adrenalectomy for pheochromocytoma presented with focal thoracic pain. He had a known T-10 vertebral body lesion for which he received chemotherapy and radiation therapy. Imaging demonstrated increased destruction of the T-10 vertebral body, which was concerning for tumor growth. The patient underwent angiographic embolization followed by single-stage posterior en bloc vertebrectomy with placement of a cage and posterior instrumentation and fusion without event. However, approximately 24 hours after surgery, the patient's systolic blood pressure was consistently no higher than 70 mm Hg. During this time, he began suffering from severe bilateral lower-extremity weakness. His systolic blood pressure increased with dopamine, and his strength immediately improved. The patient's oral regimen of adrenergic blockade was stopped, and he recovered without event. Since that time, the patient has been symptom free and requires no antihypertensive medication. The role of en bloc resection for metastatic lesions of the spine is controversial but may be warranted in cases of metastatic pheochromocytoma. En bloc resection avoids intralesional tumor resection and thus may help prevent complications of hypertensive crisis associated with hormonal secretion and extensive blood loss, which are not uncommon with pheochromocytoma resection surgeries. Additionally, the role of en bloc spondylectomy in this setting may allow for metabolic treatment as patients with actively secreting tumors may no longer require antiadrenergic medications.

Background Spinal synovial cysts are a known cause of back pain and radiculopathy. With the advent of high-resolution imaging techniques, synovial cysts are increasingly diagnosed. There are a variety of treatment options for these lesions. Methods A systematic literature review of published articles reporting outcomes after nonsurgical and surgical management of spinal synovial cysts was performed. Results There were 51 published studies regarding the treatment of synovial cysts identified. Treatment modalities include observation, steroid injections, percutaneous cyst aspiration, hemilaminectomy or bilateral laminectomy with and without instrumented fusion, and minimally invasive cyst excision. Conclusions Based on review of the treatment modalities and outcomes, recommendations for the management of patients with synovial cysts are proposed. Observation can be considered in cases where there is no intractable pain. High-risk surgical patients with intractable pain may consider corticosteroid injection or percutaneous cyst aspiration; however, the failure rate of such a procedure approaches 50%. Patients with intractable pain are candidates for surgical resection of the symptomatic cyst. In cases of significant neurologic deficit, motor weakness, back pain, multiple synovial cysts, or spondylolisthesis, bilateral laminectomy and instrumented fusion may offer the best long-term outcome.