Benign Brain and Spinal Tumors Originating from Bone or Cartilage.

Benign osseocartilaginous tumors of the spine are overall uncommon, representing between 1 and 13% of all primary bone tumors and less than 10% of all spinal tumors. Tumors in this category include osteoblastic lesions such as the related osteoid osteoma and osteoblastoma, and cartilage-forming lesions including osteochondroma, chondroma, and chondroblastoma. Aneurysmal bone cysts, giant cell tumors of bone, and eosinophilic granulomas also comprise benign tumors of the spine arising from bone. There is significant heterogeneity in the epidemiology, molecular biology, imaging features, and optimal treatment of these lesions. For example, osteoid osteoma is characterized by high expression of the cyclooxygenase enzymes, making it amenable to treatment with anti-inflammatory drugs initially, whereas other lesions such as osteoblastoma may require intralesional curettage or en bloc resection sooner. Generally, en bloc resection is preferred when possible to minimize risk of recurrence. Further, some tumors may arise in the setting of syndromic conditions, such as multiple chondromas arising in Ollier disease or Maffucci syndrome, or as part of genetic disorders, such as osteochondromas in the context of hereditary multiple exostosis. These lesions may present with local pain, cause neurological compromise or be discovered incidentally on routine imaging. The Enneking classification and Weinstein-Boriani-Biagini system are routinely used to classify lesions and assist in surgical planning. More novel techniques such as radiofrequency ablation and laser photocoagulation have been applied for the treatment of osteoid osteoma and may have utility in the treatment of other lesion types. A multidisciplinary approach is critical in the management of benign lesions of the spine, and both chemotherapeutic and surgical approaches are routinely used.

Spatial Characteristics of Peripheral Visual Islands in Retinitis Pigmentosa.

Purpose: Retinitis pigmentosa (RP) is typified by progressive peripheral visual field (pVF) loss in patterns that can vary between individuals. Greater understanding of pVF preservation may inform research on therapeutic targets. However, characteristics of retained pVF are incompletely understood. We aimed to evaluate the spatial characteristics of retained pVF in RP. Methods: We developed a computational platform to generate a probability map of the spatial distribution of retained pVF loci using the Goldmann V4e isopter. RP subjects were grouped into cross-sectional and longitudinal datasets. Probability maps of retained pVF were generated for categories of symptomatic disease duration (SDD). We applied a mathematical model to determine the anatomical correlate of the retained pVF. Results: A total of 152 subjects were included. The mean age was 46.7 years. SDD was <20 years (47.4%), 20 to 40 years (39.5%), or >40 years (13.2%). Longitudinal data (3.2-5.7 years of follow up) were available for 65 subjects. In the cross-sectional dataset, retained pVF loci were most likely to be located between the 50° and 80° isoeccentric meridians and between the 30° to 50° radial axes. In the longitudinal dataset, inferotemporal pVF loci were the most likely to be preserved over time. The area of pVF retention corresponded anatomically to the pre-equatorial superonasal retina. Conclusions: Semiautomated quantitation of pVF may be a useful tool to analyze spatial characteristics of VF in RP. Retinal cells in the superonasal periphery may be resilient to RP-related functional decline. Understanding the cellular and molecular basis of pVF resilience in the retina may inform efforts to develop treatment modalities for RP.

Deployment of Clinical Prediction Models: A Practical Guide to Nomograms and Online Calculators.

The use of predictive models within neurosurgery is increasing and many models described in published journal articles are made available to readers in formats such as nomograms and online calculators. The present chapter details a step-by-step methodology with accompanying R code that may be used to implement models both in the form of traditional nomograms and as open-access, online calculators through RStudio's Shinyapps. The chapter assumes a basic understanding of predictive modeling in R and utilizes open-access files created by the Machine Intelligence in Clinical Neuroscience (MICN) Lab (Department of Neurosurgery and the Clinical Neuroscience Center of the University Hospital Zurich). When implemented correctly, tools such as nomograms and predictive calculators have the potential to improve user understanding of the underlying statistical models, facilitate broader adoption, and to streamline the eventual use of such models in clinical settings.

Overview of Algorithms for Natural Language Processing and Time Series Analyses.

A host of machine learning algorithms have been used to perform several different tasks in NLP and TSA. Prior to implementing these algorithms, some degree of data preprocessing is required. Deep learning approaches utilizing multilayer perceptrons, recurrent neural networks (RNNs), and convolutional neural networks (CNNs) represent commonly used techniques. In supervised learning applications, all these models map inputs into a predicted output and then model the discrepancy between predicted values and the real output according to a loss function. The parameters of the mapping function are then optimized through the process of gradient descent and backward propagation in order to minimize this loss. This is the main premise behind many supervised learning algorithms. As experience with these algorithms grows, increased applications in the fields of medicine and neuroscience are anticipated.

A Brief History of Machine Learning in Neurosurgery.

The history of machine learning in neurosurgery spans three decades and continues to develop at a rapid pace. The earliest applications of machine learning within neurosurgery were first published in the 1990s as researchers began developing artificial neural networks to analyze structured datasets and supervised tasks. By the turn of the millennium, machine learning had evolved beyond proof-of-concept; algorithms had success detecting tumors in unstructured clinical imaging, and unsupervised learning showed promise for tumor segmentation. Throughout the 2000s, the role of machine learning in neurosurgery was further refined. Well-trained models began to consistently best expert clinicians at brain tumor diagnosis. Additionally, the digitization of the healthcare industry provided ample data for analysis, both structured and unstructured. By the 2010s, the use of machine learning within neurosurgery had exploded. The rapid deployment of an exciting new toolset also led to the growing realization that it may offer marginal benefit at best over conventional logistical regression models for analyzing tabular datasets. Additionally, the widespread adoption of machine learning in neurosurgical clinical practice continues to lag until additional validation can ensure generalizability. Many exciting contemporary applications nonetheless continue to demonstrate the unprecedented potential of machine learning to revolutionize neurosurgery when applied to appropriate clinical challenges.

Impact of race on nonroutine discharge, length of stay, and postoperative complications after surgery for spinal metastases.

OBJECTIVE: Previous studies have suggested the possibility of racial disparities in surgical outcomes for patients undergoing spine surgery, although this has not been thoroughly investigated in those with spinal metastases. Given the increasing prevalence of spinal metastases requiring intervention, knowledge about potential discrepancies in outcomes would benefit overall patient care. The objective in the present study was to investigate whether race was an independent predictor of postoperative complications, nonroutine discharge, and prolonged length of stay (LOS) after surgery for spinal metastasis. METHODS: The authors retrospectively examined patients at a single comprehensive cancer center who had undergone surgery for spinal metastasis between April 2013 and April 2020. Demographic information, primary pathology, preoperative clinical characteristics, and operative outcomes were collected. Factors achieving p values < 0.15 on univariate regression were entered into a stepwise multivariable logistic regression to generate predictive models. Nonroutine discharge was defined as a nonhome discharge destination and prolonged LOS was defined as LOS greater than the 75th percentile for the entire cohort. RESULTS: Three hundred twenty-eight patients who had undergone 348 operations were included: 240 (69.0%) White and 108 (31.0%) Black. On univariable analysis, cohorts significantly differed in age (p = 0.02), marital status (p < 0.001), insurance status (p = 0.03), income quartile (p = 0.02), primary tumor type (p = 0.04), and preoperative Karnofsky Performance Scale (KPS) score (p < 0.001). On multivariable analysis, race was an independent predictor for nonroutine discharge: Black patients had significantly higher odds of nonroutine discharge than White patients (adjusted odds ratio [AOR] 2.24, 95% confidence interval [CI] 1.28-3.92, p = 0.005). Older age (AOR 1.06 per year, 95% CI 1.03-1.09, p < 0.001), preoperative KPS score ≤ 70 (AOR 3.30, 95% CI 1.93-5.65, p < 0.001), preoperative Frankel grade A-C (AOR 3.48, 95% CI 1.17-10.3, p = 0.02), insurance status (p = 0.005), being unmarried (AOR 0.58, 95% CI 0.35-0.97, p = 0.04), number of levels (AOR 1.17 per level, 95% CI 1.05-1.31, p = 0.004), and thoracic involvement (AOR 1.71, 95% CI 1.02-2.88, p = 0.04) were also predictive of nonroutine discharge. However, race was not independently predictive of postoperative complications or prolonged LOS. Higher Charlson Comorbidity Index (AOR 1.22 per point, 95% CI 1.04-1.43, p = 0.01), low preoperative KPS score (AOR 1.84, 95% CI 1.16-2.92, p = 0.01), and number of levels (AOR 1.15 per level, 95% CI 1.05-1.27, p = 0.004) were predictive of complications, while insurance status (p = 0.05), income quartile (p = 0.01), low preoperative KPS score (AOR 1.64, 95% CI 1.03-2.72, p = 0.05), and number of levels (AOR 1.16 per level, 95% CI 1.05-1.30, p = 0.004) were predictive of prolonged LOS. CONCLUSIONS: Race, insurance status, age, baseline functional status, and marital status were all independently associated with nonroutine discharge. This suggests that a combination of socioeconomic factors and functional status, rather than medical comorbidities, may best predict postdischarge disposition in patients treated for spinal metastases. Further investigation in a prospective cohort is merited.

Comparison of frailty metrics and the Charlson Comorbidity Index for predicting adverse outcomes in patients undergoing surgery for spine metastases.

OBJECTIVE: Frailty-the state defined by decreased physiological reserve and increased vulnerability to physiological stress-is exceedingly common in oncology patients. Given the palliative nature of spine metastasis surgery, it is imperative that patients be healthy enough to tolerate the physical insult of surgery. In the present study, the authors compared the association of two frailty metrics and the widely used Charlson Comorbidity Index (CCI) with postoperative morbidity in spine metastasis patients. METHODS: A retrospective cohort of patients who underwent operations for spinal metastases at a comprehensive cancer center were identified. Data on patient demographic characteristics, disease state, medical comorbidities, operative details, and postoperative outcomes were collected. Frailty was measured with the modified 5-item frailty index (mFI-5) and metastatic spinal tumor frailty index (MSTFI). Outcomes of interest were length of stay (LOS) greater than the 75th percentile of the cohort, nonroutine discharge, and the occurrence of ≥ 1 postoperative complication. RESULTS: In total, 322 patients were included (mean age 59.5 ± 12 years; 56.9% of patients were male). The mean ± SD LOS was 11.2 ± 9.9 days, 44.5% of patients had nonroutine discharge, and 24.0% experienced ≥ 1 postoperative complication. On multivariable analysis, increased frailty on mFI-5 and MSTFI was independently predictive of all three outcomes: prolonged LOS (OR 1.67 per point, 95% CI 1.06-2.63, p = 0.03; and OR 1.63 per point, 95% CI 1.29-2.05, p < 0.01, respectively), nonroutine discharge (OR 2.65 per point, 95% CI 1.74-4.04, p < 0.01; and OR 1.69 per point, 95% CI 1.36-2.11, p < 0.01), and ≥ 1 complication (OR 1.95 per point, 95% CI 1.23-3.09, p = 0.01; and OR 1.41 per point, 95% CI 1.12-1.77, p < 0.01). CCI was found to be independently predictive of only the occurrence of ≥ 1 postoperative complication (OR 1.45 per point, 95% CI 1.22-1.72, p < 0.01). CONCLUSIONS: Frailty measured with either mFI-5 or MSTFI scores was a more robust independent predictor of adverse postoperative outcomes than the more widely used CCI. Both mFI-5 and MSTFI were significantly associated with prolonged LOS, higher complication rates, and nonroutine discharge. Further investigation in a prospective multicenter cohort is merited.

Social media impact on qualitative performance metrics: Analysis and trends of top revenue grossing U.S. Hospitals.

Social media is a common, multi-purpose tool used by most hospitals to engage a broad audience. The relationship between hospital social media activity and performance on influential reputation and patient experience ratings is not well described. The aim of this study was to characterize social media activity across the top 100 revenue grossing U.S. hospitals and its impact on key patient experience and hospital rankings. While nearly all top 100 revenue grossing U.S. hospitals have a presence on social media, usage and following significantly varied. Social media activity metrics collected showed some limited association with reputation and patient experience-influenced rankings.

Influence of tranexamic acid use on venous thromboembolism risk in patients undergoing surgery for spine tumors.

OBJECTIVE: Patients with spine tumors are at increased risk for both hemorrhage and venous thromboembolism (VTE). Tranexamic acid (TXA) has been advanced as a potential intervention to reduce intraoperative blood loss in this surgical population, but many fear it is associated with increased VTE risk due to the hypercoagulability noted in malignancy. In this study, the authors aimed to 1) develop a clinical calculator for postoperative VTE risk in the population with spine tumors, and 2) investigate the association of intraoperative TXA use and postoperative VTE. METHODS: A retrospective data set from a comprehensive cancer center was reviewed for adult patients treated for vertebral column tumors. Data were collected on surgery performed, patient demographics and medical comorbidities, VTE prophylaxis measures, and TXA use. TXA use was classified as high-dose (≥ 20 mg/kg) or low-dose (< 20 mg/kg). The primary study outcome was VTE occurrence prior to discharge. Secondary outcomes were deep venous thrombosis (DVT) or pulmonary embolism (PE). Multivariable logistic regression was used to identify independent risk factors for VTE and the resultant model was deployed as a web-based calculator. RESULTS: Three hundred fifty patients were included. The mean patient age was 57 years, 53% of patients were male, and 67% of surgeries were performed for spinal metastases. TXA use was not associated with increased VTE (14.3% vs 10.1%, p = 0.37). After multivariable analysis, VTE was independently predicted by lower serum albumin (odds ratio [OR] 0.42 per g/dl, 95% confidence interval [CI] 0.23-0.79, p = 0.007), larger mean corpuscular volume (OR 0.91 per fl, 95% CI 0.84-0.99, p = 0.035), and history of prior VTE (OR 2.60, 95% CI 1.53-4.40, p < 0.001). Longer surgery duration approached significance and was included in the final model. Although TXA was not independently associated with the primary outcome of VTE, high-dose TXA use was associated with increased odds of both DVT and PE. The VTE model showed a fair fit of the data with an area under the curve of 0.77. CONCLUSIONS: In the present cohort of patients treated for vertebral column tumors, TXA was not associated with increased VTE risk, although high-dose TXA (≥ 20 mg/kg) was associated with increased odds of DVT or PE. Additionally, the web-based clinical calculator of VTE risk presented here may prove useful in counseling patients preoperatively about their individualized VTE risk.

Drivers of Readmission and Reoperation After Surgery for Vertebral Column Metastases.

OBJECTIVE: To determine those clinical, demographic, and operative factors that predict 30-day unplanned reoperation and readmission within a population of adults who underwent spinal metastasis surgery at a comprehensive cancer center. METHODS: Adults who underwent spinal metastasis surgery at a comprehensive cancer center were analyzed. Data included baseline laboratory values, cancer history, demographics, operative characteristics and medical comorbidities. Medical comorbidities were quantified using the modified Charlson Comorbidity Index (CCI). Values associated with the outcomes of interest were then subjected to multivariable logistic regression to identify independent predictors of readmission and reoperation. RESULTS: A total of 345 cases were identified. Mean age was 59.4 ± 11.7 years, 56% were male, and the racial makeup was 64% white, 29% black, and 7.3% other. Forty-two patients (12.2%) had unplanned readmissions, most commonly for wound infection with dehiscence (14.2%), venous thromboembolism (14.2%), and bowel obstruction/complication (11.9%). Thirteen patients required reoperation (4%), most commonly for wound infection with dehiscence (39%) or local recurrence (23%). Multivariable analysis showed that the modified CCI (odds ratio [OR], 1.25; 95% confidence interval [CI] 1.03-1.52; P = 0.03) was an independent predictor of 30-day readmission. Independent predictors of 30-day unplanned reoperation were: black (vs. white) race (OR, 0.08; 95% CI, 0.01-0.41; P < 0.01), length of stay (OR, 1.05 per day; 95% CI, 1.00-1.09; P = 0.04), and CCI (OR, 1.72 per point; 95% CI, 1.29-2.28; P < 0.01). CONCLUSIONS: Increasing medical comorbidities is independently predictive of both 30-day unplanned readmission and reoperation after spinal metastasis surgery. Unplanned reoperation is also positively predicted by a longer index admission. Neither tumor pathology nor age predicted outcome, suggesting that poor wound-healing factors and increased surgical morbidity may best predict these adverse outcomes.

Interrater and Intrarater Reliability of the Vertebral Bone Quality Score.

BACKGROUND: Vertebral bone quality had a significant impact on postoperative outcomes in spinal fusion surgery. New magnetic resonance imaging-based measures, such as the Vertebral Bone Quality (VBQ) score, may allow for bone quality assessment without the radiation associated with conventional testing. In the present study, we sought to assess the intrarater and interrater reliability of VBQ scores calculated by medical professionals and trainees. METHODS: Thirteen reviewers of various specialties and levels of training were recruited and asked to calculate VBQ scores for 30 patients at 2 time points separated by 2 months. Scored volumes were acquired from patients treated for both degenerative and oncologic indications. Intrarater and interrater agreement, quantified by intraclass correlation coefficient (ICC), was assessed using 2-way random effects modeling. Square-weight Cohen κ and Kendall Tau-b were used to determine whether raters assigned similar scores during both evaluations. RESULTS: All raters showed moderate to excellent reliability for VBQ score (ICC 0.667-0.957; κ0.648-0.921) and excellent reliability for all constituent components used to calculate VBQ score (ICC all ≥0.97). Interrater reliability was also found to be good for VBQ score on both the first (ICC = 0.818) and second (ICC = 0.800) rounds of assessment; scores for the constituent component all had ICC values ≥0.97 for the constituent components. CONCLUSIONS: The VBQ score appears to have both good intrarater and interrater reliability. In addition, there appeared to be no correlation between score reliability and level of training. External validation and further investigations of its ability to accurately model bone biomechanical properties are necessary.

Plastic surgery wound closure following resection of spinal metastases.

OBJECTIVE: Surgical site infection and dehiscence are devastating complications of surgery for spinal metastases. Wound closure involving plastic surgeons has been proposed as a strategy to lower post-operative complications. Here we investigated whether plastic surgery closure is associated with lower rates of wound complications, wound infection, and wound reoperation compared to simple closure by spine surgeons. METHODS: Patients surgically treated for metastatic tumors at a single comprehensive cancer center between April 2013-2020 were retrospectively identified. Primary pathology, demographic information, clinical characteristics, pre-operative laboratory values, tumor location, operative characteristics, and post-operative outcomes were collected. Univariable analyses used student t-tests for continuous variables and χ2 tests for categorical variables. Multivariable regressions were performed to control for confounders. RESULTS: We included 317 patients, of which 56 underwent closure by plastic surgeons and 291 by neurosurgeons. Patients in the plastic surgery cohort were more likely to have received prior radiation to the surgical site, more often on long-term corticosteroid therapy, and more likely to have sacrococcygeal tumors. Operations involving plastic surgeons were more likely to be revision surgeries, corpectomies, and to involve a staged approach. Additionally, patients in the plastic surgery cohort had longer incision lengths, longer surgeries, greater intraoperative blood loss (IOBL), were more likely to receive transfusions, and had longer hospitalizations. Local paraspinous advancement flaps were the most common complex wound closure technique. Plastic surgery closure was not significantly associated with a difference in rates of post-operative wound complications, wound infection, or wound-related reoperations compared to simple wound closure. CONCLUSION: We identified that patients undergoing plastic surgery wound closure had worse baseline risk, longer surgeries, greater IOBL, and longer hospitalizations compared to patients receiving simple closure. Despite their increased risk, complex wound closure did not significantly alter the rates of post-operative wound complications, wound infection, or wound-related reoperations. Consideration may be given to plastic surgery closure in patients at high risk of wound complications or with extensive wound defects.

Impact of Multidisciplinary Intraoperative Teams on Thirty-Day Complications After Sacral Tumor Resection.

OBJECTIVE: To evaluate the impact of multidisciplinary intraoperative teams on surgical complications in patients undergoing sacral tumor resection. METHODS: We reviewed all patients with primary or metastatic sacral tumors managed at a single comprehensive cancer center over a 7-year period. Perioperative complication rates were compared between those treated by an unassisted spinal oncologist and those treated with the assistance of at least 1 other surgical specialty. Statistical analysis involved univariable and stepwise multivariable logistic regression models to identify predictors of multidisciplinary management and 30-day complications. RESULTS: A total of 107 patients underwent 132 operations for sacral tumors; 92 operations involved multidisciplinary teams, including 54% of metastatic tumor operations and 74% of primary tumor operations. Patients receiving multidisciplinary management had higher body mass indexes (29.8 vs. 26.3 kg/m2; P = 0.008), larger tumors (258 vs. 55 cm³; P < 0.001), and higher American Society of Anesthesiologists scores (3 vs. 2; P = 0.049). Only larger tumor volume (odds ratio [OR], 1.007 per cm³; P < 0.001) and undergoing treatment for a malignant primary versus a metastatic tumor (OR, 23.4; P < 0.001) or benign primary tumor (OR, 29.3; P < 0.001) were predictive of multidisciplinary management. Although operations involving multidisciplinary teams were longer (467 vs. 231 minutes; P < 0.001) and had higher blood loss (1698 vs. 774 mL; P = 0.004), 30-day complication rates were similar (37 vs. 27%; P = 0.39). On multivariable analysis, only larger tumor volume (OR, 1.004 per cm³; P = 0.005) and longer surgical duration (OR, 1.002 per minute; P = 0.03) independently predicted higher 30-day complications. CONCLUSIONS: Although patients managed with multidisciplinary teams had larger tumors and worse baseline health, 30-day complications were similar. This finding suggests that the use of multidisciplinary teams may help to mitigate surgical morbidity in those with high baseline risk.

Radiotherapy and Surgical Advances in the Treatment of Metastatic Spine Tumors: A Narrative Review.

Spine tumors encompass a wide range of diseases with a commensurately broad spectrum of available treatments, ranging from radiation for spinal metastases to highly invasive en bloc resection for primary vertebral column malignancies. This high variability in treatment approaches stems both from variability in the goals of surgery (e.g., oncologic cure vs. symptom palliation) and from the significant advancements in surgical technologies that have been made over the past 2 decades. Among these advancements are improvements in surgical technique, namely minimally invasive approaches, increased availability of focused radiation modalities (e.g., proton therapy and linear accelerator devices), and new surgical technologies, such as carbon fiber-reinforced polyether ether ketone rods. In addition, several groups have described nonsurgical interventions, such as vertebroplasty and kyphoplasty for spinal instability secondary to pathologic fracture, and lesion ablation with spinal laser interstitial thermoablation, radiofrequency ablation, or cryoablation. We provide an overview of the latest technological advancements in spinal oncology and their potential usefulness for modern spinal oncologists.

Fenestrated pedicle screws for thoracolumbar instrumentation in patients with poor bone quality: Case series and systematic review of the literature.

OBJECTIVE: To describe the results of a single-surgeon series and systematically review the literature on cement-augmented instrumented fusion with fenestrated pedicle screws. METHODS: All patients treated by the senior surgeon using fenestrated screws between 2017 and 2019 with a minimum of 6-months of clinical and radiographic follow-up were included. For the systematic review, we used PRISMA guidelines to identify all prior descriptions of cement-augmented instrumented fusion with fenestrated pedicle screws in the English literature. Endpoints of interest included hardware loosening, cement leakage, and pulmonary cement embolism (PCE). RESULTS: Our series included 38 patients (mean follow-up 14.8 months) who underwent cement-augmented instrumentation for tumor (47.3%), deformity/degenerative disease (39.5%), or osteoporotic fracture (13.2%). Asymptomatic screw lucency was seen in 2.6%, cement leakage in 445, and pulmonary cement embolism (PCE) in 5.2%. Our literature review identified 23 studies (n = 1526 patients), with low reported rates of hardware loosening (0.2%) and symptomatic PCE (1.0%). Cement leakage, while common (55.6%), produced symptoms in fewer than 1% of patients. Indications for cement-augmentation in this cohort included: spine metastasis with or without pathologic fracture (n = 18; 47.3%), degenerative spine disease or fixed deformity with poor underlying bone quality (n = 15; 39.5%), and osteoporotic fracture (n = 5; 13.2%). CONCLUSION: Cement-augmented fusion with fenestrated screws appears to be a safe, effective means of treating patients with poor underlying bone quality secondary to tumor or osteoporosis. High-quality evidence with direct comparisons to non-augmented patients is needed.

Sacrectomy for sacral tumors: perioperative outcomes in a large-volume comprehensive cancer center.

BACKGROUND CONTEXT: Sacral tumors are incredibly rare lesions affecting fewer than one in every 10,000 persons. Reported perioperative morbidity rates range widely, varying from 30% to 70%, due to the relatively low volumes seen by most centers. Factors affecting perioperative outcome following sacrectomy remain ill-defined. PURPOSE: To characterize perioperative outcomes of sacral tumor patients undergoing sacrectomy and identify independent risk factors of perioperative morbidity STUDY DESIGN/SETTING: Retrospective cohort study at a single comprehensive cancer center PATIENT SAMPLE: Consecutively treated sacral tumor patients (primary or metastatic) undergoing sacrectomy for oncologic resection between April 2013 and April 2020 OUTCOME MEASURES: Perioperative complications, hospital length of stay, non-home discharge, 30-day readmission, and 30-day reoperation METHODS: Details were gathered about tumor pathology and morphology, surgery performed, baseline medical comorbidities, preoperative lab data, and patient demographics. Stepwise multivariable regressions were conducted to identify independent risk factors of perioperative outcomes while evaluating predictive accuracy. RESULTS: 57 sacral tumor patients were included (mean age 55.5±13.0 years; 60% female). The complication, non-home discharge, 30-day readmission, and 30-day reoperation rates were 39%, 56%, 16%, and 14%, respectively. Independent predictors of perioperative complications included ASA>2 (OR=10.7; 95%CI [1.3, 86.0]; p=0.026), radicular pain (OR=10.9; p=0.014), platelet count (OR=0.989 per 10³/µL; p=0.049), and instrumentation (OR=10.7; p=0.009). Independent predictors of length of stay included iliac vessel involvement (ß=15.8; p=0.005), larger tumor volume (ß=0.027 per cm³; p<0.001), a staged procedure (ß=10.0; p=0.018), and S1 nerve root sacrifice (OR=15.8; p=.011). The optimal model predictive of non-home discharge included bilateral S3-S5 or higher nerve root sacrifice (OR=3.9; p=0.054), instrumentation (OR=8.6; p=0.005), and vertical rectus abdominis musculocutaneous flap closure (OR=5.3; p=0.067). 30-day readmission was independently predicted by history of chronic kidney disease (OR=26.7; p=0.021), radicular pain (OR=8.1; p=0.039), and preoperative saddle anesthesia (OR=12.6; p=0.026). All multivariable models achieved good discrimination (AUC>0.8 and R2>0.7). CONCLUSION: Clinical and operative factors were important predictors of complications and 30-day readmission, while tumor-related and operative factors accounted for most of the variability in length of stay and non-home discharge.

Web-Based Calculator Predicts Surgical-Site Infection After Thoracolumbar Spine Surgery.

BACKGROUND: Surgical-site infection (SSI) after spine surgery leads to increased length of stay, reoperation, and worse patient quality of life. We sought to develop a web-based calculator that computes an individual's risk of a wound infection following thoracolumbar spine surgery. METHODS: We performed a retrospective review of consecutive patients undergoing elective degenerative thoracolumbar spine surgery at a tertiary-care institution between January 2016 and December 2018. Patients who developed SSI requiring reoperation were identified. Regression analysis was performed and model performance was assessed using receiver operating curve analysis to derive an area under the curve. Bootstrapping was performed to check for overfitting, and a Hosmer-Lemeshow test was employed to evaluate goodness-of-fit and model calibration. RESULTS: In total, 1259 patients were identified; 73% were index operations. The overall infection rate was 2.7%, and significant predictors of SSI included female sex (odds ratio [OR] 3.0), greater body mass index (OR 1.1), active smoking (OR 2.8), worse American Society of Anesthesiologists physical status (OR 2.1), and greater surgical invasiveness (OR 1.1). The prediction model had an optimism-corrected area under the curve of 0.81. A web-based calculator was created: https://jhuspine2.shinyapps.io/Wound_Infection_Calculator/. CONCLUSIONS: In this pilot study, we developed a model and simple web-based calculator to predict a patient's individualized risk of SSI after thoracolumbar spine surgery. This tool has a predictive accuracy of 83%. Through further multi-institutional validation studies, this tool has the potential to alert both patients and providers of an individual's SSI risk to improve informed consent, mitigate risk factors, and ultimately drive down rates of SSIs.

Low-Intensity Pulsed Ultrasound as a Potential Adjuvant Therapy to Promote Spinal Fusion: Systematic Review and Meta-analysis of the Available Data.

Despite extensive research, nonunion continues to affect a nontrivial proportion of patients undergoing spinal fusion. Recently, preclinical studies have suggested that low-intensity pulsed ultrasound (LIPUS) may increase rates of spinal fusion. In this study, we summarized the available in vivo literature evaluating the effect of LIPUS on spinal fusion and performed a meta-analysis of the available data to estimate the degree to which LIPUS may mediate higher fusion rates. Across 13 preclinical studies, LIPUS was associated with a 9-fold increase in the odds of successful spinal fusion. Future studies are necessary to establish the benefit of LIPUS on spinal fusion in clinical populations.

Vertebral bone quality score predicts fragility fractures independently of bone mineral density.

BACKGROUND: Current evidence suggests that dual-energy x-ray absorptiometry (DXA) scans, the conventional method defining osteoporosis, is underutilized and, when used, may underestimate patient risk for skeletal fragility. It has recently been suggested that other imaging modalities may better estimate bone quality, such as the magnetic resonance imaging (MRI)-based vertebral bone quality (VBQ) score which also may assess vertebral compression fracture risk in patients with spine metastases. PURPOSE: To evaluate whether VBQ score is predictive of fragility fractures in a population with pre-existing low bone density and at high-risk for fracture. STUDY DESIGN/SETTING: Retrospective single-center cohort. PATIENT SAMPLE: Patients followed at a metabolic bone clinic for osteopenia and/or osteoporosis. OUTCOME MEASURES: Radiographically-documented new-onset fragility fracture. METHODS: Patients with a DXA and MRI scans at the time of consultation and ≥2-year follow-up were included. Details were gathered about patient demographics, health history, current medication use, and serological studies of kidney function and bone turnover. For each patient, VBQ score was calculated using T1-weighted lumbar MRI images. Univariable and multivariable analyses were used to identify the independent predictors of a new fragility fracture. To support the construct validity of VBQ, patient VBQ scores were compared to those in a cohort of 45 healthy adults. RESULTS: Seventy-two (39.1%) study participants suffered fragility fractures, the occurrence of which was associated with higher VBQ score (3.50 vs. 3.01; p<.001), chronic glucocorticoid use (30.6% vs. 15.2%; p=.014), and a history of prior fragility fracture (36.1% vs. 21.4%; p=.030). Mean VBQ score across all patients in the study cohort was significantly higher than the mean VBQ score in the healthy controls (p<.001). In multivariable analysis, new-onset fracture was independently associated with history of prior fracture (OR=6.94; 95% confidence interval [2.48-19.40]; p<.001), higher VBQ score (OR=2.40 per point; [1.30-4.44]; p=.003), higher body mass index (OR=1.09 per kg/m²; [1.01-1.17]; p=.03), and chronic glucocorticoid use (OR=2.89; [1.03-8.17]; p=0.043). Notably, DXA bone mineral density (BMD) was not found to be significantly predictive of new-onset fractures in the multivariable analysis (p=.081). CONCLUSIONS: Here we demonstrate the novel, MRI-derived VBQ score is both an independent predictor of fragility fracture in at-risk patients and a superior predictor of fracture risk than DXA-measured BMD. Given the frequency with which MRIs are obtained by patients undergoing spine surgery consultation, we believe the VBQ score could be a valuable tool for estimating bone quality in order to optimize the management of these patients.

Assessing underlying bone quality in spine surgery patients: a narrative review of dual-energy X-ray absorptiometry (DXA) and alternatives.

Poor bone quality and low bone mineral density (BMD) have been previously tied to higher rates of postoperative mechanical complications in patients undergoing spinal fusion. These include higher rates of proximal junctional kyphosis, screw pullout, pseudoarthrosis, and interbody subsidence. For these reasons, accurate preoperative assessment of a patient's underlying bone quality is paramount for all elective procedures. Dual-energy X-ray absorptiometry (DXA) is currently considered to be the gold standard for assessing BMD. However, a growing body of research has suggested that in vivo assessments of BMD using DXA are inaccurate and have, at best, moderate correlations to postoperative mechanical complications. Consequently, there have been investigations into using alternative methods for assessing in vivo bone quality, including using computed tomography (CT) and magnetic resonance imaging (MRI) volumes that are commonly obtained as part of surgical evaluation. Here we review the data regarding the accuracy of DXA for the evaluation of spine bone quality and describe the alternative imaging modalities currently under investigation.