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Study Design: Retrospective Cohort Objective: Antiresorptive drugs are often given to minimize fracture risk for bone metastases, but data regarding optimal time or ability to reduce stereotactic body radiotherapy (SBRT)-induced fracture risk is limited. This study examines the association between antiresorptive use surrounding spinal SBRT and vertebral compression fracture (VCF) incidence to provide information regarding effectiveness and optimal timing of use. Methods: Patients treated with SBRT for spinal metastases at a single institution between 2009-2020 were included. Kaplan-Meier analysis was used to compare cumulative incidence of VCF for those taking antiresorptive drugs pre-SBRT, post-SBRT only, and none at all. Cox proportional hazards and Fine-Gray competing risk models were used to identify additional factors associated with VCF. Results: Of the 234 patients (410 vertebrae) analyzed, 49 (20.9%) were taking bisphosphonates alone, 42 (17.9%) were taking denosumab alone, and 25 (10.7%) were taking both. Kaplan-Meier analysis revealed a statistically significant lower VCF incidence for patients initiating antiresorptive drugs before SBRT compared to those taking none at all (4% vs 12% at 1 year post-SBRT, P =.045; and 4% vs 23% at 2 years, P =.008). On multivariate analysis, denosumab duration (HR:.87, P =.378) or dose (HR: 1.00, P =.644) as well as bisphosphonate duration (HR:.98, P =.739) or dose (HR:.99, P =.741) did not have statistical significance on VCF incidence. Conclusion: Initiating antiresorptive agents before SBRT may reduce the risk of treatment-induced VCF. Antiresorptive drugs are underutilized in patients with spine metastases and may represent a useful intervention to minimize toxicity and improve long-term outcomes. [ABSTRACT FROM AUTHOR]

Background: Cone‐beam CT (CBCT) with non‐circular scanning orbits can improve image quality for 3D intraoperative image guidance. However, geometric calibration of such scans can be challenging. Existing methods typically require a prior image, specialized phantoms, presumed repeatable orbits, or long computation time. Purpose: We propose a novel fully automatic online geometric calibration algorithm that does not require prior knowledge of fiducial configuration. The algorithm is fast, accurate, and can accommodate arbitrary scanning orbits and fiducial configurations. Methods: The algorithm uses an automatic initialization process to eliminate human intervention in fiducial localization and an iterative refinement process to ensure robustness and accuracy. We provide a detailed explanation and implementation of the proposed algorithm. Physical experiments on a lab test bench and a clinical robotic C‐arm scanner were conducted to evaluate spatial resolution performance and robustness under realistic constraints. Results: Qualitative and quantitative results from the physical experiments demonstrate high accuracy, efficiency, and robustness of the proposed method. The spatial resolution performance matched that of our existing benchmark method, which used a 3D‐2D registration‐based geometric calibration algorithm. Conclusions: We have demonstrated an automatic online geometric calibration method that delivers high spatial resolution and robustness performance. This methodology enables arbitrary scan trajectories and should facilitate translation of such acquisition methods in a clinical setting. [ABSTRACT FROM AUTHOR]

Ultrasound technology can provide high-resolution imaging of blood flow following spinal cord injury (SCI). Blood flow imaging may improve critical care management of SCI, yet its duration is limited clinically by the amount of contrast agent injection required for high-resolution, continuous monitoring. In this study, we aim to establish non-contrast ultrasound as a clinically translatable imaging technique for spinal cord blood flow via comparison to contrast-based methods and by measuring the spatial distribution of blood flow after SCI. A rodent model of contusion SCI at the T12 spinal level was carried out using three different impact forces. We compared images of spinal cord blood flow taken using both non-contrast and contrast-enhanced ultrasound. Subsequently, we processed the images as a function of distance from injury, yielding the distribution of blood flow through space after SCI, and found the following. (1) Both non-contrast and contrast-enhanced imaging methods resulted in similar blood flow distributions (Spearman's ρ = 0.55, p < 0.0001). (2) We found an area of decreased flow at the injury epicenter, or umbra (p < 0.0001). Unexpectedly, we found increased flow at the periphery, or penumbra (rostral, p < 0.05; caudal, p < 0.01), following SCI. However, distal flow remained unchanged, in what is presumably unaffected tissue. (3) Finally, tracking blood flow in the injury zones over time revealed interesting dynamic changes. After an initial decrease, blood flow in the penumbra increased during the first 10 min after injury, while blood flow in the umbra and distal tissue remained constant over time. These results demonstrate the viability of non-contrast ultrasound as a clinical monitoring tool. Furthermore, our surprising observations of increased flow in the injury periphery pose interesting new questions about how the spinal cord vasculature reacts to SCI, with potentially increased significance of the penumbra. [ABSTRACT FROM AUTHOR]

Acute spinal cord injury (SCI) requires prompt diagnosis and intervention to minimize the risk of permanent neurologic deficit. Presently, SCI diagnosis and interventional planning rely on magnetic resonance imaging (MRI), which is not always available or feasible for severely injured patients. Detection of disease-specific biomarkers in biofluids via liquid biopsy may provide a more accessible and objective means of evaluating patients with suspected SCI. Cell-free DNA, which has been used for diagnosing and monitoring oncologic disease, may detect damage to spinal cord neurons via tissue-specific methylation patterns. Other types of biomarkers, including proteins and RNA species, have also been found to reflect neuronal injury and may be included as part of a multi-analyte assay to improve liquid biopsy performance. The feasibility of implementing liquid biopsy into current practices of SCI management is supported by the relative ease of blood sample collection as well as recent advancements in droplet digital polymerase chain reaction technology. In this review, we detail the current landscape of biofluid biomarkers for acute SCI and propose a framework for the incorporation of a putative blood test into the clinical management of SCI. [ABSTRACT FROM AUTHOR]

Background: Incidental intradural tumors of the spine in the pediatric population are rare lesions whose management remains unclear. Surgeons must balance the risks of iatrogenic deficits and complications after surgical resection against the risks from progressive growth of the tumor. Moreover, the natural history of an incidental finding can be difficult to predict. Here, we review the literature on incidental intradural tumors of the spine and present considerations for their management. Summary: Growth of the tumor or changes in radiographic features are usually indications for resection. Asymptomatic lesions can be found in patients with genetic syndromes that predispose to tumor formation, such as neurofibromatosis type 1 and 2, schwannomatosis, and Von-Hippel-Lindau syndrome, and careful workup of a genetic cause is warranted in any patient presenting with multiple tumors and/or cutaneous features. Close follow-up is generally favored given the heavy tumor burden; however, some recommend pre-emptive resection to prevent permanent neurological deficits. Incidental intradural tumors can also occur in association with hydrocephalus, significant syringomyelia, and cord compression, and surgical treatment is usually warranted. Tumors may also be discovered as part of the workup for scoliosis, where they are not truly incidental to the scoliosis but rather are contributing to curve deformation. Key Messages: Thorough workup of patients for associated genetic syndromes or comorbidities should be undertaken in pediatric patients with incidental intradural tumors. Further research is needed into the natural history of these incidental lesions. Incidental tumors can often be managed conservatively with close follow-up, with surgical intervention warranted for expanding tumors or new-onset symptoms. [ABSTRACT FROM AUTHOR]

The letter responds to a recent publication in the Global Spine Journal by Fushimi et al. The authors express agreement with the importance of occupying as much of the interbody space with a cage as possible to minimize the risk of subsidence and increase the rate of arthrodesis. However, they raise concerns about the authors' claim that their study is the first to biomechanically evaluate TLIF using double banana-shaped cages, as they reported similar findings in their own study. The authors invite Fushimi and colleagues to review their resources on the technical nuances of the nested interbody technique. They commend Fushimi and colleagues for advancing the transforaminal interbody technique and emphasize the need to optimize patient outcomes and minimize complications. [Extracted from the article]

This document is a response to a letter discussing a study on the use of antiresorptive medications prior to stereotactic body radiotherapy (SBRT) for spinal metastasis. The authors address questions raised in the letter, including the higher risk of vertebral compression fracture (VCF) in patients receiving antiresorptive therapy after SBRT. While the difference in VCF incidence was not found to be statistically significant, the authors speculate that patients who develop fractures may be more likely to receive antiresorptive agents. The document also clarifies components of the statistical analysis and emphasizes the need for larger datasets and prospective studies to confirm the findings. [Extracted from the article]

Objective: Monitoring microcirculation and visualizing microvasculature are critical for providing diagnosis to medical professionals and guiding clinical interventions. Ultrasound provides a medium for monitoring and visualization; however, there are challenges due to the complex microscale geometry of the vasculature and difficulties associated with quantifying perfusion. Here, we studied established and state‐of‐the‐art ultrasonic modalities (using six probes) to compare their detection of slow flow in small microvasculature. Methods: Five ultrasonic modalities were studied: grayscale, color Doppler, power Doppler, superb microvascular imaging (SMI), and microflow imaging (MFI), using six linear probes across two ultrasound scanners. Image readability was blindly scored by radiologists and quantified for evaluation. Vasculature visualization was investigated both in vitro (resolution and flow characterization) and in vivo (fingertip microvasculature detection). Results: Superb Microvascular Imaging (SMI) and Micro Flow Imaging (MFI) modalities provided superior images when compared with conventional ultrasound imaging modalities both in vitro and in vivo. The choice of probe played a significant difference in detectability. The slowest flow detected (in the lab) was 0.1885 ml/s and small microvasculature of the fingertip were visualized. Conclusions: Our data demonstrated that SMI and MFI used with vascular probes operating at higher frequencies provided resolutions acceptable for microvasculature visualization, paving the path for future development of ultrasound devices for microcirculation monitoring. [ABSTRACT FROM AUTHOR]

Simple Summary: Glioblastoma (GBM) is a common primary brain tumor with a short median overall survival despite aggressive treatment with resection, chemotherapy, and radiation therapy. Focused ultrasound (FUS) represents a promising new therapeutic approach for treatment of GBM. Unlike imaging forms of ultrasound, FUS can successfully penetrate the skull surrounding the brain, allowing for non-invasive ablation of tumor tissue. FUS can also temporarily disrupt the blood–brain barrier, a microvascular network that prohibits diffusion of most therapeutic agents, allowing chemotherapeutic drugs to penetrate the tumor. Other modalities are under investigation and include means of stimulating the immune system and sensitizing tumors to radiation therapy. The feasibility and safety of transcranial FUS has been illustrated in animal models and clinical trials. Precise results can be obtained under guidance from magnetic resonance imaging, limiting side effects. Successful outcomes from clinical trials will likely continue to motivate investigation and innovation of FUS technology for GBM. Glioblastoma (GBM) is an aggressive primary astrocytoma associated with short overall survival. Treatment for GBM primarily consists of maximal safe surgical resection, radiation therapy, and chemotherapy using temozolomide. Nonetheless, recurrence and tumor progression is the norm, driven by tumor stem cell activity and a high mutational burden. Focused ultrasound (FUS) has shown promising results in preclinical and clinical trials for treatment of GBM and has received regulatory approval for the treatment of other neoplasms. Here, we review the range of applications for FUS in the treatment of GBM, which depend on parameters, including frequency, power, pulse duration, and duty cycle. Low-intensity FUS can be used to transiently open the blood–brain barrier (BBB), which restricts diffusion of most macromolecules and therapeutic agents into the brain. Under guidance from magnetic resonance imaging, the BBB can be targeted in a precise location to permit diffusion of molecules only at the vicinity of the tumor, preventing side effects to healthy tissue. BBB opening can also be used to improve detection of cell-free tumor DNA with liquid biopsies, allowing non-invasive diagnosis and identification of molecular mutations. High-intensity FUS can cause tumor ablation via a hyperthermic effect. Additionally, FUS can stimulate immunological attack of tumor cells, can activate sonosensitizers to exert cytotoxic effects on tumor tissue, and can sensitize tumors to radiation therapy. Finally, another mechanism under investigation, known as histotripsy, produces tumor ablation via acoustic cavitation rather than thermal effects. [ABSTRACT FROM AUTHOR]

Background and objective: Comparative effectiveness research plays a vital role in health care delivery. Specialty training is one of these variables; surgeons who are trained in different specialties may have different outcomes performing the same procedure. The objective of this study was to investigate the impact of spine surgeon specialty (neurosurgery vs orthopedic surgery) on early perioperative outcome measures of elective posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS). Methods: This is a retrospective, 1:4 propensity score-matched cohort study. 5520 AIS patients were reviewed from ACS-NSQIP pediatric database. Propensity score matching was utilized. Results: Patients operated on by orthopedic surgeons were more likely to have shorter operation time (263 min vs 285 min), shorter total hospital stay (95 h vs 118 h), lower rate of return to operating room within the same admission (1.2% vs 3.8%), lower discharge rates after postoperative day 4 (23.8% vs 30.9%), and lower unplanned readmission rate (1.6% vs 4.1%), (p < 0.05). On the other hand, patients operated on by neurosurgeons had lower perioperative blood transfusion rate (62.1% vs 69.8%), (p < 0.05). Other outcome measures and mortality rates were not significantly different between the two cohorts. Conclusions: This retrospective study found significant differences in early perioperative outcomes of patients undergoing PSF for AIS by neurosurgeons and orthopedic surgeons. Further studies are recommended to corroborate this finding which may trigger changes in the educational curriculum for neurosurgery residents. [ABSTRACT FROM AUTHOR]

Efforts to develop effective neuroprotective therapies for ischemic stroke have had little success to date. One promising approach to neuroprotection is ischemic postconditioning, which utilizes brief bouts of ischemia after acute ischemic stroke to elicit neuroprotection, although the mechanism is largely unknown. As the primary components of transient ischemia are local hypoxia and acidosis, and hypoxic postconditioning has had little success, it is possible that the acidosis component may be the primary driver. To address the evidence behind this, we performed a systematic review of preclinical studies focused on the neuroprotective role of transient acidosis after ischemia. Animal studies demonstrated that mild-to-moderate acidosis after ischemic events led to better functional neurologic outcomes with reduced infarct volumes, while severe acidosis often led to cerebral edema and worse functional outcomes. In vitro studies demonstrated that mild-to-moderate acidosis improves neuronal survival largely through two means: (1) inhibition of harmful superoxide formation in the excitotoxic pathway and (2) remodeling neuronal mitochondria to allow for efficient ATP production (i.e., oxidative phosphorylation), even in the absence of oxygen. Similar to the animal studies, acidotic postconditioning in humans would entail short cycles of carbon dioxide inhalation, which has already been demonstrated to be safe as part of a hypercapnic challenge when measuring cerebrovascular reactivity. Due to the preclinical efficacy of acidotic postconditioning, its relatively straightforward translation into humans, and the growing need for neuroprotective therapies, future preclinical studies should focus on filling the current knowledge gaps that are currently restricting the development of phase I/II clinical trials. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Augmented reality (AR) navigation refers to novel technologies that superimpose images, such as radiographs and navigation pathways, onto a view of the operative field. The development of AR navigation has focused on improving the safety and efficacy of neurosurgical and orthopedic procedures. In this review, the authors focus on 3 types of AR technology used in spine surgery: AR surgical navigation, microscope-mediated heads-up display, and AR head-mounted displays. Microscope AR and head-mounted displays offer the advantage of reducing attention shift and line-of-sight interruptions inherent in traditional navigation systems. With the U.S. Food and Drug Administration's recent clearance of the XVision AR system (Augmedics, Arlington Heights, IL), the adoption and refinement of AR technology by spine surgeons will only accelerate. [ABSTRACT FROM AUTHOR]

Background: Concussion in American football, and specifically the National Football League (NFL) is a major area of interest and key focus for injury prevention. Complete and accurate characterization of when, how, and to whom these injuries occur can facilitate injury reduction efforts. Existing studies of concussion in the NFL use publicly available data, potentially limiting data quality and the inferences that can be made. Hypothesis: Concussion incidence in the NFL decreased across the 2015-2019 seasons. Study Design: Descriptive epidemiology study. Level of Evidence: Level 4. Methods: Concussion incidence, including counts, one-season risk, and rates per game and player-plays, among active NFL players from 2015 to 2019 is described by year, season, play type, and roster position. Results: A total 1302 concussions were identified from 2015 to 2019 among 1004 players. Of these, 80% occurred in NFL games. The average annual incidence of in-season game concussions changed over the study period, from 230.7 per season (2015-2017) to 177.0 per season (2018-2019); this represented a 23% decrease in game settings (P < 0.01). Practice concussions fluctuated across the years of the study from 38 to 67 per season (average = 50.8/season). There were 70.6 concussions per 100 preseason games, which was slightly higher than the regular season rate per game of 61.7. Overall, there were 790 regular season game concussions across 4,657,243 player-plays and 114,428 player-games during the 5-year study. In regular season games, the majority of concussions were sustained on running and passing plays (n = 119/season), and the highest average rate per play occurred on kickoffs (0.69/100 plays). Defensive secondary (cornerbacks, safeties, and generic defensive backs) and offensive line incurred the most concussions, and the highest rates of concussion were among tight ends and wide receivers. Conclusion and Relevance: Concussions in the NFL are a key focus for player safety. Concussion reduction strategies were implemented before 2018, after which there was a sustained 2-year decrease in concussion incidence, providing a new benchmark from which to work toward further injury reduction. [ABSTRACT FROM AUTHOR]

There are potential pitfalls associated with the pursuit of accurate surgical navigation, such as vulnerability of the reference array to accidental dislodgment and damage or soiling of tracking arrays on tools. Additionally, there are hazards encountered when attempting accurate robotic screw placement in spine surgery, including skiving of the tool on bone, displacement of the robotic arm, or patient movement. Proven techniques are needed to address and mitigate these issues to ensure that navigation integrity is maintained and screw placement is accurate when using navigated robotic surgical guidance systems. The following research describes some potential hazards commonly encountered in robotic navigated screw placement, suggests techniques for overcoming these hazards, and provides examples of how these techniques have been incorporated into existing surgical robotic guidance systems. [ABSTRACT FROM AUTHOR]

Robotic systems in surgery have developed rapidly. Installations of the da Vinci Surgical System® (Intuitive Surgical, Sunnyvale, CA, USA), widely used in urological and gynecological procedures, have nearly doubled in the United States from 2010 to 2017. Robotics systems in spine surgery have been adopted more slowly; however, users are enthusiastic about their applications in this subspecialty. Spinal surgery often requires fine manipulation of vital structures that must be accessed via limited surgical corridors and can require repetitive tasks over lengthy periods of time — issues for which robotic assistance is well-positioned to complement human ability. To date, the United States Food and Drug Administration (FDA) has approved 7 robotic systems across 4 companies for use in spinal surgery. The available clinical data evaluating their efficacy have generally demonstrated these systems to be accurate and safe. A critical next step in the broader adoption of surgical robotics in spine surgery is the design and implementation of rigorous comparative studies to interrogate the utility of robotic assistance. Here we discuss current applications of robotics in spine surgery, review robotic systems FDA-approved for use in spine surgery, summarize randomized controlled trials involving robotics in spine surgery, and comment on prospects of robotic-assisted spine surgery. [ABSTRACT FROM AUTHOR]