Synthesis and evaluation of a novel vancomycin-infused, biomimetic bone graft using a rat model of spinal implant-associated infection.

Background: Postoperative infection is a complication of spinal fusion surgery resulting in increased patient morbidity. Strategies including intraoperative application of powdered vancomycin have been proposed to reduce the incidence of infection; however, such antimicrobial effects are short-lived. Methods: Instrumentation of the L4-L5 vertebrae was performed mimicking pedicle screw and rod fixation in 30 rats. Titanium instrumentation inoculated with either PBS or 1×105 CFU bioluminescent MRSA, along with biomimetic bone grafts infused with varying concentrations of vancomycin and 125 µg of rhBMP-2 (BioMim-rhBMP-2-VCM) were implanted prior to closure. Infection was quantified during the six-week postoperative period using bioluminescent imaging. Arthrodesis was evaluated using micro-CT. Results: Infected animals receiving a bone graft infused with low-dose (0.18 mg/g) or high-dose vancomycin (0.89 mg/g) both exhibited significantly lower bioluminescent signal over the six-week postoperative period than control animals inoculated with MRSA and implanted with bone grafts lacking vancomycin (p=.019 and p=.007, respectively). Both low and high-dose vancomycin-infused grafts also resulted in a statistically significant reduction in average bioluminescence when compared to control animals (p=.027 and p=.047, respectively), independent of time. MicroCT analysis of animals from each group revealed pseudoarthrosis only in the control group, suggesting a correlation between infection and pseudoarthrosis. MRSA-inoculated control animals also had significantly less bone volume formation on micro-CT than the PBS-inoculated control cohort (p<.001), the MRSA+low-dose vancomycin-infused bone graft cohort (p<.001), and the MRSA+high-dose vancomycin-infused bone graft cohort (p<.001). Conclusion: BioMim-rhBMP-2-VCM presents a novel tissue engineering approach to simultaneously promoting arthrodesis and antimicrobial prophylaxis in spinal fusion. Despite mixed evidence of potential osteotoxicity of vancomycin reported in literature, BioMim-rhBMP-2-VCM preserved arthrodesis and osteogenesis with increasing vancomycin loading doses due to the graft's osteoinductive composition.

Advancements in Robotic-Assisted Spine Surgery.

Applications and workflows around spinal robotics have evolved since these systems were first introduced in 2004. Initially approved for lumbar pedicle screw placement, the scope of robotics has expanded to instrumentation across different regions. Additionally, precise navigation can aid in tumor resection or spinal lesion ablation. Robot-assisted surgery can improve accuracy while decreasing radiation exposure, length of hospital stay, complication, and revision rates. Disadvantages include increased operative time, dependence on preoperative imaging among others. The future of robotic spine surgery includes automated surgery, telerobotic surgery, and the inclusion of machine learning or artificial intelligence in preoperative planning.

Tethered spinal cord tension assessed via ultrasound elastography in computational and intraoperative human studies.

BACKGROUND: Tension in the spinal cord is a trademark of tethered cord syndrome. Unfortunately, existing tests cannot quantify tension across the bulk of the cord, making the diagnostic evaluation of stretch ambiguous. A potential non-destructive metric for spinal cord tension is ultrasound-derived shear wave velocity (SWV). The velocity is sensitive to tissue elasticity and boundary conditions including strain. We use the term Ultrasound Tensography to describe the acoustic evaluation of tension with SWV. METHODS: Our solution Tethered cord Assessment with Ultrasound Tensography (TAUT) was utilized in three sub-studies: finite element simulations, a cadaveric benchtop validation, and a neurosurgical case series. The simulation computed SWV for given tensile forces. The cadaveric model with induced tension validated the SWV-tension relationship. Lastly, SWV was measured intraoperatively in patients diagnosed with tethered cords who underwent treatment (spinal column shortening). The surgery alleviates tension by decreasing the vertebral column length. RESULTS: Here we observe a strong linear relationship between tension and squared SWV across the preclinical sub-studies. Higher tension induces faster shear waves in the simulation (R2 = 0.984) and cadaveric (R2 = 0.951) models. The SWV decreases in all neurosurgical procedures (p < 0.001). Moreover, TAUT has a c-statistic of 0.962 (0.92-1.00), detecting all tethered cords. CONCLUSIONS: This study presents a physical, clinical metric of spinal cord tension. Strong agreement among computational, cadaveric, and clinical studies demonstrates the utility of ultrasound-induced SWV for quantitative intraoperative feedback. This technology is positioned to enhance tethered cord diagnosis, treatment, and postoperative monitoring as it differentiates stretched from healthy cords.

Tethered spinal cord syndrome occurs when surrounding tissue attaches to and causes stretching across the spinal cord. People with a tethered cord can experience weakness, pain, and loss of bladder control. Although increased tension in the spinal cord is known to cause these symptoms, evaluating the amount of stretching remains challenging. We investigated the ability of an ultrasound imaging approach to measure spinal cord tension. We studied our method in a computer simulation, a benchtop validation model, and in six people with tethered cords during surgery that they were undergoing to reduce tension. In each phase, the approach could detect differences between stretched spinal cords and spinal cords in a healthy state. Our method could potentially be used in the future to improve the care of people with a tethered cord.

Non-contrast ultrasound image analysis for spatial and temporal distribution of blood flow after spinal cord injury.

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.

Cervical and Lumbar Disk Replacement in Athletes: Is It Safe to Return to Play? A Systematic Review of the Scientific Literature and Lay Press.

BACKGROUND AND OBJECTIVES: Cervical/lumbar total disk replacements (TDRs) are often performed for degenerative conditions but rarely in athletes. Therefore, we sought to conduct a systematic review of athletes undergoing TDRs of both the scientific literature and lay press, with an emphasis on contact sport athletes. METHODS: In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, PubMed/Embase/Cochrane/Scopus/Web of Science databases were queried for all primary literature reporting TDRs in athletes, including both cervical/lumbar disk replacements (CDRs/LDRs). Sports were dichotomized into contact vs limited/noncontact. Because of the public nature of injuries in elite athletes, the lay press was also queried. RESULTS: A total of 488 scientific studies were screened, of which 10 met inclusion criteria. Cervical: seven studies reported CDRs in 53 athletes, of which 7 were professional, 22 semiprofessional, and 24 recreational. Of the seven professional athletes, there was one contact sport athlete (kickboxer). All 7/7 professional and 21/22 semiprofessional athletes successfully returned-to-play at 8-52 weeks without complication. Lumbar: Three studies discussed LDRs in 51 athletes, of which 17 were professional, 6 semiprofessional, and 28 recreational. Of the 17 professional athletes, eight played contact sports (2 boxing, 2 alpine skiing, 2 soccer, judo, rugby). All 17 professional and 6 semiprofessional athletes successfully returned to play at 9-21 weeks. Lay Press: five professional contact sport athletes underwent CDRs, and all returned to play: 3 hockey, 1 mixed-martial arts, and 1 Australian-rules football. CONCLUSION: The scientific literature and lay press revealed 14 professional contact sport athletes who underwent TDR-6 CDRs and 8 LDRs-all with successful return to play. From the little data that exist, it seems that TDR may be safe in elite athletes; however, the small number of patients highlights the major paucity of data on the safety of TDR in elite contact sport athletes.

Early versus late surgical decompression for patients with acute traumatic central cord syndrome: a systematic review and meta-analysis.

BACKGROUND CONTEXT: The optimal decompression time for patients presenting with acute traumatic central cord syndrome (ATCCS) has been debated, and a high level of evidence is lacking. PURPOSE: To compare early (<24 hours) versus late (≥24 hours) surgical decompression for ATCCS. STUDY DESIGN: Systematic review and meta-analysis. METHODS: Medline, PubMed, Embase, and CENTRAL were searched from inception to March 15th, 2023. The primary outcome was American Spinal Injury Association (ASIA) motor score. Secondary outcomes were venous thromboembolism (VTE), total complications, overall mortality, hospital length of stay (LOS), and ICU LOS. The GRADE approach determined certainty in evidence. RESULTS: The nine studies included reported on 5,619 patients, of whom 2,099 (37.35%) underwent early decompression and 3520 (62.65%) underwent late decompression. The mean age (53.3 vs 56.2 years, p=.505) and admission ASIA motor score (mean difference [MD]=-0.31 [-3.61, 2.98], p=.85) were similar between the early and late decompression groups. At 6-month follow-up, the two groups were similar in ASIA motor score (MD= -3.30 [-8.24, 1.65], p=.19). However, at 1-year follow-up, the early decompression group had a higher ASIA motor score than the late decompression group in total (MD=4.89 [2.89, 6.88], p<.001, evidence: moderate), upper extremities (MD=2.59 [0.82, 4.36], p=.004) and lower extremities (MD=1.08 [0.34, 1.83], p=.004). Early decompression was also associated with lower VTE (odds ratio [OR]=0.41 [0.26, 0.65], p=.001, evidence: moderate), total complications (OR=0.53 [0.42, 0.67], p<.001, evidence: moderate), and hospital LOS (MD=-2.94 days [-3.83, -2.04], p<.001, evidence: moderate). Finally, ICU LOS (MD=-0.69 days [-1.65, 0.28], p=.16, evidence: very low) and overall mortality (OR=1.35 [0.93, 1.94], p=.11, evidence: moderate) were similar between the two groups. CONCLUSIONS: The meta-analysis of these studies demonstrated that early decompression was beneficial in terms of ASIA motor score, VTE, complications, and hospital LOS. Furthermore, early decompression did not increase mortality odds. Although treatment decision-making has been individualized, early decompression should be considered for patients presenting with ATCCS, provided that the surgeon deems it appropriate.

SPECT/CT and PET/CT for the Evaluation of Persistent or Recurrent Pain After Spine Surgery: A Systematic Review and Case Series.

OBJECTIVE: The differential diagnosis for postoperative back pain is broad, and conventional imaging modalities are not always conclusive. Therefore, we performed a systematic review of the literature and present case studies describing the use of single-photon emission CT (SPECT)/CT or positron emission tomography (PET)/CT in the diagnosis of back pain following spine surgery. METHODS: A systematic review was conducted according to PRISMA guidelines across 5 databases. Relevant keywords included PET/CT, bone SPECT/CT, and pseudarthrosis. The studies were assessed for diagnostic accuracy of the imaging technologies. RESULTS: A total of 2,444 studies were screened, 91 were selected for full-text review, and 21 were ultimately included. Six retrospective studies investigated the use of SPECT/CT with a total sample size of 309 patients. Two of these studies used SPECT/CT to predict screw loosening in over 50% of patients. Eight studies examined the use of 18-fluoride sodium fluoride (18F-NaF) PET/CT. Among these studies, measures of diagnostic accuracy varied but overall demonstrated the ability of 18F-NaF PET/CT to detect screw loosening and pseudarthrosis. Seven studies examined 18F-fluorodeoxyglucose (FDG) PET/CT and supported its utility in the diagnosis of postoperative infections in the spine. CONCLUSIONS: PET/CT and SPECT/CT are useful in the evaluation of postoperative pain of the spine, especially in patients for whom conventional imaging modalities yield inconclusive results. More diagnostic accuracy studies with strong reference standards are needed to compare hybrid imaging to conventional imaging.

Exoscope Use in Spine Surgery: A Systematic Review of Applications, Benefits, and Limitations.

BACKGROUND: Exoscopes were recently developed as an alternative to the operative microscope (OM) and endoscope for intraoperative visualization during neurosurgery. Prior reviews studying mixed cranial and spinal surgical cohorts reported advantages with exoscope use, including improved ergonomics and teaching. In recent years, there has been an increase in exoscope research, with no updated systematic review focused exclusively on the benefits and limitations of exoscope use in spine surgery. Thus, we sought to systematically synthesize the literature related to exoscope-assisted spine surgery. METHODS: A literature search was conducted using the PubMed, Embase, Scopus, Cochrane, and Web of Science databases to identify relevant studies reported between 2010 and September 2023. Data, such as the exoscope model used, procedure types performed, and user observations, were then collected. RESULTS: A total of 31 studies met our inclusion criteria, including 481 patients with spine pathologies who underwent a surgical procedure using 1 of 9 exoscope models. The lumbar region was the most frequently operated area (n = 234; 48.6%), and discectomies comprised the most overall procedures (n = 273; 56.8%). All patients benefited clinically. The reported advantages of exoscopes compared with OMs or endoscopes were improved focal distance, surgeon posture, trainee education, compactness, and assistant participation. Other aspects such as stereopsis, illumination, and cost had various observations. CONCLUSIONS: Exoscopes have advantages compared with OMs or endoscopes during spine surgery. The user learning curve is minimal, and no negative patient outcomes have been reported. However, some aspects of exoscope use necessitate longer term prospective research before exoscopes can be considered a standard tool in the armamentarium of intraoperative visualization strategies.

A future blood test for acute traumatic spinal cord injury.

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.

Transpedicular Onyx embolization of a thoracic hemangioma with robotic assistance: illustrative case.

BACKGROUND: Hemangiomas are common benign vascular lesions that rarely present with pain and neurological deficits. Symptomatic lesions are often treated with endovascular embolization. However, transarterial embolization can be technically challenging depending on the size and caliber of the vessels. Moreover, embolization can result in osteonecrosis and vertebral collapse. OBSERVATIONS: Here the authors report the first case of a T10 vertebral hemangioma treated with transpedicular Onyx embolization aided by a robotic platform that guided pedicle cannulation and Craig needle placement. An intravenous catheter was attached to the needle and dimethylsulfoxide was infused, followed by Onyx under real-time fluoroscopy. Repeat angiography demonstrated significantly reduced contrast opacification of the vertebral body without compromise of the segmental artery. A T9-11 pedicle screw fixation was performed to optimize long-term stability. The patient's symptoms improved and was stable at the 6-month follow-up. LESSONS: Transpedicular embolization of vertebral hemangiomas can be performed successfully under robotic navigation guidance, avoiding complications seen with the intra-arterial approach and allowing for simultaneous pedicle screw fixation to prevent collapse and delayed kyphotic deformity. During the same procedure, a biopsy specimen can be collected for pathology. This technique can help to alleviate patient symptoms while avoiding complications associated with transarterial embolization or open resection.

Abra-ka-diskus: Vanishing Calcified Herniated Thoracic Disk.

Herniated thoracic disk has an incidence of 1/1 million. Treatment options for a calcified herniated disk include conservative management or diskectomy with or without fusion. We describe a patient who presented a year ago with a 5-month history of back pain, thoracic radiculopathy, and normal physical examination. Imaging revealed a giant calcified herniated thoracic disk at T10-T11. She underwent epidural steroid injections and chiropractic manipulation. Imaging obtained at 1-year follow-up showed near-complete resorption of the calcified thoracic disk.

Learning Curves for Robot-Assisted Pedicle Screw Placement: Analysis of Operative Time for 234 Cases.

BACKGROUND AND OBJECTIVES: Robot-assisted pedicle screw placement is associated with greater accuracy, reduced radiation, less blood loss, shorter hospital stays, and fewer complications than freehand screw placement. However, it can be associated with longer operative times and an extended training period. We report the initial experience of a surgeon using a robot system at an academic medical center. METHODS: We retrospectively reviewed all patients undergoing robot-assisted pedicle screw placement at a single tertiary care institution by 1 surgeon from 10/2017 to 05/2022. Linear regression, analysis of variance, and cumulative sum analysis were used to evaluate operative time learning curves. Operative time subanalyses for surgery indication, number of levels, and experience level were performed. RESULTS: In total, 234 cases were analyzed. A significant 0.19-minute decrease in operative time per case was observed (r = 0.14, P = .03). After 234 operations, this translates to a reduction in 44.5 minutes from the first to last case. A linear relationship was observed between case number and operative time in patients with spondylolisthesis (-0.63 minutes/case, r = 0.41, P < .001), 2-level involvement (-0.35 minutes/case, r = 0.19, P = .05), and 4-or-more-level involvement (-1.29 minutes/case, r = 0.24, P = .05). This resulted in reductions in operative time ranging from 39 minutes to 1.5 hours. Continued reductions in operative time were observed across the learning, experienced, and expert phases, which had mean operative times of 214, 197, and 146 minutes, respectively ( P < .001). General proficiency in robot-assisted surgery was observed after the 20th case. However, 67 cases were required to reach mastery, defined as the inflection point of the cumulative sum curve. CONCLUSION: This study documents the long-term learning curve of a fellowship-trained spine neurosurgeon. Operative time significantly decreased with more experience. Although gaining comfort with robotic systems may be challenging or require additional training, it can benefit surgeons and patients alike with continued reductions in operative time.

Robot-assisted screw fixation in a cadaver utilizing magnetic resonance imaging-based synthetic computed tomography: toward radiation-free spine surgery. Illustrative case.

BACKGROUND: Synthetic computed tomography (sCT) can be created from magnetic resonance imaging (MRI) utilizing newer software. sCT is yet to be explored as a possible alternative to routine CT (rCT). In this study, rCT scans and MRI-derived sCT scans were obtained on a cadaver. Morphometric analysis was performed comparing the 2 scans. The ExcelsiusGPS robot was used to place lumbosacral screws with both rCT and sCT images. OBSERVATIONS: In total, 14 screws were placed. All screws were grade A on the Gertzbein-Robbins scale. The mean surface distance difference between rCT and sCT on a reconstructed software model was -0.02 ± 0.05 mm, the mean absolute surface distance was 0.24 ± 0.05 mm, and the mean absolute error of radiodensity was 92.88 ± 10.53 HU. The overall mean tip distance for the sCT versus rCT was 1.74 ± 1.1 versus 2.36 ± 1.6 mm (p = 0.24); mean tail distance for the sCT versus rCT was 1.93 ± 0.88 versus 2.81 ± 1.03 mm (p = 0.07); and mean angular deviation for the sCT versus rCT was 3.2° ± 2.05° versus 4.04°± 2.71° (p = 0.53). LESSONS: MRI-based sCT yielded results comparable to those of rCT in both morphometric analysis and robot-assisted lumbosacral screw placement in a cadaver study.

Use of the Globus ExcelsiusGPS System for Robotic Stereoelectroencephalography: An Initial Experience.

BACKGROUND: Stereoelectroencephalography (SEEG) is a critical tool used in the identification of epileptogenic zones. Although stereotactic frame-based SEEG procedures have been performed traditionally, newer robotic-assisted SEEG procedures have become increasingly common. In this study, we evaluate the accuracy, efficacy of the ExcelsiusGPS robot (Globus Medica, Audubon, PA) in SEEG procedures. METHODS: Five consecutive adult patients with drug resistant epilepsy were identified as SEEG candidates via a multidisciplinary epilepsy surgery committee. Preoperative scans were merged onto the robot to plan electrode placement. With the use of a camera system, dynamic reference base, and surveillance markers, the robotic arm was used to establish the trajectory of the electrodes. Postoperative computed tomography (CT) scans were merged onto the preoperatively planned trajectory and the radial, depth, and entry errors were calculated. Fiducial registration error was calculated for 4 cases to determine error between the patient and intraoperative CT merge. RESULTS: A total of 59 electrodes were placed. The mean age at surgery was 41.6 ± 15.1 years. Mean operating room time, anesthesia time, and surgical time was 301.6 ± 44.4 min, 261.6 ± 50.2 min, and 155.8 ± 48.8 min, respectively. The overall mean depth, radial, and entry errors were 2.5 ± 1.9 mm, 1.9 ± 1.5 mm, and 1.6 ± 1.2 mm. Mean fiducial registration error retrospectively calculated for 4 of 5 cases was 0.13 ± 0.04 mm. There were no perioperative complications. CONCLUSIONS: The initial performance of the ExcelsiusGPS robotic system yielded comparable results to other systems currently in use for adult SEEG procedures.

Disruption of the Blood-Spinal Cord Barrier using Low-Intensity Focused Ultrasound in a Rat Model.

Low-intensity focused ultrasound (LIFU) uses ultrasonic pulsations at lower intensities than ultrasound and is being tested as a reversible and precise neuromodulatory technology. Although LIFU-mediated blood-brain barrier (BBB) opening has been explored in detail, no standardized technique for blood-spinal cord barrier (BSCB) opening has been established to date. Therefore, this protocol presents a method for successful BSCB disruption using LIFU sonication in a rat model, including descriptions of animal preparation, microbubble administration, target selection and localization, as well as BSCB disruption visualization and confirmation. The approach reported here is particularly useful for researchers who need a fast and cost-effective method to test and confirm target localization and precise BSCB disruption in a small animal model with a focused ultrasound transducer, evaluate the BSCB efficacy of sonication parameters, or explore applications for LIFU at the spinal cord, such as drug delivery, immunomodulation, and neuromodulation. Optimizing this protocol for individual use is recommended, especially for advancing future preclinical, clinical, and translational work.

Advancements in the treatment of traumatic spinal cord injury during military conflicts.

Significant advancements in the treatment of spinal cord injury (SCI) were developed in the setting of military conflicts, partly due to the large numbers of injuries sustained by service members. No effective SCI treatment options existed into the early 20th century, and soldiers who sustained these injuries were usually considered untreatable. Extensive progress was made in SCI treatment during and after World War II, as physical therapy was increasingly encouraged for patients with SCI, multidisciplinary teams oversaw care, pathophysiology was better understood, and strategies were devised to prevent wound infection and pressure sores. Recent conflicts in Iraq and Afghanistan have caused a substantial rise in the proportion of SCIs among causes of casualties and wounds, largely due to new forms of war and weapons, such as improvised explosive devices. Modern military SCIs resulting from blast mechanisms are substantively different from traumatic SCIs sustained by civilians. The treatment paradigms developed over the past 100 years have increased survival rates and outcomes of soldiers with SCI. In this paper, the authors review the role of military conflicts in the development of therapeutic interventions for SCI and discuss how these interventions have improved outcomes for soldiers and civilians alike.

Craniocervical instability in patients with Ehlers-Danlos syndrome: controversies in diagnosis and management.

Ehlers-Danlos syndrome (EDS) is a rare hereditary condition that can result in ligamentous laxity and hypermobility of the cervical spine. A subset of patients can develop clinical instability of the craniocervical junction associated with pain and neurological dysfunction, potentially warranting treatment with occipitocervical fixation (OCF). Surgical decision-making in patients with EDS can be complicated by difficulty distinguishing from hypermobility inherent in the disease and true pathological instability necessitating intervention. Here we comprehensively review the available medical literature to critically appraise the evidence behind various proposed definitions of instability in the EDS population, and summarize the available outcomes data after OCF. Several radiographic parameters have been used, including the clivo-axial angle, basion-axial interval, and pB-C2 measurement. Despite increasing recognition of EDS by spine surgeons, there remains a paucity of data supporting proposed radiographic parameters for spinal instability among EDS patients. Furthermore, there is a lack of high-quality evidence concerning the efficacy of surgical treatments for chronic debilitating pain prevalent in this population. More standardized clinical measures and rigorous study methodologies are needed to elucidate the role of surgical intervention in this complex patient population.

Robot-assisted atlantoaxial fixation: illustrative cases.

BACKGROUND: Placing screws in the high cervical spine can be challenging because of the vital anatomical structures located in that region. Precision and accuracy with screw placement is needed. The use of robotics in the cervical spine has been described before; however, here the authors describe the use of a new robotic setup. OBSERVATIONS: The authors describe 2 cases of robot-assisted placement of C2 pars screws and C1-2 transarticular screws. The operative plans for each patient were as follows: placement of C2 pars screws with C2-4 fusion for hangman's fracture and placement of C1-2 transarticular screws for degenerative disease. Intraoperative computed tomography (CT) was used to plan and navigate the screws. Postoperative CT showed excellent placement of hardware. Both patients presented for initial postoperative clinic visits with no recurrence of prior symptoms. LESSONS: Intraoperative robotic assistance with instrumentation of the high cervical spine, particularly C2 pars and C1-2 transarticular screws, may ensure proper screw placement and help avoid injury.