Spinal Hardware Research Articles

A computer vision approach to identifying the manufacturer and model of anterior cervical spinal hardware.

Recent advances in computer vision have revolutionized many aspects of society but have yet to find significant penetrance in neurosurgery. One proposed use for this technology is to aid in the identification of implanted spinal hardware. In revision operations, knowing the manufacturer and model of previously implanted fusion systems upfront can facilitate a faster and safer procedure, but this information is frequently unavailable or incomplete. The authors present one approach for the automated, high-accuracy classification of anterior cervical hardware fusion systems using computer vision. Patient records were searched for those who underwent anterior-posterior (AP) cervical radiography following anterior cervical discectomy and fusion (ACDF) at the authors' institution over a 10-year period (2008-2018). These images were then cropped and windowed to include just the cervical plating system. Images were then labeled with the appropriate manufacturer and system according to the operative record. A computer vision classifier was then constructed using the bag-of-visual-words technique and KAZE feature detection. Accuracy and validity were tested using an 80%/20% training/testing pseudorandom split over 100 iterations. A total of 321 total images were isolated containing 9 different ACDF systems from 5 different companies. The correct system was identified as the top choice in 91.5% ± 3.8% of the cases and one of the top 2 or 3 choices in 97.1% ± 2.0% and 98.4 ± 13% of the cases, respectively. Performance persisted despite the inclusion of variable sizes of hardware (i.e., 1-level, 2-level, and 3-level plates). Stratification by the size of hardware did not improve performance. A computer vision algorithm was trained to classify at least 9 different types of anterior cervical fusion systems using relatively sparse data sets and was demonstrated to perform with high accuracy. This represents one of many potential clinical applications of machine learning and computer vision in neurosurgical practice.

Esophageal Perforation due to Anterior Cervical Spine Hardware Placement: Case Series.

Context. This case series discusses surgical management of esophageal perforations that occurred following cervical spine hardware placement. Purpose. (1) Determine presenting symptoms of esophageal perforation after anterior cervical spine hardware placement. (2) Discuss surgical management of these resulting esophageal perforation complications. Design/Setting. Case series of six patients at a tertiary-care, academic medical center. Patient Sample. Six patients with pharyngoesophageal perforations following anterior cervical spine surgery (ACSS). Outcome Measures. Date of ACSS, indication for ACSS, level of hardware, location of esophageal or pharyngeal injury, symptoms at presentation, surgical intervention, type of reconstruction flap, wound culture flora, and antibiotic choice. Methods. A retrospective review of patients with an esophageal or hypopharyngeal injury in the setting of prior ACSS managed by the otolaryngology service at a tertiary, academic center between January 2015 and January 2019. Results. Six patients who experienced pharyngoesophageal perforation following ACSS are included in this study. Range of presentation was two weeks to eight years following initial hardware placement. Five patients presented with an abscess and all had evidence of perforation on initial CT or esophagram. All patients underwent repair with a sternocleidomastoid flap with two patients eventually requiring an additional pectoralis myofascial flap for a persistent esophageal leak. Five patients eventually attained ability to tolerate oral nutrition. An algorithm detailing surgical reconstructive management is proposed. Conclusions. Esophageal perforations in the setting of prior ACSS are challenging clinical problems faced by otolaryngologists. Consideration should be given to early drainage of abscesses and spine surgery evaluation. Spinal hardware removal is recommended whenever possible. Utilization of a pedicled muscle flap reinforces primary closure and allows coverage of the vertebral bony defect. Nutrition, thyroid repletion, and culture-directed IV antibiotics are necessary to optimize esophageal perforation repair.

Update on Imaging of Spinal Fixation Hardware.

This article discusses instrumented spinal surgeries, the radiologic assessment of spinal fixation hardware, and the potential complications of spinal hardware. Radiography is the standard for the postoperative assessment of spinal hardware. Computed tomography and magnetic resonance imaging play a valuable role in the detection of hardware and postsurgical-related complications such as infection, pseudarthrosis, and malpositioned instrumentation. Familiarity with the normal imaging appearance of implanted spinal hardware along with the expected progression of normal postoperative osseous arthrodesis enables recognition of potential complications and helps facilitate appropriate clinical management.

The complications associated with guidewire use in spine surgeries involving pedicle screw placement: A comprehensive literature review

Guidewires (Kirschner or “K” wires) are often required during minimally invasive spine surgery to facilitate percutaneous pedicle screw placement. The use of guidewires involves a multi-step process that carries the risk of complications and their associated consequences. To date, the reporting of such information has been limited, and the literature has not been thoroughly evaluated. The objective of this study was to conduct a narrative review and assess the burden associated with guidewire use in spine surgeries. Databases searched included PubMed and Embase between the years of 1988 and 2017. In addition to databases, recent data from relevant trade journals were hand-searched. Inclusion criteria were broad to avoid potential exclusion of relevant publications. In total, 31 articles were included. This review found that the risk of complications associated with guidewire use in spine procedures ranged from 0.4% to 14.8%. Complication types included guidewire fracture, cerebrospinal fluid leakage, post-operative ileus, infection, and other spinal hardware failure (e.g., pedicle screw pull-out). Causes of complications typically included breakage and migration of the guidewire (metal fatigue), inexperience with guidewire use, or lack of tactile or visual feedback. Specific surgery types or patient populations may be more susceptible to guidewire-related complications (e.g., L5-S1 level operations). Complications associated with guidewire use may also lead to healthcare resource utilization, including additional operating time, radiation exposure, and re-operations. Solutions to help minimize the risk of such complications and associated consequences are required.

1983. Oral Therapy with Rifampin Associated with Minocycline or Moxifloxacin in Vertebral Osteomyelitis due to Gram-Positive Micro-organisms: A Retrospective Study of 64 Cases

BackgroundIDSA guidelines about vertebral osteomyelitis (VO) recommend parenteral antimicrobial therapy (PAT) as the standard treatment for Gram-positive pathogens (GPP). In this setting, a switch to oral antimicrobial therapy (OAT) with excellent bioavailability could be considered. However, among fluoroquinolones, moxifloxacine is not recommended in staphylococcal VO, and among tetracycline, only doxycycline should be considered with rifampin, for brucelar VO. The aim of our study was to review the efficacy and safety of OAT with rifampin associated with moxifloxacin (Rif-Mox) or minocycline (Rif-Mino) in the treatment of VO due to GPP.MethodsObservational, retrospective study in a Belgian teaching hospital, over 10 years. All charts with a diagnosis of VO were reviewed. Patients with VO who received definite OAT with Rif-Mox or Rif-Mino were included. An episode of VO caused by the same species within 24 months after the initial episode represented a relapse; other situations were considered as recurrences.ResultsOf 655 charts, 75 matched our inclusion criteria. Eleven were rejected: missing data six cases; death before the end of treatment five cases, including one death related to VO. Key data are shown in the figure. Fifty-five and 9 patients received Rif-Mox and Rif-Mino OAT, respectively. The median duration of PAT and OAT were 14 days and 64.5 days, respectively and the global treatment median duration was 89 days. The duration of PAT was essentially driven by the presence of an associated bacteremia or endocarditis, particularly in cases due to Staphylococci. Interestingly, OAT without initial PAT was performed in six cases without failure. The follow-up after end of therapy was ≥2 years. There was no recurrence or relapse in Rif-Mino group. In Rif-Mox group, there was one recurrence occuring 6 months after the end of therapy. Two others recurrences were observed >24 months after the end of therapy and were not notified. No treatment was stopped because of intolerance or significant adverse events.ConclusionOAT with Rif-Mox or Rif-Mino was safe, well tolerated and achieved a high level of cure in VO due to GPPs, including cases with spinal hardware infection. Disclosures All authors: No reported disclosures.

Instillation Negative Pressure Wound Therapy: An Effective Tool for Complex Spine Wounds.

Objective: Infection prevention in spinal surgeries involving implantation of hardware is of utmost priority. Furthermore, successful eradication of infection in hardware salvage is likewise critical in maintaining the long-term retention of the spinal hardware construct. Approach: We report a retrospective case series of three cases where the utilization of a VAC with instillation (VACi) in conjunction with surgical debridement aided in infection control and eradication for both preimplantation and hardware salvage spine patients. Results: Three patients were included. In case 1, VACi was utilized in conjunction with surgical debridement and IV antibiotics in the setting of acute preoperative infection to eradicate infection and enable necessary spinal hardware implementation. Cases 2 and 3 are representative of VACi for salvage of exposed spinal hardware in both the early and delayed infection presentation settings. In both cases, patients developed postoperative infections following spinal instrumentation VACi was utilized in conjunction with surgical debridement and IV antibiotics. Hardware removal was avoided in both cases. All three patients healed completely without residual evidence of infection. Innovation: VACi showed its effectiveness in timely infection eradication before spinal hardware instrumentation and with postoperative spine hardware salvage. Conclusion: This case series demonstrates that VACi can provide infection eradication both preoperatively in high-risk surgical sites, facilitating necessary hardware implementation and postoperatively in situations of hardware salvage.

A Retrospective Review of Spinal Radiofrequency Neurotomy Procedures in Patients with Metallic Posterior Spinal Instrumentation – Is it Safe?

Background: Recent studies have shown that medial branch radiofrequency neurotomy (RFN) procedures done at the level of a pedicle screw can increase pedicle screw temperature, and it has been speculated that pedicle screw heating may cause thermal injury. There has been a limited amount of investigation into the real-world safety profile of RFN procedures in patients with pedicle screws. Objectives: We aim to demonstrate that the occurrence of serious adverse events is rare for a medial branch RFN procedure completed at a level with metallic spinal hardware when performed according to the Spine Intervention Society practice standards. Study Design: This study involved retrospective chart reviews of every patient who received an RFN procedure for spinal facet joint pain during the 5-year time period from 2012-2016. Setting: The research took place within a single university-based interventional pain management center. Methods: The study sample included 507 patient charts. Data collection included patient demographics, RF denervation sites at a level with metallic hardware, and all serious RF-related complications that could be attributable to heated metallic hardware. The research team developed medical-chart abstraction criteria for each of the following categorized complications: a) superficial burns, b) deep burns, c) denervation of dorsal ramus, d) denervation of ventral ramus, and e) coagulation of a spinal vascular structure. Results: Of the 36 patients who met the inclusion criteria for this study, 43.6% were men and 56.4% were women. The mean age was 59.5 years old, with an age range of 25 to 87 years. There were a total of 56 ablations performed at a level with metallic spinal hardware, of which 11 were cervical, 44 were lumbar, and 1 was thoracic . There were zero documented complications found among our patient population in any of the 5 categories of serious complications. Limitations: As a retrospective chart review, this study was dependent on the availability and accuracy of medical records. Chart abstraction criteria for each outcome measure were developed by the research team without scientific testing. Conclusions: There have been no reported complications attributable to hardware temperature increases when performing medial branch RFNs at the level of a pedicle screw. For safety, it is important to use multiplanar fluoroscopic imaging techniques to ensure that the RFN cannula is not in contact with the pedicle screw. Key Words: Radiofrequency neurotomy, medial branch nerve ablation, safety, thermal injuries, metallic spinal hardware, pedicle screws, lateral mass screws, cervical facet joints, severe complications, adverse events

SMA THERAPIES I: P.171Transforaminal intrathecal delivery of nusinersen using cone-beam computed tomography in children with spinal muscular atrophy: results of technical success and safety

Nusinersen, the only treatment approved by the United States Food and Drug Administration for spinal muscular atrophy (SMA), is delivered intrathecally. Many children have a history of severe scoliosis and/or spinal fusion with instrumentation making access to the thecal space challenging using the standard interlaminar approach. The use of fluoroscopic guidance is complicated by the rotoscoliosis that is frequently found in children with SMA. Computed tomography (CT) facilitates cervical, caudal, and transforaminal approaches to the thecal space when the more traditional approach is not possible. This study, from one tertiary care pediatric hospital, describes the experience using cone-beam CT guidance with two-axis fluoroscopic navigational overlay to deliver intrathecal nusinersen in children with SMA who have spinal hardware precluding the standard posterior lumbar puncture technique. Results include a description of the technical success, complications and radiation dose over an 11-month period. We conducted a retrospective review of 36 consecutive nusinersen injections performed in 8 children with SMA who have extensive spinal hardware precluding the standard posterior lumbar puncture technique. An interventional radiologist, using a transforaminal thecal approach, employed cone-beam CT with navigational overlay to deliver nusinersen. We analyzed results including technical success, complications and total fluoroscopy time. Results: All transforaminal injections were technically successful. There were no major complications that occurred. We report 3 minor complication including; 2 complaints of transient radicular pain which resolved immediately after the spinal needle was removed and one post-procedural neuropathic headache that was attributed to positioning required for the procedure. This latter complication resulted in an overnight hospital stay and resolved after a short-term treatment with gabapentin. Radiation dosing was reported in 35 of 36 injections as data was not available for one injection. The average procedural fluoroscopy time and air kerma were 1.23 min and 73.54 mGy, respectively. Cone-beam CT guidance with two-axis navigational overlay is a safe, effective method for gaining transforaminal intrathecal access in children with spinal abnormalities and hardware precluding the use of standard techniques.

Native Valve Propionibacterium acnes Endocarditis From Self-injection of Vitamins

Native Valve Propionibacterium acnes Endocarditis From Self-injection of Vitamins

A comprehensive institutional overview of intrathecal nusinersen injections for spinal muscular atrophy.

Spinal muscular atrophy (SMA) is an autosomal-recessive neuromuscular disorder resulting in progressive muscle weakness. In December 2016, the U.S. Food and Drug Administration approved the first treatment for SMA, a drug named nusinersen (Spinraza) that is administered intrathecally. However many children with SMA have neuromuscular scoliosis or spinal instrumentation resulting in challenging intrathecal access. Therefore alternative routes must be considered in these complex patients. To investigate routes of drug access, we reviewed our institutional experience of administering intrathecal nusinersen in all children with spinal muscular atrophy regardless of spinal anatomy or instrumentation. We reviewed children with SMA who were referred for intrathecal nusinersen injections from March to December 2017 at our institution. In select children with spinal hardware, spinal imaging was requested to facilitate pre-procedure planning. Standard equipment for intrathecal injections was utilized. All children were followed up by their referring neurologist. A total of 104 intrathecal nusinersen injections were performed in 26 children with 100% technical success. Sixty procedures were performed without pre-procedural imaging and via standard interspinous technique. The remaining 44 procedures were performed in 11 complex (i.e. neuromuscular scoliosis or spinal instrumentation) patients requiring pre-procedural imaging for planning purposes. Nineteen of the 44 complex procedures were performed via standard interspinous technique from L2 to S1. Twenty-two of the 44 complex procedures were performed using a neural-foraminal approach from L3 to L5. Three of the 44 complex procedures were performed via cervical puncture technique. There were no immediate or long-term complications but there was one child with short-term complications of meningismus and back pain at the injection site. Although we achieved 100% technical success in intrathecal nusinersen administration, our practices evolved during the course of this study. As a result of our early experience we developed an algorithm to assist in promoting safe and effective nusinersen administration in children with spinal muscular atrophy regardless of SMA type, abnormal spinal anatomy and complex spinal instrumentation.

Adaptation of a clinical fixation device for biomechanical testing of the lumbar spine

In-vitro biomechanical testing is widely performed for characterizing the load-displacement characteristics of intact, injured, degenerated, and surgically repaired osteoligamentous spine specimens. Traditional specimen fixture devices offer an unspecified rigidity of fixation, while varying in the associated amounts and reversibility of damage to and “coverage” of a specimen – factors that can limit surgical access to structures of interest during testing as well as preclude the possibility of testing certain segments of a specimen. Therefore, the objective of this study was to develop a specimen fixture system for spine biomechanical testing that uses components of clinically available spinal fixation hardware and determine whether the new system provides sufficient rigidity for spine biomechanical testing. Custom testing blocks were mounted into a robotic testing system and the angular deflection of the upper fixture was measured indirectly using linear variable differential transformers. The fixture system had an overall stiffness 37.0, 16.7 and 13.3 times greater than a typical human functional spine unit for the flexion/extension, axial rotation and lateral bending directions respectively – sufficient rigidity for biomechanical testing. Fixture motion when mounted to a lumbar spine specimen revealed average motion of 0.6, 0.6, and 1.5° in each direction. This specimen fixture method causes only minimal damage to a specimen, permits testing of all levels of a specimen, and provides for surgical access during testing.

Transforaminal intrathecal delivery of nusinersen using cone-beam computed tomography for children with spinal muscular atrophy and extensive surgical instrumentation: early results of technical success and safety.

Nusinersen, the only treatment approved by the United States Food and Drug Administration for spinal muscular atrophy (SMA), is delivered intrathecally. Many children with SMA have extensive spinal instrumentation and deformities, often precluding the use of standard approaches for gaining intrathecal access. Furthermore the anatomical distortion that often occurs with rotoscoliosis can complicate the use of fluoroscopic guidance. Compared to fluoroscopy, CT affords superior guidance for complex needle placements. This opens up alternatives to the posterior (interlaminar) technique, including transforaminal and caudal approaches. This study describes the early results of technical success, complications and radiation dose of intrathecal delivery of nusinersen using cone-beam CT guidance with two-axis fluoroscopic navigational overlay. We conducted a retrospective review of 15 consecutive nusinersen injections performed in four children with SMA and extensive spinal hardware precluding standard posterior lumbar puncture techniques. These children were treated using transforaminal thecal access employing cone-beam CT with navigational overlay. We analyzed results including technical success, complications and total fluoroscopy time. All procedures were technically successful. No major complications and one minor complication were reported; the minor complication was a post-procedural neuropathic headache that was attributed to procedural positioning and was treated successfully with gabapentin. The average procedural fluoroscopy time and air kerma were 1.9min and 55.8mGy, respectively. Cone-beam CT guidance with two-axis navigational overlay is a safe, effective method for gaining transforaminal intrathecal access in children with spinal abnormalities and hardware precluding the use of standard techniques.

Traumatic cervical epidural hematoma due to fusion mass fracture following elective rod removal

Many studies have examined complications associated with spinal instrumentation, however, few have analyzed complications associated with removal. In this case report, we outline the course of a patient who presented with cervical epidural hematoma secondary to fusion mass fracture five years after removal of spinal hardware.

Hardware failure in patients with metastatic cancer to the spine

BackgroundThe spine is the most common site of skeletal metastases, affecting approximately 30% of individuals with cancer. The aim of surgical treatment for metastatic spine disease is generally palliative to address pain and/or neurologic compromise, significantly improving patients’ quality of life. Patients with metastatic spine disease, however, represent a vulnerable cohort and may have comorbidities or previous treatments that impair the structural integrity of spinal hardware. As such, identifying factors that may contribute to hardware failure is an essential component in treating individuals with metastatic spine disease. ObjectiveThe aim of this study was to identify pre-operative risk factors associated with hardware failure in patients undergoing surgical treatment for metastatic spine disease. MethodsA retrospective cohort study was conducted to include patients surgically treated for metastatic spine tumors between 2003 and 2013, at a single institution. A univariate analysis was initially performed to identify associated factors. Any associated factor with a p-value <0.20 was included in the multivariate analysis. Results3 patients (1.9%), of the 159 patients included in the study, had failure of the spine instrumentation. 1 patient had metastatic prostate cancer, and 2 had metastatic breast cancer. Patient demographics, co-morbidities, tumor location, and primary tumor etiology were not found to be statistically significant, with respect to hardware failure. Predictive factors included in the multivariate model were other bone metastasis, visceral metastasis, brain metastasis, Modified Rankin scale, previous systemic chemotherapy, previous radiation to the spine, and mean survival. Previous radiation to the spine was the only factor to be significantly associated (p=0.029), present in all three patients with hardware failure. Of note, there was a trend indicating that patients with longer life expectancies were more likely to experience hardware failure (mean survival of 16.7months in non-failure cohort vs. 33months in failure cohort), though this did not achieve statistical significance due to the limited sample size of patients with hardware failure. ConclusionHardware failure is a risk for all patients who undergo instrumentation following resection for metastatic spine tumors. This study identified that pre-operative radiation may increase the risk for hardware failure in this population.

Imaging the Spine with Dual-Energy CT

This review article aims to summarize the available literature regarding the utility of Dual-Energy CT (DECT) in spine imaging. DECT using virtual non-calcium images, virtual monoenergetic images, and material decomposition techniques have shown promise in bone marrow edema visualization associated with vertebral fractures, metallic artifact reduction related to spinal hardware, axial monosodium urate deposit detection, bone marrow composition evaluation, and bone marrow lesion identification. In our experience, DECT may also be an assuring technique in evaluation of disc degeneration, and disc herniation. DECT imaging of the spine has numerous clinical applications, potential advantages over single-energy CT and other imaging modalities, and future promising avenues.

Combinatory antibiotic therapy increases rate of bacterial kill but not final outcome in a novel mouse model of Staphylococcus aureus spinal implant infection

BackgroundManagement of spine implant infections (SII) are challenging. Explantation of infected spinal hardware can destabilize the spine, but retention can lead to cord compromise and biofilm formation, complicating management. While vancomycin monotherapy is commonly used, in vitro studies have shown reduced efficacy against biofilm compared to combination therapy with rifampin. Using an established in vivo mouse model of SII, we aim to evaluate whether combination therapy has increased efficacy compared to both vancomycin alone and infected controls.MethodsAn L-shaped, Kirschner-wire was transfixed into the L4 spinous process of 12-week-old C57BL/6 mice, and inoculated with bioluminescent Staphylococcus aureus. Mice were randomized into a vancomycin group, a combination group with vancomycin plus rifampin, or a control group receiving saline. Treatment began on post-operative day (POD) 7 and continued through POD 14. In vivo imaging was performed to monitor bioluminescence for 35 days. Colony-forming units (CFUs) were cultured on POD 35.ResultsBioluminescence peaked around POD 7 for all groups. The combination group had a 10-fold decrease in signal by POD 10. The vancomycin and control groups reached similar levels on POD 17 and 21, respectively. On POD 25 the combination group dropped below baseline, but rebounded to the same level as the other groups, demonstrating a biofilm-associated infection by POD 35. Quantification of CFUs on POD 35 confirmed an ongoing infection in all three groups.ConclusionsAlthough both therapies were initially effective, they were not able to eliminate implant biofilm bacteria, resulting in a rebound infection after antibiotic cessation. This model shows, for the first time, why histologic-based, static assessments of antimicrobials can be misleading, and the importance of longitudinal tracking of infection. Future studies can use this model to test combinations of antibiotic therapies to see if they are more effective in eliminating biofilm prior to human trials.

Osseodensification for enhancement of spinal surgical hardware fixation

Integration between implant and bone is an essential concept for osseous healing requiring hardware placement. A novel approach to hardware implantation, termed osseodensification, is described here as an effective alternative. 12 sheep averaging 65kg had fixation devices installed in their C2, C3, and C4 vertebral bodies; each device measured 4mm diameter×10mm length. The left-sided vertebral body devices were implanted using regular surgical drilling (R) while the right-sided devices were implanted using osseodensification drilling (OD). The C2 and C4 vertebra provided the t=0 in vivo time point, while the C3 vertebra provided the t=3 and t=6 week time points, in vivo. Structural competence of hardware was measured using biomechanical testing of pullout strength, while the quality and degree of new bone formation and remodeling was assessed via histomorphometry. Pullout strength demonstrated osseodensification drilling to provide superior anchoring when compared to the control group collapsed over time with statistical significance (p<0.01). On Wilcoxon rank signed test, C2 and C4 specimens demonstrated significance when comparing device pullout (p=0.031) for both, and C3 pullout tests at 3 and 6 weeks collapsed over time had significance as well (p=0.027). Percent bone-to-implant contact (%BIC) analysis as a function of drilling technique demonstrated an OD group with significantly higher values relative to the R group (p<0.01). Similarly, percent bone-area-fraction-occupancy (BAFO) analysis presented with significantly higher values for the OD group compared to the R group (p=0.024). As a function of time, between 0 and 3 weeks, a decrease in BAFO was observed, a trend that reversed between 3 and 6 weeks, resulting in a BAFO value roughly equivalent to the t=0 percentage, which was attributed to an initial loss of bone fraction due to remodeling, followed by regaining of bone fraction via production of woven bone. Histomorphological data demonstrated autologous bone chips in the OD group with greater frequency relative to the control, which acted as nucleating surfaces promoting new bone formation around the implants, providing superior stability and greater bone density. This alternative approach to a critical component of hardware implantation encourages assessment of current surgical approaches to hardware implantation.

A pilot cadaveric study of temperature and adjacent tissue changes after exposure of magnetic-controlled growing rods to MRI

To test for possible thermal injury and tissue damage caused by magnetic-controlled growing rods (MCGRs) during MRI scans. Three fresh frozen cadavers were utilized. Four MRI scans were performed: baseline, after spinal hardware implantation, and twice after MCGR implantation. Cross connectors were placed at the proximal end and at the distal end of the construct, making a complete circuit hinged at those two points. Three points were identified as potential sites for significant heating: adjacent to the proximal and distal cross connectors and adjacent to the actuators. Data collected included tissue temperatures at baseline (R1), after screw insertion (R2), and twice after rod insertions (R3 and R4). Tissue samples were taken and stained for signs of heat damage. There was a slight change in tissue temperature in the regions next to the implants between baseline and after each scan. Average temperatures (°C) increased by 0.94 (0.16-1.63) between R1 and R2, 1.6 (1.23-1.97) between R2 and R3, and 0.39 (0.03-0.83) between R3 and R4. Subsequent histological analysis revealed no signs of heat induced damage. Recurrent MRI scans of patients with MCGRs may be necessary over the course of treatment. When implanted into human cadaveric tissue, these rods appear to not be a risk to the patient with respect to heating or tissue damage. Further in vivo study is warranted. N/A.

Altered pharyngeal structure and dynamics among patients with cervical kyphosis.

Deformities of the anterior cervical spine are an established cause of dysphagia. Whereas osteophytes and spinal fusion hardware have been reported to alter bolus flow and contribute to swallowing dysfunction, the relationship between abnormal spine curvature and swallowing dysfunction is not established. The purpose of this investigation was to evaluate the association between cervical kyphosis and objective measures of swallowing dysfunction on videofluoroscopy. Case-control study of patients presenting to tertiary dysphagia center. All videofluoroscopic swallow studies (VFSS) performed at our institution, between August 1, 2014, and August 1, 2015, were retrospectively reviewed to identify patients with abnormal cervical kyphosis, according to Cobb and Jackson angle measurements. Patients with kyphosis were age- and gender-matched to persons without kyphosis. VFSS and demographic parameters were collected and compared between groups. Thirty-six patients with cervical kyphosis exceeding two standard deviations (SD) beyond established age-specific normal ranges were identified. The mean age of the entire cohort was 61.6 (SD ±19.1) years. Mean pharyngeal area was 3.34 cm2 greater in kyphosis patients compared to controls (95% confidence interval [CI]: 0.47-5.21 cm2 ; P = .0007). This was associated with increased hypopharyngeal transit time (0.57 seconds, 95% CI: 0.045-1.09 seconds, P = .034), and higher prevalence of penetration (P = .014). There was no significant difference in the pharyngeal constriction ratio (PCR), a surrogate measure of pharyngeal strength (P = .83). Patients with cervical spine kyphosis have a significantly dilated pharynx (P = .0007), elongated hypopharyngeal transit time (P = .034), and worsened penetration aspiration scores (P = .021). Absence of a difference in PCR suggests adequate compensation as a group. 3b. Laryngoscope, 127:1832-1837, 2017.

Detethering of the C2 Nerve Root and Avoidance of Transection and Injury During C1 Screw Placement: A Cadaveric Feasibility Study

Regional neurovascular structures must be avoided during invasive spine hardware placement. During C1 lateral mass screw placement, the C2 nerve root is put in harm's way. Therefore the current anatomic study was performed to identify techniques that might avoid such neural injury. On 10 cadaveric sides, dissection was carried down to the craniocervical junction. The C2 nerve root was identified, and its distal branches were traced out into the surrounding posterior cervical musculature. Once dissected, the nerve was displaced inferiorly away from the lateral mass of C1. On all sides, the C2 nerve root could be easily detethered from surrounding tissues. On all sides, this allowed lateral mass screw placement without compression of the nerve. On the basis of our cadaveric study, the C2 nerve root can be detethered enough at the level of the posterior lateral mass of C1 to avoid its injury during screw placement into this area.