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Navigated pedicle screw placement can be particularly challenging for cervical and upper thoracic levels in obese patients. This technical challenge can be compounded by smaller-diameter tools, which can be flexible and therefore confound navigation. It is imperative to avoid excessive manipulation of surrounding tissues to maintain navigation accuracy in the mobile cervical spine. 1 Robotic-assisted spinal approaches use firm guides to aid drilling and screw placement but are hindered by high costs with equipment acquisition. 2 , 3 Here, we propose a technical nuance that combines robotic surgical principles with tools that are more readily available in many surgical departments (Video 1). We present the case of a 64-year-old woman with a chief complaint of neck pain, irradiating to the left worse than right arm and prior history of C5-7 anterior cervical diskectomy and fusion. Imaging showed multilevel degenerative disease and a solid prior C5-7 anterior cervical diskectomy and fusion with grade I anterolisthesis at C7-T1 due to severe facet degeneration with severe left-sided foraminal stenosis. Given failure of conservative management, the patient was brought to the operating room for left C7-T1 foraminotomy and C7-T1 posterior instrumented fusion. Here, we show the use of a tubular retractor fixed to the surgical bed for solid and reproducible trajectory for all tools to minimize the risk of surrounding tissue manipulation and its effect on navigation accuracy., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Axial neck pain is often associated with cervical instability, and surgical options are often reserved for patients with either neurological compromise or deformity of the spine. However, cervical facet arthropathy is often implicated with instability and the location of painful generators is often difficult to ascertain. Single-photon emission computed tomography (SPECT-CT) presents an adjunct to conventional imaging in the workup of patients with suspected facetogenic pain. We aimed to report our experience with patients undergoing anterior cervical discectomy and fusion (ACDF) guided by SPECT-CT for axial cervical pain., Methods: We retrospectively identified all cases undergoing ACDF that presented with axial neck pain where correlating SPECT-CT high metabolism areas were identified. Patients were treated at a tertiary care institution between January 2018 and January 2021. Patients with positive radiotracer uptake pre-operatively were compared with patients undergoing ACDF without uptake on SPECT-CT. The pre- and post-operative patients who reported neck pain at one year were compared., Results: Thirty-five patients were included in this retrospective cohort. The median pre- and post-intervention (at one-year follow-up) visual analog score (VAS) of patients undergoing ACDF without uptake on SPECT-CT was 7 and 3 (p<0.01), while the pre- and post-VAS for patients undergoing surgery with positive uptake on SPECT-CT was 8.5 and 0 (p<0.01). Improvement was significantly larger for patients undergoing SPECT-CT-guided ACDF (p=0.02). At one year after surgery, none of the assessed patients required additional surgical intervention., Conclusion: This case series represents the experience of our group to date with patients undergoing SPECT-CT-guided ACDF with results suggesting potential benefit in guiding fusion., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, Garcia et al.)

Introduction: Cervical facet arthritis is a significant source of neck pain and impaired function that is amenable to treatment with medial branch radiofrequency neurotomy (RFN). Identifying appropriate patients for this treatment requires integration of information from the history, physical exam and diagnostic imaging, but the current diagnostic standard for facet-mediated pain is positive comparative medial branch blockade (MBB). SPECT-CT has recently been evaluated as a potential predictor of positive medial branch blocks with mixed results. The purpose of this retrospective analysis was to determine if a relationship exists between increased uptake on SPECT-CT of a given cervical facet joint and a positive MBB., Methods: A retrospective review was performed to identify all patients undergoing cervical MBB within 12 months after having a cervical SPECT-CT. Each procedure was categorized as either Concordant (all facet joints demonstrating increased 99m Tc uptake on SPECT-CT were blocked) or Discordant (at least one facet joint demonstrating increased 99m Tc uptake on SPECT-CT was not blocked or block was performed in a patient that had no increased uptake on SPECT-CT). Statistical analysis was performed to determine if concordance between facet joints demonstrating increased uptake on SPECT-CT and those undergoing MBB was associated with a positive block using cutoffs of 50% and 80% pain relief., Results: A total of 43 procedures were analyzed (25% Concordant, 75% Discordant) and both groups demonstrated improvement in pain Numeric Rating Scale (NRS) scores. No significant association between concordance and positive MBB was identified at thresholds of 50% (p = .481) and 80% (p = 1.000) pain relief., Conclusion: SPECT-CT findings do not accurately predict positive cervical MBB but may provide valuable information that can be considered with other factors when deciding which joints to treat., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Introduction: Lumbar facet arthritis is a significant source of back pain and impaired function that is amenable to treatment with medial branch radiofrequency neurotomy (RFN). Identifying appropriate patients for this treatment requires integration of information from the history, physical exam, and diagnostic imaging, but the current diagnostic standard for facet-mediated pain is positive comparative medial branch blocks (MBBs). Lumbar SPECT-CT has recently been evaluated as a potential predictor of positive MBBs with mixed results. The purpose of this retrospective analysis was to determine if the level of concordance between SPECT-CT uptake and facet joints targeted with MBB was associated with a positive block., Methods: A retrospective review was performed to identify all patients undergoing lumbar MBB within 12 months after having a lumbar SPECT-CT. Each procedure was classified into one of four categories based on the level of concordance between facet joints demonstrating increased 99m Tc uptake on SPECT-CT and those being blocked: 1) Complete Concordance (all joints demonstrating increased uptake were blocked and no additional joints blocked); 2) Partial Concordance (all joints demonstrating increased uptake were blocked, with at least one joint not demonstrating increased uptake blocked); 3) Partial Discordance (at least one but not all joints demonstrating increased uptake were blocked); 4) Complete Discordance (all blocks performed at joints not demonstrating increased uptake). Statistical analysis was performed to determine if the level of concordance between increased uptake on SPECT-CT and joints undergoing MBB was associated with a positive block using cutoffs of 50 % and 80 % pain relief., Results: A total of 180 procedures were analyzed (23 % Complete Concordance, 22 % Partial Concordance, 31 % Partial Discordance, 24 % Complete Discordance) and all groups demonstrated improvement in pain Numeric Rating Scale (NRS) scores. There was no significant association between level of concordance and having a positive block using thresholds of 50 % pain relief, χ 2 (3, N  = 180) = 4.880, p = .181; or 80 % pain relief, χ 2 (3, N  = 180) = 1.272, p = .736., Conclusion: SPECT-CT findings do not accurately predict positive lumbar MBB but may provide valuable information that can be considered with other factors when deciding which joints to treat., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Background and Objectives: Degenerative spine disease is a leading cause of disability, with increasing prevalence in the older patients. While age has been identified as an independent predictor of outcomes, its predictive value is limited for similar older patients. Here, we aimed to determine the most predictive frailty score of adverse events in patients aged 80 and older undergoing instrumented lumbar fusion., Methods: We proceeded with a multisite (3 tertiary academic centers) retrospective review including patients undergoing instrumented fusion aged 80 and older from January 2010 to present. A composite end point encompassing 30-day return to operating room, readmission, and mortality was created. We estimated the area under the receiver operating characteristic curve for frailty scores (Modified Frailty Index-5 [MFI-5], Modified Frailty Index-11 [MFI-11], and Charlson Comorbidity Index [CCI]) in relation to that composite score. In addition, we estimated the association between each score and the composite end point by means of logistic regression., Results: A total of 153 patients with an average age of 85 years at the time of surgery were included. We observed a 30-day readmission rate of 11.1%, reoperation of 3.9%, and mortality of 0.6%. The overall rate of the composite end point at 30 days was 25 (15.1%). The AUC for MFI-5 was 0.597 (0.501-0.693), for MFI-11 was 0.620 (0.518-0.723), and for CCI was 0.564 (0.453-0.675). The association between the scores and composite end point did not reach statistical significance for MFI-5 (odds ratio [OR] = 1.45 [0.98-2.15], P = .061) and CCI (OR = 1.13 [0.97-1.31], P = .113) but was statistically significant for MFI-11 (OR = 1.46 [1.07-2.00], P = .018)., Conclusion: This is the largest study comparing frailty index scores in octogenarians undergoing instrumented lumbar fusion. Our findings suggest that while MFI-11 score correlated with adverse events, the predictive ability of existing scores remains limited, highlighting the need for better approaches to identify select patients at age extremes., (Copyright © Congress of Neurological Surgeons 2024. All rights reserved.)

Background: Graduate surgical education is highly variable across regions and institutions regarding case volume and degree of trainee participation in each case. Dedicated educational curriculum using cadaveric tissue has been shown to enhance graduate surgical training, however with associated financial and utility burden to the institution., Objective: To investigate the utility of educational and cost applications of a novel method of combining mixed organic hydrogel polymers and 3-dimensional printed anatomic structures to create a complete "start-to-finish" simulation for resident education in spinal anatomy, instrumentation, and surgical techniques., Methods: This qualitative pilot study investigated 14 international participants on achievement of objective and personal learning goals in a standardized curriculum using biomimetic simulation compared with cadaveric tissue. A questionnaire was developed to examine trainee evaluation of individual anatomic components of the biomimetic simulators compared with previous experience with cadaveric tissue., Results: A total of 210 responses were acquired from 14 participants. Six participants originated from US residency education programs and 8 from transcontinental residency programs. Survey results for the simulation session revealed high user satisfaction. Score averages for each portion of the simulation session indicated learner validation of anatomic features for the simulation compared with previous cadaveric experience. Cost analysis resulted in an estimated savings of $10 833.00 for this single simulation session compared with previous cadaveric tissue sessions., Conclusion: The results of this study indicate a strong potential of establishing biomimetic simulation as a cost-effective and high-quality alternative to cadaveric tissue for the instruction of fundamental spine surgical techniques., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Objective: To explore the worldwide impact of a virtual neurosurgery-neuroscience lecture series on optimizing neurosurgical education with tele-teaching., Methods: A retrospective analysis was performed from our Zoom database to collect data from October 15, 2020, to December 14, 2020, and from September 27, 2021, to December 13, 2021. A comparative analysis of participants in the 2 different time frames was performed to investigate the impact of tele-teaching on neurosurgical education worldwide. To evaluate participant satisfaction, the yearly continuing medical education reports of 2020-2021 were analyzed. Data related to the distribution of lectures by subspecialties were also described., Results: Among the 11 lectures of the first period, 257 participants from 17 countries in 4 different continents were recorded, with a mean of 64 (standard deviation = 9.30) participants for each meeting; 342 attendees participated from 19 countries in 5 continents over the 11 lectures of the second part, with an average of 82.8 (standard deviation = 14.04) attendees; a statistically significant increase in participation between the 2 periods was identified (P < 0.001) A total of 19 (2020) and 21 (2021) participants submitted the continuing medical education yearly survey. More than 86.4% of overall responses considered the lectures "excellent." The main topics reported during lectures in 2020-2021 were related to brain tumors (33.7%) and education (22.1%)., Conclusions: The COVID-19 pandemic has increased the need to introduce new educational approaches for teaching novel ways to optimize patient care. Our multidisciplinary Web-based virtual lecture series could represent an innovative tele-teaching platform in neurosurgical training., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: The ability to accurately predict pain generators for chronic neck and back pain remains elusive., Objective: We evaluated whether injections targeted at foci with uptake on single-photon emission computerized tomography-computed tomography (SPECT-CT) were associated with improved outcomes in patients with chronic neck and back pain., Methods: A retrospective review was completed on patients undergoing SPECT-CT for chronic neck and back pain between 2016 and 2020 at a tertiary academic center. Patients' records were reviewed for demographic, clinical, imaging, and outcomes data. Only those patients who had facet injections after SPECT-CT were included in this evaluation. Patients undergoing injections targeted at foci of abnormal radiotracer uptake were compared with patients without uptake concerning immediate positive response, visual analog scale, and the need for additional injection or surgery at the target level., Results: A total of 2849 patients were evaluated with a SPECT-CT for chronic neck and back pain. Of those, 340 (11.9%) patients received facet joint injections after SPECT-CT. A propensity score regression analysis adjusted for age, gender, body mass index, hypertension, multiple target injections, and injection location showed uptake targeted injections not being associated with an improved immediate positive response (odds ratio: 0.64; 95% confidence interval: 0.34-1.21; P = 0.172). In patients with a failed facet injection preceding SPECT-CT, adding SPECT-CT to guide facet injections was associated with a decrease in visual analog scale pain scores 2 weeks after injection (P = 0.018), particularly when changes were made to the facets being targeted (P = 0.010)., Conclusion: This study suggests that there is benefit with SPECT-CT specially to guide facet injections after failed prior facet injections., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Minimally invasive transforaminal interbody fusion has become an increasingly common approach in adult degenerative spine disease but is associated with a steep learning curve. We sought to evaluate the impact of the learning experience on mean procedure time and mean cost associated with each procedure., Methods: We studied the first 100 consecutive minimally invasive transforaminal interbody fusion procedures of a single surgeon. We performed multivariable linear regression models, modeling operating time, and costs in function of the procedure order adjusted for patients' age, sex, and number of surgical levels. The number of procedures necessary to attain proficiency was determined through a k-means cluster analysis. Finally, the total excess operative time and total excess cost until obtaining proficiency was evaluated., Results: Procedure order was found to impact procedure time and mean costs, with each successive case being associated with progressively less procedure time and cost. On average, each successive case was associated with a reduction in procedure time of 0.97 minutes (95% confidence interval 0.54-1.40; P < 0.001) and an average adjusted reduction in overall costs of $82.75 (95% confidence interval $35.93-129.57; P < 0.001). An estimated 58 procedures were needed to attain proficiency, translating into an excess procedure time of 2604.2 minutes (average of 45 minutes per case), overall costs associated with the learning experience of $226,563.8 (average of $3974.80 per case), and excess surgical cost of $125,836.6 (average of $2207.66 per case)., Conclusions: Successive cases were associated with progressively less procedure time and mean overall and surgical costs, until a proficiency threshold was attained., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Management of degenerative disease of the spine has evolved to favor minimally invasive techniques, including nonrobotic-assisted and robotic-assisted minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). Value-based spending is being increasingly implemented to control rising costs in the US healthcare system. With an aging population, it is fundamental to understand which procedure(s) may be most cost-effective., Objective: To compare robotic and nonrobotic MIS-TLIF through a cost-utility analysis., Methods: We considered direct medical costs related to surgical intervention and to the hospital stay, as well as 1-yr utilities. We estimated costs by assessing all cases involving adults undergoing robotic surgery at a single institution and an equal number of patients undergoing nonrobotic surgery, matched by demographic and clinical characteristics. We adopted a willingness to pay of $50 000/quality-adjusted life year (QALY). Uncertainty was addressed by deterministic and probabilistic sensitivity analyses., Results: Costs were estimated based on a total of 76 patients, including 38 undergoing robot-assisted and 38 matched patients undergoing nonrobot MIS-TLIF. Using point estimates, robotic surgery was projected to cost $21 546.80 and to be associated with 0.68 QALY, and nonrobotic surgery was projected to cost $22 398.98 and to be associated with 0.67 QALY. Robotic surgery was found to be more cost-effective strategy, with cost-effectiveness being sensitive operating room/materials and room costs. Probabilistic sensitivity analysis identified robotic surgery as cost-effective in 63% of simulations., Conclusion: Our results suggest that at a willingness to pay of $50 000/QALY, robotic-assisted MIS-TLIF was cost-effective in 63% of simulations. Cost-effectiveness depends on operating room and room (admission) costs, with potentially different results under distinct neurosurgical practices., (Copyright © Congress of Neurological Surgeons 2021. All rights reserved.)

We describe the operative approach and management for costotransverse joint inflammation in a 49-yr-old man with worsening midthoracic pain radiating to the right paraspinal area. He underwent physical therapy with no relief of his symptoms. Thoracic spine magnetic resonance imaging (MRI) revealed severe arthritic changes involving the right T10 costotransverse joint. Scoliosis X-rays showed a dextroconvex curvature in the midthoracic spine, without any significant imbalance. Single-photon emission computed tomography (SPECT) scan revealed focal increased uptake of the right T10 costotransverse joint. T10 costotransverse joint lidocaine injection did not provide any relief. We performed a computed tomography (CT)-guided biopsy, which was negative for malignancy and also cultures were negative. MRI revealed a significant enhancement in this area and the patient's C-reactive Protein was elevated. Decision was made to perform open biopsy and costotransverse joint resection. We present a case of minimally invasive, image-guided costotransverse joint resection, which has not been described in the literature. The right T10 costotransverse joint was dissected out with the image-guided dilator, and tubular retractors were inserted. Under the microscope, using the image-guided drill, the right T10 costotransverse joint was drilled out. The lateral aspect of the right T10 process was drilled out as well as the medial-dorsal aspect of the right T10 rib. The patient recovered from surgery well with abatement of his preoperative thoracic pain, which remained abated at 6-mo follow-up. This case highlights the complex technical nuances of this procedure, and the importance of a thorough preoperative evaluation with a bone SPECT scan to help localize the pain generator. Patient consented for the procedures and for the publication of the video., (© Congress of Neurological Surgeons 2021.)

Summary Statement: Three-dimensional (3D) printing is rapidly growing in popularity for anatomical modeling and simulation for medical organizations across the world. Although this technology provides a powerful means of creating accurately representative models of anatomic structures, there remains formidable financial and workforce barriers to understanding the fundamentals of technology use, as well as establishing a cost- and time-effective system for standardized incorporation into a workflow for simulator design and anatomical modeling. There are many factors to consider when choosing the appropriate printer and accompanying software to succeed in accomplishing the desired goals of the executing team. The authors have successfully used open-access software and desktop fused deposition modeling 3D printing methods to produce more than 1000 models for anatomical modeling and procedural simulation in a cost-effective manner. It is our aim to share our experience and thought processes of implementing 3D printing into our anatomical modeling and simulation workflow to encourage other institutions to comfortably adopt this technology into their daily routines., Competing Interests: The authors declare no conflict of interest., (Copyright © 2020 Society for Simulation in Healthcare.)

Objective: Robotic surgical systems have been developed to improve spine surgery accuracy. Studies have found significant reductions in screw revision rates and radiation exposure with robotic assistance compared with open surgery. The aim of the present study was to compare the perioperative outcomes between robot-assisted (RA) and fluoroscopically guided (FG) minimally invasive (MI) transforaminal lumbar interbody fusion (TLIF) performed by a single surgeon., Methods: The present retrospective cohort study analyzed all patients with lumbar degenerative disease who had undergone MI-TLIF by a single surgeon from July 2017 to March 2020. One group had undergone FG MI-TLIF and one group had undergone RA MI-TLIF., Results: Of the 101 patients included in the present study, 52 had undergone RA MI-TLIF and 49, FG MI-TLIF. We found no statistically significant differences in the operative time (RA, 241 ± 69.3 minutes; FG, 246.2 ± 56.3 minutes; P = 0.681). The mean radiation time for the RA group was 32.8 ± 28.8 seconds, and the mean fluoroscopy dose was 31.5 ± 30 mGy. The RA radiation exposure data were compared with similar data for the FG MI-TLIF group in a previous study (59.5 ± 60.4 mGy), with our patients' radiation exposure significantly lower (P = 0.035). The postoperative complications and rates of surgical revision were comparable., Conclusions: Our results have demonstrated that RA MI-TLIF provides perioperative outcomes comparable to those with FG MI-TLIF. A reduced radiation dose to the patient was observed with RA compared with FG MI-TLIF. No differences were noted between the RA and FG cohorts in operative times, complication rates, revision rates, or length of stay., (Published by Elsevier Inc.)

Introduction: Three-dimensional (3D) printing of anatomical structures is a growing method of education for students and medical trainees. These models are generally produced as static representations of gross surface anatomy. In order to create a model that provides educators with a tool for demonstration of kinematic and physiologic concepts in addition to surface anatomy, a high-resolution segmentation and 3D-printingtechnique was investigated for the creation of a dynamic educational model., Methods: An anonymized computed tomography scan of the cervical spine with a diagnosis of ossification of the posterior longitudinal ligament was acquired. Using a high-resolution thresholding technique, the individual facet and intervertebral spaces were separated, and models of the C3-7 vertebrae were 3D-printed. The models were placed on a myelography simulator and subjected to flexion and extension under fluoroscopy, and measurements of the spinal canal diameter were recorded and compared to in-vivo measurements. The flexible 3D-printed model was then compared to a static 3D-printed model to determine the educational benefit of demonstrating physiologic concepts., Results: The canal diameter changes on the flexible 3D-printed model accurately reflected in-vivo measurements during dynamic positioning. The flexible model also was also more successful in teaching the physiologic concepts of spinal canal changes during flexion and extension than the static 3D-printed model to a cohort of learners., Conclusions: Dynamic 3D-printed models can provide educators with a cost-effective and novel educational tool for not just instruction of surface anatomy, but also physiologic concepts through 3D ex-vivo modeling of case-specific physiologic and pathologic conditions., (© 2020 Wiley Periodicals, Inc.)

Background: Pedicle screw placement is the most common method of fixation in the thoracic spine. Use of the "superior facet rule" allows the operator to locate the borders of the pedicle reliably using posterior landmarks alone. This study investigated the ability of 3-dimensionally (3D)-printed thoracic vertebrae, made from combined thermoplastic polymers, to demonstrate pedicle screw cannulation accurately using the superior facet as a reliable landmark., Methods: An anonymized computed tomography scan of the thoracic spine was obtained. The T1-T12 thoracic vertebrae were anatomically segmented and 3D-printed. The pedicle diameters and distance from the midpoint of the superior facet to the ventral lamina were recorded. A total of 120 thoracic pedicles in 60 thoracic vertebral models were instrumented using a freehand technique based only on posterior landmarks. The vertebral models were then coronally cut and examined for medial or lateral violations of the pedicle after screw placement., Results: A total of 120 pedicle screws were placed successfully within the 3D-printed thoracic vertebral models. Average measurements fell within 1 standard deviation of previous population studies. There were no pedicle wall violations using standard posterior element landmarks for instrumentation. There were 3 lateral violations of the vertebral body wall during screw placement, all attributable to the insertion technique., Conclusions: 3D-printed thoracic vertebral models using combined thermoplastic polymers can accurately demonstrate the anatomical ultrastructure and posterior element relationships of the superior facet rule for safe thoracic pedicle screw placement. This method of vertebral model prototyping could prove useful for surgical education and demonstrating spinal anatomy., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Objective: To test the efficacy of an innovative coronavirus disease 2019 (COVID-19) preoperative triage protocol as a way to gradually reopen and ramp-up elective surgeries., Patients and Methods: We reviewed clinical, radiographic, and laboratory data for all patients who underwent surgery within the neurosurgery department from March 26 through April 22, 2020. We collected data on demographic information, comorbidities, preoperative COVID-19 test results, whether COVID-19 respiratory or other symptoms were developed during hospitalization, hospital length of stay, discharge disposition, and postoperative COVID-19 test results., Results: Using a combination of both preoperative outpatient COVID-19 drive-through and inpatient testing to obtain surgical clearance with selected telemedicine evaluations, 103 nonelective neurosurgical procedures were performed in 102 patients. No patients tested positive for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) 48 hours before surgery. None of the patients developed any COVID-19 symptoms during their hospitalization or were readmitted to our emergency department postoperatively for COVID-19 symptoms., Conclusion: We describe a multifaceted preoperative triage protocol for safely performing nonelective neurosurgical procedures during the COVID-19 pandemic, which could help other neurosurgical departments and hospitals minimize coronavirus exposure for patients and health care workers. We believe this triage strategy could be implemented at other centers to gradually restart a process toward elective surgeries in a safe way., (© 2020 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc.)

No scientific evidence on restrictions for patients following an anterior cervical discectomy and fusion (ACDF) is available. The goal of this study is to assess the practice and patterns of restrictions after single-level and multilevel ACDF at an academic institution. We submitted two questionnaires, for restrictions after single-level and multilevel ACDF, to 18 spine surgeons at our institution. Questions included length of time in practice, use of cervical collar, postoperative restrictions and practices. We received 10 complete responses. Four (40%) of the respondents were in practice for less than 5 years; 3 (30%) 5 or more years, but less than 10; 1 (10%) 10 or more years, but less than 20; 2 (20%) 20 or more years. Only two (20%) surgeons recommend a cervical collar after a single-level ACDF, while seven (70%) do so after a multilevel ACDF, for an average of 9.1 weeks and standard deviation (SD) of 2.8. Nine surgeons (90%) reported providing lifting restrictions after a single-level and multilevel ACDF, with a mean of 10 kg and SD of 2.5 in both cases. 5 (50%) give driving restrictions after a single-level ACDF, eight (80%) do so after a multilevel. eight (80%) recommend physical therapy after both single-level and multilevel ACDF. three (30%) obtain a CT to confirm fusion at one year. Only two (20%) recommend a bone stimulator. Significant variability exists among surgeons in regards to restrictions following ACDF, but some areas of consensus emerged: 90% of respondents give lifting restrictions, with a mean of 10 kg, 80% recommend physical therapy for a range of motion and muscle strengthening., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2020, De Biase et al.)

We present a surgical video highlighting the technical demonstration and microsurgical anatomy of an L4-5 transforaminal lumbar interbody fusion utilizing a combination of thermoplastic polymers and 3-dimensional printing technology to create a biomimetic lumbar spine surgical simulator. The posterior elements of L4-5 and the inferior portion of L3 are exposed in their entirety, including the transverse processes in order to identify the appropriate landmarks for pedicle screw insertion. The interspinous ligament of L4-5 is removed, and an interlaminar spreader is used to distract the facet joint. An inferior L4 facetectomy is performed for local autograft harvesting. The L4 and L5 pedicles are skeletonized to completely open the foramen in order to ensure that the exiting nerve root will not be compromised during cage insertion. The ligamentum flavum is then removed, exposing the common thecal sac and L5 traversing root. The L4 exiting nerve root is then identified, completing Kambin's triangle and location of the disc space. The disc is incised, and a combination of punches and curettes are used to completely remove the disc. After an interbody trial is used to assess the proper cage size, the cage is packed with graft and inserted into the midline of the disc space. Pedicle screws are then placed using an anatomic freehand technique, and intraoperative fluoroscopy is performed in order to evaluate the instrumentation and interbody position. If a contralateral decompression is required, a facet-sparing technique is performed in order to preserve bony surface for the fusion. Patient consent was not required for this simulation video., (Copyright © 2019 by the Congress of Neurological Surgeons.)

Introduction Cervical kyphotic deformity can be quite debilitating. Most patients present with neck pain, but they can also present with radiculopathy, myelopathy, altered vertical gaze, swallowing problems, and even cosmetic issues from the severe kyphotic deformity. After failing conservative management, surgery remains the only option for halting symptom progression. Surgical options for cervical kyphosis have included anterior-only approaches, posterior-only approaches, or 360- and 540-degree reconstructions. This paper addresses the correction of cervical kyphotic deformity via an anterior-only approach consisting of a four-level anterior cervical discectomy and fusion (ACDF). Methods We interrogated our procedure log system and the keyword "anterior cervical discectomy and fusion (ACDF)" was typed into the search bar. All patients with an ACDF for the past five years were reviewed and patients with a four-level ACDF were selected. Chart review was performed and patients presenting with multi-level cervical stenosis with kyphosis were included in the study. Pre- and post-surgery images were reviewed, and the degrees of pre-operative kyphosis and post-operative lordosis were measured. Results  Our search produced 20 patients. All the patients had a diagnosis of multi-level cervical stenosis with or without myelopathy and were all symptomatic. Pre-operative kyphosis ranged from 2.3 to 35 (mean 11.5) degrees, and post-operative lordosis ranged from 2 to 38 (mean 16) degrees. All the patients had varying degrees of kyphosis correction post-surgery which ranged from 6 to 44 (mean 27) degrees. Significant improvement or complete resolution of symptoms post-operatively occurred in all patients. Conclusion  Four-level ACDF in carefully selected patients can be used to correct cervical alignment in patients presenting with symptomatic multi-level cervical stenosis with kyphosis., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2020, Ebot et al.)

We present a surgical video highlighting the technical pearls for C7 pedicle screw placement with respect to cervicothoracic constructs. Pedicle screw placement into C7 has been shown to enhance the biomechanical stability of both cervical and cervicothoracic constructs and is safe for patient related outcomes.1,2 Rod placement across the cervicothoracic junction is known to be difficult because of the variable starting point of the C7 pedicle screw, which may cause misalignment of the polyaxial heads with respect to the C7 and C6 screw heads. Using our step-wise method of anatomic screw placement, this potential pitfall is minimized. The T1 pedicle screw is placed first. The C6 lateral mass screw starting point is displaced slightly superiorly from the midpoint of the lateral mass in order to make room for the polyaxial head of the C7 pedicle screw. A small laminotomy is performed in order to find the medial border of the C7 pedicle. Palpation of the medial border allows for an approximation of the pedicle limits. The cranial-caudal angle of drilling is perpendicular to the C7 superior facet, and the medial-lateral trajectory typically falls between 15 and 20 degrees medial. Once the pedicle is cannulated, a ball-tipped probe is used to confirm intraosseous position. A rod is cut and contoured to the appropriate length of the construct. The C7 pedicle screw should capture the rod easily with slight displacement of the polyaxial head. Postinstrumentation anteroposterior and lateral fluoroscopy are performed to confirm good position of the lateral mass and pedicle screws. Patient consent was not required for this cadaveric surgical video., (Copyright © 2019 by the Congress of Neurological Surgeons.)

Competing Interests: Competing interests: None declared.

Background The recent COVID-19 pandemic has demonstrated the need for innovation in cost-effective and easily produced surgical simulations for trainee education that are not limited by physical confines of location. This can be accomplished with the use of desktop three-dimensional (3D) printing technology. This study describes the creation of a low-cost and open-access simulation for anatomical learning and pedicle screw placement in the lumbar spine, which is termed the SpineBox. Materials and methods An anonymized CT scan of the lumbar spine was obtained and converted into 3D software files of the L1-L5 vertebral bodies. A computer-assisted design (CAD) software was used to assemble the vertebral models into a simulator unit in anatomical order to produce an easily prototyped simulator. The printed simulator was layered with foam in order to replicate soft tissue structures. The models were instrumented with pedicle screws using standard operative technique and examined under fluoroscopy. Results Ten SpineBoxes were created using a single desktop 3D printer, with accurate replication of the cortico-cancellous interface using previously validated techniques. The models were able to be instrumented with pedicle screws successfully and demonstrated quality representation of bony structures under fluoroscopy. The total cost of model production was under $10. Conclusion The SpineBox represents the first open-access simulator for the instruction of spinal anatomy and pedicle screw placement. This study aims to provide institutions across the world with an economical and feasible means of spine surgical simulation for neurosurgical trainees and to encourage other rapid prototyping laboratories to investigate innovative means of creating educational surgical platforms in the modern era., Competing Interests: Provisional patent based on the use of polymeric foam and 3D-printed ABS vertebral models for spine surgical simulation., (Copyright © 2020, Clifton et al.)

Introduction: Three-dimensional printing and virtual simulation both provide useful methods of patient-specific anatomical modeling for assessing and validating surgical techniques. A combination of these two methods for evaluating the feasibility of spinal instrumentation techniques based on anatomical landmarks has not previously been investigated., Materials and Methods: Nineteen anonymized CT scans of the thoracic spine in adult patients were acquired. Maximum pedicle width and height were recorded, and statistical analysis demonstrated normal distributions. The images were converted into standard tessellation language (STL) files, and the T12 vertebrae were anatomically segmented. The intersection of two diagonal lines drawn from the lateral and medial borders of the T12 transverse process (TP) to the lateral border of the pars and inferolateral portion of the TP was identified on both sides of each segmented vertebra. A virtual screw was created and insertion into the pedicle on each side was simulated using the proposed landmarks. The vertebral STL files were then 3D-printed, and 38 pedicles were instrumented according to the individual posterior landmarks used in the virtual investigation., Results: There were no pedicle breaches using the proposed anatomical landmarks for insertion of T12 pedicle screws in the virtual simulation component. The technique was further validated by additive manufacturing of individual T12 vertebrae and demonstrated no breaches or model failures during live instrumentation using the proposed landmarks., Conclusions: Ex vivo modeling through virtual simulation and 3D printing provides a powerful and cost-effective means of replicating vital anatomical structures for investigation of complex surgical techniques., (© 2020 Wiley Periodicals, Inc.)

Surgical proficiency is classically acquired through live experience in the operating room. Trainee exposure to cases and complex pathologies is highly variable between training programs. 1 Currently, there is no standard for neurosurgical skill assessment for specific operative techniques for trainees. Cadaveric simulation has been used to demonstrate surgical technique and assess resident skill but often presents a significant financial and facility burden. 2-4 Three-dimensional (3D) printing is an alternative to cadaveric tissue in providing high-quality representation of surgical anatomy; however, this technology has significant limitations in replicating conductive soft tissue structures for the use of cauterization devices and haptic learning for proper tissue manipulation. 5-7 Our team has combined novel synthesis methods of conductive thermoplastic polymerization and 3-dimensional-printed cervical spine models to produce a layered biomimetic simulation that provides cost-effective and anatomically accurate education for neurosurgical trainees (Video 1). This is accomplished through virtual modeling and layered simulator construction methods by placing the individual polymer layers according to anatomic location of the simulated in vivo structures. The consistency of the thermoplastics can be tailored according to the desired soft tissue structures (skin, fat, fascia, muscle) according to the degree of polymerization. This cost-effective simulation was designed to represent the material and biomechanical properties of the cervical spine cortico-cancellous interface, as well as individual soft tissue components with specific anatomic details of muscle tendinous and ligamentous insertion. These features allow for representative start-to-finish surgical simulation that has not yet been made widely available to neurosurgical training programs., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Three-dimensional (3D) printing has revolutionized medical training and patient care. Clinically it is used for patient-specific anatomical modeling with respect to surgical procedures. 3D printing is heavily implemented for simulation to provide a useful tool for anatomical knowledge and surgical techniques. Fused deposition modeling (FDM) is a commonly utilized method of 3D printing anatomical models due to its cost-effectiveness. A potential disadvantage of FDM 3D printing complex anatomical shapes is the limitations of the modeling system in providing accurate representations of multifaceted ultrastructure, such as the facets of the lumbar spine. In order to utilize FDM 3D printing methods in an efficient manner, the pre-printing G-code assembly must be oriented according to the anatomical nature of the print. This article describes the approach that our institution's 3D printing laboratory has used to manipulate models' printing angles in regard to the print bed and nozzle, according to anatomical properties, thus creating quality and cost-effective anatomical spine models for education and procedural simulation., Competing Interests: Provisional patent based on hollow FDM printed spine model for procedural simulation, (Copyright © 2020, Damon et al.)

Disorders of the spine are among the most common indications for neurosurgical and orthopedic surgical interventions. Spinal fixation in the form of pedicle screw placement is a common form of instrumentation method in the lower cervical, thoracic, and lumbar spine. A vital principle to understand for the safe and accurate placement of pedicle screws is the palpable difference between the cortical and cancellous bone, both of which have different material properties and compositions. Probing and palpation of the hard cortical bone, also known as the "ventral lamina", covering the neural elements of the spinal canal during screw placement provides manual feedback to the surgeon, indicating an impending breach if continued directional force is applied. Generally, this practice is learned at the expense of patients in live operating room scenarios. Currently, there is a paucity of human vertebra simulation designs that have been validated based on the in vivo ultrastructure and physical properties of human cortical and cancellous bone. In this study, we examined the feasibility of combining three-dimensionally printed thermoplastic polymers with polymeric foam to replicate both the vertebral corticocancellous interface and surface anatomy for procedural education.

Anterior cervical discectomy and fusion (ACDF) is a commonly performed procedure for cervical spine pathologies, with excellent arthrodesis and symptom resolution. Post-operative dysphagia is a significant concern for patients undergoing this procedure because it can significantly affect their quality of life. Studies have shown that the incidence of post-operative dysphagia increases with an increase in the number of levels performed. A retrospective chart review was performed by interrogating our procedure log system and the key words "anterior cervical discectomy and fusion" was inserted in to the search bar. All patients with a four level ACDF were selected. Chart review was performed for their speech evaluation immediate after surgery and three months post operatively. A total of 28 patients were identified for the study. Speech evaluation records were available for 21 of the 28 patients. Two of the patients had posterior instrumentation and were eliminated. There were 11 females and 8 males, average age was 62 (range 47-73), and all the patients had a C3-C7 ACDF. 2 out of the 19 (11%) patients had dysphagia diagnosed via barium swallow evaluation immediately after surgery, which persisted for 3 months. Both patients diagnosed with dysphagia were females. The Two patients were 72 and 73 years old. The incidence of post-operative dysphagia in patients undergoing 4 levels ACDF at our institution was found to be lower than the current literature quotes. Age and gender were more predictive of developing dysphagia in this study., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Anatomical knowledge is a key tenet in graduate medical and surgical education. Classically, these principles are taught in the operating room during live surgical experience. This puts both the learner and the patient at a disadvantage due to environment, time, and safety constraints. Educational adjuncts such as cadaveric courses and surgical skills didactics have been shown to improve resident confidence and proficiency in both anatomical knowledge and surgical techniques. However, the cost-effectiveness of these courses is a limiting factor and in many cases prevents implementation within institutional training programs. Anatomical simulation in the form of "desktop" three-dimensional (3D) printing provides a cost-effective adjunct while maintaining educational value. This article describes the anatomical and patient-centered approach that led to the establishment of our institution's 3D printing laboratory for anatomical and procedural education. Clin. Anat. 32:124-127, 2019. © 2019 Wiley Periodicals, Inc., (© 2019 Wiley Periodicals, Inc.)

Background: 3D printed models have grown in popularity for resident training. Currently there is a paucity of simulators specifically designed for advanced cervical instrumentation. Our institution created a unique simulator for the instruction of freehand placement of C2 laminar screws using a specific 3-dimensional printing technique to replicate the corticocancellous interface. This study was designed to determine the efficacy of the simulator for teaching neurosurgical residents the freehand technique of C2 laminar screw placement., Methods: Ten participants with different experience levels participated in the study. The participants were separated into 2 groups based on experience level. Primary outcome assessments were breach rates, screw-screw interaction, and the ability to successfully place 2 screws in 1 model. Participants were graded based on a performance scoring system, and the outcomes of the 2 groups were compared., Results: All participants in the novice group showed improved technical ability on repeated use of the simulator and were able to successfully place bilateral screws by the fourth attempt. Statistical analysis indicated an association between operative experience level and successful bilateral screw placement, implying that the simulator accurately represented an in vivo intraoperative scenario., Conclusions: By utilizing our novel 3D printing production method, we have created a unique simulator for the freehand placement of C2 laminar screws. To our knowledge, this is the first report of a study investigating the use of a 3-dimensional printed simulator specifically designed to teach the freehand placement of C2 laminar screws to neurosurgical trainees., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Atlantoaxial fusion often requires C2 nerve transection for complete C1 lateral mass exposure. Nerve transection is made ideally at the preganglionic segment proximal to the dorsal root ganglion to minimize the risk of postoperative dysesthesias. If the nerve is transected too proximally, cerebrospinal fluid leak may be encountered by violation of the dura and arachnoid where the sensory and motor nerve rootlets exit the subarachnoid space. In this study we aimed to quantify the length of the C2 nerve preganglionic segment using cadaveric specimens and develop a method for reliable intraoperative localization for sectioning during C1-2 arthrodesis., Methods: Using microsurgical techniques, 16 C2 nerves from 8 frozen and injected cadaveric cervical spine specimens were dissected. Two key measurements were taken to establish a reliable method of preganglionic segment identification. The "sweet spot" for nerve transection was based on the approximate location of the midpoint of the preganglionic segment., Results: The final determination of the ideal spot for C2 nerve transection using these calculations was 3 mm lateral to the medial border of the lateral mass., Conclusions: This anatomic study found remarkable consistency in the preganglionic segment length. The medial border of the lateral mass appeared to be a consistently reliable landmark for identification of the preganglionic segment of the C2 nerve root. By using relationships between known anatomic structures intraoperatively, safety of atlantoaxial fixation can be optimized to maximize complication avoidance and satisfactory patient outcomes., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background Three-dimensional (3D) printing is a growing practice in the medical community for patient care and trainee education as well as production of equipment and devices. The development of functional models to replicate physiologic systems of human tissue has also been explored, although to a lesser degree. Specifically, the design of 3D printed phantoms that possess comparable biomechanical properties to human cervical vertebrae is an underdeveloped area of spine research. In order to investigate the functional uses of cervical 3D printed models for replicating the complex physiologic and biomechanical properties of the human subaxial cervical spine, our institution has created a prototype that accurately reflects these properties and provides a novel method of assessing spinal canal dimensions using simulated myelography. To our knowledge, this is the first 3D printed phantom created to study these parameters. Materials and methods A de-identified cervical spine computed tomography imaging file was segmented using threshold modulation in 3D Slicer software. The subaxial vertebrae (C3-C7) of the scan were individualized by separating the facet joint spaces and uncovertebral joints within the software in order to create individual stereolithography (STL) files. Each individual vertebra was printed on an Ultimaker S5 dual-extrusion printer using white "tough" polylactic acid filament. A human cadaveric subaxial cervical spine was harvested to provide a control for our experiment. Both models were assessed and compared in flexion and extension dynamic motion grossly and fluoroscopically. The maximum angles of deformation on X-ray imaging were recorded using DICOM (Digital Imaging and Communications in Medicine) viewing software. In order to compare the ability to assess canal dimensions of the models using fluoroscopic imaging, a myelography simulation was designed. Results The cervical phantom demonstrated excellent ability to resist deformation in flexion and extension positions, attributed to the high quality of initial segmentation. The gross and fluoroscopic dynamic movement of the phantom was analogous to the cadaver model. The myelography simulator adequately demonstrated the canal dimensions in static and dynamic positions for both models. Pertinent anatomic landmarks were able to be effectively visualized for assessment of canal measurements for sagittal and transverse dimensions. Conclusions By utilizing the latest technologies in DICOM segmentation and 3D printing, our institution has created the first cervical myelography phantom for biomechanical evaluation and trainee instruction. By combining new technologies with anatomical knowledge, quality 3D printing shows great promise in becoming a standard player in the future of spinal biomechanical research., Competing Interests: The development of this model was fully disclosed to the Mayo Clinic Business Office.

Background Medical simulation is an emerging field for resident training. Three-dimensional printing has accelerated the development of models for spine surgical simulation. Previous models have utilized augmented infill ratios to simulate the density difference between cortical and cancellous bone; however, this does not fully account for differences in the material properties of these components of human vertebrae. In order to replicate the differences in both density and material characteristics for realistic spinal simulation, we created a three-dimensional model composed of multiple thermoplastic polymers. Materials and methods Three lumbar vertebrae and 20 C2 vertebrae models using an experimental dual material fabrication method were printed on an Ultimaker S5 3D printer. Assessment of model integrity during instrumentation as well as user tactile feedback were points of interest to determine prototype viability for educational and biomechanical use. The experimental cohort was compared with a control cohort consisting of a single material print, resin print, and polyurethane mold. Results Based on tactile feedback, the experimental dual material print (polylactic acid [PLA]/polyvinyl alcohol [PVA]) more accurately represented the sensation of in vivo instrumentation during pedicle probing, pedicle tapping, and screw placement. There were no instrumentation or material failures in the PLA/PVA experimental model cohort. Conclusions This feasibility study indicates that multiple material printing using PLA and PVA is a viable method to replicate the cortico-cancellous interface in vertebral models. This concept and design using our unique infill algorithm have not been yet reported in the medical literature. Further educational and biomechanical testing on our design is currently underway to establish this printing method as a new standard for spinal biomimetic modeling., Competing Interests: The authors have declared that no competing interests exist.

Background: Tumoral calcinosis has been defined as a pathological condition which presents as calcified masses around juxta-articular structures. The etiology of this pathology is still not well understood but degenerative spine diseases seem to play a role. The diagnosis of tumoral calcinosis preoperatively can prevent intraoperative confusion from unexpected findings, especially in cases where removal of the calcified mass is essential to treating the patient's symptoms, i.e. nerve compression causing radiculopathy., Case Description: We present two cases of patients who presented with spinal radiculopathy and mechanical pain. Both patients were found to have a calcified facet joint mass and underwent surgical resection of the mass combined with spinal fusion resulting in excellent symptom relief post-surgery., Conclusion: For accurate diagnosis and management of tumoral calcinosis, a high index of suspicion together with neuro imaging remains a good place to start. Intra-operative visualization of the pathology as well as permanent pathology reports is a good adjunct to confirming the diagnosis., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

OBJECT The clinical success rates of anterior cervical discectomy and fusion (ACDF) procedures are substantially reduced as more cervical levels are included in the fusion procedure. One method that has been proposed as an adjunctive technique for multilevel ACDF is the placement of screws across the facet joints ("transfacet screws"). However, the biomechanical stability imparted by transfacet screw placement (either unilaterally or bilaterally) has not been reported. Therefore, the purpose of this study was to determine the acute stability conferred by implementation of unilateral and bilateral transfacet screws to an ACDF construct. METHODS Eight C2-T1 fresh-frozen human cadaveric spines (3 female and 5 male; mean age 50 years) were tested. Three different instrumentation variants were performed on cadaveric cervical spines across C4-7: 1) ACDF with an intervertebral spacer and standard plate/screw instrumentation; 2) ACDF with an intervertebral spacer and standard plate/screw instrumentation with unilateral facet screw placement; and 3) ACDF with an intervertebral spacer and standard plate/screw instrumentation with bilateral facet screw placement. Kinetic ranges of motion in flexion-extension, lateral bending, and axial rotation at 1.5 Nm were captured after each of these procedures and were statistically analyzed for significance. RESULTS All 3 fixation scenarios produced statistically significant reductions (p < 0.05) in all 3 bending planes compared with the intact condition. The addition of a unilateral facet screw to the ACDF construct produced significant reductions at the C4-5 and C6-7 levels in lateral bending and axial rotation but not in flexion-extension motion. Bilateral facet screw fixation did not produce any statistically significant decreases in flexion-extension motion compared with unilateral facet screw fixation. However, in lateral bending, significant reductions at the C4-5 and C5-6 levels were observed with the addition of a second facet screw. The untreated, adjacent levels (C2-3, C3-4, and C7-1) did not demonstrate significant differences in range of motion. CONCLUSIONS The data demonstrated that adjunctive unilateral facet screw fixation to an ACDF construct provides significant gains in stability and should be considered a potential option for increasing the likelihood for obtaining a successful arthrodesis for multilevel ACDF procedures.

Image-guided spinal surgery has evolved rapidly in recent years. This review highlights the advances in image-guided spinal surgery during this evolution. The current literature regarding image-guided spinal surgery will be discussed. In addition, several aspects of image-guided spinal surgery will be focused on, including its learning curve and influence on operating room time, as well as its effect on surgeon radiation exposure. The accuracy of instrumentation placement with this technology and current applications will also be addressed.

Study Design: An animal model of posterolateral intertransverse process spine fusion was used., Objectives: To investigate whether recombinant human bone morphogenetic protein-2 (rhBMP-2) can overcome the adverse effects of radiation treatment (RT) on spine fusion., Summary of Background Data: Spinal metastases are common. Some of these patients are candidates for spinal cord decompression and vertebral reconstruction; however, radiation has significant adverse effects on bone healing., Methods: A posterolateral fusion model was used with rhBMP-2 or iliac crest bone graft (ICBG). Eighty one-year-old rabbits were divided into eight groups: 1) RT 14 days before surgery, rhBMP-2; 2) RT 14 days before surgery, ICBG; 3) RT 2 days after surgery, rhBMP-2; 4) RT 2 days after surgery, ICBG; 5) RT 14 days after surgery, rhBMP-2; 6) RT 14 days after surgery, ICBG; 7) no RT, rhBMP-2; 8) no RT, ICBG. Animals were killed approximately 35 days after surgery. Manual palpation was the definitive test of fusion. Biomechanical and histologic assessments were also performed., Results: All rhBMP-2 groups had significantly greater fusion rates versus respective ICBG control groups: 1 (86%) versus 2 (0%) (P = 0.005), 3 (100%) versus 4 (0%) (P < 0.0001), 5 (100%) versus 6 (0%) (P < 0.0001), and 7 (100%) versus 8 (60%) (P = 0.003). Stiffness and ultimate strength did not differ significantly between the experimental and control groups. Histologic assessment confirmed new bone formation in the fusion masses from rhBMP-2 groups., Conclusions: Use of rhBMP-2 produced a significantly greater rate of fusion compared with ICBG in a previously radiated area in an animal model, without the morbidity of ICBG harvesting and without the risk of inadvertently using autograft contaminated by micrometastases.

The authors describe the case of a traumatic C-1 ring fracture and transverse ligament injury in an otherwise healthy adult woman; the lesion was essentially untreated for 3 months and resulted in basilar invagination. On presentation 3 months postinjury, the patient complained of severe increasing suboccipital pain and a grinding sensation in her upper neck. Axial computerized tomography (CT) scans revealed a C-1 ring fracture, basilar invagination with the dens abutting the clivus, and significant lateral splaying of the C-1 lateral masses. Flexion-extension radiography demonstrated abnormal motion at the atlantoaxial junction. A unique surgical technique was used to address simultaneously the C1-2 instability, the displaced C-1 fracture, and basilar invagination without having to perform occipital fixation. The authors believe that an understanding of the mechanism of the cranial settling in this case (further splaying of the C-1 lateral masses and downward migration of the occipital condyles) permitted full reduction of the deformity; this was accomplished by performing a horizontal reduction of the C-1 lateral masses, using direct C-1 lateral mass screws, a rod compressor, and a cross-link. Postoperative CT scanning confirmed the success of reduction. The results in this report highlight a rare but important complication of untreated C-1 fracture and ligament disruption, and the authors describe a novel treatment technique with which to restore vertical alignment and preserve occipital C-1 motion. A variation of this technique may also be used to treat Type II transverse ligament injuries associated with C-1 ring fractures as an alternative to halo immobilization.

We report a case of sudden onset of deep peroneal neuropathy resulting from a ganglion cyst. Electrophysiology demonstrated a severe deep peroneal neuropathy with axonal loss and probably proximal conduction block. Magnetic resonance imaging demonstrated a mass arising from the proximal tibiofibular joint extending along the peroneal nerve. Surgical resection of the ganglion resulted in gradual improvement of strength. Peroneal nerve ganglia should be considered in the evaluation of patients with sudden painless foot drop.

In this article the authors review the history of anterior cervical plating for one- and two-level discectomy for degenerative disease and provide background justification for the design and testing of a cervical plate composed of a resorbable material. The design of the plate is discussed with special reference to modifications of its design and tools compared with metallic plates that are necessary because of the different mechanical properties of the less rigid material. The cadaveric and animal in vivo testing methodologies are described, and a novel testing method for reliably quantifying graft containment is also described. Data from a representative sample are presented. Advantages and disadvantages of resorbable plating are discussed.

The authors report on the case of a 29-year-old man who presented with new-onset, generalized tonic-clonic seizures 11 years after being treated with a halo orthosis for a neurologically intact C-7 fracture. Neuroimaging and surgical findings indicated that the epileptic focus was scar tissue, which developed secondary to halo pin penetration of the skull. This complication of halo orthosis has not yet been reported in the literature.