Feasibility of High-Fidelity Simulator Models for Minimally Invasive Spine Surgery in a Resource-Limited Setting: Experience From East Africa.

BACKGROUND: Spine surgery is a rapidly evolving specialty with a continuous need to learn new skills. In resource-limited settings such as Africa, the need for training is greater. The use of simulation-based training is important in different stages of skill acquisition, especially for high-stake procedures such as spine surgery. Among the available methods of simulation, the use of synthetic models has gained popularity among trainers. METHOD: Twenty participants of a neurosurgery training course, most of whom (65%) were neurosurgery residents and fellows, were recruited. They had hands-on training sessions using a high-fidelity lumbar degenerative spine simulation model and hands-on theater experience. After this, they completed a survey to compare their experience and assess the effectiveness of the lumbar spine model in stimulating real patient and surgery experiences. RESULTS: The participants were from four African countries, and the majority were neurosurgery residents. There were varying levels of experience among the participants in minimally invasive spine surgery, with the majority either having no experience or having only observed the procedure. All the participants said that the high-fidelity lumbar spine model effectively simulated real minimally invasive spine setup and real bone haptics and was effective in learning new techniques. Most of the participants agreed that the model effectively simulated real dura and nerve roots (95%), real muscle (90%), real bleeding from bones and muscles (95%), and real cerbrospinal fluid in the subarachnoid space. Among them, 95% agreed that the model is effective in lumbar minimally invasive spine training in resource-limited settings. CONCLUSION: With the development of new and better surgical techniques, the use of high-fidelity models provides a good opportunity for learning and training, especially in resource-poor settings where there is a paucity of training facilities and personnel.

Telemedical Support Using Smartphones for Spine Surgery in Low- and Middle-Income Countries.

Objective: Low- and middle-income countries (LMICs) face many challenges compared to industrialized nations, most notably in regard to the health care system. Patients often have to travel long distances to receive medical care with few reliable transportation mechanisms. In time-critical emergencies, this is a significant disadvantage. One specialty that is particularly affected by this is spine surgery. Within this field, traumatic injuries and acutely compressive pathologies are often time-critical. Increasing global networking capabilities through internet access offers the possibility for telemedical support in remote regions. Recently, high-performance cameras and processors became available in commercially available smartphones. Due to their wide availability and ease of use, this could provide a unique opportunity to offer telemedical support in LMICs. Methods: We conducted a feasibility study with a neurosurgical institution in east Africa. To ensure telemedical support, a commercially available smartphone was selected as the experimental hardware. Preoperatively, resolution, contrast, brightness, and color reproduction were assessed under theoretical conditions using a test chart. Intraoperatively, the image quality was assessed under different conditions. In the first step, the instrumentation table was displayed, and the mentor surgeon marked an instrument that the mentee surgeon should recognize correctly. In the next evaluation step, the surgical field was shown on film and the mentor surgeon marked an anatomical structure, and in the last evaluation step, the screen of the X-ray machine was captured, and the mentor surgeon again marked an anatomical structure. Subjective image quality was rated by two independent reviewers using the similar modified Likert scale as before on a scale of 1-5, with 1 indicating inadequate quality and 5 indicating excellent quality. Results: The image quality during the video calls was rated as sufficient overall. When evaluating the test charts, a quality of 97% ± 5 on average was found for the chart with the white background and a quality of 84% ± 5 on average for the chart with the black background. The color reproduction, the contrast, and the reproduction of brightness were rated excellent. Intraoperatively, the visualization of the instrument table was also rated excellent. Visualization of the operative site was rated 1.5 ± 0.5 on average and it was not possible to recognize relevant anatomical structures with the required confidence for surgical procedures. Image quality of the X-ray screen was rated 1.5 ± 0.9 on average. Conclusion: Current generation smartphones have high imaging performance, high computing power, and excellent connectivity. However, relevant anatomical structures during spine surgery procedures and on the X-ray screen in the operating room could not be identified with reliability to provide adequate surgical support. Nevertheless, our study showed the potential in smartphones supporting surgical procedures in LMICs, which could be helpful in other surgical fields.

Use of a High-Fidelity Training Simulator for Minimally Invasive Lumbar Decompression Increases Working Knowledge and Technical Skills Among Orthopedic and Neurosurgical Trainees.

STUDY DESIGN: Prospective comparative study. OBJECTIVE: To quantify the educational benefit to surgical trainees of using a high-fidelity simulator to perform minimally invasive (MIS) unilateral laminotomy for bilateral decompression (ULBD) for lumbar stenosis. METHODS: Twelve orthopedic and neurologic surgery residents performed three MIS ULBD procedures over 2 weeks on a simulator guided by established AO Spine metrics. Video recording of each surgery was rated by three blinded, independent experts using a global rating scale. The learning curve was evaluated with attention to technical skills, skipped steps, occurrence of errors, and timing. A knowledge gap analysis evaluating participants' current vs desired ability was performed after each trial. RESULTS: From trial 1 to 3, there was a decrease in average procedural time by 31.7 minutes. The cumulative number of skipped steps and surgical errors decreased from 25 to 6 and 24 to 6, respectively. Overall surgical proficiency improved as indicated by video rating of efficiency and smoothness of surgical maneuvers, most notably with knowledge and handling of instruments. The greatest changes were noted in junior rather than senior residents. Average knowledge gap analysis significantly decreased by 30% from the first to last trial (P = .001), signifying trainees performed closer to their desired technical goal. CONCLUSION: Procedural metrics for minimally invasive ULBD in combination with a realistic surgical simulator can be used to improve the skills and confidence of trainees. Surgical simulation may offer an important educational complement to traditional methods of skill acquisition and should be explored further with other MIS techniques.

Excessive Fluid in the Lumbar Facet Joint as a Predictor of Radiological Outcomes After Lateral Lumbar Interbody Fusion.

Background Preoperative segmental instability maybe a predictor of postoperative outcomes when treated with lateral lumbar interbody fusion (LLIF). An abnormal collection of fluid within the facet joint has been described as a sign of segmental instability. The potential relationship between this radiological sign and its prognostic relevance for indirect decompression (ID) has not been investigated. Methods Clinical and radiologic results from patients undergoing LLIF in a single institution between 2007 and 2014 were evaluated retrospectively. Patients were divided into two groups: those presenting with excessive fluid (EF) in the facet joints on T2-MRI and those with a normal amount of facet fluid with less than 1mm, which were controls. Radiological parameters were foraminal height, disc height, Cobb angle, and lumbar lordosis. Results A total of 21 patients (43 operated levels) were evaluated pre- and postoperatively. Mean disc height, mean foraminal height, and coronal Cobb angles were statistically significantly improved after LLIF. Only the EF group showed significant improvement in radiological markers after ID; the mean disc height improved from 5.5±2 to 8.8±1mm (p=0.001), mean foraminal height improved from 16.88±3 to 20.53±3mm (p=0.002), and the mean Cobb angle improved from 27.7±16 to 14±13 (p=0.018). Conclusions Patients undergoing LLIF with the radiological findings of EF in the facet joints demonstrated significant improvement in radiological outcomes of ID. Further studies should validate these findings in larger data sets.

Safety and Feasibility of Augmented Reality Assistance in Minimally Invasive and Open Resection of Benign Intradural Extramedullary Tumors.

OBJECTIVE: Surgical resection of benign intradural extramedullary tumors (BIETs) is effective for appropriately selected patients. Minimally invasive surgical (MIS) techniques have been described for successful resection of BIET while minimizing soft tissue injury. Augmented reality (AR) is a promising new technology that can accurately allow for intraoperative localization from skin through the intradural compartment. We present a case series evaluating the timing, steps, and accuracy at which this technology is able to enhance BIET resection. METHODS: A protocol for MIS and open AR-guided BIET resection was developed and applied to determine the feasibility. The tumor is marked on diagnostic magnetic resonance imaging (MRI) using AR software. Intraoperatively, the planning MRI is fused with the intraoperative computed tomography. The position and size of the tumor is projected into the surgical microscope and directly into the surgeon's field of view. Intraoperative orientation is performed exclusively via navigation and AR projection. Demographic and perioperative factors were collected. RESULTS: Eight patients were enrolled. The average operative time for MIS cases was 128 ± 8 minutes and for open cases 206 ± 55 minutes. The estimated intraoperative blood loss was 97 ± 77 mL in MIS and 240 ± 206 mL in open procedures. AR tumor location and margins were considered sufficiently precise by the surgeon in every case. Neither correction of the approach trajectory nor ultrasound assistance to localize the tumor were necessary in any case. No intraoperative complications were observed. CONCLUSION: Current findings suggest that AR may be a feasible technique for tumor localization in the MIS and open resection of benign spinal extramedullary tumors.

Augmented Reality to Improve Surgical Workflow in Minimally Invasive Transforaminal Lumbar Interbody Fusion - A Feasibility Study With Case Series.

OBJECTIVE: Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is a highly reproducible procedure for the fusion of spinal segments. We recently introduced the concept of "total navigation" to improve workflow and eliminate fluoroscopy. Imageguided surgery incorporating augmented reality (AR) may further facilitate workflow. In this study, we developed and evaluated a protocol to integrate AR into the workflow of MISTLIF. METHODS: A case series of 10 patients was the basis for the evaluation of a protocol to facilitate tubular MIS-TLIF by the application of AR. Surgical TLIF landmarks were marked on a preoperative computed tomography (CT)-scan using dedicated software. This marked CT scan was fused intraoperatively with the low-dose navigation CT scan using elastic image fusion, and the markers were transferred to the intraoperative scan. Our experience with this workflow and the surgical outcomes were collected. RESULTS: Our AR protocol was safely implemented in all cases. The TLIF landmarks could be preoperatively planned and transferred to the intraoperative imaging. Of the 10 cases, 1 case had additionally a synovial cyst resection and in 2 cases an additional bony decompression was performed due to central stenosis. The average procedure time was 160.6 ± 31.9 minutes. The AR implementation added 1.72 ± 0.37 minutes to the overall procedure time. No complications occurred. CONCLUSION: Our findings support the idea that total navigation with AR may further facilitate the workflow, especially in cases with more complex anatomy and for teaching and training purposes. More work is needed to simplify the software and make AR integration more user-friendly.

Ten-Step 3-Dimensional-Navigated Single-Stage Lateral Surgery With Microtubular Decompression: A Case Series.

BACKGROUND: Single-stage lateral lumbar interbody fusion is a safe and effective procedure that relies on indirect decompression and fusion to treat various lumbar pathologies. This technique, however, has an overall 9% rate of indirect decompression failure, which may require additional surgery to achieve adequate direct decompression. To address this concern, we modified this technique by adding a minimally invasive, direct tubular decompression in lateral position when indicated. No study has described the technical nuances of incorporating a microtubular decompression into the single-stage lateral lumbar interbody fusion workflow (SSLLIF+). OBJECTIVE: To report on the procedural steps and clinical outcomes of the SSLLIF+. METHODS: In this retrospective case series of prospectively collected data, we present the detailed surgical approach of the SSLLIF+ with a single-center case series over a 5-year period. Surgical and clinical outcomes are presented. RESULTS: A total of 7 patients underwent a SSLLIF+ with a total of 18 levels fused and 7 levels decompressed. The SSLLIF+ was successfully performed in all cases without the occurrence of intraoperative complications in this case series. There was 1 revision after 20 months of follow-up because of adjacent segment disease. There was no need for further direct decompression in a delayed fashion. CONCLUSION: SSLLIF with direct microtubular decompression in lateral position is a safe and effective procedure in patients where indirect decompression alone may not achieve the surgical goal. Adherence to minimally invasive spine surgery principles and thoughtful patient selection facilitate the successful management of these patients while demonstrating short hospital stay and low-risk of perioperative complications.

Microsurgical Tubular Resection of Intradural Extramedullary Spinal Tumors With 3-Dimensional-Navigated Localization.

BACKGROUND: The safety and efficacy of minimally invasive spine surgical (MISS) approaches have stimulated interest in adapting MISS principles for more complex pathology including intradural extramedullary (IDEM) tumors. No study has characterized a repeatable approach integrating the MISS surgical technique and 3-dimensional intraoperative navigated localization for the treatment of IDEM tumors. OBJECTIVE: To describe a safe and reproducible technical guide for the navigated MISS technique for the treatment of benign intradural and extradural spinal tumors. METHODS: Retrospective review of prospectively collected data on 20 patients who underwent navigated microsurgical tubular resection of intradural extramedullary tumors over a 5-year period. We review our approach to patient selection and report demographic and outcomes data for the cohort. RESULTS: Our experience demonstrates technical feasibility and safety with a 100% rate of gross total resection with no patients demonstrating recurrence during an average follow-up of 20.2 months and no instances of perioperative complications. We demonstrate favorable outcomes regarding blood loss, operative duration, and hospital length of stay. CONCLUSION: Navigated localization and microsurgical tubular resection of IDEM tumors is safe and effective. Adherence to MISS principles and thoughtful patient selection facilitate successful management of these patients.

Feasibility of smart glasses in supporting spinal surgical procedures in low- and middle-income countries: experiences from East Africa.

OBJECTIVE: Telemedicine technology has been developed to allow surgeons in countries with limited resources to access expert technical guidance during surgical procedures. The authors report their initial experience using state-of-the-art wearable smart glasses with wireless capability to transmit intraoperative video content during spine surgery from sub-Saharan Africa to experts in the US. METHODS: A novel smart glasses system with integrated camera and microphone was worn by a spine surgeon in Dar es Salaam, Tanzania, during 3 scoliosis correction surgeries. The images were transmitted wirelessly through a compatible software system to a computer viewed by a group of fellowship-trained spine surgeons in New York City. Visual clarity was determined using a modified Snellen chart, and a percentage score was determined on the smallest line that could be read from the 8-line chart on white and black backgrounds. A 1- to 5-point scale (from 1 = unrecognizable to 5 = optimal clarity) was used to score other visual metrics assessed using a color test card including hue, contrast, and brightness. The same scoring system was used by the group to reach a consensus on visual quality of 3 intraoperative points including instruments, radiographs (ability to see pedicle screws relative to bony anatomy), and intraoperative surgical field (ability to identify bony landmarks such as transverse processes, pedicle screw starting point, laminar edge). RESULTS: All surgeries accomplished the defined goals safely with no intraoperative complications. The average download and upload connection speeds achieved in Dar es Salaam were 45.21 and 58.89 Mbps, respectively. Visual clarity with the modified white and black Snellen chart was 70.8% and 62.5%, respectively. The average scores for hue, contrast, and brightness were 2.67, 3.33, and 2.67, respectively. Visualization quality of instruments, radiographs, and intraoperative surgical field were 3.67, 1, and 1, respectively. CONCLUSIONS: Application of smart glasses for telemedicine offers a promising tool for surgical education and remote training, especially in low- and middle-income countries. However, this study highlights some limitations of this technology, including optical resolution, intraoperative lighting, and internet connection challenges. With continued collaboration between clinicians and industry, future iterations of smart glasses technology will need to address these issues to stimulate robust clinical utilization.

Lumbar Giant Disk Herniations Treated With a Unilateral Approach for Bilateral Decompression.

BACKGROUND: Disk herniations that obstruct the spinal canal by more than 50% are named "giant disk herniations" (GDHs). GDHs are challenging to treat from a surgical perspective because of their size and the risk of iatrogenic manipulation during resection resulting in additional neurological compromise. As a result, the appropriateness of minimally invasive tubular approaches for the treatment of lumbar GDHs remains controversial. OBJECTIVE: To report our experience in treating lumbar GDHs using tubular minimally invasive surgery. METHODS: A total number of 228 disk herniations were evaluated for the criteria of GDH. In addition, the presence of neurological deficits such as cauda equina syndrome, pain as measured by a visual analog scale, operating time, complications, estimated intraoperative blood loss, and number of surgical revisions were assessed. The standard tubular diskectomy technique was modified to include unilateral laminectomy for bilateral decompression before the diskectomy to create a sufficient working space for removal of the disk fragments. RESULTS: Twenty-three (10%) patients met the criteria for GDH. Clinically significant motor weakness was present in 21 patients (91.3%) before surgery, and 3 patients (13%) presented with cauda equina syndrome. The average mean visual analog scale (±SD) for the preoperative pain score was 8.3 and decreased to 2.4 at follow-up after surgery. All cases of cauda equina syndrome resolved postoperatively. CONCLUSION: Unilateral tubular minimally invasive surgery diskectomy seems to be a safe and effective treatment alternative for lumbar GDHs, combined with the "over-the-top" decompression, which provides bilateral decompression and working space.

Treatment of Odontoid Fractures in Elderly Patients Using C1/C2 Instrumented Fusion Supplemented With Bilateral Atlantoaxial Joint Spacers: A Case Series.

BACKGROUND: Spinal fractures are among the most common traumatic injuries in elderly patients, with the odontoid process being frequently affected. As this patient group usually has high rates of comorbidity and chronic diseases, a nonoperative approach may offer a reasonable solution for a favorable fracture pattern. OBJECTIVE: We modified the procedure by implanting a bilateral atlantoaxial joint spacer (model DTRAX) into the joint space and review our experience utilizing this technique for the treatment of patients with a fracture of the odontoid process. METHODS: A retrospective evaluation was performed on patients treated surgically for unstable traumatic fractures of the odontoid process. The stabilization was performed using a dorsal rod and screw instrumentation of the lateral mass of the atlas and the pars interarticularis of the axis. The procedure was further modified by implanting a bilateral atlantoaxial joint spacer (DTRAX) into the joint space bilaterally after the removal of the articular cartilage. Patients older than 70 years with a traumatic fracture of the odontoid process were included. Pain was assessed pre- and postoperatively using the visual analog scale (VAS). To verify fusion during follow-up, either x-ray imaging of the cervical spine or magnetic resonance imaging or computed tomography were performed. RESULTS: A total of 5 patients were included in our study. Four patients had an American Society of Anesthesiology score of 3 and 1 had a score of 4. The average duration of surgery was 187 ± 38.1 minutes. The average blood loss during the procedure was 340 ± 270 mL. The average radiological follow-up period was 21.2 ± 17.5 months. Preoperatively, the average VAS pain score was 2.3 ± 3.3. Postoperatively, the mean VAS decreased to 0.6 ± 0.9. The average follow-up period for pain was 27.2 ± 19 months. No patient showed neurological deficits before or after surgery. Follow-up demonstrated solid fusion in all cases. CONCLUSION: The fusion of the atlantoaxial joint with bilateral atlantoaxial joint spacers represents a suitable and feasible option for achieving high fusion rates in elderly patients with odontoid fractures. CLINICAL RELEVANCE: A significant percentage of patients who are treated non-operatively will experience nonunion, which may cause instability of the atlantoaxial joint. Posterior fixation with screws and rods is a treatment option, but it leaves the cartilaginous joint surface in place, which can be an impediment to the fusion process. In other cases, degenerative collapse of the C1/C2 joint can cause compression of the C2 nerve root.

Clinical Significance of Redundant Nerve Roots in Patients with Lumbar Stenosis Undergoing Minimally Invasive Tubular Decompression.

OBJECTIVE: Symptomatic lumbar spinal stenosis (LSS) is a common indication for surgery in the elderly. Preoperative radiographic evaluation of patients with LSS often reveals redundant nerve roots (RNRs). The clinical significance of RNRs is uncertain. RNRs have not been studied in the setting of minimally invasive surgery. This study investigates the relationship between RNRs and clinical outcomes after minimally invasive tubular decompression. METHODS: Chart review was performed for patients with degenerative LSS who underwent minimally invasive decompression. Preoperative magnetic resonance imaging parameters were assessed, and patient-reported outcomes were analyzed. RESULTS: Fifty-four patients underwent surgery performed at an average of 1.8 ± 0.8 spinal levels. Thirty-one patients (57%) had RNRs. Patients with RNRs were older (median = 72 years vs. 66 years, P = 0.050), had longer median symptom duration (32 months vs. 15 months, P < 0.01), and had more levels operated on (2.1 vs. 1.4; P < 0.01). The median follow-up after surgery was 2 months (range = 1.3-12 months). Preoperative and postoperative patient-reported outcomes were similar based on RNR presence. Patients without RNRs had larger lumbar cross-sectional areas (CSAs) (median = 121 mm2 vs. 95 mm2, P = 0.014) and the index-level CSA (52 mm2 vs. 34 mm2, P = 0.007). The CSA was not correlated with RNR morphology or location. CONCLUSIONS: Preoperative RNRs are associated with increased age, symptom duration, and lumbar stenosis severity. Patients improved after minimally invasive decompression regardless of RNR presence. RNR presence had no effect on short-term clinical outcomes. Further study is required to assess their long-term significance.

Single-Position Fluoroscopy-Guided Lateral Lumbar Interbody Fusion With Intraoperative Computed Tomography-Navigated Posterior Pedicle Screw Fixation: Technical Report and Literature Review.

Lateral lumbar interbody fusion (LLIF) is a powerful tool in minimally invasive spine surgery with high rates of fusion, excellent indirect decompression, and deformity correction. LLIF offers advantages compared with anterior lumbar interbody fusion including a more favorable complication profile. Traditionally, the interbody fusion is performed in the lateral position and fluoroscopy-assisted pedicle screw fixation performed with the patient repositioned prone. The evolution of both pedicle screw technology and intraoperative navigation has enhanced the feasibility of single (lateral)-position surgery. Early reports using fluoroscopy-assisted pedicle screws and computer or robotic navigation suggest this technique can be performed safely and accurately. The purpose of this brief report is to provide the technical steps, workflow, as well as pearls and pitfalls for single-position LLIF with true intraoperative computed tomography navigation-guided percutaneous pedicle screw fixation. A case example is included for illustration.

Novel MIS 3D NAV Single Step Pedicle Screw System (SSPSS): Workflow, Accuracy and Initial Clinical Experience.

STUDY DESIGN: Prospective case series. OBJECTIVE: SSPSS (single step pedicle screw system) was developed for minimally invasive spine surgery. We performed this study to report on safety, workflow, and our initial clinical experience with this novel technique. METHODS: The prospective study was conducted on patients who underwent pedicle screw fixation between October 2017 and April 2018 using a novel single step 3D navigated pedicle screw system for MIS. Outcome measurements were obtained from intraoperative computerized tomography. The images were evaluated to determine pedicle wall penetration. We used a grading system to assess the severity of the pedicle wall penetration. Breaches were classified as grade 1 (<2 mm), grade 2 (2-4 mm), or grade 3 (<4 mm),1 and as cranial, caudal, medial, and lateral. RESULTS: Our study includes 135 screws in 24 patients. SSPSS eliminated K-wires and multiple steps traditionally necessary for MIS pedicle screw insertion. The median time per screw was 2.45 minutes. 3 screws were corrected intraoperatively. Pedicle wall penetration occurred in 14 screws (10%). Grade 1 breaches occurred in 4 screws (3%) and grade 2 breaches occurred in 10 screws (7%). Lateral breaches were observed more often than medial breaches. The accuracy rate in our study was 90% (Grade 0 breach). No revision surgeries were needed and no complications occurred. CONCLUSIONS: Our study suggests that SSPSS could be a safe, accurate, and efficient tool. Our accuracy rate is comparable to that found in the literature.

Image Guidance in Spinal Surgery: A Critical Appraisal and Future Directions.

BACKGROUND: Image-guided spinal surgery (IGSS) underwent rapid development over the past decades. The goal of IGSS is to increase patient safety and improve workflow. We present an overview of the history of IGSS, illustrate its current state, and highlight future developments. Currently, IGSS requires an image set, a tracking system, and a calibration method. IMAGING: Two-dimensional images have many disadvantages as a source for navigation. Currently, the most common navigation technique is three-dimensional (3D) navigation based on cross-sectional imaging techniques such as cone-beam computed tomography (CT) or fan-beam CT. TRACKING: Electromagnetic tracking uses an electromagnetic field to localize instruments. Optical tracking using infrared cameras has currently become one of the most common tracking methods in IGSS. CALIBRATION: The three most common techniques currently used are the point-matching registration technique, the surface-matching registration technique, and the automated registration technique. FUTURE: Augmented reality (AR) describes a computer-generated image that can be superimposed onto the real-world environment. Marking pathologies and anatomical landmarks are a few examples of many possible future applications. Additionally, AR offers a wide range of possibilities in surgical training. The latest development in IGSS is robotic-assisted surgery (RAS). The presently available data on RAS are very encouraging, but further improvements of these procedures is expected. CONCLUSION: IGSS significantly evolved since its inception and is becoming a routinely used technology. In the future, IGSS will combine the advantages of "active/freehand 3D navigation" with AR and RAS and will one day find its way into all aspects of spinal surgery, not only in instrumented procedures.

Pathomechanism and Biomechanics of Degenerative Disc Disease: Features of Healthy and Degenerated Discs.

The human intervertebral disc (IVD) is a complex organ composed of fibrous and cartilaginous connective tissues, and it serves as a boundary between 2 adjacent vertebrae. It provides a limited range of motion in the torso as well as stability during axial compression, rotation, and bending. Adult IVDs have poor innate healing potential due to low vascularity and cellularity. Degenerative disc disease (DDD) generally arises from the disruption of the homeostasis maintained by the structures of the IVD, and genetic and environmental factors can accelerate the progression of the disease. Impaired cell metabolism due to pH alteration and poor nutrition may lead to autophagy and disruption of the homeostasis within the IVD and thus plays a key role in DDD etiology. To develop regenerative therapies for degenerated discs, future studies must aim to restore both anatomical and biomechanical properties of the IVDs. The objective of this review is to give a detailed overview about anatomical, radiological, and biomechanical features of the IVDs as well as discuss the structural and functional changes that occur during the degeneration process.

Ten-Step Minimally Invasive Treatment of Lumbar Giant Disc Herniation via Unilateral Tubular Laminotomy for Bilateral Decompression: 2-Dimensional Operative Video.

Giant disc herniation (GDH) is generally defined as a lumbar disc herniation that obstructs 50% or more of the space in the spinal canal.1-3 Common treatment options for GDH include unilateral interlaminar approach, bilateral approach, or open full laminectomy.4,5 Surgical treatment of GDH may be challenging because severe bilateral compression of neural elements in the spinal canal increases the risk of iatrogenic injury to nerve roots and dura. The surgical approach can be further complicated by calcification, hardening, and dehydration of the GDH tissue. The prevailing opinion in the literature is that giant disc herniations cannot safely be treated via tubular minimally invasive approaches.5-7 In this video, we present a case of a 52-yr-old male patient with a history of progressive low back pain that radiates bilaterally from the buttocks toward the posterior legs and knees for 2 yr because of a GDH at the L4-5 level. The patient was treated via a tubular "over-the-top" minimally invasive decompression in order to first provide generous bilateral decompression of neural elements and dura.8,9 After sufficient decompression at the surgical level, the discectomy was performed via an ipsilateral piecemeal resection of the GDH. The "over-the-top" contralateral mobilization of disc herniation was also achieved with this approach, which facilitated the removal of the entire disc fragment. Patient consent was obtained prior to performing the procedure. Therefore, GDH should not be considered as a contraindication for tubular decompression when this modified technique is performed.

Intraoperative Simulation: Team Training for Resuscitation While Using Intraoperative Computed Tomography: 2-Dimensional Operative Video.

Spine surgeons increasingly use intraoperative computed tomography (iCT) to facilitate surgery. iCT has several advantages, including the ability to decrease radiation exposure, improve surgical accuracy, and decrease operative time.1-3 However, the large footprint of the equipment can impede fast patient access in the event of an emergency resuscitation. This challenge is compounded when the patient is prone with rigid head fixation. To achieve fast, high-quality resuscitation, a large team must overcome numerous challenges. Cohesive team functioning under these circumstances requires planning, practice, and refinement.4 As a result of our simulation sessions, we have made several changes to the setup of our iCT cases. The following equipment is now routinely used: extralong tubing between the anesthesia circuit and patient, portable vital monitor, additional intravenous access is obtained, and extension tubing is used with all lines. We have created educational diagrams to streamline 2 challenging processes: optimal bed placement (for supination) and removal of equipment from the operating room (OR) to accommodate an influx of emergency personnel and equipment. Since the implementation of this protocol, 1 prone posterior cervical patient had intraoperative cardiac arrest. The protocol was followed. Return of spontaneous circulation was achieved within 5 min. The patient was discharged from the hospital with no neurological sequelae. During debriefing, stakeholders uniformly credited the simulated practice with this positive outcome. Emergency planning is a multifaceted process that continually evolves. With a steady flux of personnel and equipment, ongoing practice is essential to ensure readiness. Here, we share the key elements of our twice-yearly simulation. This simulation was performed on a training mannequin. This study did not involve human subjects. Any depictions of care rendered to nonidentifiable patients were standard (nonexperimental).

Elastic Image Fusion Software to Coregister Preoperatively Planned Pedicle Screws With Intraoperative Computed Tomography Data for Image-Guided Spinal Surgery.

BACKGROUND: For complex spinal cases, especially when robotic guidance is used, preoperative planning of pedicle screws can be helpful. Transfer of these preoperatively planned pedicle screws to intraoperative 3-dimensional imaging is challenging because of changes in anatomic alignment between preoperative supine and intraoperative prone imaging, especially when multiple levels are involved. In the spine, where each individual vertebra is subject to independent movement from adjacent level, rigid image fusion is confined to a single vertebra and can display fusion inaccuracies on adjacent levels. A novel elastic fusion algorithm is introduced to overcome these disadvantages. This study aimed to investigate image registration accuracy of preoperatively planned pedicle screws with an elastic fusion algorithm vs. rigid fusion for intraoperative placement with image-guided surgery. METHODS: A total of 12 patients, were selected depending on the availability of a preoperative spinal computed tomography (CT) and an intraoperative AIRO CT scan (BrainLAB AG, Munich, Germany) of the same spinal region. To verify accuracy differences between rigid fusion and elastic fusion 76 bilateral screw trajectories were virtually defined in the preoperative CT image, and they were transferred via either rigid fusion or elastic fusion to the intraoperative CT scan. Accuracy of the transferred screws in the rigid and elastic fusion group was determined by measuring pedicle breaches on the intraoperative CT. RESULTS: In the rigid fusion group 1.3% of screws showed a breach of less than 2 mm, 9.2% showed breaches between 2 and 4 mm, and 18.4% of the screws showed an error above 4 mm. The elastic fusion group showed no breaches and provided high accuracy between preoperative and intraoperative screw placement. CONCLUSION: Elastic fusion provides high registration accuracy and represents a considerable step towards efficiency and safety in CT-based image-guided surgery. LEVEL OF EVIDENCE: 3.