Clinical and radiological outcomes of a cervical cage with integrated fixation

Cervical cages with integrated fixation have been increasingly used in anterior cervical discectomy and fusion (ACDF) to avoid complications associated with anterior cervical plates. The purpose of this paper is to provide 2-year follow-up results of a prospective study after implantation of a cervical cage with an integrated fixation system.This was a prospective multicenter outcome study of 90 patients who underwent ACDF with a cage with integrated fixation. Fusion was evaluated from computed tomography images (CT-images) by an independent laboratory at 2-year follow-up (FU). Clinical and radiological findings were recorded preoperatively and at FU visits and complications were reported.At 24 months, the fusion rate was 93.4%. All average clinical outcomes were significantly improved at 2 years FU compared to baseline: neck disability index (NDI) 18.9% vs 44.4%, visual analog scale (VAS) for arm pain 18.2 mm vs 61.9 mm, VAS for neck pain 23.9 mm vs 55.6 mm. Short form-36 (SF-36) scores were significantly improved. One case of dysphagia, which resolved within 12 months, and 1 reoperation for symptomatic pseudarthrosis were reported. Subsidence with no clinical consequence or reoperation was reported for 5/125 of the implanted cages (4%). There was also 1 case of per-operative vertebral body fracture that did not require additional surgery. Superior and inferior adjacent discs showed no significant change of motion at 2-year FU compared to baseline. Disc height index (DHI) and lordosis were enhanced and these improvements were maintained at 1 year.The ACDF using cages with an integrated fixation system demonstrated reliable clinical and radiological outcomes and a high interbody fusion rate. This rate is comparable to the rate reported in recent series using other implants with integrated fixation, but the present device had a lower complication rate.

C1 fracture: Analysis of consolidation and complications rates in a prospective multicenter series

INTRODUCTION

Three types of C1 fracture have been described, according to location: type 1 (anterior or posterior arc), type 2 (Jefferson: anterior and posterior arc), and type 3 (lateral mass). Stability depends on transverse ligament integrity. The main aim of the present study was to analyze complications and consolidation rates according to fracture type, age and treatment.

MATERIAL AND METHODS

The French Society of Spinal Surgery (SFCR) performed a multicenter prospective study on C1-C2 trauma. All patients with recent fracture diagnosed on CT were included. Consolidation on CT was studied at 3 months and 1 year. Medical, neurologic, infectious and mechanical complications were inventoried using the KEOPS data-base.

RESULTS

Sixty-three of the 417 patients (15.1%) had C1 fracture: type 1 (33.3%), type 2 (38.1%), or type 3 (28.6%). The transverse ligament was intact in 53.9% of cases. Treatment was non-operative in 63.5% of cases, surgical in 27.0%, and surgical after failure of non-operative treatment in 9.5%. There were 8 medical complications, more frequently in patients aged >70 years, following surgery (p<0.0001). The consolidation rate was 84.2% with non-operative treatment, 100% for primary surgery, and 33.3% for secondary surgery (p=0.002). There were 10 cases of non-union, in 4.8% of type 1, 13.6% of type 2 and 33.3% of type 3 fractures (p=0.001).

CONCLUSION

Medical complications showed association with age and with type of treatment. Non-operative treatment was suited to types 1, 2 and 3 with minimal displacement and intact transverse ligament. C1-C2 fusion was suited to displaced unstable type 2 fracture. Displaced type 3 fracture incurred risk of non-union. Early surgery may be recommended.

LEVEL OF EVIDENCE

III.

Surgeon's and patient's radiation exposure during percutaneous thoraco-lumbar pedicle screw fixation: A prospective multicenter study of 100 cases

HYPOTHESIS

Percutaneous pedicle screw fixations (PPSF) are increasingly used in spine surgery, minimizing morbidity through less muscle breakdown but at the cost of intraoperative fluoroscopic guidance that generates high radiation exposure. Few studies have been conducted to measure them accurately.

MATERIAL AND METHODS

The objective of our study is to quantify, during a PPSF carried out in different experimented centers respecting current radiation protection recommendations, this irradiation at the level of the surgeon and the patient. We have prospectively included 100 FPVP procedures for which we have collected radiation doses from the main operator. For each procedure, the doses of whole-body radiation, lens and extremities were measured.

RESULTS

Our results show a mean whole body, extremity and lens exposure dose per procedure reaching 1.7±2.8μSv, 204.7±260.9μSv and 30.5±25.9μSv, respectively. According to these values, the exposure of the surgeon's extremities and lens will exceed the annual limit allowed by the International Commission on Radiological Protection (ICRP) after 2440 and 4840 procedures respectively.

CONCLUSION

Recent European guidelines will reduce the maximum annual exposure dose from 150 to 20mSv. The number of surgical procedures to not reach the eye threshold, according to our results, should not exceed 645 procedures per year. Pending the democratization of neuronavigation systems, the use of conventional fluoroscopy exposes the eyes in the first place. Therefore they must be protected by leaded glasses.

LEVEL OF PROOF

IV, case series.

A Novel Translational Model of Spinal Cord Injury in Nonhuman Primate

Spinal cord injuries (SCI) lead to major disabilities affecting > 2.5 million people worldwide. Major shortcomings in clinical translation result from multiple factors, including species differences, development of moderately predictive animal models, and differences in methodologies between preclinical and clinical studies. To overcome these obstacles, we first conducted a comparative neuroanatomical analysis of the spinal cord between mice, Microcebus murinus (a nonhuman primate), and humans. Next, we developed and characterized a new model of lateral spinal cord hemisection in M. murinus. Over a 3-month period after SCI, we carried out a detailed, longitudinal, behavioral follow-up associated with in vivo magnetic resonance imaging (1H-MRI) monitoring. Then, we compared lesion extension and tissue alteration using 3 methods: in vivo 1H-MRI, ex vivo 1H-MRI, and classical histology. The general organization and glial cell distribution/morphology in the spinal cord of M. murinus closely resembles that of humans. Animals assessed at different stages following lateral hemisection of the spinal cord presented specific motor deficits and spinal cord tissue alterations. We also found a close correlation between 1H-MRI signal and microglia reactivity and/or associated post-trauma phenomena. Spinal cord hemisection in M. murinus provides a reliable new nonhuman primate model that can be used to promote translational research on SCI and represents a novel and more affordable alternative to larger primates.

A Combination of Ex vivo Diffusion MRI and Multiphoton to Study Microglia/Monocytes Alterations after Spinal Cord Injury

Central nervous system (CNS) injury has been observed to lead to microglia activation and monocytes infiltration at the lesion site. Ex vivo diffusion magnetic resonance imaging (diffusion MRI or DWI) allows detailed examination of CNS tissues, and recent advances in clearing procedures allow detailed imaging of fluorescent-labeled cells at high resolution. No study has yet combined ex vivo diffusion MRI and clearing procedures to establish a possible link between microglia/monocytes response and diffusion coefficient in the context of spinal cord injury (SCI). We carried out ex vivo MRI of the spinal cord at different time-points after spinal cord transection followed by tetrahydrofuran based clearing and examined the density and morphology of microglia/monocytes using two-photon microscopy. Quantitative analysis revealed an early marked increase in microglial/monocytes density that is associated with an increase in the extension of the lesion measured using diffusion MRI. Morphological examination of microglia/monocytes somata at the lesion site revealed a significant increase in their surface area and volume as early as 72 hours post-injury. Time-course analysis showed differential microglial/monocytes response rostral and caudal to the lesion site. Microglia/monocytes showed a decrease in reactivity over time caudal to the lesion site, but an increase was observed rostrally. Direct comparison of microglia/monocytes morphology, obtained through multiphoton, and the longitudinal apparent diffusion coefficient (ADC), measured with diffusion MRI, highlighted that axonal integrity does not correlate with the density of microglia/monocytes or their somata morphology. We emphasize that differential microglial/monocytes reactivity rostral and caudal to the lesion site may thus coincide, at least partially, with reported temporal differences in debris clearance. Our study demonstrates that the combination of ex vivo diffusion MRI and two-photon microscopy may be used to follow structural tissue alteration. Lesion extension coincides with microglia/monocytes density; however, a direct relationship between ADC and microglia/monocytes density and morphology was not observed. We highlighted a differential rostro-caudal microglia/monocytes reactivity that may correspond to a temporal difference in debris clearance and axonal integrity. Thus, potential therapeutic strategies targeting microglia/monocytes after SCI may need to be adjusted not only with the time after injury but also relative to the location to the lesion site.

Instrumented Circumferential Fusion in Two Stages for Instable Lumbar Fracture: Long-Term Results of a Series of 74 Patients on Sagittal Balance and Functional Outcomes

OBJECTIVE

To report the radiologic and functional results of a multicenter, prospective case series of patients with comminuted lumbar fractures treated with 2-stage circumferential arthrodesis.

METHODS

A multicenter prospective case series of 74 patients with comminuted lumbar fractures was analyzed. The strategy entailed initial posterior osteosynthesis, followed by physical replacement with an expandable titanium cage filled with autologous bone via retroperitoneal lumbotomy. The mechanism of lesion formation and epidemiologic characteristics were recorded. Clinical and quality-of-life analyses (visual analog scale [VAS], Oswesty Disability Index [ODI], Short Form 12 [SF-12]) were performed over a minimum observation period of 1 year. Radiologic parameters, including deformity measurements, were recorded at each evaluation. Fusion was analyzed by means of a 1-year monitoring scan.

RESULTS

The mean patient age was 38.1 years, and median duration of follow-up was 2.1 years (interquartile range, 1.3-2.9). The distribution of fractures according to the Magerl classification scheme was as follows: A, 64.8%; B, 16.7%; C, 18.5%. At the last follow-up, fusion was considered certain in 57 cases (77%). The mean VAS score was 2.1 ± 1.3, mean ODI was 14.7 ± 8.0, mean SF-12 Physical Component Summary score was 43.2 ± 9.3, and mean SF-12 Mental Component Summary score was 50.8 ± 5.9. Correction of the regional sagittal deformity was significant during the postoperative period, with a mean increase in lordosis of 9.0° (P < 0.0001). The loss of mean correction at the last follow-up (-2.9°) was not significant.

CONCLUSIONS

Circumferential arthrodesis, including posterior osteosynthesis and physical replacement with an expandable cage and autologous graft, is applicable to the treatment of comminuted lumbar fractures. A high rate of fusion was obtained with significant and long-lasting correction of the sagittal deformity. Functional scores measured at 1 year suggest mild disability. The ODI, SF-12, and VAS scores were positively correlated with fusion at the last follow-up.

RNA-Seq Analysis of Microglia Reveals Time-Dependent Activation of Specific Genetic Programs following Spinal Cord Injury

Neurons have inherent competence to regrow following injury, although not spontaneously. Spinal cord injury (SCI) induces a pronounced neuroinflammation driven by resident microglia and infiltrating peripheral macrophages. Microglia are the first reactive glial population after SCI and participate in recruitment of monocyte-derived macrophages to the lesion site. Both positive and negative influence of microglia and macrophages on axonal regeneration had been reported after SCI, raising the issue whether their response depends on time post-lesion or different lesion severity. We analyzed molecular alterations in microglia at several time-points after different SCI severities using RNA-sequencing. We demonstrate that activation of microglia is time-dependent post-injury but is independent of lesion severity. Early transcriptomic response of microglia after SCI involves proliferation and neuroprotection, which is then switched to neuroinflammation at later stages. Moreover, SCI induces an autologous microglial expression of astrocytic markers with over 6% of microglia expressing glial fibrillary acidic protein and vimentin from as early as 72 h post-lesion and up to 6 weeks after injury. We also identified the potential involvement of DNA damage and in particular tumor suppressor gene breast cancer susceptibility gene 1 (Brca1) in microglia after SCI. Finally, we established that BRCA1 protein is specifically expressed in non-human primate spinal microglia and is upregulated after SCI. Our data provide the first transcriptomic analysis of microglia at multiple stages after different SCI severities. Injury-induced microglia expression of astrocytic markers at RNA and protein levels demonstrates novel insights into microglia plasticity. Finally, increased microglia expression of BRCA1 in rodents and non-human primate model of SCI, suggests the involvement of oncogenic proteins after CNS lesion.

From stereoscopic recording to virtual reality headsets: Designing a new way to learn surgery

OBJECTIVE

To improve surgical practice, there are several different approaches to simulation. Due to wearable technologies, recording 3D movies is now easy. The development of a virtual reality headset allows imagining a different way of watching these videos: using dedicated software to increase interactivity in a 3D immersive experience. The objective was to record 3D movies via a main surgeon's perspective, to watch files using virtual reality headsets and to validate pedagogic interest.

MATERIAL AND METHODS

Surgical procedures were recorded using a system combining two side-by-side cameras placed on a helmet. We added two LEDs just below the cameras to enhance luminosity. Two files were obtained in mp4 format and edited using dedicated software to create 3D movies. Files obtained were then played using a virtual reality headset. Surgeons who tried the immersive experience completed a questionnaire to evaluate the interest of this procedure for surgical learning.

RESULTS

Twenty surgical procedures were recorded. The movies capture a scene which is extended 180° horizontally and 90° vertically. The immersive experience created by the device conveys a genuine feeling of being in the operating room and seeing the procedure first-hand through the eyes of the main surgeon. All surgeons indicated that they believe in pedagogical interest of this method.

CONCLUSIONS

We succeeded in recording the main surgeon's point of view in 3D and watch it on a virtual reality headset. This new approach enhances the understanding of surgery; most of the surgeons appreciated its pedagogic value. This method could be an effective learning tool in the future.

Spinal Cervical Meningiomas: The Challenge Posed by Ventral Location

OBJECTIVE

To evaluate the incidence, clinical presentation, operative techniques, and long-term outcome of spinal cervical meningiomas after surgery.

METHODS

Twenty-two patients harboring spinal meningiomas on cervical region were treated between 2004 and 2014 in our department. Diagnosis was made via magnetic resonance imaging and confirmed histologically. Microsurgical resection was performed through different surgical approaches according to location of the tumor. To remove the tumor, the posterior, far-lateral, and combined approaches were used, respectively, in 13 patients (56%), 8 patients (35%), and 2 patients (9%).

RESULTS

The mean follow-up was 40 ± 26.5 months. The most common site of dural attachment of meningioma was ventral or ventrolateral to the spinal cord. Macroscopic resection was considered complete in 55% of cases. Neurologic improvement was observed in 60% of cases. The rate of operative mortality and morbidity was high (26.5%). Five patients underwent postoperative radiotherapy according to the actual recommendation, and the overall recurrence rate was 9%.

CONCLUSIONS

Spinal meningiomas are benign tumors for which advances in imaging tools and microsurgical techniques have yielded better results. The goal of surgery should be the total resection, which significantly decreases the risk of recurrence with an acceptable morbidity. Cervical locations represent a challenge particularly for ventro and ventrolaterally located tumors. Despite the difficulty of performing a complete resection, the results obtained in this work advocate for the use of the far-lateral approach to manage meningiomas locate anterior to the neural axis.

Correlation of in vivo and ex vivo (1)H-MRI with histology in two severities of mouse spinal cord injury

Spinal cord injury (SCI) is a debilitating neuropathology with no effective treatment. Magnetic resonance imaging (MRI) technology is the only method used to assess the impact of an injury on the structure and function of the human spinal cord. Moreover, in pre-clinical SCI research, MRI is a non-invasive method with great translational potential since it provides relevant longitudinal assessment of anatomical and structural alterations induced by an injury. It is only recently that MRI techniques have been effectively used for the follow-up of SCI in rodents. However, the vast majority of these studies have been carried out on rats and when conducted in mice, the contusion injury model was predominantly chosen. Due to the remarkable potential of transgenic mice for studying the pathophysiology of SCI, we examined the use of both in and ex vivo¹H-MRI (9.4 T) in two severities of the mouse SCI (hemisection and over-hemisection) and documented their correlation with histological assessments. We demonstrated that a clear distinction between the two injury severities is possible using in and ex vivo¹H-MRI and that ex vivo MR images closely correlate with histology. Moreover, tissue modifications at a remote location from the lesion epicenter were identified by conventional ex vivo MRI analysis. Therefore, in vivo MRI has the potential to accurately identify in mice the progression of tissue alterations induced by SCI and is successfully implemented by ex vivo MRI examination. This combination of in and ex vivo MRI follow-up associated with histopathological assessment provides a valuable approach for further studies intended to evaluate therapeutic strategies on SCI.

Survey of French spine surgeons reveals significant variability in spine trauma practices in 2013

BACKGROUND

In France, attempts to define common ground during spine surgery meetings have revealed significant variability in clinical practices across different schools of surgery and the two specialities involved in spine surgery, namely, neurosurgery and orthopaedic surgery.

OBJECTIVES

To objectively characterise this variability by performing a survey based on a fictitious spine trauma case. Our working hypothesis was that significant variability existed in trauma practices and that this variability was related to a lack of strong scientific evidence in spine trauma care.

METHODS

We performed a cross-sectional survey based on a clinical vignette describing a 31-year-old male with an L1 burst fracture and neurologic symptoms (numbness). Surgeons received the vignette and a 14-item questionnaire on the management of this patient. For each question, surgeons had to choose among five possible answers. Differences in answers across surgeons were assessed using the Index of Qualitative Variability (IQV), in which 0 indicates no variability and 1 maximal variability. Surgeons also received a questionnaire about their demographics and surgical experience.

RESULTS

Of 405 invited spine surgeons, 200 responded to the survey. Five questions had an IQV greater than 0.9, seven an IQV between 0.5 and 0.9, and two an IQV lower than 0.5. Variability was greatest about the need for MRI (IQV=0.93), degree of urgency (IQV=0.93), need for fusion (IQV=0.92), need for post-operative bracing (IQV=0.91), and routine removal of instrumentation (IQV=0.94). Variability was lowest for questions about the need for surgery (IQV=0.42) and use of the posterior approach (IQV=0.36). Answers were influenced by surgeon specialty, age, experience level, and type of centre.

CONCLUSION

Clinical practice regarding spine trauma varies widely in France. Little published evidence is available on which to base recommendations that would diminish this variability.

Robot-assisted spine surgery: feasibility study through a prospective case-matched analysis

PURPOSE

While image guidance and neuronavigation have enabled a more accurate placement of pedicle implants, they can inconvenience the surgeon. Robot-assisted placement of pedicle screws appears to overcome these disadvantages. However, recent data concerning the superiority of currently available robots in assisting spinal surgeons are conflicting. The aim of our study was to evaluate the percentage of accurately placed pedicle screws, inserted using a new robotic-guidance system.

METHOD

20 Patients were operated on successively by the same surgeon using robotic assistance (ROSA™, Medtech) (Rosa group 10 patients, n = 40 screws) or by the freehand conventional technique (Freehand group 10 patients, n = 50 screws). Patient characteristics as well as the duration of the operation and of exposure to X rays were recorded.

RESULTS

The mean age of patients in each group (RG and FHG) was 63 years. Mean BMI and operating time among the RG and FHG were, respectively, 26 and 27 kg/m(2), and 187 and 119 min. Accurate placement of the implant (score A and B of the Gertzbein Robbins classification) was achieved in 97.3% of patients in the RG (n = 36) and in 92% of those in the FHG (n = 50). Four implants in the RG were placed manually following failed robotic assistance.

CONCLUSION

We report a higher rate of precision with robotic as compared to the FH technique. Providing assistance by permanently monitoring the patient's movements, this image-guided tool helps more accurately pinpoint the pedicle entry point and control the trajectory. Limitations of the study include its small sized and non-randomized sample. Nevertheless, these preliminary results are encouraging for the development of new robotic techniques for spinal surgery.

Adjacent segment disease after anterior cervical interbody fusion: a multicenter retrospective study of 288 patients with long-term follow-up

INTRODUCTION

Cervical discectomy with interbody fusion is a common procedure in spinal surgery. The resultant biomechanical alterations accelerate degeneration of the adjacent segment, but the contribution of natural degeneration to adjacent segment disease is unclear.

OBJECTIVE

To assess the long-term rate of surgery to discs adjacent to cervical interbody fusion; and to assess the associated incidence of cervico-brachial neuralgia and radiological degeneration of adjacent discs.

MATERIAL AND METHOD

A multicenter retrospective study included anterior cervical discectomy patients at a minimum of 10 years' follow-up. Clinical variables comprised pain, use of analgesics and surgical revision. Functional assessment was performed on the Neck Disability Index (NDI). Radiologic degeneration was assessed on the Goffin score based on cervical spine X-ray.

RESULTS

Two hundred and eighty-eight patients were contacted and filled out the clinical questionnaire. Among the patients, 153 underwent radiological reassessment. Mean age was 46 years (range, 16-73 years). Mean follow-up was 14.5 years (12-18 years). The rate of surgical revision on a disc adjacent to the primary level was 5.9%. Frequent attacks of cervico-brachial neuralgia were reported in 20.5% of cases. Radiologic adjacent segment degeneration was found in 81.3% of cases over follow-up. There was a significant correlation between degree of radiologic adjacent segment degeneration and NDI (P=0.02).

DISCUSSION

Degeneration adjacent to discectomy/fusion is partly due to aging. The present findings, however, agree with the literature and indicate accelerated degeneration in adjacent segments. These findings should be taken into account in treatment decision-making and suggest a possible interest of more physiological surgery such as arthroplasty.

LEVEL OF EVIDENCE

IV - Multicenter retrospective study.

Paravertebral glomangioma mimicking a schwannoma

Glomus tumors are rare benign neoplasms usually arising from soft tissues. Surgical removal seems to be the best treatment. Here, we report the case of a 52-year-old female patient referred for chronicback pain, revealing a thoracic paravertebral tumor with no osseous extension. After surgical removal,this tumor turned out to be a glomangioma. Differential diagnosis with other more frequent tumors,such as schwannoma, is particularly difficult. A review of the relevant literature will be presented. A better knowledge of the natural history of those tumors, as well as the therapeutic options available, are necessary for spinal surgeons who may encounter such presentations.

Spinal cord compression due to undiagnosed thoracic meningioma following lumbar surgery in an elderly patient: a case report

As spinal surgery in elderly patients is becoming increasingly frequent, comorbidities likely to be decompensated after such procedures must be kept in mind. We report here the case of an 82-year-old woman who presented rapidly progressive spinal cord compression following lumbar surgery for radiculopathy. Investigations showed a thoracic intradural extramedullary compressive lesion, which after removal turned out to be a meningioma. We suggest that radiculopathy and non-specific degenerative modifications partially masked this lesion, and that lumbar surgery caused this acute neurological deterioration. Therefore, we advice caution in older patients among whom such ambiguous clinical presentation is frequent.

Cervical spine injuries from diving accident: a 10-year retrospective descriptive study on 64 patients

INTRODUCTION

Ninety percent of the lesions resulting from diving injuries affect the cervical spine and are potentially associated with spinal cord injuries. The objective is to determine the most frequent lesion mechanisms. Evaluate the therapeutic alternatives and the biomechanical evolution (kyphotic deformation) of diving-induced cervical spine injuries. Define epidemiological characteristics of diving injuries.

MATERIALS AND METHODS

A retrospective analysis over a period of 10 years was undertaken for patients admitted to the Department of Neurosurgery of Montpellier, France, with cervical spinal injuries due to a diving accident. Patients were re-evaluated and clinical and radiological evaluation follow-ups were done.

RESULTS

This study included 64 patients. Cervical spine injuries resulting from diving predominantly affect young male subjects. They represent 9.5% of all the cervical spine injuries. In 22% of cases, patients presented severe neurological troubles (ASIA A, B, C) at the time of admission. A surgical treatment was done in 85% of cases, mostly using an anterior cervical approach.

DISCUSSION

This is a retrospective study (type IV) with some limitations. The incidence of diving injuries in our region is one of the highest as compared to reports in the literature. Despite an increase of our surgical indications, 55% of these cases end up with a residual kyphotic deformation but there is no relationship between the severity of late vertebral deformity and high Neck Pain and Disability Scale (NPDS) scores.

LEVEL OF EVIDENCE

Level IV, retrospective study.

Isolation and culture of precursor cells from the adult human spinal cord

Our group recently provided evidence for the presence of neural stem cells and/or progenitor cells in the adult human spinal cord. In this chapter, we review materials and methods to harvest high-quality samples of thoracolumbar, lumbar, and sacral adult human spinal cord from brain-dead patients who had agreed to donate their bodies to science for therapeutic and scientific advances. The methods to culture precursor cells from the adult human spinal cord are also described.