Cervical Spine Fixation Research Articles

Lateral Mass Screw Fixation in the Cervical Spine

Lateral mass screw fixation with plates or rods has become the standard method of posterior cervical spine fixation and stabilization for a variety of surgical indications. Despite ubiquitous usage, the safety and efficacy of this technique have not yet been established sufficiently to permit "on-label" U.S. Food and Drug Administration approval for lateral mass screw fixation systems. The purpose of this study was to describe the safety profile and effectiveness of such systems when used in stabilizing the posterior cervical spine. A systematic search was conducted in MEDLINE and the Cochrane Collaboration Library for articles published from January 1, 1980, to December 1, 2011. We included all articles evaluating safety and/or clinical outcomes in adult patients undergoing posterior cervical subaxial fusion utilizing lateral mass instrumentation with plates or rods for degenerative disease (spondylosis), trauma, deformity, inflammatory disease, and revision surgery that satisfied our a priori inclusion and exclusion criteria. Twenty articles (two retrospective comparative studies and eighteen case series) satisfied the inclusion and exclusion criteria and were included. Both of the comparative studies involved comparison of lateral mass screw fixation with wiring and indicated that the risk of complications was comparable between treatments (range, 0% to 7.1% compared with 0% to 6.3%, respectively). In one study, the fusion rate reported in the screw fixation group (100%) was similar to that in the wiring group (97%). Complication risks following lateral mass screw fixation were low across the eighteen case series. Nerve root injury attributed to screw placement occurred in 1.0% (95% confidence interval, 0.3% to 1.6%) of patients. No cases of vertebral artery injury were reported. Instrumentation complications such as screw or rod pullout, screw or plate breakage, and screw loosening occurred in <1% of the screws inserted. Fusion was achieved in 97.0% of patients across nine case series. The risks of complications were low and the fusion rate was high when lateral mass screw fixation was used in patients undergoing posterior cervical subaxial fusion. Nerve root injury attributed to screw placement occurred in only 1% of 1041 patients. No cases of vertebral artery injury were identified in 758 patients. Screw or rod pullout, screw or plate breakage, and screw loosening occurred in <1% of the screws inserted.

Editorial: Occipitocervical fixation

For several reasons, occipitocervical fixation is a challenging surgical exercise. The procedure is performed infrequently, and the risks can be substantial. Vertebral artery injury can be catastrophic, bleeding during dissection can be a nuisance, and screw placement is often difficult. Surgery is even more complicated when the normal anatomy is obscured, or even missing. When this situation arises, novel techniques that have been well thought out can be a lifesaver for the practicing surgeon. The authors of “Occipital condyle to cervical spine fixation in the pediatric population” have provided a useful solution to one such problem: How does the surgeon fixate to the skull if the anatomy is compromised, or not there?3 The authors looked to the cadaver lab and previous clinical experience for a solution. The problem consisted of finding a location in the skull to place bilateral screws when the suboccipital area was anomalous or had been previously removed, such as in the case of a previously resected tumor or Chiari malformation surgery. The occipital condyle as a fixation point had been described in the adult,2,4–6 and in a single pediatric patient.1 Before performing this procedure in the operating room, the authors noted that the condyle had been shown to be a feasible fixation point in a previous cadaveric study.2,4 They then performed the procedure, with good success, in 4 pediatric patients who either had previous surgery or craniovertebral junction anomalies. There were no intraoperative or postoperative complications, and all 4 patients attained fusion. There are several other issues regarding this technique that deserve further emphasis. The use of intraoperative navigation cannot be overemphasized. Under the best of circumstances, cannulation of C-1 and/or C-2 is technically arduous. The task is even more challenging when the anatomy is abnormal, and downright daunting with the addition of the occipital condyle as a locus of fixation. Neuronavigation, such as with the O-arm or BrainLab, provides a measure of confidence and a margin for error during surgery. Feedback regarding screw placement can be obtained in real time, and screw trajectory can be altered before problems arise. Screw location and length can be assessed before the patient leaves the operating room. It is hard to imagine performing this procedure without this tool. The authors used recombinant human bone morphogenetic protein (rhBMP) to aid fusion, and justify its use by noting that 1 of the patients had previously undergone radiation treatment, and in a second patient, no decompression was necessary, and thus no local bone was available. While complication rates from iliac crest or rib harvest can be high, there are other options beside this type of autograft that are available to the surgeon. It should also be noted that there is a high rate of fusion in the pediatric population, particularly in the cervical spine. Given the current controversy surrounding the use of rhBMP, and the unknown long-term effects in children, all other options for attaining fusion should be considered in this patient cohort. Despite these concerns, this study extends our knowledge regarding the use of the occipital condyle as a site for screw placement. The authors have successfully translated a cadaveric and clinical finding to use in a specific patient population, and in the process have provided the pediatric spine surgeon another useful tool with which to successfully achieve occipitocervical fixation. (http://thejns.org/doi/abs/10.3171/2013.8.PEDS13368)

Occipital condyle to cervical spine fixation in the pediatric population

Fixation at the craniovertebral junction (CVJ) is necessary in a variety of pediatric clinical scenarios. Traditionally an occipital bone to cervical fusion is preformed, which requires a large amount of hardware to be placed on the occiput of a child. If a patient has previously undergone a posterior fossa decompression or requires a decompression at the time of the fusion procedure, it can be difficult to anchor a plate to the occipital bone. The authors propose a technique that can be used when faced with this difficult challenge by using the occipital condyle as a point of fixation for the construct. Adult cadaveric and a limited number of case studies have been published using occipital condyle (C-0) fixation. This work was adapted for the pediatric population. Between 2009 and 2012, 4 children underwent occipital condyle to axial or subaxial spine fixation. One patient had previously undergone posterior fossa surgery for tumor resection, and 1 required decompression at the time of operation. Two patients underwent preoperative deformity reduction using traction. One child had a Chiari malformation Type I. Each procedure was performed using polyaxial screw-rod constructs with intraoperative neuronavigation supplemented by a custom navigational drill guide. Smooth-shanked 3.5-mm polyaxial screws, ranging in length from 26 to 32 mm, were placed into the occipital condyles. All patients successfully underwent occipital condyle to cervical spine fixation. In 3 patients the construct extended from C-0 to C-2, and in 1 from C-0 to T-2. Patients with preoperative halo stabilization were placed in a cervical collar postoperatively. There were no new postoperative neurological deficits or vascular injuries. Each patient underwent postoperative CT, demonstrating excellent screw placement and evidence of solid fusion. Occipital condyle fixation is an effective option in pediatric patients requiring occipitocervical fusion for treatment of deformity and/or instability at the CVJ. The use of intraoperative neuronavigation allows for safe placement of screws into C-0, especially when faced with a challenging patient in whom fixation to the occipital bone is not possible or is less than ideal.

Risk factors for intraoperative lateral mass fracture of lateral mass screw fixation in the subaxial cervical spine

Although lateral mass screw fixation for the cervical spine is a safe technique, lateral mass fracture during screw fixation is occasionally encountered intraoperatively. This event is regarded as a minor complication; however, it poses difficulties in management that may affect fixation stability and clinical outcome. The purpose of this study is to determine the incidence and etiology of lateral mass fractures during cervical lateral mass screw fixation. A retrospective clinical review of patient records was performed in 117 consecutive patients (mean age 57 years, range 15-86 years) who underwent lateral mass screw fixation using a modified Magerl method from 1997 to 2010 at a single institution. A total of 555 lateral masses were included in this study. The outer diameters of the screws were 3.5 or 4.0 mm. In the retrospective clinical analysis, the incidence of intraoperative lateral mass fractures was reviewed. Potential risk factors for this complication were assessed using multivariate analysis. The incidence of lateral mass fractures during cervical lateral mass screw fixation was 4.7% (26 lateral masses) among all cases. Among the disorders, the incidence was highest in patients with destructive spondyloarthropathy (DSA) (18.8%, 12 lateral masses). There was no significant difference with respect to lateral mass fracture between the use of 4.0-mm screws (5.6%) and 3.5-mm screws (3.6%). Independent risk factors identified by logistic regression were DSA (OR 7.89, p < 0.001) and screw insertion in the C-6 lateral masses (OR 2.80, p = 0.018). The overall incidence of lateral mass fracture during cervical lateral mass screw fixation was 4.7%. Destructive spondyloarthropathy as an underlying cause of morbidity and screw placement in the C-6 lateral mass were identified as independent risk factors. Use of a 4.0-mm screw in patients with DSA may be a principal risk factor for this complication.

ECONOMIC LOSSES DUE TO ACUTE CERVICAL SPINE AND SPINAL CORD INJURY IN THE REPUBLIC OF BASHKORTOSTAN

Objective. To analyze economic losses due to acute cervical spine and spinal cord injury in the Republic of Bashkortostan. Material and Methods. Statistical data on complications after cervical spine injury were analyzed with reference to the Methodology for Estimating Economic Losses due to Mortality, Morbidity and Disability of Population. Calculation was performed for working age people involved in economics. Results. Economic losses due to cervical spine injury reach 13.5 million roubles per one victim. Conclusion. To reduce mortality and disability of victims, the need is to develop and implement an effective system for prevention of road accidents as the main cause of spinal cord injury and to introduce a point of external cervical spine fixation in the algorithm of the first aid to the accident victims regarding them as potentially having cervical spine injury. Preoperative period in patients with acute cervical spinal cord injury may be reduced through creation of interregional centres with adequate equipment and qualified staff (neurosurgeons, anesthesiologists and reanimatologists). An earlier social adaptation of patients with acute cervical spinal cord injury requires strict adherence to the principle of care continuity: hospital - rehabilitation centre – health resort – outpatient clinic.

Systematic review of the effect of dynamic fixation systems compared with rigid fixation in the anterior cervical spine

Anterior cervical fixation is a procedure widely employed in medical practice, with different fixation systems in use. This study aimed to perform a systematic review of the literature comparing the use of rigid and dynamic cervical plates regarding the fusion rate and complications. A search was conducted in PubMed, Lilacs, and Cochrane databases and selecting comparative studies on the use of rigid and dynamic cervical plates. Prospective randomized studies were selected to describe the final results regarding the clinical and radiological outcomes; comparative observational studies were also cited. Complications of using the dynamic cervical plate were also evaluated. Seven comparative studies were included in the review. Five of these were prospective and randomized studies that did not report significant differences in the clinical outcome. One study reported a faster fusion rate when dynamic cervical plate was used, and another study showed a higher fusion rate when a dynamic cervical plate was applied on multiple levels. Four studies investigated the complications of using a dynamic plate and reported that changes in the cervical curvature angle and material failure were the most frequent complications. There were no clinical differences between the two types of cervical fixation systems. A difference in the fusion rates could not be found at any follow-up time or in any of the studies. There was a loss of lordotic correction in the dynamic systems and a higher rate of complications in patients with a loss of lordotic correction.

Upper Cervical Spine Fusion in Children With Skeletal Dysplasia

Skeletal dysplasias have been associated with upper cervical instability. Many patients are initially asymptomatic, but the instability may progress to subluxation and dislocation and complications thereof, including death. Surgery is hampered by petite osseous structures and low bone formation rate. To review the outcomes of surgical fusion of upper cervical instability in children with rare skeletal dysplasias. A retrospective study of eight children with five different rare skeletal dysplasias needing upper cervical instrumented stabilization. Cases were evaluated for clinical, radiologic, and quality-of-life outcomes, with median follow-up time of 5 years. Six patients underwent posterior, segmental cervical spine instrumentation and fusion (three C1/C2 fusions, three occipitocervical fusions), one anterior cervical instrumented spinal fusion, and one anteroposterior fusion. Autogenous bone grafting was used in all patients, and seven were immobilized using a halo body jacket. Nonunion in occipitocervical fusions was common in these patients (3/8 patients). Rib autograft from occiput to cervical spine with recombinant human BMP-2 was used to salvage nonunions. Surgical fixation in the pediatric cervical spine is hampered by fragile posterior structures. A postoperative immobilization by halo vest for 4 months is customary. Selective anterior corpectomy and plate fixation is not recommended in pediatric patients with skeletal dysplasias. Level 4, Case Series.

Breaking Down Silos to Protect the Spinal Cord

Breaking Down Silos to Protect the Spinal Cord

Cervical spine instability in rheumatoid arthritis

Rheumatoid arthritis (RA) is the most common inflammatory disease of the cervical spine (CS). After hands and feet, CS is the most commonly involved segment, being present in more than half of the patients with RA. Especially in the CS, RA may cause degeneration of ligaments, leading to laxity, instability and subluxation of the vertebral bodies. This is often asymptomatic or symptoms are erroneously attributed to peripheral manifestations. Otherwise, this may cause compression of spinal cord (SC) and medulla oblongata leading to severe neurologic deficits and even sudden death. Owing to its potentially debilitating and life-threatening sequelae, inevitable progression once neurologic deficits occur and the poor medical condition of afflicted patients, CS involvement remains a priority in the diagnosis and its treatment will remain a challenge. The surgical approach aims a solid fixation of the upper cervical spine, giving stability, preventing neurologic deterioration and injury to the SC, leading to improved neurologic function, vascular integrity and maintenance of sagittal balance. The recent advances in surgical techniques, complete understanding of the anatomy and precise preoperative evaluation led to safer and more effective procedures that have decreased complication rates. Based on the fact that when a patient becomes myelopathic the rate of long-term mortality increases and the chance of neurologic recovery decreases, many authors agree that early surgical intervention, before the onset of neurologic deficits, gives a more satisfactory outcome. However, the timing when a prophylactic stabilization should occur is poorly defined, and so, patients with radiographic instability but without evidence of neurologic deficit are still the most difficult to manage.

Transfacet screw fixation of the subaxial cervical spine—how I do it?

Transfacet screw fixation is a biomechanically effective way of fusing the subaxial cervical spine. The technique used by this author is described. With the patient in prone position, a conventional posterior exposure of the cervical spine is done. The entry point used by this author is 2 mm above the middle of the lateral mass without any lateral angulation. Under fluoroscopic guidance the facet is drilled until all the four cortical surfaces are purchased. Then the depth is measured to assess the length of the screw required. This is followed by tapping and screw insertion both of which are done under fluoroscopic control. All screws are placed prior to laminectomy to decompress the cervical cord. This is a simple, inexpensive and biomechanically effective way of stabilizing the subaxial cervical spine.

Timing of tracheostomy after anterior cervical spine fixation

Patients with cervical spinal cord injury frequently undergo early anterior cervical spine fixation (ACSF) and tracheostomy procedures to reduce further deterioration, to reduce risk of pulmonary complications, and to improve patient mobilization. However, tracheostomy is often delayed because of the risk of cross contamination as a result of the proximity to the ACSF incision site. Currently, there is a paucity of studies evaluating this outcome to determine the safety of early tracheostomy after ACSF. In this study, we have evaluated the outcomes and complications associated with early tracheostomy placement. We performed a retrospective review of all patients who underwent tracheostomy placement and ACSF during the same hospitalization between 2005 and 2010. A variety of patient and procedural data were collected, including demographics, timing of ACSF and tracheostomy, length of hospitalization, indication for surgery, American Spinal Injuries Association and Glasgow Coma Scale scores on admission, reason for tracheostomy, method of tracheostomy, and complications. Of the 1,184 patients who underwent an ACSF, 20 (1.7%) required a postfixation tracheostomy. Tracheostomy was performed at mean (SD) of 6.9 (4.2) days after ACSF, ranging from 0 to 17 days. Although nearly half of all patients underwent postfixation tracheostomy within 6 days, no wound or implant infection was seen to occur in any patient. Ten patients (50%) developed ventilator-associated pneumonia, with most cases occurring before tracheostomy (90% vs. 10%, p < 0.0001). Univariate analysis only revealed late tracheostomy to significantly increase the risk of complications (odds ratio, 9.33; 95% confidence interval, 1.19-73.0; p = 0.033). Analysis of all studies in the literature revealed a 1% cross-infection rate, with no cases involving implant contamination. Our findings suggest that early tracheostomy can be performed safely after cervical spine fixation surgery, with no patients developing incisional or implant infections. As the risk of cross contamination is only 1%, early tracheostomy should be strongly considered because of its potential benefits. Therapeutic/care management, level IV.

Conservative management of esophageal perforation after a fall

INTRODUCTIONEsophageal perforation in the setting of blunt trauma is rare, and diagnosis can be difficult due to atypical signs and symptoms accompanied by distracting injury. PRESENTATION OF CASEWe present a case of esophageal perforation resulting from a fall from height. Unexplained air in the soft tissues planes posterior to the esophagus as well as subcutaneous emphysema in the absence of a pneumothorax on CT aroused clinical suspicions of an injury to the aerodigestive tract. The patient suffered multiple injuries including bilateral first rib fractures, C6 lamina fractures, C4–C6 spinous process fractures, a C7 right transverse process fracture with associated ligamentous injury and cord contusion, multiple comminuted nasal bone fractures, and a right verterbral artery dissection. Esophageal injury was localized using a gastrograffin esophagram to the cervical esophagus and was most likely secondary to cervical spine fractures. Because there were no clinical signs of sepsis and the esophagram demonstrated a contained rupture, the patient was thought to be a good candidate for a trial of conservative management consisting of broad spectrum intravenous antibiotics, oral care with chlorhexadine gluconate, NPO, and total parenteral nutrition. No cervical spine fixation or procedure was performed during this trial of conservative management. The patient was received another gastrograffin esophagram on hospital day 14 and demonstrated no evidence of contrast extravasation. DISCUSSIONEarly diagnosis and control of the infectious source are the cornerstones to successful management of esophageal perforation from all etiologies. Traditionally, esophageal perforation relied on a high index of clinical suspicion for early diagnosis, but the use of CT scan for has proved to be highly effective in diagnosing esophageal perforation especially in patients with atypical presentations. While aggressive surgical infection control is paramount in the majority of esophageal perforations, a select subset of patients can be successfully managed non-operatively. CONCLUSIONIn the setting of blunt trauma, esophageal perforation is rare and is associated with a high morbidity. In select patients who do not show any clinical signs of sepsis, contained perforations can heal with non-operative management consisting of broad spectrum antibiotics, strict oral hygiene, NPO, and total parenteral nutrition.

Clinical application of combined fixation in the cervical spine using posterior transfacet screws and pedicle screws

The aim of the present study was to describe the clinical application of combined fixation in the cervical spine using posterior transfacet and pedicle screws. Ten patients with cervical disorders requiring stabilization were treated from May 2006 to December 2008. The operative details varied depending on indication, the need for decompression, and the number of levels to be included in the spinal construct. Radiographic analysis of the fusion was performed after surgery. A total of 23 transfacet screws were inserted at or caudal to the C4/5 facet. A total of 21 pedicle screws were placed. All patients underwent operative treatment without neurovascular complications. Fusion was achieved in all patients. When performed appropriately, the method of using posterior transfacet screws in the caudal cervical joints combined with pedicle screw fixation in the cephalic cervical spine is reliable and deserves more widespread use.

Comparative study of awake endotracheal intubation with Glidescope video laryngoscope versus flexible fiber optic bronchoscope in patients with traumatic cervical spine injury

BackgroundThe Gldiescope video laryngoscope (GVL) as a recent intubating device has gained much popularity in difficult intubation over the last decade. It can be used as a substitute to flexible fiber optic bronchoscope (FOB) in intubating challenges. The object of this study is to compare the utility of GVL and FOB for intubating time, attempts, effects on hemodynamics, adverse effects, patient satisfaction and post intubation neurological outcome during awake intubation in traumatic cervical spine injury.MethodsFifty patients undergoing post traumatic cervical spine fixation under general anesthesia were randomly allocated to two groups in a prospective, controlled non-blinded study. All patients were premedicated with glycopyrrolate 0.2 mg iv and midazolam 1 mg iv that be repeated up to 0.05 mg/kg followed with a bolus dose of remifentanil 1.5 μg/kg then a continuous remifentanil infusion of 0.15 μg/kg/min for 3 min before procedure. Each patient underwent a wake endotracheal intubation with either GVL (G group) or FOB (F group) with manual in line stabilization (MILS). Intubating time, intubating attempts, hear rate (HR), mean arterial pressure (MAP), oxygen desaturation (SO2 < 90%), sore throat, patient satisfaction and postintubation neurological outcome were recorded.ResultsIntubating time was significantly lower in G group compared with F group (26 ± 5 versus 72 ± 11 respectively), while the percentage of the first successful intubating attempt was insignificantly higher in G group (88%) than in F group (72%). Both HR and MAP were significantly increased only in F group during intubation in comparison with the basal line values. Both devices were safe for post neurological outcome. No significant differences of adverse effects or patient satisfaction were recorded between groups.ConclusionThe GVL is a safe surrogate for FOB during awake intubation for post traumatic cervical spine fixation.

Successful antibiotic treatment for subdural empyema and seizure due to methicillin-resistant Staphylococcus aureus as a complication of halo orthosis usage: a case report.

Halo orthosis is used for cervical spine fixation after spinal surgery or injury. Although superficial infection at pin sites occurs frequently, intracranial development of infection, including brain abscesses, is very rare. We experienced subdural empyema due to methicillin-resistant Staphylococcus aureus (MRSA) caused by intracranial penetration of halo pins. A 38-year-old woman with a 4-year history of rheumatoid arthritis experienced severe myelopathy due to atlanto-axial dislocation and vertical subluxation. Reduction and immobilization using a halo vest resulted in neurologic improvement; she later underwent occipital bone to C2 fusion using posterior instrumentation. Three months after halo orthosis fixation, she complained of a headache, experienced a generalized tonic-clonic seizure, and became unconscious for 10min. Computed tomography revealed pneumoencephalus, and Gd-enhanced magnetic resonance imaging revealed edema, enhancement of the overlying dura in the left partial lobe, and subdural and subarachnoidal empyema. Following removal of the halo vest, there was a purulent discharge from the left-posterior pin site. Culture of the discharge was positive for MRSA. The patient was treated with intravenous vancomycin for 2weeks, followed by cefozopran hydrochloride for 4weeks. Her symptoms improved, and additional surgery was not required. At latest follow-up, 10years after the seizure, she is neurologically stable without any recurrence of the infection.

The air-Q as a conduit for fiberoptic aided tracheal intubation in adult patients undergoing cervical spine fixation: A prospective randomized study

The air-Q™ intubating laryngeal airway is a supraglottic airway device which was designed to allow adequate patient ventilation and reliable blind endotracheal tube intubation.ObjectivesTo investigate the efficacy of air-Q as a conduit for fiberoptic endotracheal intubation in adult patients with limited cervical spine mobility compared with fiberoptic-guided intubation alone.DesignProspective randomized study.PatientsSixty adult (12 female) patients, ASA physical status I and II scheduled for cervical spine fixation under general anesthesia. Patients were randomized into two parallel groups. Exclusion criteria includes, history of difficult airway, mouth opening <3 cm, Mallampati class ⩾III and, increased risk of aspiration of gastric contents.InterventionIn the first group, endotracheal intubation was aided with the fiberoptic scope while patients in the second group were intubated with the fiberoptic scope guided with the air-Q as a conduit. The number of attempts and time to successful insertion of air-Q and endotracheal tube were recorded. The fiberoptic quality of the vocal cords view as seen through the air-Q and ease of endotracheal tube insertion were also assessed.ResultsThe air-Q was easily inserted in all patients of the second group with mean insertion time (22.6 ± 4.3 s). The air-Q provided a good fiberoptic view of the vocal cords and successful tracheal intubation in 29 (96.7%) patients of the second group on the first attempt. Time to tracheal intubation in the second group was significantly shorter than the first group (21.6 ± 5.7 and 29.8 ± 6.2 s respectively). The air-Q was easily removed without any complications.ConclusionsThe air-Q as a conduit for fiberoptic scope provided a better view of the vocal cords and, less insertion time of the endotracheal compared to fiberoptic-aided endotracheal intubation in adult patients with limited cervical spine mobility scheduled for cervical spine fixation.

Lateral Mass Fixation in Subaxial Cervical Spine: Anatomic Review

Introduction The cervical spine is a highly mobile segment of the spinal column, liable to a variety of diseases and susceptible to trauma. It is a complex region where many vital structures lie in close proximity. Lateral mass screw fixation has become the method of choice in stabilizing subaxial cervical spine among other posterior cervical fixation techniques whenever the posterior elements are absent or compromised. Objective This study examined cervical specimens of cadavers and cervical computed tomography (CT) scans to minimize as much as possible complications of cervical lateral mass screw placement such as vertebral artery or nerve root injuries, facet joint violations, or inadequate placement. Methods Forty normal cervical CT scans, obtained from the emergency unit as part of the trauma workup, were included in this study plus 10 cervical cadaveric specimens obtained from the Alexandria Neuro-anatomy laboratory. There were three fixed parameters for screw insertion in this study. First, the point of screw insertion was the midpoint of the lateral mass; it was the crossing point between the sagittal and axial planes of the posterior cortex of the lateral mass. Second, the direction of the screw in the craniocaudal plane was 30 degrees cranially to avoid facet joint penetration. Third, the exit point of the screw was located on the ventral cortex of the lateral mass just lateral to the root of the transverse process in the midaxial cut of each lateral mass, to make a sound bicortical fixation without injuring the vertebral artery or the nerve root. The selected screw trajectory in this study was the line drawn between the inlet and exit points. The depth and width of the lateral mass of the cervical vertebrae from C3 to C7 were measured as well as the angle of screw trajectory from the sagittal plane. All these measures were applied on the cadaveric specimens to make sure that no injury to the vertebral artery, nerve root, or facet joint occurred. Results As regards the collected measurements of the lateral mass of all subaxial cervical vertebrae, the study revealed that the average depth of the lateral mass was 12.83 ± 1.28 mm. The average width of the lateral mass was 11.92 ± 0.96 mm. The average divergent angle of bicortical screw insertion without injury to the vertebral artery or the nerve root was 19.51 ± 1.83 degrees. As regard the cadaveric specimens, based on all the collected measurements taken from the CT scans, there was no reported injury to the vertebral arteries or nerve roots or penetration to the facet joints. Conclusion Lateral mass fixation can be applied easily and safely for all levels of subaxial cervical spine from C3 to C6 with the following parameters: (1) the point of entry is the midpoint of the lateral mass; (2) the screw trajectory is directed 30 degrees cranially and 20 degrees laterally; (3) the screw length is 13 to 15 mm.

Reconstruction of the Subaxial Cervical Spine Using Lateral Mass and Facet Screw Instrumentation

Review article. To review the indications, technical details, and complications of lateral mass and transfacet mass fixation methods. Potential advantages of rigid fixation in subaxial cervical spine have been defined as early mobilization, faster healing and fusion, and increased fusion rates. Lateral mass screw fixation has been the most popular fixation technique for posterior instrumentation. Transfacet screw fixation, on the other hand, is an alternative method less commonly used. Narrative and review of the literature. Several different techniques aiming for the most safe and secure lateral mass screw fixation have been described by several different authors. Lateral mass screws provide rigid fixation and high fusion rates in patients with healthy bone. Complications are rare when patients' anatomy is well documented and proper technique is used. Transfacet screw fixation is another method less commonly used and with better biomechanical stability. Lateral mass screw provides excellent 3-dimensional fixations from C3 to C7, and currently it is also the most commonly performed posterior fixation method.

Neurovascular complications of cervical pedicle screw fixation

We rarely use the cervical transpedicular fixation (CPF) technique in the neurosurgery departments of the authors’ institutions because the pedicle is thin and there is a risk of neurovascular damage. In this study we investigated postoperative neurovascular injury caused by the transpedicular screws of 210 pedicles in 45 patients on whom we performed CPF for various cervical pathologies. Fixation was performed between C3 and C7, and the iliac crest and lamina were used as autografts for fusion. In 205 of 210 pedicles (97.6%), the screws were in the correct position, while a non-critical lateral orientation was detected in three pedicles (1.4%). Two screws (one in each of two patients) were positioned inappropriately (0.9%, Grade 3), unilaterally and directly in the vertebral foramen, as shown on postoperative CT scans; blood circulation was normal on angiography. The fusion rate was 100%. The average screw length used for C3 to C7 was 32mm. The patients were followed up for an average of 35.7months (range: 17–60months). There was no morbidity or mortality in our study. We concluded that CPF provides very strong cervical spine fixation but also carries a risk of pedicle perforation without neurovascular injury. However, a free-hand technique performed by an experienced surgeon is acceptable for CPF for various cervical pathologies.

Postural responses without versus with acute external cervical spine fixation: a comparative study in healthy subjects and patients with acute unilateral vestibular loss

Using a diagnostic prospective cohort single center study design, the influence of a cervical collar on standing balance during dynamic postural perturbations in healthy adults and patients with acute unilateral vestibular dysfunction was measured in 31 healthy subjects and 27 patients with acute unilateral vestibular loss. The main outcome measures were completed standard protocols on the Sensory Organization Test (SOT) and Motor Control Test (MCT) of the NeuroCom Equitest(®) computerized posturography platform measured without and with acute cervical fixation, respectively. Paired t test showed no significant difference during the six conditions of neither the SOT scores nor analyzing the SOT strategies or during the MCT between the non-fixed and fixed neck in healthy subjects and in the patients (all p > 0.05). Older healthy subjects showed decreased SOT scores but equal MCT results. The age effect was more dominant in the patients when wearing the collar. Gender had no influence whether in healthy individuals nor in patients. In almost all conditions of the SOT but only in some MCT subtests patients had significantly lower scores than healthy subjects without collar and with collar (all p < 0.05). In conclusion, the SOT but only some subtest of the MCT could clearly distinguish between healthy adults and patient with acute unilateral vestibular loss. Equilibrium scores did not change significantly when the cervical spine was fixed with a collar. Acute fixation of the neck with a collar seems not to affect standing balance, even not when vestibular, visual and/or somatosensory input are also reduced.