Treatment of dens fractures with posterior atlantoaxial dislocation with transoral atlantoaxial reduction plate surgery: case report and introduction of a novel treatment option

Cervico-occipital junction infectious osteoarthritis complicated with atlantoaxial dislocation, cervical abscesses and epiduritis: A case report and review of the literature

Craniocervical junction infections are considered a rare condition and can be associated with degradation of the odontoid ligaments and, the risk of a subsequent atlantoaxial subluxation or dislocation. Osteomyelitis at this level is often seen in immunocompromised patients with, intravenous drug use or infective endocarditis. Atlantoaxial subluxation associated with pharyngeal infection or its surrounding tissues is called Grisel's syndrome. We report the case of a 29-year-old man diagnosed with infectious cervico-occipital osteoarthritis complicated by atlantoaxial dislocation, abscesses located in the retropharyngeal space, and the prevertebral space as well as upper cervical epiduritis. Our purpose is to highlight the role of radiologists in diagnosing this rare yet deadly condition.

Odontoid Fracture with Locked Posterolateral Atlantoaxial Dislocation: A Case Report and Review of Literature

CASE

Odontoid fractures with atlantoaxial dislocations are rare injuries. We report a case of a 41-year-old man with a Type 2 odontoid fracture with locket facet and posterolateral dislocation. He underwent single-stage C1-C4 posterior fixation and fusion, and at 2-year follow-up, he is symptom-free without any residual pain. Follow-up radiograph and CT scan show healed odontoid fracture with posterior fusion.

CONCLUSION

This case highlights successful management of a complex odontoid fracture by a single-stage posterior surgery. Closed reduction is usually unsuccessful, and open reduction using posterior approach is preferable.

Traumatic Posterior Atlantoaxial Dislocation With an Associated Fracture: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVE

To investigate the clinical presentation, mechanism of injury, patients' characteristics, diagnosis, treatment, and prognosis of traumatic posterior atlantoaxial dislocation with fracture (TPAD).

BACKGROUND

TPAD is an extremely rare entity, with a limited number of cases reported in the literature. Although rare, a thorough understanding of the pathogenesis and management of such cases is required due to the high risk of spinal cord compression and the severity of neurological deficits. We conducted a systematic review of all cases of TPAD with fractures reported in the literature.

METHODS

This systematic review was conducted following the Preferred Reporting Items for Systematic reviews and Meta-analysis guidelines. Relevant literature was retrieved from the Pubmed database. All published English-written studies involving human subjects with relevant data regarding TPAD were included.

RESULTS

Two case series and 20 case reports published between 1924 and 2021 describing 28 patients with TPAD were included. The median age at presentation was 51.5 years, with male predominance (83%). The most common fracture pattern was Anderson and D'alonzo type II odontoid fracture (78%). Neurological exam at presentation was intact in 52% of patients. The primary diagnostic imaging was computed tomography employed in 96% of cases. The management consisted of 2 stages protocol, initially, a temporary axial traction was employed (54%), and later definitive surgical treatment was employed (93%). The posterior surgical approach was favored in 82% of cases.

CONCLUSION

TPAD with fracture occurred in the majority of cases with Anderson and D'alonzo type II odontoid fracture, predominantly in males. Diagnosis is usually established based on computed tomography imaging; further imaging may not be indicated as it does not seem to alternate the patient's management course. Surgical intervention was employed in almost all cases, with favored results through posterior C1-C2 fusion.

LEVEL OF EVIDENCE

Level-IV.

Synthesis of modified sludge biochar for flue gas denitration: Biochar properties, synergistic efficiency and mechanism

Biochar has been recommended as a carbon material with high porosity, rich functional groups, and low cost for flue gas denitration. In this study, five different biochar materials, including original sludge biochar (SC), the KOH-impregnated biochar (SCK), the biochar of SCK washing by ultra-water (SCK-W), the H2SO4-impregnated biochar (SCS), and the biochar of SCS washing by ultra-water (SCS-W), prepared using a one-step activation method were applied to remove NO from flue gases, acting as both reductants and catalysts. The results indicate that the SCK-700 can lead to the highest NO conversion of 100% at 325 °C, and can suppress the acidic gas generation compared with SCS. The order of reduction capacity at 300-400 °C was SCK-700 > SCK-W-700 > SC-700 > SCS-700 > SCS-W-700. Furthermore, the kinetics indicated that adsorption capacity enhanced with the rise in temperature, and that SCK-700 had the largest adsorption capacity, reaching 337.15 mg/g at 400 °C.

Prediction of the functional and radiological outcome on the basis of independent factors with special emphasis on the use of 3D printed models in craniovertebral junction surgery

Background:

The aim of the study was to evaluate the advantage of performing planned surgery using customized three-dimensional (3D) printed models versus performing surgery without using 3D printed models in patients with craniovertebral junction (CVJ) anomalies and traumatic CVJ fractures and dislocations.

Methods:

Forty-two patients with CVJ anomalies, who were planned for operative intervention in the Department of Neurosurgery at SMS Hospital from March 2019 to February 2021, were randomly divided into two groups and analyzed. First group was operated after rehearsal on a customized 3D printed model whereas the second group underwent operative intervention without the rehearsal of surgery on the 3D printed model.

Results:

Forty-two patients were enrolled for the study. Twenty-five of these patients had developmental CVJ anomalies, 16 had post traumatic Atlantoaxial dislocation (AAD), and one had congenital AAD. Twenty-three patients underwent surgical intervention using 3D printed models and 19 without using 3D printed models. The outcome in the two groups was compared using modified Japanese orthopedic association score (mJOA), recovery rate, incidence of complications such as screw malposition, postoperative neurological deterioration, vertebral artery (VA) injury, and radiological improvement based on Atlanto-Dental interval, the distance of the tip of dens from Wackhenheims clivus canal line, and the distance of tip of dens from the Chamberlain’s line. The improvement in mJOA score postoperatively was found to be statistically significant in study group (P < 0.001) as compared to control group (P = 0.06). Recovery rate was better in study group than in control group (P = 0.023). In study group, the incidence of screw malposition and VA injury was lower than control group. Three patients deteriorated neurologically postoperatively in the control group and none in the study group. The average improvements in the radiological parameters were found to be better in study group as compared to control group postoperatively.

Conclusion:

The authors conclude that 3D printed models are extremely helpful in analyzing joints and VA anatomy preoperatively and are helpful in unmasking any abnormal bony and vascular anatomy effectively, making the surgeon confident about the placement of the screws intraoperatively. These 3D models help in intraoperative error minimization with better neurological outcomes in postoperative period. In our opinion, these models should be included as a basic investigation tool in patients of CVJ abnormalities. The models also offer other advantages such as preoperative simulation, teaching modules, and patient education.

Single door laminoplasty plus posterior fusion for posterior atlantoaxial dislocation with congenital malformation: A case report and review of literature

BACKGROUND

Posterior atlantoaxial dislocation (PAD) is a rare type of upper cervical spine disease. We sought to describe a unreported case of old PAD with os odontoideum (OO) and atlas hypoplasia (AH) and our unique treatment approach consisting of C1 single door laminoplasty with C1-3 posterior fixation and fusion.

CASE SUMMARY

A 70-year-old male patient who suffered from progressive aggravating numbness and limb weakness for 4 years without trauma, was diagnosed with old PAD with OO and AH. The patient underwent closed reduction and C1 single door laminoplasty with C1-3 posterior fixation and fusion instead of C1 laminectomy with occipitocervical fusion. During the 3-year follow-up, he was able to walk by himself instead of using a wheelchair and with a ± 25° range of head rotation as well as a ± 10° range of flexion-extension. Three-year follow-up images showed satisfactory reduction and fusion.

CONCLUSION

C1 single door laminoplasty with cervical fusion in PAD combined with spinal cord compression could be a suitable and effective surgical option. Compared with laminectomy and occipitocervical fusion, it retains more cervical range of motion, has a smaller incision and provides an adequate bone grafting space for atlantoaxial fusion.

Traumatic posterior Atlanto-axial dislocation: case report of an atypical C1-C2 dislocation with an anterior arch fracture of C1

Background

An atypical case of a traumatic posterior C1-C2 dislocation with an anterior arch fracture of C1 is reported. A novel conservative treatment for this rare lesion is described.

Case presentation

An eighty-nine-year-old male fell off a ladder at home and presented with an acute traumatic cervical spine trauma, which we believe involved a distraction mechanism. The patient was neurologically intact; he denied any weakness, numbness or paresthesia. A preoperative CT-scan demonstrated a posterior dislocation with an anterior arch of C1 fracture. Conservative management was elected. Reduction was achieved by closed manual reduction under general anesthesia. A postoperative CT demonstrated a complete reduction of the atlanto-axial dislocation.

Conclusion

Based on this case report and relevant literature, we present an unusual lesion of the upper cervical spine treated nonoperatively with closed manual reduction under general anesthesia. To date, there is no available consensus for the management of these lesions.

Three-Dimensional-Printed Model-Assisted Management of Craniovertebral Junction Abnormalities: An Institutional Experience with Literature Review

Study Design

Prospective study.

Purpose

To evaluate the utility and limitations of using three-dimensional (3D)-printed models for the management of craniovertebral (CV) junction abnormalities.

Overview of Literature

In comparison to other bony and vascular anomalies, CV junction abnormalities are difficult to treat. For cases of irreducible atlantoaxial dislocation (AAD), posterior reduction and stabilization have replaced anterior decompression as the standard management protocol. The use of 3D models, such as those described herein, can provide surgeons with in-depth knowledge of the vertebral artery course and bony anomalies associated with CV junction abnormalities.

Methods

Clinical and radiological features of 18 patients with CV junction abnormalities were analyzed between March 2017 and February 2019 at Sawai Man Singh Medical College, Jaipur, India. Dynamic computed tomography (CT) of the CV junction and CT angiographies of the neck with respect to the vertebral artery course at the C1–C2 joints were obtained and studied. Customized 3D models of the CV junction were then made based on the CT data, and rehearsal of the surgical procedure was performed using the 3D model one day prior to performing the actual procedure.

Results

Seventeen patients had congenital-type AAD, whereas one patient had posttraumatic AAD. Improvements in neck pain and myelopathy were seen in all patients at the follow-up, as analyzed using the Visual Analog Scale and the Japanese Orthopedic Association Scale score, respectively. There were no cases of malpositioning of screws or any direct vertebral artery injury, although in one patient, the distal flow in the dominant vertebral artery was cut off as it got compressed between the bony arch and the screw head.

Conclusions

Compared to computer-generated images, 3D-printed models are a more practical approach for dealing with complex CV junction abnormalities. They provide surgeons with deep insights into the complex bony anomalies as well as variations in the vertebral artery courses, thereby improving surgical outcomes.

Management of Unique Basilar Invagination Combined with C1 Prolapsing into the Foramen Magnum in Children: Report of 2 Cases

BACKGROUND

Basilar invagination (BI) is a developmental anomaly and commonly presents with neurologic findings. The incidence of BI associated with other osseous anomalies of the craniovertebral junction is high, including incomplete ring of C1 with spreading of the lateral masses, atlanto-occipital assimilation, hypoplasia of the atlas, basiocciput hypoplasia, and occipital condylar hypoplasia. However, BI combined with C1 prolapsing into the foramen magnum (FM) is an extremely rare condition.

CASE DESCRIPTION

A previously healthy 6-year-old girl (case 1) presented with extremities numbness and left limb weakness over a period of 3 months. Radiograph and computed tomography (CT) scan demonstrated basilar invagination with C1 and dens upward into the FM and C2-3 congenital fusion. Magnetic resonance imaging (MRI) showed ventral brainstem and medulla compression, and the medulla-cervical angle was about 100°. The patient underwent transoral anterior decompression, reduction, and fusion by transoral atlantoaxial reduction plate surgery. The symptoms of extremities numbness and limb weakness were all alleviated after surgery. Postoperative MRI showed that the medulla-cervical angle improved from 100° to 143°. An 11-year-old boy (case 2) presented with a 2-month history of limbs numbness and weakness. CT scan and MRI demonstrated BI and compression of the spinal cord, with a craniospinal angle of only 63°. The 3-dimensional (3D) printed model showed that the anterior arch and lateral of C1 was 90° flipping and vertically upward prolapsing into the FM together with the dens, and the width of the atlas was greater than the maximum diameter of the FM, which resulted in structural incarceration. The patient received posterior occipitocervical fixation and fusion surgery with hyperextension skull traction. Postoperative CT scan revealed the craniospinal angle increased to 102°.

CONCLUSIONS

We present 2 rare cases of BI combined with C1 prolapsing into the FM. We adopted different surgical strategies with satisfying outcome for these patients. We deem that the treatment of unique BI should be individualized according to the different image characteristics. The image-based modern rapid prototyping and 3D printed techniques can provide invaluable information in presurgical planning for complex craniovertebral junction anomalies.

Traumatic Atlantoaxial Lateral Subluxation With Chronic Type II Odontoid Fracture: A Case Report

Background

We report a case of an elderly patient who was diagnosed with lateral atlantoaxial subluxation with type II odontoid fracture, an extremely uncommon upper cervical spine injury that has not been previously reported in the literature to the knowledge of the authors.

Methods

An 87-year-old male reported to the emergency room following a syncopal episode after sustaining a fall. He complained of dizziness, fatigue, disruption of vision and audition, and worsening neck pain. Computed tomographic scans were positive of partial dislocation of the C1 relative to C2 and chronic fracture of dens classified as type II according to the Anderson and D'Alonzo classification system. Magnetic resonance imaging further revealed large fracture pannus tissue at the level of the dens, reducing the space in the spinal cord. There was no evidence of spinal cord injury. Atlas-axis fusion with instrumentation was performed to manage the injury. A review of the classification, occurrence, and management of upper cervical spine surgeries was performed.

Results

An acute injury to a previously unrecognized type II odontoid fracture with partial C1-C2 dislocation was identified as a rare upper cervical spine injury and classified based on the Anderson and D'Alonzo and Fielding and Hawkins classification systems. The decision was made to perform instrumented spinal fusion by inserting mass screws into C1, pars screws into C2, and locking rods to realign the vertebral bodies and address the atlantoaxial instability. Follow-up scans indicated good postsurgical reduction and fixation, including resolution of the pannus overgrowth without direct intervention.

Conclusions

Lateral atlantoaxial subluxation with chronic type II fracture of the dens constitutes a rare injury of the upper cervical vertebrae. Posterior instrumented spinal fusion was used to effectively manage the injury, leading to reabsorption of retro-odontoid pannus tissue.

REDUCTION AND INTERNAL FIXATION OF COMPLEX FRACTURES OF THE ODONTOID BY THE TRANSORAL APPROACH

ABSTRACT Type II odontoid fractures with irreducible posterior displacement are uncommon, and can cause spinal cord compression, respiratory failure and even death. Treatment is usually surgical, with transoral decompression and posterior fusion or with reduction and fusion of C1-C2 by the transoral approach. We describe a case of type II odontoid fracture with irreducible posterior atlantoaxial dislocation that was treated exclusively by the transoral approach with osteosynthesis of the odontoid, thus preserving functional segmental mobility. Level of Evidence III; therapeutic study.

An infantile alantoaxial dislocation with patent foramen ovale managed with titanium cabling and allogenic bone grafts

Atlantoaxial dislocation is a disorder that is characterized with loss of stability of the atlas and axis (C1-C2) with consequential loss of usual articulation. Although this condition is very common, no one has reported a case as young as our patients. We present a 7-month infant with bilateral paralysis of the lower limbs for four (4) months with no history of trauma. Computer tomographic (CT-scan) imaging revealed alantoaxial dislocation with severe cervical spinal cord compression. The odontoid process is displaced outwardly with no bone destruction. Doppler echocardiogram done revealed patent foramen ovale. Thorough physical examination as well as radiological evaluation revealed no feather malformations. Electrophysio - logical studies reveal normal compound muscle action potentials (CMAP) and sensory nerve action potentials (SNAPs) in all the limbs. Electromyography (EMG) also revealed normal nerves in the limbs and the trunk. We attained a stable fusion and anatomical reduction using a posterior titanium wire and an iliac bone graft harvested from his mother. This is the youngest patient reported in literature. Infantile alantoaxial dislocation should be managed at early stage to prevent long-term neurologic disorders.

Traumatic C1-2 posterolateral dislocation with dens fracture, injury of the transverse atlantal ligament, and unilateral facet fracture with subluxation of C6-7: A case report

RATIONALE

Traumatic C1-2 dislocation associated with contiguous or noncontiguous cervical spine injury is rare. Moreover, there have been no reports describing traumatic C1-2 dislocation associated with multiple contiguous and noncontiguous cervical injuries.

PATIENT CONCERNS

The authors present a case of a 20-year-old male with painful limitation of motion of the neck. This complex cervical injury occurred due to hyperextension of the head in a rotated position. The patient complained of neck pain that radiated to the left shoulder and arm, but he did not exhibit any neurological abnormalities.

DIAGNOSES

The diagnosis of the patients was traumatic C1-2 posterolateral dislocation associated with type II dens fracture (Anderson and D'Alonzo classification), type II injury of the transverse atlantal ligament (Dickman classification), and unilateral facet fracture with subluxation of C6-7.

INTERVENTIONS

The C1-2 posterolateral dislocation with type II dens fracture was successfully reduced by skull traction. The patient underwent anterior discectomy, open reduction, and fusion with plate fixation of C6-7 followed by posterior segmental fixation and fusion of C1-2.

OUTCOMES

At his postoperative 1-year follow-up, solid fusion was noted with improvement of clinical symptoms. This is the first report of traumatic C1-2 posterolateral dislocation associated with multiple C2 injuries and noncontiguous subaxial cervical injury.

LESSONS

A high index of suspicion and careful evaluation of entire cervical spine should be considered as the key to the proper diagnosis and treatment of traumatic C1-2 dislocation associated with contiguous and noncontiguous cervical injuries.

Implantation of the anterior atlantoaxial lateral mass intervertebral cage using the transoral approach

BACKGROUND

The purpose of this study was to evaluate the possibility of implanting the anterior atlantoaxial lateral mass intervertebral cage, a new type of fixation, by the transoral approach.

METHOD

This study examined the possibility of implantation in vivo by the quantitative measurement on the dry atlantoaxial bone and implantation of the anterior atlantoaxial lateral mass intervertebral cage in specimens. Anterior atlantoaxial lateral mass intervertebral cages were implanted in 10 atlantoaxial joint specimens using the transoral approach. Eight anatomical parameters (width, the thickness, ordinates, abscissas, and declination angles of the mass) from each of the 30 dry atlas and axis bone specimens were measured. These parameters determined the size and the design of the cage and the way of implantation.

RESULTS

The course of the vertebral artery forms the safe boundary for transoral surgery. The shape of the area of work exposure was an inverted trapezoid. In specimens, the anterior atlantoaxial lateral mass intervertebral cages could be successfully implanted using the transoral approach. The parameters of the human atlantoaxial lateral masses exposed anteriorly showed that there was enough space, for the safe anterior implantation of the cage. The surgery using the transoral atlantoaxial reduction and plate makes possible the implantation of the anterior cage.

CONCLUSION

The implantation of anterior atlantoaxial lateral mass intervertebral cage through transoral approach is possible.

Optimal Entry Point and Trajectory for Anterior C1 Lateral Mass Screw

STUDY DESIGN

A radiographic analysis of the anatomy of the C1 lateral mass using computed tomography (CT) scans and Mimics software.

OBJECTIVE

To define the anatomy of the C1 lateral mass and make recommendations for optimal entry point and trajectory for anterior C1 lateral mass screws.

SUMMARY OF BACKGROUND DATA

Although various posterior insertion angles and entry points for screw insertion have been proposed for posterior C1 lateral mass screws, no large series have been performed to assess the ideal entry point and optimal trajectory for anterior C1 lateral mass screw placement.

MATERIALS AND METHODS

The C1 lateral mass was evaluated using CT scans and a 3-dimensional imaging application (Mimics software). Measuring the space available for the anterior C1 lateral mass screw (SAS) at different camber angles from 0 to 30 degrees (5-degree intervals) was performed to identify the ideal camber angle of insertion. Measuring the range of sagittal angles was performed to calculate the ideal sagittal angle. Other measurements involving the height of the C1 lateral mass were also made.

RESULTS

The optimal screw entry point was found to be located on the anterior surface of the atlas 12.88 mm (±1.10 mm) lateral to the center of the anterior tubercle. This optimal entry point was found to be 6.81 mm (±0.59 mm) superior to the anterior edge of the atlas inferior articulating process. The mean ideal camber angle was 20.92 degrees laterally and the mean ideal sagittal angle was 5.80 degrees downward.

CONCLUSIONS

These measurements define the optimal entry point and trajectory for anterior C1 lateral mass screws and facilitate anterior C1 lateral mass screw placement. A thorough understanding of the local anatomy may decrease the risk of injury to the spinal cord, vertebral artery, and internal carotid artery. Delineating the anatomy in each case with preoperative 3D CT evaluation is recommended.

Atlantoaxial Joint Interlocking Following Type II Odontoid Fracture Associated with Posterolateral Atlantoaxial Dislocation: a Case Report and Review of Published Reports

A rare case of atlantoaxial lateral mass joint interlocking secondary to traumatic posterolateral C1,2 complete dislocation associated with type II odontoid fracture is herein reported and the impact of atlantoaxial joint interlocking on fracture reduction discussed. A 72-year-old man presented with traumatic atlantoaxial lateral mass joint interlocking without spinal cord signal change, the diagnosis being confirmed by radiography and 3-D reconstruction digital anatomy. Posterior internal fixation was performed after failure to achieve closed reduction by skull traction. After many surgical attempts at setting had failed because of interlocking of the lateral mass joints, reduction was achieved by compressing the posterior parts of the atlantal and axial screws. Odontoid bone union and C1,2 posterior bone graft fusion were eventually obtained by the 12-month follow-up. The patient had a complete neurological recovery with no residual neck pain or radiculopathy.

Transoral approach for revision surgery of os odontoideum with atlantoaxial dislocation

Revision surgery for os odontoideum with irreducible atlantoaxial dislocation with a transoral approach is not commonly seen. Typically, management of this type of atlantoaxial dislocation is through posterior fixation and fusion or transoral decompression and posterior fusion. This report describes revision surgery in a patient with os odontoideum who was treated with a transoral approach. A 50-year-old man was diagnosed with os odontoideum and atlantoaxial dislocation in 2007 and was treated surgically with posterior occipitocervical internal fixation and fusion. In 2012, he had recurrence of neck pain and numbness of the limbs. Neurologic function was grade D according to the standard neurologic classification of spinal cord injury from the American Spinal Injury Association. Because this was a revision surgery, the internal fixation implant was removed through a posterior approach and a transoral approach was used for release, reduction, internal fixation, and fusion. Two 6-mm cages filled with autogenous bone were introduced into the lateral mass spaces for bony fusion and distraction, and 2 cervical compressive mini-frames were used for fixation. Complete atlantoaxial reduction and decompression of the spinal cord were achieved. The patient reported improvement of symptoms after surgery. Movement of the extremities increased from grade III force to grade V, and neurologic status improved from American Spinal Injury Association grade D to grade E. A transoral approach for release, reduction, bony fusion, and fixation could be an effective procedure for the treatment of os odontoideum with irreducible atlantoaxial dislocation. It provides a new option for bony fusion and internal fixation of the atlantoaxial joint.

A review of the diagnosis and treatment of atlantoaxial dislocations

Study Design Literature review. Objective Atlantoaxial dislocation (AAD) is a rare and potentially fatal disturbance to the normal occipital-cervical anatomy that affects some populations disproportionately, which may cause permanent neurologic deficits or sagittal deformity if not treated in a timely and appropriate manner. Currently, there is a lack of consensus among surgeons on the best approach to diagnose, characterize, and treat this condition. The objective of this review is to provide a comprehensive review of the literature to identify timely and effective diagnostic techniques and treatment modalities of AAD. Methods This review examined all articles published concerning "atlantoaxial dislocation" or "atlantoaxial subluxation" on the PubMed database. We included 112 articles published between 1966 and 2014. Results Results of these studies are summarized primarily as defining AAD, the normal anatomy, etiology of dislocation, clinical presentation, diagnostic techniques, classification, and recommendations for timely treatment modalities. Conclusions The Wang Classification System provides a practical means to diagnose and treat AAD. However, future research is required to identify the most salient intervention component or combination of components that lead to the best outcomes.

Atlanto-axial dislocation complicating a type II odontoid fracture. Reduction and final fixation

A case of traumatic posterolateral C1-C2 dislocation associated with odontoid fracture is reported. This is a rare case of traumatic posterolateral C1-C2 dislocation associated with odontoid fracture. Its management is discussed. A traumatic dislocation of atlanto-axial joint associated with an odontoid fracture remains a rare injury. No case of posterior dislocation has been reported so far in the literature with this type of management. The case is of a 25 year-old-man with a primary atlanto-axial posterolateral dislocation associated with a type II displaced odontoid fracture without any neurological complication. The patient underwent gentle traction during 24 hours with a halo frame. An incomplete reduction was achieved. Two days later, a complete reduction was obtained thanks to a preoperative manual traction maintained by a Mayfield (R) modified skull clamp. Anterior C1-C2 fixation was performed according to Vaccaro's technique. The patient wore a cervical collar and underwent physiotherapy during three months. To our best knowledge, this case represents the first traumatic atlanto-axial dislocation associated with an odontoid fracture which was treated through retropaharyngeal approach. This had been rendered possible thanks to the final reduction maneuver in extension.

New clinical classification system for atlantoaxial dislocation

The purpose of this study was to define a new clinical classification of atlantoaxial dislocation based on its clinical manifestations, namely reducible atlantoaxial dislocation (RAAD), irreducible atlantoaxial dislocation (IAAD), and fixed atlantoaxial dislocation (FAAD). A total of 107 patients with atlantoaxial dislocation were respectively treated based on this clinical classification, including 66 patients with RAAD, 39 patients with IAAD, and 2 patients with FAAD. Six of the 66 patients with RAAD with rotatory atlantoaxial dislocation were treated with traction and a cervical collar, 9 with fresh type II dens fracture were treated with cannulated screw fixation, and 51 were treated with posterior atlantoaxial or occipitocervical arthrodesis. Thirty-eight patients with IAAD received a transoral atlantoaxial reduction plate system, and 1 with a giant cell tumor was treated with lesion resection and vertebral reconstruction by a shaped titanium mesh system followed by posterior occipitocervical screw-rod fixation. The 2 patients with FAAD underwent anterior decompression and received a transoral atlantoaxial reduction plate system. Follow-up data were obtained for a minimum of 6 months. All patients' neurological symptoms improved postoperatively. Bony union was accomplished by 3-month follow-up. Donor-site infection was found in 1 patient, with no occurrence of other complications. This article proposes a new classification of atlantoaxial dislocation indicating the severity and difficulty in reduction of the atlantoaxial joint. The classification system assists with decision making regarding therapeutic options. Transoral atlantoaxial reduction plate fixation and posterior atlantoaxial screw-rod fixation are commonly performed for atlantoaxial dislocation.