Posterior Atlantoaxial Dislocation Research Articles

Navigated Anterior Full-Endoscopic Transcervical Approach Odontoidectomy for Traumatic Posterior Atlantoaxial Dislocation Without Odontoid Fracture.

Complete posterior atlantoaxial dislocation (PAAD) with an unfractured odontoid process is a rare condition where a dislocated but intact odontoid process is positioned ventrally to the anterior arch of C1. This lesion is related to transverse and alar ligament rupture secondary to hyperextension and rotatory traumatic injury and is often associated with neurological deficit. The treatment strategy remains controversial, and in many cases, odontoidectomy is required. Traditional approaches for odontoidectomy (transnasal and transoral) are technically demanding and are related to several complications. This article describes a 360° reduction and stabilization technique through a navigated anterior full-endoscopic transcervical approach (nAFETA) as a novel technique for odontoidectomy and C1-C2 anterior transarticular fixation supplemented with posterior fusion. A 21-year-old man presented to the emergency room by ambulance after a motorcycle accident. On evaluation, incomplete ASIA B spinal cord injury was documented. Imaging revealed a complete PAAD. We performed a two-staged procedure, a nAFETA odontoidectomy plus C1-C2 anterior transarticular fixation followed by posterior C1-C2 wired fusion. At a 2-year follow-up, the patient had a 10-point Oswestry Disability Index score and neurological improvement to ASIA E. PAAD can be successfully treated through minimally invasive nAFETA. Noteworthy, the risks of the transoral and endonasal routes were avoided through this approach. In addition, nAFETA allows anterior transarticular fixation during the same procedure providing spinal stability. Further studies are required to expand the use of nAFETA in this field.

Novel Radiographic Parameters for Posterior Atlantoaxial Dislocation Secondary to Os Odontoideum and Its Clinical Significance

To explore correlations of 3 novel radiographic parameters with myelopathy induced by posterior atlantoaxial dislocation (PAAD) secondary to os odontoideum (OO) and assess their reproducibility. Of the 51 patients with OO with PAAD enrolled in this study, 28 developed PAAD-induced myelopathy (myelopathy group), and the other 23 patients had no myelopathy (control group). Neurologic function was evaluated by the neurologic function rating system and the Japanese Orthopaedic Association score system. Three novel radiographic parameters (OP [median sagittal diameter of the spinal canal from the posteroinferior edge of the ossicle to the anterosuperior edge of the spinous process of C2]/C4 SAC [space available for spinal cord] ratio, C1 posterior inclination angle, and posterior dislocation index) were measured by lateral cervical dynamic radiography. Their correlations with neurologic function were analyzed, and their reproducibility was assessed by the intraclass correlation coefficient (ICC). In addition, receiver operating characteristic curve analysis was performed. A significant correlation was observed between the OP/C4 SAC ratio and the neurologic function (P < 0.01), and between the C1 posterior inclination angle and the neurologic function (P < 0.01). Furthermore, their interobserver and intraobserver reliability was excellent (ICC ≥ 0.912). Receiver operating characteristic curve analysis showed that the optimal threshold value relating to myelopathy of the OP/C4 SAC ratio and C1 posterior inclination angle was 0.93 and 20°, respectively. The OP/C4 SAC ratio and the C1 posterior inclination angle seem to be 2 effective and objective radiographic parameters for relating myelopathy in patients with OO with PAAD. When the OP/C4 SAC ratio is <0.93 and/or the C1 posterior inclination angle is >20°, the risk of developing myelopathy should be highly suspected in patients with OO with PAAD.

Posterior Reduction and Intra-Articular Cage Fusion With a C2 Nerve Root Preservation Technique for Treating Posterior Atlantoaxial Dislocation Secondary to Os Odontoideum.

Posterior C1-C2 interlaminae compression fusion with iliac bone graft may lead to donor site complications and recurrent C1 posterior dislocation for posterior atlantoaxial dislocation (AAD) secondary to os odontoideum. C1-C2 intra-articular fusion often needs C2 nerve ganglion transection to facilitate exposing and manipulating the facet joint, leading to bleeding from the venous plexus and suboccipital numbness or pain. Therefore, this study was conducted to evaluate the outcomes of posterior C1-C2 intra-articular fusion with a C2 nerve root preservation technique in the treatment of posterior AAD secondary to os odontoideum. Data of the 11 patients who underwent C1-C2 posterior intra-articular fusion because of posterior AAD secondary to os odontoideum were retrospectively reviewed. Posterior reduction was performed using C1 transarch lateral mass screws and C2 pedicle screws. Intra-articular fusion was performed using a polyetheretherketone cage filled with autologous bone from the caudal edge of the C1 posterior arch and cranial edge of the C2 laminar. Outcomes were evaluated by using the Japanese Orthopaedics Association score, Neck Disability Index, and visual analog scale for neck pain. Bone fusion was evaluated by using computed tomography and 3-dimensional reconstruction. The average follow-up duration was 43.9 ± 9.5 months. All patients achieved good reduction and bone fusion, without transection of the C2 nerve roots. The mean bone fusion time was 4.3 ± 1.1 months. There was no complication related to the surgical approach and instrumentation. Function of the spinal cord manifested by the Japanese Orthopaedics Association score significantly improved ( P < .05). The Neck Disability Index score and visual analog scale for neck pain markedly decreased (all P < .05). Posterior reduction and intra-articular cage fusion with a C2 nerve root preservation technique was a promising treatment of posterior AAD secondary to os odontoideum.

The Relationship Between Cervical Sagittal Balance and Type of Atlantoaxial Dislocation Secondary to Os Odontoideum

To analyze the effect of cervical sagittal balance on the direction and type of atlantoaxial dislocation. Data of 55 patients seen at our hospital for atlantoaxial instability/dislocation caused by os odontoideum were reviewed. Radiographic variables, including T1 slope (T1S), C1-C2 angle, C2-C7 angle, C1-C2 sagittal vertical axis (SVA), C2-C7 SVA, and atlanto-dens interval (ADI), were measured preoperatively. Patients were divided into three groups according to ADI: anterior atlantoaxial dislocation, atlantoaxial instability, and posterior atlantoaxial dislocation. Differences within and between groups in radiographic variables and relationships between the investigated variables were analyzed. ADI was strongly negatively associated with C1-C2 angle (r=-0.805, P < 0.05); whereas ADI had a medium-strength positive relationship with C2-C7 angle (r= 0.425, P < 0.05) and a medium-strength negative relationship with C2-C7 SVA (r=-0.411, P<0.05). However, ADI was not significantly correlated with T1 slope (r=-0.092, P>0.05). The type and direction of atlantoaxial dislocation is closely associated with cervical sagittal balance. C2-C7 SVA is an important factor in assessing the direction of atlantoaxial subluxation secondary to os odontoideum. ADI decreases with increasing C2-C7 SVA. The larger the C2-C7 SVA, the more likely the atlantoaxial dislocation is to be posterior.

Traumatic posterior atlantoaxial dislocation without fracture of the odontoid process: illustrative case.

Traumatic posterior atlantoaxial dislocation without fracture of the odontoid process is extremely rare. Only 24 cases have been documented since the first patient was reported by Haralson and Boyd in 1969. Although various treatment strategies are reported, no consensus has been yielded. A 58-year-old man experienced loss of consciousness and breathing difficulties after being struck by a car from behind. An immediate computed tomography scan showed subarachnoid hemorrhage, a posterior atlantoaxial dislocation without C1-2 fracture, and a right tibiofibular fracture. After the patient's respiration and hemodynamics were stabilized, closed reduction was attempted. However, this strategy failed due to unbearable neck pain and quadriplegia, resulting in surgical intervention with transoral odontoidectomy and posterior occipitocervical fusion. The patient developed postoperative central nervous system infection. After anti-infective and drainage treatment, the infection was controlled. At 1-year follow-up, the patient did not complain of special discomfort and was generally in good condition. The authors report their experience with transoral odontoidectomy and concomitant posterior occipitocervical fusion in a case of posterior atlantoaxial dislocation without related fracture. Although these procedures are highly feasible and effective, particular attention should be paid to their complications, such as postoperative infection.

Can Posterior Reduction Replace Odontoidectomy as Treatment for Patients With Congenital Posterior Atlantoaxial Dislocation and Basilar Invagination?

For patients with odontoid process protrusion and basilar invagination, posterior screw-rod fixation can usually achieve satisfactory horizontal reduction, but in some cases satisfactory reduction in the vertical direction cannot be achieved at the same time. To propose a method for calculation of the theoretical maximum vertical reduction possible in individual patients. The computed tomography imaging data of patients with occipitalization and basilar invagination who were treated at our institute between January 2013 and June 2016 were retrospectively analyzed. The direction of odontoid reduction was decided by the inclination of the lateral joint. The atlanto-dental distance was assumed to be the maximum possible reduction in the horizontal direction. The maximum vertical reduction possible was calculated based on these values. A total of 82 patients (34 males and 48 females) were included. The theoretical vertical reduction value was 4.2±3.0 mm, which was significantly smaller than that of the dental protrusion (14.5±3.8 mm, P=.000). Analysis of follow-up data (29 cases) showed that, the difference between the theoretical vertical reduction value H (4.7±3.5 mm) and the actual vertical reduction value Ha (5.6±3.5 mm) was not significant (P=.139). The theoretical calculation method we proposed can well predict the actual degree of vertical reduction. The theoretical vertical reduction value is significantly lower than the odontoid protrusion value, indicating that satisfactory reduction in the vertical direction is difficult with a posterior approach alone.

Commentary: Can Posterior Reduction Replace Odontoidectomy as Treatment for Patients With Congenital Posterior Atlantoaxial Dislocation and Basilar Invagination?

Commentary: Can Posterior Reduction Replace Odontoidectomy as Treatment for Patients With Congenital Posterior Atlantoaxial Dislocation and Basilar Invagination?

Traumatic Posterior Atlantoaxial Dislocation without Related Fractures of C1 - C2 in a Patient with Traumatic Brain Injury: Case Report and Literature Review

It is exceptionally rare to have posterior atlanto axial dislocation without an associated atlas or odontoid fracture and very few cases have been reported in literature. We present a case of a 50 year old female pedestrian who was hit by car while crossing a road. She presented with a depressed level of consciousness and the Glasgow coma score of 12/15, pupils were equal and reactive to light and all limbs were moving equally. She had an extensive abrasion on the forehead which extended into scalp. CT scan showed a posterior dislocation of the atlas with respect of axis with no associated fractures of C 1 and C2. She had traumatic subarachnoid hemorrhage in the basal cisterns and multiple brainstem contusions. Closed reduction of the dislocation was done successfully under fluoroscopy guidance. MRI was done post reduction because funds were not available initially and it showed increased signal in the tectorial membrane and transverse and alar ligaments with mild cord oedema at the cervicomedullary junction. However, the patient post reduction began to deteriorate and eventually passed away before definitive treatment of her cervical-spine injury. The case is reported in view of its rarity and to review literature on this uncommon condition.

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.

Traumatic Posterior Atlantoaxial Dislocation without Fracture of the Odontoid Process: A Case Report and Literature Review

Traumatic Posterior Atlantoaxial Dislocation without Fracture of the Odontoid Process: A Case Report and Literature Review

Application of 3D printing and intraoperative navigation in surgical treatment for atlantoaxial dislocation

Objective To evaluate the clinical feasibility and effectiveness of digital orthopedic technology (3D printing and intraoperative navigation) in the surgery of posterior atlantoaxial dislocation. Methods We reviewed the clinical data of 39 cases of atlantoaxial dislocation which had been treated from June 2009 to June 2014. Eighteen patients were treated by conventional posterior atlantoaxial reduction, atlantoaxial pedicle screw fixation, and fusion surgery (conventional group), including 11 males and 7 females, aged from 34 to 71 years (mean, 52.7±12.3 years). Twenty-one patients received posterior surgery aided by 3D printing models and real-time intraoperative navigation system (3D Group), including 12 males and 9 females, aged from 30 to 71 years (mean, 51.1±11.4 years). The feasibility and clinical efficacy of digital orthopedic technology were evaluated by comparing the 2 groups in terms of operation time, blood loss, visual analogue scale (VAS) score, cervical Japanese Orthopaedic Association (JOA) score, neck disability index (NDI), and accuracy of pedicle screwing. No significant difference was found in preoperative general data between the 2 groups (P>0.05). Results The conventional and 3D groups were followed up for respectively 43.7±5.4 months and 21.3±3.2 months. There were statistically significant differences between the 2 groups in terms of operation time (100.2±9.4 minutes versus 84.8±8.2 minutes), blood loss (94.2±9.6 mL versus 85.6±8.0 mL) and accuracy of pedicle screwing [98.6% (71/72) versus 100% (84/84)] (P 0.05). There were significant differences in VAS score, JOA score, and NDI between pre-surgery and one year post-surgery (P< 0.05) in both groups. All the patients in both groups finally obtained bony fusion, with no complications like loosening, displacement and breakage of internal fixation. Conclusions Application of digital orthopedic technology (3D printing and intraoperative navigation) in the surgical treatment of reductive atlantoaxial dislocation can increase accuracy of screwing, reduce surgical risk and improve surgical safety and outcomes. This new technology is effective, feasible and worthy of spreading. Key words: Atlas; Axis; Dislocation; Computer simulation; 3D printing; Navigation template

Posterior atlantoaxial dislocation complicating odontoid fracture without neurologic deficit: a case report and review of the literature

Traumatic posterior atlantoaxial dislocation associated with odontoid fracture is extremely rare, with only eight cases reported thus far in the English literature. This report concerns a 47-year-old female who presented with considerable pain and stiffness in the neck without a neurologic deficit after injury due to a fall. Radiographs, computed tomography, and magnetic resonance imaging demonstrated a posterior dislocation of the atlas with respect to the axis with an odontoid fracture. No cord compression or intramedullary cord signal abnormalities were detected at the level of the atlantoaxial dislocation. A pedicle screw fixation/fusion was performed via a posterior approach following successful closed reduction.

A fatal iatrogenic right vertebral injury after transoral odontoidectomy and posterior cervical stabilization for a type II odontoid fracture

The authors present a singular case of an iatrogenic right vertebral artery injury, involving a 67 year-old man, who reported a type II odontoid fracture (Anderson and D'Alonzo Classification) and posterior atlantoaxial dislocation following a road traffic accident. A small injury involving the right vertebral artery occurred as a consequence of transoral odontoidectomy and posterior cervical stabilization. It was caused by bone spicules of spinal origin and their presence was confirmed by the histological section of the right vertebral artery at the level of C1–C2. The case confirms how iatrogenic vertebral artery injuries during cervical spine surgery may be potentially lethal, especially where complications arise some days after surgery.

Treatment of Dens Fractures With Posterior Atlantoaxial Dislocation With Transoral Atlantoaxial Reduction Plate Surgery

Case report. To describe a rare old dens fracture with posterior atlantoaxial dislocation that was treated with transoral atlantoaxial reduction plate surgery. Dens fractures with posterior atlantoaxial displacement are not common and cause ventral compression of the spinal cord. Management of this type of fracture is through skull traction and external fixation, posterior laminectomy and fusion, or transoral reduction and posterior fusion. A 38-year-old man sustained a car accident and was diagnosed with type II dens fractures (the classification system of Anderson and D'Alonzo) and posterior atlantoaxial dislocation. The neurological function of the patient was C grade according to the standard neurological classification of spinal cord injury from the American Spinal Association. Because of multiple trauma involving the head, lung, and the abdomen, he was treated with skull traction with about 10° of flexion. No signs of reduction were observed. The patient was treated operatively 70 days after the injury. We performed a transoral atlantoaxial reduction plate surgery using a transoral approach for release, reduction, and fixation. Finally, anterior fusion with iliac bone graft was applied. Complete atlantoaxial reduction and decompression of the spinal cord were achieved. The patient felt better after surgery. Movement of his extremities raised from grade II-III force to grade IV-V, and neurological status improved from American Spinal Association grade C to D. The treatment option achieved instant reduction, decompression, and fixation. A new treatment option for this type of injury is recommended.

Traumatic posterior atlantoaxial dislocation without associated fracture and neurological deficit

Traumatic posterior atlantoaxial dislocation without related fractures of the odontoid process and anterior arch of the atlas is exceedingly rare, with only ten published cases reported so far in English literature. We report on a 44-year-old man with post-traumatic posterior displacement of the atlas with respect to the axis without any associated fractures and neurological deficit caused by a crush injury in earthquake. Radiographs, computed tomography and magnetic resonance imaging revealed posterior displacement of the atlas with the odontoid peg lying anterior and to the right of the anterior arch of the atlas. Partial odontoidectomy and posterior fixation with bone graft were performed in one-stage procedure after several unsuccessful attempts of closed reduction. The patient did not have neurological deterioration after operation.

Posterior atlantoaxial dislocation without fracture and neurologic deficit: a case report and the review of literature

Traumatic posterior atlantoaxial dislocation without related fracture of the odontoid process is very rare, and only ten cases have been previously reported. The objective of this paper was to describe a case of traumatic posterior atlantoaxial dislocation without related fracture of the odontoid process, and its management with atlantoaxial transarticular screw fixation and bony fusion through an anterior retropharyngeal approach, and to review the relevant literature. The patient's medical and radiographic history is reviewed as well as the relevant medical literature. Posterior atlantoaxial dislocation was confirmed in a 48-year-old male struck by an automobile through conventional radiography, computed tomography and magnetic resonance imaging. No related fracture of the odontoid process or neurological deficit was found in this patient. Transarticular screw fixation of the atlantoaxial articulation through anterior retropharyngeal approach was performed after several unsuccessful attempts of closed reduction. At the latest follow-up, the lateral cervical spine radiography in flexion and extension demonstrated no instability of the atlantoaxial complex 21 months after the operation. In conclusion, patients with posterior atlantoaxial dislocation without fracture may survive with few or no-long term neurological deficit. Routine CT and MRI of the cervical spine should be carried out in patients with head or neck trauma to prevent missing of this rare clinical entity. Transarticular screw fixation of the atlantoaxial articulation through anterior retropharyngeal approach is safe and useful in case the management of dislocation is unsuccessful under closed reduction.

Posterior atlantoaxial dislocation without odontoid fracture

We report a case of posterior atlantoaxial dislocation without a fracture of the odontoid in a 35-year-old woman. There have been nine reported cases of similar injury in the English literature. The integrity of the transverse ligament following posterior atlantoaxial dislocations has not been well documented in these reports. In the present case, MRI revealed an intact transverse ligament, which probably contributed to the stability of the C1-C2 complex following closed reduction.

POSTERIOR ATLANTOAXIAL DISLOCATION WITHOUT FRACTURE OF THE ODONTOID

Uwe Neumann, MD; Horst Urbanski, MD; Klaus Riedel, MD; Department of Trauma Surgery, Heinrich-Braun Hospital, Karl-Keil Strasse 35, 08060 Zwickau, Germany

Selective paralysis of the upper extremities after odontoid fracture: acute central cord syndrome or cruciate paralysis?

A patient presented with selective paralysis of the arms after having sustained a fall. X-ray of the cervical spine showed a type II odontoid fracture with posterior atlantoaxial dislocation. The diagnosis in the emergency room was cruciate paralysis, which is frequently associated with fractures of axis and/or atlas. However, magnetic resonance imaging (MRI) of the cervical spine revealed a lesion consistent with the acute central cord syndrome (CCS) at the C2–C6 level. The patient underwent posterior atlantoaxial arthrodesis to correct instability and was discharged, without much neurological improvement. Cruciate paralysis has been reported to be associated with fractures of axis and/or atlas, and acute CCS has rarely been associated with the fractures. However, this case illustrates that the lesion responsible for selective paralysis of the upper extremities is not as specific as it had been thought to be, and that it is difficult to accurately identify the level of the cervical cord injury by neurological diagnosis and X-rays alone. Supplementary diagnostic modalities, particularly MRI, are required to make a correct diagnosis and develop a therapeutic strategy.

Posterior atlanto-axial dislocation in rheumatoid arthritis.

Seven patients with rheumatoid arthritis and posterior atlanto-axial dislocation are presented. The patients were elderly women who had suffered with the disease a long time. In all cases earlier cervical radiographs were available, excluding any predisposing congenital anomaly. Fracture and arthritic destruction of the dens, of parts of the body of the axis, or of the anterior arch of the atlas proved to be predisposing factors of the lesion.