Atlantoaxial Rotatory Dislocation Research Articles

Delayed atlantoaxial rotatory dislocation in a child with Crohn's disease: illustrative case.

Atlantoaxial rotatory dislocation (AARD) in children may be caused by neck trauma or an upper respiratory tract infection. Here the authors describe the very rare association between inflammatory bowel disease and AARD in a child. A 7-year-old girl presented with an 11-month history of torticollis that occurred spontaneously without a trauma context. Her history revealed a recent diagnosis of Crohn's disease. Physical exam of the cervical spine revealed a "cock-robin" posture. Neck radiography and three-dimensional computed tomography reconstruction established the diagnosis of AARD. Given the duration of the symptoms and failure of previous conservative treatments, the patient was taken to the operating room and underwent open reduction through posterior approach with a C1-2 fusion according to the Harms technique. The torticollis resolved with no recurrence at the last follow-up and minimal restriction of rotation. This is the third report to describe the very rare association between inflammatory bowel disease and AARD but at a very early age, the youngest in the literature. One should be aware of such association as early diagnosis may prevent aggressive surgical management.

Atlantoaxial rotatory dislocation: Surgical treatment in a pediatric patient cohort

•Surgical correction of AARD is an appropriate method of treatment after failed non-operative therapy.•The technique of surgical reduction and C1-C2 fixation using Harms/Goel technique provides excellent clinical outcomes.•In case of traumatic AARD we recommend to consider temporary fixation.

Traumatic Atlantoaxial Rotatory Dislocation in Adult: Report of 10 Cases

The AARD is related to an extreme rotation of the cervicaloccipital hinge following an accidental distraction of the spine. It often occurs in children related to ligament laxity of the cranio-spinal junction. It is rarely encountered in adults, in general, in a context of violent trauma causing a ligament injury. Only about 20 cases have been reported in the literature [1]. The particularity of this entity is its purely rotatory mechanism, which is often without an associated bone fracture. A situation that can make diagnosis difficult and require a trained physician for clinical and radiological diagnosis. The purpose of this review is to help the young orthopedics and radiologists understand this entity, become familiar with the imaging appearance in CT and discuss patient care procedures.

The Feasibility of C1-C2 Screw-rod Fixation in the Children 5 Years of Age and Younger.

Atlantoaxial fixation is technically challenging in younger children. The C1-C2 screw-rod fixation technique is established for adults but limited data about the clinical and radiographical outcome for the treatment of children with 5 years of age or younger is available. All files of children who were consecutively treated for spinal disorders were reviewed. Inclusion criteria for further evaluation were: 0 to 5 years of age at initial procedure; detailed surgical report of a posterior C1-C2 fusion with mass lateral and pedicle screw-rod fixation as described by Harms; a minimum clinical and radiographical follow-up of 24 months. The postoperative and last follow-up computed tomography scan and radiographs were used to assess the positioning and stability of the C1-C2 screw-rod construct. Eleven patients (3 boys) with a mean age of 46 months (range: 8 to 66 mo) fulfilled inclusion criteria and were evaluated retrospectively. The mean clinical and radiographical follow-up was 79 months (range: 24 mo to 170 mo). The diagnosis was atlantoaxial rotatory dislocation (4 cases), C1-C2 instability with subluxation (3 cases), atlantoaxial dislocation and os odontoideum (1 case), type II odontoid fracture (1 case), traumatic odontoid epiphysiolysis (1 case), and traumatic rupture of the transverse ligament with C1 subluxation (1 case). Intraoperatively and postoperatively no new neurovascular or vascular complication occurred. C1 lateral mass screws were placed correctly in all cases. Twenty-two C2 pedicle screws were placed correctly (85.7%), and 3 screws showed penetration of the pedicle wall (14.3%). No implant revision, implant failure, and pseudarthrosis were noted. Loss of correction was noted in 1 patient with unilateral C1-C2 fixation and a repeated dorsal fusion procedures were performed. A repeat procedure for implant removal and segmental release was performed in 3 patients to increase the axial rotation of the head. The C1-C2 screw-rod fixation is a safe technique that achieves solid fixation of the atlantoaxial complex in young children with various disorders. The technique preserves the joint and allows for segmental release via implant removal.

Concomitant atlantoaxial and atlanto-occipital rotatory dislocation in children: Radiological features, diagnostic pitfalls, and long-term outcome.

While the pathological manifestation of atlantoaxial rotatory dislocation has been well described in the medical literature, the combined dislocation of the atlantoaxial and atlanto-occipital joints, or OAARD- short for occipital-atlantoaxial rotatory dislocation- is a condition which has been poorly elucidated and probably underdiagnosed. We believe that the pathogenesis of combined atlantoaxial and atlanto-occipital dislocation is most likely a result of untreated atlantoaxial rotatory dislocation leading to chronic secondary compensation measures occurring at the occiput-C1 joints. Unique clinical and radiological features lead to difficulty in diagnosis, and conventional treatment algorithms may not apply. This paper describes a combination of clinical and radiological features which can help clinicians correctly diagnose and treat OAARD.

Letter: C2 Pedicle Screws Combined With C1 Laminar Hooks for Reducible Atlantoaxial Dislocation: An Ideal Salvage Technique for C1-C2 Pedicle Screws.

To the Editor: We read the article by Han et al1 with great interest in which the authors describe an innovative option to salvage C1-C2 fusion using laminar hooks instead of pars screws. We take this opportunity to share a similar experience and agree that it is not always possible to place screws in C1 or C2. C1-C2 fusion using C1 lateral mass and C2 pars or pedicle screws is a safe modality for the reduction and fusion of abnormal C1-C2 alignment and instability, including cases of post-traumatic C1-C2 subluxation.2-4 We managed a case of a 4-yr-old child who suffered odontoid tip fracture with rotatory atlantoaxial dislocation (Figure 1) following a fall from a height and presenting with torticollis and quadriparesis. The patient presented to us 2 wk after the fall. A 3-dimensional (3D) computed tomography (CT) reconstruction revealed a thin C2 pars and lamina. Based on CT measurements, a high chance of cortical breach of C2 while placing 3.5-mm pars or pedicle screws was anticipated during preoperative planning. Hence, that laminar screws over C2 could be an option during surgery was kept as an alternative salvaging procedure. The subluxation reduced under traction as soon as bilateral C1-C2 joints were opened and further distracted using dissectors. Then C1-C2 joint surfaces were curetted, and bone chips from iliac crest were inserted. The placement of C2 pedicle, pars, or laminar screws is considered to be more technically demanding than C1 lateral screw placement.5 Often, it is the C2 screw placement that more commonly leads to vascular or neural injury.6 This is particularly true in the case of children in which the small dimension of C2 makes it even more difficult to place screws of diameter 3.5 mm, which is the commonly available size.FIGURE 1.: Preoperative imaging of the patient showing the odontoid fracture and atlantoaxial dislocation A in the sagittal view. In the 3D CT angiogram, the right lateral mass of C1 is not visible B from the posterior view, which is seen subluxated anteriorly in the anterior view C.C1 lateral mass screws were placed according to the technique described by Goel et al.7 Because C2 dimensions were very thin for 3.5-mm screws, laminar hooks were placed bilaterally over C2 and minirods placed between C1 lateral mass screws and C2 laminar hooks. Finally, the C1 and C2 laminae were decorticated and iliac crest graft placed to achieve posterior bony fusion as well. A repeat scan at 3 mo showed good decompression of the craniovertebral junction and cord along with the implant in Situ (Figure 2). The patient's myelopathy has improved and is now mobilized independently. Therefore, in cases in which certain factors preclude the use of C2 pars/pedicle or lamina screws, C2 laminar hooks can be a useful rescue adjunct.FIGURE 2.: Postoperative CT showing a good reduction achieved with restoration of canal space in the sagittal view A. The 3D color rendering on maximum intensity projection B shows the C1 lateral mass screws and C2 laminar hooks in Situ.Funding This study did not receive any funding or financial support. Disclosures The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.

Nasoseptal flap revision in endoscopic endonasal odontoidectomy for acute atlantoaxial osteomyelitis with atlantoaxial subluxation

Vertebral osteomyelitis compromises approximately 1%–7% of all cases of osteomyelitis, whereas the cervical region is affected in 3%–10% of all cases. Not surprisingly, osteomyelitis at the craniocervical junction is a rare occurrence that poses certain challenge to surgeons. With the advancement of antibiotics, most patients with vertebral osteomyelitis can be successfully treated by conservative treatment. However, surgical intervention is indicated in cases presented with neurological deficits, spinal deformity, or instability. We present one case of retropharyngeal abscess involving the craniocervical junction that led to irreducible atlantoaxial rotatory dislocation and significant ventral cord compression. Staged procedures with endoscopic endonasal odontoidectomy assisted by nasoseptal flap reconstruction for decompression and posterior occipitocervical fusion were arranged in sequence. Nevertheless, postoperative magnetic resonance imaging revealed incomplete decompression at C2 level of the cervical spine. Prompt revision surgery with nasoseptal flap takedown and reuse performed uneventfully. The patient recovered well and was able to ambulate 5 weeks later. This case illustrated long-term radionecrosis complicated with osteomyelitis and craniocervical instability. An aggressive surgical decompression followed by staged spinal fusion would be beneficial in such complex osteomyelitis cases.

Atlantoaxial Rotatory Dislocation: Delayed Diagnose Will Result in More Invasive Treatment Options

The atlantoaxial joint represents the most mobile joint complex within the spine, secured by ligaments and capsules. Integrity of the atlantoaxial joint is crucial with respect to the mobility of the head and the upper spine. Atlantoaxial rotatory dislocation is the most common type of injury within this joint in children and is characterized by a typical position of the head (cock robin position). Nevertheless, this type of injury is frequently overlooked. The purpose of the current study was threefold. First, the characteristics of the patients with atlantoaxial dislocation were identified. Next, we checked if the time to treatment did influence the type of treatment. Finally, we checked if the age of the child at the time of treatment influenced the type of treatment. Forty-four children, who were treated consecutively due to atlantoaxial dislocation at a single spine center between September 1993 and October 2018, are analyzed retrospectively regarding age, sex, symptoms, etiology, time to diagnosis, time to treatment, and outcome. Forty-four children (30 girls, mean age 8.9 years) were included in the study. The cock robin head position was found in all of them, but neurological deficits were not found in any of them. In 21 patients, dislocation was caused by previous infection (Grisel's syndrome), whereas in 19 patients, dislocation was due to minor trauma. In 4 cases, etiology remained unknown. Mean time to sufficient treatment was 178 days. Eighteen patients received closed reduction and immobilization after 57 days at mean. Open reduction followed by temporary fixation was done in 12 patients after a mean time gap of 188 days. Bony atlantoaxial fusion was necessary in 14 children, who were diagnosed after 319 days on average. Invasiveness of treatment was dependent on the time delay between development of dislocation and treatment; a significant difference was found between invasiveness of treatment and time to treatment (Kruskal-Wallis test, p < 0,05). Moreover, older children were treated significantly more often with fusion than younger ones (χ 2, p = 0,002). Young girls are predisposed to incur an atlantoaxial rotatory dislocation, which usually occurs due to minor trauma or infection. The cock robin position is characteristic, but neurological deficits are not common. There is a need for early and sufficient treatment because delayed treatment necessitates more invasive treatment, thus leading to a complete loss of function of the most mobile joint within the spine. Finally, older children are predisposed to more invasive treatment strategies.

Neglected Traumatic Atlantoaxial Rotatory Dislocation in Adult: A Case Report.

Atlantoaxial rotatory dislocations (AARDs) are common in the pediatric population and rarely seen in adults. We describe a case of neglected AARD and subsequent management. A 25-year-old man developed a Fielding type 1 AARD following a road traffic accident. He was managed conservatively for 1.5 months before being referred to us. The patient underwent surgery 1.5 months after the accident. Closed reduction failed and C1-2 fixation with the Harms technique was performed after intraoperative reduction resulting in correction of deformity. Delay of treatment makes intraoperative reduction more difficult and increases the possibility of the chronic permanent change of neck muscles and ligaments. Hence, a high index of suspicion with a thorough clinical examination and judicious use of radiological investigations is paramount to the appropriate management of such cases.

Neglected Traumatic Atlantoaxial Rotatory Dislocation in Adult.

Atlantoaxial rotatory dislocations (AARD) are common in the pediatric population and rarely seen in adults. We describe a case of neglected AARD and subsequent management. A 25-year-old man developed a Fielding type 1 AARD following a road traffic accident. He was managed conservatively for 1.5 months before being referred to us. The patient underwent surgery 1.5 months after the accident. Closed reduction failed, and C1-2 fixation with the Harms technique was performed after intraoperative reduction, resulting in correction of deformity. Delay of treatment makes intraoperative reduction more difficult and increases the possibility of the chronic permanent change of neck muscles and ligaments. Hence, a high index of suspicion with a thorough clinical examination and judicious use of radiological investigations is paramount to the appropriate management of such cases.

Traumatic Chronic Irreducible Atlantoaxial Rotatory Fixation in Adults: Review of the Literature, With Two New Examples.

Atlantoaxial rotatory fixation (AARF) is a rare condition in adults and is almost always due to an accompanying trauma. The first example of traumatic AARF in adults was reported by Corner in 1907 and since then only 55 adult cases with this rare traumatic scenario have been published so far. Approximately 80% of adults with traumatic AARF are diagnosed soon after the traumatic events. However, in the remaining casualties, the condition might be missed with some delay from the diagnosis to treatment. If this pathology is diagnosed early enough, the conservative attempts for a closed reduction are usually effective. After closed reduction, external immobilization is required to prevent recurrence of the dislocation. However, with delayed diagnosis, the condition may remain refractory to traction on manipulation and require an open reduction instead. In the literature, such irreducible chronic AARFs are rarely reported, being confined to only 14 adult examples, in whom surgical intervention for correction of the deformity will be required. In such cases, release of the atlantoaxial facet joints is the first surgical step. In the subsequent step, reduction of the dislocated facet joints can be done via one of the already described maneuvers. As the final step, C1-C2 fixation will be necessary for prevention of re-dislocation. Herein, 2 adult patients with chronic rotatory atlantoaxial dislocation of traumatic origin are presented. In both cases, cranial traction and manipulations were ineffective and therefore an open reduction procedure was proposed and accomplished via the posterior midline corridor. The transverse rod technique was implemented subsequent to the atlantoaxial facet release. After correction of the deformity, a C1-C2 fixation was accomplished followed by arthrodesis. In addition to the outlined procedure, an historical review of the literature on this subject from the beginning of 20th century is demonstrated.

Torticollis and rotatory atlantoaxial dislocation: A clinical review.

Rotatory atlantoaxial instability can manifest as an acute episode following subtle or minor injury or even following a gentle tap on head in young children and can manifest as a painless deformity of the head. Goel technique of direct surgical opening of the atlantoaxial facet joint, manual manipulation of the facets can lead to reduction of rotatory atlantoaxial dislocation and recovery from torticollis. Torticollis can be a protective natural phenomenon in response to atlantoaxial instability and related basilar invagination. Only atlantoaxial fixation can lead to immediate postoperative reduction of torticollis. Spasmodic torticollis related to muscle hyperactivity is unrelated to atlantoaxial instability.

Long-Term Clinical and Radiologic Postoperative Outcomes After C1-C2 Pedicle Screw Techniques for Pediatric Atlantoaxial Rotatory Dislocation

Although C1-C2 pedicle screw techniques have been extensively reported in pediatric series, reports on their use have examined only small series with short follow-up periods. The aim of this study was to report pediatric patients with atlantoaxial rotatory dislocation treated with these techniques with a minimum 5-year follow-up. Retrospective review was performed of 27 pediatric patients with atlantoaxial rotatory dislocation who underwent C1-C2 pedicle screw fixation between 2004 and 2012. Clinical and radiographic outcomes were collected and compared with a control group. Follow-up period was 60-142 months (mean 84 months). Torticollis was completely corrected postoperatively in all but 1 patient. All patients experienced significant pain relief and improvement in range of motion, and 6 patients with neurologic deficits experienced significant improvement postoperatively. Both atlantodental interval and space available for the cord were significantly improved compared with preoperative values. At final follow-up, curvature was lordotic in 20 cases and straight in 7 cases. Compared with the control group, range of motion of the patient group was not significantly different in any direction except in flexion and rotation. Mean anteroposterior diameters of the spinal canal at C1 and C2 levels were not significantly different from the control group. C1-C2 pedicle screw techniques are safe and effective for treatment of atlantoaxial rotatory dislocation and result in no obvious limitation on growth in older children.

Traumatic Pediatric Atlantoaxial Rotatory Dislocation Successfully Reduced with 1 Month Total of Halter Traction: A Case Report

The occurrence of atlantoaxial rotatory subluxation is fairly uncommon; however, it is more common to be encountered in the paediatric population, typically seen after a retropharyngeal inflammation or after a minor trauma. Ligamentous laxity, shallower and more horizontally oriented facet joints especially at the C1-2 joint making them prone to have atlantoaxial subluxation or dislocation. If recognized early it can be successfully managed non-surgically before chronic inflammatory changes affect the ligaments and joint structure of the C1-2 complex. However, there is no standard treatment protocol as some authors like Nael et al and Haliasos and Norris recommended more invasive Halo skull traction. Thus, we report this case managed with less invasive Halter traction with no risk of pin site infections. We present the case of a 12-year-old Malay boy with traumatic atlantoaxial dislocation who came to us after he slipped and fell, presented with neck pain and torticollis to the left side but without other neurological deficits. A computed-tomography (CT) scan revealed an atlantoaxial rotation of 47 to the left without any signs of osseous lesions. MRI was also done and all ligaments were intact. The neck was then reduced by cautious rotation with Halter traction with the cervical spine in the neutral position with slight flexion thus avoiding harm by potential posttraumatic disc lesions. The patient was put on Halter traction for a total of one month. Post-traction revealed full range of motion of the neck without any tenderness, head and neck alignment restored to neutral position. In the children population, atlantoaxial subluxation is a rare condition but is severe if left untreated. Early treatment implies a non-surgical approach and a good outcome is observed in our case as well as reported by other authors.

The surgical treatment of the chronic atlantoaxial rotatory dislocation with C1, 2 lateral facet locked through combined anterior and posterior approach

Objective To describe the clinical manifestation of the chronic atlantoaxial rotatory dislocation (AARD) with C1, 2 lateral facets locked, and explore the effect of the operation combined with anterior retropharyngeal approach and posterior approach. Methods Data of 8 patients with chronic AARD with C1, 2 lateral facet locked who had undergone open reduction with the anterior retropharyngeal approach and C1, 2 transpedicular screw fixation with autologous iliac bone graft from Oct. 2010 to Jun. 2013 were retrospectively analyzed. There were 4 males and 4 females with an average age of 31 years old (range, 11-57 years old). The intervals from onset to diagnosis were from 29 to 180 days and the mean time was 70.6 days. 5 cases were chronic AARD with right C1, 2 lateral facets locked and 3 with left C1, 2 lateral facets locked. Reduction was failed to obtain by traction for two to four weeks. Subsequently, after open reduction with the anterior retropharyngeal approach, the patients were performed C1, 2 transpedicular screw fixation with autologous iliac bone graft for one stage or two. Results 1 patient underwent open reduction with the anterior retropharyngeal approach in stage one and C1, 2 transpedicular screw fixation in stage two because of an overall severe condition, and the other patients did anterior and posterior operation in one stage. The average operation time was 205 min (range, 160-260 min). The mean blood loss was 210 ml (range, 100-300 ml). There were no operation complications except one young girl reflected pain in autologous iliac donated area, and pain relieved when taking nonsteroidal antiinflammatory by oral for one week. All patients had been followed up for a mean period of 14.8 months (range, 5-37 months). Three-dimensional computed tomography revealed C1, 2 arthrodesis bone graft fusion from two to four months and the average was 3.1 months. Neither recurrence of symptoms nor dislocation was observed at the latest follow-up. Conclusion Open reduction through the anterior retropharyngeal approach with C1, 2 transpedicular screw fixation is an effective treatment strategy for chronical AARD with C1, 2 lateralfacets locked, which reduces surgical complications with less operation difficulty. Key words: Cervical atlas; Axis; Atlanto-axial joint; Dislocations

Closed manual reduction maneuver of atlantoaxial rotatory dislocation in pediatric age

The purposes of this study were to characterize the clinical and radiological features of type 1 and type 2 atlantoaxial rotatory dislocations (AARD) and to evaluate the outcome of the manual reduction maneuver for these types of dislocations in pediatric patients. This study considered 12 pediatric patients with AARD who were treated between January 2003 and March 2013. The diagnosis was established by clinical findings and 3D-CT. All of the patients were treated by closed manual reduction and then a cervical orthosis was performed. All of the patients were followed up at regular intervals. The causes of the AARD were trauma (91.67 %) and infection (8.33 %). The time between onset of symptoms and admission to the hospital ranged from 16 days to 6 months. In radiological evaluation, the mean rotational angulation of the patients was 30.58°. The 3D-CT examination showed that six patients (50 %) had type 1 dislocation and six patients (50 %) had type 2 dislocation. All of the patients were treated by closed manual reduction and then a cervical orthosis was performed. For 11 patients (91.67 %), dislocation was successfully reducted and maintained. One patient (8.33 %) underwent surgery, following recurrence of the second closed reduction maneuver. This preceding treatment method has successfully produced a fast and recurrence-free alignment on all except one of our patients. This technique can be a useful treatment alternative in carefully selected AARD cases. Future research is encouraged to improve decision making in the application of this treatment method and provide additional validation of the current findings.

Is the Fielding Classification System Enough for Managing Atlantoaxial Rotatory Dislocation?

Objective: To assess the Fielding classification system for management of atlantoaxial rotatory dislocation (AARD). Summary of Background Data: AARD is a rare condition that occurs more commonly in children than in adults. The classification system proposed by Fielding in 1977 is most frequently used for AARD, and this classification system was devised in the days before the advent of computed tomography. Methods: We discuss the efficacy of the Fielding classification system in this rare but significant disorder. Conclusions: The Fielding classification system should be modified on the basis of radiologic results to prevent some cases from being classified mistakenly as the more serious type and treated through nonoperative intervention.

Unilateral axis facet hypertrophy—a rare case of irreducible rotatory atlantoaxial dislocation and a review of the literature

Fixed atlantoaxial dislocations are difficult to treat and there is no consensus in the treatment protocol. Unilateral enlargement of the atlas-axis facet complex in fixed atlantoaxial dislocations is a very rare condition. These pathologies are usually quite unstable and surgical treatment is necessary in unreductable cases. A 52-year-old woman with a diagnosis of irreducible-fixed rotatory atlantoaxial dislocation presented with acute onset of dizziness, loss of balance, and tetraparesis. She was under 8 years of conservative follow-up. Review of radiology revealed unilateral C2 superior facet hypertrophy compressing the medulla and obstructing the vertebral artery. To treat this condition, we have used a posterior midline approach and removed the lateral portions of the posterior rim of the foramen magnum and the assimilated posterior arch of C1. The V3 segments of the vertebral arteries were exposed bilaterally. The atlantoaxial joint complex on the left was hypertrophied compressing V3. We have removed hypertrophied lateral mass of the atlas and the hypertrophic superior articular facet of C2 for decompression. Patency of both vertebral arteries were checked intraoperatively by Doppler and indocyanine green angiography. We have fixated craniocervical junction on the same session. Patient was neurologically intact and she had confirmed fusion on the surgical site after three years of follow-up. This is a rare case of unilateral hypertrophy of the C2 superior articular facet in a fixed atlantoaxial rotatory dislocation. Progressive compression of medulla and the left vertebral artery leaded to clinical worsening of neurology in this case after 8 years of follow-up. Surgical treatment was necessary for neurological decompression and to establish stability.

Successful Conservative Treatment for Neglected Rotatory Atlantoaxial Dislocation

Rotatory atlantoaxial subluxation (RAS) is a rare condition that is often misdiagnosed and therefore incorrectly managed. We describe our experience and propose an algorithm for treating neglected RAS nonoperatively. All consecutive children with neglected (>6 wk) RAS were treated in our department between 2005 and 2010 by cervical traction using a Gleason traction device and nonsteroidal anti-inflammatory drugs and muscle relaxants. When reduction was not achieved, the Gleason device was replaced by a halo device without manipulative reduction, and weight was added as necessary until reduction was successful. Fixation of reduction was either by a sternooccipital mandibular immobilizer or a halo vest for 3 to 4 months. All 5 children (4 boys and 1 girl, aged 4 to 11 y) were successfully treated for neglected RAS. The mean duration from symptom onset (eg, limited neck range of motion, discomfort) to treatment initiation was 11.6 weeks (range, 6 to 16 wk). Closed reduction was achieved by a Gleason or a noninvasive halo device within 1 to 2 weeks in 4 cases. The fifth case was reduced after 5 weeks of traction using a halo with a 5 kg weight. All children had symmetrical full range of motion, normal neurological examination, and were fully engaged in educational and sports activities without recurrent dislocations at final follow-up (mean, 30 mo; range, 18 to 49 mo). Conservative treatment by gradual and prolonged traction without manipulative reduction in neglected RAS might be a successful method. Reduction can often be achieved within 2 weeks of treatment onset. Level IV (retrospective case series).

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.