Traumatic Atlantoaxial Instability Research Articles

A Case of Suspected Traumatic Atlantoaxial Instability in a Cat with Favorable Progress on Medical Treatment

3カ月齢の雄のラグドールが突然の四肢の起立困難を主訴に主治医を受診し，翌日に紹介来院した．麻酔下のX線検査では異常所見が認められなかったが，MRI検査にて環軸椎背側領域の脊髄実質における信号強度異常，脳脊髄液検査にて出血を示唆する所見が認められたことから，外傷性環軸椎不安定症が疑われた．頸部の外固定，運動制限，投薬，理学療法といった内科的治療により，経過は良好であった．経時的なMRI検査にて損傷の疑われた脊髄実質における病変部位が空洞化していたことから，神経症状の将来的な残存が示唆された．猫の環軸椎不安定症に対して継時的なMRI検査によって脊髄実質の評価を行うことは，予後判断に有用であると考えられた．

The application of C2 transpedicular screw, C1 laminar hook fixation and bone graft in the atlantoaxial instability

Traumatic atlantoaxial instability usually results from a motor vehicle accident, falls and motorcycle accidents. Atlantoaxial instability can lead to spinal cord compression and neck pain, but, spasticity and radicular symptoms as well. The purpose of surgery is to remove the compression and stabilize the joint permanently. To date, several surgical techniques have been described to remedy C1-C2 instability. In this study, the clinical and radiological outcomes of patients who operated with the C1 (Atlas bone) laminar hooks fixation and bilateral C2 (Axis bone) trans-pedicular screw technique were shown. Also, the advantages and disadvantages of this technique are discussed. From March 2010 to December 2017, 12 patients who have atlantoaxial instability were surgically treated by modified fixation technique which consists C1 laminar hooks fixation and bilateral C2 transpedicular screw. Twelve patients were operated with this procedure from March 2010 to December 2017. All the patients were checked with flexion-extension x-rays at the end of the twelfth week. The posterior bony fusion formation was observed on imaging in all patients. C2 bilateral pedicle screw combined with C1 laminar hook system is a good method for atlantoaxial instability in the conditions which is not convenient for insertion of C1 lateral mass and C2 trans-articular screw. However, this method may not be available in some cases such as traumatic, infection, neoplastic or degenerative pathologies in which the posterior arch of the atlas is damaged.

A Comparison of the Long-Term Results of Posterior Transarticular Stand-Alone Screw Instrumentation and Magerl Technique in Patients with Traumatic Atlantoaxial Instability: Mean 5-Year Follow-Up Study with Radiological and Patient-Rated Outcomes Assessments

To perform a radiological analysis of the degeneration of C1-C2 joints after C1-C2 transarticular fixation (TAF) and compare the long-term results of a routine Magerl technique (RMT) to a posterior transarticular C1-C2 stand-alone screw instrumentation (SAS) application. A total of 40 patients (26 men and 14 women) were included in the present retrospective observational cohort study. The mean follow-up period was 61.7 months (range, 11-118). The mean patient age at the baseline examination was 48.4 years (range, 22-82). Of the 40 patients, 11 were included in the RMT group and 29 in the SAS group. The structure of 80 atlantoaxial joints was analyzed, with grade 4 degenerative changes observed in 57 joints (71.3%). Of the 40 analyzed atlanto-odontoid joints, grade 4 degenerative changes were revealed in 18 joints (45%). C1-C2 bone fusion was observed in 38 patients (95%) and stable fibrous fusion in 2 patients (5%). No cases of C1-C2 nonunion were revealed. No statistically significant differences in the frequency of C1-C2 fracture consolidation or C1-C2 fusion were revealed between the RMT and SAS groups. The application of cortical lag screws in TAF might result in stable atlantoaxial joint fusion formation without joint curettage. Atlanto-odontoid joint fusion was also observed after C1-C2 TAF. The application of cortical lag screws for bilateral fixation using the SAS technique resulted in C1-C2 fusion in 93.1% of cases, comparable to the results with the Magerl technique.

Outcomes of surgery for unstable odontoid fractures combined with instability of adjacent segments.

BackgroundAt present, traumatic atlantoaxial dislocation or C2-3 instability complicating odontoid fractures remains rarely reported. The aim of this study was to further investigate the surgical treatment strategies and curative effects for odontoid fractures combined with instability of adjacent segments.MethodsThis is a retrospective study of 12 patients (5 females and 7 males; age, 21–65 years) who underwent internal fixation for odontoid fractures (type II and shallow type III) and atlantoaxial instability in 6 cases, C2-3 instability in 4 cases, simultaneous C1-2 and C2-3 instability in 2 cases between January 2005 and June 2012. Accordingly, individualized surgeries were performed. Fracture healing and bone fusion were determined on X-ray scan. Upper limbs, lower limbs and sphincter functions were assessed using the Japanese Orthopaedic Association (JOA) score. Frankel grading system was used for the evaluation of neurological situation.ResultsMean follow-up time of all 12 cases was 16.4 months (range, 12 to 48 months). Odontoid fracture healing was obtained in all patients within 9 months, and graft fusion was achieved within 6 months. JOA score was significantly improved from 6.3 ± 3.1 preoperatively to 11.1 ± 4.6 at 12 months after operation (P = 0.007), with 50.5 ± 25.7% recovery rate and 66.7% excellent and good rate. Except one patient still had Frankel grade B neurological injury at 12 months after surgery, the other patients improved their neurological situation (at 1 grade in Frankel scale). One patient developed wound fat liquefaction which resolved by changing the dressing. Cerebrospinal fluid leakage occurred in three patients, which resolved after the continuous drainage for 2 days.ConclusionsAccording to the characteristics of odontoid fractures, the individualized operative procedure should be performed, resulting in high fracture healing rate, function recovery rate, and less, transient complications.

Clinical study on anterior hollow screw fixation in the treatment of traumatic atlantoaxial instability odontoid fractures

Objective To study the effect of anterior hollow screw fixation in the treatment of traumatic atlantoaxial instability odontoid fractures .Methods 25 patients with traumatic atlantoaxial instability odontoid frac-tures who received anterior hollow screw fixation were chosen .The neck was fixed for 3 months after operation .The fracture reduction ,fixation and fracture healing ,the elimination of the head and neck clinical symptoms and postopera-tive complications were examined and compared before and after surgery .Results All 25 patients were followed up for 6 to 24 months,an average of 15 months.Odontoid fractures healed without implant loosening ,fracture,wound in-fections and other complications .6 cases of muscle weakness and numbness recovered after 3 to 4 months.Conclusion The current treatment of odontoid fractures in many ways ,but the anterior compression screw fixation in the treatment of odontoid fractures has advantages of simple operation ,reliable fixation,high healing rate,etc.,it is the first choice for this type of fracture . Key words: Anterior; Odontoid fractures; Traumatic

The Use of Lateral Mass C1 and Pedicle C2 Screw for Fixation of Post Traumatic Upper cervical Instability: Surgical Technique and Operative Outcome

Background Data: The atlantoaxial segment of the cervical spine is a complex anatomic and functional structure. There are many diseases that can affect this segment and lead to instability as trauma, degenerative, inflammatory,neoplastic, or congenital diseases. It requires fusion for adequate immobilization and stabilization. Many surgical methods used for treatment of C1-C2 instability as posterior wiring techniques, C1–2 transarticular screws and lastly, C-1 lateralmass and C-2 pedicle screws fixation which has more advantages than other methods of C1–2 fixation.Study Design: Retrospective clinical case review. Purpose: The aim of this work is to evaluate the surgical technique and early outcome of C1 lateral mass and C2 pedicle screw fixation in post traumatic atlantoaxial instability.Patients and Methods: The study was conducted on 12 patients admitted in the emergency department of the main Alexandria university hospital presented with post traumatic atlantoaxial instability started from January 2010 till January2012. We did C1 lateral mass and C2 pedicle screws fixation using polyaxial screw system and rods. Ten patients (83.3%) were males and 2 females (16.7%) with age ranged from 21 to 48 years. Neck pain was the most common presentationin all the 12 patients (100%) followed by myelopathy in 6 patients (50%) and only 2 patients (16.7%) presented with sphincteric disturbance. Results: The average time for surgery was 135min. Blood loss ranged from 250 to900 ml with mean of 400ml. Dural tear occurred in only one patient (8.3%), with mild CSF leak postoperatively that stopped spontaneously. No vertebral artery injury was reported during surgery. The average hospital stay of the patientsranged from 2-10 days with a mean of 4 days. A total of 48 poly axial screws were inserted. We found that 40 screws (83.4%) were optimal in position, 8 screws (16.6%) were suboptimal including, 3 (6.2%) were medially directed, 2 (4.2%) were laterally directed, 2 (4.2%) were too long and only one screw (2%) was misplaced that needed to be reoperated for redirection. Neck pain improved in all the patients (100%) postoperatively, myelopathy improved in 5 patients (41.6%), and sphincteric disturbance improved in one patient (8.3%). Good fusion was achieved in 11 patients (91.7%) within 6 months. Conclusion: Lateral mass C1 and pedicle screw C2 fixation offer an alternative means of achieving atlantoaxial fusion. The technique is safer with less complication. Laminectomy or fracture of the posterior elements does not prevent the use of this fixation procedure. (2012ESJ019)

Minimally invasive anterior transarticular screw fixation and microendoscopic bone graft for atlantoaxial instability

Even though transarticular screw (TAS) fixation has been commonly used for posterior C1-C2 arthrodesis in both traumatic and non-traumatic lesions, anterior TAS fixation C1-2 is a less invasive technique as compared with posterior TAS which produces significant soft tissue injury, and there were few reports on percutaneous anterior TAS fixation and microendoscopic bone graft for atlantoaxial instability. The goals of our study were to describe and evaluate a new technique for anterior TAS fixation of the atlantoaxial joints for traumatic atlantoaxial instability by analyzing radiographic and clinical outcomes. This was a retrospective study of seven consecutive patients with C1-C2 instability due to upper cervical injury treated by a minimally invasive procedure from May 2007 to August 2009. Bilateral anterior TAS were inserted by the percutaneous approach under Iso-C3D fluoroscopic control. The atlantoaxial joint space was prepared for morselized autogenous bone graft under microendoscopy. The data for analysis included time after the injuries, operating time, intraoperative blood loss, X-ray exposure time, clinical results, and complications. Radiographic evaluation included the assessment of atlantoaxial fusion rate and placement of TAS. Bone fusion of the atlantoaxial joints was assessed by flexion extension lateral radiographs and 1-mm thin-slice computed tomography images as radiographic results. Clinical assessment was done by analyzing the recovery state of clinical presentation from the preoperative period to the last follow-up and by evaluating complications. A total of 14 screws were placed correctly. The atlantoaxial solid fusion without screw failure was confirmed by CT scan in seven cases after a mean follow-up of 27.5 months (range 18-45 months). All patients with associated clinical presentation made a recovery without neurologic sequelae. Postoperative dysphagia occurred and disappeared in two cases within 5 days after surgery. There were no other complications during the follow-up period. Percutaneous anterior TAS fixation and microendoscopic bone graft could be an option for achieving C1-C2 stabilization with several potential advantages such as less tissue trauma and better accuracy. Bilateral TAS fixation and morselized autograft affords effective fixation and solid fusion by a minimally invasive approach.

Traumatic atlantoaxial rotatory subluxation (TAARS) in adults: A report of two cases and literature review

Pure traumatic atlantoaxial rotatory instability is a rare entity in adults. A review of the English literature revealed 10 cases of bilateral, and two cases of unilateral traumatic atlantoaxial rotatory dislocation (TAARD) in adults since the first report in 1969 (Table 1). The terminology associated with traumatic rotatory injuries at the atlantoaxial level is somewhat confusing, and a clear distinction should be made between rotatory subluxation and rotatory dislocation, as the mechanics of injury and the optimum management may differ. In this report, we use the term atlantoaxial rotatory subluxation to define a partial and transient reducible displacement of the adjacent articular surfaces at this level. Our purpose is to describe two cases of traumatic atantoaxial rotatory subluxation (TAARS), focussing on management, outcome and a review of the literature.

Management of traumatic atlanto-axial instability: A retrospective study of eight cases

Background:C1 lateral mass–C2 transpedicular fixation is an accepted surgical procedure of choice in a large number of cases with traumatic atlanto-axial instability. However, bony and vascular anomalies can predispose to unacceptably high risk with this procedure, And hence are the contraindications for this procedure. The purpose of this study is to analyze the clinical and radiological results in such cases for which only unilateral fixation has been performed in cases where bilateral fixation could not be performed due to various reasons.Materials and Methods:Eight patients (7 males, 1 female) with a mean age of 41.12 years (range 12-68 years), who presented with traumatic atlanto-axial instability and in whom bilateral fixation could not be performed, were treated with unilateral C1 lateral mass–C2 transpedicular fixation. Of these cases, preoperative vertebral artery occlusion was noted in one case, iatrogenic vertebral artery injury in two cases and bony anomalies or fractures in the remaining of five cases. All patients were evaluated clinically with the American Spinal Injury Association (ASIA) scale and radiologically with computed tomography scans and serial X-ray using criteria to evaluate stability.Results:All cases were evaluated at 6 months followup with mean followup of 2 years and one month (range 6 months to 4 years). All eight patients showed adequate stability and fusion at 6 months; clinically there was no significant restriction of neck movement in any of the patient. There was no neurological deterioration in any of the patient at their last follow-up.Conclusion:Unilateral C1 lateral mass–C2 transpedicular fixation could be considered a viable option in cases of traumatic atlanto-axial instability where vascular and osseous anomalies contradict a bilateral fixation.

One stage anterior-posterior approach for traumatic at-lantoaxial instability combined with subaxial cervical spinal cord injury

Objectives To explore the clinical features of traumatic atlantoaxial instability combined with subaxial cervical spinal cord injury (CSCI), and to analyze the feasibility, indication and therapeutic effects of anterior-posterior approach in such cases. Methods From March 2004 to September 2009, 16 cases with this trauma were admitted and surgically treated in our department. Before surgery, skull traction was performed. Posterior atlantoaxial pedicle screw internal fixation and bone graft fusion were conducted to manage traumatic atlantoaxial instability. As for subaxial CSCI, anterior cervical corpectomy or discectomy decompression, bone grafting and internal fixation with steel plates were applied. Results All operations were successful. The average operation time was 3 hours and operative blood loss 400 ml. Satisfactory reduction of both the upper and lower cervical spine and complete decompression were achieved. All patients were followed up for 12 to 36 months. Their clinical symptoms were improved by various levels. The Japanese Orthopaedic Association (JOA) scores ranged from 10 to 16 one year postoperatively, 13.95±2.06 on average (improvement rate=70.10%). X-rays, spiral CT and MRI confirmed normal cervical alignments, complete decompression and fine implants' position. There was no breakage or loosening of screws, nor exodus of titanium mesh or implanted bone blocks. The grafted bone achieved fusion 3-6 months postoperatively and no atlantoaxial instability was observed. Conclusions Traumatic atlantoaxial instability may combine with subaxial CSCI, misdiagnosis of which should be especially alerted and avoided. For severe cases, one stage anterior-posterior approach to decompress the upper and lower cervical spine, together with reposition, bone grafting and fusion, as well as internal fixation can immediately restore the normal alignments and stability of the cervical spine and effectively improve the spinal nervous function, thus being an ideal approach.

A three-dimensional study of the atlantodental interval in a normal Chinese population using reformatted computed tomography

The atlantodental interval has been usually used for the evaluation of atlantoaxial instability. However, the asymmetry of the lateral atlantodental interval is occasionally found in healthy individuals. Controversy therefore exists as to the clinical significance of this asymmetry in patients after trauma. The purpose of this study was to determine the normal range of atlantodental intervals in normal individuals using reformatted computed tomography. In this study, C1-C2 vertebrae were imaged in 230 adult patients by a Lightspeed Vct CT (General Electric, CT, USA) with a slice thickness of 0.625 mm. After reformatting the original images, the anterior atlantodental interval (AADI) and lateral atlantodental interval (LADI) were measured. The AADI was found to be 1.83 ± 0.46 mm (0.9-3.4 mm) in males and 1.63 ± 0.43 mm (0.5-3.2 mm) in females. The AADI was significantly greater in males than in females (p < 0.05). The 95% confidence interval for AADI was 1.75-1.90 mm in males and 1.54-1.72 mm in females. No statistically significant differences were found between males and females in the left and right LADI, and LADI asymmetry. The left LADI was found to be 3.38 ± 0.87 mm (1.7-6.0 mm), and the right LADI was 3.42 ± 0.84 mm (1.7-5.9 mm) in males, while the left LADI was 3.30 ± 0.73 mm (1.5-5.3 mm) and the right LADI was 3.37 ± 0.92 mm (1.7-5.9 mm) in females. The 95% confidence interval for left LADI was 3.23-3.52 and 2.94-3.25 mm, and for right LADI was 3.27-3.56 and 3.18-3.56 mm in males and females, respectively. The mean asymmetry of LADI was 0.76 ± 0.66 mm (0.0-3.5 mm) in males and 0.73 ± 0.70 mm (0.0-3.7 mm) in females. The 95% confidence interval for LADI asymmetry was 0.65-0.87 mm in males and 0.59-0.88 mm in females. Most of the population was found to have an asymmetry ranging between 0.1 and 2.0 mm. The current study shows that LADI asymmetry is common in patients without any cervical spine abnormalities. LADI asymmetry may be a normal anatomic variant and there is no evidence to confirm that LADI asymmetry is a sensitive or specific indicator of traumatic atlantoaxial instability. Radiologists and clinicians should be aware of this normal range of asymmetry when interpreting CT scans of the atlantoaxial region.

Clinical evaluation of three types of combined posterior atlantoaxial internal fixation techniques for treatment of atlantoaxial instability

Objective To assess clinical curative effect of three types of combined posterior atlantoaxial internal fixation techniques in treatment of atlantoaxial instability. Methods The study involved 68 patients with atlantoaxial instability treated with different fixation techniques from August 2002 to March 2008. ( 1 ) Transpedicular fixation was performed in 32 patients including 20 patients with Anderson Ⅱ odontoid fractures (seven with old odontoid fracture and 13 with fresh fractures), six with type Anderson Ⅲ fresh odontoid fractures, four with disrupt of transverse ligament of the atlas and two with congenital loose odontoid process combined with atlantoaxial instability. (2) Transpedicular internal fixation with screws of atlas incorporating C2 laminar screws was performed in 20 patients with upper cervical injury including eight with type Ⅱ odontoid process fractures combined with atlantoaxial backward dislocation,four with type Ⅱ odontoid process fractures combined with atlantoaxial forward dislocation, two with nonunion of odontoid process fractures, three with type Ⅲ odontoid process fractures combined with atlantoaxial unsteadiness and three with atlantoaxial dislocation combined with disrupt of transverse ligament of atlas. (3)A total of 16 patients with traumatic atlantoaxial instability, reducible atlantoaxial dislocation and irreducible atlantoaxial dislocation were treated with four-point internal fixation technique using autologous iliac bone grafts. Results (1) A total of 120 screws were implanted in 32 patients, with no spinal cord or vertebral artery injury after surgery. Atlas lateral mass fixation was adopted in three patients because of broken posterior arch of the atlas. Postoperative CT showed that two screws were inserted into the vertebral artery hole and that one screw was inserted medially into the spinal canal and caused medial correx rupture, but both with no clinical symptoms. All 32 patients were followed up for 6-42 months ( average 26 months), which showed solid fusion in all patients. The postoperative JOA scores ranged from 13.2 points to 16.8 points (average 14. 8 points). (2) Thirty-two screws were implanted in 20 patients,with no spinal cord or vertebral artery injury. The patients were followed up for mean six months ( range 6-14 months). Postoperative X-ray showed sound bone fusion, with no cervical instability, loosening or breakage of the screws. (3) The symptoms of all the patients were improved at different degrees, with no neurological deterioration or severe complications, such as nerve blood vessel injury. All 16 patients were followed up for 8-26 months ( average 16 months), which showed bony fusion in all patients at 3-6 months after surgery. The spinal cord function was improved markedly in five patients, good in eight, mild in two but unchanged in one. Conclusions Three types of combined posterior atlantoaxial internal fixation techniques have advantages of rigid, short-segmental and three-dimensional fixation and hence are effective methods for treatment of upper cervical injuries. The combination mode can be varied according to specific condition of the patients. Key words: Atlanto-axial joint; Joint instability; Internal fixation; Spinal fusion

Use of the Kishigami Atlantoaxial Tension Band in Eight Toy Breed Dogs with Atlantoaxial Subluxation

To determine the applicability, complications, and long-term functional outcome of the Kishigami Atlantoaxial Tension Band (Kishigami AATB) for management of congenital and traumatic atlantoaxial (AA) instability in toy breed dogs. STUDY DESIGN; Case series. Toy breed dogs (n=8) with congenital or traumatic AA instability. The AA joint of each dog was surgically stabilized through a dorsal approach using the original or a modified version of the Kishigami AATB. Pre- and postoperative neurologic status, radiographs, and complications were reviewed. Follow-up examination was performed at 1 and 12 months. Functional improvement occurred in 5 dogs; 1 dog did not improve or worsen and 2 dogs were euthanatized at owner request. Adequate reduction and stabilization was achieved in 7 dogs based on immediate postoperative radiographs; failure of reduction was evident in 1 dog. No relevant complications occurred. Kishigami AATB may be acceptable as an alternative method for dorsal stabilization of AA subluxation in toy breed dogs in which use of ventral screws or pins is challenging. Experience with this technique in a larger population is necessary to compare our results to those reported by ventral approach. CLINICAL RELEVANCE; The surgical technique described is effective, safe, and simple in the surgical treatment of AA subluxation in toy breed dogs.

Troublesome Occipital Neuralgia Developed by C1-C2 Harms Construct

Recently, Harms and Melcher modified Goel's approach, the C1 lateral mass and C2 pedicle screw fixation, and the new technique is currently in favor among neurosurgeons. Comparing to the advantages of Harms construct, the disadvantages were not extensively investigated. We experienced a patient with severe occipital pain developed after the C1 lateral mass screw placement for the traumatic atlantoaxial instability. We reviewed literatures about Harms construct with focus on the occipital neuralgia as a postoperative complication and suggest here technical tips to avoid the troublesome pain.

Magerl's technique for patients with traumatic atlantoaxial dislocation and instability

创伤性寰枢椎骨折脱位易造成寰枢椎失稳,并可导致高位颈髓慢性压迫,逐渐出现不同的临床症状,严重者甚至危及生命,多数患者需采取手术治疗以恢复寰枢椎稳定性.C1-2经关节螺钉技术(Magerl技术)由于其显著的生物力学优势及更好的术后骨性融合率而成为治疗的首选.我科自2003年5月～2005年11月,采用Magerl技术治疗创伤性寰枢椎脱位失稳患者13例,均取得良好疗效

Atlantoaxial stabilization with the use of C1–3 lateral mass screw fixation

Atlantoaxial stabilization has evolved from simple posterior wiring to transarticular screw fixation. In some patients, however, the course of the vertebral artery (VA) through the axis varies, and therefore transarticular screw placement is not always feasible. For these patients, the authors have developed a novel method of atlantoaxial stabilization that does not require axial screws. In this paper, they describe the use of this technique in the first 10 cases. Ten consecutive patients underwent the combined C1-3 lateral mass-sublaminar axis cable fixation technique. The mean age of the patients was 62.6 years (range 23-84 years). There were six men and four women. Eight patients were treated after traumatic atlantoaxial instability developed (four had remote trauma and previous nonunion), whereas in the other two atlantoaxial instability was caused by arthritic degeneration. All had VA anatomy unsuitable to traditional transarticular screw fixation. There were no intraoperative complications in any of the patients. Postoperative computed tomography studies demonstrated excellent screw positioning in each patient. Nine patients were treated postoperatively with the aid of a rigid cervical orthosis. The remaining patient was treated using a halo fixation device. One patient died of respiratory failure 2 months after surgery. Follow-up data (mean follow-up duration 13.1 months) were available for seven of the remaining nine patients and demonstrated a stable construct with fusion in each patient. The authors present an effective alternative method in which C1-3 lateral mass screw fixation is used to treat patients with unfavorable anatomy for atlantoaxial transarticular screw fixation. In this series of 10 patients, the method was a safe and effective way to provide stabilization in these anatomically difficult patients.

Application of ventral pins and polymethylmethacrylate for the management of atlantoaxial instability: results in nine dogs.

The purpose of this report was to determine the efficacy of the application of ventral pins and polymethylmethacrylate for the management of congenital and traumatic atlantoaxial instability (AAI) in dogs. Medical records and radiographs of nine dogs with AAI were reviewed for neurological deficits, clinical diagnosis, surgical technique, and long-term outcome. Six toy breed dogs with congenital AAI and three medium or large breed dogs with traumatic AAI were identified for inclusion in the study. The atlantoaxial joints of nine dogs with AAI were surgically stabilized using ventral application of pins and polymethylmethacrylate. Follow-up evaluation for resolution of clinical signs and possible complications of surgery was performed in all dogs. The median follow-up time for surviving dogs (8) was 11.5 months with a mean of 13 months. An excellent outcome was identified in five patients. Three dogs had a good outcome and one dog died of respiratory complications. Cervical pain was eliminated or significantly reduced in all dogs that survived and none of the dogs had major residual neurological deficits. Arthrodesis could not be confirmed on follow-up radiographs due to the presence of the polymethylmethacrylate; however, adequate stabilization of C1-C2 appears to have been achieved based on the resolution of clinical signs. Application of ventral pins and polymethylmethacrylate is an effective means of surgical treatment for congenital and traumatic AAI.

P-4-451 - Treatment of traumatic atlanto-axial instability. Indications, techniques, results and complications

Patients’ outcome following traumatic atlanto-occipital dislocation (AOD) has been poor. In recent years, an increasing number of patients surviving the initial trauma are admitted to hospital. In order to further improve the management of these patients, the knowledge of diagnostics and therapy as well as possible complications should be increased.The aim of this study was to evaluate diagnostic parameters, therapy, early complications and outcome of patients with traumatic AOD.Monocentric retrospective cohort study.A total of 12 patients were included in this study.The main outcome measure was functional patient outcome. Furthermore, radiographic and treatment data were analyzed.All patients suffering from traumatic AOD within an 8-year time period were included. Demographic data, radiological diagnostic parameters (condylar sum, basion dens interval, basion axis interval, power´s ratio, x-line method), as well as treatment data and complications of every patient were analyzed. Radiological parameters were compared with each other. Outcome was analyzed by a follow up examination.The accident mechanisms were motor vehicle accidents (MVA), fall from high and low height. Basion dens interval, basion axis interval, power's ratio and x-line method were not reliable in identifying traumatic AOD (only up to 33% of the patients were identified). Twelve patients could be reviewed. Three patients were treated with surgery, five patients were treated nonsurgically. Four patients died before surgical therapy. All seven surviving patients (survival rate: 58.3%) were re-examined (mean follow-up time: 6.7 months). All patients had a GCS of 15. Three surviving patients suffered from persisting neurological deficits.The most reliable way to diagnose AOD in Computer Topography is using the condylar sum. Surgical and nonsurgical measures can be employed with reasonable outcomes. Patient specific injury burden and clinical presentation should be taken into account when making treatment decisions for AOD.

Vertebrobasilar Insufficiency Resulting from Traumatic Atlantoaxial Instability

Vertebrobasilar ischemia revealed atlantoaxial instability in a patient who had cervical spine trauma 2 years previously. Vertigo was elicited by rotation of the head to the right; angiography demonstrated the occlusion of the left vertebral artery in the same position. The patient recovered totally after surgical fusion of the atlantoaxial joint.

Vertebrobasilar Insufficiency Resulting from Traumatic Atlantoaxial Instability

Vertebrobasilar Insufficiency Resulting from Traumatic Atlantoaxial Instability