Atypische dislozierte Densfraktur Typ II mit rotatorischer atlantoaxialer Luxation nach Reitunfall

We present a rare case of a combined dislocated odontoid dens fracture type II (Anderson/D’Alonzo) and rotational atlantoaxial luxation in a 15-year-old girl who was involved in a riding accident. She fell off her horse after it had stopped suddenly, losing consciousness for a few minutes. At presentation in the hospital, she had no complaints other than limited, painful neck movement. Radiologically, a posterior dislocation of an odontoid type II fracture (Anderson/D’Alonzo) was found. Computed tomography reconstruction demonstrated a rotational, hooklike fixed luxation of the left atlantoaxial facet joint. Manual repositioning after application of a cervical collar failed. Therefore, operative treatment was indicated for this highly unstable fracture. Posterior transarticular atlantoaxial screw fixation according to Magerl was performed; an iliac corticocancellous bone graft was harvested and shaped to conform to the posterior processes of C1 and C2. Additionally a hook-claw atlas fixation of C1 was done. To our knowledge, this is the first case of adolescent atlantoaxial cervical spine trauma in combination with an odontoid fracture and fixed rotational luxation reported in literature.     

应用经关节螺钉固定在寰枢关节不稳中的生物力学研究与临床应用

目的 探讨后路经关节螺钉固定(Magerl技术)加植骨融合治疗寰枢关节不稳定的生物力学特性及其临床价值.方法 生物力学研究:取新鲜冰冻尸体标本30具,随机分成5组:完整标本组、寰枢椎不稳实验模型组、寰枢椎后路椎弓根螺钉固定组、寰枢椎经关节螺钉固定组及寰枢椎经关节螺钉联合Brooks钢丝固定组,每组各6具.标本施加±1.5N·m纯力偶矩作为加载的最大力矩,模仿前屈、后伸,左、右侧弯,左、右轴向旋转6种生理性运动,测量各种生理性运动的活动范围(ROM)和中性区(NZ)值.应用SPSS 11.0软件进行统计分析,比较组间差异.临床研究:2000年2月至2005年1月应用寰枢椎经关节螺钉(Magerl技术)固定、C1.2棘突间植骨融合术治疗寰枢椎不稳患者23例,男16例,女7例;年龄17～62岁,平均38.6岁;先天性畸形致脱位3例,外伤性脱位20例.所有患者进行定期随访和影像学检查,评估颈椎稳定性和植骨融合率.结果 标本生物力学测试结果表明:屈伸稳定性、侧弯稳定性和轴向稳定性均为寰枢椎经关节螺钉联合Brooks钢丝固定组＞寰枢椎经关节螺钉固定组＞寰枢椎椎弓根螺钉固定组＞寰枢椎完整标本组＞寰枢椎不稳模型组,组间差异有统计学意义.临床研究表明:23例共放置经关节螺钉46枚;无一例发生椎动脉损伤、脊髓损伤或舌下神经麻痹等并发症.23例患者均获随访,随访时间4～36个月,平均15个月;随访中2例患者主诉旋转活动部分受限;影像学检查提示所有患者植骨全部融合.结论 单纯的Magerl螺钉固定失稳的寰枢关节具有足够坚固的生物力学性能,临床上结合棘突间植骨可达到满意的骨性融合.     

Gallie结合单侧Magerl内固定法治疗寰枢椎不稳的生物力学研究

目的 对Gallie+单侧Magerl内固定技术治疗寰枢椎不稳进行生物力学评估.方法 10具成年国人甲醛固定的枕颈(C0～C4)标本,对寰枢椎不稳模型分别行Gallie内固定、Gallie+单侧Magerl内固定、双侧Magerl内固定,在颈椎三维运动试验机上对颈椎施加2.0 N×M纯力偶矩,产生前屈/后伸,左/右侧屈和左/右旋转6种生理运动,测量其三维运动范围(ROM).结果 单侧Magerl+Gallie法固定,其屈/伸ROM为1.66度,侧屈为0.5l度,轴向旋转为6.22度,与Gallie固定法比较,ROM分别减少78%、86%、69%,差异有统计学意义(P＜0.05).双侧Magerl法固定,其屈/伸ROM变为1.48度,侧屈为0.46度,轴向旋转为5.38度,与单侧Magerl+Gallie法比较,ROM减少其差异无统计学意义(P＞0.05).结论 Gallie+单侧Magerl固定法治疗寰枢椎不稳的生物力学稳定性与双侧Magerl法接近.     

Traumatic bilateral rotatory C1-C2 dislocation in an adult: case report and review of the literature

Trauma led to bilateral rotatory atlantoaxial dislocation in a 23-year-old woman. Clinical diagnosis of this uncommon dislocation of the cervical spin is generally difficult and often made late. Typical signs include pain in the upper cervical spine and a fixed rotated position of the head. Integrity of the transverse ligament of the atlas is a determining factor for atlantoaxial stability and allows orthopedic treatment after reduction using moderate traction on the head. As for most authors, orthopedic was successful in our patient who totally recovered cervical spine mobility without pain.     

Traumatic atlantoaxial rotatory dislocation with odontoid fracture: case report and review

STUDY DESIGN: A case of traumatic rotatory dislocation associated with odontoid fracture is reported. OBJECTIVES: To report a rare case of traumatic rotatory dislocation associated with odontoid fracture, and to discuss the mechanism underlying spinal instability and management. SUMMARY OF BACKGROUND DATA: This case is a cross between traumatic rotatory fixation and atlantoaxial rotatory dislocation. Classification of rotatory subluxation change after osteosynthesis of the odontoid process was undertaken. METHODS: A 24-year-old man sustained head and cervical injury after jumping. A Type 2 odontoid fracture without displacement was noted. RESULTS: Without further traumatic event, 1 month after injury, computed tomography scan showed posterior displacement of the odontoid fracture and Type 4 or B atlantoaxial rotatory luxation. After surgical fixation and reduction of the odontoid fracture, the rotatory subluxation classification changed and became Type 1 or A. Posterior C1-C2 arthrodesis was performed. The patient wore a Philadelphia cervical collar for 3 months and underwent physiotherapy. CONCLUSIONS: As the pivot of rotatory subluxation changed after odontoid process osteosynthesis, posterior C1-C2 arthrodesis was performed. The patient probably could have been treated in a single-stage procedure using posterior C1-C2 transarticular fixation with bicortical interspinous graft.     

Minimally invasive lateral mass plating in the treatment of posterior cervical trauma: surgical technique

OBJECTIVE: The technique of lateral mass fixation restores the posterior tension band and provides effective stabilization in patients with many types of traumatic injuries. However, postoperative wound pain is not uncommon. The objective of this work is to describe a modified technique of minimally invasive lateral mass plating for cervical spine trauma. METHODS: Patient 1 was a 64-year-old woman who had been in a motor vehicle accident and sustained bilateral C5-C6 facet dislocation with posterior C5-C6 distraction. She was otherwise neurologically intact, and attempts at closed reduction were not successful. Patient 2 was a 16-year-old girl who had also been in a motor vehicle accident but had an incomplete spinal cord injury. She had an unstable burst fracture of C7 with posterior C5-C6 distraction. Both patients underwent anterior cervical fusion followed by staged minimally invasive posterior fusion with good results. A dilator tubular retractor system (METRX) was used to access the bilateral lateral masses through a small midline incision under fluoroscopic guidance. Lateral mass screws were then placed by using a modified Magerl technique, securing two-hole plates on each side onto the lateral masses, performed through the METRX system. We also successfully performed four-level lateral mass plating in a cadaveric cervical spine using a 2-cm skin incision. CONCLUSIONS: We describe successful placement of lateral mass screw and plate constructs with the use of a minimally invasive approach by means of a tubular dilator retractor system. This approach preserves the integrity of the muscles and ligaments that maintain the posterior tension band of the cervical spine.     

Traumatic atlantoaxial rotatory dislocation in adults

Pure traumatic atlantoaxial rotatory dislocation (TAARD) is a possible cause of torticollis in children, but very rare in adults. Aim of this study is to report three very rare cases of TAARD in adults, focusing anatomy, management, and outcome. All 3 patients had a head-on automobile accident. Cases included a 26-year old woman, a 21-year old woman, and a 29-year-old man. The first case had a 45-day delay in diagnosis; the second and third cases were suspected to have odontoid lateral mass asymmetry on transoral radiographs. In all cases CT scan confirmed diagnosis and clarified the type of subluxation. All had conservative treatment with reduction and immobilization with Halo-Vest for case 1 and 2, and a rigid cervical collar for case 3. After follow-up of 10 years for case 1 and 2, and 3 years for case 3, all had no sign of C1-C2 complex mobility/instability. Patients 2 and 3 had complete and pain free cervical spine range of motion, while case 1 had stiffness and straightness of the cervical spine, headache, and nerve roots deficits, probably due to the complex cervical spine injury with sagittal imbalance on X-ray and C5-C6 spinal cord compression (pre-existing the trauma). TAARD should be considered in the differential diagnosis of post-traumatic neck pain and limitation, with or without evident torticollis, even in adults. CT scan is mandatory for a correct evaluation of C1-C2 complex. Conservative treatment with reduction followed by 50-60 days of rigid cervical immobilization (3 months in delayed diagnosis) is usually effective. Delay in diagnosis could be the cause of a poor outcome.     

Nontraumatic posterior atlantooccipital dislocation associated with atlantoaxial instability

Introduction

Nontraumatic posterior atlantooccipital dislocation has only been rarely reported. In the current study, the authors reported an extremely rare case of nontraumatic posterior atlantooccipital dislocation associated with atlantoaxial instability.

Materials and methods

A 47-year-old female was referred with a history of neck pain for 5 years. The patient had no history of trauma. The axial rotation of range of motion of the cervical spine was severely restricted. Posterior atlantooccipital dislocation with atlantoaxial instability was confirmed through conventional radiography, computed tomography and magnetic resonance imaging. We performed realignment of the dislocation and posterior occipitocervical (C0–C2) fusion. After the surgery, the patient’s symptoms improved significantly and she manifested neurological improvement.

Conclusion

To our knowledge, this lesion has not been reported previously. Anomalies of upper cervical spine may have induced this instability.

     

Septic arthritis of the atlantoaxial joint: case report

Bacterial epidural abscess formation of cervical spine was rarely seen and all these cases were associated with osteomyelitis of the odontoid process. To the author's knowledge, only 1 case of septic arthritis of the C1-C2 lateral facet joint has been reported in the English literature. A 76-year-old woman presented with progressive neck pain and stiffness in the left side of her neck with fever. Coronal computed tomography clearly demonstrated destructive change of the atlantoaxial joint. Contrast magnetic resonance imaging demonstrated infection of the atlantoaxial joint resulting in epidural abscess formation. Because of lack of neurologic deficit, we treated her with halo-fixation together with appropriate antibiotics administration. The patient was successfully treated with antibiotics and immobilization. Septic arthritis of the lateral atlantoaxial joint should be added to the differential diagnosis of severe neck pain with fever, although it is very rare clinical entity. Early analysis of computerized tomography and magnetic resonance imaging although maintaining a high suspicion for this disease is mandatory to avoid delayed diagnosis and subsequent morbidity.     

寰枢椎后路椎弓根螺钉固定的生物力学评价

目的：评价寰枢椎后路椎弓根螺钉固定的生物力学稳定性。方法：6具新鲜颈椎标本，按随机顺序，对每一标本先后行C1-C2椎弓根螺钉、Magerl螺钉、Brooks钢丝以及螺钉联合钢丝固定，在脊柱三维运动实验机上测量其三维运动范围。结果：Magerl螺钉或C1-C2椎弓根螺钉联合Brooks钢丝组成的固定系统的三维运动范围最小。C1-C2椎弓根螺钉固定的前后屈伸运动范围与Brooks钢丝固定无差异，但大于Magerl螺钉；其左右侧屈运动范围小于Brooks钢丝固定，大于Magerl螺钉；其轴向旋转角度明显小于Brooks钢丝固定，但与Magerl螺钉无统计学差异。结论：C1-C2椎弓根螺钉的三维稳定性与Magerl螺钉相当，联合Brooks钢丝固定可进一步提高其稳定性。     

前路经枢椎体至寰椎侧块螺钉内固定三维稳定性的实验研究

目的：评价前路经枢椎体至寰椎侧块螺钉内固定三维稳定性。方法：16具成人标本（C0–C3）,对每一标本分别测定完整状态（第1组）、齿状突Ⅱ型骨折（第2组）、后路经关节螺钉内固定术（Magerl技术）（第3组）、前路经枢椎体至寰椎侧块螺钉内固定（第4组）4种状态下的三维运动范围,并进行统计学分析。结果：1组与其他3组、2组与其他3组比较差异有统计学意义（P〈0.001）。前路经枢椎体至寰椎侧块螺钉内固定与后路Magerl螺钉内固定均能显著减少寰枢关节各方向运动范围,两种固定方法差异无统计学意义（P〉0.05）。结论：前路经枢椎体至寰椎侧块螺钉内固定的三维稳定性与后路Magerl螺钉内固定术相当,为寰枢椎不稳定及脱位患者的治疗提供了一种可靠的手术选择。     

Conservative treatment of an atlantoaxial degenerative articular cyst: case report

BACKGROUND: Atlantoaxial degenerative articular cysts are rare lesions that can cause extradural compression of the cervicomedullary junction. When symptomatic, they usually require surgical treatment. We report an unusual case of spontaneous regression of an atlantoaxial degenerative articular cyst after conservative treatment with an external cervical brace along with a systemic therapy with nonsteroidal anti-inflammatory drugs (NSAIDs) and steroids. We also discuss the potential pathogenetic mechanisms involved. PURPOSE: To describe a case of significant volume reduction of an atlantoaxial articular degenerative cyst in a patient treated with a Philadelphia collar and anti-inflammatory drugs. STUDY DESIGN: Case report with analysis of the literature. METHODS: A 80-year-old patient was admitted to our institution with a history of progressive tetraparesis, ataxic gait, and cervical pain. A cervical spine magnetic resonance imaging (MRI) scan showed an extradural mass lesion behind the dens of C2 causing significant compression of the cervicomedullary junction, suggesting the diagnosis of atlantoaxial degenerative articular cyst. The patient refused surgery in favour of a conservative treatment with a Philadelphia collar and a short-term course of NSAIDs and corticosteroids. RESULTS: After 6 weeks, the patient's neurological condition improved, and a 6-month follow-up cervical spine MRI scan revealed an almost complete regression of the atlantoaxial cystic lesion. At a 1-year follow-up, his clinical condition was further improved. CONCLUSIONS: Atlantoaxial articular degenerative cysts are rare lesions that should be included in the differential diagnosis of those extradural lesions that can cause a ventral or ventrolateral compression of the cervicomedullary junction. They most commonly occur in elderly female patients affected by diffuse arthrosic degeneration of the cervical spine, with or without clear radiological signs of atlantoaxial instability, and have a typical appearance on MRI imaging. Surgery, with direct excision of the cyst and/or a C1-C2 fusion, is the first treatment of choice. Nevertheless, our report points out the possibility of a significant spontaneous regression of these lesions following a simple conservative strategy based on the use of an external cervical brace together with a systemic anti-inflammatory therapy.     

Synovial cyst at the C1-C2 junction in a patient with atlantoaxial subluxation

Synovial cysts of the cervical spine causing myelopathy are rare. The pathogenesis of these cysts is often attributed to degenerative changes of the facet joints or microtrauma. The authors report a synovial cyst at the C1-C2 junction in a patient with atlantoaxial subluxation without a congenital anomaly or inflammatory conditions. A 72-year-old man presented with a progressive right-sided myelopathy attributed to a C1-C2 synovial cyst accompanied by atlantoaxial subluxation and C3-C6 spondylosis. Magnetic resonance imaging of the cervical spine showed a large cystic mass compressing the spinal cord located at the C1-C2 junction. A C1 hemilaminectomy, complete evacuation of the cyst contents, and posterior atlantoaxial fusion were performed, and a double-door laminoplasty was also done at C3-C6. The patient showed significant improvement of paresthesia and motor weakness of the right upper and lower extremities immediately after the operation. Synovial cysts should be considered in the differential diagnosis of an extradural mass of the upper cervical spine. Posterior fusion combined with direct excision of the cyst may be the optimum treatment of a synovial cyst at the C1-C2 junction in a patient with atlantoaxial subluxation.     

寰枢椎脱位后路螺钉固定方法的临床选择

目的 探讨寰枢椎脱位后路钉棒固定术中寰椎螺钉和枢椎螺钉固定方法 的临床选择.方法 对2002 年11 月至2011 年12 月广州军区广州总医院收治的228 例可复性和23 例难复性寰枢椎脱位患者,术前进行置钉可行性和复位可能性评估,针对性地选择寰椎和枢椎的后路螺钉固定方法,进行寰枢椎后路钉棒固定治疗.结果 251 例患者均行钉棒固定并获得满意复位.寰椎螺钉固定采用椎弓根螺钉403 枚、部分经椎弓根螺钉77 枚、侧块螺钉22 枚;枢椎螺钉固定采用椎弓根螺钉437 枚、椎板螺钉56 枚、侧块螺钉9 枚.术中未发生椎动脉、脊髓损伤.237 例患者获得随访,随访时间4～38 个月,平均随访时间13 个月.230 例患者获骨性融合;6例为纤维愈合,动力位片（均随访2 年以上）未见复发脱位;另1 例为假关节未融合并双侧枢椎椎弓根螺钉松动,行后路翻修手术治愈.结论 根据寰枢椎脱位的复位难易程度和个体解剖特点灵活选择寰椎和枢椎不同的后路螺钉固定方法,扩大了寰枢椎后路钉棒固定技术的适用范围,提高了手术安全性和成功率.     

Minimally invasive lateral mass screws in the treatment of cervical facet dislocations: technical note

OBJECTIVE: The technique of lateral mass screw and rod or plate fixation is a major advancement in the posterior instrumentation of the cervical spine. This technique provides rigid three-dimensional fixation, restores the dorsal tension band, and provides highly effective stabilization in patients with many types of traumatic injuries. METHODS: Patient 1 was a 32-year-old man who had been in a motor vehicle accident. He presented with right C5 radiculopathy. X-ray findings included 45% anterolisthesis of C4 on C5, bilateral facet disruption, and right unilateral C4-C5 facet fracture and dislocation. The patient was placed in Gardner-Wells tongs, and the fracture was reduced with 25 pounds of traction. Patient 2 was a 56-year-old woman who had been in a motor vehicle accident that resulted in complete quadriplegia. Her initial imaging studies revealed a C3-C4 right unilateral facet fracture with subluxation. She was placed in traction, and her neurological status was reassessed. The findings of her neurological examination revealed improvement: she was found to have Brown-Séquard syndrome. Patient 3 was a 33-year-old man who was involved in a diving accident that resulted in bilaterally jumped facets at C3-C4. The patient was neurologically intact, and attempts at closed reduction were not successful. RESULTS: Patients 1 and 2 underwent anterior cervical discectomy with iliac crest autograft fusion and plating. They were then placed in the prone position, and a dilator tubular retractor system was used to access the facet joint at the level of interest. The facet joints were then denuded and packed with autograft. Lateral mass screws were then placed by means of the Magerl technique, and a rod was used to connect the top-loading screws. Patient 3 underwent posterior surgery that included only removal of the superior facet, intraoperative reduction, and bilateral lateral mass screw and rod placement. CONCLUSION: This technical note describes the successful placement of lateral mass screw and rod constructs with the use of a minimally invasive approach by means of a tubular dilator retractor system. This approach preserves the integrity of the muscles and ligaments that maintain the posterior tension band of the cervical spine.     

The role of torsion in cervical spine trauma

A dynamic servocontrolled torsion machine has been used to characterize cervical injury due to pure rotation of the head. Resultant force moment, torque, and applied rotation have been measured. Torque applied to the base of the skull resulted in injury to the atlantoaxial joint. No evidence of lower cervical injury was observed by computed tomography, magnetic resonance imaging, in situ fluoroscopy, or visual inspection. Torque applied directly to the lower cervical spine induced ligamentous injury and unilateral facet dislocation; however, the torque to injure the lower cervical spine was significantly greater than the torque to injure the atlantoaxial joint. It was concluded that pure rotation of the head does not mediate lower cervical ligamentous injury because of the comparative weakness of the atlantoaxial joint.     

Hangman's fracture caused by suspected child abuse. A case report

This report highlights the difficulties associated with diagnosing cervical spine injuries in children especially as the history and mechanism of injury may often be unclear and the normal variations in roentgenographic appearance may be confusing. As far as we are aware this is only the second case of traumatic Hangman's fracture in a child under the age of 3 years and the only case where there is a strong probability of child abuse. A female child aged 23 months was admitted with a 5-day history of irritability and general malaise. Her father reported noticing that she was reluctant to move her neck. He denied any possibility of trauma. On admission she had neck stiffness with a temperature of 37 degrees C and supported her neck with her hands. There was evidence of otitis media of her right ear. Her physical examination was otherwise normal. A full blood count and lumbar puncture were within normal limits. Cervical spine x rays suggested a Hangman's fracture of C2 with slight anterior subluxation of C2 on C3 and a kyphus at that level. Computerized Tomography demonstrated no significant canal encroachment. An isotope bone scan was non-diagnostic. She was treated in a moulded cervical collar with neck held in slight extension. Her symptoms resolved and further radiographs showed improved alignment. Repeat CT scans seven weeks post admission showed callus formation. At follow-up at one year she remains asymptomatic. Hangman's fracture is very rare in children under 3 years and the considerable normal variations further complicate diagnosis. Swischuk described the posterior cervical line connecting the spinous process of C1-C3 vertebrae on the lateral projection to differentiate a true fracture dislocation from physiological anterior displacement. A detailed history, roentgenograms, bone scans, CT scans and MRI scans are often required for accurate diagnosis.     

寰枢关节不稳或脱位患者上颈椎曲度改变对下颈椎的影响

目的:探讨寰枢关节不稳或脱位患者上颈椎的曲度变化对下颈椎力线和退变的影响.方法:在148例寰枢关节不稳定或脱位患者的颈椎中立位X线片上测量CO-1、C1-2、CO-2及C2-7角度,评估颈椎间盘的退变程度.分析上、下颈椎曲度之间以及颈椎曲度与年龄、病程之间的相关性,观察不同年龄组上颈椎曲度对下颈椎椎间盘退行变的影响.结果:CO-1角度为-22.9°18.6°(n=88);CI-2角度为-31.7°～39.1°(n=88);CO-2角度为-35.2°～44.8°(n=148);C2-7角度为-17.4°77.8.(n=148).C1-2和C2-7角度之间、C0-2与C2-7角度间、C0-1与C1-2角度之间存在显著负相关性.上、下颈椎曲度与病程、年龄无相关性.30～39岁组、40～49岁组及50～59岁组C5/6椎间盘退变、60岁以上组C2/3椎间盘退变与上颈椎角度(C0-2角度)之间存在显著负相关.结论:上、下颈椎曲度间存在密切关系,寰椎前脱位可导致下颈椎出现代偿性过度前凸,即鹅颈畸形,鹅颈畸形可能加速下颈椎的退变进程.     

Temporäre perkutane Spondylodese C1/2 und Halotransfixation

Dislocated combined injuries of the upper cervical spine such as C 1/2 fractures require occipitocervical fusion, especially if the dislocation can not be redressed using halo vest immobilisition. We report on the clinical course and outcome of a young woman who sustained complex cervical spine injuries. Closed reduction and a percutaneous transfixation of C 1/2 with k-wires (Magerl) and an additional halo vest immobilisition was performed to avoid permanent fusion. The 25 year old patient was involved in a motor vehicle accident that resulted in a dislocated Jefferson's fracture, an odontoid fracture type II (Anderson and d'Alonso) with protrusion into the foramen magnum, and a dislocated C 6/7 fracture. A ventral spondylodesis C6/7 was followed by temporary dorsal spondylodesis C1/2 with k-wires (Magerl) and additional halo vest immobilisition after closed reduction. The temporary percutaneous fixation C1/2 was removed after 11 weeks, as was the halo vest immobilisition. After removing the temporary percutaneous fixation (k-wires) and the halo system, the patient showed very good functional results in terms of range of motion with only minor discomfort. Complex injuries of the upper cervical spine that cannot be retained by external fixation often require an occipitocervical fusion or fixation of C1/2. In the case presented, the temporary percutaneous fixation (Magerl) with k-wires was terminated after 3 months to avoid significant functional impairment. Younger patients benefit most from temporary fusion of the upper cervical spine, which results in better functional outcome and only minor pain.     

Atlantoaxial Subluxation in Different Intraoperative Head Positions in Patients with Rheumatoid Arthritis

Background: Disorders of the cervical spine are often observed in patients with rheumatoid arthritis (RA). However, the best head position for RA patients with atlantoaxial subluxation in the perioperative period is unknown. This study investigated head position during general anesthesia for the patients with RA and proven atlantoaxial subluxation.

Methods: During anesthesia of patients with RA and proven atlantoaxial subluxation, the authors used fluoroscopy to obtain a lateral view of the upper cervical spine in four different positions: the mask position, the intubation position, the flat pillow position, and the protrusion position. Copies of the still fluoroscopic images were used to determine the anterior atlantodental interval, the posterior atlantodental interval, and the angle of atlas and axis (C1-C2 angle).

Results: The anterior atlantodental interval was significantly smaller in the protrusion position (2.3 mm) than in the flat pillow position (5.1 mm) (P < 0.05). The posterior atlantodental interval was significantly greater in the protrusion position (18.9 mm) than in the flat pillow position (16.2 mm) (P < 0.05). The C1-C2 angle was, on average, 9.3[degrees] greater in the protrusion position than in the flat pillow position (P < 0.05).