[A man with rheumatoid arthritis and a painful neck]

An 80-year-old man with long-standing rheumatoid arthritis presented with severe neck pain. No preceding trauma had occurred and he had no neurological complaints. A CT scan revealed vertical atlanto-axial subluxation without compression of the medulla oblongata. After conservative treatment the pain diminished. There were no neurological complications at follow-up.

Motion and dural sac compression in the upper cervical spine during the application of a cervical collar in case of unstable craniocervical junction-A study in two new cadaveric trauma models

Background

Unstable conditions of the craniocervical junction such as atlanto-occipital dislocation (AOD) or atlanto-axial instability (AAI) are severe injuries with a high risk of tetraplegia or death. Immobilization by a cervical collar to protect the patient from secondary damage is a standard procedure in trauma patients. If the application of a cervical collar to a patient with an unstable craniocervical condition may cause segmental motion and secondary injury to the spinal cord is unknown.

The aim of the current study is (i) to analyze compression on the dural sac and (ii) to determine relative motion of the cervical spine during the procedure of applying a cervical collar in case of ligamentous unstable craniocervical junction.

Methods and findings

Ligamentous AOD as well as AOD combined with ligamentous AAI was simulated in two newly developed cadaveric trauma models. Compression of the dural sac and segmental angulation in the upper cervical spine were measured on video fluoroscopy after myelography during the application of a cervical collar. Furthermore, overall three-dimensional motion of the cervical spine was measured by a motion tracking system.

In six cadavers each, the two new trauma models on AOD and AOD combined with AAI could be implemented. Mean dural sac compression was significantly increased to -1.1 mm (-1.3 to -0.7 mm) in case of AOD and -1.2 mm (-1.6 to -0.6 mm) in the combined model of AOD and AAI. Furthermore, there is a significant increased angulation at the C0/C1 level in the AOD model. Immense three-dimensional movement up to 22.9° of cervical spine flexion was documented during the procedure.

Conclusion

The current study pointed out that applying a cervical collar in general will cause immense three-dimensional movement. In case of unstable craniocervical junction, this leads to a dural sac compression and thus to possible damage to the spinal cord.

The relationship between the degree of displacement of the atlas to axis and the clinical data in atlanto-axial subluxation due to rheumatoid arthritis

INTRODUCTION

The most common type of anatomical cervical spine involvement is atlanto-axial subluxation (AAS) in rheumatoid arthritis (RA). The purpose of this study was to clarify the relationship between the displacement of the atlas to axis and the clinical data obtained in patients with AAS due to RA.

METHODS

Fifty patients with AAS due to RA that were treated by surgery are herein reviewed. Based on the findings of preoperative lateral cervical radiographs in the neutral position, the patients were classified into two groups as follows: a 10 + group with an atlanto-dental interval (ADI) of ≧ 10 mm, and a 10 - group with an ADI < 10 mm.

RESULTS

Preoperative lateral cervical radiographs demonstrated 15 cases to belong to the 10 + group, while 35 cases belonged to the 10 - group. In the preoperative MR imaging, an intramedullary high signal intensity was observed in seven cases that belonged to the 10 + group and in four cases belonging to the 10 - group. Regarding the neurological severity, the 10 + group included significantly more cases showing severe neurological deficits before surgery; however, there was no significant difference between the two groups regarding the presence of severe deficits even after surgery.

CONCLUSIONS

The severe displacement group included significantly more cases showing an intramedullary high signal intensity in the preoperative MR images. Our results also suggest that a severe displacement before surgery affected the presence of neurological deficits before surgery; however, it did not affect the neurological recovery from such severe neurological deficits.

Acute Traumatic Cervical Cord Injury in Pediatric Patients with os Odontoideum: A Series of 6 Patients

OBJECTIVE

Os odontoideum can lead to instability of the atlantoaxial joint and places the spinal cord at significant risk for acute traumatic catastrophic events or chronic neurologic change. The purpose of this study was to retrospectively review acute cervical cord injury after minor trauma in 6 pediatric patients with os odontoideum.

METHODS

Between 2012 and 2013, 6 pediatric patients with os odontoideum who suffered acute traumatic cervical cord injury were reviewed retrospectively. Their clinical history, neurologic symptoms, radiological investigations, follow-up period, American Spinal Injury Association (ASIA) impairment classification, and motor score were reviewed.

RESULTS

There were 2 male and 4 female subjects ranging in age from 4 to 18 years (mean 11.8 years). Before the traumatic injury, 2 cases were asymptomatic and 4 complained of myelopathic feature with unsteadiness on feet. Falls were the most common injury (n = 5), followed by a minor motor vehicle accident (n = 1). Atlantoaxial instability and cord compression were presented in all cases with dynamic cervical lateral radiographs and magnetic resonance imaging. Most patients presented with spinal cord thinning and hyperintensity on T2-weighted sequences in magnetic resonance imaging. Spinal cord compression was anterior in 2 cases and both anterior and posterior in 4. Two patients was classified as ASIA B, 1 as ASIA C, and 3 as ASIA D category on admission. Two patients presented with respiratory failure with mechanical ventilation for over 2 weeks in perioperative period. Postoperatively, all patients improved neurologically and clinically after underwent posterior atlantoaxial fixation and fusion.

CONCLUSIONS

Pediatric patients with asymptomatic or myelopathic atlantoaxial instability secondary to os odontoideum are at risk for acute spinal cord injury even after minor traumatic injury. Sufficient fixation and fusion should be undertaken as prophylactic treatment of developing myelopathy and to improve neurologic symptoms with acute traumatic cervical cord injury in pediatric patients with os odontoideum.

[Cervical spine instability in the surgical patient]

Many congenital and acquired diseases, including trauma, may result in cervical spine instability. Given that airway management is closely related to the movement of the cervical spine, it is important that the anesthesiologist has detailed knowledge of the anatomy, the mechanisms of cervical spine instability, and of the effects that the different airway maneuvers have on the cervical spine. We first review the normal anatomy and biomechanics of the cervical spine in the context of airway management and the concept of cervical spine instability. In the second part, we review the protocols for the management of cervical spine instability in trauma victims and some of the airway management options for these patients.

Bilateral C1-C2 transarticular screw and C1 laminar hook fixation and bone graft fusion for reducible atlantoaxial dislocation: a seven-year analysis of outcome

BACKGROUND

Bilateral C1-2 transarticular screw and C1 laminar hook fixation was developed on the basis of transarticular screws fixation. The modified technique has showed a better biomechanical stability than established techniques in previous study. However, long-term (minimum follow-up 7 years) outcomes of patients with reducible atlantoaxial dislocation who underwent this modified fixation technique have not still been reported.

METHODS

A retrospective study was conducted to evaluate the outcome of 36 patients who underwent this modified technique. Myelopathy was assessed using the Ranawat myelopathy score and Myelopathy Disability Index. Pain scores were assessed using Visual Analogue Scale. Radiological imaging was assessed and the following data were extracted: the atlantodental intervals, the space available for cord, presence of spinal cord signal change on T2 weighted image, C1-C2 angle, C2-C7 angle and fusion rates.

FINDINGS

All patients achieved a minimum seven-year follow up. 95% patients with neck and suboccipital pain improved after surgery; in their Visual Analogue pain scores, there was a greater than 50% improvement in their VAS scores with a drop of 5 points on the VAS (P<0.05). 92% of patients improved in the Ranawat myelopathy grade; the Myelopathy Disability Index assessment showed a preoperative mean score of 35.62 with postoperative mean 12.75(P<0.05). There was not any significant atlantoaxial instability at each follow-up time. The space available for cord increased in all patients. Postoperative sagittal kyphosis of the subaxial spine was not observed. After six months after surgery, bone grafts of all patients were fused. No complications related to surgery were found in the period of follow-up.

CONCLUSIONS

The long-term outcomes of this case series demonstrate that under the condition of thorough preoperative preparations, bilateral C1-C2 transarticular screw and C1 laminar hook fixation and bone graft fusion is a reliable posterior atlantoaxial fusion technique for reducible atlantoaxial dislocation.

[Biomechanical study of atlantoaxial fixation for transverse ligament injury leading to atlantoaxial instability]

OBJECTIVE

To explore the three-dimensional movement of atlantoaxial joint, complete transverse ligament and cracked transverse ligament after posterior atlantoaxial fixation.

METHODS

The fresh upper cervical cadaveric specimens were collected from 6 males dead from active craniocerebral injury. The average age was 39.7 years old (range: 26 - 57). The specimens were divided into 3 groups of intact (Group I), transverse ligament cracked (Group D) and posterior atlantoaxial fixation (Group F). They were tested consecutively.

RESULTS

The range of sagittal movement increased when the transverse ligament became cracked. And it had significant difference compared with the Group I (P < 0.05). But the ranges of lateral flexion and rotation showed no significant difference. When posterior atlantoaxial fixation was performed, all three-dimensional movements decreased. And significant differences existed as compared with Group I (P < 0.05).

CONCLUSION

Under normal conditions, the main movement of atlantoaxial joint is rotation with lesser sagittal movement and lest lateral flexion. The range of sagittal movement increases significantly when transverse ligament is cracked (P < 0.05), especially so for anteflexion movement. The increase of lateral flexion and rotation has no significant difference compared with Group I. When posterior atlantoaxial Fixation is performed, all three-dimensional movements decrease significantly as compared with Group I (P < 0.05), especially loss of rotation function.

[Treatment strategy of rotatory dislocation of atlantoaxial articulation in children]

OBJECTIVE

To analyze appropriate strategy about treatment of rotatory dislocation of atlantoaxial articulation in children.

METHODS

From March 2005 to February 2009, 36 patients with rotatory dislocation of atlantoaxial articulation were retrospectively analyzed, including 25 males and 11 females, with the average age of 7.8 years (ranged 3 - 14 years). According to Fielding-Hawkins clinical classification, type I 24 cases, type II 8 cases, type III 2 cases, type IV 2 cases. All of the patients were assessed rotatory dislocation of atlantoaxial articulation and whether or not upper cervical spine malformation by X-ray, MRI and CT scan and three-dimensional reconstruction. Thirty-two cases received observational treatments which were reduction after cervical traction, without appearance of the deformity, without neurological symptoms. And another 4 serious cases (irreducible atlantoaxial dislocation or with os odontoideum) received posterior atlantoaxial fixed autograft fusion.

RESULTS

Rotation of atlas decreased from 16.0° ± 4.4° (range, 5° to 26°) pre-therapy to 4.5° ± 1.5° (range, 0° to 8°) post-therapy in 35 cases, rotation of atlas had significant difference between pre-therapy and post-therapy (t = 14.75, P < 0.05). One patient pre-therapy rotation of atlas was 45°, post-therapy was 4°. All patients were followed up for 14 - 38 months (mean, 18 months), 32 cases who received cervical traction and external fixation resulted in satisfactory outcome in which all the ankylodeire were disappear, bilateral masses were symmetrical on anterior-posterior and good functional activities of cervical. All the 4 cases surgically treated obtained reduction, sound bony fusion and neural symptoms were improved obviously after operation.

CONCLUSIONS

Conservative treatment has been proved to be very effective in most of rotatory dislocation of atlantoaxial articulation in children. However, operative treatment should be considered in the following situations: irreducible atlantoaxial dislocation or patients with os odontoideum.

Bilateral anomaly of rectus capitis posterior muscles in the suboccipital triangle and its clinical implication

Rectus capitis posterior muscles are located in the suboccipital triangle and function in extension and lateral rotation of the head and neck. There are two of these muscles on each side: the rectus capitis posterior major and the rectus capitis posterior minor. In the present case we observed bilateral double rectus capitis posterior major muscle and bilateral absence of rectus capitis posterior minor muscle. The additional rectus capitis posterior major may put more strain to the spine of the axis and mean time the bilateral absence of rectus capitis posterior minor muscles will result in muscular in coordination in the suboccipital region while balancing the head. The present variation should be considered in the aetiology of cervicogenic headache.

Rheumatoid arthritis of the cervical spine--clinical considerations

Rheumatoid arthritis (RA) is a chronic, systemic inflammatory disorder affecting multiple organ systems, joints, ligaments, and bones and commonly involves the cervical spine. Chronic synovitis may result in bony erosion and ligamentous laxity that result in instability and subluxation. Anterior atlantoaxial subluxation (AAS) is the most frequently occurring deformity, due to laxity of the primary and secondary ligamentous restraints. Additional manifestations of RA include cranial settling, subaxial subluxation, or a combination of these. Although clinical findings can be confounded by the severity of multifocal joint and systemic involvement, a careful history is critical to identify symptoms of cervical disease; serial physical examination is the best noninvasive diagnostic tool. Thorough physical and neurologic examinations should be performed in all patients and serial functional assessments charted. Radiographs of the cervical spine with lateral flexion-extension dynamic views should be obtained periodically and used to "clear" the cervical spine before elective surgery requiring general anesthesia. Advanced imaging, such as magnetic resonance imaging (MRI) or myelography and computed tomography (CT), may be necessary to evaluate the neuraxis. Early initiation of pharmacotherapy may slow progression of rheumatoid cervical disease. Operative intervention before the onset of advanced myelopathy results in improved outcomes compared to the surgical stabilization of patients whose conditions are more advanced. A multidisciplinary approach involving rheumatology, surgery, and rehabilitation is beneficial to optimize outcomes.

A biomechanical rationale for C1-ring osteosynthesis as treatment for displaced Jefferson burst fractures with incompetency of the transverse atlantal ligament

Nonsurgical treatment of Jefferson burst fractures (JBF) confers increased rates of C1-2 malunion with potential for cranial settling and neurologic sequels. Hence, fusion C1-2 was recognized as the superior treatment for displaced JBF, but sacrifies C1-2 motion. Ruf et al. introduced the C1-ring osteosynthesis (C1-RO). First results were favorable, but C1-RO was not without criticism due to the lack of clinical and biomechanical data serving evidence that C1-RO is safe in displaced JBF with proven rupture of the transverse atlantal ligament (TAL). Therefore, our objectives were to perform a biomechanical analysis of C1-RO for the treatment of displaced Jefferson burst fractures (JBF) with incompetency of the TAL. Five specimens C0-2 were subjected to loading with posteroanterior force transmission in an electromechanical testing machine (ETM). With the TAL left intact, loads were applied posteriorly via the C1-RO ramping from 10 to 100 N. Atlantoaxial subluxation was measured radiographically in terms of the anterior antlantodental interval (AADI) with an image intensifier placed surrounding the ETM. Load-displacement data were also recorded by the ETM. After testing the TAL-intact state, the atlas was osteotomized yielding for a JBF, the TAL and left lateral joint capsule were cut and the C1-RO was accomplished. The C1-RO was subjected to cyclic loading, ramping from 20 to 100 N to simulate post-surgery in vivo loading. Afterwards incremental loading (10-100 N) was repeated with subsequent increase in loads until failure occurred. Small differences (1-1.5 mm) existed between the radiographic AADI under incremental loading (10-100 N) with the TAL-intact as compared to the TAL-disrupted state. Significant differences existed for the beginning of loading (10 N, P = 0.02). Under physiological loads, the increase in the AADI within the incremental steps (10-100 N) was not significantly different between TAL-disrupted and TAL-intact state. Analysis of failure load (FL) testing showed no significant differences among the radiologically assessed displacement data (AADI) and that of the ETM (P = 0.5). FL was Ø297.5 +/- 108.5 N (range 158.8-449.0 N). The related displacement assessed by the ETM was Ø5.8 +/- 2.8 mm (range 2.3-7.9). All specimens succeeded a FL >150 N, four of them >250 N and three of them >300 N. In the TAL-disrupted state loads up to 100 N were transferred to C1, but the radiographic AADI did not exceed 5 mm in any specimen. In conclusion, reconstruction after displaced JBF with TAL and one capsule disrupted using a C1-RO involves imparting an axial tensile force to lift C0 into proper alignment to the C1-2 complex. Simultaneous compressive forces on the C1-lateral masses and occipital condyles allow for the recreation of the functional C0-2 ligamentous tension band and height. We demonstrated that under physiological loads, the C1-RO restores sufficient stability at C1-2 preventing significant translation. C1-RO might be a valid alternative for the treatment of displaced JBF in comparison to fusion of C1-2.

[The application of C1-2 pedicle screw fixation in treating atlantoaxial instability]

OBJECTIVE

To explore the feasibility of C1-2 pedicle screw fixation and fusion technique in treating atlantoaxial instability.

METHODS

From January 2006 to January 2009,18 patients with atlantoaxial instability were treated with C1-2 pedicle screws and plates fixation under general anesthesia. There were 11 males and 7 females, the age for 17-62 years with the mean of 37.7 years. The course of disease was from 3 days to 30 months with an average of 10.6 months. The patients had different degrees neck pain and disturbance of sensation or (and) dyskinesia, had atlantoaxial instability from images before operation. The JOA scoring before operation were from 8 to 15 with an average of 11.4. Bone fusion of patients was observed with X-rays, CT and MR image at the same time after operation and the JOA scoring was compared with preoperative.

RESULTS

A total of 72 screws were successfully placed in 18 cases, among them, 15 cases were followed up from 6 to 24 months with an average of 11.5 months. Fifteen cases obtained bone fusion with time for 3-6 months without the complications of internal fixation failure or redislocation of atlas. The spinal compression had differently improved, postoperative JOA scoring was from 12 to 17 scores with an average of 14.5 scores.

CONCLUSION

Pedicle screw fixation and fusion in atlas has advantages of firm fixation and high fusion rate, it is a better choices for atlantoaxial instability. It is not suitable for variations of sulcus of vertebral artery of atlas and posterior arch of atlas.

[Biomechanical performance of different wires and cable fixation devices in posterior instrumentation for atlantoaxial instability]

OBJECTIVE

To compare the biomechanical performances of different wires and cable fixation devices in posterior instrumentation for atlantoaxial instability, and test the effect of different fixation strengths and fixation approaches on the surgical outcomes.

METHODS

Six specimens of the atlantoaxial complex (C0-C3) were used to establish models of the normal complex, unstable complex (type II odontoid fracture) and fixed complex. On the wd-5 mechanical testing machine, the parameters including the strength and rigidity of anti-rotation, change and strength of stress, and stability were measured for the normal complex, atlantoaxial instability complex, the new type titanium cable fixation system, Atlas titanium cable, Songer titanium cable, and stainless wire.

RESULTS

The strength and rigidity of anti-rotation, change and strength of stress, stability of flexion, extension and lateral bending of the unstable atlantoaxial complex fixed by the new double locking titanium cable fixation system were superior to those of the Songer or Atlas titanium cable (P<0.05) and medical stainless wire (P<0.05). Simultaneous cable fastening on both sides resulted in better fixation effect than successive cable fastening (P<0.05). Better fixation effect was achieved by fastening the specimen following a rest (P<0.05).

CONCLUSIONS

The fixation effects can be enhanced by increased fastening strengths. The new type double locking titanium cable fixation system has better biomechanical performance than the conventional Songer and Atlas titanium cables. Fastening the unstable specimens after a rest following simultaneous fastening of the specimen on both sides produces better fixation effect.

[Atlanto-axial screw-plate fixation and bone fusion for the treatment of atlanto-axial instability]

OBJECTIVE

To explore the clinical outcomes of atlanto-axial screw-plate fixation and bone fusion for the treatment of atlanto-axial instability.

METHODS

From June 2003 to June 2008,15 cases with atlanto-axial instability were treated with atlanto-axial lateral mass screw-plate fixation and self-cancellous bone graft fusion. There were 10 males and 5 females with the mean age of 41.7 years (range, from 19 to 72 years). Six cases were old odontoid fracture, 3 cases rheumatoid arthritis, 6 cases odontoid developmental deformity. All patients had symptoms and signs of upper cervical myelopathy and the imaging displayed atlanto-axial instability. JOA scores before operation were from 6 to 11 with an average of 7.4.

RESULTS

All patients were followed up with the mean of 28 months (range, from 9 to 40 months). The follow-up data indicated solid fusion in all patients, posterior reductions were satisfactory, no loosening or screw-plate broken was found. There were 10 cases which spinal cord function improved obviously, 4 cases improved slightly, 1 case no changed in the study. The postoperative JOA scores were from 13 to 17 with an average of 15.6.

CONCLUSION

Atlanto-axial screw-plate fixation and self-cancellous bone graft can stabilize atlas and axis, and promote fusion of atlanto-axial joint, which is an effective method for the treatment of atlanto-axial instability.

Biomechanical analysis comparing three C1-C2 transarticular screw salvaging fixation techniques

STUDY DESIGN

This is an in vitro biomechanical study.

OBJECTIVE

To compare the biomechanical stability of the 3 C1-C2 transarticular screw salvaging fixation techniques.

SUMMARY AND BACKGROUND DATA

Stabilization of the atlantoaxial complex is a challenging procedure because of its complicated anatomy. Many posterior stabilization techniques of the atlantoaxial complex have been developed with C1-C2 transarticular screw fixation been the current gold standard. The drawback of using the transarticular screws is that it has a potential risk of vertebral artery injury due to a high riding transverse foramen of C2 vertebra, and screw malposition. In such cases, it is not recommended to proceed with inserting the contralateral transarticular screw and the surgeon should find an alternative to fix the contralateral side. Many studies are available comparing different atlantoaxial stabilization techniques, but none of them compared the techniques to fix the contralateral side while using the transarticular screw on one side. The current options are C1 lateral mass screw and short C2 pedicle screw or C1 lateral mass screw and C2 intralaminar screw, or C1-C2 sublaminar wire.

METHODS

Nine fresh human cervical spines with intact ligaments (C0-C4) were subjected to pure moments in the 6 loading directions. The resulting spatial orientations of the vertebrae were recorded using an Optotrak 3-dimensional Motion Measurement System. Measurements were made sequentially for the intact spine after creating type II odontoid fracture and after stabilization with unilateral transarticular screw placement across C1-C2 (TS) supplemented with 1 of the 3 transarticular salvaging techniques on the contralateral side; C1 lateral mass screw and C2 pedicle screw (TS+C1LMS+C2PS), C1 lateral mass and C2 intralaminar screw (TS+C1LMS+C2ILS), or sublaminar wire (TS + wire).

RESULTS

The data indicated that all the 3 stabilization techniques significantly decreased motion when compared to intact in all the loading cases (left/right lateral bending, left/right axial rotation, flexion) except extension. All the 3 instrumented specimens were equally stable in extension/flexion and lateral bending modes. TS+C1LMS+C2PS was equivalent to TS+C1LMS+C2ILS (P > 0.05) and superior to TS + wire in axial rotation (P < 0.05). Also, TS+C1LMS+C2ILS was superior to TS + wire in axial rotation (P < 0.05).

CONCLUSION

Fixation of atlantoaxial complex using unilateral transarticular screw supplemented with contralateral C1 lateral mass and C2 intralaminar screws is biomechanically equivalent to C1 lateral mass and C2 pedicle screws and both are biomechanically superior to C1-C2 sublaminar wire in axial rotation.

[Clinical application of atlantoaxial pedicle screw internal fixation for treatment of atlantoaxial dislocation]

OBJECTIVE

To investigate the clinical effect of atlantoaxial pedicle screw internal fixation for treatment of atlantoaxial dislocation.

METHODS

Sixteen patients with atlantoaxial dislocation were treated from Dec. 2005 to June 2007, included 10 males and 6 females, aged from 38 to 45 years old (means 40.5 years). Among them 12 patients combined with nerve injury, according to ASIA grade: there were 3 cases in grade B, 5 cases in grade C, 4 cases in grade D. All patients received preoperative CT, radiograph and skull traction. Intraoperative posterior approach general spine pedicle screw-rod orthopaedics fixation system used and iliac bone block were implanted in space of posterior atlantal arch and axial vertebral plate. The outcome and complications were observed in the near future.

RESULTS

There was no vascular or neural injury found. The patients were followed up for 12 to 24 months (means 18 months). All head pain, acid storm symptoms were improved after operation. According to the Odom's clinical efficacy evaluation standard, 12 cases were excellent, 4 were good. Eleven cases of 12 with nerve injury recovered significantly. By ASIA classification: 1 cases was in grade B, 2 cases were in grade C, 5 cases were in grade D, 4 cases were in grade E. No looseness or breakage of screw occurred. Bony fusion was achieved in all cases.

CONCLUSION

Posterior approach atlantoaxial pedicle screw internal fixation have the advantages of direct screw placement, short-segment fusion, intraoperative reduction, fixation reliable, high fusion rate, and it can restablish the upper cervical vertebrae stability and help to recover the spinal cord and nerve function.

C2-fractures: part II. A morphometrical analysis of computerized atlantoaxial motion, anatomical alignment and related clinical outcomes

Knowledge on the outcome of C2-fractures is founded on heterogenous samples with cross-sectional outcome assessment focusing on union rates, complications and technical concerns related to surgical treatment. Reproducible clinical and functional outcome assessments are scant. Validated generic and disease specific outcome measures were rarely applied. Therefore, the aim of the current study is to investigate the radiographic, functional and clinical outcome of a patient sample with C2-fractures. Out of a consecutive series of 121 patients with C2 fractures, 44 met strict inclusion criteria and 35 patients with C2-fractures treated either nonsurgically or surgically with motion-preserving techniques were surveyed. Outcome analysis included validated measures (SF-36, NPDI, CSOQ), and a functional CT-scanning protocol for the evaluation of C1-2 rotation and alignment. Mean follow-up was 64 months and mean age of patients was 52 years. Classification of C2-fractures at injury was performed using a detailed morphological description: 24 patients had odontoid fractures type II or III, 18 patients had fracture patterns involving the vertebral body and 11 included a dislocated or a burst lateral mass fracture. Thirty-one percent of patients were treated with a halo, 34% with a Philadelphia collar and 34% had anterior odontoid screw fixation. At follow-up mean atlantoaxial rotation in left and right head position was 20.2 degrees and 20.6 degrees, respectively. According to the classification system of posttreatment C2-alignment established by our group in part I of the C2-fracture study project, mean malunion score was 2.8 points. In 49% of patients the fractures healed in anatomical shape or with mild malalignment. In 51% fractures healed with moderate or severe malalignment. Self-rated outcome was excellent or good in 65% of patients and moderate or poor in 35%. The raw data of varying nuances allow for comparison in future benchmark studies and metaanalysis. Detailed investigation of C2-fracture morphology, posttreatment C2-alignment and atlantoaxial rotation allowed a unique outcome analysis that focused on the identification of risk factors for poor outcome and the interdependencies of outcome variables that should be addressed in studies on C2-fractures. We recognized that reduced rotation of C1-2 per se was not a concern for the patients. However, patients with worse clinical outcomes had reduced total neck rotation and rotation C1-2. In turn, C2-fractures, especially fractures affecting the lateral mass that healed with atlantoaxial deformity and malunion, had higher incidence of atlantoaxial degeneration and osteoarthritis. Patients with increased severity of C2-malunion and new onset atlantoaxial arthritis had worse clinical outcomes and significantly reduced rotation C1-2. The current study offers detailed insight into the radiographical, functional and clinical outcome of C2-fractures. It significantly adds to the understanding of C2-fractures.

Specific entities affecting the craniocervical region: syndromes affecting the craniocervical junction

INTRODUCTION

The craniocervical junction is a vital component in understanding the function of the human central nervous system. It is the threshold for major pathways affecting both brain and spinal cord function, and these structures are intricately housed in a network of bone, ligaments, and soft tissues. Abnormal development of any of these components may lead to altered structure, and therefore, altered function in the central nervous system.

MATERIALS AND METHODS

We herein describe a set of genetic syndromes that commonly affect the craniovertebral junction and offer clinical examples from more than 6,000 patients who have been treated for these disorders.

DISCUSSION

The syndromes described include Chiari type I malformation, Conradi syndrome, Goldenhar syndrome, Klippel-Feil syndrome, Larsen syndrome, Morquio syndrome, Pierre-Robin syndrome, spondyloepiphyseal dysplasia congenital and Weaver syndrome. The genetic mechanisms responsible for these disorders may offer unique insight into the developmental pathways and patterning in the musculoskeletal and cranial systems and may, ultimately, guide future diagnosis and treatment.

[Anti-rotation biomechanical study of wire and various cable system in the posterior brooks instrumentation for atlantoaxial instability]

OBJECTIVE

To compare the anti-rotation biomechanical performances of wire and various cable fixation devices currently used in the posterior Brooks instrumentation for atlantoaxial instability.

METHODS

In this experiment,six specimens of the atlantoaxial complex (Occipital-C3) were used. The models of the normal complex,unstable complex (type II odontoid fracture) and fixed complex were established. On the WD-5 mechanics experimental machine,the parameters including the strength and rigidity of anti-rotation were quantified for the normal complex (group N),the atlantoaxial instability complex (group M), the new type Titanium cable (group A), Atlas titanium cable (group B), Songer Titanium cable (group C), stainless wire(group D).

RESULTS

The max strength of A, B, C, D groups was 12.5, 11.3, 11.52, 11.55 N x m respectively, the max rigidity was 58.81, 53.17, 54.11, 54.35 N x cm/deg respectively. The strength and rigidity of anti-rotation, compare to the unstable atlantoaxial complex which were fixed by the new double locking Titanium cable fixation system were superior to those of normal complex, instability complex, Songer or Atlas Titanium cable (P < 0.05).

CONCLUSION

Having been changed the locking method, the anti-rotation biomechanical characteristics of the new type double locking Titanium cable fixation system are superior or similar to the traditional Songer or Atlas Titanium cable.

Case report: nonoperative treatment of an unstable Jefferson fracture using a cervical collar

The treatment of unstable burst fractures of the atlas (Jefferson fractures) is controversial. Unstable Jefferson fractures have been managed successfully with either immobilization, typically halo traction or halo vest, or surgery. We report a patient with an unstable Jefferson fracture treated nonoperatively with a cervical collar, frequent clinical examinations, and flexion-extension radiographs. Twelve months after treatment, the patient achieved painless union of his fracture. The successful treatment confirms prior studies reporting unstable Jefferson fractures have been treated nonoperatively. The outcome challenges the clinical relevance of treatment algorithms that rely on the "rules of Spence" to guide treatment of unstable Jefferson fractures and illustrates instability may not necessarily be present in patients with considerable lateral mass widening. Additionally, it emphasizes a more reliable way of assessing C1-C2 stability in unstable Jefferson fractures is by measuring the presence and extent of anterior subluxation on lateral flexion and extension views.

In vivo segmental motion of the cervical spine in rheumatoid arthritis patients with atlantoaxial subluxation

OBJECTIVE

The dynamic mechanism underlying cervical spine involvement in rheumatoid arthritis (RA) remains unidentified. The purpose of the current study was to determine the in vivo cervical segmental motion in RA patients with atlantoaxial subluxation (AAS) using a patient-based three-dimensional magnetic resonance imaging (MRI) computer model.

METHODS

Healthy volunteers and RA patients with AAS (all females, n=10) underwent MRI examination of the cervical spine. Each vertebral body from the occipital bone (Oc) to the first thoracic vertebra (T1) was reconstructed from slices of T2-weighted sagittal MR images in the neutral, flexion, and extension positions. Using volume merge methods, each reconstructed vertebral body was virtually rotated and translated. Rotational segmental and translational segmental motions were obtained in three major planes.

RESULTS

Overall, the axial translational motions in the RA group were lower than those in the healthy volunteers; however the axial translational motion at only C1-C2 during flexion was at the same level as that in the healthy volunteers and was greater on the bottom side than that at other intervertebral levels. The frontal rotational motions at C1-C2 during extension were greater in the RA patients than those in the healthy volunteers (p<0.05).

CONCLUSION

The atlantoaxial joints in the RA patients with AAS showed great frontal rotational motion during extension and great axial translation on the bottom side during flexion. The current noninvasive MRI-based method could be useful in evaluating the 3-D dynamic mechanism underlying cervical involvement in RA in vivo.

[Clinical characteristics and diagnosis of rheumatoid arthritis of upper cervical spine: analysis of 71 cases]

OBJECTIVE

To study the clinical characteristics and diagnosis of rheumatoid arthritis (RA) in the upper cervical spine.

METHODS

The clinical data of 71 patients with RA in the upper cervical spine, 18 males and 53 females, aged 46.2 (23-76), with a mean duration of RA of 18.2 years (2 months-47 years) were retrospectively reviewed. Fifty-three patients received glucocorticoid for more than 3 months. In addition to routine examinations, all patients underwent plain X-ray film taking, CT and MRI scanning, and erythrocyte sedimentation rate, rheumatoid factor (RF) and antistreptolysin O testing.

RESULTS

The symptoms of upper cervical spine appeared at 8.3 years (2 months-46 years) after the diagnosis of RA was confirmed. The clinical manifestations of RA in the upper cervical spine were intractable pain in craniocervical junction or radiating pain. Abnormal postures in the neck and Sherp-Purser's sign were positive in some patients. Progressive neurological dysfunction with the involvement of spinal cord, medulla, or some cranial nerves might gradually appear. Irregular destruction of bone with osteoporosis around the lateral and median atlantoaxial joint was a common finding in the X-ray films and CT scans. Instability of the atlantoaxial joint, including anterior atlantoaxial subluxation, posterior atlantoaxial subluxation and anterior-posterior atlantoaxial subluxation were found in 68 cases, while rotation subluxation was presented in 37 cases. Vertical migration of the odontoid was seen in 11 cases. RF was positive in 18 cases. MRI revealed that the cause of spinal cord compression was the bone tissue and soft tissue pannus.

CONCLUSIONS

RA in the upper cervical spine is a common situation in the clinical settings. The key point in the diagnosis of this disease is the identification of instability in the atlantoaxial joint and assessment of the spinal neurological deficit. And a careful analysis of the natural history will further help to achieve a better treatment effect.

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.

[Rheumatoid arthritis with atlanto-axial subluxation. Pre-and postoperative symptoms, radiological findings and operative complications]

INTRODUCTION

The aim of the study was to study pre- and postoperative symptoms, radiological findings and operative complications in rheumatoid arthritis (RA) patients, operated in the atlantoaxial joint.

MATERIALS AND METHODS

A retrospective study of 31 RA patients (24 women, seven men) operated for anterior atlantoaxial subluxation (aAAS) at the Neurosurgical Department, Aarhus University Hospital, in the period of 1993-2003. Information was obtained retrospectively from the patients charge.

RESULTS

Mean age at RA debut was 38 years (16-69 yrs), and neck symptoms were seen after a mean time of 15 years (0-39 yrs) of illness. Radiological examination at this time showed irreversible atlantoaxial changes, and operation was performed within 0-9 years (mean 1.6 yrs). The patients were characterized by high disease activity: C-reactive protein, anaemia, positive IgM-rheumatoid factor (84%), and progressive radiological changes in the peripheral joints. All patients were treated with DMARDs (disease modifying anti rheumatic drugs). Neck pain (100%) and neurological symptoms/manifestations (87%) were seen preoperatively. After operation symptoms were relieved in 68% of the patients, while 22% were unchanged, and 10% had worsened. Postoperative complications included cardiac death, dislocation of the cervical spine, fracture of arcus atlantis, hemiparesis, dysphagia, bed sores and infection of the surgical scar (29%).

CONCLUSION

Neck symptoms were seen after 15 years of illness, and within the following 1.6 years patients were operated for aAAS. After the operation most of the patients (68%) had relief from symptoms, while 29% had postoperative complications, including cardiac death, dislocation of the cervical spine, fracture of arcus atlantis, hemiparesis, dysphagia, bed sores and infection in the surgical scar.

Upper cervical spine instability in pseudoachondroplasia

BACKGROUND

Pseudoachondroplasia (PSACH) is a rare autosomal dominant skeletal dysplasia associated with os odontoideum and atlantoaxial instability. This study aims to define the characteristics of upper cervical spine instability in patients with PSACH and analyze the relation between the incidence of upper cervical instability and os odontoideum.

METHODS

Fifteen patients (10 women and 5 men) with PSACH of Korean ethnicity with mean age of 23.7 years (range, 3-44 years) at presentation to our hospital with varied complaints, including short stature, limb deformity, neck pain, and neurological symptoms, were evaluated clinicoradiologically for upper cervical spine instability. The patients were separated into group 1 (n = 9) with os odontoideum and group 2 (n = 6) without os odontoideum. Comparisons were made using parameters such as instability index, rotational instability, atlantodens interval and space available for cord, and analysis done to correlate cervical instability with age and Japanese Orthopedic Association (JOA) score.

RESULTS

Significant differences were found statistically when the 2 groups were compared on the basis of the space available for the cord (SAC), JOA scoring, and rotational instability. Linear relationship was found between instability and age and JOA score. Incidence of os odontoideum was 60% in our study group.

CONCLUSIONS

Os odontoideum led to an increase in the incidence of upper cervical spine instability. Instability increased with the age. The presence of os odontoideum and atlantoaxial instability did not warrant for surgery because no signs of cervical myelopathy developed or progressed in our patients during the follow-up period, but these patients should undergo regular clinical and radiological evaluation.

LEVEL OF EVIDENCE

Level IV prognostic study.

Atlantoaxial rotatory fixation owing to neck burn

The purpose of this paper is to present a case of severe atlantoaxial rotatory fixation owing to a previously unreported etiology, and to discuss its pathogenesis and management. Conservative measures were unable to prevent progression, thus requiring surgical intervention.

Screw fixation via diploic bone paralleling to occiput table: anatomical analysis of a new technique and report of 11 cases

Several types of posterior approaches have been adopted for occipitocervical fusion. Prior to this study, Foerater et al. in 1927 used a fibular strut graft in the site between the occiput and the lower cervical spine to achieve fusion. Since then, various techniques including wrings, Hartshill loop, AO reconstructive plate, and AXIS occipital plate were described and used widely. As far as we know, all these techniques involve the screw placement vertical to the diploic bone; however none has ever addressed the feasibility of screw placement in occiput parallelling to the diploic bone. In our study, 30 dry specimens of human occiputs were measured manually using vernier calipers and protractors. The intradiploic screw was first supposed to be inserted inferiorly to the superior nuchal line (SNL) prominence. The entry point located at the superior edge of the SNL prominence. Afterward, the measurements of extracranial occiput in SNL area on midline and bilateral 15 mm to the midline saggital-cutting planes of the occiput were conducted. The thickness of the occipital bone at the location of SNL prominence, the entry point, the exit point and the screw orientation were measured, respectively. Afterward, 11 patients with craniocervical malformation were treated surgically using this alternative and their X-ray radiographs and CT scans were evaluated postoperatively. The data showed that the occipital at the site of SNL prominence was the thickest. The thickest point was external occipital protuberance (EOP), which was up to 14 mm. The thickness decreased gradually from the site of SNL to the superior border of surgical decompressed area. The actual length of screw channel was about 26 mm. The mean thickness for safe screw insertion ranged from 5.73 to 14.14 mm. A total of 22 intraocciput screws parallel to diploic bone were placed precisely, without injury to the cerebral and inner occipital venous sinus. The results confirm that occiput is available for holding intraocciput screw paralleling to diploic bone.

Comparison of Contemporary Occipitocervical Instrumentation Techniques with and Without C1 Lateral Mass Screws

Objective:

This study was designed to test the kinematic properties of three occiput-C2 instrumentation constructs with and without supplemental rigid C1 fixation. The results are compared with intact specimens and with constructs incorporating contemporary cabling techniques.

Methods:

Five unembalmed human cadaver specimens underwent range of motion (ROM) testing in the intact condition, followed by destabilization with odontoid osteotomy. Destabilized specimens then underwent ROM testing with each of seven occipitocervical instrumentation constructs, all incorporating occipital screws: C1 and C2 sublaminar cables with cable connectors, C2 pars screws +/− C1 lateral mass screws, C2 lamina screws +/− C1 lateral mass screws, and C1–C2 transarticular screws +/− C1 lateral mass screws.

Results:

All seven constructs demonstrated significantly lower ROM in all loading modes than intact specimens (P &lt; 0.05). With a single exception, the addition of C1 lateral mass screws to the screw-based constructs produced no significant change in ROM in any of the loading modes. Compared with intact specimens, constructs anchored by C1–C2 transarticular screws demonstrated the greatest decrease in ROM, and those anchored by sublaminar cables demonstrated the least decrease in ROM.

Conclusion:

Any of the tested screw-based constructs are likely to provide adequate support for the patient with an unstable craniocervical junction. Therefore, the choice of construct should be based on anatomic considerations. The routine incorporation of C1 lateral mass screws into occipitocervical instrumentation constructs does not seem necessary.

[Surgical treatment of craniocervical instability. Review paper]

The concept of spinal instability is still controversial. Anatomical, biomechanical, clinical and radiographic variants are involved and make the definition complicated. There are solid diagnostic bases in cases of fractures and degenerative disorders; however, pure spinal instability is still under study. The latter may be defined as increased mobility that goes beyond the physiological limits of one vertebra over another in at least one of the three spinal planes of motion. In the case of the craniocervical region, its understanding becomes even more challenging, since its anatomy and physiology are more complex and it is more mobile. Surgical treatment is possible with either an anterior or a posterior approach. Best results are obtained with occipitocervical or atlantoaxial stabilization through a posterior approach, since the anterior one has its limitations. For example, a transoral approach with a bone graft provides compression strength but does not enable immediate appropriate fixation and involves the risk of infection. The choice of the surgical approach must consider the patient's medical status, the specific spine levels involved, the extent of neurological compromise, the X-ray abnormalities and the individual pathology. The goals of surgery are achieved through an appropriate anatomical alignment, assuring the protection of the neural elements and achieving proper spine stabilization with as much preservation of the mobile vertebral segments as possible.

Efficacy of a C1-C2 self-sustained natural apophyseal glide (SNAG) in the management of cervicogenic headache

STUDY DESIGN

Randomized, double-blind, placebo controlled trial.

OBJECTIVES

To determine the effect of a C1-C2 self-sustained natural apophyseal glide (SNAG) on cervicogenic headache.

BACKGROUND

Cervicogenic headache is a common condition causing significant disability. Recent studies have shown a high incidence of C1-C2 dysfunction, evaluated by the flexion-rotation test (FRT), in subjects with cervicogenic headache. To manage this dysfunction, Mulligan has described a C1-C2 self-SNAG, though no studies have investigated the efficacy of this intervention approach.

METHODS

A sample of 32 subjects (mean _ SD age, 36 +/- 3 years) with cervicogenic headache and FRT limitation were randomized into a C1-C2 self-SNAG or placebo group. After an initial instruction and practice visit in the clinic, interventions consisted of exercises applied independently by the subject twice daily at home on a continual basis. FRT range was measured twice, before and immediately after the instruction and practice visit. Headache symptoms were determined by a headache index over time, assessed by questionnaire preintervention, at 4 weeks postintervention, and at 12 months postintervention.

RESULTS

No differences were found in baseline measures between groups. Immediately after the initial instruction and practice visit performed with the supervision of the therapist, FRT range increased by 15 degrees (SD, 9) for the C1-C2 self-SNAG group (P < .001), which was significantly more than 5 degrees (SD, 5) for the placebo intervention (P < .001). There was also a significant interaction for the variable headache index between group and time (P < .001), indicating that group difference was dependent on time. There was no difference in headache index scores at baseline between groups. Headache index scores were substantially less in the C1-C2 self-SNAG group (mean +/- SD points at 4 weeks, 31 +/- 9; mean +/- SD points at 12 months, 24 +/- 9) compared to the placebo group (mean +/- SD points at 4 weeks, 51 +/- 15; mean +/- SD points at 12 months, 44 +/- 13) at 4 weeks (P < .001) and 12 months (P < .001), with an overall (+/-SD) reduction of 54% (+/-17%) for the individuals in the C1-C2 self-SNAG group.

CONCLUSIONS

These results provide evidence for the efficacy of the C1-C2 self-SNAG technique in the management of individuals with cervicogenic headache.

Cervicomedullary compression secondary to massive calcium pyrophosphate crystal deposition in the atlantoaxial joint with intradural extension and vertebral artery encasement

BACKGROUND

Deposition of CPPD crystals occurs in the fibrous and hyaline cartilage of the joints and intervertebral disks of the spine. Half of patients known to have chondrocalcinosis had asymptomatic calcification in the odontoid region. The cases of 12 patients with a spinal cord syndrome secondary to CPPD deposition in the odontoid region were published in the literature. In all those cases, the mass lesion was extradural in location with good outcome after surgical decompression via the transoral route.

CASE DESCRIPTION

We report on a rare case of large periodontoid CPPD deposition causing cervicomedullary compression, erosion of the overlying bone, and underlying dura with intradural extension and vertebral artery encasement.

CONCLUSIONS

Calcium pyrophosphate dihydrate is a rare cause of cervicomedullary compression. Intradural extension of periodontoid CPPD has not been reported on.

Cervical spine range of motion in children with posterior occipitocervical arthrodesis

This prospective study compared cervical spine (c-spine) range of motion (ROM) in children with posterior occipitocervical arthrodesis to a control group of healthy participants. Cervical spine ROM is likely be altered after fusion. However, the extent to which posterior occipitocervical arthrodesis affects ROM in the c-spine of children has not yet been established. Furthermore, there are conflicting reports on this topic in the literature. To the best of our knowledge, no study has specifically addressed the effect of posterior occipitocervical arthrodesis on c-spine ROM in children. In this study, c-spine ROM of 15 patients who underwent posterior occipitocervical arthrodesis for upper c-spine instability was evaluated and compared with 15 healthy age-matched children. We used the CROM Goniometer (Performance Attainment Associates, St Paul, MN) to measure c-spine flexion, extension, lateral bending, and axial rotation. Student t test was used to evaluate the study results. Cervical spine ROM was significantly decreased in children with posterior occipitocervical arthrodesis compared with controls (P < 0.05). Axial rotation was the most affected movement, decreasing by an average of 30 degrees in each direction, flexion and extension each decreased by 13 degrees, and lateral bending decreased by approximately 7 degrees in each direction. Posterior occipitocervical arthrodesis decreases c-spine ROM in children compared with healthy controls.

The relationship of cervical joint position error to balance and eye movement disturbances in persistent whiplash

Cervical joint position error (JPE) has been used as a measure of cervical afferent input to detect disturbances in sensori-motor control as a possible contributor to a neck pain syndrome. This study aimed to investigate the relationship between cervical JPE, balance and eye movement control. It was of particular interest whether assessment of cervical JPE alone was sufficient to signal the presence of disturbances in the two other tests. One hundred subjects with persistent whiplash-associated disorders (WADs) and 40 healthy controls subjects were assessed on measures of cervical JPE, standing balance and the smooth pursuit neck torsion test (SPNT). The results indicated that over all subjects, significant but weak-to-moderate correlations existed between all comfortable stance balance tests and both the SPNT and rotation cervical JPE tests. A weak correlation was found between the SPNT and right rotation cervical JPE. An abnormal rotation cervical JPE score had a high positive prediction value (88%) but low sensitivity (60%) and specificity (54%) to determine abnormality in balance and or SPNT test. The results suggest that in patients with persistent WAD, it is not sufficient to measure JPE alone. All three measures are required to identify disturbances in the postural control system.

Biomechanical comparison of two new atlantoaxial fixation techniques with C1–2 transarticular screw–graft fixation

Object

Two new techniques for atlantoaxial fixation have been recently described. In one technique, C-2 intra-laminar screws are connected with C-1 lateral mass screws; in the second, C-1 and C-3 lateral mass screws are interconnected and C-2 is wired sublaminarly. Both techniques include a C1–2 interspinous graft. The authors compared these techniques with the gold-standard, interspinous graft–augmented C1–2 transarticular screw fixation and with a control C1–2 interspinous graft fixation procedure alone.

Methods

In six human cadaveric occiput–C4 specimens, nonconstraining 1.5-Nm pure moments were applied to induce flexion, extension, lateral bending, and axial rotation during which three-dimensional angular motion was measured optoelectronically. Each specimen was tested in the normal state, with graft alone (after odontoidectomy), and then in varying order after applying each construct with a rewired graft. All three constructs allowed significantly less angular motion at the C1–2 junction than the wired interspinous graft alone during lateral bending and axial rotation (p < 0.01, paired Student t-test) but not during flexion or extension. Transarticular screw fixation with an interspinous graft allowed less motion at the atlantoaxial junction than the two new constructs in several conditions. Differences were greater between the transarticular screw construct and the intralaminar screw construct than between the transarticular screw construct and the C1–3 lateral mass screw construct. During lateral bending and axial rotation, the C1–3 construct allowed less motion at the atlantoaxial junction than the intralaminar screw construct.

Conclusions

Biomechanically, the gold-standard C1–2 transarticular screw fixation outperformed the two new techniques during lateral bending and axial rotation. Wiring C-2 to C1–3 rods provided greater stability than C1–2 laminar screws, but it sacrificed C2–3 mobility. It is unknown whether the small differences observed biomechanically would lead to clinically relevant differences in fusion rates.

Fracture of the atlas through a synchondrosis of the anterior arch complicated by atlantoaxial rotatory fixation in a four-year-old child

Fracture of the atlas is rare in children. We report a case of fracture of the atlas through a synchondrosis of the anterior arch complicated by atlantoaxial rotatory fixation in a four-year-old girl.

Preoperative evaluation of extension capacity of the occipitoatlantoaxial complex in patients with rheumatoid arthritis: comparison between the Bellhouse test and a new method, hyomental distance ratio

BACKGROUND

The authors devised a new method, the hyomental distance ratio (HMDR), for preoperatively identifying patients with a reduced occipitoatlantoaxial extension capacity, which was defined as the ratio of the hyomental distance in head extension position to that in the neutral position. They compared the accuracy of the HMDR with that of the Bellhouse test in 40 patients with rheumatoid arthritis.

METHODS

Each patient wearing goggles on which a goniometer was mounted sat upright with the head in the neutral position and then extended the head maximally. The angle of the goggles and the hyomental distance were measured in the two head positions, and a lateral cervical radiograph was taken simultaneously. The Bellhouse angle was defined as a difference in the angles of the goggles between these positions.

RESULTS

Median values of the radiologic occipitoatlantoaxial extension angle and the Bellhouse angle were 11.2 degrees and 24.9 degrees , respectively. In 21 of 40 patients, the radiologic occipitoatlantoaxial extension angle was less than 12 degrees (reduced occipitoatlantoaxial extension capacity). In these patients, extension of the median angle of 16.4 degrees occurred at the subaxial regions and was greater than that of 8.5 degrees in patients with a radiologic occipitoatlantoaxial extension angle of 12 degrees or more (P < 0.01). As a result, a strong relation between the Bellhouse angle and radiologic occipitoatlantoaxial extension angle was not established (P < 0.01, r = 0.48). In contrast, the HMDR correlated well with the radiologic occipitoatlantoaxial extension angle (P < 0.0001, r = 0.88). The areas under the receiver operating characteristic curve of the Bellhouse test and the HMDR were 0.72 and 0.95, respectively.

CONCLUSIONS

The HMDR was a good predictor of a reduced occipitoatlantoaxial extension capacity in patients with rheumatoid arthritis, but the Bellhouse test was not a clinically reliable method.

[The biomechanical study of craniovertebral junction fixation with posterior transarticular screw]

OBJECTIVE

To evaluate the stability of biomechanics of occipitoatlantoaxial reconstruction with transarticular screw fixation.

METHODS

Twelve fresh human cadaveric occipitocervical spine specimens were mounted in a custom-designed, spine-testing machine that applied pure moments while recording the three-dimensional angular movement at occiput (Oc)-C(1) and C(1 - 2) segments. The specimens were tested under seven different conditions: the intact (intact group), the occipitoatlantoaxial instability (Destabilized group), fixation with Ti-cable plus bone graft group (cable + graf group), fixation with the transarticular fixation (CTS group), fixation with SUMMIT occitocervical spinal fixation system (SUMMIT group), fixation with transarticular screw plus bone graft (CTS + graf group), and fixation with SMMIT system and plus graft group (SUMMIT + graf group). The data obtained were statistically analyzed.

RESULTS

The CTS group reduced motion to well within the normal rang. In the Oc-C(1) segment, The CTS group and SUMMIT group allowed a very small rang of motion (ROM) and neutral zone (NZ) during lateral bending and axial rotation. The ROM and NZ during flexion and extension of the SUMMIT group, were significantly smaller than those of cable + graf group and CTS group (6.64 degrees +/- 0.59 degrees, 2.49 degrees +/- 0.26 degrees, 0.50 degrees +/- 0.03 degrees, 0.21 degrees +/- 0.01 degrees, 0.27 degrees +/- 0.07 degrees, 0.13 degrees +/- 0.01 degrees vs 10.01 degrees +/- 1.26 degrees, 3.80 degrees +/- 0.79 degrees, 7.93 degrees +/- 1.34 degrees, 3.18 degrees +/- 0.95 degrees, 9.54 degrees +/- 0.87 degrees, 5.93 degrees +/- 0.74 degrees, P < 0.05). In the C(1 - 2) segment, ROM and NZ in all directions of CTS group were smaller in rotation than SUMMIT group (1.64 degrees +/- 0.39 degrees, 0.61 degrees +/- 0.15 degrees, 0.14 degrees +/- 0.05 degrees, 0.02 degrees +/- 0.01 degrees, 0.32 degrees +/- 0.04 degrees, 0.08 degrees +/- 0.01 degrees, vs 0.21 degrees +/- 0.04 degrees, 0.07 degrees +/- 0.03 degrees, 0.21 degrees +/- 0.12 degrees, 0.10 degrees +/- 0.02 degrees, 2.92 degrees +/- 0.28 degrees, 1.27 degrees +/- 0.11 degrees, all P < 0.05). There was no significant difference in ROM and NZ in all directions between CTS + graf group and SUMMIT + Graf group (P > 0.05).

CONCLUSION

In vivo biomechanics studies show that posterior occipitocervical transarticular fixation has unique features in reconstructing dynamic stability of the occipitoatlantoaxis, especially in controlling stability of rotation and lateral flexion, thus ensuring successful fusion of the implanted bone and allowing for clinical use of the technique.

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 &lt; 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 &lt; 0.05). The C1-C2 angle was, on average, 9.3 degrees greater in the protrusion position than in the flat pillow position (P &lt; 0.05).

Conclusion

This study showed that the protrusion position using a flat pillow and a donut-shaped pillow during general anesthesia reduced the anterior atlantodental interval and increased the posterior atlantodental interval in RA patients with atlantoaxial subluxation. This suggests that the protrusion position, which involves support of the upper cervical spine and extension at the craniocervical junction, might be advantageous for these patients.

Posterior atlantoaxial three-point fixation: comparison of intraoperative performance between open and percutaneous techniques

INTRODUCTION

Atlantoaxial instabilities, which require surgical fixation follow a variety of clinical disorders. Different surgical procedures are used for stabilization of the atlantoaxial complex, mainly posterior wiring techniques and transarticular screw fixation. Nowadays, often a combination of transarticular screws and a posterior one-point fixation is used to achieve a three-point fixation, with superior biomechanical stability and good clinical results. Different modifications were developed to improve this technique. In 1995, a percutaneous approach for atlantoaxial stabilization was introduced. In clinical studies, the technique showed a tendency towards better outcome. Beside the outcome, the intraoperative performance is of special interest for minimal invasive approaches. We therefore compared the operation time, screw angulation and blood loss, between the open and percutaneous posterior atlantoaxial techniques.

MATERIALS AND METHODS

Two groups, each consisting of 17 patients, with either open (group 1) or percutaneous (group 2) atlantoxial stabilization, were compared. The operation time was retrospectively acquired from the patient's charts. The data for blood loss was provided by our anaesthesiological department, separated for intraoperative, postoperative and total blood loss. Screw angulation was measured on the postoperative x-ray by an orthopaedic surgeon.

RESULTS

The percutaneous group showed an average intraoperative blood loss of 239.7 ml, compared to 929.4 ml for the open group (p< or =0.001). The analogue values for the postoperative blood loss were 142.9 ml and 379.4 ml for group 2 and group 1, respectively (p=0.008). Consecutively, the total blood loss showed also a statistically significant difference (p< or =0.001). The operation time was significantly different (p< or =0.001), with average values of 175.3 min (group 1) and 110.6 min (group 2). Screw angulation showed a trend towards a steeper angulation in the percutaneous group with an average angle of 56.8 degrees , compared to 53.9 degrees (group 1), although this was not statistically significant (p=0.053).

CONCLUSION

The percutaneous technique for atlantoaxial stabilization with a three-point fixation has clear intraoperative benefits, with shorter operation time and reduced blood loss. A trend towards steeper screw angulation was found and shows at least equal feasibility for transarticular screw placement with the percutaneous technique, compared to the standard open approach.

Cervical spine surgery in patients with rheumatoid arthritis: longterm mortality and its determinants

OBJECTIVE

Atlantoaxial subluxation (AAS) is a frequent manifestation of rheumatoid arthritis (RA). The instability of the craniocervical junction caused by AAS is a potentially fatal condition and may require surgical treatment. Systemic manifestations associated with RA may increase the risk of perioperative complications. We evaluated the longterm mortality and its determinants in RA patients with AAS after cervical spine surgery.

METHODS

A retrospective study of consecutive patients treated at Kuopio University Hospital between 1994 and 1998. Preoperative risk factors, neurological impairment using the Ranawat classification, perioperative course, functional outcome, and survival status were evaluated.

RESULTS

During the study period 86 rheumatoid patients with AAS underwent cervical spine surgery. The mean followup time was 7.5 years (range 5.0-9.8). During the followup, 32 patients (37%) died. The mean survival time after surgery was 7.2 years (95% CI 6.7-8.0). Seven patients experienced postoperative complications. Age, AAS other than horizontal, and occurrence of complications were independent predictors of mortality. In two-thirds of the patients there was relief or decrease of pain, and the functional capacity improved. Neurological deficits subsided in 53% of cases.

CONCLUSION

Patients with RA should be actively studied for AAS or other cervical instability, even when cervical symptoms are minor. Attention should be paid to perioperative management of these patients. Surgical treatment may not decrease the mortality of patients with RA, but it may result in more symptom-free life-years.

Internal reduction established by occiput-C2 pedicle polyaxial screw stabilization in pediatric atlantoaxial rotatory fixation

Atlantoaxial rotatory fixation is an uncommon disorder of childhood, which can be treated conservatively when diagnosed early. Although spontaneous correction occasionally occurs, most of the patients usually benefit from collar or traction therapies. If there is no intervention or if all external therapeutic modalities fail, the deformity may become chronic and irreducible. In such rare cases, surgical correction and stabilization are needed to prevent future head and neck deformity or facial asymmetry. In this report we describe a novel surgical technique used in a pediatric case presenting with delayed type 2 atlantoaxial rotatory fixation, in whom all external reduction methods had failed. The patient's deformity was treated by occiput-C2 pedicle polyaxial screw stabilization. This technique is effective for reducing the atlantoaxial fixation in children.

AtlantoAxial Rotatory Fixation: Part 3—A Prospective Study of the Clinical Manifestation, Diagnosis, Management, and Outcome of Children with AlantoAxial Rotatory Fixation

OBJECTIVE:

This is a prospective study of the clinical manifestations, diagnostic motion analysis, management, and outcome of children with atlantoaxial rotatory fixation (AARF).

METHODS:

Fifty children presenting with painful torticollis were subjected to the three-head positions diagnostic computed tomographic scanning protocol described in Part II of our AARF study. Twenty-nine children qualified as having AARF (8 Type I, 11 Type II, and 10 Type III), and six children were classified in the diagnostic gray zone (DGZ). The AARF patients were given either halter or calipers traction depending on the type and chronicity of pretreatment delay. Upon reduction, patients were immobilized with either a cervicothoracic brace or a halo. Recurrence of AARF on halo and patients whose deformity was not reducible were given posterior C1C2 fusion at the best achievable alignment. The difficulty and results of treatment were measured according to the following: duration of traction, number of reduction slippage, percent not reducible by traction, percent needing halo, percent needing fusion, total duration of treatment, total number of treatment procedures, and percent who lost normal C1C2 dynamics. Results were compared between groups stratified by AARF types, by chronicity of pretreatment delay (acute ≪ 1 mo, subacute = 1–3 mo, chronic ≥ 3 mo) and by the presence or absence of recurrence (recurrent AARF defined as having two or more slippages). DGZ patients were treated with only comfort measures for 2 weeks and then restudied. Only those children with persistent symptoms and DGZ or worse motion dynamics were given traction and bracing.

RESULTS:

Neither age nor etiology significantly influenced the severity of AARF. There was only a slight tendency for children younger than 5 years, and for trauma, to associate with severe C1C2 interlock. Delay of treatment up to 11 months did not result in improvement of the neck restriction or in abatement of pain. In fact, there are strong suggestions that prolonged delay could lead to worsening of the rotatory dynamics: Type I AARF are highly correlated with delays longer than 3 months and Type III with delays less than 1 month. Also, four patients who had serial motion studies during the delay period showed clear worsening in the pathological stickiness in C1C2 rotation. In addition, chronic rotatory deformity led to progressive occiput −C1 separation or laxity teleologically to compensate for a skewed visual axis. The mean occiput −C1 separation angle for chronic patients was 31.2° versus 5° for acute patients and less than 3° for normal children. The difficulty and duration of treatment, the number of reslippage after reduction, the rate of irreducibility, the need for halo and fusion, and the percentile of patients ultimately loosing normal C1C2 rotation were significantly greater with Type I patients than Type III patients, with Type II patients being intermediate. Likewise, chronic patients of all AARF types were much worse in all parameters than acute patients; subacute patients were closer to chronic patients in complexity and outcome. Severity and chronicity exerted independent effects on outcome, and the worse identifiable subgroup were the chronic Type I patients versus the best subgroup of acute Type III patients.

Thirteen patients developed recurrent AARF; they had much worse prognosis in all aspects measured than nonrecurrent patients. Recurrence was adversely influenced by both the severity (type) and chronicity of AARF. Half of the DGZ patients resolved with analgesics, but two of six remained symptomatic and in DGZ dynamics, and one deteriorated to Type III AARF. Two of those three patients responded easily to traction and bracing, and one was lost to follow-up.

CONCLUSION:

Children with painful torticollis should be subjected to the three-position computed tomographic diagnostic protocol, not only to secure the diagnosis of AARF but also to grade the severity of the condition by virtue of the dynamic motion curve. Closed reduction with traction should be instituted immediately to avoid the serious consequences of chronic AARF. Proper typing and reckoning of the pretreatment delay are requisites for selecting treatment modalities. Recurrent dislocation and incomplete reduction should be treated with posterior C1C2 fusion in the best achievable alignment. Open reduction and halo immobilization to avoid permanent fixation can be tried with select cases.