Vertical atlantoaxial dislocation

Rare improperly treated traumatic vertical atlantoaxial dislocation: A case report and literature review

BACKGROUND

Because of the severity and fatal outcome of traumatic vertical atlantoaxial dislocation (AAD), most patients may die in the early post-traumatic period. The post-injury management of patients with vertical AAD has been rarely reported. Improper treatment may lead to disastrous outcome and further aggravate the neurologic symptoms.

CASE PRESENTATION

This report describes the perioperative management and outcome of a rare improperly treated patient with traumatic vertical AAD. The severe pulmonary infection of this patient prevented further surgery for vertical AAD. After placement of a halo vest, combined with effective antibiotic drug treatment, the patient's pulmonary infection was brought under control. The patient underwent atlantoaxial fusion using C1 lateral mass screws and C2 pedicle screws with the assistance of the halo vest. A computed tomography scan at 1 year follow-up indicated that the bone graft was fused and the patient was able to walk independently.

CONCLUSION

Skull traction is contraindicated in patients with traumatic vertical AAD. Application of a halo vest can be used for temporary fixation of the cervical spine and atlantoaxial fixation should be performed to maintain the stability of atlantoaxial articulation.

Transarticular Screw Fixation in the Treatment of Severe C1-C2 Dislocation: A Case Series Report

Background

To aim of the present paper was to evaluate the results of halo traction and transarticular screw fixation combined with bone autoplasty in patients with severe atlantoaxial dislocation.

Case presentation

This is a retrospective study of severe cases of atlantoaxial dislocation in nine patients (six men and three women) treated with preoperative halo traction and posterior C1–C2 transarticular screw fixation combined with bone autoplasty from June 2006 to June 2011 at the Saint Paul Hospital (Hanoi). The mean age of patients was 37.48 ± 13.753 years (range, 26–50 years). The possibility of fixing dislocation using a halo apparatus was investigated through a series of preoperative halo corrections performed within a span of 1–2 weeks. For transarticular screw fixation, two transarticular screws were used that were positioned according to the Magerl technique. For bone autoplasty, an iliac crest bone graft approximately 3 × 2 cm in size was used. The postoperative assessment of clinical improvement was performed using the neck disability index (NDI), the American Spinal Injury Association (ASIA) impairment scale, and the visual analog scale (VAS) measurement instruments, through the gradation of atlantoaxial dislocation, and via the clivoaxial angle(CAA) index and the space available for cord (SAC) index after 6 months. The image diagnosis demonstrates that all the cases of atlantoaxial dislocations are unstable and correspond to the Fielding and Hawkins type III dislocation. Eight patients underwent complete reduction using the halo fixation device. In one patient, the C1–C2 displacement was manually reduced during surgery. CT scanning revealed that the accuracy of screw placement was 94.4%. The bone fusion rate was 100% after 6 months. Based on the ASIA impairment scale, the preoperative examination of patients revealed grade C injuries in seven patients and grade D injuries in two patients. After surgery, all patients had grade D injuries. Six months after surgery, four patients had moderate self‐reported neck disability (30%–48%) and five patients reported mild disability (10%–28%); that is, the patient perception of the neck problem improved. In the postoperative phase, all patients showed an improvement in VAS pain scores and the SAC score returned to the normal range in all patients. The CAA returned to normal in only seven patients; in the other two patients, the CAA returned to a value that was close to normal (145° and 149°).

Conclusion

Through halo traction combined with transarticular screw fixation and bone autoplasty, noticeable postoperative improvements were attained based on the clinical scores for NDI, ASIA, and VAS, as well as SAC and CAA.

Traumatic injuries to the craniovertebral junction: a review of rare events

The craniovertebral junction is a specific region of the spine with unique anatomical and biomechanical properties that yields a wide variety of injury patterns. Junctional traumatic fractures and/or dislocations are widely reported in clinical practice, but we could identify only a subgroup of upper cervical spine traumatic injuries with very few cases reported in the literature, and for this reason may be considered rare. In some of these cases, the absence of spinal biomechanical instability, in association with moderate clinical symptoms (neck stiffness and pain) and the difficulty in fracture identification through standard cervical radiographs, leads to a high percentage of missed injuries. In other cases, traumatic events have been commonly described only in autopsy series due to the high degree of spinal biomechanical instability. Herein, we have summarized all the relevant literature concerning this issue and also included our cases, with the aim of emphasizing prompt diagnosis and correct management. We provide a guide for correctly identifying "rare" craniovertebral junction traumatic injuries.

Trauma of the upper cervical spine: focus on vertical atlantoaxial dislocation

PURPOSE

Traumatic ligament injuries of the craniovertebral junction, either isolated or associated with bone avulsion or fracture, often lead to death. These injuries are rare and underrated but are increasingly seen in emergency departments due to the improvement in initial on-scene management of accidents. Vertical atlantoaxial dislocation (AAD) is a specific lesion that was barely reported. Based on our experience, our goal was to systematically investigate the prevalence and prognosis of traumatic vertical AAD and discuss its management.

METHODS

All cervical CT scans performed at our institution between 2006 and 2010 for cervical trauma in adults were retrospectively reviewed. Based on the measurement of lateral mass index (LMI), defined as the gap between C1 and C2 articular facets, we identified three cases of traumatic vertical AAD in 300 CT scans. Their medical records were investigated.

RESULTS

The incidence of vertical AAD was 1% in the exposed population. One case was an isolated vertical AAD and two were associated with a type II odontoid fracture. We report the first case in the literature of unilateral vertical AAD. Two patients died rapidly; the survivor was treated with occipitocervical fixation. Specific maneuvers were used for immobilization and reduction.

CONCLUSIONS

This study found a not insignificant incidence of vertical AAD and a high lethality rate. LMI appears to be a relevant radiological criterion for this diagnosis, for which traction is contraindicated. Associated neurological or vascular damage should be suspected and investigated. In our experience, spinal surgical fixation is required because of major instability.

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.

Traumatic vertical atlantoaxial dislocation

We present a case of traumatic vertical atlantoaxial dislocation of 16 millimetres with a fatal outcome. We hypothesize that this extremely rare traumatic vertical atlantoaxial dislocation results from insufficiency of the C1/C2 facet capsules after rupture of the tectorial membrane and the alar ligaments.

Vertical atlantoaxial distraction injuries: radiological criteria and clinical implications

OBJECT

The authors sought to establish radiological criteria for the diagnosis of C1-2 vertical distraction injuries.

METHODS

Conventional radiography, computerized tomography (CT), and magnetic resonance (MR) imaging findings in five patients with a C1-2 vertical distraction injury were correlated with their clinical history, operative findings, and autopsy findings. The basion-dens interval (BDI) and the C-1 and C-2 lateral mass interval (LMI) were measured in 93 control patients who underwent CT angiography; these measurements were used to define the normal BDI and LMI. The MR imaging results obtained in 30 healthy individuals were used to characterize the normal signal intensity of the C1-2 joint. The MR imaging results were compared with MR images obtained in five patients with distraction injuries. In the 93 patients, the BDI averaged 4.7 mm (standard deviation [SD] 1.7 mm, range 0.6-9 mm) and the LMI averaged 1.7 mm (SD 0.48 mm, range 0.7-3.3 mm). Based on CT scanning in the five patients with distraction injuries, the BDIs (mean 11.9 mm, SD 3.2 mm; p < 0.001) and LMIs (mean 5.5 mm, SD 2 mm; p < 0.0001) were significantly greater than in the control group. Fast-spin echo inversion-recovery MR images obtained in these five patients revealed markedly increased signal distributed throughout the C1-2 lateral mass articulations bilaterally.

CONCLUSIONS

In 95% of healthy individuals, the LMI ranged between 0.7 and 2.6 mm. An LMI greater than 2.6 mm indicates the possibility of a distraction injury, which can be confirmed using MR imaging. Patients with a suspected C1-2 distraction injury may be candidates for surgical fusion of C1-2.