Congenital arthrogryposis associated with atlantoaxial subluxation and dysraphic abnormalities. Case report

The authors report the case of a 27-year-old woman with an arthrogryposis multiplex congenita (AMC) associated with atlantoaxial subluxation. To the authors' knowledge, this is the first report of its kind. The authors review the literature with reference to dysraphic abnormalities associated with atlantoaxial subluxation and with AMC. The patient presented with severe tetraparesis following a minor traffic accident. She underwent a procedure in which transoral decompression and dorsal stabilization were performed and, postoperatively, made a good clinical outcome. The authors stress the need for diagnostic neuroimaging of the craniocervical junction in patients with AMC.

Analytical static stress analysis of first cervical vertebra (atlas)

INTRODUCTION

Fracture of the atlas was first described by Jefferson (1920). He theorised a bursting mechanism of fracture as the occipital condyles were driven into the atlas. Experimental studies by Hays and Alker (1988) and Panjabi et al (1991) were also conducted to explain the injury mechanisms. Injury mechanisms and fracture patterns are important in the clinical evaluation of spinal injuries. Recognition and interpretation of the fracture patterns help to determine the spinal instability and consequently the choice of treatment. Although the fracture mechanics of the atlas have received much attention, it has not been investigated using theoretical modelling.

MATERIALS AND METHODS

A high-definition digitiser was used to obtain the geometrical data for the finite element mesh generation. Contrary to the widely used method, such as computed tomography scan for geometric extraction, the direct digitising process of the dried specimen reliably preserves the accurate topography of up to 0.1-mm interval of the original structure. The finite element model was exercised under an axial compressive mode of pressure loading to investigate the sites of failure reported in vivo and in vitro.

RESULTS

Using material properties from literature, the predicted results from the 7808-finite element model demonstrate high concentration of localised stress at the anterior and posterior arch of the atlas, which agrees well with those reported in the literature. Furthermore, our results are also in good agreement with the findings reported by Panjabi et al (1991), which show that the groove of the posterior arch is subjected to enormous bending moment under simulated hyperextension conditions.

CONCLUSIONS

The close agreement of the failure location provided confidence to perform further analysis and in vitro experiments. The predicted results from finite element analysis may be potentially used to supplement experimental research in understanding the clinical biomechanics of the C1.

Atlantal stenosis: a rare cause of quadriparesis in a child. Case report

The authors report the case of a 3-year-old boy who suffered from quadriparesis and respiratory distress after failing to execute a somersault properly. Neuroimaging revealed spinal cord contusion with marked spinal canal stenosis at the level of the atlas. No subtle instability, occult fracture, or other congenital abnormalities were confirmed. Spinal cord contusion with marked canal stenosis is rare, and only several adult cases have been reported. Severe stenosis at the level of the atlas may predispose individuals to severe spinal cord contusion, as occurred in our patient after sustaining trivial trauma.

Pediatric atlas fracture: a case of fracture through a synchondrosis and review of the literature

OBJECTIVE AND IMPORTANCE

Although uncommon, atlas fractures occur in the pediatric population. We present an illustrative case of a patient with a fracture through a synchondrosis of the atlas, and we review previous reports of pediatric first cervical vertebral fractures. The clinical and radiographic findings are described. In addition, we describe the use of magnetic resonance imaging in characterizing a pediatric atlas fracture.

CLINICAL PRESENTATION

A 6-year-old boy who fell from a tree onto his vertex presented with neck pain, cervical muscle spasm, and head tilt. Computed tomographic and magnetic resonance imaging studies demonstrated a fracture through a left anterior synchondrosis with surrounding edema. In the literature, 10 cases of pediatric atlas fracture have been reported.

INTERVENTION

Treatment of pediatric atlas fractures consists of rigid bracing such as a Minerva jacket. All of the cases of isolated C1 fracture in children, except the patient originally described by Sir Geoffrey Jefferson, survived and recovered with full function. Surgery is rarely indicated for isolated atlas fractures.

CONCLUSION

The classic clinical presentation, combined with an appropriate injury scenario, should alert the clinician to the possibility of a pediatric atlas fracture and should prompt rapid evaluation with imaging studies to establish a diagnosis. When the injury is appropriately diagnosed and treated, an excellent outcome can be expected.

Unilateral osseous bridging between the arches of atlas and axis after trauma

STUDY DESIGN

This is a case report.

OBJECTIVE

To present a case of osseous bridging between C1 and C2 of posttraumatic origin and with an associated closed head injury and to discuss its pathogenesis and clinical outcome after surgical resection.

SUMMARY OF BACKGROUND DATA

Heterotopic ossifications of posttraumatic origin in the spine are rare. To the authors' knowledge, no cases have been reported of spontaneous bony bridging between C1 and C2 with a posttraumatic origin.

METHODS

Heterotopic ossifications were detected when pain and limited axial rotation (left/right 10 degrees/0 degree/20 degrees) were persistent, despite intensive physical therapy. Because heterotopic ossifications were ankylosing C1 and C2, the decision was to resect the osseous bridge in combination with a careful mobilization of the cervical spine. Functional computed tomography was performed for analysis of the postoperative results.

RESULTS

Four months after surgery, clinical examination showed asymptomatic increased axial rotation. Functional computed tomography indicated that left C1-C2 axial rotation was reduced, possibly related to impingement caused by residual bony spurs. Pathologic changes in the surrounding soft tissue may be another important factor in the persistent limitation of rotation.

CONCLUSIONS

Osseous bridging between C1 and C2 may be considered when persistent pain and limited axial rotation are observed after trauma. Operative resection, together with careful intraoperative and postoperative mobilization, may be the treatment of choice.

Complex atlantoaxial fractures

OBJECT

The authors conducted a retrospective study to evaluate the treatment of complex C1-2 fractures.

METHODS

There were 10 cases of complex C1-2 fractures. Six patients were men (median age 58 years) and four patients were women (median age 55.5 years). Injuries resulted from seven falls, two motor vehicle accidents, and one diving incident. Three patients suffered from upper-extremity weakness. Neurological function in seven patients was intact preoperatively. Fracture combinations included six Jefferson/Type II odontoid, two anterior ring/Type II odontoid, one posterior ring/Type II odontoid, and one posterior ring/Type III odontoid/Type III hangman's fracture. All patients underwent surgery, five after halo immobilization for an average of 4 months failed to provide stability. Treatment included placement of six odontoid screws, one posterior C1-2 transarticular screw, one odontoid screw with anterior C1-2 transarticular screw fixation, one C1-2 transarticular screw with C1-2 Songer cable fusion, and one odontoid screw with bilateral C-2 pedicle screw fixation. Specific treatment was determined by the combination of fractures. Postoperatively, all patients were immobilized in a hard collar for 3 months. There were no intraoperative surgery-related complications. The mean follow-up period was 28.5 months. Neurological recovery was observed in one of three patients who presented with neurological deficits. Fusion occurred in all cases.

CONCLUSIONS

The goals in treating these complex fractures are to achieve early maximum stability and minimum reduction in range of motion. These are often competing phenomena. Frequently in cases of atlas-axis fracture, odontoid screw fixation combined with hard collar immobilization is the best therapy, provided the transverse atlantal ligament is competent. If not, C1-2 stabilization with placement of transarticular screws is required for best results.

Gunshot wound of the atlas in a youth

The case of a bullet retained, without causing neurological symptoms, in the anterior arch of a youth's atlas after a gun had been fired a short distance from his mouth is reported. The patient was managed with external stabilization.

[Atlas fractures]

Fractures of the atlas account for 1-2% of all vertebral fractures. We divide atlas fractures into 5 groups: isolated fractures of the anterior arch of the atlas, isolated fractures of the posterior arch, combined fractures of the anterior and posterior arch (so-called Jefferson fractures), isolated fractures of the lateral mass and fractures of the transverse process. Isolated fractures of the anterior or posterior arch are benign and are treated conservatively with a soft collar until the neck pain has disappeared. Jefferson fractures are divided into stable and unstable fracture depending on the integrity of the transverse ligament. Stable Jefferson fractures are treated conservatively with good outcome while unstable Jefferson fractures are probably best treated operatively with a posterior atlanto-axial or occipito-axial stabilization and fusion. The authors preferred treatment modality is the immediate open reduction of the dislocated lateral masses combined with a stabilization in the reduced position using a transarticular screw fixation C1/C2 according to Magerl. This has the advantage of saving the atlanto-occipital joints and offering an immediate stability which makes immobilization in an halo or Minerva cast superfluous. In late instabilities C1/2 with incongruency of the lateral masses occurring after primary conservative treatment, an occipito-cervical fusion is indicated. Isolated fractures of the lateral masses are very rare and may, if the lateral mass is totally destroyed, be a reason for an occipito-cervical fusion. Fractures of the transverse processes may be the cause for a thrombosis of the vertebral artery. No treatment is necessary for the fracture itself.

Cervical trauma: rationale for selecting the appropriate fusion technique

The selection of the appropriate surgical approach in the management of an unstable cervical spine injury is predicated on the biomechanic deficiencies of the bony and ligamentous structures, the age of the patient, the level of experience of the surgeon, and the concomitant medical comorbidities. The optimal approach ideally is the least invasive, provides the greatest benefit-to-risk ratio in terms of potential injury to contiguous neurovascular structures, and provides adequate stabilization to avoid cumbersome external immobilization and allows early rehabilitation. This article discusses anterior, posterior, and combined stabilization techniques in patients who have sustained trauma to the upper and lower cervical spine.

Treatment of stable burst fracture of the atlas (Jefferson fracture) with rigid cervical collar

STUDY DESIGN

A retrospective review of a clinical series.

OBJECTIVE

To evaluate the use of a rigid cervical collar alone as the treatment for stable Jefferson fracture, and to devise an algorithm for treatment of Jefferson fracture with or without an associated cervical injury.

SUMMARY OF BACKGROUND DATA

The traditional treatment for Jefferson fracture, if there is no indication for surgery, is immobilization by halo vest. Because halo vest placement is associated with intracranial infection and a significant degree of patient discomfort, slightly less rigid forms of external immobilization may be useful for the treatment of stable Jefferson fractures. No standard protocol calling for the use of one form of stabilization device has been reported.

MATERIALS

The medical records and radiographs of 16 consecutive patients with Jefferson fracture during a 2-year period were reviewed. Each patient underwent a complete cervical radiograph series and a computed tomographic scan. The mean C1 lateral mass displacement was 1.8 mm. Cervical spine radiographs, including lateral flexion-extension views were obtained 10 to 12 weeks after injury before the removal of an external immobilization device.

RESULTS

Of these 16 patients, 1 sustained a complete injury, and 7 sustained an incomplete injury. Eight patients were neurologically intact. Twelve patients sustained a stable Jefferson fracture and were treated with a rigid cervical collar (Miami-J collar [Jerome Medical, Moorestown, NJ]) alone from 10 to 12 weeks. The patient sustaining the complete neurologic injury died of multisystem trauma. All 15 live patients showed no instability on their follow-up plain radiographs before the removal of an external stabilization device. Six patients underwent further plain radiographs approximately 1 year after the fracture and similarly demonstrated no instability.

CONCLUSIONS

Isolated stable burst fracture of the atlas can be treated effectively with a rigid cervical collar alone for 10 to 12 weeks with good neurologic recovery and segmental stability. Unstable Jefferson fractures with concurrent unstable fracture of other cervical vertebrae, especially C2, requires surgical stabilization.

A biomechanical study of Jefferson fractures

STUDY DESIGN

Fifteen specimens of the first cervical vertebra were tested by the application of pure tensile forces to failure. Seven specimens had intact transverse ligaments, and eight had transection of the transverse ligament before testing. Specimens were tested to failure by the rapid application of laterally directed tensile force to the ring; this force then was exerted through the lateral masses to simulate the mechanism of injury for this fracture as proposed by Jefferson.

OBJECTIVES

To measure the biomechanical characteristics of the C1 ring, including the fracture patterns created with tensile loading, and to describe the influence of the transverse ligament on the behavior of the ring as it failed under tension.

SUMMARY OF BACKGROUND DATA

Jefferson fractures have been reproduced in the laboratory by subjecting head and neck preparations to axial load. However, no previous detailed biomechanical studies of the fracture characteristics of the isolated C1 vertebra have been reported.

METHODS

Specimens were tested to failure by rapid application of laterally directed tensile forces to the ring.

RESULTS

Eleven two-part and three three-part fractures occurred. The mean tensile strength of the atlas was found to be 2,280 N. The average deformation required to fracture the C1 ring was 1.57 mm. The total energy absorbed by the ring averaged 1.99 N-m. There was no statistically difference between those specimens with the transverse ligament intact and those without a transverse ligament.

CONCLUSIONS

The results of this study show that fractures of the C1 ring of greater than two parts can occur with pure tensile loading. The ring will fracture with as little as 1 mm of deformation.

Fractured cervical spine and aortic transection

A 17-year-old victim of a road traffic accident presented. Following investigation diagnoses of fractured first cervical vertebra, aortic transection, diffuse cerebral oedema, fractured right ribs 2-4 and pubic rami were made. Management of this case presented a number of anaesthetic dilemmas: management of the airway, use of cross-clamp vs. shunting or heparinization and bypass, cardiovascular and neurological monitoring, maintenance of cardiovascular stability during and post cross-clamp, minimizing the risk of post-operative renal and neurological dysfunction.

[Fracture of the odontoid process in primary myelopathy. Report of a case]

Fractures of the odontoid are reported to contribute in 15% to cervical spine fractures. The clinical findings range between no symptoms at all and sudden death. Neurological deficits are seen in 6 to 25% of these patients. The overall mortality in this group is 3 to 8%. Fractures of the odontoid process combined with primary myelopathy has been reported seldom. We describe a traumatic fracture of the odontoid process with primary myelopathy, the chosen therapy and the follow-up.

Unilateral posterior atlantoaxial transarticular screw fixation

Bilateral posterior C 1-2 transfacet screw placement with associated posterior bone graft wiring is the accepted treatment for patients with atlantoaxial instability. This technique was modified to treat 19 patients with atlantoaxial instability and unilateral anomalies that prevented placement of a screw across the C1-2 facet. In these cases, a single contralateral transarticular screw was placed in conjunction with interspinous bone graft wiring to avoid neural or vertebral artery injury and to provide C1-2 stability. Postoperatively, all 19 patients were placed in Philadelphia collars (mean immobilization 8 weeks, range 6-12 weeks). Unilateral C1-2 facet screw fixation was needed for the following reasons: a high-riding transverse foramen of the C-2 vertebra present in 13 patients (left side in eight, right side in five), poor screw purchase in two (left side in both), screw malposition in one (left side), severe degenerative arthritis in one (right side), neurofibroma in one (right side), and fracture of the C-1 lateral mass in one (left side). Six weeks postsurgery, one patient presented with a broken screw and required occipitocervical fusion with a Steinmann pin and wire cable from the occiput to C-3 to achieve solid fusion. Solid fusions were achieved in the other 18 patients (mean follow-up period 31 months, range 14-54 months); there was no delayed screw breakage, wire breakage, or spinal instability. There were no operative or postoperative neurological or vascular complications. The authors' experience demonstrates that unilateral C1-2 facet screw fixation with interspinous bone graft wiring is an excellent alternative in the treatment of atlantoaxial instability when bilateral screw fixation is contraindicated.

Cervical spine trauma. What is new?

To a large extent, what is new in cervical spine trauma relates to evolving indications for the use of various imaging modalities and expanded understanding of conditions that may influence traumatic sequelae. The American College of Radiology Appropriateness Criteria now provide guidelines for decisions concerning imaging in various clinical situations. This article reviews many of the publications of the past 6 to 7 years that may contribute to a radiologist's understanding of cervical spine injuries.

[Abnormality as differential diagnosis in atlas fracture]

In some patients, suspected fractures of the cranial part of the cervical spine are difficult to diagnose properly without the use of computed tomography or MT. In addition to imaging and positioning problems, the possibility of anomalies of the atlas vertebra may complicate the diagnostic considerations. Proper knowledge of such anomalies may facilitate the diagnostic procedures. The diagnostic problems are discussed, and are illustrated through two patients recently examined in our department.

[A case of atlanto-axial rotatory fixation associated with Jefferson's fracture]

The authors present a case of atlanto-axial rotatory fixation associated with Jefferson's fracture. A 52-year-old man was admitted to our hospital complaining of severe neck pain and torticollis after a traffic accident. Cervical x-ray films showed fracture of the atlas. CT scans demonstrated traumatic subarachnoid hemorrhage and atlanto-axial rotatory fixation. The patient was managed with skull traction and reposition was achieved. Although he was maintained in a halo device for 4 months, rotary fixation recurred. He underwent posterior fusion between the atlas and axis. We review the literature and discuss the diagnostic problems and methods of treatment for atlanto-axial rotatory fixation.

Craniocervical bone pneumatisation

We report a case of extensive craniocervical bone pneumatisation presenting after minor trauma. The patient had neurological signs and initial radiographs showed multiple lucencies in the skull base and the atlas vertebra. CT established the true nature of this rare condition.

Injuries involving the transverse atlantal ligament: classification and treatment guidelines based upon experience with 39 injuries

Comprehensive anatomic and clinical analyses of 39 patients with injuries involving the transverse atlantal ligament or its osseous insertions were performed to assess the morphology of the injured ligaments and the patients' capacity to heal. Injuries of the upper cervical spine were screened with plain radiographs, thin-section computed tomography, and magnetic resonance imaging studies. The injuries were classified as disruptions of the substance of the ligament (Type I injuries, n = 16) or as fractures and avulsions involving the tubercle for insertion of the transverse ligament on the C1 lateral mass (Type II injuries, n = 23). These two types of injuries had distinctly different clinical characteristics that were useful for determining treatment. Type I injuries were incapable of healing satisfactorily without internal fixation; they should be treated with early surgery. Type II injuries, which rendered the transverse ligament physiologically incompetent even though the ligament substance was not torn, should be treated initially with a rigid cervical orthosis, because they had a 74% success rate nonoperatively. Surgery should be reserved for patients with Type II injuries that have nonunion with persistent instability after 3 to 4 months of immobilization. Type II injuries had a 26% rate of failure of immobilization; therefore, close monitoring is needed to detect patients who will require delayed operative intervention.