Athletic cervical spine injury in the setting of fusion failure of the anterior and posterior atlas.

This article describes a rare congenital abnormality of anterior and posterior C1 fusion failure presenting after an acute athletic injury to the fibrous nonunion. C1 congenital malformations are rare, occurring in approximately 2% of patients; even rarer are combined anterior and posterior arch malformations in the same patient. Posterior ring abnormalities are more common than anterior ring injuries (4.5:1, respectively). To the authors' knowledge, combined anterior and posterior ring congenital malformations with subsequent injury have not been previously described. In the current patient, a congenital failure of fusion of the anterior and posterior arches of C1 was identified. The anterior fibrous nonunion was injured while the patient played football, leading to transient neurologic injury and dysphagia from soft tissue swelling. The patient was initially diagnosed with an acute fracture at another facility; however, given advanced imaging, flexion and extension views, and a normal neurologic examination, the authors diagnosed a traumatized congenital defect. The injury healed with a short period of cervical collar immobilization and supportive measures. Such malformations are usually found incidentally, but they can be symptomatic after trauma. Images to distinguish these deficits can be difficult because the differences between chronic nonunions and congenital malformations are subtle. Surgery is rarely indicated for congenital malformations because they are often stable even after injury; however, they may predispose patients to neurologic injury in the future with high-risk activities. Because the current patient had an increased chance of future injury secondary to the lack of bone formation in the C1 vertebrae, he was restricted from participating in contact sports.

A novel radiographic targeting guide for percutaneous placement of transfacet screws in the cervical spine with limited fluoroscopy: A cadaveric feasibility study.

BACKGROUND: We describe a technique for percutaneous transfacet screw placement in the cervical spine without the need for lateral-view fluoroscopy. METHODS: Previously established articular pillar morphometry was used to define the ideal trajectory for transfacet screw placement in the subaxial cervical spine. A unique targeting guide was developed to allow placement of Kirschner wires across the facet joint at 90° without the guidance of lateral-view fluoroscopy. Kirschner wires and cannulated screws were placed percutaneously in 7 cadaveric specimens. Placement of instrumentation was performed entirely under modified anteroposterior-view fluoroscopy. All specimens were assessed for acceptable screw placement by 2 fellowship-trained orthopaedic spine surgeons using computed tomography. Open dissection was used to confirm radiographic interpretation. Acceptable placement was defined as a screw crossing the facet joint, achieving purchase in the inferior and superior articular processes, and not violating critical structures. Malposition was defined as a violation of the transverse foramen, spinal canal, or nerve root or inadequate fixation. RESULTS: A total of 48 screws were placed. Placement of 45 screws was acceptable. The 3 instances of screw malposition included a facet fracture, a facet distraction, and a C6-7 screw contacting the C7 nerve root in a specimen with a small C7 superior articular process. CONCLUSIONS: Our data show that with the appropriate radiographic technique and a targeting guide, percutaneous transfacet screws can be safely placed at C3-7 without the need for lateral-view fluoroscopy during the targeting phase. Because of the variable morphometry of the C7 lateral mass, however, care must be taken when placing a transfacet screw at C6-7. CLINICAL RELEVANCE: This study describes a technique that has the potential to provide a less invasive strategy for posterior instrumentation of the cervical spine. Further investigation is needed before this technique can be applied clinically.

Successful treatment of thoracolumbar fractures with short-segment pedicle instrumentation.

STUDY DESIGN: Retrospective radiographic review. OBJECTIVE: To determine whether clinical factors or common classification systems can predict the radiologic outcome of short-segment thoracolumbar fracture fixation. SUMMARY OF BACKGROUND DATA: Previous reports have indicated that short-segment thoracolumbar fracture fixation might not be appropriate for highly comminuted fractures or for patients with multiple traumatic injuries. METHODS: We conducted a retrospective radiographic review of 46 thoracolumbar fractures treated with short-segment posterior instrumentation to determine the rate of correction loss and instrumentation failure in relation to the Load Sharing Classification of Spine Fracture system and the AO Classification of Fractures system. No postoperative bracing was used. Patients with multisystem organ trauma and those with isolated injuries were included. RESULTS: An average loss of correction of 7.5 degree was observed. Pedicle screw placement into the fractured vertebra seemed to protect against correction loss: 4 of the 7 patients (57%) in the no intermediate fixation group had >10 degree loss of correction. No relationship was shown between loss of correction and Load Sharing Classification (< or = 6 or > or = 7 points), loss of correction and AO Classification, or loss of correction and level of injury (thoracolumbar junction vs. lower lumbar). CONCLUSIONS: With modern instrumentation and techniques, short-segment thoracolumbar fracture fixation could be used successfully, despite highly comminuted injuries, without anterior column support or supplemental bracing.