Laminar screw fixation in the subaxial cervical spine: A report on three cases

Morphological Evaluation of the Subaxial Cervical Spine in Patients with Basilar Invagination: A CT-based Study

STUDY DESIGN

Retrospective study.

OBJECTIVE

To evaluate the morphologic features of the subaixal cervical spine in patients with basilar invagination (BI) and provide information for the accurate screw placement in this region.

SUMMARY OF BACKGROUND DATA

BI is a congenital anomaly, comprising a wide range of abnormal structures. The screw fixation can be required in situation that BI is combined with subaxial cervical spine pathologies. However, there are no literatures specifically addressed the subaxial cervical morphology of BI.

METHOD

A total of 42 BI patients were included in this retrospective study. Forty-two patients without head or cervical disease were matched for sexes and ages. Information on radiographic features of the subaxial cervical spine was collected and compared systematically.

RESULTS

There were no differences in the age and sex between the BI and control group. The BI group manifested a wider pedicle and laminar than the control group at all cervical levels, except for the pedicle of C6 and C7, and the laminar of C3 and C6. In addition, the BI group had a wider lateral mass from C3 to C5 than the control group. There were no differences in most measurements of the length of pedicle, laminar, and lateral mass.

CONCLUSION

BI patients have a wider pedicle and laminar than the general population in the subaxial cervical spine, but the same size in length of pedicle, laminar, and lateral mass.Level of Evidence: 4.

Sublaminar polyester bands as a salvage fixation method in the cervical spine: novel application in two patients

Pedicle and lateral mass screws are the most common means of rigid fixation in posterior cervical spine fusions. Various other techniques such as translaminar screw placement, paravertebral foramen screw fixation, sublaminar and spinous process wiring, cement augmentation, and others have been developed for primary fixation or as salvage methods. Use of these techniques can be limited by a prior history of osteotomies, poor bone density, destruction of the bone-screw interface, and unfavorable vascular and osseous anatomy.Here, the authors report on the novel application of cervical sublaminar polyester bands as an adjunct salvage method or additional fixation point used with traditional methods in the revision of prior constructs. While sublaminar polyester bands have been used for decades in pediatric scoliosis surgery in the thoracolumbar spine, they have yet to be utilized as a method of fixation in the cervical spine. In both cases described here, sublaminar banding proved crucial for fixation points where traditional fixation techniques would have been less than ideal. Further study is required to determine the full application of sublaminar polyester bands in the cervical spine as well as its outcomes.

C3 segmental vertebral artery diagnosed by computed tomography angiography

Extremely rarely, the vertebral artery (VA) enters the subarachnoid space via the intervertebral space of the C2-3 vertebrae. We have identified three cases with this anomalous VA in the literature. We report here another case involving aberrant VA penetration of the dura at the C2-3 vertebral level diagnosed by computed tomography (CT) angiography. A 71-year-old-woman with memory disturbance underwent brain CT and CT angiography. The right VA was aberrant and penetrated the dura at the C1-2 vertebral level. On the left side, the VA penetrated the dura at the C2-3 vertebral level. To our knowledge, this anomalous VA is the first case of C3 segmental VA diagnosed by CT angiography. To prevent VA injury, it is important to identify this variation before performing a posterior fusion of the cervical vertebrae.