[Clinical application of unilateral axis translaminar screws in upper cervical instability with vertebral artery variations].

OBJECTIVE

To investigate the clinical outcomes of the posterior C1,2 screw-rod combined with C2 unilateral translaminar screw and contralateral pedicle screw fixation and autogenous bicortical iliac crest graft fusion in treating upper cervical instability with vertebral artery variations.

METHODS

From June 2008 to December 2012, the clinical data of 12 patients with upper cervical instability underwent C1 lateral mass screws-C2 unilateral laminar and contralateral pedicle screws fixation combined with autogenous bicortical iliac crest graft fusion were analyzed retrospectively. There were 8 males and 4 females with a mean age of 47.5 years (ranged, 16 to 77 years). Patients suffered from occipitocervical activity limitation of motion with pain or not, VAS was 0-7 points with an average of (3.50 +/- 2.71) points. Unilateral vertebral artery hypoplasia was demonstrated by vertebral arteriography (VAG) or CTA in all patients. Cervical X-ray and CT scans were done within 7 days after surgery in order to confirm internal fixation position. Internal fixation loosening and breakage, reduction losing, bone fusion ratio were observed during follow-up.

RESULTS

No nerves and vertebral artery injuries occurred during operation. Cervical pain obviously decreased and VAS was (0.92 +/- 0.90) points. Cervical alignment of 12 patients had well-recovered by X-ray while Atlantoaxial ventral lamina cortex of 1 case was encroached by CT scan without neurological symptom. All patients were followed up for 6 months to 3 years, no internal fixation loosening and breakage, reduction losing were found. All patients obtained bone fusion in 6-12 months after operation.

CONCLUSION

Posterior C1 lateral mass screws-C2 unilateral laminar and contralateral pedicle screws fixation combined with autogenous bicortical iliac crest graft fusion can achieve biomechanical stability and raise the successful rate of bone fusion, while avoiding the risk of vertebral artery injury and overcoming the insufficient of bone fusion during bilateral laminar screws placement as well. Posterior C1 lateral mass screws fixation is a safe and effective additional method in treating upper cervical instability with vertebral artery variations.