Posterior unilateral exposure and stability reconstruction with pedicle and lamina screw fixation for the cervical dumbbell tumorectomy: a case report and biomechanical study.

Abstract

Cervical dumbbell tumor is usually removed via a posterior approach and may require the spinal fixation sometimes. However, the present surgical methods involved either more trauma or a higher risk of instability of the cervical spine. A new technique of unilateral exposure and stability reconstruction with pedicle and lamina screws fixation for posterior cervical dumbbell tumorectomy was described and compared with conventional techniques. Posterior unilateral exposure, hemi-laminectomy and facetectomy were performed in one patient with the cervical dumbbell tumor between C3 and C4. The stability was reconstructed by the unilateral pedicle and lamina screws fixation (UPLS), and a strip of shaped allograftbone was also implanted between the superior and inferior lateral mass. Biomechanical stability test of this new technique was investigated using seven fresh-frozen human cervical spine specimens (C4-C7) and compared with unilateral pedicle screw (UPS) and bilateral pedicle screw fixation (BPS) techniques. A continuous pure moment of ± 2.0 Nm was applied to the specimen in flexion, extension, lateral bending and axial rotation. The cervical dumbbell tumor was removed completely, and bone fusion with continuous bone trabecula was maintained in the patient on the final follow-up examination at 18months postoperatively. Biomechanical stability tests revealed that the range of motion of the UPLS fixation plus graft bone implant was the same as the BPS fixation in flexion (1.8°vs. 1.5°, p = 0.58) and extension (2.3°vs. 2.2°, p = 0.73), but significantly bigger in lateral bending (3.9° vs. 1.0°, p < 0.001) and axial rotation (6.8° vs. 3.8°, p = 0.002), which were significantly smaller than the UPS fixation in all directions (all p < 0.001). For the treatment of cervical dumbbell tumor, posterior unilateral exposure and stability reconstruction with pedicle and lamina screws fixation following hemi-laminectomy and facetectomy appear to be a more stable and lesser trauma technique. Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.