Ipsilateral Fixation and Reconstruction of the Cervical Spine after Resection of a Dumbbell Tumor Via a Unilateral Posterior Approach: A Case Report and Biomechanical Study.

Objective: There is lack of an internal fixation following resection of a dumbbell tumor by hemi‐laminectomy and facetectomy that achieves adequate stability with less trauma. Unilateral fixation and reconstruction (unilateral pedicle screw and contralateral lamina screw fixation combined with lateral mass reconstruction, UPS + CLS + LM) may be an ideal technique to address this problem. A biomechanical comparison and a case report were designed to evaluate its spinal stability and clinical effect. Methods: Seven fresh‐frozen human subcervical specimens were used for the biomechanical testing. The conditions tested were: (1) intact; (2) injured (single‐level hemi‐laminectomy and facetectomy); (3) unilateral pedicle screw (UPS) fixation; (4) UPS fixation combined with lateral mass (LM) reconstruction (UPS + LM); (5) UPS fixation and contralateral lamina screw fixation (UPS + CLS); (6) UPS + CLS + LM; (7) UPS fixation and contralateral transarticular screw fixation (UPS + CTAS); (8) bilateral pedicle screw (BPS) fixation. Range of motion (ROM) and neutral zone (NZ) were obtained at C5‐C7 segment under eight conditions. In addition, we report the case of a patient with a C7‐T1 dumbbell tumor that was treated by UPS + CLS + LM technique. Results: Except left/right lateral bending and right axial rotation (all, p < 0.05), ROM of UPS + CLS + LM condition in other directions was similar to that of BPS condition (all, p > 0.05). There was no significant difference between UPS + CLS + LM and the UPS + CTAS condition in other directions of ROM (all, p > 0.05), except in left/right axial rotation (both, p < 0.05). Compared to UPS + CLS condition, left/right lateral bending ROM of UPS + CLS + LM condition were significantly reduced (both, p < 0.05). UPS + CLS + LM condition significantly reduced ROM in all directions compared to UPS and UPS + LM condition (all, p < 0.05). Similarly, except lateral bending (p < 0.05), there was no difference in NZ in other directions between UPS + CLS + LM and BPS condition (both, p > 0.05). There was no significant difference between UPS + CLS + LM and UPS + CTAS condition in NZ in all directions (all, p > 0.05). Axial rotation NZ of UPS + CLS + LM condition was significantly reduced compared to UPS + CLS condition (p < 0.05). Compared to UPS and UPS + LM condition, NZ of UPS + CLS + LM condition was significantly reduced in all directions (all, p < 0.05). The patient's imaging examination at 3 months postoperatively indicated that the internal fixation did not move and the graft bone was seen with fusion. Conclusion: After resection of a dumbbell tumor in the cervical spine, UPS + CLS + LM technique is a reliable internal fixation method to provide sufficient immediate stability and promote postoperative bone fusion. [ABSTRACT FROM AUTHOR]