2023, Vol. 27 ›› Issue (27): 4337-4344

Comparison of the opening angle and cervical vertebra function of two different hinge rongeurs in French-door laminoplasty

Sun Jun1, Zhan Mingbin2, Liu Xizhe2, Liu Shaoyu1, 2, 3   

Abstract: BACKGROUND: French-door laminoplasty is a commonly used procedure for the treatment of cervical multi-segment degenerative myelopathy. At present, the prediction and control of the intraoperative opening angle need further improvement.   
OBJECTIVE: To compare the opening angle and clinical outcomes of two different hinge rongeurs in the cervical French-door laminoplasty.
METHODS: Data of 57 cervical multi-segment degenerative myelopathy patients in Seventh Affiliated Hospital of Sun Yat-sen University and First Affiliated Hospital of Sun Yat-sen University from June 2018 to June 2020 were retrospectively analyzed. The patients were divided into 20° rongeur group (n=31) and 15° rongeur group (n=26). Comparative study was made to find out the differences in functional outcomes (modified Japanese Orthopaedic Association score and visual analogue scale score), radiological outcomes (lamina angle, sagittal diameter of spinal canal, and hinge healing), and postoperative complications (axial symptoms and C5 nerve root paralysis).   
RESULTS AND CONCLUSION: (1) There was no significant difference in postoperative modified Japanese Orthopaedic Association score and postoperative visual analogue scale score between the two groups. (2) The postoperative lamina angles of the two groups were significantly higher than the preoperative lamina angles (P < 0.01). Among them, the postoperative lamina angle of the 15° hinge group (62.74±7.62)° was significantly smaller than that of the 20° hinge group (68.55±8.71)° (P < 0.01). The sagittal diameter of spinal canal of 15° rongeur group (13.52±2.16) mm was significantly lower than that of the 20° rongeur group (15.39±2.85) mm (P < 0.01). (3) At 4 weeks after operation, the fusion rate of the hinge in the 15° rongeur group was significantly higher than that of the 20° rongeur group (49%, 35%, P < 0.01). (4) There was no significant difference in the incidence of postoperative complications between the two groups. (5) It is indicated that when the hinge rongeur is used, the opening angle can be predicted before the operation and accurately controlled during the operation. Compared with the 20° hinge rongeur, using the 15° hinge rongeur to make the hinge can expand the lamina angle about 25° and reach about 63° after operation, avoiding the opening angle and the sagittal diameter of the spinal canal being too large. Both the 15° hinge rongeur and the 20° hinge rongeur can achieve satisfactory decompression effect, but the hinge healing time in the 15° hinge rongeur group is shorter, which is beneficial to the recovery of postoperative neurological function.

Key words: cervical laminoplasty, French-door, hinge rongeur, opening angle, lamina angle, hinge healing