Influence of fixed titanium plate position on the effectiveness of open-door laminoplasty for cervical spondylotic myelopathy.

Background: During open-door laminoplasty, the position of the bone gutter is not fixed, and when the gutter migrates inward, the outer end of the titanium plate must be fixed on the lamina edge. It is unclear whether this will affect the clinical efficacy. This study aimed to observe the influence of the titanium plate fixation position on the effectiveness of open-door laminoplasty for cervical spondylotic myelopathy (CSM).

Methods: A total of 98 patients with CSM who underwent open-door laminoplasty from August 2016 to October 2019 were included in this retrospective study. Fifty-five patients had the titanium plate fixed on the lateral mass (lateral mass group), and 43 patients had the titanium plate fixed on the lamina edge (lamina group). The opening angle, opening width, occurrence of hinge fracture, spinal cord drift distance, cervical curvature index (CCI), neurological function recovery (JOA score), neck function (NDI), C5 palsy and severity of axial symptoms were observed and compared between the two groups.

Results: The opening angle in the lamina group was significantly larger than that in the lateral mass group, while the opening width and the spinal cord drift distance were significantly smaller than those in the lateral mass group (P < 0.05). The occurrence of hinge fracture in the lamina group was significantly higher than that in the lateral group (25.6% and 9.1%, respectively) (P < 0.05). The CCI was maintained well in both groups (P > 0.05), and there was no significant difference between the groups (P > 0.05). After surgery, the JOA score significantly increased in both groups (P < 0.05), and the neurological recovery rates were similar between the two groups (62.6% vs. 64.5%). The NDI score significantly decreased in both groups (P < 0.05), but the lateral mass group recovered to a greater degree than the lamina group (P < 0.05). The occurrence of C5 palsy was 2.3% in the lamina group and 14.5% in the lateral mass group, and there was a significant difference between the groups (P < 0.05). Postoperative axial symptom severity was significantly worse in the lamina group than in the lateral mass group (P < 0.05).

Conclusions: In open-door laminoplasty, it is feasible to fix the titanium plate on the lateral mass or to the lamina due to the same neurological function recovery. However, fixing it to the lamina will increase the opening angle and decrease the opening width, making the hinge prone to fracture and increasing the severity of postoperative axial symptoms.