[Comparable study of alternative-level and all-level Arch mini-plate fixation for unilateral open-door laminoplasty]

Objectives: To compare the clinical effect of alternative-level and all-level Arch mini-plate fixation in patients undergoing unilateral open-door laminoplasty. Methods: Clinical data of 134 patients administrated in the Peking University International Hospital for multistage cervical spondylotic myelopathy from March 2015 to March 2019 were reviewed retrospectively. There were 63 males and 71 females with an average age of (62±8) years and a mean disease course of (18±7) months (3-37 months). All the patients underwent posterior cervical unilateral open-door laminoplasty with Arch titanium plate fixation. All the patients were divided into two groups according to the different amount of titanium plates used during operation as follow: group A, Arch plates were fixed at the door sides of C₃, C₅ and C₇ (n=68) and group B, Arch plates were fixed at the door sides of C₃, C₄, C₅, C₆ and C₇ (n=66). Operation time, intraoperative blood loss, postoperative hospitalization days and the cost of consumables, the Japanese orthopaedic association (JOA) score, cervical dysfunction index (NDI), the rates of improved JOA score, cervical curvature index, C_2-7 Cobb angle, cervical range of motion, sagittal diameter of vertebral canal, opening angle of laminar, hinges bone healing and surgery related complications (axial symptoms, C₅ nerve root palsy, screw loosening, laminar re-closing, cervical kyphosis, etc.) were recorded and compared between the two groups. Results: There was no complications during the operation, and the mean follow-up was (20±8) months (14-48 months). There was no statistically significant difference between the two groups in terms of gender, age, course of disease and compression segments (all P>0.05). There was no statistically significant differences between the two groups in operation time, intraoperative blood loss and postoperative hospital stay too (all P>0.05). The cost of consumables in group A was (34 970±1 325) yuan, and it was (57 450±2 161) yuan in group B, the difference between the two groups was statistically significant (P<0.01). The JOA and NDI score were significantly improved 3 months and 1 year after operation in both groups (both P<0.05). The sagittal diameter of each segment of the spinal canal at C₃, C₄, C₅, C₆ and C₇ were all significantly increased in both groups 3 months and 1 year after surgery (all P<0.05). The C_2-7 Cobb angle and cervical curvature index were all significantly reduced in both groups 3 months and 1 year after surgery (all P<0.05). The cervical range of motion in both groups was significantly reduced 3 months and 1 year after surgery compared with that before surgery (both P<0.05). The range of motion of the cervical spine in group A was significantly higher than that in group B (P<0.05). The opening angles of C₄ and C₆ segment lamina in group A 3 months and 1 year after operation were significantly lower than those in group B (all P<0.05). At 3 months after the operation, the hinges healing rate of C₄ and C₆ in group B was significantly better than that of group A (both P<0.05). At 1 year after the operation, there was no difference in the hinges healing rate of C₄ and C₆ in the two groups (both P>0.05). There was no statistically significant difference in postoperative complications between the two groups (P>0.05). Conclusions: The safety and early clinical efficacy of alternative-level and all-level Arch titanium plate fixation in posterior cervical unilateral open-door laminoplasty are comparable, alternative-level fixation can effectively reduce the cost of hospitalization. The open Angle loss and lower early hinges healing rate of the non-fixed segment in the alternative-level fixed group does not lead to laminar re-closing in early period of post operation.