Comparison of clinical outcomes of modified laminoplasty with preservation of muscle group inserted into C2 and C7 spinous processes versus conventional C3–C7 laminoplasty: a prospective, randomized, controlled, noninferiority trial
Authors: Lin Wancheng , Song Jipeng , Zhang Yao , Yao Siyuan , Yi Meng , Yao Mingtao , Fan Yuyu , Luo Zhengning , Ding Lixiang 
Published: March 2023

Background:
The efficacy and noninferior of performing modified double-door laminoplasty (MDDL) (C4–C6 laminoplasty plus C3 laminectomy, alongside a dome-like resection of the inferior part of the C2 lamina and the superior part of the C7 lamina) in patients with multilevel cervical spondylotic myelopathy (MCSM) is equivocal. A randomized, controlled trial is warranted.

Objective:
The objective was to evaluate the clinical efficacy and noninferior of MDDL compared with traditional C3–C7 double-door laminoplasty.

Study design:
A single-blind, randomized, controlled trial.

Methods:
A single-blind, randomized, controlled trial was conducted in which patients who with MCSM with greater than or equal to 3 levels of spinal cord compression from the C3 to the C7 vertebral levels were enrolled and assigned to undergo either MDDL group or conventional double-door laminoplasty (CDDL) group in a 1:1 ratio. The primary outcome was the change in the Japanese Orthopedic Association score from baseline to 2-year follow-up. The secondary outcomes included changes in the Neck Disability Index (NDI) score, the Visual Analog Scale (VAS) for neck pain, and imaging parameters. Operative complications were also collected and reported. The outcome measures were compared between the groups at 3 months, 1 year, or 2 years after surgery.

Results:
A total of 96 patients (mean age 67 years, 39.8% women) underwent randomization. Of these patients, 93 completed 3-month follow-up, 79 completed 1-year follow-up, and 66 completed 2-year follow-up. The changes in the Japanese Orthopedic Association score did not differ significantly between the study groups at the three time points after surgery. With respect to amelioration of neck pain and disability related to neck pain, patients in the MDDL group had a significantly greater decrease in the VAS and NDI component summary score than did those in the CDDL group at 1-year (VAS: −2.5 vs. −3.2, difference −0.7, 95% CI −1.1 to −0.2, P=0.0035; NDI: −13.6 vs. −19.3, difference −5.7, 95% CI −10.3 to −1.1, P=0.0159) and 2-years (VAS: −2.1 vs. −2.9, difference −0.8, 95% CI −1.4 to −0.2, P=0.0109; NDI: −9.3 vs. −16.0, difference −6.7, 95% CI −11.9 to −1.5, P=0.0127). The changes in the range of motion (ROM), the C2–C7 Cobb angle, and the cervical sagittal vertical axis in the MDDL group were significantly less than those in the CDDL group (ROM: −9.2±6.4 vs. −5.0±6.0, P=0.0079; C2–C7 Cobb angle: −7.9±7.8 vs. −4.1±6.2, P=0.0345; cervical sagittal vertical axis: 0.6±0.9 vs. 0.2±0.6, P=0.0233). The MDDL group had less blood loss (428.1 vs. 349.1, P=0.0175) and a lower rate of axial symptoms (27.3 vs. 6.1%, P=0.0475) than the CDDL group.

Conclusions:
Among patients with MCSM, the MDDL produced similar cervical cord decompression compared with the conventional C3–C7 double-door laminoplasty. The modified laminoplasty was associated with meaningful improvement in amelioration of neck discomfort, maintaining a better cervical ROM and sagittal alignment, decreasing blood loss, and reducing the incidence of axial symptoms.