Impact of C3 laminectomy on cervical sagittal alignment in cervical laminoplasty: a prospective, randomized controlled trial comparing clinical and radiological outcomes between C3 laminectomy with C4–C6 laminoplasty and C3–C6 laminoplasty

• Published in: The spine journal 2023-11, Vol.23 (11), p.1674-1683
• Main Authors: Kim, Jun-Hoe, Yuh, Woon Tak, Han, Junghoon, Kim, Taeshin, Lee, Chang-Hyun, Kim, Chi Heon, Choi, Yunhee, Chung, Chun Kee
• Format: Article
• Language: English
• Subjects: C3 laminectomy; Cervical lordosis; CSM; Laminoplasty; OPLL; Sagittal vertical axis
• ISSN: 1529-9430; 1878-1632
• DOI: 10.1016/j.spinee.2023.07.001

C3 laminectomy in cervical laminoplasty is a modified laminoplasty technique that can preserve the semispinalis cervicis muscle attached to the C2 spinous process. Several previous studies have shown that this technique can lead to better outcomes of postoperative axial neck pain and C2–C3 range of motion (ROM) than conventional cervical laminoplasty. However, there is still a lack of understanding of total and proportional postoperative cervical sagittal alignment outcomes. To assess the effects of C3 laminectomy in cervical laminoplasty on postoperative cervical alignment and clinical outcomes. A single-center, patient-blinded, randomized controlled trial. We included consecutive 126 patients diagnosed with cervical spondylotic myelopathy (CSM) or ossification of posterior longitudinal ligament (OPLL) who were scheduled for cervical laminoplasty from March 2017 to January 2020. The primary outcome measures were C2–C7 Cobb angle (CA) and neck disability index (NDI). Secondary outcomes measures included other clinical outcomes and radiographic parameters including segmental Cobb angle and presence of C2–C3 interlaminar fusion. Patients were randomly allocated to either the C3 laminectomy with C4–C6 laminoplasty group (LN group) or the C3–C6 laminoplasty group (LP group) at a 1:1 ratio. Laminoplasty was performed using a unilateral open-door technique and stabilized with titanium mini plates. A linear mixed model analysis was employed to examine the longitudinal data from postoperative 1-year through 3-year. Additional analysis between three types of cervical sagittal alignment morphology was done. Among 122 patients who were randomly allocated to one of two groups (LN group, n=61; LP group, n=61), modified intent-to-treat analysis was done for 109 patients (LN group, n=51, LP group, n=58) who had available at least a year of postoperative data. Postoperative C2–C7 CA was not significantly different between the two groups. However, NDI was significantly different between the two groups (12.8±1.0 in the LN group vs 8.6±1.0 in LP group, p=.005), which exceeded the minimum clinically important difference (MCID). The postoperative C2–C3 CA was significantly greater in the LN group (7.1±0.5° in LN group vs 3.2±0.5° in LP group, p