13. Preoperative range of motion from neutral to extension position can be a predictive factor for loss of cervical lordosis after cervical laminoplasty.

BACKGROUND CONTEXT Cervical laminoplasty is one of the effective surgical procedures for degenerative cervical myelopathy (DCM). However, kyphotic deformity due to loss of cervical lordosis (CL) is a relatively common complication after cervical laminoplasty, which can be a risk factor for poor surgical outcomes. PURPOSE Current study aimed to identify the predictive factors for loss of CL after cervical laminoplasty and to demonstrate the effect of the loss of CL on clinical outcomes. STUDY DESIGN/SETTING Multicenter, retrospective cohort study. PATIENT SAMPLE Patients with DCM who underwent open-door laminoplasty between February 2019 and December 2021 were included. OUTCOME MEASURES Demographic, operative, radiographic and clinical score data were collected preoperatively and 1 year postoperatively. Radiographic factors included cervical sagittal vertical axis (cSVA), C2-7 lordotic angle (neutral, extension, and flexion position), C2-7 range of motion (ROM), C2-7 extension ROM (neutral to extension: eROM), and C2-7 flexion ROM (neutral to flexion). Clinical scores included JOA scores, VAS (neck pain, upper extremity paresthesia, and pain), EQ-5D-5l, JOACMEQ, and NDI. Clinical scores were also collected at 2-years postoperatively. METHODS Loss of CL was defined as decreasing of C2-7 lordotic angle >10° from preoperative to 1-year postoperative ones. Patients were divided into two groups based on loss of CL: the Loss group and the No-loss group. As univariate analysis, all collected data were compared between groups. Receiver Operating Characteristic (ROC) curve analysis was performed for the significant variables in the univariate comparisons. Finally, multivariate logistic regression analysis was performed to identify the factors relating to loss of CL development. As subanalysis, clinical scores at 2-years postoperatively were also compared between groups using the data of patients who could followed >2 years postoperatively by December 2022. RESULTS Among 178 patients (mean age 73.2 years), 40 patients (22.5%) demonstrated loss of CL at 1-year postoperatively. In univariate comparisons, preoperative eROM was significantly smaller in the Loss group than in the No-loss group (6.9 vs 13.3, p<0.001). However, no other factors showed significant differences between groups. ROC analysis demonstrated that preoperative eROM could predict the development of loss of CL significantly (area under curve=0.74, 95% confidence interval [CI]: 0.65 to 0.82, p<0.001) with a threshold as 9.0° (sensitivity 0.66, specificity 0.65). Multivariate logistic regression analysis revealed that preoperative eROM <9.0 was significantly related with loss of CL development at 1-year postoperatively independent from patient age, sex, preoperative JOA score, cSVA, C2-7 lordotic angle at neutral position (adjusted odds ratio=3.78, 95% CI: 1.65 to 8.67, p=0.020). In subanalysis, VAS of neck pain was significantly worse in Loss group than in No-loss group at 2-years postoperatively (26.7 vs 9.9, p<0.01, n=18 and 52 in Loss and No-loss group, respectively). CONCLUSIONS Current study identified that preoperative small eROM (<9.0°) can be a useful predictive factor for loss of CL after cervical laminoplasty. Additionally, the loss of CL might impact on the neck pain after 2-years postoperatively. These data can be helpful to establish adequate surgical strategy for patients with DCM. FDA Device/Drug Status This abstract does not discuss or include any applicable devices or drugs.