Ono Kosei, Murata Sohei, Matsushita Mutsumi, Murakami Hiroshi
Department of Orthopedic Surgery, Kurashiki Central Hospital, Okayama, Japan.
Neurospine. 2021 Jun;18(2):311-318. doi: 10.14245/ns.2040700.350. Epub 2021 Jan 22.
Maintaining cervical lordosis (CL) after laminoplasty is important for indirect decompression of the spinal cord. This study aimed to identify preoperative dynamic radiographic predictors for the loss of CL after laminoplasty.
We retrospectively analyzed 141 consecutive patients who underwent cervical laminoplasty for cervical myelopathy. The following radiographic parameters were measured before surgery and at 1 year of follow-up: CL, C7 slope, C2-7 sagittal vertical axis (SVA), C2-7 range of motion (ROM), CL in flexion, CL in extension, ROM of flexion (Flex ROM), and ROM of extension. The CL ratio (CLR) was defined as 100 × Flex ROM/ C2-7 ROM. ΔCL was defined as postoperative CL minus preoperative CL. Patients were classified into 2 groups: group K (kyphotic change group, ΔCL ≤ -10) and group C (control group, ΔCL > -10).
The patient population comprised 94 men and 47 women (mean age, 70.9 ± 9.4 years), with 24 patients (17.0%) classified into group K. CL, C7 slope, and CLR were significantly higher in group K than in group C. The groups did not significantly differ in age, sex, C2-7 SVA, and C2-7 ROM. On multivariable analysis, the CLR was significantly associated with postoperative kyphotic changes. On receiver-operating characteristic curve analysis (area under the curve = 0.717, p < 0.001), the cutoff value for CLR was 68.9%, with sensitivity and specificity of 87.5% and 57.3%, respectively.
The CLR, reflecting the balance between flexion and extension mobility, was identified as a novel predictor for CL loss after laminoplasty, with a cutoff value of 68.9%.
椎板成形术后维持颈椎前凸（CL）对脊髓间接减压很重要。本研究旨在确定椎板成形术后CL丢失的术前动态影像学预测因素。
我们回顾性分析了141例因颈椎病接受颈椎椎板成形术的连续患者。在手术前和随访1年时测量以下影像学参数：CL、C7斜率、C2-7矢状垂直轴（SVA）、C2-7活动范围（ROM）、屈曲位CL、伸展位CL、屈曲活动范围（Flex ROM）和伸展活动范围。CL比率（CLR）定义为100×Flex ROM/C2-7 ROM。ΔCL定义为术后CL减去术前CL。患者分为两组：K组（后凸改变组，ΔCL≤-10）和C组（对照组，ΔCL＞-10）。
患者群体包括94名男性和47名女性（平均年龄，70.9±9.4岁），24例患者（17.0%）被归入K组。K组的CL、C7斜率和CLR显著高于C组。两组在年龄、性别、C2-7 SVA和C2-7 ROM方面无显著差异。多变量分析显示，CLR与术后后凸改变显著相关。在受试者工作特征曲线分析中（曲线下面积=0.717，p＜0.001），CLR的截断值为68.9%，敏感性和特异性分别为87.5%和57.3%。
反映屈伸活动度平衡的CLR被确定为椎板成形术后CL丢失的新预测因素，截断值为68.9%。
