Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan.
Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan.
J Orthop Sci. 2022 May;27(3):551-557. doi: 10.1016/j.jos.2021.02.005. Epub 2021 Apr 14.
The K-line in the neck-flexed position (FK-line) on radiography reflects dynamic factors and cervical alignment. Although the FK-line has been reported to affect the neurological recovery after muscle-preserving selective laminectomy for cervical spondylotic myelopathy (CSM), its influence on surgical outcomes after expansive open-door laminoplasty (ELAP) has not been investigated.
We reviewed the surgical outcomes in 81 patients with multilevel CSM who underwent C4-C6 ELAP combined with C3 and C7 partial laminectomy using a laminoplasty plate and were followed up for at least 2 years. We defined the K-line (-) as some portion of a bony spur or the vertebral body crossing the FK-line, whereas the FK-line (+) was defined as that never crossing the FK-line. Patients were divided into the FK-line (+) (n = 61) and FK-line (-) groups (n = 20), and the surgical outcomes were compared between the groups. A multivariate analysis was performed to identify the factors that influenced the neurological outcomes.
The FK-line (-) group had a smaller C2-C7 angle, smaller C7 slope, greater postoperative increase in the C2-C7 sagittal vertical axis, greater kyphosis in cervical flexion and less lordosis in cervical extension, and higher incidence of postoperative residual spinal cord compression. The preoperative-to-postoperative changes in the Japanese Orthopedic Association (JOA) score and JOA score recovery rate (RR) were lower in the FK-line (-) group. The multiple linear regression analysis revealed that the K-line (-) (β = -0.327, P = 0.011) and high signal intensity (SI) changes on T2-weighted imaging (WI) combined with the low SI changes on T1-WI in the spinal cord (β = -0.320, P = 0.013) negatively affected the JOA score RR.
The FK-line can be used for patients with CSM as a simple indicator of neurological outcomes after ELAP.
颈椎伸展位（FK 位）的 K 线反映了颈椎的动态因素和排列情况。尽管已有研究报道 FK 线会影响颈椎管狭窄症患者保留肌肉的选择性椎板切除术（CSM）后的神经恢复，但它对扩大型开门椎板成形术（ELAP）后的手术结果的影响尚未被研究。
我们回顾了 81 例接受 C4-C6 颈椎 ELAP 联合 C3 和 C7 部分椎板切除术的多节段 CSM 患者的手术结果，这些患者使用椎板成形术板进行了至少 2 年的随访。我们将 K 线（-）定义为骨赘或椎体的一部分穿过 FK 线，而 FK 线（+）定义为从未穿过 FK 线。将患者分为 FK 线（+）组（n=61）和 FK 线（-）组（n=20），并比较两组的手术结果。进行多变量分析以确定影响神经功能结果的因素。
FK 线（-）组的 C2-C7 角更小，C7 斜率更大，术后 C2-C7 矢状垂直轴增加更大，颈椎伸展时后凸增加，颈椎屈曲时前凸减少，术后残留脊髓压迫的发生率更高。FK 线（-）组的日本矫形协会（JOA）评分术前到术后的变化和 JOA 评分恢复率（RR）较低。多元线性回归分析显示，K 线（-）（β=-0.327，P=0.011）和脊髓 T2 加权成像（WI）上的高信号强度（SI）改变与 T1-WI 上的低 SI 改变相结合（β=-0.320，P=0.013）对 JOA 评分 RR 有负面影响。
FK 线可用于 CSM 患者，作为 ELAP 后神经功能结果的简单指标。
