Dynamic Changes of the Ligamentum Flavum in the Cervical Spine Assessed with Kinetic Magnetic Resonance Imaging

摘要

The purpose of this article is to quantify changes in thickness of the ligamentum flavum (LF) associated with motion of the cervical spine and to compare the thickness of the LF at each cervical level using kinetic magnetic resonance imaging (kMRI). Two hundred fifty-seven symptomatic patients (129 men; 128 women) underwent kMRI in neutral, flexion, and extension positions. Midsagittal images were digitally marked and electronically analyzed by spine surgeons. Thickness of LF in the cervical region from C2–3 to C7–T1 was measured in all three positions. LF at C7–T1 was significantly thicker than C2–3 to C6–7 in neutral, flexion, and extension positions ( p 1 A thickened LF can cause narrowing of the spinal canal and compression of neural elements that may lead to clinical symptoms of radiculopathy or myelopathy. 2 Thickening of the LF was first reported as a possible cause of spinal stenosis and associated complications by Elsberg in 1913. 3 The precise mechanism by which the LF thickens is still a topic of controversy. Many studies have attempted to explain this mechanism in ways related to hypertrophy, calcification, ossification, inflammation, or buckling due to traumatic stresses. 4 5 6 7 8 9 Compared with the thoracic and lumbar regions, LF ligaments in the cervical spine are broader and longer but also thinner. However, in relative terms, the LF in the cervical spine does occupy a significant proportion of the spinal canal, and LF thickening can cause significant narrowing and subsequent clinical symptoms. 10 11 The majority of studies investigating the thickness of the LF have examined the lumbar region. There is a paucity of studies in the literature pertaining to changes in the thickness of the LF in the cervical region. Additionally, the authors have discovered no report that uses dynamic or kinetic magnetic resonance imaging (kMRI) technology or data to investigate dynamic changes in the thickness of LF based on the position of the cervical spine. As opposed to conventional recumbent magnetic resonance imaging techniques, kMRI, which has been utilized to assess dynamic parameters of spondylosis, allows for much more physiologically accurate and functional image procurement. 12 13 The purpose of the present study is to observe, via the use of kMRI, if there are changes in the thickness of the LF associated with motion of the cervical spine (i.e., flexion and extension) and to compare the thickness of the LF at each cervical segment.