K-Line

The K-line is a straight line connecting the midpoints of the cervical spinal canal at C2 and C7 on a neutral cervical lateral radiograph.

The maximum occupying ratio of the cervical ossification of the posterior longitudinal ligament (OPLL) is calculated from a cervical sagittal computed tomography.

see K-line negative.

Various radiological parameters are used to evaluate cervical ossification of the posterior longitudinal ligament and to determine the surgical strategy. Factors such as the number of involved spinal segments, cervical alignment or T1 slope, the relationship between OPLL and the C2–7 line (termed the “K-line”), occupying ratio of OPLL, and involvement of dural ossification need to be carefully considered before surgery ¹⁾.