European Spine Journal
K‑line tilt as a novel radiographic parameter in cervical sagittal
Hyun Sik Kim
· Tae Hwan Kim
· Moon Soo Park
· Seok Woo Kim
· Ho Geun Chang
· Ji Hee Kim
· Jun Hyong Ahn
In Bok Chang
· Joon Ho Song
· Jae Keun Oh
Received: 4 January 2018 / Revised: 5 April 2018 / Accepted: 11 May 2018
© Springer-Verlag GmbH Germany, part of Springer Nature 2018
Objective To investigate the relationship between the K-line tilt and classical cervical parameters such as the C2–C7 sagittal
vertical axis (SVA), cervical lordosis, and the T1 slope in cervical sagittal alignment. We assessed whether the K-line tilt
can be used as an excellent cervical parameter.
Methods We reviewed 50 patients aged 60–89 years who visited the spine center outpatient clinic from May 2017 to Sep-
tember 2017 through cervical spine lateral radiography and checked the cervical spine parameters. All targeted patients were
randomized without any prejudice. Radiographic measurements included the K-line tilt, C2–C7 lordosis, the C2–C7 SVA,
the T1 slope, and T1 slope minus C2–C7 lordosis (T1S-CL). Pearson correlation coeﬃcients were calculated between the
K-line tilt and each cervical parameter.
Results Of the 50 patients, 33 were men. The mean age of the patients was 70.84 ± 7.52 years. The mean K-line tilt was
11.28 ± 8.31°. The K-line tilt was correlated with the C2–C7 SVA (r = 0.813, P = 0.000) and T1S-CL (r = 0.315, P = 0.026).
Conclusion This study showed that the K-line tilt is also a useful parameter like the C2–C7 SVA and T1S-CL in cervical
Graphical Abstract These slides can be retrieved under Electronic Supplementary Material.
1. Cervical Sagittal Alignment
2. T1 slope
3. C2-7 Sagittal Vertical Axis
4. K-line Tilt
Take Home Messages
1. There is a direct proportion between the K-line tilt and C2-C7 SVA.
2. We can use the K-line tilt as a radiographic parameter for assessing
Keywords Cervical sagittal alignment · T1 slope · Cervical lordosis
Many studies have investigated the important radiographic
parameters inﬂuencing the thoracolumbar spine. How-
ever, relatively few studies have evaluated these impor-
tant radiographic parameters for cervical alignment [4,
12]. The cervical spine not only stands the mass of head
but also permits the wider range of motion relative to the
Electronic supplementary material The online version of this
article (https ://doi.org/10.1007/s0058 6-018-5634-9) contains
supplementary material, which is available to authorized users.
* Jae Keun Oh
Extended author information available on the last page of the article