1. Evaluating Changes to the Modified K-Line Using Kinematic MRIs.
- Author
-
Bajouri Z, Telang S, Fresquez Z, Kim M, Gilbert Z, Pickering T, Buser Z, Hah RJ, Wang JC, and Alluri RK
- Subjects
- Humans, Retrospective Studies, Biomechanical Phenomena, Cross-Sectional Studies, Magnetic Resonance Imaging methods, Cervical Vertebrae diagnostic imaging, Cervical Vertebrae surgery, Cervical Vertebrae pathology
- Abstract
Study Design: Retrospective cross-sectional review of a large database., Objective: Little is known regarding extension K-lines for treatment of cervical myelopathy. Therefore, this study seeks to examine differences between K-lines drawn in neutral and extension., Summary of Background Data: The modified K-line is a radiological tool used in surgical planning of the cervical spine. As posterior cervical decompression and fusion often results in patients being fused in a more lordotic position than the preoperative neutral radiograph, a K-line measured in the extension position may offer better utility for these patients., Materials and Methods: Total of 97 patients were selected with T2-weighted, upright cervical magnetic resonance imaging taken in neutral and extension. For each patient, the K-line was drawn at the mid-sagittal position for both neutral and extension. The distance from the most posterior portion of each disk (between C2 and C7) to the K-line was measured in neutral and extension and the difference was calculated. Paired t test was used to assess significant differences., Results: Across all levels between C2 and C7 there was an increase in the distance between the dorsal aspect of the disk and K-line when comparing neutral and extension radiographs. The average change in difference (extension minus neutral) at each cervical spinal level was 0.9 mm (C2-C3), 2.5 mm (C3-C4), 2.6 mm (C4-C5), 2.0 mm (C5-C6), and 0.9 mm (C6-C7). A paired t test showed that the K-line increase from neutral to extension was statistically significant across all disk levels ( P <0.001)., Conclusion: When positioned in extension, patients experience a significant increase in distance from the dorsal aspect of a disk to the K-line compared to when positioned in neutral, especially between C3 and C6. This is clinically relevant for surgeons considering a posterior cervical decompression and fusion in patients with a negative modified K-line on preoperative magnetic resonance imaging, as these patients may have enough cervical cord drift back when fused in an extended position, maximizing likelihood of improving postoperative DSM functional outcomes., Competing Interests: Z.B.—consultancy: Cerapedics (past), Research Support: SeaSpine (past, paid to the institution), Next Science (paid directly to institution), Medical Metrics (past, paid directly to institution), NIH SBIR Subaward (paid to institution); North American Spine Society: committee member; Lumbar Spine Society: Co-chair Educational Committee, AOSpine Knowledge Forum Degenerative: Associate member; AOSNA Research committee—committee member: patents (issued): Biomarkers for painful intervertebral discs and methods of use thereof. R.J.H.: consultant and royalties NuVasive, research support (paid to institution): si-bone and a-tec, committees: NASS, LSRS, editorial board: GSC. J.C.W.: Royalties—Biomet, Seaspine, Synthes, Investments/Options—Bone Biologics, Pearldiver, Electrocore, consulting: precision OS, Board of Directors—AO Foundation, National Spine Health Foundation, Editorial Boards—Global Spine Journal Editor-in-Chief, Fellowship Funding (paid to institution): AO Foundation. R.K.A.: stock options from HIA, Senior Reviewer for IJSS. The remaining authors report no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)
- Published
- 2023
- Full Text
- View/download PDF