Modified K-Line in Neck Extension Is a Prognostic Indicator of the Surgical Outcome at 5 Years After Cervical Laminoplasty for Cervical Spondylotic Myelopathy

Takeuchi, Kazunari; Yokoyama, T.; Wada, Kanichiro; Kumagai, Gentaro; Kudo, Hitoshi; Tanaka, Sunao; Asari, Toru; Sasaki, Eiji; Koyama, Kazushige; Ichinohe, Masayuki; Ishibashi, Yasuyuki

doi:10.1097/brs.0000000000003982

Cited by 8 publications

(10 citation statements)

References 15 publications

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“…Clinically, this is an important finding for surgeons considering a posterior cervical decompression and fusion as a subset of patients may convert from K-line (−) to (+) in extension and experience an increase in the potential space for spinal cord drift back after fusion. Currently, literature cites increased disk-to-K-line space as a predictive feature for improved postoperative functional outcomes for DCM2,4,6—to which our study findings demonstrate that there may be a subset of patients who convert from K-line (−) to K-line (+) and may benefit from only a posterior decompression and fusion as compared to an anterior procedure or combined anterior-posterior cervical procedure.…”

Section: Discussionmentioning

confidence: 61%

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Evaluating Changes to the Modified K-Line Using Kinematic MRIs

Bajouri¹,

Telang

Fresquez

et al. 2022

Spine

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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.

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Section: Discussionmentioning

confidence: 61%

“…Thus, providing a new “neutral” for these patients. Currently, little is known about the K-Line and its utility on extension radiographs 6. In addition, changes to pathological features—in particular, disk herniations and their distance to the K-line—for K-lines drawn in neutral and those drawn in extension are poorly characterized.…”

mentioning

confidence: 99%

Evaluating Changes to the Modified K-Line Using Kinematic MRIs

Bajouri¹,

Telang

Fresquez

et al. 2022

Spine

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“…When laminoplasty was performed in this group, the recovery rate of the cervicalJapanese Orthopedic Association (JOA) scores was very poor. 26 Takeuchi et al 18 investigated outcomes after cervical laminoplasty for CSM using the mK-line. They found that in patients in whom the K-line crossed the ventral edge of any spinous process, this was predictive of poor neurological outcomes after laminoplasty for CSM.…”

Section: K-line and Mk-linementioning

confidence: 99%

Radiographic Parameters in Cervical Myelopathy

Waddell¹,

Vaughan²,

Abtahi

2022

Clinical Spine Surgery: A Spine Publication

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Study Design: This was a narrative review. Objectives: Provide a comprehensive review of radiographic alignment parameters and their effect on procedure selection, surgical decision-making, and clinical outcomes for the treatment of cervical spondylotic myelopathy (CSM). Summary of Background Data: The use of radiographic parameters to predict prognosis and surgical outcomes in patients with CSM is an evolving field given the complex presentation of patients with this condition. Methods: A literature search was conducted using PubMed for surgical treatment of CSM, with an emphasis on cervical radiographic parameters and clinical outcomes. Results: The principal goals of spine surgery can be broken down into decompression, stabilization, and restoration of alignment. The principle of restoring balance takes careful preoperative planning and attention to radiographic parameters including cervical lordosis, C2–C7 sagittal vertical axis, neck tilt, thoracic inlet angle, T1 slope, K-line, and modified K-line. Surgical interventions for CSM include anterior cervical discectomy and fusion, posterior cervical fusion, or laminoplasty and careful consideration of radiographic measures guide surgical decision-making is essential to ensure optimal outcomes. Conclusion: Utilization of key radiographic parameters in surgical planning and decision-making allows surgeons to optimize clinical outcomes for CSM. Level of Evidence: Level V.

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“…Although the modified K-line is a useful and convenient method to decide surgical indication of posterior decompression surgery, previous studies targeted only double-door laminoplasty, and there is limited evidence of comprehensive clinical results in terms of cervical alignment changes and patient-reported functional outcomes postoperatively. [10][11][12] Therefore, it is quite meaningful from our therapeutic experience to present the surgical outcomes of patients who had preoperative cervical spinal kyphosis and underwent unilateral open-door laminoplasty. This study aimed to investigate the cervical dynamics, neurological function, pain, and quality of life (QoL) in these patients.…”

Section: Neurospine Eissn 2586-6591 Pissn 2586-6583mentioning

confidence: 99%

Surgical and Functional Outcomes of Expansive Open-Door Laminoplasty for Patients With Mild Kyphotic Cervical Alignment

et al. 2021

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Objective: To evaluate the cervical dynamics, neurological function, pain, and quality of life in patients with mild cervical kyphotic alignment who underwent expansive unilateral open-door laminoplasty (ELAP).Methods: In this retrospective single-center study, we reviewed the surgical outcomes of 80 patients with cervical spondylotic myelopathy who were followed for at least 2 years. The patients were categorized into the preoperative kyphotic group (C2–7 angle < 0°) and nonkyphotic group (angle ≥ 0°). We compared clinical information, radiographic parameters, Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ) scores, and cervical Japanese Orthopaedic Association (JOA) scores between the groups.Results: The kyphotic and nonkyphotic groups comprised 17 and 63 patients, respectively. The preoperative C2–7 angles were -3.7° in the kyphotic group and 15.4° in the nonkyphotic group (p < 0.01). In the kyphotic group, kyphotic alignment improved to lordosis at the final follow-up (2.6°, p = 0.01). The preoperative (16.4° vs. 24.1°, p < 0.01) and finalfollow-up (17.8° vs. 24.5°, p < 0.01) C7 slopes were significantly smaller in the kyphotic group. ELAP reduced pain in the arms or hands (p = 0.02) and improved the JOA scores (p < 0.01) in the kyphotic group. Patient-reported outcomes assessed using the JOACMEQ showed comparable effective rates in both groups.Conclusion: Patients with mild cervical kyphosis showed smaller C7 slopes as a compensatory mechanism. Kyphotic angles significantly improved to lordosis after ELAP, resulting in favorable clinical outcomes. ELAP is a useful surgical option for patients even if they present mild kyphotic cervical angles.

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Modified K-Line in Neck Extension Is a Prognostic Indicator of the Surgical Outcome at 5 Years After Cervical Laminoplasty for Cervical Spondylotic Myelopathy

Cited by 8 publications

References 15 publications

Evaluating Changes to the Modified K-Line Using Kinematic MRIs

Evaluating Changes to the Modified K-Line Using Kinematic MRIs

Radiographic Parameters in Cervical Myelopathy

Surgical and Functional Outcomes of Expansive Open-Door Laminoplasty for Patients With Mild Kyphotic Cervical Alignment

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