DOI: 10.1097/md.0000000000040675 ISSN: 0025-7974

Effect of K-line (−) or (+) on surgical outcomes in cervical ossification of the posterior longitudinal ligament: A systematic and meta-analysis

Yongping Wang, Xiao Chen, Yuan Luo, Chang Chen, Ran Cui
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Background:

To conduct a systematic review and meta-analysis assessing the influence of K-line status on postoperative clinical outcomes in patients with cervical posterior longitudinal ligament ossification (OPLL).

Methods:

We searched PubMed, Embase, OVID, Cochrane Library, and Web of Science databases for English-language literature related to K-line and OPLL up to June 7, 2024. The study underwent rigorous selection, quality assessment, and data extraction, followed by meta-analysis using Review Manager 5.3 and Stata 17.0 software. This study has been registered with the international PROSPERO registry (registration number: CRD42024558578).

Results:

Seventeen articles encompassing 1247 patients were included. The meta-analysis revealed that patients with a positive K-line (K-line (+)) exhibited significantly enhanced Japanese Orthopaedic Association score recovery rate (mean differences [MD] = 19.28, 95% confidence interval [CI]: 12.28–26.28, P < .00001), Japanese Orthopaedic Association score (MD = 1.51, 95% CI: 0.64–2.37, P = .0007), C2-C7 Cobb angle (MD = 6.45, 95% CI: 3.73–9.17, P < .00001), alongside reduced occupation ratio (MD = −7.67, 95% CI: −10.86 to −4.49, P < .00001), C2-C7 sagittal vertical axis (MD = −6.18, 95% CI: −8.36 to −3.99, P < .00001), and neck disability index (MD = −1.85, 95% CI: −3.18 to −0.52, P = .006) at final follow-up compared to those with a negative K-line (K-line (−)). No significant differences were observed in postoperative complication rates (odds ratio = 1.15, 95% CI: 0.41–3.20, P = .79), final follow-up visual analog scale scores (MD = −0.10, 95% CI: −0.80 to 0.59, P = .77), or T1 slope (MD = 2.66, 95% CI: −0.20 to 5.52, P = .07) between the 2 groups.

Conclusion:

A positive preoperative K-line (K-line (+)) is a better predictor of prognosis and is associated with improved clinical outcomes in patients with multi-segmental cervical OPLL compared to a negative K-line (K-line (−)).

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