Dynamic K-Line Status and Surgical Outcomes in Multilevel Cervical OPLL: A Multicenter Comparative Study

Area of Science:

• Neurosurgery
• Orthopedic Surgery
• Spinal Surgery

Background:

• Multilevel cervical ossification of the posterior longitudinal ligament (OPLL) presents complex surgical challenges.
• Dynamic K-line status is a crucial factor influencing surgical outcomes in cervical OPLL.
• Predicting neurological recovery is essential for optimizing treatment strategies.

Purpose of the Study:

• To evaluate clinical and radiological outcomes of surgical interventions for cervical OPLL stratified by dynamic K-line status.
• To identify predictors of neurological recovery in patients with multilevel cervical OPLL.
• To compare the efficacy of anterior cervical discectomy and fusion (ACDF), laminoplasty (LP), and laminectomy with fusion (LF).

Main Methods:

• Analysis of 535 patients with multilevel cervical OPLL undergoing ACDF, LP, or LF with ≥24 months follow-up.
• Classification into three groups based on dynamic K-line status (neutral and flexion).
• Multivariate regression and inverse probability of treatment weighting (IPTW) analysis to identify predictors and reduce bias.

Main Results:

• Progressive dynamic K-line negativity correlated with cervical kyphosis, higher canal occupation, and poorer recovery.
• ACDF demonstrated superior adjusted neurological recovery across all K-line subgroups after IPTW.
• LF showed better recovery than LP in patients with negative neutral or flexion K-lines; larger preoperative and postoperative FK-line distance increases predicted better outcomes.

Conclusions:

• Dynamic K-line stratification is a valuable prognostic tool for multilevel cervical OPLL.
• ACDF is the most effective surgical option regardless of K-line status.
• LF is recommended over LP for patients with latent or fixed negative FK-line status to enhance neurological recovery.