Postoperative Progression of Cervical Ossification of Posterior Longitudinal Ligament: A Systematic Review

The purpose of this study was to provide a systematic and comprehensive review of the existing literature regrading postoperative ossification of posterior longitudinal ligament (OPLL) progression.

Using the PRISMA guidelines, we conducted an exhaustive review of electronic databases. Potential articles were screened and related information was extracted and analyzed. Twenty-four articles with low-quality evidence were included in the review. The findings of the literature review were divided into several groups: the relationship of surgery to OPLL progression; incidence and risk factors; timing and process of OPLL progression; the effect of additional instrumentation on progression; and neurologic deterioration related with progression.

There was no definitive conclusion for whether surgery could accelerate OPLL progression compared with the natural course. The incidence of postoperative OPLL progression was reported from 3.3% to 74.5%. Younger age, involvement of multiple levels and mixed or continuous types are recognized as risk factors. OPLL could progress transversely and longitudinally and progression in length appeared more significant than progression in thickness. Although radiologic OPLL progression was observed significantly more frequently after laminoplasty than after fusion surgery, whether additional instrumented fusion could suppress progression needs further research. Radiographic progression of OPLL did not positively correspond with neurologic deterioration.

The lack of high-level evidence makes it difficult to draw definite conclusions and further research and long-term follow-up clinical studies are needed to better understand postoperative OPLL progression.