Progression of Cervical Ossification of the Posterior Longitudinal Ligament: A Systematic Review and Meta-Analysis of Risk Factors, Surgical Approaches, and Reoperation Rates.
BACKGROUND Cervical ossification of the posterior longitudinal ligament (OPLL) frequently progresses despite decompression surgery, leading to recurrent myelopathy. This meta-analysis aims to quantify risk factors for OPLL progression, compare surgical strategies, and determine the pooled reoperation rate due to symptomatic progression. METHODS Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, 26 high-quality studies comprising 1929 patients were included. Standardized mean differences (SMDs) and odds ratios (ORs) with 95% confidence intervals were calculated to assess risk factors, and all of the analyses were done with a random-effects model. A network meta-analysis using a random-effects model was conducted to compare surgical approaches, utilizing laminoplasty (LP) as the reference node. RESULTS Significant demographic risk factors for OPLL progression included younger age (SMD: -0.68, P < 0.001) and higher body mass index (SMD: 0.43, P < 0.001). Radiographically, progression was strongly driven by longer preoperative OPLL (SMD: 0.42, P = 0.003), a lower preoperative cervical range of motion (SMD: -0.30, P = 0.039), and OPLL at the C3 level (OR: 7.04, P < 0.001). Mixed-type OPLL nearly tripled the progression risk (OR: 2.94, P < 0.001), whereas segmental-type was highly protective (OR: 0.13, P < 0.001).The network meta-analysis demonstrated that motion-preserving posterior surgeries were associated with higher rates of OPLL progression. Compared with LP, anterior surgery provided the greatest reduction in progression risk (OR 0.28, P < 0.001), followed by laminectomy with fusion (OR 0.42, P < 0.001). Direct pairwise comparisons similarly confirmed that laminectomy with fusion significantly reduced the likelihood of progression compared with LP (OR 0.44, P = 0.002). Nonsurgical management was also associated with lower odds of progression; however, this finding should be interpreted with caution due to potential confounding by indication. Additionally, the pooled long-term reoperation rate due to neurological deterioration from OPLL progression was 6.1% (95% confidence interval 2.9%-10.2%) over a mean follow-up of 72.6 ± 63.7 months. CONCLUSIONS OPLL progression is statistically predictable, driven by younger age, higher body mass index, reduced cervical range of motion, and mixed-type morphology. Because anterior and fusion procedures were associated with lower progression rates compared with LP, these approaches should be considered in high-risk patients; however, these findings should be interpreted with caution given the heterogeneity across included studies. CLINICAL RELEVANCE For patients with high-risk profiles (eg, mixed-type OPLL), fusion or anterior decompression should be strongly considered over LP. When laminoplasty is used in high-risk patients, they should be advised on the necessity of long-term surveillance. LEVEL OF EVIDENCE: 3