Ossification of the Posterior Longitudinal Ligament of the Cervical Spine in 3161 Patients

In Brief Study Design. A cross-sectional study. Objective. To examine the prevalence of ossification of the posterior longitudinal ligament (OPLL) and ossification of the nuchal ligament (ONL) of the cervical spine in the San Francisco area. Summary of Background Data. The prevalence of OPLL and ONL is unknown in the non-Asian population. Methods. This computed tomography–based cross-sectional study assessed the prevalence of OPLL and ONL within the cervical spine of patients treated at a level 1 trauma center between 2009 and 2012. The prevalence of both OPLL and ONL was compared between racial groups. Results. Of the 3161 patients (mean age, 51.2 ± 21.6 yr; 66.1% male), there were 1593 Caucasians (50.4%), 624 Asians (19.7%), 472 Hispanics (14.9%), 326 African Americans (10.3%), 62 Native Americans (2.0%), and 84 Others (2.7%). The prevalence of cervical OPLL was 2.2% (95% confidence interval [CI]: 1.7–2.8). The adjusted prevalence was 1.3% in Caucasian Americans (95% CI: 0.7–2.3), 4.8% in Asian Americans (95% CI: 2.8–8.1), 1.9% in Hispanic Americans (95% CI: 0.9–4.0), 2.1% in African Americans (95% CI: 0.9–4.8), and 3.2% in Native Americans (95% CI: 0.8–12.3). The prevalence of OPLL in Asian Americans was significantly higher than that in Caucasian Americans (P = 0.005). ONL was detected in 346 patients and the prevalence was 10.9% (95% CI: 10.0–12.0). The adjusted prevalence of ONL was 7.3% in Caucasian Americans (95% CI: 5.8–9.3), 26.4% in Asian Americans (95% CI: 21.9–31.5), 7.4% in Hispanic Americans (95% CI: 5.2–10.5), 2.5% in African Americans (95% CI: 1.2–4.9), and 25.8% in Native Americans (95% CI: 16.5–37.5). ONL was significantly more common in Asian Americans than in Caucasian Americans, Hispanic Americans, and African Americans (P = 0.001). Conclusion. This study also demonstrated that OPLL and ONL were significantly more common in Asian Americans than in Caucasian Americans. Level of Evidence: 3 In the San Francisco area, based on computed tomography, the overall prevalence of cervical ossification of the posterior longitudinal ligament was 2.2% (95% confidence interval [CI]: 1.7–2.8) and the prevalence of ossification of the nuchal ligament was 10.9% (95% CI: 10.0–12.0).