Prevalence and Distribution of Ossified Lesions in the Whole Spine of Patients with Cervical Ossification of the Posterior Longitudinal Ligament A Multicenter Study (JOSL CT study).

Takashi Hirai,Masahiko Abematsu,Yoshiharu Kawaguchi,Shunsuke Fujibayashi,Toshitaka Yoshii,Akio Iwanami,Haruo Kanno,Yukihiro Matsuyama,Shiro Imagama,Kanichiro Wada,Masashi Yamazaki,Atsushi Okawa,Hiroshi Ozawa,Masahiko Watanabe,Hirotaka Haro,Katsushi Takeshita,Kei Watanabe,Kanji Mori,Masaya Nakamura,Morio Matsumoto,Kazuhiro Takeuchi,Masao Koda,Takatsugu Yamada

doi:10.1371/journal.pone.0160117

Abstract

Ossification of the posterior longitudinal ligament (OPLL) can cause severe and irreversible paralysis in not only the cervical spine but also the thoracolumbar spine. To date, however, the prevalence and distribution of OPLL in the whole spine has not been precisely evaluated in patients with cervical OPLL. Therefore, we conducted a multi-center study to comprehensively evaluate the prevalence and distribution of OPLL using multi-detector computed tomography (CT) images in the whole spine and to analyze what factors predict the presence of ossified lesions in the thoracolumbar spine in patients who were diagnosed with cervical OPLL by plain X-ray. Three hundred and twenty-two patients with a diagnosis of cervical OPLL underwent CT imaging of the whole spine. The sum of the levels in which OPLL was present in the whole spine was defined as the OP-index and used to evaluate the extent of ossification. The distribution of OPLL in the whole spine was compared between male and female subjects. In addition, a multiple regression model was used to ascertain related factors that affected the OP-index. Among patients with cervical OPLL, women tended to have more ossified lesions in the thoracolumbar spine than did men. A multiple regression model revealed that the OP-index was significantly correlated with the cervical OP-index, sex (female), and body mass index. Furthermore, the prevalence of thoracolumbar OPLL in patients with a cervical OP-index ≥ 10 was 7.8 times greater than that in patients with a cervical OP-index ≤ 5. The results of this study reveal that the extent of OPLL in the whole spine is significantly associated with the extent of cervical OPLL, female sex, and obesity.

Highlights

Since first being documented in 1838 [1], ossification of the posterior longitudinal ligament (OPLL) has been recognized as a heterotopic bone formation in the posterior longitudinal ligament of the spine
Because thoracolumbar OPLL often coexists with cervical OPLL and sometimes causes severe and irreversible paralysis [16], it is clinically important to recognize thoracolumbar OPLL and clarify the factors associated with the extent of OPLL in the whole spine
The current study revealed that 56.2% of patients with cervical OPLL had coexisting ossified lesions in the thoracolumbar spine

Summary

Introduction

Since first being documented in 1838 [1], ossification of the posterior longitudinal ligament (OPLL) has been recognized as a heterotopic bone formation in the posterior longitudinal ligament of the spine. Various studies have documented the incidence of cervical OPLL. A previous single-institution CT study demonstrated that patients with cervical OPLL had a high incidence of OPLL in the thoracolumbar spine [9]. It has been well documented that prognosis and surgical outcomes are worse in patients with multiple-regional OPLL than in patients with cervical lesions alone [15]. Because thoracolumbar OPLL often coexists with cervical OPLL and sometimes causes severe and irreversible paralysis [16], it is clinically important to recognize thoracolumbar OPLL and clarify the factors associated with the extent of OPLL in the whole spine

Methods

Results

Conclusion