Thoracic ligament ossification in patients with cervical ossification of the posterior longitudinal ligaments: tandem ossification in the cervical and thoracic spine.

Abstract

A retrospective investigation of patients who underwent decompressive surgery for cervical ossification of the posterior longitudinal ligament (OPLL). In this study, we would like to introduce a new terminology for the phenomena of coexisting paraspinal ligament ossification in 2 adjacent spinal regions as "tandem ossification." The purpose of this study is to evaluate the incidence and features of tandem ossification in patients with cervical OPLL. Sometimes, OPLL and ossification of the ligamentum flavum (OLF) may coexist in the cervical and thoracic spine on the account of similar pathogenesis. However, there has been only a few previous reports concerning about the incidence of concurrent thoracic ligament ossification in the patients with cervical OPLL. We reviewed the cervicothoracic magnetic resonance imaging (MRI) and computed tomography (CT) images of patients who underwent decompressive surgery for cervical OPLL in our institute during the last 5 years. Total 68 cases of cervical OPLL patients were included. All patients underwent surgical decompression due to cervical myelopathy or myeloradiculopathy. We focus, however, on the presence of thoracic tandem ossification found in 23 of these cases (33.8%); 21 had thoracic OLF, 5 had thoracic OPLL and 3 had both combined. Six of the 23 patients (26.1%) with thoracic tandem ossification had myelopathic symptoms, and required secondary thoracic surgery within 3.3 months (1-7 months) of the original cervical procedures. There were no significant differences in age, sex, cervical OPLL type, or length of cervical OPLL between the patients with and without tandem ossification. Patients having cervical surgery for OPLL should also undergo simultaneous studies of the thoracic spine looking for tandem OPLL and/or OLF. The frequency of tandem lesions in this series was 23 of 68, with 6 requiring subsequent surgery for an evolving thoracic myelopathic deficit.