The purpose of this study was to provide the first evidence for the influence of an ossified anterior longitudinal ligament (OALL) on the clinical features and surgical outcomes in an ossified ligamentum flavum (OLF) in the thoracic region.
Sixty-three patients who underwent surgery for a 1-level thoracic OLF were identified, and preoperative symptoms, severity of symptoms and myelopathy, disease duration, MR imaging and CT findings, surgical procedure, intraoperative findings, complications, and postoperative recovery were investigated in these patients. Entities of OALLs were found on sagittal CT images to be adjacent to or at the same vertebral level as the OLF were classified into 4 types: no discernible type (Type N), one-sided (Type O), discontinuous (Type D), and continuous (Type C).
The duration of symptoms was especially long for Types D and C OALLs. Patients with Type D OALLs had a significantly worse percentage of recovery, as well as worse preoperative JOA scores.
The authors' results showed that a Type D OALL had strong associations with preoperative severity of symptoms and surgical outcomes. These findings may allow surgeons to determine the severity of preoperative symptoms and the probable surgical outcomes from the OALL classifications. Moreover, surgery with instrumentation for Type D OALLs may produce better surgical outcomes.
Abbreviations used in this paper: ALL = anterior longitudinal ligament; CSM = cervical spondylosis myelopathy; DISH = diffuse idiopathic skeletal hypertrophy; JOA = Japanese Orthopaedic Association; OALL = ossified ALL; OLF = ossified ligamentum flavum; OPLL = ossified posterior longitudinal ligament.
AizawaTSatoTSasakiHKusakabeTMorozumiNKokubunS: Thoracic myelopathy caused by ossification of the ligamentum flavum: clinical features and surgical results in the Japanese population. J Neurosurg Spine5:514–5192006
GuoJJLukKDKarppinenJYangHCheungKM: Prevalence, distribution, and morphology of ossification of the ligamentum flavum: a population study of one thousand seven hundred thirty-six magnetic resonance imaging scans. Spine (Phila Pa 1976)35:51–562010
HirabayashiKMiyakawaJSatomiKMaruyamaTWakanoK: Operative results and postoperative progression of ossification among patients with ossification of cervical posterior longitudinal ligament. Spine (Phila Pa 1976)6:354–3641981
MaigneJYAyralXGuérin-SurvilleH: Frequency and size of ossifications in the caudal attachments of the ligamentum flavum of the thoracic spine. Role of rotatory strains in their development An anatomic study of 121 spines. Surg Radiol Anat14:119–1241992
MiyakoshiNShimadaYSuzukiTHongoMKasukawaYOkadaK: Factors related to long-term outcome after decompressive surgery for ossification of the ligamentum flavum of the thoracic spine. J Neurosurg99:3 Suppl251–2562003
OgaMMashimaTIwakumaTSugiokaY: Dysphagia complications in ankylosing spinal hyperostosis and ossification of the posterior longitudinal ligament. Roentgenographic findings of the developmental process of cervical osteophytes causing dysphagia. Spine (Phila Pa 1976)18:391–3941993
YamazakiMMochizukiMIkedaYSodeyamaTOkawaAKodaM: Clinical results of surgery for thoracic myelopathy caused by ossification of the posterior longitudinal ligament: operative indication of posterior decompression with instrumented fusion. Spine (Phila Pa 1976)31:1452–14602006
YayamaTUchidaKKobayashiSKokuboYSatoRNakajimaH: Thoracic ossification of the human ligamentum flavum: histopathological and immunohistochemical findings around the ossified lesion. J Neurosurg Spine7:184–1932007