Summary of Background Data
Ossification of the posterior longitudinal ligament (OPLL) is an ectopic bone formation in the ligament tissue of the spine, causing myelopathy as a result of chronic pressure on the spinal cord and nerve roots. It has been further categorized into 4 types, that is, segmental, continuous, mixed types, and the other types; however, differences in the detail of the progression in the ossification and natural history of the disease among these types have not been clarified.
To find out the systemic feature, which has relevance to the disease state of OPLL.
To characterize these types, we conducted an investigation of cardiovascular factors [blood pressure, blood loss during or after surgery, bleeding time, coagulation factors (prothrombin test, activated partial thromboplastin time)] among OPLL, cervical spondylotic myelopathy (CSM), and subtypes of OPLL (continuous, mixed, segmental, and the other types).
Retrospective case series.
These parameters of patients with cervical spondylotic myelopathy were used as a control (CSM patients). Although there was no significant difference in bleeding time and coagulation factors, blood loss after surgery of OPLL patients was significantly higher than that of CSM patients (P<0.01). Furthermore, blood loss of patients with continuous type of ossification was significantly higher (P<0.05) than that of patients with segmental type of ossification, which was nearly equal to that of CSM patients. Blood loss of patients with mixed type of ossification showed the value of the middle of segmental and continuous types.