Long-term follow-up study of anterior decompression and fusion for thoracic myelopathy resulting from ossification of the posterior longitudinal ligament

Study Design. This was a retrospective study of the results of anterior decompression and fusion in patients with thoracic myelopathy secondary to ossification of the posterior longitudinal ligament with a minimum follow-up time of 5 years. Objectives. To clarify the effectiveness and limits of anterior decompression and fusion for thoracic ossification of the posterior longitudinal ligament. Summary of Background Data. Posterior decompression for the surgical management of thoracic ossification of the posterior longitudinal ligament has had an uncertain success record. Anterior decompression and fusion have been considered the treatment of choice; however, there are few reports describing the long-term results. Methods. The participants in this investigation were 33 patients whose cases were followed for an average period of 8 years and 2 months. The factors that were investigated included changes in the Japanese Orthopedic Association score and in recovery rates, postoperative complications, and radiographic findings of bone union and progression of ossification of the posterior longitudinal ligament within the area of anterior decompression. Results. Although the recovery rates were relatively stable from 1-5 years after surgery, the rates declined thereafter. The average recovery rate at the final follow-up visit was 53.2%. Postoperative complications included three cases of deterioration of thoracic myelopathy and four cases of extrapleural cerebrospinal fluid leakage. Except for the one case of deterioration of thoracic myelopathy, the remainder of the complications were transient. Conclusions. Anterior decompression and fusion is an effective surgical procedure for thoracic ossification of the posterior longitudinal ligament with good, stable, long- term results; when thoracic ossification of the posterior longitudinal ligament was extensive or coincident with ossification of the intraspinal ligament, however, the results were not as predictable.