Anterior decompression for myelopathy resulting from thoracic ossification of the posterior longitudinal ligament

Study Design. A retrospective study was conducted to investigate the anterior decompression and fusion of 12 patients with thoracic ossification of the posterior longitudinal ligament. Objective. To evaluate the effect of myelopathy management in which the thoracic ossification of the posterior longitudinal ligament is removed. Summary and Background Data. Very few reports have described operative treatments for thoracic ossification of the posterior longitudinal ligament. The condition is extremely rare, even in Japan. Consequently, operative procedures for myelopathy resulting this disorder have not been established. Methods. This study involved 12 patients with thoracic ossification of the posterior longitudinal ligament. All the patients underwent direct removal of the ossification and spinal fusion using an anterior approach. A scapula-releasing technique was used in five patients who had major ossification of the posterior longitudinal ligament at Th4. The follow-up period ranged from 2.5 to 10 years (mean, 6.5 years). The clinical effect of the decompression was evaluated with a Japanese Orthopedic Association score for cervical myelopathy. The efficacy of the decompression was determined by postoperative computed tomography scan. Results. Complete removal of the ossification was achieved in eight patients. In four patients, however, residual ossification was noted. The Japanese Orthopedic Association score before the operation ranged from 4 to 7 points (mean, 5.3 +/- 0.4 points). It showed a change 3 months after the operation, ranging from 1 to 8 points (mean, 6.9 +/- 0.5 points). At 1 year after the operation, it had changed to a range of 1 to 10 points (mean, 7.2 +/- 0.6 points). At the final consultation, it had changed further to arrange of 1 to 10 points (mean, 6.9 0.5 points). Patients whose ossification was not completely removed showed severe or minor postoperative deterioration. Conclusions. Total removal of the ossification might be required to manage severe myelopathy in patients with thoracic ossification of the posterior longitudinal ligament. Complete removal of the ossification gave good results in eight patients. Patients whose ossification of the posterior longitudinal ligament had not been completely removed, however, had a poor outcome.