Microsurgical resection of ossification of the posterior longitudinal ligament in the thoracic spine via the transthoracic approach without spinal fusion: case series and technical note

OBJECTIVE Surgical management of thoracic ossification of the posterior longitudinal ligament (OPLL) remains challenging because of the anatomical complexity of the thoracic spine and the fragility of the thoracic spinal cord. Several surgical approaches have been described, but it remains unclear which of these is the most effective. The present study describes the microsurgical removal of OPLL in the middle thoracic level via the transthoracic anterolateral approach without spinal fusion, including the surgical outcome and operative tips. METHODS Between 2002 and 2017, a total of 8 patients with thoracic myelopathy due to OPLL were surgically treated via the transthoracic anterolateral approach without spinal fusion. The surgical techniques are described in detail. Clinical outcome, surgical complications, and the pre-and postoperative thoracic kyphotic angle were assessed. RESULTS The mean patient age at the time of surgery was 55 years (range 47-77 years). There were 5 women and 3 men. The surgically treated levels were within T3-9. The clinical symptoms and Japanese Orthopaedic Association (JOA) score improved postoperatively in 7 cases, but did not change in 1 case. The mean JOA score increased from 6.4 preoperatively to 7.5 postoperatively (recovery rate 26%). Intraoperative CSF leakage occurred in 4 cases, and was successfully treated with fibrin glue sealing and spinal drainage. The mean follow-up period was 82.6 months (range 15.3-169 months). None of the patients had deterioration of the thoracic kyphotic angle. CONCLUSIONS Anterior decompression is the logical and ideal procedure to treat thoracic myelopathy caused by OPLL on the concave side of the spinal cord; however, this procedure is technically demanding. Microsurgery via the transthoracic anterolateral approach enables direct visualization of the thoracic ventral ossified lesion. The use of microscopic procedures might negate the need for bone grafting or spinal instrumentation.