Clinical results of surgery for thoracic myelopathy caused by ossification of the posterior longitudinal ligament: operative indication of posterior decompression with instrumented fusion.

STUDY DESIGN: This retrospective study was conducted to investigate the clinical outcomes of several surgical procedures for thoracic myelopathy caused by ossification of the posterior longitudinal ligament (OPLL).

OBJECTIVE: To evaluate the effect of myelopathy treatment and safety of posterior decompression with instrumented fusion.

SUMMARY OF BACKGROUND DATA: Many different surgical procedures have been used for the treatment of thoracic OPLL. However, the possibility of postoperative paraplegia remains a major risk, and consistent protocols and procedures for surgical treatment of thoracic OPLL have also not been established.

METHODS: A total of 51 patients who underwent surgery for thoracic OPLL were classified into 3 groups: (1) posterior decompression group (18 patients), which included 12 who underwent laminectomy and 6 who underwent cervicothoracic laminoplasty; (2) OPLL extirpation group (16 patients), which included 4 who underwent anterior decompression through thoracotomy and 12 who underwent anterior decompression through the posterior approach; and (3) posterior decompression and fusion group (17 patients), all of whom underwent laminectomy with posterior instrumented fusion. In each group, the Japanese Orthopedic Association score was used to evaluate thoracic myelopathy, and the recovery rate calculated 1 year after surgery and at final examination.

RESULTS: Mean recovery rate at final follow-up was 41.9% in the posterior decompression group, 62.1% in the OPLL extirpation group, and 59.3% in the posterior decompression and fusion group. Postoperative paralysis occurred in 3 patients in the posterior decompression group and in 3 in the OPLL extirpation group. In the OPLL extirpation group, leakage of cerebrospinal fluid occurred in 8 patients and hydrothorax in 2. Late neurologic deterioration occurred in 7 patients in the posterior decompression group. There were no cases of postoperative paralysis or late neurologic deterioration in the posterior decompression and fusion group.

CONCLUSIONS: A considerable degree of neurologic recovery was obtained by posterior decompression with instrumented fusion, despite the anterior impingement of the spinal cord by OPLL remaining. In addition, the rate of postoperative complications was extremely low with this procedure. We recommend that 1-stage posterior decompression and instrumented fusion be selected for patients in whom the spinal cord is severely damaged before surgery and/or when extirpation of OPLL is associated with increased risk.