En Bloc Resection of Lamina and Ossified Ligamentum Flavum in the Treatment of Thoracic Ossification of the Ligamentum Flavum

OBJECTIVE We performed a retrospective patient chart review to determine the feasibility and safety of en bloc resection of lamina and ossified ligamentum flavum in the treatment of thoracic ossification of ligamentum flavum (OLF). METHODS From January 2000 to June 2006, 36 patients with thoracic OLF underwent en bloc resection of lamina and ossified ligamentum flavum by a burr-grinding technique. The range of resection included one lamina superior and one lamina inferior to the diseased segments. Ossified dura mater was removed if present, and simultaneous repair was carried out. RESULTS The mean preoperative Japanese Orthopedic Association (JOA) score (an evaluation system for thoracic myelopathy with a total score of 11 points) was 5 points (range, 3–9 points). The mean JOA score at the last follow-up visit (mean follow-up period, 3.9 years) was 8.44 points (range, 6–11 points). The range of improvement was from 2 to 6 points, and the mean improvement rate was 60.5% (range, 33.3%–100%). No postoperative aggravation of neurological dysfunction, leakage of cerebrospinal fluid (CSF), wound infection, kyphosis, or recurrence occurred. A CSF cyst found in one patient 3 weeks postoperatively was absorbed automatically after 10 months. CONCLUSION The en bloc resection technique described here is both safe and effective.