OBJECTIVESTo investigate the long-term surgical outcome of thoracic myelopathy caused by the ossification of the ligamentum flavum (OLF) and evaluate the related risk factors.

METHODSForty-four patients who underwent decompressive laminectomy with thoracic OLF between January 1990 and December 2005 and got more than 5 years follow-up were retrospectively reviewed. Among these 44 cases, there were 29 male and 15 female whose ages at operation were 52 years averagely (27-68 years). The 2-year follow-up results and long-term outcomes were classified according to the modified Epstein's standard, and then the rates of excellent or good (REG) were calculated. The correlation between the long-term REG and the patients' ages, durations of symptoms, decompressed levels, and dural leak were analyzed.

RESULTSThe mean follow-up period of these 44 cases was 8.5 years (5-19 years). The REG at 2 years after laminectomy was 77.3% (34/44), while the long-term REG was 65.9% (29/44). There was one case who had suffered from an acute spinal cord injury got a poor post-operative outcome. The other 43 cases had chronic durations, including 22 cases whose pre-operative durations of symptoms were less than 12 months and 21 cases whose durations were equal to or more than 12 months. And the long-term REG of these two groups were 77.3% (17/22) and 57.1% (12/21) respectively (P>0.05). The REG of those cases whose decompression levels were limited in T1-T9 was 78.9% (15/19), while that of those cases whose laminectomy was relevant to thoracolumbar segment (T10-L2) was 58.3% (14/24) (P>0.05). There were 7 cases who had excellent or good short-term results and poor long-term outcomes. The reasons of these changes included coexistence of lumbar spinal stenosis in three cases and the growth of the OLF at the adjacent levels in four cases.

CONCLUSIONSAlthough the short-term results of the decompressive surgery for thoracic OLF is good, the regular long-term follow-up is necessary because the symptoms may reoccur or deteriorate secondary to lumbar spinal stenosis or the growth of OLF at the adjacent levels near former decompressive levels; the duration of symptoms which is more than one year and the decompression levels that is involved to T10-L2 segments are possibly related to the poor long-term outcomes.