Surgical strategies for ossified ligamentum flavum associated with dural ossification in thoracic spinal stenosis

We describe two surgical strategies for treating thoracic spinal stenosis (TSS) with ossification of the ligamentum flavum (OLF) and dural ossification (DO), and discuss their postoperative efficacy. From January 2004 to June 2008, 147 patients underwent TSS surgery. Thirty three of those with intraoperative evidence of OLF and DO were included in the present study. Based on the different intraoperative treatment of the dura, these 33 patients were divided into two groups: Group A, 17 patients who had their dura slit and the ossification excised, and Group B, 16 patients treated by floating the ossified dura by thinning it with a drill. All patients underwent outpatient follow-up. Pre- and postoperative Japanese Orthopaedic Association (JOA) scores and recovery rates were evaluated. The mean follow-up period was 42 months. The incidence of DO with OLF in TSS was 22%. At 1 year follow-up, the mean JOA score improved from 5.12 ± 1.17 to 6.94 ± 0.90 in Group A and from 5.25 ± 1.34 to 7.13 ± 1.41 in Group B. Additionally, the mean JOA score improved from 5.18 ± 1.24 to 7.03 ± 1.16 in TSS patients with DO and from 5.52 ± 1.21 to 7.21 ± 1.18 in TSS patients without DO. The increased cross-sectional area of the pre- and postoperative dural sac at the level of stenosis suggested that decompression was complete. Both decompression methods are feasible for curing TSS with OLF and DO. Moreover, slitting the dura for ossified dura and ligamentum flavum removal to relax the spinal cord is a safe and reliable method. Even though it increased the surgical difficulties and risks, DO did not affect postoperative neurological recovery.