Clinical characteristics and surgical outcome of the symptomatic ossification of ligamentum flavum at the thoracic level with combined lumbar spinal stenosis

Study design Retrospective study. Objective To identify the clinical significance of coexistence of lumbar spinal stenosis (LSS) with thoracic ossification of ligamentum flavum (OLF), and to study the surgical outcome of the thoracic OLF patients with or without LSS. Summary of background data The OLF at the thoracic level (thoracic OLF) is a rare disease that causes acquired thoracic spinal canal stenosis. Thoracic OLF is frequently combined with other spinal disorders, such as LSS, and it is not uncommon for thoracic OLF to be misdiagnosed as LSS, resulting in delayed diagnosis. However, clinical impacts of the coexistence of LSS with thoracic OLF remain unknown. Methods In the present study, 36 patients who underwent posterior decompression for OLF-induced thoracic myelopathy were retrospectively reviewed, and the adverse influence of the copresence of LSS with thoracic OLF was studied with regard to clinical features such as clinical symptoms and surgical outcome. Results Out of 36 patients, 18 patients had LSS (combined group: C-group), and the remaining 18 patients had thoracic OLF only (thoracic group: T-group). No significant inter-group differences were found in terms of gender, age, follow-up period, and preoperative duration of symptoms. Regarding the etiology of LSS in the C-group, 12 cases had degenerative LSS, two cases had lumbar OLF, one case had degenerative LSS with lumbar OLF, one case had had degenerative LSS with lumbar OPLL, and two cases had traumatic LSS due to lumbar kyphosis after vertebral fracture. Clinical examination revealed that the T-group was significantly more likely to demonstrate Achilles hyper-reflexia, while the C-group was significantly more likely to demonstrate Achilles hypo-reflexia. The mean preoperative and postoperative JOA scores were not statistically different between the two groups. However, the mean recovery rate of the JOA score was 17.3% in the C-group, and 30.4% in the T-group. Statistical analysis revealed that the recovery rate of the C-group was significantly lower than that of the T-group. Conclusion Thoracic OLF with LSS will show a more severe clinical manifestation than that without LSS. In this study, we clearly indicated that the coexisting LSS in thoracic OLF will have adverse effects on the surgical results in thoracic OLF.