Surgical Outcomes According to Dekyphosis in Patients with Ossification of the Posterior Longitudinal Ligament in the Thoracic Spine

OBJECTIVE: Ossification of posterior longitudinal ligament (OPLL) in the thoracic spine may cause chronic compressive myelopathy that is usually progressive, and unfavorable by conservative treatment. Although surgical intervention is often needed, the standard surgical method has not been established. Recently, it has been reported that posterior decompression with dekyphosis is effective surgical technique for favorable clinical outcome. The purpose of this study was to evaluate the surgical outcomes in patients with thoracic OPLL according to dekyphosis procedure and to identify predictive factors for the surgical results. METHODS: A total of 25 patients with thoracic OPLL who underwent surgery for myelopathy from May 2004 to March 2017, were retrospectively reviewed. Patients with cervical myelopathy were excluded. We assessed the clinical outcomes according to various surgical approaches. The modified Japanese orthopedic association (JOA) scores for the thoracic spine (total, 11 points) and JOA recovery rates were used for investigating surgical outcomes. RESULTS: Of the 25 patients, 10 patients were male and the others were female. The mean JOA score was 6.7±2.3 points preoperatively and 8.8±1.8 points postoperatively, yielding a mean recovery rate of 53.8±31.0%. The mean patients’ age at surgery was 52.4 years and mean follow-up period was 40.2 months. According to surgical approaches, seven patients underwent anterior approaches, 13 patients underwent posterior approaches, five patients underwent combined approaches. There was no significant difference of the surgical outcomes related with different surgical approaches. Age (≥55 years) and high signal intensity on preoperative magnetic resonance (MR) image in the thoracic spine were significant predictors of the lower recovery rate after surgery (p<0.05). Posterior decompression with dekyphosis procedure was related to the excellent surgical outcomes (p=0.047). Dekyphosis did not affect the complication rates. CONCLUSION: In this study, our result elucidated that old age (≥55 years) and presence of intramedullary high signal intensity on preoperative MR images were risk factors related to poor surgical outcomes. In the meanwhile, posterior decompression with dekyphosis affected favorable clinical outcome. Posterior approach with dekyphosis procedure can be a recommendable surgical option for favorable results.