Changes in the Adjacent Segment After Thoracolumbar Posterior Instrumentation and Fusion Surgery in Thoracolumbar Junction Fractures

Abstract

Introduction: The incidence of adjacent segment degeneration or disease is increasing as the spine surgeries increase. There have been many articles on risk factors causing adjacent segment change after lumbar fusion surgery, but few articles have been released on the topic in thoracolumbar spine. Therefore, we intended to evaluate the change of adjacent segment after posterior instrumentation and fusion in thoracolumbar spine. Material(s) and Method(s): From 2000 to 2013, fifty patients were reviewed retrospectively. The patients underwent posterior instrumentation and fusion due to thoracolumbar fracture and were able to follow up more than 2 years. To evaluate the change of adjacent segment, postoperative sagittal angle, disc height and disc angle of adjacent segment were compared with those at the last follow up. We divided the patients into two groups according to age (more or less than 50 years), laminectomy, fusion levels (2 levels or more than 3 levels) and compared the radiologic parameters between groups. Result(s): The male patients were 36 and the female patients were 14. The average age of the patients was 45.6 years and the mean follow up was 4.3 years. There were no cases of adjacent segment disease. The mean kyphotic sagittal angle progression was 6.8degree (P < .05), but the angle of adjacent segment disc did not show significant change between preoperative and last followup. The change of disc height of proximal adjacent segment was 0.3mm and 0.5mm of disc height in distal adjacent segment (P < .05). Laminectomy did not make significant difference on the change of adjacent segment, but in the group age less than 50 years, the angle of adjacent disc decreased significantly, 0.8degree in proximal adjacent disc and 0.5degree in distal adjacent disc (P < .05). There were no significant radiologic changes as the fusion levels is increased. Conclusion(s): Adjacent segment degeneration or disease after lumbar fusion surgery is not applied to the adjacent segment of thoracolumbar spine. These results are attributed to proximal level of fixation. Mobile segment of lumbar spine may make this difference rather than the instrumentation and fusion procedure itself.