Research progress on the risk factors, prevention and long-term prognosis of intraoperative sagittaltranslation secondary to ankylosing spondylitis / 中华骨科杂志

ABSTRACT

Sagittal translation(ST) was defined as any measurable sagittal displacement more than 5 mm between the posterior inferior edge of the cranial vertebral body and the posterior superior edge of the caudal body at the osteotomized vertebrae(OV). Ankylosing spondylitis (AS) is a chronic inflammatory disease characterized by enthesitis and heterotopic ossification affecting sacroiliac joints and vertebral column. In the late stage, the poor quality of life caused by inability to lie supine or look straight ahead were the chief reasons for spinal osteotomy. Intraoperative ST secondary to AS thoracolumbar kyphosis contributed to improvement of sagittal vertical axis (SVA) partly. However, severe ST leaded to a huge bony step in front of dura, which was prone to vascular injury, neurologic deficit and cerebrospinal fluid leakage, thus affecting surgical outcomes. Prior research indicated there were significant correlations between intraoperative ST and inappropriate maneuver, the degree of ankylosis, the kyphosis curve pattern and correction, early fracture of the anterior cortex of the OV, excessive or insufficient decancellation of the OV, mismatch between the center of correcting forces and the center of rotation, incorrect application of cantilever technique. The use of anti-ST appliances, intraoperative fluoroscopy and nerve monitoring could prevent the occurrence of ST effectively. For AS patients with ST, relevant measures or decompressive laminectomies could be taken on the basis of neurological function to prevent neurologic deficit. Due to the strong osteogenic ability in AS patients, favorable bony reconstruction and fusion could be available during follow-up after adopting corresponding treatment involving ST. A thorough understanding of mechanism and risk factors of sagittal translation was essentially instructional to spinal surgeons thereby the incidence of intraoperative ST and complications could be decreased.