The relationship between global spinal alignment and pelvic orientation from standing to sitting following pedicle subtraction osteotomy in ankylosing spondylitis patients with thoracolumbar kyphosis
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To investigate the relationship between the spinal sagittal alignment and arc of pelvic motion from standing to sitting in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis following pedicle subtraction osteotomy (PSO).
Materials and Methods
AS patients who underwent PSO for thoracolumbar kyphosis from January 2016 to July 2018 were recruited. EOS standing and sitting images were obtained pre- and postoperatively. Radiographic parameters were measured on the sagittal radiographs, including lumbar lordosis, thoracic kyphosis, pelvic incidence, pelvic tilt, sacral slope, sagittal vertical axis (SVA), spinosacral angle, anterior pelvic plane angle (APPA) and knee flexion angle.
Thirty-six patients were enrolled. From standing to sitting, APPA was increased by a mean of 14.7° (P < 0.001) and 3.0° (P = 0.083) before and after surgery, respectively. The increase in APPA from standing to sitting was correlated with the standing SVA (R = 0.592, P < 0.001) preoperatively. After PSO, the change in APPA was correlated with the change in SSA in both the standing and sitting position (R = 0.381, P = 0.022 and R = 0.667, P < 0.001, respectively). The APPA from standing to sitting was decreased in 11 patients with standing C7 plumb line posterior to the femoral head postoperatively.
In AS patients, pelvic orientation was adjusted by the global spinal alignment. When planning total hip arthroplasty for AS patients, global spinal alignment should be considered to improve the joint stability.
KeywordsAnkylosing spondylitis Thoracolumbar kyphosis Osteotomy Anterior pelvic plane Standing Sitting
This study was funded by the “Six One” Advanced Health Professionals Project of the Key Talents Program of Jiangsu Province (LGY2017001), Jiangsu Provincial Medical Talent (RC2011147) and the Jiangsu Provincial Key Medical Center (YXZXA2016009).
Compliance with ethical standards
All methods were performed in accordance with the relevant guidelines and regulations.
Conflict of interest
Shi-zhou Zhao, Bang-ping Qian, Yong Qiu, Mu Qiao, Zhuo-jie Liu, and Ji-chen Huang declare that they have no conflict of interest.
Research involving human and/or animal participants
This article does not contain any studies with human participants or animals performed by any of the authors.
Informed consent was obtained from all individual participants included in the study.
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