Effect of position on lumbar lordosis in patients with adult spinal deformity.

OBJECTIVEThe purpose of this study was to evaluate the effect of position on lumbar lordosis (LL) in adult spinal deformity (ASD) patients.METHODSThe authors evaluated the radiographic data of ASD patients who underwent posterior corrective fusion surgery from the thoracic spine to L5, S1, or the ilium for the treatment of ASD of the lumbar spine. The spinopelvic parameters were measured in the standing position preoperatively. LL was also evaluated in the supine position preoperatively and in the prone position on the surgical frame. Changes in LL were compared between groups.RESULTSEighty-five patients were included. The average LL in standing, supine, and prone positions was 11.8°, 24.3°, and 24.0°, respectively. LL increased significantly from standing to supine or prone position (p < 0.001). In 80 patients (94.1%), the difference between supine LL and prone LL was within 5°. Change in LL from standing to prone position was significantly higher in the severe deformity group.CONCLUSIONSThe lordotic effect of intraoperative prone positioning was remarkable in patients with severe deformities. LL in the supine position was approximately the same as that in the prone position. Therefore, assessing preoperative supine lateral lumbar radiographs enables one to plan corrective spinal surgeries in ASD patients.