Fig. 1

Schema describing the correction in the two-stage surgery in ASD. (a) preoperative to the 1st stage LLIF surgery (Pre); (b) postoperative following the 1st stage LLIF surgery (M); (c) postoperative following the 2nd stage PCO/PSF surgery (Post); LLIF lateral lumbar interbody fusion, PCO posterior column osteotomy, PSF posterior spinal fusion.