Overcorrection of lumbar lordosis for adult spinal deformity with sagittal imbalance: comparison of radiographic outcomes between overcorrection and undercorrection

Purpose To determine the correlation of the difference between postoperative lumbar lordosis (LL) and ideal LL with the sagittal vertical axis (SVA) at the final follow-up in patients with adult spinal deformity (ASD). Methods Fifty-one patients with degenerative lumbar kyphosis (DLK) (mean age 66.5 years) who underwent surgical correction with a minimum 2-year follow-up were evaluated. Based on the difference between postoperative LL and ideal LL using the Korean version of Legaye’s formula, we divided the 51 patients into two groups: overcorrection (degree of postoperative LL > ideal LL) and undercorrection (degree of postoperative LL