Introduction:

To determine potential risk factors for postoperative coronal imbalance following posterior osteotomy for adult scoliosis.

Materials and methods:

A total of 74 patients underwent osteotomy for rigid adult lumbar scoliosis. A group of 20 patients with postoperative coronal imbalance was identified. Clinical data and surgical strategies were compared to determine the risk factors, including age, gender, etiology, Cobb angle, preoperative coronal balance distance, direction of preoperative imbalance, T1 tilt, tilt of upper instrumented vertebra (UIV), UIV translation, location of UIV (T6 above or below), fusion to L5 or S1, lower instrumented vertebra (LIV) tilt, LIV rotation, screw density, osteotomy procedure (PSO or SPOs) and use of iliac screws.

Results:

Comparison between patients with and without postoperative coronal imbalance showed that postoperative coronal imbalance occurred in older patients and those with degenerative scoliosis as the etiology, UIV above T6, preoperative LIV rotation, preoperative LIV tilt and preoperative coronal imbalance towards the convex side and who underwent Smith-Petersen osteotomy. All seven parameters were included in the logistic regression analysis. UIV above T6 (P = 0.010), LIV rotation (P = 0.012) and preoperative coronal imbalance towards the convex side (P = 0.005) were identified as risk factors for postoperative coronal imbalance after osteotomy.

Conclusions:

Patients with preoperative coronal imbalance towards the convex side (UIV above T6) and LIV rotation were more likely to develop coronal imbalance than those without risk factors. Older patients and those with degenerative scoliosis were also at a relatively higher risk of postoperative coronal imbalance.