Can intraoperative T1 tilt predict postoperative shoulder imbalance in patients with Lenke 2 adolescent idiopathic scoliosis?: a retrospective study in Japan.

STUDY

DESIGN

Retrospective cohort study.

PURPOSE: To evaluate whether intraoperative changes in T1 tilt can predict the development of postoperative shoulder imbalance (PSI) in patients with Lenke type 2 adolescent idiopathic scoliosis (AIS).

OVERVIEW OF LITERATURE: Multiple factors have been associated with PSI, but few studies have specifically investigated intraoperative radiographic predictors, such as changes in T1 tilt, in patients with Lenke type 2 AIS.

METHODS

Fifty patients (45 females, five males) who underwent posterior corrective fusion surgery for Lenke type 2 AIS with at least 2 years of follow-up were included. Radiographic parameters and health-related quality of life were evaluated preoperatively, 1 week postoperatively, and at final follow-up. Intraoperative T1 tilt and upper instrumented vertebra (UIV) tilt were measured in the prone position before and after correction. PSI was defined as radiographic shoulder height (RSH) greater than 15 mm at 1 week postoperatively. Patients were classified into PSI and non-PSI groups. Intergroup comparisons were conducted using the Mann-Whitney U test or chisquare test. Correlations of intraoperative changes in T1 tilt (ΔT1) and UIV tilt (ΔUIV) with changes in RSH (ΔRSH) and clavicle angle (ΔCA) were analyzed.

RESULTS

Twelve patients (24.0%) had PSI at 1 week postoperatively, which persisted in five patients (10.0%) at final follow-up. Intraoperative ΔT1 and ΔUIV were significantly correlated with ΔRSH (R =0.613, p <0.001; R =0.435, p =0.002) and ΔCA (R =0.453, p =0.002; R =0.383, p =0.007). In the PSI group, ΔRSH was strongly correlated with ΔT1 (R =0.678, p =0.015).

CONCLUSIONS

Minimizing intraoperative changes in T1 tilt may help reduce the risk of PSI in Lenke type 2 AIS.