A Novel Method for Predicting Ideal Postoperative Upper Instrumented Vertebra Tilt to Prevent Lateral Shoulder Imbalance after Scoliosis Correction Surgery

Abstract

Lateral shoulder imbalance (LSI) is reflected radiologically by the clavicle angle (CA). How to achieve postoperative lateral shoulder balance (LSB) after scoliosis correction surgery remains unclear. In the current study, by using the preoperative upper instrumented vertebra (UIV) tilt, the CA, the flexibility between T1 and the UIV, and the ideal postoperative UIV tilt was predicted based on the following formula: ideal postoperative UIV tilt = preoperative UIV tilt—the flexibility between T1 and UIV—preoperative CA. The reliability of the formula was verified through a retrospective analysis, and 76 scoliosis patients were enrolled. The feasibility of this method was verified through a prospective analysis, and 13 scoliosis patients were enrolled. In the retrospective study, there was a significant correlation between the difference in the actual and ideal postoperative UIV tilt values and the postoperative CA, with correlation coefficients in the whole, LSI, and LSB groups of 0.981, 0.982, and 0.953, respectively (p < 0.001). In the prospective study, all patients achieved satisfactory LSB. Using the formula preoperatively to predict an ideal postoperative UIV tilt and controlling the intraoperative UIV tilt with the improved crossbar technique may be an effective digital method for achieving postoperative LSB and has important clinical significance.

Correlation analysis and clinical significance of changes in upper thoracic vertebra tilt and clavicle angle pre- and post-operation

“…From these data, we found that the correlation gradually decreased as the vertebrae moved down, which may be related to compensation in the intervertebral disk. In previous research, we found a correlation between T1 changes and CA changes, took into account the flexibility between T1 and UIV, and proposed a formula to predict the ideal postoperative UIV tilt to prevent lateral shoulder imbalance after scoliosis correction surgery ( 27 ). However, in that study, we only found the phenomenon and did not conduct any further study.…”

“…In addition, our previous clinical work has already applied the research by predicting the appropriate tilt angle of the UIV through a certain formula to achieve postoperative shoulder balance as much as possible. In our previous study, we described the test method in detail, and in a prospective study, 13 scoliosis patients all achieved a satisfactory LSB ( 27 ). On the other hand, the results of the current study complement the previous data and make the previous articles seem more logical.…”