| Objective: to investigate the effect of correction rate of upper thoracic curvature(PTC)and main thoracic curvature(MTC)on postoperative shoulder balance in patients with Lenke 1 adolescent idiopathic scoliosis(AIS).Methods:the data of 50 patients with AIS who underwent posterior spinal deformity correction surgery in the Department of Spinal surgery of the first affiliated Hospital of Xinjiang Medical University from January 2013 to January 2020 and followed up for more than 6 months were retrospectively analyzed.There were 12 males and 38 females with a median age of 15(14-16)years(range,13-18 years).The patients were divided into two groups according to different shoulder imbalance criteria.The imaging parameters such as MTC Cobb angle,PTC Cobb angle,clavicle angle(CA),first rib inclination angle(FRA)and PTC flexibility,MTC flexibility,PTC correction rate,and MTC correction rate were evaluated before the operation,after the operation,and at the last follow-up.The factors related to postoperative shoulder balance and the last shoulder balance were analyzed.Multivariate logistic regression analysis was used to determine the independent risk factors of postoperative shoulder imbalance and last shoulder imbalance.Results: the average follow-up time was 18(11 ～ 24)months(range,6～ 84 months).Among the three groups with different shoulder balance criteria,it was found that the PTC correction rate in the shoulder imbalance group was significantly lower than that in the shoulder balance group(P>0.05).Under the standard of shoulder imbalance with CA absolute value >2 °and 2.5 °,there was a significant difference in postoperative MTC correction rate,and the postoperative MTC correction rate in the shoulder balance group was higher than that in the shoulder imbalance group.No matter what kind of shoulder balance standard,it was found that the postoperative PTC correction rate,MTC correction rate,and the ratio of MTC to PTC correction rate were all related to the lateral shoulder balance after the operation.Only in the group with CA absolute value >3 °,no correlation was found between postoperative MTC correction rate and postoperative shoulder balance.The correlation between PTC correction rate and lateral shoulder balance was more significant in the three groups.Logistic regression analysis showed that postoperative PTC correction rate was an independent risk factor for postoperative lateral shoulder balance.The postoperative shoulder and shoulder imbalance was analyzed by chi-square automatic interactive detection.When the ratio of MTC correction rate to PTC correction rate was more than 1.5,no matter which standard group,there would be patients with lateral shoulder imbalance.However,during the last follow-up,no correlation was found between the correction rate and the lateral shoulder balance during the last follow-up.Binary logistic regression analysis showed that preoperative CA was a risk factor for the last shoulder imbalance.In addition,no matter after the operation or at the last follow-up,the FRA was only correlated with the postoperative PTC Cobb angle(P> 0.05).Conclusion: In patients with Lenke 1 AIS,the lateral shoulder balance is only related to the PTC Cobb angle either after the operation or at the last follow-up.The correction rate of PTC,the correction rate of MTC,and their ratio were correlated with the balance of the lateral shoulder and shoulder after the operation.The matching of PTC and MTC correction can ensure the balance of the lateral shoulder after the operation.The amount of correction of postoperative PTC may be the protective factor of the lateral shoulder balance after the operation.However,for long-term shoulder balance,the effect of PTC and MTC correction rate is not as significant as after the operation.Compensatory factors such as the aggravation of PTC,torso tilt,and lumbar bending will have an impact on the last lateral shoulder balance.The recovery of the lateral shoulder balance still needs further study. |
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