Background Previous studies reported that medial shoulder balance (MSB) with neck tilt correlated radiologically with T1 tilt, first rib angle (FRA), and cervical axis (CA), whereas lateral shoulder balance (LSB) correlated radiologically with clavicle angle (Cla-A), coracoid height difference (CHD), clavicle-rib intersection distance (CRID), and radiographic shoulder height (RSH). Nevertheless, there is a scarcity of literature correlating both the clinical and radiological shoulder balance parameters in adolescent idiopathic scoliosis (AIS) patients. This study investigates the correlations between preoperative radiological and clinical shoulder balance (MSB and LSB) in Lenke type 1 and 2 AIS patients. Methods We reviewed 50 Lenke type 1 and 2 AIS patients between 2021 and 2022. Preoperative clinical shoulder parameters included front/neck base angle, front/back clavicle angle, front/back trapezium angle ratio, front/back axilla angle, trapezial area, shoulder area index 1 (SAI 1), SAI 2, and inner/outer shoulder height (SHi/SHo). Radiological shoulder parameters included T1 tilt, FRA, CA, Cla-A, CHD, CRID, and RSH. Results Strong correlations (r ≥ 0.6) were observed between T1 tilt, FRA, and CA (MSB with neck tilt), and between Cla-A, CHD, CRID, and RSH (LSB) (r > 0.9). T1 tilt and FRA correlated strongly (r ≥ 0.6) with front and back neck base angles, Ln L/R trapezial area, SAI 1, SAI 2, and SHi, with the highest coefficients for front/back neck base angles (r ≥ 0.8). CA correlated strongly with front and back neck base angles, SAI 2, and SHi. Cla-A, CHD, CRID, and RSH correlated strongly with back clavicle angle. Conclusion MSB (T1 tilt and FRA) demonstrated very strong correlation with front and back neck base angles, and strong correlation with Ln L/R trapezial area, SAI 1, SAI 2, and SHi. Neck tilt (CA) correlated strongly with front and back neck base angles, SAI 2, and SHi. Meanwhile, LSB (Cla-A, CHD, CRID, and RSH) correlated strongly with back clavicle angle.
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