A retrospective study to reveal factors associated with postoperative shoulder imbalance in patients with adolescent idiopathic scoliosis with double thoracic curve.
OBJECTIVE Postoperative shoulder imbalance (PSI) is a critical consideration after corrective surgery for a double thoracic curve (Lenke Type 2); however, the radiographic factors related to PSI remain unclear. The purpose of this study was to identify the radiographic factors related to PSI after corrective surgery for adolescent idiopathic scoliosis (AIS) in patients with a double thoracic curve. METHODS This study included 80 patients with Lenke Type 2 AIS who underwent corrective surgery. Patients were grouped according to the presence [PSI(+)] or absence [PSI(-)] of shoulder imbalance at the final follow-up examination (differences of 20, 15, and 10 mm were used). Various radiographic parameters, including the Cobb angle of the proximal and middle thoracic curves (PTC and MTC), radiographic shoulder height (RSH), clavicle angle, T-1 tilt, trunk shift, and proximal and distal wedge angles (PWA and DWA), were assessed before and after surgery and compared between groups. RESULTS Overall, postoperative RSH decreased with time in the PSI(-) group but not in the PSI(+) group. Statistical analyses revealed that the preoperative Risser grade (p = 0.048), postoperative PWA (p = 0.028), and postoperative PTC/MTC ratio (p = 0.011) correlated with PSI. Presence of the adding-on phenomenon was also correlated with PSI, although this result was not statistically significant (p = 0.089). CONCLUSIONS Postoperative shoulder imbalance is common after corrective surgery for Lenke Type 2 AIS and correlates with a higher Risser grade, a larger postoperative PWA, and a higher postoperative PTC/MTC ratio. Presence of the distal adding-on phenomenon is associated with an increased PSI trend, although this result was not statistically significant. However, preoperative factors other than the Risser grade that affect the development of PSI were not identified by the study. Additional studies are required to reveal the risk factors for the development of PSI.
Department of Orthopaedic Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.
Choon Sung
CS
Lee
Department of Orthopaedic Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.
Chang Ju
CJ
Hwang
Department of Orthopaedic Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.
Eic Ju
EJ
Lim
Department of Orthopaedic Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.
Dong-Ho
DH
Lee
Department of Orthopaedic Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.
Jae Hwan
JH
Cho
D000293:Adolescent; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011183:Postoperative Complications / Q000000981:diagnostic imaging* / Q000209:etiology; D004856:Postural Balance; D012189:Retrospective Studies; D012600:Scoliosis / Q000000981:diagnostic imaging* / Q000601:surgery; D012782:Shoulder / Q000000981:diagnostic imaging*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery
AIS = adolescent idiopathic scoliosis; CCAD = clavicle chest cage angle difference; CSVL = central sacral vertical line; DWA = distal wedge angle; LIV = lower instrumented vertebra; MTC = middle thoracic curve; PSI = postoperative shoulder imbalance; PTC = proximal thoracic curve; PWA = proximal wedge angle; RSH = radiographic shoulder height; UIV = upper instrumented vertebra; adding-on phenomenon; adolescent idiopathic scoliosis; double thoracic curve; proximal wedge angle; shoulder imbalance; spine