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Risk Factors for Postoperative Shoulder Imbalance in Patients With Lenke Type 1 and 2 Scoliosis Treated Using the
Arihisa Shimura1, Hidetoshi Nojiri1, Muneaki Ishijima1
1Department of Orthopaedics, Juntendo University Faculty of Medicine, Tokyo, Japan.
Study Design:
This was a multicenter retrospective cohort study.
Objective:
We investigated the incidence of postoperative shoulder imbalance (PSI) and its risk factors in patients with Lenke types 1 and 2 scoliosis corrected using vertebral coplanar alignment (VCA).
Summary Of Background Data:
PSI in scoliosis affects patient quality of life. While other correction methods have reported a high correction rate for the main thoracic curve (MTC) in relation to PSI, this correlation has not been confirmed for the VCA technique.
Materials And Methods:
We studied 176 patients with Lenke types 1 and 2 scoliosis who underwent posterior corrective fusion surgery using the VCA technique at 11 institutions. At 2 years postoperatively, patients were divided into two groups based on radiographic shoulder height (RSH): PSI- (RSH<2 cm) and PSI+ (RSH ≥2 cm) groups. We analyzed the risk factors for PSI.
Results:
The overall incidence of PSI 2 years postoperatively was 11.4% (20/176), with 9.2% (11/119) and 15.8% (9/57) in patients with Lenke types 1 and 2, respectively. Contrary to a previous study, a high MTC correction rate did not emerge as a risk factor for PSI. Instead, preoperative left shoulder elevation, low postoperative thoracic kyphosis, greater T1 tilt, and high apical vertebral body-to-rib ratio were associated with PSI in patients with Lenke type 1. Preoperative left shoulder elevation and a low postoperative proximal thoracic curve (PTC) correction rate were identified as risk factors for PSI in patients with Lenke type 2.
Conclusion:
Our results suggest that proper PTC correction, rather than compromising MTC correction, may help prevent PSI in the VCA technique. This method is particularly advantageous for addressing Lenke type 1 scoliosis and yields favorable outcomes in shoulder balance. Patients with preoperative left shoulder elevation, especially Lenke type 2, are at high risk of developing PSI.
Level Of Evidence:
Level 4.
