• Kai Cao, Kota Watanabe, Naobumi Hosogane, Yoshiaki Toyama, Ikuho Yonezawa, Masafumi Machida, Mitsuru Yagi, Shinjiro Kaneko, Noriaki Kawakami, Taichi Tsuji, and Morio Matsumoto.
• *Department of Orthopaedic Surgery, Keio University, Tokyo, Japan †Department of Orthopaedic Surgery, the First Affiliated Hospital of Nanchang University, Nanchang, China ‡Department of Orthopaedic Surgery, Juntendo University School of Medicine, Tokyo, Japan §Department of Orthopaedic Surgery, National Hospital Organization Murayama Medical Center, Tokyo Japan; and ¶Department of Orthopaedic Surgery, Meijo Hospital, Nagoya, Japan.
• Spine. 2014 May 20;39(12):E705-12.

Study DesignA retrospective, multicenter study.ObjectiveTo investigate the relationship between postoperative shoulder balance and adding-on in Lenke type 2 adolescent idiopathic scoliosis.Summary Of Background DataPostoperative shoulder imbalance (PSI) and adding-on are the main postoperative complications occurring at the proximal to upper instrumented vertebra and the distal to the lower instrumental vertebra (LIV), respectively. Inadequate selection of LIV in the selective thoracic fusion surgery may result in postoperative distal adding-on. It remains unclear whether postoperative shoulder balance is associated with postoperative adding-on.MethodsPreoperative, postoperative, and 2-year follow-up radiographs of 142 consecutive patients with Lenke type 2 curves who underwent posterior-fusion surgery were analyzed. The patients were grouped into PSI positive and negative at follow-up. Radiographical and categorical factors between patients with and without PSI were compared. The relationship between the radiographical shoulder height and the parameters of adding-on were analyzed.ResultsPSI occurred in 23 patients (16.2%) and distal adding-on was recognized in 20 patients (14.1%) at final follow-up. The occurrence of adding-on was significantly lower in the shoulder imbalance group at follow-up (P < 0.01). There was no shoulder imbalance occurring in the patients with distal adding-on at final follow-up (P < 0.01). Correlation analysis showed that the radiographical shoulder height was positively correlated with the change in the angulation of the first disc below LIV (r = 0.228, P ≤ 0.01) and negatively correlated with the deviation change of the LIV+1 at follow-up (r = -0.254, P ≤ 0.01).ConclusionThe postoperative shoulder balance and postoperative distal adding-on were weakly but significantly associated with each other, and both shoulder imbalance and adding-on need to be prevented in Lenke type 2 curves.

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