Predictors of shoulder level after spinal fusion in adolescent idiopathic scoliosis
For patients with adolescent idiopathic scoliosis, shoulder balance influences their treatment satisfaction and psychological well-being. Several parameters are known to affect postoperative shoulder balance, but few prognostic models are as yet available.
This study aimed to identify independent predictive factors that can be used to assess preoperatively which patients are at risk of postoperative shoulder elevation, and to build a linear prediction model.
N = 102 patients with all Lenke types were reviewed radiographically before surgery and 1 year afterward. The outcome measures were coracoid height difference (CHD), clavicular angle (CA), and clavicle–first rib intersection difference (CiRID). Predictive factors commonly used in the literature were investigated using correlation analysis and statistical testing. Significant contributing factors were included in three multiple linear regression models (for CHD, CA, and CiRID).
The mean shoulder level (CHD) significantly changed from a lower left shoulder value of −8.5 mm before surgery to 3.3 mm at the follow-up examination. A high preoperative left shoulder level by CiRID, a large amount of Cobb angle correction of the distal thoracic curve, a low preoperative Cobb angle in the lumbar curve, and a structural proximal thoracic curve proved to be determinants and thus risk factors for left-sided shoulder elevation after surgery. The three models predicting CHD, CA, and CiRID at the follow-up examination included these four risk factors and were significant.
Preoperative variables have the strongest influence on shoulder level after spinal instrumentation. Additionally, extensive correction of the distal thoracic curve can cause elevation of the left shoulder.
KeywordsAdolescent idiopathic scoliosis Shoulder balance Prediction model Corrective surgery
Compliance with ethical standards
Conflict of interest
None of the authors has any potential conflict of interest.
- 6.Sanders JO, Polly DW Jr, Cats-Baril W, Jones J, Lenke LG, O’Brien MF, Stephens Richards B, Sucato DJ, AIS Section of the Spinal Deformity Study Group (2003) Analysis of patient and parent assessment of deformity in idiopathic scoliosis using the Walter Reed Visual Assessment Scale. Spine (Phila Pa 1976) 28(18):2158–2163. doi: 10.1097/01.BRS.0000084629.97042.0B CrossRefGoogle Scholar
- 8.Kuklo TR, Lenke LG, Graham EJ, Won DS, Sweet FA, Blanke KM, Bridwell KH (2002) Correlation of radiographic, clinical, and patient assessment of shoulder balance following fusion versus nonfusion of the proximal thoracic curve in adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 27(18):2013–2020CrossRefGoogle Scholar
- 11.Cao K, Watanabe K, Hosogane N, Toyama Y, Yonezawa I, Machida M, Yagi M, Kaneko S, Kawakami N, Tsuji T, Matsumoto M (2014) Association of postoperative shoulder balance with adding-on in Lenke Type II adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 39(12):E705–E712. doi: 10.1097/BRS.0000000000000325 CrossRefGoogle Scholar
- 15.Yagi M, Takemitsu M, Machida M (2013) Chest cage angle difference and rotation of main thoracic curve are independent risk factors of postoperative shoulder imbalance in surgically treated patients with adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 38(19):E1209–E1215. doi: 10.1097/BRS.0b013e31829e0309 CrossRefGoogle Scholar
- 16.Suk SI, Kim WJ, Lee CS, Lee SM, Kim JH, Chung ER, Lee JH (2000) Indications of proximal thoracic curve fusion in thoracic adolescent idiopathic scoliosis: recognition and treatment of double thoracic curve pattern in adolescent idiopathic scoliosis treated with segmental instrumentation. Spine (Phila Pa 1976) 25(18):2342–2349CrossRefGoogle Scholar
- 20.Lee CS, Chung SS, Shin SK, Park YS, Park SJ, Kang KC (2011) Changes of upper thoracic curve and shoulder balance in thoracic adolescent idiopathic scoliosis treated by anterior selective thoracic fusion using VATS. J Spinal Disord Tech 24(7):462–468. doi: 10.1097/BSD.0b013e318204d553 CrossRefPubMedGoogle Scholar
- 24.Newton PO, O’Brien MF, Shufflebarger HL, Betz RR, Dickson RA, Harms J (2010) Idiopathic scoliosis. The harms study group treatment guide. Thieme, New YorkGoogle Scholar
- 30.Ilharreborde B, Even J, Lefevre Y, Fitoussi F, Presedo A, Souchet P, Pennecot GF, Mazda K (2008) How to determine the upper level of instrumentation in Lenke types 1 and 2 adolescent idiopathic scoliosis: a prospective study of 132 patients. J Pediatr Orthop 28(7):733–739. doi: 10.1097/BPO.0b013e318185a36b CrossRefPubMedGoogle Scholar
- 34.Matsumoto M, Watanabe K, Kawakami N, Tsuji T, Uno K, Suzuki T, Ito M, Yanagida H, Minami S, Akazawa T (2014) Postoperative shoulder imbalance in Lenke Type 1A adolescent idiopathic scoliosis and related factors. BMC Musculoskelet Disord. doi: 10.1186/1471-2474-15-366 PubMedPubMedCentralGoogle Scholar
- 38.Yang S, Feuchtbaum E, Werner BC, Cho W, Reddi V, Arlet V (2012) Does anterior shoulder balance in adolescent idiopathic scoliosis correlate with posterior shoulder balance clinically and radiographically? Eur Spine J 21(10):1978–1983. doi: 10.1007/s00586-012-2434-5 CrossRefPubMedPubMedCentralGoogle Scholar