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How Common Is Medial and Lateral Shoulder Discordance in Lenke 1 and 2 Curves?

A Preoperative Analysis of Medial and Lateral Shoulder Balance Among 151 Lenke 1 and 2 Adolescent Idiopathic Scoliosis Patients

Chung, Weng Hong, MD, MSOrth; Chiu, Chee Kidd, MBBS, MSOrth; Ng, Sherwin Johan, MBBS; Goh, Saw Huan, MBBS; Chan, Chris Yin Wei, MD, MSOrth; Kwan, Mun Keong, MBBS, MSOrth

doi: 10.1097/BRS.0000000000002890

Study Design. Retrospective study of prospectively collected data.

Objective. To analyze the incidence and the patterns of medial and lateral shoulder discordance among Lenke 1 and 2 patients.

Summary of Background Data. Postoperative shoulder imbalance (PSI) is still common in Lenke 1 and 2 adolescent idiopathic scoliosis (AIS). This could be due to presence of medial dan lateral shoulder discordance.

Methods. One hundred fifty-one Lenke 1 and 2 AIS patients were recruited. Lenke 1 curves were subclassified into Lenke 1-ve (flexible) (proximal thoracic side bending [PTSB] Cobb angle <15°) and 1+ve curves (stiff) (PTSB Cobb angle between 15° and 24.9°). T1 tilt represented “medial shoulder balance” and radiological shoulder height (RSH) represented “lateral shoulder balance.” We categorized patients into three concordant shoulder pattern types (medial balanced/lateral balanced [MBLB], medial imbalanced+ve/lateral imbalanced+ve (MI+ve/LI+ve), medial imbalanced–ve/lateral Imbalanced–ve (MI–ve/LI–ve), and six discordant shoulder pattern types.

Results. The mean age was 16.2 ± 5.7 years. Eighty-one patients (53.6%) had concordant pattern and 70 patients (46.4%) had discordant pattern. Lateral shoulder imbalance was noted in 35.1% of patients and medial shoulder imbalance in 43.7% of patients. In Lenke 1–ve curves, 35 patients (68.6%) had concordant shoulder imbalance with medial imbalanced–ve/lateral imbalanced–ve (MI–ve/LI–ve) being the commonest pattern (68.6%). In Lenke 1+ve curves, 33 patients (55.0%) had concordant shoulder pattern with medial balanced/lateral balanced (MB/LB) being the commonest type (57.6%). In Lenke 2 AIS, 27 patients (67.5%) had discordant pattern with medial imbalanced+ve/lateral balanced (MI+ve/LB) being the commonest pattern (44.4%) (P value = 0.002).

Conclusion. 46.4% Lenke 1 and 2 AIS patients had shoulder discordant pattern. This was more prevalent in Lenke 2 curves (67.5%). In Lenke 1-ve (flexible) curves, MI–ve/LI–ve pattern was the commonest pattern. In Lenke 1+ve curves (stiff), there were almost equal number of concordant and discordant shoulder pattern. In Lenke 2 patients, the most common pattern was MI+ve/LB.

Level of Evidence: 4

Shoulder discordance was prevalent in 46.4% Lenke 1 and 2 patients. Most of the Lenke 1 −ve curves were concordant (68.6%). In Lenke 1 +ve, the prevalence of concordant (55.0%) and discordant (45.0%) shoulder pattern was almost equal. In Lenke 2, discordant shoulder imbalance was more common (67.5%).

Department of Orthopaedic Surgery, National Orthopaedic Centre of Excellence for Research and Learning (NOCERAL), Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.

Address correspondence and reprint requests to Chris Yin Wei Chan, MD, MSOrth, Department of Orthopaedic Surgery, National Orthopaedic Centre of Excellence for Research and Learning (NOCERAL), Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; E-mail:

Received 6 June, 2018

Revised 16 August, 2018

Accepted 10 September, 2018

The manuscript submitted does not contain information about medical device (s)/drug (s).

No funds were received in support of this work.

No relevant financial activities outside the submitted work.

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