• Danil Rybalko, Aimee Bobko, Farid Amirouche, Dmitriy Peresada, Awais Hussain, Michael Patetta, Anshum Sood, Jason Koh, and Benjamin Goldberg.
• Department of Orthopaedic Surgery, University of Illinois at Chicago, Chicago, IL, USA.
• J Shoulder Elbow Surg. 2020 Oct 1; 29 (10): 1959-1966.

BackgroundSuperior capsular reconstruction (SCR) has been gaining popularity as a treatment for irreparable rotator cuff tears (RCTs), especially in younger patients. This biomechanical study aimed to investigate how SCR affects functional abduction force, humeral head migration, and passive range of motion following an irreparable RCT. We hypothesized that SCR will restore these parameters to nearly intact shoulder levels.MethodsSix fresh-frozen cadaveric shoulders were evaluated using a custom biomechanical testing apparatus. Each shoulder was taken through 3 conditions: (1) intact (control); (2) irreparable, complete supraspinatus (SS) tear; and (3) SCR. Functional abduction force, superior humeral head migration, and passive range of motion, including axial shoulder rotation, were measured in static condition at 0°, 30°, and 60° of glenohumeral abduction. Data were analyzed using the paired Student t test or Wilcoxon signed rank test, depending on the results of normality testing.ResultsThe irreparable SS tear resulted in significantly lower functional abduction force at 30° of abduction (P = .01) and a trend toward a decrease (P = .17) at 60° compared with the intact configuration. SCR shoulders produced greater functional force at 0° compared with the tear configuration (P = .046). Humeral head migration was significantly increased by 4.4 and 3.0 mm at 0° and 30° of abduction, respectively, when comparing the intact vs. SS tear configurations (P = .001). SCR decreased superior migration down to levels of intact shoulders at 0° and 30° of abduction (P = .008 and P = .013, respectively) and was not significantly different from the intact configuration at any angle. SCR decreased passive shoulder extension compared with the tear configuration and increased abduction compared with the intact configuration (P = .007 and P = .03, respectively). The overall arc of axial rotation was not significantly different between SCR and the intact configuration at any angle.ConclusionsIn the setting of an irreparable SS tear, SCR restores key biomechanical parameters of the shoulder to intact levels. SCR should be considered for qualifying patients with irreparable RCTs.Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.

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