Biomechanical Effects of Acromioplasty on Superior Capsule Reconstruction for Irreparable Supraspinatus Tendon Tears

• Published in: The American journal of sports medicine 2016-01, Vol.44 (1), p.191-197
• Main Authors: Mihata, Teruhisa, McGarry, Michelle H., Kahn, Timothy, Goldberg, Iliya, Neo, Masashi, Lee, Thay Q.
• Format: Article
• Language: English
• Subjects: Acromion - physiology; Acromion - surgery; Aged; Aged, 80 and over; Arthroplasty - methods; Biomechanical Phenomena; Cadaver; Case-Control Studies; Fascia Lata - physiology; Female; Humans; Humeral Head - injuries; Hypotheses; Joint Instability - physiopathology; Joint Instability - surgery; Knee; Lacerations - surgery; Ligaments, Articular - physiology; Ligaments, Articular - surgery; Male; Middle Aged; Pressure; Range of Motion, Articular - physiology; Rotator Cuff - physiology; Rotator Cuff Injuries; Rupture - physiopathology; Rupture - surgery; Scapula - physiology; Scapula - surgery; Shoulder; Shoulder Impingement Syndrome - physiopathology; Shoulder Impingement Syndrome - surgery; Shoulder Joint - surgery; Sports medicine; Tendon Injuries - surgery; Tendons - physiology; Tendons - surgery; Transplants
• ISSN: 0363-5465; 1552-3365
• DOI: 10.1177/0363546515608652

Background: Acromioplasty is increasingly being performed for both reparable and irreparable rotator cuff tears. However, acromioplasty may destroy the coracoacromial arch, including the coracoacromial ligament, consequently causing a deterioration in superior stability even after superior capsule reconstruction. Purpose/Hypothesis: The purpose of this study was to investigate the effects of acromioplasty on shoulder biomechanics after superior capsule reconstruction for irreparable supraspinatus tendon tears. The hypothesis was that acromioplasty with superior capsule reconstruction would decrease the area of subacromial impingement without increasing superior translation and subacromial contact pressure. Study Design: Controlled laboratory study. Methods: Seven fresh-frozen cadaveric shoulders were evaluated using a custom shoulder testing system. Glenohumeral superior translation, the location of the humeral head relative to the glenoid, and subacromial contact pressure and area were compared among 4 conditions: (1) intact shoulder, (2) irreparable supraspinatus tendon tear, (3) superior capsule reconstruction without acromioplasty, and (4) superior capsule reconstruction with acromioplasty. Superior capsule reconstruction was performed using the fascia lata. Results: Compared with the intact shoulder, the creation of an irreparable supraspinatus tear significantly shifted the humeral head superiorly in the balanced muscle loading condition (without superior force applied) (0° of abduction: 2.8-mm superior shift [P = .0005]; 30° of abduction: 1.9-mm superior shift [P = .003]) and increased both superior translation (0° of abduction: 239% of intact [P = .04]; 30° of abduction: 199% of intact [P = .02]) and subacromial peak contact pressure (0° of abduction: 308% of intact [P = .0002]; 30° of abduction: 252% of intact [P = .001]) by applying superior force. Superior capsule reconstruction without acromioplasty significantly decreased superior translation (0° of abduction: 86% of intact [P = .02]; 30° of abduction: 75% of intact [P = .002]) and subacromial peak contact pressure (0° of abduction: 47% of intact [P = .0002]; 30° of abduction: 83% of intact [P = .0005]; 60° of abduction: 38% of intact [P = .04]) compared with after the creation of a supraspinatus tear. Adding acromioplasty significantly decreased the subacromial contact area compared with superior capsule reconstruction without acromioplasty (0° of abduction: 26% decrease [P = .01]; 30° of abd