Effect of Scapular Orientation on Shoulder Internal Impingement in a Cadaveric Model of the Cocking Phase of Throwing

• DOI: 10.2106/jbjs.j.01972
• Publication Date: 2012-11-15T20:56:59Z
• Authors: Teruhisa Mihata; Bong Jae Jun; Christopher N.H. Bui; James Hwang; Michelle H. McGarry; Mitsuo Kinoshita; Thay Q. Lee
• Keywords: Internal Rotation; Cadaveric spasm

Background: Although deviations in scapular orientation are thought to predispose shoulder injuries throwing athletes, the biomechanical mechanism underlying athletes with an altered remains unclear. Methods: Seven fresh-frozen cadaveric shoulders were evaluated at 90° of abduction, humerus externally rotated from maximum angle, simulate late cocking phase motion. Loads applied deltoid, pectoralis major, latissimus dorsi, teres and all rotator cuff muscles. Contact pressure glenohumeral joint was measured use a sensor. The area internal impingement calculated on basis three-dimensional position data. Glenohumeral contact compared between 20°, 30°, 40° rotation; upward 0° 10° anterior tilt. Data analyzed repeated-measures analysis variance Tukey post hoc test. Results: its posterior aspect joint. increased increasing rotation. rotation significantly (43.4%) greater than that 20° (p < 0.01), (43.1%) 0.05). Decreasing resulted increase area. motion 38.1% less 0.001) 28.9% 30° 0.01). Conclusions: Increasing decreasing tendon tuberosity glenoid during simulated Clinical Relevance: Shoulder is accentuated by or scapula