2017 ISAKOS Biennial Congress ePoster #2116
Chronic Acromioclavicular Dislocation Leads to Internal Impingement
Yon-Sik Yoo, MD, PhD, Hwaseong-Si, Gyeonggi-do KOREA, REPUBLIC OF
Yong-Beom Lee, Prof., Anyang KOREA, REPUBLIC OF
Seung-Jin Lee, MD, Hwaseong-Si, Gyeonggi-do KOREA, REPUBLIC OF
Hallym University, hwasung, Gyungi-do, KOREA, REPUBLIC OF
FDA Status Not Applicable
Summary
Thus, long standing or improper treated high grade AC joint dislocation must lead to chronic rotator cuff tear according to theoretical biomechanical background
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Abstract
Introduction
The chronic high grade acromioclavicular joint dislocation must lead to internal impingement according to theoretical background. But there are no proven studies providing insight into the pathologic course of rotator cuff and labrum after loss of acromioclavicular joint integrity. The purpose of our study is to develop the patient-specific glenohumeral movement based on spatial change in scapular positions and to evaluate 3D morphological changes in rotator cuff and labrum according to this movement in patient with chronic acromioclavicular dislocation.
Methods
Using a 3D models of 15 patients with chronic acromioclavicular dislocation, glenohumeral and scapulothoracic motions were simulated. We evaluated the changes in spatial scapular position while glenohumeral abduction by measuring the degree of scapular upward rotation and posterior tilt. The contact stresses of labrum and rotator cuff were also assessed.
Results
The mean scapular upward rotation and posterior tilt angle with respect to the rib cage was 32.3±6.5° and - 7.4±8.5° on the injured side versus 44.5±7.8° and -9.7±9.5° on the uninjured side(p<0.05). The measured peak contact stress values were 7.7±6.5 MPa and 29.3±12.2 MPa for the posterosuperior labrum and the upper rotator cuff compared the value on uninjured side measured by 2.8±1.5 MPa and 8.1±7.5 MPa, respectively(p<0.05).
Discussion
Our study successfully reflected biomechanical insight into an alteration of scapula-humeral motion that may influence a rotator cuff and labral damages in chronic acromioclavicular dislocation. The finding suggested that activity requiring extreme scapular upward rotation and posterior tilt might cause rotator cuff and labral damage in biomechanical perspective.