It is important that the summary of a selective literature search for the third most common musculoskeletal complaint in orthopedic practice is published in Deutsches Ärzteblatt (1). What is surprising and sobering is the fact that the focus of the article is on well-known structural findings and surgical options, whereas the orthopedic aspect of structural functional causes is barely mentioned and is given too short shrift. The learning objectives are therefore not met.
How to explain the development of structural adjustments and defects in this “epidemic”? The human shoulder develops primarily as a pull-rotation system, in contrast to the hip, which is a push-rotation system (2). At the start of a shoulder movement, the humeral head in the glenoid needs to be pulled downwards and centered by using the humeral distractors (the long head of the biceps tendon and the latissimus dorsi muscle), before abduction of the glenohumeral joint becomes possible without pathological humero-acromial impingement and squeezing of the rotator cuff, which in the long term leads to subacromial adjustments and destructions. The element that is being moved is primarily the humeral head and not the acromion. Modern lifestyles and/or unilateral or incorrect training will weaken the humeral distractors vis-à-vis the cranializing and ventralizing muscle groups, and the physiologically necessary sequence of pull-rotation in the glenoid will be disrupted (3). Congenital or acquired instabilities also play a part. Expert sonography allows for functional analysis of the movement and stability of the shoulder long before structural remodeling processes will be visible on magnetic resonance imaging or changes are seen on the conventional radiograph (4).
Early, timely, and systematic instruction on optimizing movement patterns and behavioral habits can help prevent the development of the described structural defects (4, 2).
References
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