What shoulder anatomy understanding is needed to manage frozen shoulder syndrome (FSS) (adhesive capsulitis)?

Updated: Nov 12, 2020
  • Author: Jefferson R Roberts, MD; Chief Editor: S Ashfaq Hasan, MD  more...
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Answer

Critical to the understanding of frozen shoulder syndrome is the concept that shoulder function involves not only the glenohumeral joint but also scapulothoracic articulation. Clinicians must understand the essential role that the scapula plays in facilitating glenohumeral motion. Scapulothoracic and glenohumeral motion occur simultaneously following initial arm abduction. In healthy individuals, approximately one third of arm elevation in abduction is attributed to scapulothoracic motion, while two thirds is provided by glenohumeral motion.

The glenohumeral joint is enclosed by the joint capsule and is surrounded by two sleeves of muscles. The capsule normally is a loose structure with a surface area nearly twice as large as that of the humeral head. The rotator cuff tendons adjacent to the joint capsule thicken the capsule anteriorly, posteriorly, and superiorly, while the glenohumeral ligaments represent further areas of joint capsule thickening.

Histologically, the capsule consists of bundles of type I collagen. Synovial cells line the inner surface of the capsule and enclose the long head of the biceps tendon.


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