الفهرس 
ANATOMY & BIOMECHANICSOnly 14 pages are availabe for public view
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Abstract
RTRCTs are now thought to be more common than what previously thought. It is a cause of chronic pain and considerable disability in affected subjects and are often diagnosed with difficulty even after the advents of radiological investigations and arthroscopy(1).
It has been reported that 4% of people over 40 and 50% over 60 years old have PTRCTs with or without shoulder pain(2).
The RC muscles comprise the SS, IS, TM, and SSC. They act as shoulder steerers and also act as dynamic stabilizers to the shoulder joint (3).
PTRCTs are considered a step in a sequence of changes affecting the muscles starting with inflammation and end in the form of tears that are massive and retracted .the causative factors can be classified to extrinsic and intrinsic causes. Intrinsic causes can be synonymized into the word “degeneration”. As series of vascular and metabolic changes result in degenerative tearing of the RC.
Extrinsic factors are represented mainly by subacromial impingement; with its resultant inflammation and degeneration lead to tearing in addition to other factors like GH instability, single traumatic event (e.g.: dislocation), internal impingement, and micro-trauma(4). Vascular insufficiency of the SS tendon and secondary microcirculatory disturbances have been theorized as a cause to RC tears (5).
Classic symptoms include shoulder pain, shoulder stiffness, or dysfunction on the affected side. Patients commonly report a painful arc of motion, resting pain, and nocturnal pain.
Signs and symptoms include SS weakness, weakness in external rotation and signs of SA impingement (2).