Rotator cuff tear oxidative stress induces tenocyte apoptosis causing further rotator cuff tendon degeneration. A neural theory also exists that suggests neural overstimulation leads to the recruitment of inflammatory cells and may also contribute to tendon degeneration. Tears of the rotator cuff tendon are described as partial or full thickness, and full thickness with complete detachment of the tendons from bone. Shoulder pain is variable and may not be proportional to the size of the tear. Neer promoted the concept of three stages of rotator cuff disease. Stage I, according to Neer, occurred in those younger than 25 years and involved edema and
Synovial sheath Synovial sheath A synovial sheath is one of the two membranes of a tendon sheath which covers a tendon. The other membrane is the outer fibrous tendon sheath. The tendon invaginates the synovial sheath from one side so that the tendon is suspended from the membrane by the mesotendon, through which the blood vessels reach the tendon, in places where the range of movement is extensive. The mesotendon disappears or remains in the form of narrow tendinous bands as threads known as vincula tendina. The synovial sheath is found where the tendon passes under ligaments and through osseofibrous tunnels; their