Architectural gear ratio and their accompanying tendons. These muscles form a cuff around the glenohumeral joint and function to stabilize and manipulate the shoulder. The pennation angle of the rotator cuff myofibers, the angle at which fibers connect to the associated tendon, affects the contractile properties and function of the whole pennate muscle. For example, the pennation angle determines the architectural gear ratio at which a pennate muscle operates. A large initial pennation angle results in a large AGR and velocity amplification. A 2011 study on human cadaveric shoulders suggests tendon tears may affect the pennation angle of the rotator cuff muscles. Researchers
Rotator cuff tear is usually required to reattach the tendon to the bone. If a significant bone spur is present, any of the approaches may include an acromioplasty, a subacromial decompression, as part of the procedure. Subacromial decompression, removal of a small portion of the acromion that overlies the rotator cuff, aims to relieve pressure on the rotator cuff in certain conditions and promote healing and recovery. Although subacromial decompression may be beneficial in the management of partial and full-thickness tear repair, it does not repair the tear itself and arthroscopic decompression has more recently been combined with "mini-open" repair of the rotator