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 postoperative pain or pain medication use apparently are not seen between arthroscopic- and open-surgery. Even for full-thickness rotator cuff tears, conservative care (i.e., nonsurgical treatment) outcomes are usually reasonably good. However, many people still have disability and pain despite nonsurgical therapies. For massive tears of the rotator cuff, surgery has shown durable outcomes on 10-year follow-up. However, the same study demonstrated ongoing and progressive fatty atrophy and repeat tears of the rotator cuff. MRI evidence of fatty atrophy in the rotator cuff prior to surgery is predicative of a poor surgical outcome. If the rotator cuff is completely torn, surgery