Progression to a hooked acromion could be an adaptation to an already damaged, poorly balanced rotator cuff with resultant stress on the coracoacromial arch. Other anatomical factors include an os acromiale and acromial spurs. Environmental factors include age, shoulder overuse, smoking, and medical conditions that affect circulation or impair the inflammatory and healing response, such as diabetes mellitus. Intrinsic factors
Intrinsic factors refer to injury mechanisms that occur within the rotator cuff itself. The principal is a degenerative-microtrauma model, which supposes that age-related tendon damage compounded by chronic microtrauma results in partial tendon tears that then develop into full rotator cuff tears. As a result of repetitive microtrauma in the setting of a degenerative rotator cuff tendon, inflammatory mediators alter the local environment, and 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. Surgical considerations
Depending upon the diagnosis, several treatment alternatives are available. They include revision repair, non-anatomic repair, tendon transfer and arthroplasty. When possible, surgeons make tension-free repairs in which they use grafted tissues rather than stitching to reconnect tendon segments. This can result in a complete repair. Other options are a partial repair, and reconstruction involving a bridge of biologic or synthetic substances. Partial repairs typically are performed on retracted cuff tears.Tendon transfers are prescribed for young, active cuff-tear individual who experience weakness and decreased range of motion, but little pain.
Repair can be performed through an open incision, again requiring detachment of a portion of the deltoid, while a mini-open technique approaches the tear through a deltoid-splitting approach. The latter may cause less injury to muscle and produce better results. Contemporary techniques now use an all arthroscopic approach. Recovery can take as long as three–six months, with a sling being worn for the first one–six weeks. In the case of partial thickness tears, if surgery is undertaken, tear completion (converting the partial tear to a full tear) and then repair, is associated with better early outcomes than transtendinous repairs (where the intact fibres are preserved) and no difference in failure rates.Biceps tenotomy and tenodesis are often performed concomitantly with rotator cuff repair or as separate procedures, and can also cause shoulder pain. Tenodesis, which may be performed as an arthroscopic or open procedure, generally restores pain free motion it the biceps tendon, or attached portion of the labrum, but can cause pain. Tenotomy is a shorter surgery requiring less rehabilitation, that is more often performed in older patients, though after surgery there can be a cosmetic popeye sign visible in thin arms.In a small minority of cases where extensive arthritis has developed, an option is shoulder joint replacement (arthroplasty). Specifically, this is a reverse shoulder replacement, a more constrained form of shoulder arthroplasty that allows the shoulder to function well even in the presence of large full thickness rotator cuff tears.