Relevance of pathology and basic research to the surgeon treating rotator cuff disease.

For any physician expecting a successful outcome of a treatment regimen a thorough understanding of the underlying pathogenetic mechanism and the pathology of the disease process is an absolute prerequisite. In addition, the surgeon, obviously wishing to obtain a positive outcome of the procedure, must know the reaction of the body to his or her surgical actions. In particular, he or she must be familiar with the factors guaranteeing an uneventful healing process. For example, with rotator cuff disease it is important to realize that the site of degeneration leading eventually to tearing does not lie in the tendon itself but at its insertion into bone. Moreover, the cells and vessels needed for healing after surgical repair do not originate from the torn tendinous stumps. An important source of cells and vessels is the subacromial bursa overlying the site of tearing. Consequently, the bursa must be preserved at all cost. The subchondral bone trough into which the medial tendon stump is usually anchored during repair represents the other source of healing tissue. Whereas surgeons understandably concentrate their attention on the site of tearing, the fate of the muscle in the torn bone-tendon-muscle unit must not be neglected. In experimental studies we were able to measure muscle atrophy and fat accumulation and could quantify their evolution over time. Finding no reversal of these two parameters after successful repair was disturbing. Shoulder surgeons will benefit from this comprehensive review of updated concepts.