2. Pathogenesis

Disorders of the LHBBT are often classified as primary or secondary. Primary lesions are isolated to the LHBBT, with no associated abnormalities elsewhere in the shoulder. Secondary lesions occur in conjunction with pathological changes in the adjacent osseous, tendinous, ligamentous, or muscular structures. It has been estimated that secondary lesions represent more than 95% of the LHBBT disorders, and two common sites for associated abnormalities are the glenohumeral joint and rotator cuff tendons.19