The proximal humerus is particularly prone to pathologic fractures because of its long arm of lever, high rotational forces of the surrounding muscles and the mostly spongiform metaphyseal bone. Concludingly, besides the spine and the femur the humerus is one of the most common localizations of pathologic tumor associated fractures. The most frequently affected locations are the spine and pelvis followed by proximal parts of humerus and femur. Several primary tumors metastasize primarily in the liver and lungs but also very often in the skeletal system.
Referring to the location of these bony lesions the humerus is considered as one of the most common localization of benign bone tumors as well as of sarcomas (osteosarcoma, chondrosarcoma, Ewing’s sarcoma).
In this context the bony lesions can be divided into benign, primary malignant and secondary malignant tumorous lesions such as sarcoma and bone metastases respectively. Aggressive neoplastic or pseudo tumor-like bone lesions present the second most common reason for pathologic fractures following osteoporosis. Pathologic fractures can be caused by a variety of local and systemic disorders. In general usually pathological fractures are caused by an inadequate trauma to the bone, which is impaired by the underlying disease.