Given the complexity of revision THA, the Paprosky system identifies which acetabular supporting structures are deficient for the purposes of predicting the biologic augments and synthetic components that will be needed at the time of surgery. This classification is anatomically oriented and assesses specific osseous structures for deficiency, rather then being geared toward generalized volumetric bone loss, which is the basis of several other systems [3, 5, 12]. The Paprosky system uses preoperative radiographs to classify defects by the amount of acetabularcomponent migration and the status of the acetabular supporting structures including the anterior and posterior columns, the superior weightbearing dome, and the medialwall (Table 1). It is based primarily on ‘‘the presence or
absence of an intact acetabular rim and its ability to provide rigid support for an implanted acetabular component’’[11].