This classification system was developed based on clinically significant recurrent patterns of acetabular bone loss. The classification has now been refined with four specific radiographic parameters that provide specific criteria to classify each defect accurately. This detailed radiographic analysis is based on findings on the plain anterior-posterior pelvis radiograph and eliminates the need for costly computed tomography scans. Each defect classification type also has a clinically proven reconstruction method available. The failed acetabulum can be assessed accurately and easily with this method.