Objectives: Today, the decision to operate on a patient with extensive osteolysis is based on the likelihood that a well-fixed cup may become loose after a certain undetermined period. In a radiographically stable cup, excessive osteolysis can occur as a result of wear. When preoperative evaluation determines that the component is not loose but can become unstable as a result of ongoing osteolytic process around it, then the conventional surgical approach is to evaluate the condition of the metal shell intraoperatively and to try debridement of accessible pelvic osteolytic lesions followed by grafting with particulate graft material. Surgical access to these lesions is always difficult, and surgical removal and grafting of the lesion is also unsatisfactory. When osteolytic lesions lead to segmental defects and/or involve the posterior and/or anterior column, removal of bone ingrown shells causes additional substantial bone loss. CT can be used as a screening tool and could differentiate between progressive osteolysis and retroacetabular stress shielding that simply reflects stable osseous integration of the acetabular press-fit fixation [1, 4]. A computer-assisted surgical approach for patients with CT-detected osteolytic lesions would enable the surgeon to treat these progressive osteolytic lesions early before loosening occurs or the cup becomes unstable, thereby eliminating the need for revision surgery (cup removal) and its associated risks.