Reinforcement cages are widely used for the treatment of large acetabular defects. We report a rare case of an aseptic loosened Burch-Schneider cage causing an aneurysm of the femoral artery and life-threatening bleeding, large hematoma, and signs of hyperfibrinolysis. After performing several diagnostic procedures, the patient underwent extensive interdisciplinary revision surgery. Initial unspecific symptoms such as pain, swelling, and hematoma of the leg after acetabular reconstructions using reinforcement cages should alert clinicians to consider the possibility of vascular complications.