Abstract
Total knee replacement with mega prosthesis for periprosthetic fractures after total knee arthroplasty is related to early functional recovery, but aseptic loosening of the implant has been a major reoperation factor in the long-term outcome of total knee replacement with mega prosthesis. Extracortical bone formation caused by bone-collar interface osteointegration may decrease the probability of aseptic loosening by promoting bone formation and improving bone-implant fixation. Here, we report a case of total knee replacement using mega prosthesis with porous-coated collar showing extra bone growth without osteointegration of prosthesis and leading to aseptic loosening.