Periprosthetic osteolysis after total joint replacement is a well described complication. This normal slowly increasing process is caused by infection, implant loosening or more special, debris induced. However malignant processes may rarely occur at exact this location too. Based on clinical presentation and imaging it is sometimes difficult to exclude a local malignant process. We report two cases of extensive osteolysis after total hip replacement, including their follow up and a review of the relevant literature.

Two female patients developed massive osteolysis in periprosthetic areas (pelvic area and proximal femur as well as distal femur) after being treated by total hip arthroplasty 14 and 18 years ago. In both cases a tumorous process was suspected after imaging and they were therefore referred to our clinic. In one case a rapidly progressing soft tissue swelling with extensive peri-articular osteolysis was considered to be a malignant tumour. After an incisional biopsy, an embolisation had to be performed due to continuous massive bleeding. Histology revealed a superinfected polyethylene disease, treated with a two stage revision surgery. The second patient presented with an impending fracture due an unusual osteolysis at the tip of the stem. Here again polyethylene debris was found at biopsy.

Extensive osteolysis and/or soft tissue swelling caused by polyethylene debris may sometimes be difficult to differ from a tumorous process. As a guideline presented by Min WK. et al in 2008 a reactive bone-destroying process normally proceeds slowly in contrast to a more rapid progression in malignant disease. However, as presented in the first of our cases, exemptions may occur. In these cases a biopsy or at least a frozen section at operation should be obtained in order to exclude a real neoplasm.