A rare avascolar osteonecrosis of the knee related to biphosphonate treatment in a patient with metastatic breast cancer.

Bisphosphonates are widely used both in the multidisciplinary management of bone metastases, especially osteolytic lesions from solid tumors or multiple myeloma, and of osteoporosis.Aseptic osteonecrosis, especially of the jaw, is among the well-known, although uncommon, side effects of bisphosphonates. Osteonecrosis of other bones has been very rarely reported with the use of bisphosphonates.We describe a rare case of osteonecrosis of the distal femur associated with the use of bisphosphonates in a 74 years old female patient with metastatic breast cancer.