[Tibial diaphysis fractures below a total knee prosthesis].

The fractures of the tibial diaphysis below a total knee prosthesis are a surgical challenge and intra medullary nailing seems impossible. For the SOFCOT 2005 symposium on peri prosthetic fractures we reviewed our files: six cases were found and analysed. These fractures are rare: 5 cases from the symposium (out of 96 periprosthetic fractures at the knee) are reported plus a more recent one. They were observed in elderly (over 70) women except two cases of rheumatoid arthritis. All the patients were osteoporotic either due to aging or to a long duration corticosteroid treatment. All happened after minor trauma (fall from height). The fractures were classified as SOFCOT C1: letter C means diaphyseal below the prosthetic keel or stem, number 1 means: a well-fixed implant. Intra medullary nailing became the preferred treatment over time. A good analysis of the preoperative lateral radiograph of the knee shows if there is room enough for the nail between the prosthetic keel and the anterior tibial tuberosity, the nail remaining outside the synovium. Bone healed as usually for this type of fracture without impairment of knee or ankle function. However the patients became more dependent. In some instances, an unusual type of fracture may need an unusual treatment.