Serious consequences of the wrong diagnosis of meniscal lesion in a case of stress fracture of the distal femur.

We report on a 42-year-old runner who developed pain on weight bearing during his training in his right femur that radiated to the knee. A pulled muscle was suspected and treatment with nonsteroidal anti-inflammatory drugs initiated. Because of persisting pain, radiological diagnosis was started and a lesion of the meniscus suspected. The radiograph of the knee was negative and magnetic resonance imaging (MRI) showed a mild degeneration of the meniscus. Six weeks after the symptoms started, the patient underwent arthroscopy based on the MRI findings. Intraoperatively, while his leg was being fixed in the leg-holder, a supracondylar fracture of the left femur occurred. A pathologic fracture was suspected and the patient was admitted to our hospital. Another MRI and a biopsy examination were performed. Histopathologic findings were normal concerning malignancy, and osteosynthesis was performed. The subsequent analysis of the first MRI showed intramedullary and periosteal edema with high signal intensity, which led to the suspicion of a pre-existing stress fracture. After 6 months, the patient returned to sports. Because of insufficient initial anamnesis and clinical examination, a diagnostic algorithm of the stress fracture had not been kept. Additionally, in these cases, biopsy must be performed to obtain a reliable diagnosis. This mistake led to a fracture of the femur and a long rehabilitation for this patient.