Knee pain in patients with cancer after chemotherapy, radiotherapy, and bone marrow transplantation.

The causes of knee pain in patients with cancer with are different from those without cancer, and the purpose of this study was to evaluate these differences. Thirty-six patients with cancer who had knee pain who had undergone 1 or more modalities of treatment, including chemotherapy, radiotherapy, and bone marrow transplant, for a primary diagnosis of cancer were compared with a cohort of 40 patients without cancer who had knee pain. All patients were evaluated clinically and underwent radiographic examination, and some underwent computed tomography or magnetic resonance imaging examination. Among patients with a primary diagnosis of cancer, the most common diagnosis was lymphoma (n=10), and the most common causes of knee pain were avascular necrosis of bone, osteoarthritis, insufficiency fractures, and septic arthritis. In 5 patients, the classical signs of a septic knee were not present. Other causes of knee pain included meniscus tear and anterior cruciate ligament rupture with instability. The most common diagnosis in patients without cancer was osteoarthritis of the knee. No patient without cancer was diagnosed with avascular necrosis, metastatic lesion, or insufficiency fracture. Two patients without cancer were diagnosed with septic arthritis of the knee. This study showed that the causes of knee pain in patients with cancer are different from those without cancer. Septic arthritis may present without the classical clinical signs in patients with cancer, and a high index of suspicion should be maintained for it.