Malignancy
What is it? Malignancies can sometime present as a non-traumatic knee effusion. They can include, but are not limited to, bony or cartilaginous tumors and cancers.
How does it present? Often present as an effusion and knee pain, usually non-traumatic. However, patients may often associate their knee pain with some presumed traumatic event in the past. Nighttime pain may be a complaint.
Common exam findings: Effusion may be seen in cases of malignancy, but findings may otherwise be nonspecific.
Tests and treatment: Knee x-rays should be done, and if further testing is indicated, a computer tomography (CT scan) or magnetic resonance imaging (MRI) can be done to further evaluate for bony or soft tissue malignancies. Treatment depends on the type of malignancy and should be referred to an orthopedic surgeon and oncologist.