ABSTRACT
A 24-year-old man underwent percutaneous fixation with pins for an undisplaced patellar fracture. At 7 months follow-up postoperatively, he presented with recurrent, painful swelling of the operated knee following trivial activities of daily life. Aspiration had been performed two times before he presented to us with symptoms. An x-ray showed that one of the pins was suspected to be protruding at the inferior pole of the patella. Magnetic resonance imaging confirmed effusion in the joint. Arthroscopy revealed that the pin was prominent intraarticularly, and the adjacent infrapatellar fat pad with surrounding synovial tissue seemed to be abraded. The pins were removed under arthroscopic guidance and any pain or hemarthrosis disappeared thereafter.