Late bullet migration into the knee joint.

A 25-year-old active-duty police officer was found to have an intra-articular foreign body on radiographic study of his left knee joint. He had a gunshot wound to the midthigh 54 months prior to the presentation of symptoms. The bullet was lodged in the soft tissue without involving neurovascular structures. The patient complained of limited range of motion of the joint and a "rattle" sensation of the knee. Arthroscopically, a deformed metallic foreign body was found and retrieved. There was no injury inside the joint related to the loose body. These findings were consistent with a migrating bullet from the midthigh to the knee joint. The patient recovered uneventfully and returned to work.