Metastatic Carcinoma as an Unusual Cause of Knee Pain After Total Knee Arthroplasty

ommon causes of pain after total knee arthroplasty include component loosening, infection, instability, extensor mechanism dysfunction, stress fracture, or periprosthetic osteolysis1. Extra-articular causes of pain include radiculopathy, hip disease, vascular disease, or tendonitis. Metastatic disease as the cause of knee pain after total knee arthroplasty has rarely been reported. A thorough history and physical examination can often identify the nature and cause of the pain. The traditional diagnostic workup for knee pain after total knee arthroplasty includes radiographs (both stress and plain radiographs), serology (C-reactive protein level and erythrocyte sedimentation rate), and knee aspiration. Nuclear medicine scans are occasionally helpful when other tests are negative1. We report the case of a patient who presented to our office with knee pain following total knee arthroplasty. This patient was later discovered to have metastatic cholangiocar-cinoma to the distal aspect of the femur as the cause of the knee pain. The family of the patient was informed that data concerning his case would be submitted for publication. Case Report Asixty-nine-year-old man underwent a right total knee ar-throplasty with cement and with a posterior stabilized mobile-bearing prosthesis (PFC Sigma Rotating Platform; DePuy, Johnson and Johnson, Warsaw, Indiana) for end-stag