 Introduction/Background Total knee arthroplasty (TKA), primarily used to treat pain and improve function in patients with symptomatic advanced knee osteoarthritis, is the most commonly performed joint replacement procedure in the United States [1,2]. In 2012, >670,000 knee replacement procedures were performed in the United States [3], which represents an increase of 86% since 2003 [4]. It is estimated that 4 million patients in the United States are currently living with a knee replacement [5]. By 2030, it is estimated that the annual demand for primary TKA will grow by 673% to 3.48 million [6]. Factors contributing to the rising number of TKAs include population growth; aging and increased longevity of the population; expanded indications for performing TKA, especially in individuals >65 years of age; obesity; decline in postprocedure complications; and increased patient demand [7]. Special Imaging Considerations In some patients with knee arthroplasties, repeated hemarthroses are caused by synovial hyperemia or true arteriovenous malformations. These patients can be successfully diagnosed with angiography and treated with embolization. In rare instances, geniculate and popliteal vessel injuries may occur during surgery [15]. A recent study reports single-photon emission CT (SPECT)/CT arthrography with Tc-99m sulfur colloid has a high diagnostic accuracy (97%) in the evaluation of loosening of both hip and knee arthroplasties in patients with persistent postprocedural pain [16]. Barnsley et al [17] also found arthrography with SPECT/CT to be an accurate means of identifying aseptic prosthetic joint loosening. aPenn State Milton S. Hershey Medical Center, Hershey, Pennsylvania and Uniformed Services University of the Health Sciences, Bethesda, Maryland. bPanel Chair, Mayo Clinic Arizona, Phoenix, Arizona. cUniversity of Wisconsin School of Medicine and Public Health, Madison, Wisconsin. dPenn State Health Milton S. Hershey Medical Center, Hershey, Pennsylvania.
Imaging After Total Knee Arthroplasty.  Introduction/Background Total knee arthroplasty (TKA), primarily used to treat pain and improve function in patients with symptomatic advanced knee osteoarthritis, is the most commonly performed joint replacement procedure in the United States [1,2]. In 2012, >670,000 knee replacement procedures were performed in the United States [3], which represents an increase of 86% since 2003 [4]. It is estimated that 4 million patients in the United States are currently living with a knee replacement [5]. By 2030, it is estimated that the annual demand for primary TKA will grow by 673% to 3.48 million [6]. Factors contributing to the rising number of TKAs include population growth; aging and increased longevity of the population; expanded indications for performing TKA, especially in individuals >65 years of age; obesity; decline in postprocedure complications; and increased patient demand [7]. Special Imaging Considerations In some patients with knee arthroplasties, repeated hemarthroses are caused by synovial hyperemia or true arteriovenous malformations. These patients can be successfully diagnosed with angiography and treated with embolization. In rare instances, geniculate and popliteal vessel injuries may occur during surgery [15]. A recent study reports single-photon emission CT (SPECT)/CT arthrography with Tc-99m sulfur colloid has a high diagnostic accuracy (97%) in the evaluation of loosening of both hip and knee arthroplasties in patients with persistent postprocedural pain [16]. Barnsley et al [17] also found arthrography with SPECT/CT to be an accurate means of identifying aseptic prosthetic joint loosening. aPenn State Milton S. Hershey Medical Center, Hershey, Pennsylvania and Uniformed Services University of the Health Sciences, Bethesda, Maryland. bPanel Chair, Mayo Clinic Arizona, Phoenix, Arizona. cUniversity of Wisconsin School of Medicine and Public Health, Madison, Wisconsin. dPenn State Health Milton S. Hershey Medical Center, Hershey, Pennsylvania.