Imaging evaluation of periprosthetic loosening: A primer for the general radiologist

Figure 4 Plain radiographs and corresponding single-photon emission computed tomography/computed tomography of tibial component loosening. A–D: This is a recent case within our institution demonstrating the capability of single-photon emission computed tomography (SPECT)/computed tomography (CT) in diagnosing periprosthetic loosening. Initially, anteroposterior (A) and lateral (B) radiographs were performed to investigate the cause of right sided knee pain 8 years after cemented primary total knee replacement. The radiographs did not display typical signs of loosening or other abnormalities that could explain the patient’s symptoms. In addition, inflammatory markers were normal and clinical examination was unremarkable. Aseptic loosening was suspected and advanced imaging in the form of SPECT/CT was acquired. Coronal (C) and sagittal (D) SPECT/CT images demonstrate increased radiotracer uptake along the inferior aspect of the tibial base plate both medially and laterally but particularly posteromedially (white arrows). On the basis of the SPECT/CT image findings in conjunction with the clinical history, exam and blood markers, a diagnosis of aseptic loosening was made. The patient opted to undergo a revision total knee replacement at an alternative private institution.