CT can be used to detect osteolysis and to determine the total volume of osteolytic lesions, particularly when metal reduction techniques are used [124]. CT is supported by Math et al [20] to look for osteolysis in patients with painful knee prostheses who have normal or equivocal radiographs and increased uptake on all 3 phases of a bone scan. Reish et al [67] found that only 17% of 48 lesions visible by CT were detected on radiographs. They suggested multidetector CT in cases in which osteolysis is expected, such as when there is aseptic loosening and gross polyethylene wear. CT allows the assessment of rotational positioning of the prosthesis components, which can affect patellofemoral tracking and varus/valgus ligamentous stability in flexion [125]. Imaging of rotational instability of a TKA is discussed in greater detail under Variant 5. There are varying reports on FDG sensitivity, specificity, and accuracy, which are likely in part related to nonuniform interpretation criteria and PET techniques. One overall estimate of FDG sensitivity, specificity, and accuracy in TKA is 96%, 77%, and 83%, respectively [126]. Although FDG is reportedly limited in evaluating patients with chronic knee pain after TKA [66,127], further advancements in FDG-PET may potentially be a promising tool in identifying prosthetic osteolysis [126]. Its exact role in the failed joint prosthesis; however, has yet to be determined. There is insufficient evidence to support routine use of FDG-PET/CT for assessment of instability. Fluoride PET/CT Whole Body Koob et al [128] noted a sensitivity of 95.00%, a specificity of 87.04% and an accuracy of 89.19% for the diagnosis of periprosthetic loosening of total hip and knee prosthesis with fluoride PET/CT. There is insufficient evidence to support routine use of fluoride PET/CT for assessment of instability.
Imaging After Total Knee Arthroplasty. CT can be used to detect osteolysis and to determine the total volume of osteolytic lesions, particularly when metal reduction techniques are used [124]. CT is supported by Math et al [20] to look for osteolysis in patients with painful knee prostheses who have normal or equivocal radiographs and increased uptake on all 3 phases of a bone scan. Reish et al [67] found that only 17% of 48 lesions visible by CT were detected on radiographs. They suggested multidetector CT in cases in which osteolysis is expected, such as when there is aseptic loosening and gross polyethylene wear. CT allows the assessment of rotational positioning of the prosthesis components, which can affect patellofemoral tracking and varus/valgus ligamentous stability in flexion [125]. Imaging of rotational instability of a TKA is discussed in greater detail under Variant 5. There are varying reports on FDG sensitivity, specificity, and accuracy, which are likely in part related to nonuniform interpretation criteria and PET techniques. One overall estimate of FDG sensitivity, specificity, and accuracy in TKA is 96%, 77%, and 83%, respectively [126]. Although FDG is reportedly limited in evaluating patients with chronic knee pain after TKA [66,127], further advancements in FDG-PET may potentially be a promising tool in identifying prosthetic osteolysis [126]. Its exact role in the failed joint prosthesis; however, has yet to be determined. There is insufficient evidence to support routine use of FDG-PET/CT for assessment of instability. Fluoride PET/CT Whole Body Koob et al [128] noted a sensitivity of 95.00%, a specificity of 87.04% and an accuracy of 89.19% for the diagnosis of periprosthetic loosening of total hip and knee prosthesis with fluoride PET/CT. There is insufficient evidence to support routine use of fluoride PET/CT for assessment of instability.