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

Figure 2 Computed tomography scan of loose cemented acetabular component with comparison plain radiographs. This case displays the utility of computed tomography (CT) with metal artefact reduction in diagnosing periprosthetic loosening. The gentleman in this case was referred to the outpatient’s clinic by his family physician with complaints of gradually worsening pain and discomfort in the left hip. The patient’s blood markers were normal at the time of referral and examination findings were equivocal. A and B: Acetabular loosening in a cemented total hip arthroplasty was confirmed on initial plain radiography of the pelvis (A). However, characterisation with CT was required in this case to determine the extent of loosening and appropriately plan revision surgery (B). Both images were acquired on the same day. Although acetabular loosening is visible in Figure 2A around DeLee Charnley Zones 1 & 2, the extent of loosening and bony erosion is far clearer in Figure 2B (blue arrows). An approximate 10 mm rim of lucency was demonstrated on the CT scan which was not easily appreciated on the initial plain radiographs (yellow arrow). The patient proceeded to a successful revision hip arthroplasty following review of the CT images.