A cadaver model was used to compare the sensitivity of fluoroscopically
guided radiographs with that of plain radiographs in revealing lucent lines
beneath the tibial component of an uncemented total knee arthroplasty and
subsidence of the component. Fluoroscopically guided radiographs allowed
accurate measurement of a lucent line that was one millimeter wide. Plain
radiographs were inadequate for the detection and measurement of these
lucent lines, leading to inaccuracy. Fluoroscopically guided radiographs
also allowed measurement of the distance between the tibial component and
radiopaque markers in the proximal part of the tibial metaphysis that was
reproducible to within one-half millimeter. Plain radiographs did not
provide a reproducible measurement of this distance. The relatively simple
technique of fluoroscopically guided radiography is recommended to detect
the presence and progression of radiolucent lines and the subsidence of
uncemented tibial components after total knee arthroplasty.