I-X-ray :

Radiogiaphic examination oflhe aiYcciecl knee should include full-length, weight-bearing radiographs; antcroposterior and lateral radiographs ofthe knee; and Merchant view of the patella [axial (sunrise) view with the knee in 45 degrees of llexionjfio).

Comparison of serial radiographs is essential in the evaluation of prosthetic loosening (84).

-Radiugraphic signs of loosening include:

a-Development of a metal-cement lucency.

b-Progressive   widening   of   the   cement-bone   or   bone-prosthesis

interface.
c-Cement fragmentation under a component.                                         -..-._.......

e-Periprosthetic fracture or defect (84)..

The identification and interpretation of rad.iolucent lines are confusing to the point that their analysis is probably meaningless, unless the radiolucency is complete and-progressive, a circumstance usually accompanied by clinical symptoms (5).

In plain radiography, widening of the interface between bone and cement on serial films giving rise to a lucent line between prosthesis and the cement, is considered the bes^f sign of loosening (83).

1 lowever. lucent lines are a frequent finding and are known to be present in 70±100% of all knee arthroplastics, regardless of symptoms (83).

The same appearance of the widened interface may be present (or either septic or aseptic loosening so clinical and laboratory data and, ultimately joint aspiration are necessary to diagnose infection (84).