Aspect radiologique des descellements de protheses de hanches cimentees: étiologie mécanique, septique ou granulomateuse?

Radiologic diagnosis of hip prosthesis loosening is based on the evaluation of each component (prosthesis, cement, bone) and of their interfaces. Both the prosthesis and the cement may deteriorate and the prosthesis/cement interface or cement/bone interface may become abnormal in prosthesis loosening of any etiology. In contrast, the aspect of the bone changes (erosion, periostitis) and their distribution vary according to the condition etiology. It appears from a retrospective study of 50 cases of chronic hip prosthesis loosening that the most specific signs for infection are unsharp bone resorption and acute-like or multifocal periostitis. In granulomatous loosening, bone resorption is sharp (as in mechanical loosening), but its distribution is not conform to the prosthesis shape (as in septic loosening), and periosteal changes are not observed.