Anchorage of femoral implants visualized by modified computed tomography.

Metallic implants produce a great deal of artifacts in standard CT images. These artifacts cover tissue structures and impede visualization of the anchorage of the implant within the bone. Thus a modified CT procedure has been developed to permit reconstructions free from artifacts. It is an iterative procedure using a maximum of measured projection data. Using this modified CT technique, the anchorage of a titanium-alloy femoral prosthesis implanted without cement was examined. Good contact of the implant with the cortical bone has documented. This promises good initial stability. The CT examinations were performed by using a special-purpose CT scanner. It is hoped that the modified CT technique will allow a quantification of bony tissue in the close vicinity of implants and thus provide a non-invasive procedure that will allow the long-term stability of implants to be evaluated.