REINTEGRATION OF MOBILIZED TITANIUM IMPLANTS - AN EXPERIMENTAL-STUDY IN RABBIT TIBIA

The possibility of re-establishing a rigid bone-implant fixration, i.e . osseointegration, after mechanical loosening of titanium implants, w as evaluated in the rabbit tibia. Implants were inserted to engage eit her one (10 mm long, n=24) or two (16 mm long, n=24) cortical layers a nd were allowed to heal for six weeks. A re-entry was then made and 12 test implants in each group subjected to a reverse torque procedure u ntil the integration failed. The remaining nonrotated 24 implants were left as controls. Thereafter all implants were allowed to heal for an additional period of six weeks. At the end of the 12 weeks, the degre e of integration was assessed by measuring the removal torque for six test and six control implants in each group of implant lengths. Histom orphometric measurements were also performed on ground sections of the remaining test and control implants. A statistically significant high er removal torque was observed for the monocortical test implants than for the corresponding control implants. No differences were seen for the bicortical implants of either kind, however, no Morphological diff erences could be revealed either, when comparing monocortical and bico rtical test and control implants. These results indicate that osseoint egrated implants that have been mobilized due to a traumatic disruptio n of the bone-implant interface, may reintegrate if allowed to heal fo r an additional period of time.