Laser-induced nanostructures on titanium surfaces ensure osseointegration of implants in rabbit femora

Abstract

The lifetime of orthopedic prostheses is determined i.a. by the quality of their osseous fixation. Numerous surface modification techniques have been developed to improve the ingrowth of implants into the surrounding bone. These strategies aim at an increase of surface area to allow for an enhanced osseointegration, i.e. a functional connection between bone and implant. In the present study, a laser-based nanostructuring technique has been able to generate real nanostructures with cavities between 20–30 nm on cylindrical titanium alumina vanadium (TiAl6V4) alloy implants either coated with titanium niobium nitride (TiNbN) or titanium plasma spray (TPS) which were implanted into rabbit femora. In general, all implants appeared to be osseointegrated and well anchored in the bone. There were no differences in the pull-out forces applied to the untreated in comparison to the laser-irradiated implants. On the TPS cylinders obvious abrasive marks were left following the process of im- and explantation. However, the laser-induced nanostructures seemed to be resistant to damage. TPS-coated implants appeared to be more tightly anchored in the bone than TiNbN-coated cylinders in terms of bone-to-implant contact (BIC). There also were no differences in the bone / tissue volume ratio when comparing untreated to laser-irradiated implants. Taken together, nanostructured titanium surfaces are biocompatible and ensure a bony ingrowth. Nonetheless, the presence of nanostructures apparently has no further influence on the fixation of the implants in rabbit femora. Consequently, the optimal surface roughness as well the size and pattern of micro- and nanostructures of implants still requires further investigation.