Journal article

Peri-implant bone adaptations to overloading in rat tibiae: experimental investigations and numerical predictions

Objectives(i) To assess the effects of mechanical overloading on implant integration in rat tibiae, and (ii) to numerically predict peri-implant bone adaptation. Materials and methodsTranscutaneous titanium implants were simultaneously placed into both tibiae of rats (n=40). After 2weeks of integration, the implants of the right tibiae were stimulated daily for 4weeks with loads up to 5N (corresponding to peak equivalent strains of 3300500 epsilon). The effects of stimulation were assessed by exvivo mechanical tests and quantification of bone mineral density (BMD) in selected regions of interests (ROIs). Specimen-specific finite element models were generated and processed through an iterative algorithm to mimic bone adaptation. ResultsBilateral implantation provoked an unstable integration that worsened when mild (2-4N) external loads were applied. In contrast, a stimulation at 5N tended to counterbalance the harmful effects of daily activity and, if applied to well-integrated specimens, significantly augmented the implants' resistance to failure (force: +73% P<0.01, displacement: +50% P<0.01 and energy: +153% P<0.01). Specimen-specific numerical predictions were in close agreement with the experimental findings. Both local and overall BMD variations, as well as the implants' lateral stability, were predicted with small errors (0.14gHA/cm(3) and 0.64%, respectively). ConclusionsThe rats' daily activity detrimentally affects implant integration. Conversely, external stimulations of large magnitudes counterbalance this effect and definitively improve integration. These changes can be predicted using the proposed numerical approach.


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