Alendronate did not inhibit instability-induced bone resorption - A study in rats

Alendronate is a bisphosphonate that can decrease osteoclastic activity. It has been suggested as treatment for periprosthetic osteolysis. We used 48 rats, of which 32 had a prate implant on one tibia, to study the effect of alendronate on bone resorption at an unstable implant-bone interface. The p late has a handle on top, which can be grasped through the skin and turned, to create a sliding motion of a titanium surface against the underlying bo ne. This is known to result in bone resorption, which was studied by histom orphometry. Osmotic minipumps were used to administer alendronate at 0.063 mg/kg/day or saline. The systemic effect of the treatment was assessed by a shing the proximal metaphyses of the tibia of the contralateral unoperated leg. The ash-weight was increased in the alendronate-treated group by 43% ( p = 0.0001), corresponding to histological changes in the metaphyseal bone. There was no inhibition of the instability-induced bone resorption at the test surface by atendronate: bone was being resorbed and replaced by a tiss ue similar to a loosening membrane.