Bone allografts pretreated with a bisphosphonate are not resorbed

Bisphosphonates bind to bone surfaces and inactivate osteoclasts when they start to resorb the bone. Therefore, immersion of a bone graft in a bisphosphonate solution before implantation may protect it from resorption. We implanted frozen cancellous bone allografts into bilateral bone chambers for 6 weeks in 10 rats. One graft in each pair had been immersed in an alendronate solution (1 mg/mL) for 10 minutes, and then rinsed in saline. Controls underwent the same treatment with saline only. Results were evaluated with histomorphometry. Control grafts were almost entirely resorbed, but alendronate-treated grafts seemed intact. In the treated specimens, two thirds of the space behind the bone ingrowth frontier consisted of graft or host bone, but in the controls, only one fifth. Local graft treatment with a bisphosphonate before insertion seems to be risk-free, and may prevent mechanical graft failure due to resorption in patients.