Systemic alendronate prevents resorption of necrotic bone during revascularization. A bone chamber study in rats

BACKGROUND Avascular necrosis of bone (osteonecrosis) can cause structural failure and subsequent deformation, leading to joint dysfunction and pain. Structural failure is the result of resorption of necrotic bone during revascularization, before new bone has formed or consolidated enough for loadbearing. Bone resorption can be reduced by bisphosphonates. If resorption of the necrotic bone could be reduced during the revascularization phase until sufficient new bone has formed, it would appear that structural failure could be avoided. METHODS To test whether resorption of necrotic bone can be prevented, structural grafts were subjected to new bone ingrowth during systemic bisphosphonate treatment in a rat model. RESULTS In rats treated with alendronate the necrotic bone was not resorbed, whereas it was almost entirely resorbed in the controls. CONCLUSION Systemic alendronate treatment prevents resorption of necrotic bone during revascularization. In patients with osteonecrosis, bisphosphonates may therefore prevent collapse of the necrotic bone.