Effect of disodium etidronate (EHDP) on bone ingrowth in a porous material

This study evaluated the effect of disodium etidronate (EHDP) on biomechanical and histologic characteristics of bone ingrowth in a porous material. EHDP was administered parenterally to six adult mongrel dogs at a dose of 2 mg/kg/day for eight weeks. Six additional dogs served as controls and were injected with saline. Porous titanium fiber composites were inserted into the proximal humeri and the left olecranons of all animals after the first four weeks of treatment. Upon completing a total of eight weeks of treatment, all animals were sacrificed and the bone-porous implant interfacial shear strength was determined by a pull-out test to failure. Mean shear strength of fixation for the EHDP-treated group was reduced by 76% compared to the control group (p less than 0.001). Bone ingrowth was mineralized in all of the control specimens. Mineralization of tissue ingrowth was inhibited, however, in all specimens from EHDP-treated animals. These findings suggest that cementless skeletal fixation of porous-coated implants by bone ingrowth may be delayed or prevented by the administration of EHDP.