Influence of disodium (1-hydroxythylidene) diphosphonate on bone ingrowth into porous, titanium fiber-mesh implants.

The influence of disodium (1-hydroxythylidene) diphosphonate on the bonding between bone and porous, titanium fiber-mesh implants was studied. Rectangular, porous, titanium fiber-mesh implant (15 x 10 x 2.4 mm) were implanted into the tibial bone of mature male rabbits. The rabbits were divided into six groups. Disodium diphosphonate was administered daily by subcutaneous injection to groups 1-5. Groups 1-4 received doses of 5.0, 2.5, 1.0, and 0.1 mg per kilogram of body weight per day for 8 weeks, respectively. Group 5 received a dose of 5 mg per kilogram of body weight per day for 4 weeks. Group 6 (control group) was given saline injections. At 8 weeks after implantation, the rabbits were killed. The tibiae containing the implants were dissected out and subjected to detachment tests. The failure load, when an implant became detached from the bone or when the bone itself broke, was measured. The interface of the bone and implant was investigated by Giemsa surface staining and contact microradiography. Giemsa surface staining and contact microradiography showed that porous implant bonding to bone tissue was inhibited by a high dose of disodium diphosphonate in groups 1, 2, and 5. Soft tissue was observed at the interface. In groups 3, 4, and 6, bone tissue ingrowth was observed at the interface between the porous implant and bone tissue. Growth of bone into the porous fiber-mesh implant of a cementless prosthesis is possible if a low dose of diphosphonate below 1.0 mg per kilogram of body weight is given subcutaneously.