INFLUENCE OF DISODIUM (1-HYDROXYTHYLIDENE) DIPHOSPHONATE ON BONE INGROWTH INTO POROUS, TITANIUM FIBER-MESH IMPLANTS

The influence of disodium (1-hydroxythylidene) diphosphonate on the bo nding between bone and porous, titanium fiber-mesh implants was studie d. Rectangular, porous, titanium fiber-mesh implants (15 x 10 x 2.4 mm ) were implanted into the tibial bone of mature male rabbits. The rabb its were divided into six groups. Disodium diphosphonate was administe red 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 da y for 8 weeks, respectively. Group 5 received a dose of 5 mg per kilog ram of body weight per day for 4 weeks. Group 6 (control group) was gi ven saline injections. At 8 weeks after implantation, the rabbits were killed. The tibiae containing the implants were dissected out and sub jected to detachment tests. The failure load, when an implant became d etached 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 con tact microradiography showed that porous implant bonding to bone tissu e was inhibited by a high dose of disodium diphosphonate in groups 1, 2, and 5. Soft tissue was observed at the interface. Ln groups 3, 4, a nd 6, bone tissue ingrowth was observed at the interface between the p orous implant and bone tissue. Growth of bone into the porous fiber-me sh implant of a cementless prosthesis is possible if a low dose of dip hosphonate below 1.0 mg per kilogram of body weight is given subcutane ously.