HISTOMORPHOMETRIC ANALYSIS OF THE RESPONSE OF RAT TIBIAE TO SHAPE-MEMORY ALLOY (NITINOL)

The bone reaction to nitinol (Ni-Ti), a metal with shape memory, and o ther materials inserted transcortically and extending into the medulla ry canal of rat tibiae was quantitatively assessed using an image proc essing system. The materials examined were implants, all of the same s hape and size, composed of nitinol, pure titanium (Ti), anodic oxidize d Ti (AO-Ti), a titanium alloy (Ti-6AI-4V) and pure nickel (Ni). While the other four implant materials were progressively encapsulated with bone tissues, Ni was encapsulated with connective tissues through the 168-day experimental period, and the Ni implants showed no bone conta ct at any time during the experimental period. Histometric analysis re vealed no significant differences among the tissue reactions to Ti, AO -Ti and Ti-6AI-4V, but Ni-Ti implants showed significantly (P < 0.01) lower percentage bone contact and bone contact area than any of the ot her titanium or titanium alloy materials. (C) 1996 Elsevier Science Li mited