Evaluation of Nitinol for Use as a Material in the Construction of Orthopaedic Implants

摘要

Certain characteristics of alloys of titanium and mixed (Nitinol) suggest that they may be superior materials from which to fashion Orthopaedic implants. Previous studies revealed that these alloys possess a critical transition temperature (TTR) over which the alloys undergo a highly unique electronic change and atomic repositioning associated with drastically altered mechanical properties such as elastic modulus and yield strength. Furthermore, When nitinol alloys are plastically deformed below the TTR, they are capable of reversible and forceful total recovery of shape when heated to temperatures exceeding the TTR. This study investigated the bio-compatibility of nitinol alloys and the ability of these alloys to display their 'shape memory' properties in vivo. All tests concerned with the biologic acceptability of the nitinol alloys showed no adverse tissue reaction to the nitinol alloy when compared to titanium and 316-L stainless steel. Nitinol bone plates containing a strain guage were manufactured. These plates were pre-stressed below the TTR and held in a pre-stressed manner until applied to the femora of sheep, after which the restraining device was removed allowing the alloy to return to its original shape.