TiNi shape memory clamps with optimized structure parameters

The different treatments of TiNi shape memory alloys applied as a material for so-called TiNi clamps and their influence on substructure parameters and deformation behaviour are discussed. The forces generated in fine-grained materials with higher dislocation density are stable after the cooling of the clamp to body temperature, which is a necessary condition for stable fixation of bone fragments. The forces generated and reversible strains depend on the substructure state and system stiffness parameter. The ''yield point'' and the ''elastic moduli'' are modified by controling the B2/B19' interface mobility. The mechanical parameters obtained after annealing at 400 and 500 degrees C, respectively, following the 15% cold-working reduction are optimal for the TiNi clamp design. The TiNi clamps with optimal properties have been used in a total of 68 patients. The new TiNi clamps enhance the fixation of the bone fragments involved, helping to prevent redislocation and provide the ability for earlier active rehabilitation.