Abstract:

Objective　To evaluate the stability of new Nickel titanium memory alloy three-corner fixator in treatment of midfoot injury and measure the changes of plantar pressure of the lateral column dislocation by three different implants to provide experimental reference in selecting implants and evaluate the biomechanical properties of those implants．Methods　Six fresh foot specimens were made into the models of the lateral column dislocation，which were fixed with Nickel titanium memory alloy three-corner fixator，the bridge plate and 2mm K-wire in turn. After the loading of 600 N，the changes of the plantar pressure in forefoot were measured by the method of the Tekscan Evolution handle pressure system．During the experiment, axial compression was performed with ElectroForce®3510 series test instruments. The compression stiffness of each bone-fixation combination was calculated and statistically analyzed.   Results   While the tarsometatarsal joint fracture dislocation was fixated by those there different kind of implants, the pressure under the fourth and fifth tarsometatarsal joints would all increased; the peak pressure under the second and third metatarsal head would all decrease, and differences were statistically significant（P＜0.05）．Nickel titanium memory alloy three-corner showed the statistical significant difference compared with the normal state（P>0.05）. There was no statistically significance between the compression stiffness of the three implants before fatigue test. The compression stiffness of K-wire group was decreased with significance.  Conclusion   Nickel titanium memory alloy three-corner fixator would help plantar pressure of the forefoot return to the normal state. The stability of the Nickel titanium memory alloy three-corner fixator is favored to meet the special biomechanical needs, which lays the foundation for its clinical use.

Key words: Nickel titanium memory alloy three-corner fixator, 　Midfoot injury；　Biomechanical；Plantar pressure