ABSTRACT
<p><b>OBJECTIVE</b>To study the biomechanical characteristics of Ni-Ti shape-memory alloy-enclosed interlocking intramedular nail Ni-Ti En for clinical application.</p><p><b>METHODS</b>Six transverse fractures were induced in 6 fresh humeral shafts and fixed with Ni-Ti En, plate, interlocking intramedullary nail, and Ender nail, respectively. The specimens then underwent stress analysis for comparison of the bending strength, twisting force, and flexibility.</p><p><b>RESULTS</b>The bending strength of Ni-Ti En was not significantly different from that of the plate and better than ender's nail; the twisting force of the interlocking intramedullary nail was comparable with the plate, but better than Ender nail.</p><p><b>CONCLUSION</b>Ni-Ti Enpossess good biomechanical property to meet the demand of osteosynthesis, and its less stress protection, freedom of distant nail locking, flexibility and stable fixation may accelerate fracture healing.</p>