Bending strength and stress distribution of the interlocking intramedullary nails with high-thread wooden club-shaped nails versus traditional nails / 中国组织工程研究

ABSTRACT

BACKGROUND:Interlocking intramedullary nailing is a main method for bone fractures,but traditional static intramedullary nails usually lead to nail breakage and loosening.Thereafter,we design a novel high-thread wooden club-shaped screw (HTWCSS) and explore its mechanical properties.OBJECTIVE:To measure the bend strengths of HTWCSS,analyze its stress distribution,and to evaluate its biomechanical properties,thereby providing theoretical basis for its clinical application.METHODS:The bend strength of HTWCSS and traditional nails were measured via three-point bending experiments.Transverse fractures of the middle tibia were simulated using finite element method,and then the force and stress distribution of the two different nails were analyzed.RESULTS AND CONCLUSION:(1) The average maximum load of HTWCSS was 3.52 kN and 1.81 kN at span of 20 mm and 30 mm,respectively,which were larger than those of the traditional nails.(2) The average maximum displacement and the stress of HTWCSS were smaller than those of the traditional screws in finite element analysis,and the stress distribution was relatively dispersed.(3) The average maximum axial displacement and stress HTWCSS,traditional interlocking screws,wooden club-shaped screws and traditional screws were 131 MPa and 3.27 mm,162 MPa and 4.07 mm,26.5 MPa and 0.323 mm,and 34.3 MPa and 0.407 mm,respectively.(4) These results suggest that HTWCSS has relative high bend strength,and it is able to disperse stress and improve fatigue strength bend strength,further reduce screw broken.