RESUMEN
Objective To investigate the biomechanical properties of transverse fractured femurs when fixed by TiNi shapememory alloy embracing plate (TiNi SMA), limitedcontact dynamic compression plate (LCDCP) and static interlocking intramedullary nail (SIiN), respectively, so as to provide the theoretical evidence for orthopedic surgeons in clinical application. Methods Eight pairs of cadaveric femurs were used with one side randomly fixed by TiNi SMA and SIiN and the other side fixed by LC-DCP. Then the axial compression test, threepoint bending test, and torsion test were conducted. Results For axial compression test, the strains of TiNi SMA group were greater than those of LC-DCP group and SIiN group (P0.05). The displacements of TiNi SMA group were greater than those of LC-DCP group and SIiN group (P0.05). For three-point bending test, the displacements of TiNi SMA group were greater than those of LC-DCP group and SIiN group (P0.05). For torsion test, the torsion angels of TiNi SMA group were similar to those of SIiN group (P>0.05), but the torsion angles of LC-DCP group were smaller than those of TiNi SMA group（≥3 N•m）and SIiN group (P<0.05). Conclusions When the fractured femurs are fixed by three internal fixation devices, the stability of TiNi SMA group is weakest, SIiN group being better, and LCDCP group being best. The axial micromotion in TiNi SMA group can promote the healing of fracture.