ABSTRACT
BACKGROUND: Interlocking intramedullary nails(SliN)is frequently used to treat femoral fracture.Routine pulling and compression and postoperative motorization are important for fracture healing.To improve fracture healing rate has been focused using various factors.OBJECTIVE: To explore the biomechanical performance of static SliN in fixation of femoral fracture,and the effect on fracture healing.METHODS: A total of 8 pairs of femurs from adult cadavers immersed in formalin were used to prepare models of midpiece transverse fracture.The fracture was respectively fixed using static SliN,TiNi shape-memory sawtooth-arm embracing internal fixator(TiNi SMA),and dynamic compression plate(DCP).The anti-compression,anti-bending,and anti-torsion rigidity were measured,and the stress shielding rate was calculated.RESULTS AND CONCLUSION: SliN was similar to DCP group in anti-compression rigidity and anti-bending rigidity(P > 0.05),but the anti-torsion was lower than DCP group(P<0.05).Compared with TiNi SMA group,SliN displayed greater anti-compression rigidity and anti-bending rigidity(P<0.05),but similar anti-torsion(P > 0.05).SliN was similar to DCP group in stress shielding rate(P>0.05),but significantly greater than TiNi SMA group(P<0.01).The biomechanics of SliN was stable,but the stress shielding rate was high.Changing static interlocking into dynamic interlocking in time is necessary in clinic to promote fracture healing.