OBJECTIVETo compare the biomechanics of three internal fixations for distal femoral fractures,and to choose suitable clinical internal fixation according to experimental date.

METHODSThe fracture models of femoral condydle were made on 12 fresh cadaver femurs (C1 type of AO classification). The fractures were fixed by supracondylar intramedullary interlocking nails (A), L-shaped condyle plates (B) and compressed plates (C) respectively. The straining, displacement, rigidity and intensity of femoral supracondyla of the three internal fixations of distal femoral fractures were observed and analyzed by biomechanics. These three different internal fixation methods were compared by experimental stress analysis. These results were further confirmed by theoretical analysis using finite element method (FFM).

RESULTSUnder the same load condition, supracondylar intramedullary interlocking nail fixation was the best on the intensity and rigidity,while for compressed plate and L-shaped condyle plate, the femoral condyle intensity and rigidity were worse (P < 0.05). There were distinct differences in stress and displacement among three methods (P < 0.01).

CONCLUSIONSupracondylar intermedullary interlocking nail is the best method among the three internal fixation methods. It has advantage such as screw location, solid fixation and less complication. It is a good internal fixation method for distal femoral fracture.