[The design and comparative biomechanical study of TDP&CS].

A new internal fixation device(TDP&CS) for subtrochanteric fracture of the femurs was designd and compared with Gamma nail and Jewwet nail biomechanically. A model with 5 mm bone deficit presenting as fracture fixation (mFF) and a model with nail holes presenting as fracture healed and nails removed(mFHNR) were designed. Four-point anti-bent test, anti-axial compression test and anti-torsion test were continually performed on mFF, and four-point anti-bent and anti-torsion tests were performed on mFHNR. The results showed that in mFF group, TDP&CS was stronger than Jewwet nail(P < 0.05) in all the three tests, but it was not statistically different from Gamma nail. In mFHNR group, TDP&CS had better features than Gamma nail and Jewett nail in anti-bent and anti-torsion tests (P < 0.05). These data indicate that TDP&CS is a good internal fixation device for subtrochanteric fracture of the femurs, it is as good as Gamma nail and better than Jewett nail in fixing the fracture, and its nail holes could do less injury to the bone as compared with those of the Gamma nail and Jewett nail.