| Objective To campare the biomechanics performance of the compression screws of the proximal femoral nail (PFN), which placed different position in the neck of femur during the the surgical treatment of intertrochanteric fracture.Methods Five pairs of fresh cadaveric femur specimens were selected, which were created into A.O type A 1.1 intertrochanteric fracture.All femur were fixed by PFN, Each pair were divided into two groups. In test group, the two compression screws were located in mid-inferior 1/3 part of coronal plane of neck of femur. In control group, screws were in mid-superior 1/3 part. The experiment about broken ends of fractured bone included test of stress distribiution about broken ends and screws, opening angle, displace of contact face, maximum load. The load increased gradually from ON to 1000N. The maximum load were taken after the entotrochanter was rejected.Result 1. stress distribiution:straining of femur proximate wall structure in text group was less than that of control group, but straining of screws was on the contrary. So, it can concluded that screws suffered more stress in test group, which concentrated in femur proximate area. Complications, such as coxa adducta, have more probability in control group.2.opening angle:test group were significantly smaller than control group under the gradually increased load(P<0.01).3. displace of contact face:test group had 30.1%less than control group.Conclusion The compression screws of the PFN, which was used to operate on the surgical treatment of intertrochanteric fracture, had a better biomechanics performance by being placed in mid-inferior 1/3 part of coronal plane of neck of femur. It satisfies the demands that combined firmly fixation and functional exercise, which benefits the union of fracture in initial stage. And it could reduce the probability of complications obviously, such as coxa adducta.
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