| Objectives:The femoral neck fracture is very common in clinic. It accounts for 3.6% in all sorts of fractures. Ages have the high risk of this illness, especially to the femal. Its incidence grows fastly with the society aging and moden-traffic developing. Compare to other fractures, it has some special features: most of it's patients are ages, its'blood flow is special; the femoral neck bears weightful shear stress. So it's rate of unuion and necrosis is highly. Since Smith-peterson invented the three-spade pin to treat the femoral neck fractrue, a half of century fleeted, the internal fixation advanced fastly, but there is not a kind of fixation can decrease the necrosis rate of femoral head obviousely. We carried out this specimen experiment to observe the capability of torsion and pressure which treatment of the femoral neck fracture by two kinds of nails. And we expect that it could grading-up the vitodynamics contrive of internal fixation, improve union of fracture and provide base on the clinical practice.Methods:Sixteen adult collection which below hip bone were separated four groups ranly. Make fracture models of Pauwels 70°without defeating the articulation coxae. Internal fixatie the fractures by the method which apply three nails to heal fracture. One nail was near the hpy-cortical bone, the second nail was near the pone cortical bone and the last one was compacted"inv-triangle"with the other twe nails. The angle of the needing is 135°to the shaft of femur at least. Two groups (A,B group) were treated with right screw nails, the other two groups (C,D group) were treated with left screw nails. Dislodge the fems above condyle and protect the caput femoris. The two groups (A,C group) were experimented by rotation test and the other two groups (B,D group) were experimented by pressure test. The data were analyses by statistics.Results:1 The general state: The nut-locking device was fastness and no allaxis or cinch. The caput femoris was not disrupt. The shaft of femur was not fracture. The nails was not abruptly.2 Rotation test2.1 The moment that left fracture treated with right screw nails (3.832±0.813N×m) was bigger than it that treated with left screw nails (2.785±0.741N×m) (P<0.05) when the intortion angle reached 2°. The moment that left fracture treated with right screw nails (5.865±1.558N×m) was bigger than it that treated with left screw nails (4.139±0.944N×m) (P<0.05) when the intortion angle reached 3°. And the moment that left fracture treated with right screw nails (8.613±2.009N×m) was bigger than it that treated with left screw nails (6.123±1.832 N×m) (P<0.05) when the intortion angle reached 4°.2.2 The moment that right fracture treated with right screw nails (2.433±0.530N×m) was smaller than it that treated with left screw nails (3.638±0.767N×m) (P<0.05) when the intortion angle reached 2°. The moment that left fracture treated with right screw nails (4.192±1.205N×m) was smaller than it that treated with left screw nails (5.885±1.383 N×m)(P<0.05) when the intortion angle reached 3°. And the moment that left fracture treated with right screw nails (6.535±1.577N×m) was smaller than it that treated with left screw nails (9.316±2.418 N×m) (P<0.05) when the intortion angle reached 4°.3 Pressure test3.1 The bias that left fracture treated with right screw nails (0.749±0.180mm) was equivalency with it that treated with left screw nails (0.657±0.173mm) (P>0.05) when the pressure reached 450N. The bias that left fracture treated with right screw nails (1.121±0.294mm) was equivalency with it that treated with left screw nails (1.214±0.358mm) (P>0.05) when the pressure reached 600N. The bias that left fracture treated with right screw nails (1.578±0.359mm) was equivalency with it that treated with left screw nails (1.673±0.274mm) (P>0.05) when the pressure reached 750N.3.2 The bias that right fracture treated with right screw nails (0.683±0.182mm) was equivalency with it that treated with left screw nails (0.645±0.196mm) (P>0.05) when the pressure reached 450N. The bias that right fracture treated with right screw nails (1.182±0.247mm) was equivalency with it that treated with left screw nails (1.235±0.276mm) (P>0.05) when the pressure reached 600N. The bias that left fracture treated with right screw nails (1.755±0.322mm) was equivalency with it that treated with left screw nails (1.694±0.331mm) (P>0.05) when the pressure reached 750N.Conclusion:1 The femoral neck fracture model and the internal fixation model remaining articulatio coxae were duplicate successfully.2 The effect that treat the left femoral neck fracture with right screw nails was better than treat with left screw nails. And the effect that the right femoral neck fracture with left screw nails was better than treat with right screw nails.3 The two kinds of screw nails have the same capability of pressure.4 It is initial consider that the left screw nails is a good kind of vitodyamics internal fixation device which treat with right femoral neck fracture.
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