[Biomechanic study on length of plate in treatment of tibial shaft fracture].

OBJECTIVE

To research the biomechanical effect of different length bone plates on treatment of tibial shaft fracture.

METHODS

Forty-five tibia specimens from fresh adult corpse (20-40 years old) were donated (30-38 cm in length, 34 cm on average) and were divided into 3 groups randomly (n = 15). Under the following three conditions, the experiment was made separately. Compression stress-strain indexes of whole tibia were determined under the reverse, three spots curving and compression. The vertical elastic strain was 0-1 000 N, the reverse angle was 0-3 degrees, and three bending stress was 0-400 N. Then the center-section squint non-damage bone fracture model was made, fracture was fixed by 6, 10, 14 stainless steel AO LC-DCP, respectively. The compression stress-strain indexes were determined under reverse angle, three spots curving and compression, statistical analysis was done.

RESULTS

The vertical direction strain value of 6, 10 and 14 hole steel plate under vertical compressions, was 0.449 +/- 0.241, 0.093 +/- 0.003, 0.139 +/- 0.005, respectively; showing significant difference between 10 and 14 hole steel plates and 6 steel plate (P < 0.01) and no significant difference between 10 and 14 hole steel plate (P > 0.05). The lateral strain value of 6, 10 and 14 hole steel plate was 0.120 0 +/- 0.000 4, 0.127 5 +/- 0.010 0, 0.237 0 +/- 0.000 6 respectively, indicating a significant difference between stell plates of 6 and 10 hole and 14 hole steel plate (P < 0.01) and no difference between 6 and 10 hole steel plate (P > 0.05). The torque of 6, 10 and 14 hole steel plate was (5.066 +/- 2.715) x 10(-3), (5.671 +/- 2.527) x 10(-3) and (4.570 +/- 2.228) x 10(-3) Nm, respectively and three spot curving vertical direction strain value was 0.049 +/- 0.009, 0.124 +/- 0.017, 0.062 +/- 0.009, respectively. There were significant differences between various steel plates (P < 0.01).

CONCLUSION

For the fixation of tibial oblique fracture, 14 hole steel plate's stabilities of anti-vertical compression, anti-reverse and anti-curving are better than those of 6 hole steel plate under the condition of the same material quality, thickness, width and screw quantity used.