RESUMEN
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.