[Biomechanical comparison of three methods of internal fixation for distal femoral fractures].

OBJECTIVE: To compare the biomechanics of three internal fixations for distal femoral fractures,and to choose suitable clinical internal fixation according to experimental date. METHODS: The fracture models of femoral condydle were made on 12 fresh cadaver femurs (C1 type of AO classification). The fractures were fixed by supracondylar intramedullary interlocking nails (A), L-shaped condyle plates (B) and compressed plates (C) respectively. The straining, displacement, rigidity and intensity of femoral supracondyla of the three internal fixations of distal femoral fractures were observed and analyzed by biomechanics. These three different internal fixation methods were compared by experimental stress analysis. These results were further confirmed by theoretical analysis using finite element method (FFM). RESULTS: Under the same load condition, supracondylar intramedullary interlocking nail fixation was the best on the intensity and rigidity,while for compressed plate and L-shaped condyle plate, the femoral condyle intensity and rigidity were worse (P < 0.05). There were distinct differences in stress and displacement among three methods (P < 0.01). CONCLUSION: Supracondylar intermedullary interlocking nail is the best method among the three internal fixation methods. It has advantage such as screw location, solid fixation and less complication. It is a good internal fixation method for distal femoral fracture.

Effects of various planting densities on dynamic growth rhythm and root yield of Isatis indigotica / 中国中药杂志

<p><b>OBJECTIVE</b>To study the effects of various planting densities on dynamic growth and root yield of Isatis indigotica.</p><p><b>METHOD</b>The planting samples were collected to measure the growth period of each organ.</p><p><b>RESULT AND CONCLUSION</b>Under different planting densities, both main root length and breadth exhibited a trend of "fast-slow" by stages. However, the number of individual plant leaves were showed a trend of "slow-fast" on growth period. Meanwhile, the leaf length and breadth were exhibited a trend of "increase-decrease". The increase of dry leaf, dry root and whole plant dry matter was faster during the period of 65-76 days after seeding. The differences of root and leaf yields under various densities were significant. Planting densities has a great effect on yield of root. It must be shown that there was a positive development between the individual plant and colony. According to the dry matter of root and leaf, treatment B (i.e., 7 cm x 25 cm) was good choice.</p>