ObjectiveTo explore the mechanical stability of the three-dimensional (3-D) external fixator for osteoporotic fracture so as to provide the biomechanical basis for clinical application. MethodsForty-five fresh frozen adult tibial specimens were selected to rapidly prepare the extracorporal tibia osteoporotic fracture models, and were randomly divided into 3 groups (n=15). Fractures were fixed with 3-D external fixators (3-D external fixators group), intramedullary nails (intramedullary nail group), and plate (plate group) respectively. Five specimens randomly from each group were used to do axial compression test, three-point bending test, and torsion test with microcomputer control electronic universal testing machine, then the mechanical parameters were calculated. ResultsIn the axial compression test, the displacement of 3-D external fixator group and intramedullary nail group were shorter than plate group, showing significant differences (P<0.05); but no significant difference was found between 3-D external fixator group and intramedullary nail group (P>0.05). In the three-point bending test and torsion test, the deflection and the torsional angle of 3-D external fixator group and intramedullary nail group were smaller than plate group, showing significant differences (P<0.05); but no significant difference was found between 3-D external fixator group and intramedullary nail group (P>0.05). ConclusionThe 3-D external fixator can fix fracture three-dimensionally from multiple plane and it can offer strong fixing. It is biomechanically demonstrated to be suitable for osteoporotic fracture.
ObjectiveTo determinate the concentration of isonicotinyl hydrazide (INH) in the hydrothorax and thereby increase the drug concentration of the hydrothorax to enhance the anti-tuberculosis efficacy through experiments. MethodsBetween February and June 2009, we used high performance liquid chromatography (HPLC) to determinate the concentration of INH in the hydrothorax of tuberculosis (TB) patients. The separation of sample was performed on Agilent ZORBAX SB-C18 (5 μm, 4.6 mm×2.5 mm) column with a fixed sample injection volume of 20 μL. The mobile phase was methanol-water (20︰80) at a flow rate of 1 mL/min. The ultraviolet detective wavelength was set at 254 nm; The column temperature was room temperature. ResultsIn the range of 0.25-10.00 μg/mL (r=0.998 9), moxi-floxacin showed a good linear relation in HPLC. The recoveries of moxi-floxacin at three concentrations (0.5, 5.0, and 10.0 μg/mL) were 97.95%, 100.64%, and 102.84%, respectively, with intra-day relative standard deviation (RSD) at 3.49%, 1.45%, and 2.03%, respectively and intra-day RSD at 3.85%, 5.68%, 4.15%, respectively. ConclusionThe measuring method adopted in the experiment can accurately determinate the concentration of INH in the hydrothorax with high sensitivity and exceptional reproducibility.