| Objective:Fracture is the sudden structural break arose by the unevendistribution of stress and function when the internal stress caused by loadingexceeds ultimate strength. Biomechanics is the biophysics branch to studymechanical problem of biosome with mechanics principle and methods. Atpresent, the foreign scholars often use the pouous plateswith locking bicortical screws as rib internal fixation material applied inclinical treatment. Plate internal fixation is widely believed as the idealtreatment method to multiple fractured ribs, Home and abroad scholars believethat the effect of such plate internal fixation stand the comparison and the testof time. It is the gold standard for treatment. Judet Strut has goodhistocompatibility、strong plasticity and quick operation. The study adoptspouous plates with locking bicortical screws and Judet Strut to fixed the ribfracture model, measures the biomechanics related data of such two kinds ofrib fracture internal fixations through biomechanics experiment equipment,and analyzes the related indexes of the two kinds of internal fixations from abiomechanical perspective, so as to explores the advantages and disadvantagesof two internal fixations, provide exact scientific basis for clinical surgicaltreatment of rib fractures, and make clinical evaluation.Method: Get50fresh and frozen pork ribs, a total of25pairs. Theselected ribs shall come from male adult pigs, all muscles on the ribs shall berejected, and all these ribs shall not be relevant with trauma or tumor. Selectedspecimens must be similar to5~8human rib shape in the morphology (width,thickness) and exclude the deformity, trauma and obvious degeneration.25paires of parallel ribs were randomly divided into5groups. Each groupcontains5parallel ribs. Use the oscillating saw to artificially make fracture tothe rib body of the ribs (here referring to multiple fracture sites). Fixation ribs in each group of parallel ribs by usingstandard anterior plates with locking bicortical screws and fix another one byJudet Strut.5groups of ribs respectively divided into non-destructivethree-point bending tests、non-destructive torsion tests、destructive bendingtests、destructive reverse test and fatigue tests.Results:1In the non-destructive three-point bending test, standard anterior plat-es with locking bicortical screws group and Judet Strut group producedifferent average pressures in the case of different force displacement. Thestandard anterior plates with locking bicortical screws group was significantlyhigher than Judet Strut group. All Displacement P <0.05, this is statisticallysignificant. Standard anterior plate will have less deformation along with thebending of ribs under the action of external force. However, Judet Strut canbend synchronously with ribs within certain range. It has good toughness andcan maintain the displacement of the broken ends of fractured bone withincertain range. The yield strength of both of these two internal fixations arelarger than the force required for rib fracture and both of these two internalfixations can provide safety guarantee for clinical use.2In the non-destructive torsion test, the twisting force between thestandard anterior plates with locking bicortical screws group and Judet Strutgroup is different in different twist angles. Only when the twist angle is10°,the average torsional force of the standard anterior plates with lock-ing bicortical screws group is higher than that of Judet Strut group, while thereare no significant differences in the torsional forces in the case of the othertorsion angles. The result is statistically significant. And twisting force has nodifference when the twist angle is20°,30°or40°. It is found that, whenapplying constant twisting force, the ribs fixed with standard anterior plate allfractured longitudinally at the screw hole. However, the ribs fixed with JudetStrut are just deformed and dropped off, which has no secondary injury to ribs.So the screws of standard anterior plate themselves are traumatic to ribs. 3In the devastating three-point bending test and the destructive torsiontest, the bending resistance of the standard anterior plates with locking bicorti-cal screws group is much better than that of Judet Strut group. The maximumbending resistance of the standard anterior plates with locking bicor-tical screws group is231.52N,while the maximum bending resistance of JudetStrut is124.36N. And in the destructive torsion test, the standard ant-erior plates with locking bicorti-cal screws has no obvious advantage,compared with Judet Strut.4In the fatigue test, the initial stiffness and the final stiffness andstiffness between the Pouous Plates with locking bicortical screws group haveno statistical differences but their stiffness values change statistically. WhetherJudet Strut group or the Pouous Plates with locking bicortical screws group,after the fatigue test, their stiffness values are lower and reaches statisticaldifferences.The stiffness in Pouous Plates with locking bicortical screws groupare greater than those of Judet Strut group decline after long-time fatigue test,and have statistical difference. The decreasing degrees of the stiffness in thePouous Plates with locking bicortical screws group are greater than those ofJudet Strut group.Conclusion：1The anti-bending performance of the Pouous Plates with loc-king bicortical screws is superior to that of Judet Strut. And both are reliablefixation materials of rib fractures.2The anti-torsion properties of the standard anterior plates are betterthan that of Judet Strut when the twist angle is less than10°. And when twistangle is larger than10°, the anti-torsion properties of the Pouous Plates arenot significantly better than those of Judet Strut. What’s more, the screw itselfis a kind of injury to ribs.3Judet Strut prevails in the anti-fatigue force performance.4Compared with Pouous Plates, Judet Strut is easier, faster andtime-saving in surgical operation. It does not deed bone drill which reduces blooding in operation, is stable and reliable for reduction of fracture, and doesnot need to be taken out generally. |
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