| Interlocking intramedullary nailing has been accepted as an established technique for several decades. Depending on the excellent biomechanical properties, the technique is an important method in the fixation of fracture. However, the difficult of operating process and the demand for radio-equipment restrict the ' development of intramedullary nailing. At present, the study about material, biomechanics, frame-Contrivance, and instruments has been performed deeply. With the deeper cognized about biomechanics and intramedullary morphology, the interlocking intramedullary nailing has matured on rise, and the development of self-locking nailing brought an important chance for it. After the review about the intramedullary morphology completely, a new type SLN, Bevel-SLN, has been designed as the philosophy of self-locking in the intramedullary. It was shown that the prototype Contrivances represents satisfying mechanical properties, and this new development may be of particular interest for clinics as a convenient and applied method of fracture fixation.The intramedullary morphologic study of Chinese femur and tibia has been performed completely and deeply, but, the data of Chinese humerus intramedullary morphologic study was defected until my study. So it is the first step in my experience to measure the humerus morphology for the completing the intramedullarymorphology and for the contriving about SLN. 1. Measurement of Intramedullary Cavity:Object: Through the measure about intramedullary cavities castings of humerus, we acquire the data of native for developing the inter-locking nail. Method: There are four groups in the experiment. In the first to third group which is divided by the material: wet bone, fresh bone and dry bone, we measure the intramedullary cavities castings which were cast by activated dental resin; in the fourth group, we measure the intramedullary cavity about humerus of the volunteers by helix CT. All of the data has been put into the SPSS for observing the relation among the four groups. Result: It is nearly an irregular cylinder at the upper 2/3 of humeral medullar, but there is a forth angle with 8. 82 + 0. 27 degree at the under 1/3 of the humeral medullar in sagittal plane. The thickest compact bone lies in the groove for radial nerve, near6 mm in average. The most narrow part of the intramedullary cavity is located in the under 1/3 of humerus, and its diameter is from7 mm to 8 mm in the sagittal and corona plane. It has been proved by statistic data that there is no difference between the wet bone and fresh bone group, but there is a remarkable difference between the dry bone and others' group. The data of CT group is near to the wet bone and fresh bone group at most plane, and more different than the dry bone. Conclusion: the morphologic shape of humerus is similar to an irregular cylinder. The wet bone is an ideal material in the intramedullary morphologic study.2. Contrivance of Self-locking nail with BevelsObject: A new interlocking system has been developed which is easy to use, carries out an aligning on the distal fracture fragment and stabile fixation, reduces the exposure to radiation for the surgeon and the patient, and allows for a decrease in operating time. Method: the new interlocking system is a Self-locking nail with Bevels; including in-nail, out-nail and across-nail, the designproperties of frame: basing on the bevel-principle, the axial force is turned into across-force, which is completed the intention of controlling the across-nail' s movement by the trail' s movement . there are ten dry-bone simples which has been made as the fracture model of the middle-femur to test the handling of prototype nail and the shearing force, and showing the retention in intramedullary cavity by the radiogram. Result: frame of prototype nail has performed the movement as design; the process is stable and reliable; it is satisfied on the retention of intramedullary cavity; the shearing force between the across-nail and main-interface is enough to cut anythi...
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