Abstract:

BACKGROUND: For reducing the stress shielding, a lot of the schemes have adopted, and there is no great improvement although via the trial and the application for several ten years. It comes from a root which is the combination by thigh bone (abbreviation of the bone) and metallic handle (abbreviation of the handle) which causes the serious problems of absorption of bone quality, and this kind of stress shielding effect is produced by abnormal stress and abnormal strain, and affected by various factors, so there is no effective and applicable method to solve this problem.   
OBJECTIVE: To select the primary porous layer scheme as the subject of the study and entirely change the appearance and inherent quality as the metallic handle that cannot transmit the stress is the key to eliminate the stress shielding; making the senior porous layer with the effective measure is the basis to eliminate stress shedding and can solve the disaster and partial inferior position aroused by the primary porous layer.
METHODS: The cobalt-chromium-molybdenum alloy small metallic spherules with equal diameter were used to manufacture the senior porous layer structure. The structural member employed in the thigh bone could separate the handle from the bone. This structural member welded on the plane of bone neck could fix the handle with  calcar osteotomy surface. And these structural members had an ability to eliminate all the stress shieldings on the artificial hip joint surface.
RESULTS AND CONCLUSION: The senior porous layer was made with cobalt-chromium-molybdenum alloy small metallic spherules with the same diameter (1.00-1.29 mm), and the surface of the porous layer was plated with high property of medium layer alloy and arranged orderly and inseparable, and then connected with active diffusion welding technology. The diameter of all the holes was 155-200 μm and distributed evenly which was benefit for the bone unit to grew. The alloying of metal materials, ceramic of alloy surface and controlling of size and number of wear particles can solve the bone dissolution of the surrounding porous layer of bone, metal dissolution as well as its pure cobalt and chromium particle toxicity, cancerization and leukemia. A stipulation of theoretical basis was to eliminate the handle rigidity firstly that could made the separation of handle from the bone became the premise for eliminating the stress shielding. The calcar osteotomy surface grew into the pores of the structural member welded on plane of bone neck could fix the handle, and that was the basis for eliminating the stress shielding. The common roles can eliminate the stress shielding in thigh bone, and the stress shielding on acetabulum is easily to eliminate.

Key words:  joint prosthesis, hip joint, femur, stress, mechanical