Study Of The Actabular Component With Three-fins

Asceptic loosening of the component following THA is a common late complication. It is very difficult to treat actabular component loosening with bone defect. Reconstruction of actabulum is mainly relevant to design, selection and fixation of acetabular prosthesis and repair of deficient acetabulum. In early 1990's, General Hospital of PLA independently designed acetabular component with three-fins with intellectual property right. The three-fin actabular component has been used in revision surgery for 10 years and excellent result has been obtained. Compared with other components used for revision, the three-fin actabular component has its own distinct advantages. It can easily reach initial stability, bone restoration of hip rotation center and bone defect.Basic related research of the three-fin actabular component was done in this study. Initial stability of the three-fin actabular component implanted in actabulum in vitro with simulating bone defect was tested. Histology of three-fin acetabular component with moselized bone grafting to reconstruct deficient acetabulum was evaluated in dogs.1. Biomechanical study of three-fin actabular component in deficient acetabulumObjective: To assess the initial stability of three-fin actabular component implanted in actabulum with simulating bone defect in vitro.Materials and method: 1. Cyclic and continuous static axial load by MTS 858 Mini BionixII biomechanical test machine were respectively exerted on the three-fins actabular component in embalmed cadaver hemipelves to test the its resistance ability of pressure and torsion load. Under cyclic pressure or torsion load, Four factors with two levels that might influence component stability wereassembled into eight performing conditions by orthogonal design. Axial compression micromotion and torsion micromotion were collected under the eight working conditions. Under static compression or torsion load, the test was done on a selected performing condition most encountered in clinics.Resuls: After a hundred thousand cycles of compression loads, the performing condition of small bone defect,parallel of a fin with force line,press fit implantation and three fins acetabular component fixed with three screws demonstrated a lest micromotion equaling 83 to 96 um . If under the same performing condition, micormotions were less when fixation with screws than without screw, small bone defect length than big one, and press fit implantation than exact fit implantation, intersection of a fin with force line than parallel one. Under static compression load of 2058N, subsidence in screws fixation group was only 182 um less than that of without screw. 2. After a hundred thousand cycles of torsion loads, the torsion angle was 0.174?which was lest under performing condition of small bone defect, compression load of 686N, press fit implantation and three-fins component.If under the same performing condition, the torsion angle were less in small bone defect than that of big one, press fit implantation than exact fit implantation, compression load of 2058N than 686N, three-fins component than common component. Under torsion load, the breakdown torque in three-fin component was lOlNm, which was much higher than that of common component with screws.Conclusion: Under either cyclic loads or static load, the three-fin component has excellent axial stability and anti-torsion ability. The three-fin component is stable in deficient acetabulum and prevent overload from stressing on the bone graft, which is important for bone ingrowth.2. Study of three-fin acetabular component with morselized bone for restoration of deficient acetabulum in dogsObjective: To create acetabulum with bone defect model in dogs and study bone formation capability of morselized bone with three-fin componentMaterials and method: Three-fin component and common hemispheric acetabular component used for dog were made based on measurement of maximum diameter, depth and roof thickness of dog acetabular specimens. Acetabulums with bone defect were created in dogs...