The Biomechanical Study About The Treatment Of Femoral Head Avascular Necrosis With Interior Supporting System And Tantalum Rod

Objective：To compare the biomechanics research with interior supporting system andtantalum rods in simulating treatment of avascular necrosis and provide a new methodfor the treatment of femoral head avascular necrosisMethod：①Grouping and Modeling: The comparative analysis is based on biomechanicaltesting on15normal adult femoral specimens, which are randomly dividedinto three groups: Group A, the normal group; Group B, the interior supportingsystem group, i.e., along the center of the femur neck below the lateralfemoral trochanter to0.5cm at the femoral head cartilage, a1cm (in diameter)tunnel is drilled, a space of2cm(in diameter) is scraped with a curette at thefemoral head cartilage to install the interior supporting system, bone graft in it;Group C, the tantalum rod group, i.e., a tunnel of the femoral head and neck iscreated based on Group B, and the space under the femoral head cartilage isexpanded to graft bone and install the tantalum rod.②Mechanic testing: Materal Test System machine is adopted to gradually loadaxial torque to the top of femoral heads until the latter is damaged, record andcompare the strain of fossa trochanterica, femoral calcar and subtrochantarer,and the maximum load of the femur when its head is sunk and its neck isdamaged. SPSS18.0statistical package is used to analyze the data andpairwise T-test is employed to make a comparison within groups, test level α=0.05. Result：①When the load is300N, the strains of fossa trochanterica, femoral calcarand subtrochantarer within Group A are respectively100.27±10.05、368.86±30.00、123.23±12.15, within Group B,106.41±10.20、428.62±40.30、150.25±15.10, and within Group C,181.97±17.71、365.84±35.10、135.62±13.2；as for the strain of fossa trochanterica, GroupC＞Group A and Group B (P＜0.05). According to the above numbers,we can see that there is no significant difference between Group A andGroup B under300N loading condition (P＞0.05). while there is greatdifference between Group A and Group C (P＜0.05), and between GroupB and Group C(P＜0.05). As for the strain of fossa femoral calcar andsubtrochantarer, there is no any significant difference among the threegroups (P>005). As for the strain within groups, the strain of group A ismainly gathered in the calcar, significantly higher than that of fossatrochanterica and subtrochantarer (P <0.001), although the strain ofsubtrochantarer is higher than that of fossa trochanterica, but the differencesbetween them are not significant (P>0.05); The strain of Group B can beordered as femoral calcar, subtrochantarer and fossa trochanterica, thedifferences among the three parts are great (P <0.001); The strain of GroupC can be ordered as femoral calcar, fossa trochanterica and subtrochantarerfrom largest to smallest and their differences are satistically significant (P<0.05).②When the femoral head is sunk, the maximum load of group A is1783.44±209.62, that of group B is3907.50±396.60, and that of group C is2873.77±319.70. Obviously, the maximum load of group B is greater than that ofgroup A and group C (P <005); When the femur is damaged, the maximumload of group A, group B and group C are respectively6536.74±593.19,5648.19±479.04,5411.99±503.06, the differences among the load of thethree groups are not significant (P>0.05). These results indicate that the strain of femoral head is mainly gathered in the calcar once the femoral headis pressed under normal circumstances. After interior supporting systemimplantation, bone graft and tantalum rod implantation, bone graft,although strain had change but it was still mainly concentrated in the calcar,and the load of collapse of femoral head and femoral damage is higher andapproach to normal.Conclusion：①After implanting of interior supporting system and tantalum rod withbone graft, the stress distribution and strain and bearing load offemoral head and neck being pressured are approach to normal.②The role of interior supporting system implantation with bone graftagainst collapse of femoral head is superior to that of tantalum rodimplantation with bone graft.