| Purpose1) By exploiting the physical property that there is no stress within bone harvest chamber ( BHC) , We investigates whether the orientation remodeling exists when there being no stress; 2) We implanted bone in bone harvest chamber to explore that bone matrix affects ingrowths in BHC.MethodThe bone harvest chamber (BHC) methodology is adopted in this study. Five female Japanese white rabbits, age 12 months, weight roughly four kilograms, non - conceived, and the epiphyses are ra-diographically confirmed closed, were used for the study. The rabbits were housed in rabbit cases and fed with the whole Rabbit chow and allowed unrestricted activity during the study. The bone harvest chamber is a cylindrical Ti implant body with a transverse 1 - mm wide canal for tissue ingrowths. Retrieval of the contents of the canal is allowed with minimal disturbance to the surrounding bone. Bone harvest chambers were implanted into the tibia under aseptic operation, left empty for two months so that getting integration with bone. Eightweeks after BHC had been implanted into the bone, we began to impose researching factor, that is, bone re - implantation and tissue retrieval every one month. The tissue that had been harvested, were fixed in 10% formaldehyde solution buffered by PH7. 4 PBS for 8 hours and decalcified in 20% EDTA solutions buffered by PH7.4 PBS for 1 month, then embedded in paraffin. Each rabbit was put into surgical procedure four times at four stages. At first operation, The BHCs were transplanted into each rabbits both side tibias and left for empty. At second operation, one iliac bone block was implanted in one side, and another side keeps empty. The tissue taken from the second and third stage was sliced into sections longitudinally, and we compare the amount of bone ingrowth in the implanted bone chamber with that of the empty. In fourth stage, both BHCs were left empty and the tissue were sliced into sections transversely. We compare the tissue harvested in empty BHCs in second and third stage (longitudinally sliced) with the tissue in fourth stage (transversely sliced) to proceed the direction analysis. Bone.ingrowth analysis; the area of bone ingrowth on each section as percentage of total area is uesd as statistics, the BHCs within the implanted bone as case group, while the empty BHC as control group. Using analysis of deviation to the cross design data, the difference value is the remaining when the area percentage of each BHCs in the third stage are subtracted from that in second stage regardless whether bone has been implanted in BHCs, such can expel the influence of two stages and different individual. Direction analysis ; the standard deviation of orientation of osteocyte nucleus in each section is used as statistics to analyze whether there is difference between longitudinal and transversel sections. The sections taken in statistics are from longitudinal ones of all empty BHCs in second andthird stage and transversal ones of harvesting tissue in fourth stage. We use T test with unequal deviation, examining level P =0.05.Result1) the amount of bone ingrowths in BHCs is more in non - implanted bone than in mplanted bone. The difference was significance.2) The angle of the length axial of nuclei is significantly greater in longitudinal section than in transverse section.Conclusion1) Under the no - stress circumstance of BHC, bone remodeling possesses directivity. Stress is not the direct leading signal about bone reconstitution. We presumed that the structure of BHC might be related to orientation remodeling, which suggested that the relationship between orientation and stress is mediated by blood vessel. The action of stress may be achieved by affecting vessel distribution in some orieta-tion.2) the study has shown that implanted bone matrix inhibits bone ingrowths in the bone harvest chamber model. Results suggested these cells in the bone segment probably repressed by bone matrix when bones are broken.
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