Research Of Ultramicrostructure And Mechanics Of Bone Tissue On Various Periods Of Preservation At Ultra-low Temperature

Objective: To study the effection of various periods ultra-low temperature on structure and mechanics performance of bone tissue,and provid fundamental theory for clinical homologus bone allograft.Methods: Adult tibias were adopted as research materials, flaps and segmentes at the same position of bone had been preserved in liquid nitrogen(-196℃) for 2,4,6,8,10,12 monthes with cryoprotector(15%DMSO) and a two-step freezing schedule that experimental samples were pretreated in freezing(-55℃) were adopted. Various periods samples were rapidly rewarmed with aqueous bath(40℃) before experiment,and observed with light microscope and electron microscope,mechanics of anti-crush and anti-fold were tested.Results: (1) Bone microstructure:The bone cells and central tunnel of Haversian system in 2,4 month refrigeration refrigeration groups were similar to control group; The bone cell number had been decreased and central tunnel had been enlarged or ascidially enlarged in some cases after 6 monthes refrigeration. Bone matrix of 2,4,6,8 month refrigeration groups kept normal, dropsy and coagulation necrosis in fragmentis or glassy degeneration were emerged after 10 month refrigeration group.(2) Bone ultramicrostructure:Bone cellular structure was normal in 2,4 month refrigeration groups;Bone cells pyknosis were emerged after 6 month refrigeration group, osteocollagenous fibers lined up in order in 2,4,6 month refrigeration groups, osteocollagenous fibers was unclear in 8 month refrigeration group.(3) Bone mechanics test: Strength ultirnate and elasticity mould volume of 6 month refrigeration group and compression rate of 10 month refrigeration group had statistical significance distinction when compared with control group(P<0.05),but ultirnate lotus torecord of each refrigeration group had no statistical significance distinction when compared with control group(P>0.05).Conclusion: (1) The structure of bone tissue preserved at ultra-low temperature had been progressively damaged and the mechanics performance had been failed accompanied with...