| Related studies have indicated that the meniscus has many role such as bufferstress, shock absorption, increased joint contact area to reduce local stress, stabling andlubricating joints, nutrition of articular cartilage etc. It is vital in maintaining kneefunction. Arnoczky et al proposed the three areas classification method about menisciblood supply in the1982, in which the injured white area will cause losing of the abilityto repair. However, The arthritis followed by cartilage damage after injury or resectionof meniscus may be relate with the changing about stress in the articular surface of thetibia, the studies of Seedholm BB and Walker PS et al have shown that the medialmeniscus have to withstand the stress of50%in medial compartment, lateral meniscuswill be bear70%of the stress in lateral compartment, and the stress can increase on thearticular cartilage350%even though20%of meniscectomy. In addition, Fairbanks et alfirstly noted that the injury or missing of menisci will produce a series of performancesuch as wear of articular surface and cartilage hyperplasia, causing or promoting thedevelopment of osteoarthritis, and it has been confirmed by the relevant research. So far,the meniscus allograft transplantation is a very promising treatment, and it has beenreported to correct tibiofemoral articular surface stress around domestic and abroad, andrelated basic and clinical research has been developing and improving gradually.Allograft menisci transplant is very limited of its source in the ethical and legal,especially the disinfection methods and storage technology recently cannot meet theclinical needs, and there are less relevant reports around domestic and abroad. Now, wewill observe the effects of different disinfection methods in rabbit model about allograftmenisci transplantation experiments to provide some reference for the relevant basicresearch and clinical applications, and the standardization and regulation of allograftmenisci transplantation. ObjectiveTo comparison the disinfecting effects of different disinfection methods for rabbitknee meniscus; To observe the effects of different disinfection methods for allograftmenisci transplantation and to find out the appropriate disinfection methods to guideclinical applications.MethodsTwenty-two white rabbits were selected from New Zealand (2.5±0.5Kg) andwere injected20ml air with a50ml syringe by ear vein, and eighty-five inside andoutside meniscus of bilateral knee obtained in the condition of sterilization after therabbit died. Then all of the specimens needed to be planted Staphylococcus aureus（SA）and randomly divided into five groups: the group of iodine, the group of Cobalt-60, thegroup of glutaraldehyde, the group of ethylene oxide, and the group of saline (controlgroup), seven specimens were selected randomly from each group for bacterialquantitative detection, and the remaining specimens were sterilized by iodine soak,Cobalt-60irradiation, glutaraldehyde solution, ethylene oxide fumigation, saline soak,and so on. Seven specimens were randomly selected in each group for bacterialquantitative detection again after completing the disinfection and the remaining threesamples for histological observation,then the number of SA will be recorded in eachgroup before and after disinfection of bacteria, Statistical analysis was performed afterdata collection being completed.Another thirteen white rabbits were selected from New Zealand (2.5±0.5Kg) andwere injected20ml air with a50ml syringe by ear vein, and fifty meniscus of bilateralknee obtained to preserve for one month at-40°deep frozen condition immediately afterlethal by air embolism. Then all of the specimens randomly divided into five groups: thegroup of iodine,the group of Cobalt-60, the group of glutaraldehyde, the group ofethylene oxide, and the group of saline (control group), each group of Specimens weresterilized to prepare for transplantation. Fifty Japanese rabbits were selected （2.5±0.5Kg）and were randomly divided into five groups: the group of iodine,thegroup of Cobalt-60, the group of glutaraldehyde, the group of ethylene oxide, and thegroup of saline (control group), the sterilized menisci from New Zealand rabbits weretransplanted into right leg knee of the Japanese rabbits respectively, the whole ofspecimens were removed in each group after6weeks, one of the seven specimenswere randomly selected for biomechanical testing, the remaining three specimens forhistological observation.ResultsQuantitative analysis showed that the bacteria are grown successfully in groups offive menisci specimens after inoculating SA for48hours, the average number of SA onspecimens rang from5.26x102to6.29x102, The group of povidone-iodine have thelargest number of bacteria, but the group of cobalt-60group have the least the numberof bacteria among these groups. The statistical results suggest that the difference twogroups among these groups is not statistically significan（tP>0.05）. Results of the fivetypes of disinfection methods display that group of cobalt-60, group of glutaraldehyde,group of iodine, group of ethylene oxide have the average number of less than1permenisci specimen about SA, group of sodium chloride have the average amount of415SA per menisci specimen. Sterilization rate of group of Cobalt-60, group of ethyleneoxide, group of glutaraldehyde, group of povidone-iodine is100%, but the group ofsodium chloride was only81.854%. The results of pathological examination showedthat there have a large number of nucleus in the organizational structure. The group ofpovidone-iodine have the most complete preservation in structure. In addition, group ofcobalt-60and group of glutaraldehyde have complete preservation in structure thatarranged relatively neat and rules except widely distributing smaller pores. The group ofsodium chloride have more serious damage in structural which arrange in a moretortuous and widely distributed a large number of larger pores. The group of Ethyleneoxide have the most serious damage in structural which arranged tortuous, disorganize,irregular and widely distributed a large number of large pores or even defects. The biomechanical test results after meniscus allograft transplanting for6weeksusing five different disinfection methods (load-bearing) show that the group ofPovidone-iodine were exposed to the maximum load by average of270N and the groupof Ethylene oxide were exposed to the minimal load by average of40N. Statisticalresults suggest that the group of povidone-iodine, the group of cobalt-60, the group ofglutaraldehyde and the group of sodium chloride group are greater the average loadwithstanding than the group of ethylene oxide, the difference among these groups wasstatistically significant（P<=0.01）. The average load of the group of povidone-iodine exposedgreater than the group of cobalt-60and the group of sodium chloride and the difference wasstatistically significant（P<=0.05）. The average load of the group of glutaraldehyde exposedgreater than the group of sodium chloride and the difference was statistically significant（P<=0.05）, there was no statistically significant difference between the other groups（P>0.05）.The results of pathological examination showed that varying degrees of damage in eachgroup menisci about organizational structure and a large number of cell infiltration fromoutside to inside can be seen compared with the previous transplantation. The group ofpovidone-iodine is the most complete in structure which neat and rules with somewidespread uniform fine pores and additional new tissue growth of receptor in few partsof these specimens. The group of Cobalt-60is relatively complete in structure which isarrange relatively rules with little tortuous and widely distributed uniformly smallerpores and additional new tissue growth of receptor in few parts of these specimens. Theof group glutaraldehyde seems relatively intact in structure which is arrange neatly andregularly except widely distributed uniformly smaller pores. The group of sodiumchloride have more serious structural damage which is arrange tortuous and irregularwith a large number of widely distributed large pores or even rupture and additionalnew tissue growth of receptor in few parts of these specimens. The group of ethyleneoxide is most serious damage in structure which have a large number of widelydistributed free broken tissue fragments with structural disorder and very irregular, evenlarge pores or severe tissue defects. ConclusionsThe disinfection methods of povidone-iodine, cobalt-60, glutaraldehyde andethylene oxide are able to effectively kill pathogenic microorganisms (SA) and toachieve clinical sterilization requirements allograft meniscus with maintaining a certaincompressive strength of allograft meniscus about the first three methods of four.Povidone-iodine is the best disinfection methods for preservation of allograft meniscusin structure among of these methods and have been showed the good biomechanicalproperties. Therefore, we suggest that povidone-iodine soaked disinfection methodsshould be recommend to sterilize tissue preservation of allograft menisci, butdisinfection by glutaraldehyde of allograft menisci have maximum compressive strengthand maybe provide another possible choice after being improved. Although thesterilizing effect is very good sterilized by ethylene oxide, allograft menisci structuraldamage is very serious with losing its compressive strength that required by clinicalapplication and it will unable to play due role of meniscus, so this kind of disinfectionmethod will not be recommended for sterilization and preservation of allograft meniscitissue. |
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