9 dec 3 sterilization implants

8/6/2019 9 Dec 3 Sterilization Implants

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Sterilization of ImplantsBiomaterials Science:An Introduction to Materials inMedicine; Ratner, B.D.;Hoffman,A.S.;Schoen, F.J.;Lemmons, J.E.; Eds.; 1996,Academic Press: USAISBN: 0-12-582460-2pp. 415420


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C H A P T E R

Implants and DevicesJAMBS M. NDERSON,BRYANEVACQUA,A. NORMANIUNIN,LINDAM. GW, ALM S. H o ~ ,~ ~ C H A E LLEIN, JOHN B. KOWALSKI,ROBERTF. MORRISSEY,TEPHENA. OBSTBAUM,UDDY D.R~TNWFREDERICK. SCHQEN, SJRAWN, A m DIANAWHIITLESEY

9.1 ~ T R O D U C I ~ O Nbacteria, yeasts, molds, andviru9cs. The p- of even m e

Rdm i c k 1.Schaan bacterium on an implant rtnders it n o n d e . St&v sbotddnot be confused with dtanlintos. A shiny stainless~ e duhctrhup,em dnrribD bionutoials m y s d y b.nonstdlc ( m n h e t dwith n u -td medical dcviccs. T b e areas & o m illustrate microorganisms),while a rusty nail will bes t d eahtrexpsore

an d medical considtrations and tv an appropriate sterilization m d d . m scalmateda nbe ~~~~d sterile,How then is sterility measured or p m d ?For relatiwlysmall numbers of mplants lassuming the implant is notl a r p to t a r in its entirev), d r y an b* pimmersing the item into liquid m i m b i o l o g i d dnuc media.area hasirs own uniqueprobIems Lf it is sterile, no rnigobial growth will be h e w e d ; if it isnonsteriie, the culture mcdium will k m c urbid M a d tof microbid (Fig. I) . T&g small numbers ofsamples, however, dm not giw very meaningful informationabout the sterility of a large batch of implane that havesubjecled to an industrial-scnlesterilization,n ~ t e r i k -

9.2 STERUINTION OF IMPLANTS tion validation smdia are used to determinewhat is d e d hesterility assurance lwel (SAL).fohn 8. Kowalski m ~ d obert F . Morrissey The SAL i s the probability that a given implant rffilldnonsttrile following exposure to a given sterilization p-ebody of a human or an animal n, accepd SAL, or im&ntss 10-6 orumt i~~feaionhat can lead ta a probnbil,F of no than one in donimplant --Ie.

The determination of a SAL with the enumerationrhe bioburdm, ofviable microo* onheimplant just prior ro sterilization(Morrisscy, 1981). BioburdtnisusuaUy dcternlinadon 10-30 samples and involveswashing,shaking, or sonicatingthe microorganismsoff tbeimplant into

a sterile m r y luid such as a saline solurion. By using an-ventional microbialogical technique, the number of mimoor-ganisms in the recovery fluid can bc determined.STEMUTY AS A CONCEPf Once the bioburden is known, mional-run smilizsrionstud~esa n be perfomad to dttyrnine the micmbisl rare of

*'Sterile" i s defined as the absence of all living organisms. kii1orprocess cthaliry. In a fractionalsterilizationrun, implantn i s cspeaally includes the realm of m i m ~ s o r s m s ,uch as samples (in packaga) are exposed ta a hadi on o f the desiradI **41 5 C n p y w r n Y W 6 b M h c * . b K .M n g b a o l r e p ~ l n h d


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IWIANT AND PACKAGING C O M P A ~ U T YThe first mnccrn when choosing a srcrilization

ture rangt of 52" to 5 X , he tests mustsarnpIcs exposed to a 570C p m . lso, the~teril~zat~onxposures rpwt be considered in

O V M V E W OF STEltlUZATlONMmfODSThe first sttrriizarion method to be used for implants wasautoclaving, which tnvolvss exposure to saturatedsteam underpressure. Owing to the relatively high teniperature of the pra-

ccss (121C),ast nonmetallgc inlplants and packaging materi-alscatlnotbc sterilizedby hism~thod.Th~simitation Ird to t h e n6.Z. Mimblr[ kltlc u r v t ~ J o n d l t a f m n dfncr irrn* lsdbdevelopment and useof thylene oxide (Fa)as and lorltzing rlon runs. Time w achaue a I O d a S A t is apprammatdy 1W m h

sterilizaa'mcycleordose. For example, if the p r o p p ~ d rocess. exposure t i m ~s 2 hr, the fractional nrns may have exposuret imuof 3 4 4 0 , md50 min. Sampla frotn theserunsare testedfor sterility and the results plotted to determine the ~xposuretime required to achieve a 10m6 AL. The resulrs froomouch astudy are shown in Fe 2. n thh example, the average biobur-den pet sample was 240. fter h e30-,4-, and SO-min frac-tional cycks, there were, rcspectiveiy, 28150. 7 /50 , aad 1/50samples tbatwere still rlofistwilt. ThecalcuIatcdtime to achievea 10-' SAL for r h s hypothdcal bioburdm and sterilizationpmecssisapproximately100min, which is within theproposed120-min -sun time. Note that when there i s less than onesurviving o r m s m per unit, therrh obviously not 0.01of norganism on each unit, for cxampk but a probability of 1 in100 thin rhc unit i s nonsterilc.


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9 dec 3 sterilization implants

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