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CLINICAL UPDATE

QMoM resurfacing post-op.

QMoM THR post-op.

GP notes

Revise if: progressive bone or soft tissue loss, or solid pseudotumour, even if BTZNQUPNBUJD JPOTVTVBMMZSBJTFE HSPJO pain and high ions or rising ions over threshold. Watch if: asymptomatic/minor discomfort BOEOPSNBMJPOT OPQTFVEPUVNPVST asymptomatic/minor discomfort and raised TUBCMFJPOMFWFMT SFWJFXXJUIYSBZBOEJPOT BUTJYNPOUIT  Surgical problems: solid pseudotumours OFFEUPCFFYDJTFEBTUIFZSFDVSBOEBSF associated with a poorer outcome – they DBOCFEJTUBOUUPUIFVTVBMPQFSBUJWFTJUF BMXBZTTVTQFDUJOGFDUJPODBOPGUFOMFBWF UIFTUFNXJUI5)3SFWJTJPOTBCEVDUPSTBSF

"MM.P.5)3BOESFTVSGBDJOHT need post-op follow-up clinically, biochemically (cobalt and chrome levels) BOESBEJPMPHJDBMMZ FWFOJGBTZNQUPNBUJD conventional size heads (28-32mm) at routine intervals, larger heads and resurfacing more often. Refer when indicated (see chart).

Orthopaedic surgeon notes "MMSFGFSSFEQBUJFOUTTIPVMECFDMJOJDBMMZ  biochemically and radiologically assessed. 'Normal' causes of failure need to be DPOTJEFSFE FHJOGFDUJPO "TBNJOJNVN  artifact reduction MRI or CT should be performed.

often badly damaged and may need repair at revision (or later once the biology has TFUUMFE NBZOFFEDPOTUSBJOFEJNQMBOUTJG TFWFSFNVTDMFEBNBHFVTFDFSBNJDIFBEJG macroscopic metal particles present. Ref: www.tga.gov.au/hp/information-devicesmom-hip-implants.htm O

The Hip Prosthesis Story %VSJOHUIFTJYZFBSTUIF"VTUSBMJBO EFTJHOFE%F1VZ"43IJQQSPTUIFTJTXBT on the market here, it was used in about QBUJFOUT DPOWFOUJPOBM"43 BOESFTVSGBDJOH"43 %BUBGSPNUIF National Joint Replacement Register show that of about 197,000 conventional total hip replacements during 1999-2010, about 21,400 were metal-on-metal (MoM), as were about 14,000 resurfacing implants. The DePuy prosthesis has been recalled but other MoM prostheses are now in the spotlight. The New York Times last year reported UIBU%F1VZhTQBSFOUDPNQBOZ+PIOTPO Johnson had not been quick enough to acknowledge and respond to high failure SBUFTSFQPSUFEJO"VTUSBMJB*OGBDU JO FBSMZUIF'%"IBEHJWFOIJHISBUFTPG SFWJTJPOBTUIFSFBTPOXIZ64"BQQSPWBM was not forthcoming. The newspaper suggested that DePuy's actions might undercut its defence of related lawsuits. 'VMMQSPTUIFTJTSFDBMMIBQQFOFEJO"VTUSBMJB in December 2009 and worldwide in "VHVTU Patients suing the company claim that metal debris from the hips, made from a cobalt and chromium alloy, causes tissue death around the joint. This type of local reaction can cause premature failure of MoM hip implants, and increase the risk of complications with revision surgery. There is also concern that chromium and cobalt ions from a wearing MoM implant can enter the bloodstream to harmful levels. medicalforum

In 2011, an article in the MJA suggested the DePuy product recall was likely to DSFBUFVODFSUBJOUZBOEBOYJFUZJOUIF QBUJFOUTVOEFSHPJOHIJQSFQMBDFNFOU FBDIZFBSJO"VTUSBMJB1SPCMFNTXJUI the prosthesis had been reported by the "VTUSBMJBO0SUIPQBFEJD"TTPDJBUJPOJO oUIF"43SFTVSGBDJOHQSPTUIFTJTIBEB revision rate greater than twice the rate for all other resurfacing prostheses combined. *OBOECPUIUIF"43SFTVSGBDJOH and conventional prostheses were reported in the same light. The MJA article said that at 6 years, the "43DPOWFOUJPOBMQSPTUIFTJTIBEB BOEUIF"43SFTVSGBDJOHQSPTUIFTJTBO 11.1% cumulative percentage revision rate. )PXNBOZQBUJFOUTXJUIBO"43QSPTUIFTJT will eventually require revision remains unknown but is potentially high. "OPUIFSBSUJDMFJOUIFTBNFJTTVFPGUIF MJASFQPSUFEQBUJFOUTXJUI"43QSPTUIFTFT

FACTS: MoM Hip Prostheses t %F1VZhT.P."43IJQQSPTUIFTFT XFSFSFDBMMFEJO%FDFNCFS t "SPVOE8"QBUJFOUTIBWF UIFTFJNQMBOUTBOEBSFFOUJUMFEUP DPNQFOTBUJPO t "CPVUTFWFOUJNFTBTNBOZ.P. QSPTUIFTFTIBWFCFFOJNQMBOUFEBOE OFFEPOHPJOHBTTFTTNFOU t 1BUJFOUTXJUI.P.QSPTUIFTFTNBZ HFUMPDBMBOETZTUFNJDFGGFDUTGSPN SFMFBTFEDPCBMUBOEDISPNBUFJPOT

who seemed to show an association between high serum metal ion levels and systemic UPYJDJUZ5IFUISFTIPMEPGTJHOJGJDBOUCMPPE levels is unknown and needs researching. With varying innate susceptibility amongst patients, other MoM hip prostheses that are not performing well are now a concern. *O"VTUSBMJB %F1VZIBWFFOHBHFE $SBXGPSE$PNQBOZ "VTUSBMJB 1UZ-UE UPSFJNCVSTFGPSFYQFOTFTBTTPDJBUFEXJUI UIFSFDBMMPGUIF%F1VZ"43QSPTUIFTFT 0VUPGQPDLFUFYQFOTFT MPTUFBSOJOHTBOE medical costs are covered for registered patients and if they seek compensation for pain and suffering and undergo revision TVSHFSZ UIFSFJTUIF%F1VZ"431BUJFOU Compensation Programme that bypasses the Court system. 'JOBMMZ UIF5("IBTSFDMBTTJGJFEBMMIJQ  knee and shoulder prostheses from class IIb (medium risk) to class III (high risk) medical devices and from 1 July 2012 premarket assessment for any future devices will increase. O

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Medical Forum WA 3/13  
Medical Forum WA 3/13  

WA's Independent Monthly for Health Professionals