Medical Forum WA 3/13

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CLINICAL UPDATE

Q MoM resurfacing post-op.

Q MoM THR post-op.

GP notes

Revise if: progressive bone or soft tissue loss, or solid pseudotumour, even if BTZNQUPNBUJD JPOT VTVBMMZ SBJTFE HSPJO pain and high ions or rising ions over threshold. Watch if: asymptomatic/minor discomfort BOE OPSNBM JPOT OP QTFVEPUVNPVST asymptomatic/minor discomfort and raised TUBCMF JPO MFWFMT SFWJFX XJUI Y SBZ BOE JPOT BU TJY NPOUIT Surgical problems: solid pseudotumours OFFE UP CF FYDJTFE BT UIFZ SFDVS BOE BSF associated with a poorer outcome – they DBO CF EJTUBOU UP UIF VTVBM PQFSBUJWF TJUF BMXBZT TVTQFDU JOGFDUJPO DBO PGUFO MFBWF UIF TUFN XJUI 5)3 SFWJTJPOT BCEVDUPST BSF

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

Orthopaedic surgeon notes "MM SFGFSSFE QBUJFOUT TIPVME CF DMJOJDBMMZ biochemically and radiologically assessed. 'Normal' causes of failure need to be DPOTJEFSFE F H JOGFDUJPO "T B NJOJNVN artifact reduction MRI or CT should be performed.

often badly damaged and may need repair at revision (or later once the biology has TFUUMFE NBZ OFFE DPOTUSBJOFE JNQMBOUT JG TFWFSF NVTDMF EBNBHF VTF DFSBNJD IFBE JG macroscopic metal particles present. Ref: www.tga.gov.au/hp/information-devicesmom-hip-implants.htm O

The Hip Prosthesis Story %VSJOH UIF TJY ZFBST UIF "VTUSBMJBO EFTJHOFE %F1VZ "43 IJQ QSPTUIFTJT XBT on the market here, it was used in about QBUJFOUT DPOWFOUJPOBM "43 BOE SFTVSGBDJOH "43 %BUB GSPN UIF 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 %F1VZhT QBSFOU DPNQBOZ +PIOTPO Johnson had not been quick enough to acknowledge and respond to high failure SBUFT SFQPSUFE JO "VTUSBMJB *O GBDU JO FBSMZ UIF '%" IBE HJWFO IJHI SBUFT PG SFWJTJPO BT UIF SFBTPO XIZ 64" BQQSPWBM was not forthcoming. The newspaper suggested that DePuy's actions might undercut its defence of related lawsuits. 'VMM QSPTUIFTJT SFDBMM IBQQFOFE JO "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 DSFBUF VODFSUBJOUZ BOE BOYJFUZ JO UIF QBUJFOUT VOEFSHPJOH IJQ SFQMBDFNFOU FBDI ZFBS JO "VTUSBMJB 1SPCMFNT XJUI the prosthesis had been reported by the "VTUSBMJBO 0SUIPQBFEJD "TTPDJBUJPO JO o UIF "43 SFTVSGBDJOH QSPTUIFTJT IBE B revision rate greater than twice the rate for all other resurfacing prostheses combined. *O BOE CPUI UIF "43 SFTVSGBDJOH and conventional prostheses were reported in the same light. The MJA article said that at 6 years, the "43 DPOWFOUJPOBM QSPTUIFTJT IBE B BOE UIF "43 SFTVSGBDJOH QSPTUIFTJT BO 11.1% cumulative percentage revision rate. )PX NBOZ QBUJFOUT XJUI BO "43 QSPTUIFTJT will eventually require revision remains unknown but is potentially high. "OPUIFS BSUJDMF JO UIF TBNF JTTVF PG UIF MJA SFQPSUFE QBUJFOUT XJUI "43 QSPTUIFTFT

FACTS: MoM Hip Prostheses t %F1VZhT .P. "43 IJQ QSPTUIFTFT XFSF SFDBMMFE JO %FDFNCFS t "SPVOE 8" QBUJFOUT IBWF UIFTF JNQMBOUT BOE BSF FOUJUMFE UP DPNQFOTBUJPO t "CPVU TFWFO UJNFT BT NBOZ .P. QSPTUIFTFT IBWF CFFO JNQMBOUFE BOE OFFE POHPJOH BTTFTTNFOU t 1BUJFOUT XJUI .P. QSPTUIFTFT NBZ HFU MPDBM BOE TZTUFNJD FGGFDUT GSPN SFMFBTFE DPCBMU BOE DISPNBUF JPOT

who seemed to show an association between high serum metal ion levels and systemic UPYJDJUZ 5IF UISFTIPME PG TJHOJGJDBOU CMPPE 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 %F1VZ IBWF FOHBHFE $SBXGPSE $PNQBOZ "VTUSBMJB 1UZ -UE UP SFJNCVSTF GPS FYQFOTFT BTTPDJBUFE XJUI UIF SFDBMM PG UIF %F1VZ "43 QSPTUIFTFT 0VU PG QPDLFU FYQFOTFT MPTU FBSOJOHT BOE medical costs are covered for registered patients and if they seek compensation for pain and suffering and undergo revision TVSHFSZ UIFSF JT UIF %F1VZ "43 1BUJFOU Compensation Programme that bypasses the Court system. 'JOBMMZ UIF 5(" IBT SFDMBTTJGJFE BMM IJQ 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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