Metal Ion Release after Metal-on-Metal Hips, can it be prevented?

LARGE HEAD METAL-ON-METAL ARTICULATION ADVANTAGES | WORRIES | SOLUTIONS

“It would be a pity if the design failures of others would jeopardize the idea of large headed metal-on-metal hip

arthroplasty, and we would have to go back to the known disadvantages of metal-on-polyethylene bearings“

Ceramic Surface Engineering The ACCIS® system consists of CrCoMO components whose surfaces have been engineered with the ceramic Titanium-Niobium-Nitride (TiNbN) by physical vapor deposition (PVD) in order to minimize metal particulate wear and to pre-vent corrosion, thus preventing metal ion release. Better initial cup stability Press fit fixation by equatorial over-sizing in cups with a three radial design (fig d) is enhanced by compression forces only. It provides better and more reliable primary fixation than a pure spherical configuration as seen in many current designs . Reduced Wear Pre-clincial testing has shown a dramatic reduction in wear of the ACCIS® articu-lations over non-ceramic engineered articulations. Retrievals 6-10 years post-operatively confirm the patency of the applied technique. Pathological examina-tion of the biopsies of the synovium, taken during the revision demonstrated the complete absence of any adverse reactions: no signs of hyper-sensitivity and no signs of inflammation. (9)

Reduced Metal Ion ReleaseA clinical multi-centre follow-up study was done on 200 ACCIS®Resurfacing implants, Blood samples of 60 randomly selected patients were analysed before, immediately after surgery and at intervals of 3, 6, 12 and 24 months post-op . None of the patients at any point has shown any increase of cobalt and chrome ions in the blood and none of the blood ion levels has been over the normal values. (9) Diagrams comparing the clincial ion measurements after surfaced engineered resurfacing hips with non-coated implants are shown on page 4 .

not even in steep positions or smaller sizes Analysis of a group of patients within the study, with less than optimal condi-tions (abduction < 400 or > 500 , anteverted placements and small sizes, sug-gests that the ACCIS® principle protects also against the worst conditions: no increase in metal ions and no occurence of ALVAL were reported. (10)

“ Novel techniques for surface treatment and deposition can be used to modify the surface of the implant to protect the implant from degrada-

tion and corrosion, to improve the surface structure or chemistry.... or to increase wear resistance and to control friction at the interfaces .”. Reijo Lappalainen, PhD and Seppo S. Santavirta MD, PhD: CORR 2005 No 430, pp. 72–79

The Solutions

Literature(1) Crowningshield R: “Biomechanics of

Large Femoral Heads” CORR 1994 Vol

429 pp 102-107

(2) Beaulé, Schmalzried, Amstutz :

” Jumbo Femoral Head for the

Treatment of Recurrent Dislocations”

JBJS 2002 Vol 84A pp 256-264

(3) Thomas Smith Metal on Metal Total

Hip Arthroplasty with Large Heads may

Prevent Early Dislocation CORR 2005

Vol 441 pp 137-143.pdf

(4) Saffatato Toni:”Large Diameter

Bearings Reduce Wear in M-on-M Hip

Implants” CORR 2006 vol 456 pp 153-

158.pdf

(5) Australian Orthopaedic Register

Yearbook 2008. Available at www.dmac.

adelaide.edu.au/aoanjrr

(6) Visuri -- Reduced Cancer Risk in

Patients who Received a THA or TKA

Acta Orrth 2003 Vol 74 No 3 pp 351-360

(7) De Smet K: ”Metal Ion Measurement

as a Diagnostic Tool in Problems in

M-on-M Resurfacing” JBJS 2009 Vol.

90S pp 202-208.

(8) Pandit - Pseudotumours associated

with M-on-M Resurfacing JBJS 2008 Vol

90B pp 847

(9) Hamelynck K.J. : ” Ceramic

Engineered M-o-M Hip System for THA

and RHA. White paper November 2009.

rat sed

(10) Patil S, Woodnutt D, :”” MISHR-

Metal Ion Study in Hip Resurfacing “.

Presented at the EFORT Meeting in

Vienna 2009

(11) [ 21 ] Witzleb -Günther:” Exposure

to Cr Co and Mo from M-on-M THR and

HRA - Act Orth 2006 Vol 77 No 5 pp

697-705

Higher Joint Stability Large diameter components provide enhanced stability.(1) The larger jump distance (fig a) reduces the chance of dislocation. This the reason why large femoral heads are also used to treat recurrent dislocation. (2)

Better Range of MotionHip prostheses with large femoral heads provide the hip with a better range of motion (fig b) without the risk of dislocation.(3)

Less wear Large diameter metal-on-metal com-ponents has proven reduced wear characteristics.(4)

Resurfacing Possible As polyethylene requires a minimal thickness, it is not suited for the man-ufacturing of thin shells. Metal-on-Metal articulation is, till now, the only bearing surface that allows for hip resurfacing.

Early Component FailuresThe Australian Hip Register has annu-aly, since 2006, reported higher-than-expected revision rates in some of the metal-on-metal total hips and resur-facing hips. The reported early failure may be attributed to lack of primary fixation (5)

metal ion release Although the literature may not be conclusive,(6) the mere presence of un-physiologically high serum lev-els of cobalt and chromium in the blood of patients after metal-on-metal hip arthroplasty remains a matter of concern. Extreme levels of more than 50 µg/L of Cobalt or Chromium have been reported, main-ly in smaller size implants and in less than optimal angles of abduction. (7)

local reactions: ALVAL Originally named “pseudo-tumors” now known under the acronym, ALVAL, are tumor-like proliferations of soft tissues around the hip, It is believed to be a dose related, local reaction on the metal wear debris. It is especially seen in smaller size implants and in acetabular compo-nents placed in a steep position. (8)

Advanced Ceramic Coated Implant System

Advantages Worries

Cemented Large Head Cementless Large Head Hybrid Resurfacing Total Hip arthroplasty Total Hip Arthtoplasty Arthroplasty

(a)

(b)

(c)

(d)

manufactured and distributed by implantcast GmbH Lüneburger Schanze 26 D-21614 Buxtehude Germany Phone:+ 49-4161 744 100 E-mail: [email protected] www.implantcast.de

ACCIS ®

ACCIS® is a concept of Accis BV and implantcast GmbH and is

protected by international patents.Further information at:

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• http://www.implantcast.de

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metal ion study A clinical multi-centre follow-up study on 200 ACCIS® Resurfacing implants (Morriston Hospital, Swansea, UK: David J Woodnutt, MD, FRCS, FRCS (Orth); Neville Hall Hospital, Abergevanny, UK: Robin Rice, MD,BMBS,FRCS; Arthro Clinic Hamburg: Genio Bongaerts, MD) is performed. Blood samples of 60 patients are analysed before, immediately after surgery and at intervals of 3, 6, 12 and 24 monts after surgery. The data were compared to those published by Witzleb (11). Metal ion analysis in both studies were performed under the same parameters in the same laboratory.

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