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Sophie Mottard M.D. Randomised study comparing CrCo whole blood ions in MoM 28 mm THA and MoM SRA VS Vendittoli PA, Lavigne M, Mottard S, Roy A.

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Presentation on theme: "Sophie Mottard M.D. Randomised study comparing CrCo whole blood ions in MoM 28 mm THA and MoM SRA VS Vendittoli PA, Lavigne M, Mottard S, Roy A."— Presentation transcript:

1 Sophie Mottard M.D. Randomised study comparing CrCo whole blood ions in MoM 28 mm THA and MoM SRA VS Vendittoli PA, Lavigne M, Mottard S, Roy A

2 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Early metal-on-metal bearings P. Wiles stainless steel prosthesis 1965 G.K. McKee CoCr prosthesis 1966 M.E. Müller CoCr prosthesis 1938

3 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Key Factors hard on hard success... Optimal materials Surface roughness Well ajusted clearance Precise manufacturing Design Cast alloy Wrought alloy

4 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Possible Advantages MoM Bearing Surfaces Improved durability; Wear-resistant components; Absence of polyethylene particules; No secondary periprosthetic osteolysis. Radiograph of Müller MOM at 33-year follow-up

5 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Metal ions productions Under perfect conditions; Wear Corrosion Gradual elimination of metal ions by the kidneys Osteolysis: rare or should not occur Concerns persist - Tissue necrosis - Cancer risk - Allergies / hypersensitivity

6 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Modern MoM implants Serum levels with 28 mm CoCr implants W. Brodner, JBJS introduction of Metasul ® Metal-on-Metal

7 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Clinical experience with MoM “Larger McKee-Farrar heads showed less volumetric wear than small diameter heads” “In Vivo wear of metal on metal prosthesis during two decades of use” McKellop, CORR Aug 1996

8 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Analysis of fluid film lubrication in artificial hip joint replacements PROC INSTN MECH ENGRS 1997;VOL 211 PART 2 : ( JIN, DOWSON, FISHER) “ LARGER RADIUS HEAD AT SAME RADIAL CLEARANCE LEADS TO AN INCREASE IN FLUID FILM THICKNESS ” JIN,DOWSON,FISHER

9 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Randomised study comparing whole blood metal ions in MoM 28 mm THA and MoM SRA

10 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Study hypothesis Larger head sizes of Mom SRA would produce more metallic ions in comparison to 28 mm MoM THA. Main objective — Compare metal chrome, cobalt and titanium blood ions between MoM 28mm THA and MoM SRA. Specific objectives — Corelate morphological or biomedical; factors (age, sex, weight, activity level) and metal ions levels; — Determine wear in period for the 2 groups; — Steady state whole blood metal ion level.

11 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Study population HMR patient years old waiting for THA by one of the hip surgeons and candidate for a THA or a SRA Exclusion criterias — One-stage bilateral THA; — Charnley class C patients; — Deep joint infection; — Drugs, alcool abuse, psychiatric illness; — Pregnancy; — Hip arthrodesis; — Neuromuscular disorder; — Renal insufficiency; — Known or suspected metal allergy; — Known or suspected osteopenia or osteoporosis of the hip.

12 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Implants: SRA DUROM, Zimmer Warsaw Head Wrought Co-28Cr-6Mo, 0.2% C Cemented 2 mm increments (head and cup ) Cup Wrought Co-28Cr-6Mo, 0.2% C Wall thickness = 4mm Non modular Ti plasma spray for ingrowth

13 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Implants : THA CLS stem (Spotorno), Zimmer Warsaw Wrought Titanium; Uncemented (grit blasted surface). Allofit cup, Zimmer Warsaw Macro textured wrought titanium; 2.9 mm thickness; Modular with poly sandwich CrCo metasul insert.

14 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Blood collection Whole Blood samples — Pre-op — 3 months — 6 months — 1 year — 2 years post-op 1. 5 ml Discard ml TKA H600PP - 20° C Conserve In case of lost or need for a second analysis Stir well Analysis to be done 2. 5 ml Teklab H600PP (conserve in the freezer [-20ºC]) Stir well Collect

15 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Ion Analysis Finnaigan MAT Element 1 High Resolution Sector Field Inductively Coupled Plasma Mass Spectrometer ( HR-SF-ICPMS). Blood samples — Digest blood with concentrated Nitric Acid; — Add concentrated Hydrogen Peroxide to further digest lipids; — Dilution with water and internal standard; — Introduced into the spectrometer; Practical Detection Limits — Titanium ug/L — Chromium ug/L — Cobalt ug/L London, Ontario Lab

16 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Power Analysis Chromium Minimal difference to be detected= 1 ug/L Standard deviation in resurfacing= 1.03 * Alpha error of 5% (bilateral) Power 85% N=20 per group Estimated loss to follow-up 15% Required subjects N= 50 patients. (25 per group) * Jacobs JJ, Clin Orthop 1996

17 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Study population N=85THASRA SexeWomen 18 Men Age (years)5248 Surgery4243 Head size (mm) 28 (All) 49 (avg) BMI Kg/m 2 (mean) 28,6726,86

18 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Factors taken under consideration Sex; Smoking; Comorbidities; Blood sampling in the two weeks prior; Work exposure to metal; Work exposure radioactive substances; Other metallic implants; Medication; Naturals products; Activity level UCLA score; Cup inclinaison.

19 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Results Mean Chrome blood levels THA vs SRA Blood chrome (µg/L) ,10 1,06 1,69 2,23 1,60 1,76 1,65 2,35

20 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Results Median chrome blood levels THA vs SRA Blood chrome (µg/L) ,90 0,85 1,50 2,00 1,401,45 1,65 1,90

21 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Mean chrome, 1 standard deviation

22 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Results Mean Cobalt blood levels THA vs SRA Blood cobalt (µg/L) ,15 0,12 0,76 1,00 0,81 0,80 0,780,77

23 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Results Median cobalt blood levels THA vs SRA Blood cobalt (µg/L) ,12 0,11 0,74 0,96 0,73 0,78 0,73 0,54

24 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Mean cobalt, 1 standard deviation

25 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Results Sex; Smoking; Comorbidities; Blood sampling in the two weeks prior; Work exposure to metal; Work exposure radioactive substances; Other metallic implants; Medication; Naturals products; Activity level UCLA score; Cup inclinaison. No statistically significant correlation

26 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. THA 28 mm Cr (  g/l) Co (  g/l) Our Results, Metasul (1 y) 1,65 0,78 Brodner, Metasul (5 y)0.70 Jacobs, Mckee-Farrar (20-27 y)1,230,90 McDonald, Biomet M 2 a ( y) low/high carbon 3.74 SRA Our Results, Durom (1y)2,350,77 Jacobs, various SRA 3.862,80 Discussion

27 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Discussion Short wear in period; Stable ion concentration levels by 6 months; Both implants with the same MoM technology; — Metallurgy — Wrought CrCo — High carbon content (0.2%) — Tribology — Clearance — Sphericity — Surface roughness Metasul ® Metal-on-Metal Over 18 years of clinical experience and 250,000 implantations worldwide.

28 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. From the Theory (Jin and Fisher) Small heads Large heads head size } film fluid thickness Wear

29 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Discussion 2 Hypothesis: Corrosion Larger exposed surface increases ions in SRA In vivo = various lubrification modes — Fluid film — Bondary Cr ,35 Co 0,78 0,77 ug/L Both factor together might create similar amount ? Similar CrCo levels

30 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Conclusions Large and 28 mm diameters Metasul articulations produce similar metal ions during the first year of implantation. CrCo metal ions levels obtained could be consider safe from historical results obtained with similar levels.

31 Blood ions in metal-on-metal bearing surfaces Sophie Mottard M.D. Acknowledgments Daniel Lusignan, Research nurse Stéphanie Lapointe, Research assistant Zimmer, Warsaw for financial support


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