1. Metal ions from orthopaedic implants : a cross-sectional study
Dr. Elmano A. Loures , MD
Dr. Daniel N. Loures , MD
Clarice N. Loures
Juiz de Fora,MG - Brazil
ILUSTRAÇÃO COMO FUNDO
Paper 36701

2. No conflicts of interest in this paper
Neither the authors nor any immediate family member has received anything of value
from or has stock or stock options held in a commercial company or institution related
directly or indirectly to the subject of this paper

3. Introduction 1988: Reintroduction of Metal-on-Metal bearings
Goals : to reduce wear and osteolysis
MOM devices implanted worldwide
Effects of elevated metal ion levels were always a concern – Cotogno & Holzwarth,2012
2009: 3º generation of MOM prosthesis and LDH
Reports of adverse reactions to metal debris
Indications drastically reduced
Some products recall or withdraw from the market
Hip International ;21(03): Editorial

4. Introduction
Elevated concentrations of metal ions would monitor and predict MOM implant impending failure - Eskelinen et al ,2014
Elevated concentrations of metal ions not linked to MOM implant failure – Saito et al , 2010
Accurate cup placement is crucial in MOM - Brodner et al,2004
Great variability on the methods used to measure these parameters : safety limits unknow yet – JAAOS :Jacobs J , 2011
Co: 3 micrograms / liter max.
Cr : 0,7 a 2,2 micrograms / liter max.
Versieck et al ,1978

5. Objectives
To determine whether is there any significant difference in metal ion levels and functional outcomes among :
28 mm. heads metal-on-polyethylene bearings
28-32 mm. heads MOM implants
Larger than 32 mm. heads MOM implants
To assess whether these data would be predictive of implant impending failure

6. Methods
Observational cross-sectional study , informed consent obtained
Cohort : 355 pts jan jun., single surgeon ,2 institutions
Same surgical approach, uniform conditions, no resurfacings
69 individuals , 3 total hip systems assessed (n = 69) :
29 pts. metal-on-poly 28 mm. heads Plasmacup (Aesculap)- control
20 pts. MOM 28 and 32 mm. heads Metasul (Sulzer) /Perfecta (Wright)
20 pts. MOM mm. heads Conserve/Perfecta (Wright)

7. n=69
HHS : 90 – 100 points
Cup inclination in the Lewineck safe zone (40º+ - 10° ABD / 15°+-10 AV)
All well functioning and radiografically fixed implants
Follow-up : months (mean : 36 months)
Co , Cr levels ,kidney and liver function assessed

8. Methods
Serum blood Co and Cr levels measured by graphite furnace atomic absorption spectroscopic – GFAAS:
Same laboratory , uniform conditions
Statystical analysis : SPSS 19.0 (Chicago,Il)
Significance level : 95%( p<005)
Tests :Shapiro-Wilk e Kolmogorov-Smirnov, ANOVA
Logistic regression

9. Results MOM >32mm heads:
Cobalt levels above other groups but within limits
Higher prevalence of Cr levels above reference (p<001)
Out liers : 02 LDH implants in the “run-in wear” phase
No differences in GGT, Creat., TGO,TGP among groups
All individuals with normal kidney and liver function
Frequency
Chromium
Below inferior reference limits
87,0 %
(60/69)
Above reference limits (> 2,2 µg/ℓ)
13,0 %
(9/69)
Cobalt
Below inferior reference limits
100 %
(69/69)
Above reference limits (> 3,0 µg/L)
0 %
(0/69)
Table 1. (cont.)

10. Results Chromium Cobalt Groups p-value Control (P-M1) M-M2 28-32 mm
Groups
p-value
Control (P-M1)
M-M mm
M-M2 > 32 mm
Age(years)
Média ± DP
56,14 ± 12,67
44,40 ± 10,92
48,10 ± 6,84
p=0,001
Mediana (mín-máx)
59 (28-74)
42 (26-65)
48 (36-61)
“FU” (months)
40,28 ± 13,83
46,90 ± 15,69
35,00 ± 15,93
p=0,020
46 (12-58)
54 (16-60)
35 (14-58)

11. Results Chromium Cobalt
Follow-up
p-value
Até 18 meses
> 18 meses
Cr (µg/L)
Média ± DP
1,722 ± 1,979
1,112 ± 0,865
p=0,872
Mediana (mín-máx)
0,80 (0,10-5,50)
0,80 (0,10-3,80)
Co (µg/L)
1,056 ± 0,629
0,963 ± 0,522
p=0,789
0,90 (0,30-2,10)
0,87 (0,10-2,05)
Table 4. Cobalt / Chromium levels related to follow-up time .

12. Results Tests of Normality Kolmogorov-Smirnova Shapiro-Wilk Statistic
Kolmogorov-Smirnova
Shapiro-Wilk
Statistic df
Sig.
Idade
,079 69
,200*
,983
,476
Cromo
,201
,000
,833
Cobalto
,107
,050
,957
,018
GGT
,199
,758
Creatinina
,098
,973
,133
TGO
,076
,980
,318
TGP
,087
,987
,701
FU meses
,144
,001
,912
a. Lilliefors Significance Correction
*. This is a lower bound of the true significance.

13. Discussion
The relationship between metal ions levels, clinical and imaging findings is not fully understood to date - Bozic et al , JAAOS 2012
Higher ions levels associated with mal positioned implants ( abd. > 55º) and brand-related - Experts Panel in Hip International , vol.23 n.1,2013
Reports of MOM implants with poor performance and others with good tracks despite head size : no problems with conventional MOM devices Randelli et at,JA, D’Antonio et al ,JBJS,2009
Elevated ions levels in first months are “normal” in MOM bearings - Amstutz H , JBJS 2010;92(16)
Ions levels tend to normalize with time - Smet K , 2014

14. Conclusions
An association was detected between chromium levels above the control group in the MOM >32mm heads prosthesis
Out liers with Cr levels 2-3 fold above reference : associated with LDH implants in the “run-in-wear” phase (p<0,001)
Metal ions screening to detect a possible impending implant failure should be carefully used only in conjunction with clinical and imaging evaluation.
Correct interpretation of data regarding metal ions levels in THA requires further studies

15. Thank You very much ! Loures,Elmano MD JUIZ DE FORA ,MG - BRAZIL
JUIZ DE FORA ,MG - BRAZIL