Biomedical Engineering Reference
In-Depth Information
Tabl e 4. 3
Estimated (weighed) average percentages of metal sensitivity to nickel, cobalt or
chromium or combinations reported for the given periods by N authors on a grand total of
n patients: average for general population, for patients having well-functioning prostheses and
patients with poorly functioning prostheses
Group
Period
Patients
Sensitive
(
N
)
n
average %
General population
1993(1)
>
500
>
10
Well-functioning prosth.
1974-1981(8)
556
25
Poorly functioning prosth.
1974-1993(7)
315
60
Contact dermatitis, also type IV hypersensitivity, is fortunately more common
than implant-related sensitivity: wrist watches, necklaces, earrings. But it can also
go the other way round. Tilsley and Rotstein (Australia and Tasmania) reported
in 1980 on five cases of patients, where the implant induced contact dermatitis to
watches, earrings or bra clips containing nickel, chromium or cobalt [
145
].
Let us have a look now at a few cases for response to the most common types of
alloys.
We conclude this section by citing a recent paper in
Nature
, where the authors
stress the key role of metalloproteins in most biological processes and state that:
Metal ion cofactors afford proteins virtually unlimited catalytic potential, enable electron
transfer reactions and have a great impact on protein stability [
146
].
The cited paper is discussing only microbial metalloproteomes and focuses on met-
als assimilated by a microorganism (
Pyrococcus furiosus
) and the identification of
its cytoplasmic metalloproteins. A great number of protein fractions associated with
elements like cobalt, zinc, iron, nickel, zinc, tungsten, molybdenum, and vanadium
did not match any known assignation. These observations substantiate our concern
about the potential long-term effects and/or toxicity of major and/or minor elements
present in currently implanted materials.
4.5.1
Stainless Steels
Nickel.
Mid of the 1970s a surgeon had inserted a stainless steel pin in a broken
clavicula of an adult female patient (own case study). Two days later, the pin had
to be removed because the patient suffered from a severe atopic eczema. The analy-
sis we performed on a freeze-dried biopsy of this clavicula showed extremely high
concentrations of nickel and chromium but nickel is proportionately more than its
concentration in the alloy: 325 ppm of nickel for 250 ppm of chromium. Average
values for freeze-dried tissue (facie lata) near a stainless steel hip stem are for nickel
6.5 and chromium 5.1 ppm, to be compared to 0.2 and 0.3 ppm, respectively, for
reference tissue [
147
]. It illustrates the affinity of tissue for nickel. This extreme
case was attributed to highly stimulated production of thioneins by this patient.
