Vol.2, No.4, 306-310 (2010) Health
Copyright © 2010 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
Titanium allergy or not? “Impurity” of titanium implant
Thomas Harloff1, Wolfgang Hönle2, Ulrich Holzwarth3, Rainer Bader4, Peter Thomas5,
Alexander Schuh1
1Research Unit, Neumarkt Clinical Center, Neumarkt, Germany
2Orthopedic Clinic Neumarkt, Neumarkt, Germany
3MedTitan, Erlangen, Germany
4Orthopedic Clinic and Polyclinic, University of Rostock, Rostock, Germany
5Clinic and Polyclinic for Dermatology and Allergology of the Ludwig-Maximilians-University of Munich, Munich, Germany;
Received 25 December 2009; revised 26 January 2010; accepted 30 January 2010.
For patients suffering from allergies to nickel,
chrome and cobalt, titanium implants are the
implants of choice. Nevertheless, titanium im-
plant sensitivity has been reported in the form
of “allergies” and an increasing number of pa-
tients are confused. This paper aims to use
spectral analysis as a diagnostic tool for ana-
lyzing different titanium implant alloys in order
to determine the percentage of the alloy com-
ponents and additions that are known to cause
allergies. Different materials, such as sponge
titanium, TiAl6Nb7, Ti21SRx, TiAl6V4 [forged
alloy], TiAl6V4 [cast alloy], TMZF, pure titanium
[c. p. 1] and iodide titanium were analyzed for
the presence of the elements that have been
associated with allergic reactions using spectral
analysis. All the implant material samples con-
tained traceable amounts of Be, Cd, Co, up to a
maximum of 0.001 percent by weight [wt.%], Cr
up to 0.033 wt.%, Cu up to 0.007 wt.%, Hf up to
0.035 wt.%, Mn up to 0.007 wt.%, Ni up to 0.031
wt.%, and Pd up to 0.001 wt.%. This paper
demonstrates that all the investigated implant
material samples cont ain ed a lo w but consistent
percentage of components that have been as-
sociated with allergies. For example, low nickel
contents are related to the manufacturing pro-
cess and are completely dissolved in the tita-
nium grid. Therefore, they can virtually be clas-
sified as “impurities”. Under certain circum-
stances, these small amounts may be sufficient
to trigger allergic reactions in patients suffering
from the corresponding allergies, such as a
nickel, palladium or chrome allergy.
Keywords: Allergy; Implant; Nickel; Spectral
Analysis; Titanium
Numerous studies on allergic reactions to synthetic ma-
terials have been carried out, in particular on allergic
reactions to metallic components that are also used in
orthopedic surgery. In case histories, localized or gener-
alized eczemas, urticaria, persistent swelling, sterile os-
teomyelitis and cases of aseptic implant loosening are
described as examples of allergic reactions to metal im-
plants [1-28]. Nickel, cobalt and chrome are the classic
contact allergens [1,2,11,29-32]. However, in contrast to
the sensitization ratio of up to 12 percent of the general
population to nickel and of up to 5 percent to cobalt and
chrome [24,32], only a few cases of allergies to implant
materials have been documented. Precise details on the
frequency of such reactions are presently not available.
Furthermore, up to now, the frequency of allergic reac-
tions occurring in the peri-implant region, without any
prior patch test reactions, has not been established. For
example, inflammatory infiltrations of the peri-implant
region displaying characteristics of late-type allergic
reactions were found in a number of patients undergoing
revision operations related to complications [2]. Thomas
[24] and Willert [27] published cases of endoprosthesis
loosening with accompanying T-lymphocyte-dominated
immune reactions in the peri-implant region. In the
1970s, obvious allergic reactions to the cobalt-chrome
alloy components of the McKee-Farrar prosthesis un-
derwent scrutiny for the first time [3,11]. In case of a
nickel allergy, individual responsiveness can be very
diverse, with even minute quantities of nickel causing
contact eczemas in sensitive patients [3,11,32]. Their
high resistance to corrosion, the absence of any carcino-
genic risk, their excellent bio-compatibility and their
T. Harloff et al. / Health 2 (2010) 306-310
Copyright © 2010 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
lack of sensitization make titanium implants or titanium
alloy implants the recommended alternative for patients
with nickel, cobalt or chrome allergies [33,34]. Admit-
tedly, there are also reports of incompatibility reactions
to titanium materials [10,25,35-42]. In his study, Walsh
[42] found several eyeglass frames made of a titanium
alloy to contain nickel traces. Likewise, Suhonen [41]
documented allergic contact dermatitis caused by tita-
nium eyeglass frames. However, in Suhonen’s case, pal-
ladium was established as the causative factor.
In his comparative histological and immuno-histo-
chemical analysis of tissues surrounding titanium im-
plants [n = 23] and implant steel [n = 8], Thewes [23]
documented the presence of peri-vascular infiltrations,
Langerhans cells, T helper cells, T suppressor cells,
monocytes, macrophages and memory cells, and did not
find any statistically significant difference between both
groups of implants. Thewes concluded that a metal sen-
sitization to both steel implants and titanium implants is
possible. Yamauchi [43] described an eczema reaction in
connection with a pacemaker made of titanium. Lalor et
al. [38] analyzed the granuloma tissue of five patients
that had undergone a revision operation following an
aseptic prosthesis loosening. The granuloma tissue was
found to contain primarily titanium. Each of the five
patients subjected to scratch testing using diluted solu-
tions of titanium salts yielded negative results. However,
two of the patients displayed a positive skin reaction to
titanium-containing ointments.
These above mentioned reports led to more and more
confused patients. This paper aims to examine different
titanium implant alloys in respect to impurity with com-
ponents that are known to potentially cause allergies.
A Spectrolab spectral analysis unit from the Spectro
company [Kleve, Germany] was used to study the tita-
nium materials [listed in Table 1 with their respective
producers]. Prior to the test, the optical analysis unit was
calibrated using calibrated samples, the chemical com
Table 1. Materials analyzed.
Materials Producer/Supplier
Sponge titanium Source Japan
Sponge titanium Source Russia
Ti21SRx TIMET Laboratories, Henderson,
TiAl6V4 Allvac Teledyne, Monroe, USA
FG-TiAl6V4 ASTM F 1108
TMZF Stryker
Pure titanium rod, Ti-2 TIMET
Pure titanium plate, Ti-1 Deutsche Titan
Iodide titanium Metallgesellschaft Ff/M
position of which was determined via optical spectral
analysis by sparking sample slices [with a diameter of
6-60 mm and a thickness of 6 mm] under argon atmos-
phere using a 6 mm ceramic aperture. In this particular
case, the measuring depth obtained by sparking is 0.5
mm, making the thickness of the examined samples ir-
relevant. The described method pertains to a material
analysis and not to a layer analysis. A detailed analysis
was performed on pure titanium slices with a diameter of
6 and 12 mm.
TiAl6V4 slices with a diameter of 10, 16, 22, 35 and
60 mm, respectively, and TiAl6Nb7 slices with a diame-
ter of 14.5, 22 and 28 mm, respectively. Samples of rods
with different diameters were analyzed because the
various titanium alloys of the individual manufacturers
are available with different diameters. The analyses were
performed according to the established and [statistically]
recognized measuring methods used in material science
for determining alloy components. Since it has to be
assumed that the material is homogeneous over the en-
tire length of the respective [titanium or titanium alloy]
rod, only a 6 mm thick sample slice was analyzed in
each individual case. Three measurements and a final
verification measurement were conducted. Each of the
results indicated corresponds to the average value ob-
tained from the three measurements, with the standard
deviation being less than 0.01 percent by weight.
The results of the spectral analysis are shown in Table 2.
All the implant material samples contained traceable
amounts of Be, Cd, Co, up to a maximum of 0.001 per-
cent by weight, Cr, up to a maximum of 0.033 percent
by weight, Cu, up to a maximum of 0.007 percent by
weight, Hf, up to a maximum of 0.035 percent by weight,
Mn, up to a maximum of 0.007 percent by weight, Ni,
up to a maximum of 0.031 percent by weight, and Pd, up
to a maximum of 0.001 percent by weight [Table 2].
There is an increasing number of reports of incompati-
bility reactions to titanium materials [10,25,35-42]. All
the titanium materials examined in the present study
clearly showed consistently traceable amounts of addi-
tional components, such as nickel. Although contents
between 0.01 and 0.034 percent by weight are consid-
ered to be insignificant from a metallurgic perspective,
they are subject to discussion in the context of the high
nickel sensitization rate present in the general population.
The levels of additions found in iodide titanium corre-
spond to the expected levels and demonstrate that, in this
context, the absolutely lowest traces of nickel that are
technologically possible can be adhered to, namely close
T. Harloff et al. / Health 2 (2010) 306-310
Copyright © 2010 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
Table 2. Analysis results (n.t.: not traceable).
Material Analysis values in % by weight
Al Be Cd Co Cr Cu Fe Hf Mn Mo Ni Pd V
Sponge titanium (Japan) 0,001 0,001 0,001 0,0010,0020,0070,001 0,0010,0010,001 0,008 0,001 0,001
Sponge titanium (Russia) 0,001 0,001 0,001 0,001 0,0010,0010,002 0,0010,0070,001 0,001 0,001 0,001
TiAl6Nb7 5,980 0,001 0,001 0,0010,0110,0010,1500,0010,0020,001 0,014 0,0010,001
Ti21SRx 0,005 0,001 0,001 0,0010,005n n. 0,0370,0010,00215,00 0,017 0,0010,001
TiAl6V4 5,930 0,001 0,001 0,0010,0330,0010,1600,0010,0040,002 0,031 0,0013,880
FG-TiAl6V4 ASTM F 1108 6,200,0001 0,0001 0,0010,0120,0010,1700,0010,0010,001 0,011 0,0014,15
TMZF 0,005 0,001 0,001 0,0010,0080,0032,0900,0350,00112,00 0,013 0,0010,002
Pure titanium rod, Ti-2, Timet 0,021 0,001 0,001 0,0010,0140,0010,041 0,0010,0020,001 0,013 0,0010,012
Pure titanium Ti-1, Plate
(Deutsche Titan) 0,004 0,001 0,001 0,001 0,0120,001 0,0280,0010,0010,001 0,012 0,0010,001
Iodide titanium 0,003 0,001 0,001 0,0010,0010,0010,010 0,0130,0010,001 0,001 0,001 0,002
to the detection limit of less than 0.001 percent by
weight. All the other samples, independent of the pro-
ducer, were always found to contain a consistently low
percentage of additions, such as nickel, following their
further processing into rods of different sizes [diameters
between 6 and 60 mm were analyzed]. Numerous publi-
cations deal with hypersensitivity reactions to osteosyn-
thesis materials used in the treatment of fractures, the
majority of these materials being stainless steel implants
An immunological response to metals [partly as an
exaggerated allergic reaction] is discussed to be the
cause of impaired wound healing or the delayed healing
of fractures [19]. Allergic reactions to orthopedic im-
plants can thus also necessitate the removal of the im-
plant [24]. Lymphocyte infiltration was discovered in the
peri-prosthetic tissue, indicating T-lymphocyte-related
inflammation components [25-28]. This lymphocyte
infiltration can be considered a component of a delayed
hypersensitivity reaction [DTH, Delayed Type Hyper-
sensitivity] [2,26,27]. Vasculitis with lymphocyte infil-
tration of the vascular walls and substantial fibrin exuda-
tion have been described [11,27,32]. Nickel, cobalt and
chrome can cause allergic reactions in humans [2,19,31],
with nickel being one of the most common contact al-
lergens. The average sensitization ratio in the general
population lies between 2 percent and 12 percent, de-
pending on age, gender and living conditions. In addition
to the typical findings, such as hand eczeme, uncommon
manifestations, such as pseudo-lymphomas or implant-
associated intolerance reactions, are also known to occur
[24]. Many aspects of skin allergies have already been
analyzed, such as thresholds above which allergens, such
as nickel, chrome or cobalt trigger skin reactions, the use
of standardized provocation testing for the detection of
an allergy [patch test], [immuno-] histological character-
istics of such reactions, tracking elements, such as CLA
[cutaneous leukocyte antigen], which allow sensitized
T-cells to migrate into the skin, and the diminishing re-
activity following the avoidance of the allergens for
many years which leads to problems only after repeated
fresh contact with the respective allergen [booster], e.g.
in case of the repeated wear of fashion jewelry. Accord-
ingly, the “Nickel Directive” [31], which applies to items
that have a direct and prolonged contact with the skin,
determines that a maximum of 0.5 μg nickel/cm2/week
can be released and limits the nickel contents in piercing
metals to 0.05 percent. However, such guidelines do not
yet exist for implants or implant materials. In a study
carried out on 242 patients, Swiontkowski et al. [22]
reported a sensitization prevalence of 0.2 percent for
chromium, 1.3 percent for nickel and 1.8 percent for
cobalt. Subsequent to the implantation of orthopedic
implants, the sensitization rate increased to 2.7 percent
for chromium, 3.8 percent for nickel and 3.8 percent for
cobalt. In many cases, only minute amounts of nickel
suffice to trigger allergic reactions, such as contact ec-
zemas [32]. Therefore, titanium implants or titanium-
alloy implants are often used as an alternative for pa-
tients suffering from nickel, chrome or cobalt allergies
[30]. Duchna [10] conducted a study on 112 patients and
did not find any allergic reactions that were associated
with titanium implants. The biocompatibility of titanium
materials [32] is based on the passivation of its surface.
In its intact state, this surface consists of non-conductive
titanium oxide, a bio-inert material that chemically cor-
responds to ceramics. When corrosion occurs due to an
electron flow, an interaction between the body and the
implant takes place. In essence, these interactions are
dependent on the insulation provided by the oxide layers
and thus dependent on the dielectric constant and there-
fore on the insulating effect of the metal oxides. The
higher the dielectric constant is, the better the insulating
effect and the resulting stability in vivo. Depending on
the oxide type, titanium oxide has a value between ε =
48 and ε = 110, with water having a value of ε = 78 [32].
T. Harloff et al. / Health 2 (2010) 306-310
Copyright © 2010 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
In contrast, the dielectric constant for cobalt oxide and
nickel oxide is not measurable [32]. Therefore, an inter-
action with body electrolytes is likely to occur on a
much larger scale than is the case for metals belonging
to the refractory group [oxide formation in milliseconds],
such as titanium, niobium, tantalum, vanadium and their
alloys. Alternatively, “ceramic” coatings, such as tita-
nium-niobium-oxynitride, can be used to artificially pro-
tect implant alloys against corrosion.
Our results demonstrate that titanium materials contain a
small yet consistent percentage of detectable impurities,
such as the elements Al, Be, Cd, Co, Cr, Cu, Fe, Hf, Mn,
Mo, Ni, Pd and V. All the implant material samples thus
contain a consistent yet low percentage of components to
which allergies have been attributed. Under specific cir-
cumstances, even small amounts of elements, such as
palladium, nickel or chromium, suffice to trigger an al-
lergic reaction in patients suffering from the corres-
ponding allergies. However, these allergic reactions
would not be directly attributable to titanium or its alloys,
but rather to the impurities contained therein. Additional
research on the release of the alloy components and the
reaction thresholds of the afflicted patients is urgently
required. Parallel to this research, alternative production
processes should be evaluated by the companies pro-
ducing these metals in order to produce pure titanium
and titanium alloys containing fewer impurities, for use
in the human body. Titanium continues to be the implant
material of choice for patients suffering from allergic
reactions to cement-free implants.
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