Background: Nickel is the most common metal sensitizer in humans
with a prevalence of approximately 14%. The effects of nickel
allergy on the performance of an orthopaedics implant are
unclear and there are no UK guidelines on the use of nickel free
implants for joint replacement surgery in patients with a
history of nickel allergy.
This cohort study looks at the current practice of surgeons in
Scotland in their approach to nickel allergy and use of nickel
free implants in the patient undergoing major joint replacement
Methods: An anonymous questionnaire was sent to all orthopaedic
consultants in the west of Scotland.
Results: Eighty-seven questionnaires were sent, with a response
rate of 63.2% (55 replies). 54.5% (30) did ask patients if they
had a nickel allergy. 86.7% (26) of these would go on to use a
nickel free implant when the patient gave a history of allergy.
Of the 25 who did not ask about nickel allergy, 72% (18) would
use a nickel free implant if they knew that the patient was
allergic to nickel.
Only 12.7% (7) stated that they did have a unit policy for the
use of implants in a nickel allergic patient.
Conclusions: This variation in practice is likely to be a
reflection of the lack of evidence and guidance on this topic.
It suggests that there is a variation in opinion amongst
surgeons of the importance of a cutaneous hypersensitivity and
its potential effects on the performance of an implant placed
deep within the tissues. Further research is needed before
evidence based decisions can be made on the use of nickel free
Nickel is the most common metal sensitizer in humans, with a
prevalence in the general population of approximately 14% (1).
Amongst the metal alloys most commonly used in orthopaedic
practice, nickel is contained in stainless steel (13-15.5%) and
in cobalt/chrome implants (1%) (2). Titanium alloys do not
contain nickel and can therefore be used as an alternative to a
nickel containing implant. Since all metals implanted into human
tissue undergo corrosion, it is reasonable to suppose that metal
ion complexes may have the potential to produce a host immune
There are no UK or Scottish guidelines on the use of nickel free
implants or on the use of metal implants in nickel allergic
patients. We conducted a cohort study to examine the current
practice of orthopaedic surgeons in the West of Scotland, UK, to
examine their approach to nickel allergy and the use of implants
in the nickel allergic patient undergoing hip or knee joint
An anonymous questionnaire was sent to all orthopaedic
consultants in the West of Scotland. They were given an
addressed envelope in which to return the competed questionnaire
to the first author of this paper.
Eighty-seven questionnaires were sent and the response rate was
63.2% (55 replies). 54.5% (30) of consultants did ask patients
if they had a history of nickel allergy during their
pre-operative assessment. Of those respondents who checked for a
history of nickel allergy, 86.7% (26) would use a nickel free
implant on the basis of a positive history.
In the group who did not routinely ask about a history of nickel
allergy pre-operatively (25), 72% (18) would use a nickel free
implant if they were made aware that the patient did have a
history of allergy to nickel.
Out of the total number of responses, only 12.7% (7) stated that
they did have a unit policy on the use of nickel free implants.
Currently there is limited evidence and understanding of the
effects of cutaneous nickel hypersensitivity reactions to the
performance of orthopaedic implants. In a recent extensive
review of available literature, Hallab et al (2) cite a number
of case reports specific to orthopaedic practice, which
implicate the implantation of a metal prosthesis in causing a
cutaneous allergic reaction (3-8). These cases do not all
involve nickel, but they do highlight a possible role for the
avoidance of metal allergens in known hypersensitive patients.
In a number of cases the reaction necessitated removal of the
implant, with an improvement in the cutaneous symptoms noted in
It is also important to consider the potential for metal ion
wear particles to impair the performance of the prosthesis
resulting in early failure. Hallab (2) goes on to statistically
analyse the data from 7 cohort studies. He concludes that; “the
average prevalence of metal sensitivity among patients with a
failed or poorly functioning implant (as judged by a variety of
criteria) was approximately 60%”. Seven investigations were
included (9-15). However, as they state, “this association does
not prove a causal effect”.
In their conclusion, they advise that implant degradation
products have been shown to be associated with dermatitis,
urticaria and vasculitis. They also noted that the prevalence of
dermal hypersensitivity in patents with a joint replacement
device, particularly those with a failed implant, is
substantially higher than that in the general population.
However, a clear causal relationship between implant degradation
products and impaired performance or failure of a metal
prosthesis has not yet been proven. Hallab suggests that until
the roles of delayed hypersensitivity and humoral immune
responses to metallic orthopaedic implants are more clearly
defined, the risk to patients may be considered minimal.
In this cohort it is clear that attitudes towards the importance
of nickel allergy and the use of nickel free implants varies
considerably amongst orthopaedic surgeons despite working in the
same unit or those in a close geographical area.
It is likely that the variation in practice reflects the lack of
understanding and guidance in this area of orthopaedic practice.
This most probably also accounts for the small number of
surgeons working within a unit with a policy covering the use of
It is unlikely that a consensus will be reached on the use of
nickel free implants until further research into the roles of
immune responses to metal implants allows evidence-based
decisions to be made. Until then, recommendations on the use of
metal implants in metal hypersensitive individuals will not be
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