United Kingdom
Metal Allergy Screening Prior to Joint Arthroplasty and Its Influence on Implant Choice:
A Delphi Consensus Study Amongst Orthopaedic Arthroplasty Surgeons
Arif Razak, MRCS, Ananthan Dave Ebinesan, MRCS, and Charalambos Panayiotou Charalambous, MD, FRCS
Knee Surg Relat Res. 2013 Dec; 25(4): 186–193.
Introduction
Cutaneous metal allergy as detected by patch testing affects 10% to 17% of the population (1-5). This is mainly to metals such as nickel, palladium, cobalt, and chrome. Joint arthroplasty using metallic implants is one of the most common elective orthopaedic operations with 79,516 primary total knee replacements (TKR) and 71,672 primary total hip replacements (THR) performed in England and Wales in 2011 (6). Therefore, metal allergy screening in joint arthroplasty, particularly in knee joint arthroplasty, can potentially cause surgical delays and additional costs.
Although rare cutaneous reactions have been reported following deep orthopaedic implant usage, the role of metal allergy to ongoing joint pain and early aseptic loosening is still controversial (7-10). Similarly, there is controversy as to whether cutaneous allergy can be indicative of an allergy to deep seated implants (4,11,12).
There are several recommendations available on managing patients with potential metal allergy undergoing joint arthroplasty. Schalock et al. (13) recommended any patient with a prior history of reported cutaneous metal allergy should be patch tested prior to device implantation. Granchi et al. (14) also recommended patch testing for any patient with previous signs or symptoms of metal allergy. Patients with positive skin reaction should not have an implant containing the metal allergen if possible (14).
The aim of our study was to obtain a consensus among joint arthroplasty surgeons who are considered experts in their field within the UK on metal allergy screening prior to joint arthroplasty surgery and its implication on implant choice.
Materials and Methods
The Delphi technique was used to combine expert opinion anonymously into a group consensus. The Delphi method involves questionnaires being given to a panel of experts with regards to a given topic, in this case metal allergy and joint arthroplasty. This was repeated until a consensus was obtained amongst this panel.
1. Invited Experts
Ninety joint arthroplasty experts in the UK were identified through a PubMed/Medline database search. They were selected based on these criteria: recent publications on knee/hip/shoulder joint arthroplasty topics in a PubMed indexed journal and currently working as an orthopaedic surgeon in an NHS hospital within the UK. Sixty experts were knee and/or hip arthroplasty surgeons and the other 30 experts were shoulder/upper limb arthroplasty surgeons. The initial online search for the experts was made on the PubMed/Medline database with these keywords: "knee arthroplasty", "hip arthroplasty", "shoulder arthroplasty", and "joint replacements". The publication dates were set between January 2000 and March 2012 inclusive. The senior author of the publication was selected. The author's email address was obtained either from the publication or through Google search. The administered questionnaires were prepared on the survey monkey website (www.surveymonkey.com). A cover letter explaining the details of the study together with the website link to this questionnaire was sent to the authors' email address. No incentives were offered for participating in the study.
Two separate questionnaires were made, one knee and hip questionnaire and one shoulder questionnaire. The knee and hip questionnaire was sent to the knee/hip expert group and the shoulder questionnaire was sent to the shoulder expert group. The questions in the 2 questionnaires were the same apart from the type of joint (knee, hip, shoulder) they were referring to. The questionnaire enquired about the joint arthroplasty experience of the recipients, their views on various allergy signs and symptoms, investigations for metal allergy prior to joint arthroplasty and the influence of such investigations on implant choice. Experts who did not respond initially received the questionnaire again with a 2 week interval until a response was obtained. Overall, the questionnaire was sent to the non-responders 4 times over a 3 month period.
The responses from the first round of questionnaires were analysed and the second round of questionnaires were formulated based on the most popular answers.
In the second round questionnaire, the experts who replied to the first round were contacted again. They were asked whether or not they agreed with the most popular responses of the first questionnaire round. The questionnaire was sent to the non-responders with repeated attempts up to 4 times over a period of 2 months.
Eighteen experts completed the first round questionnaire and 17 of those completed the second round questionnaire.
Results
1. Round 1
The responders were 16 knee and/or hip surgeons and 2 shoulder surgeons.
Eleven experts agreed that patients should not be routinely asked about metal allergy prior to surgery. At least 10 experts considered localised blistering, rash or systemic anaphylactic reactions when in contact with metal as indicative of a metal allergy. Seven experts would proceed with surgery (cobalt chromium or stainless steel implants) if a metal allergy is suspected in patients about to undergo joint arthroplasty surgery. Six experts, however, would refer these patients for patch testing before surgery. In a patient with positive patch test for cobalt, chromium or nickel, 7 experts would still use cobalt chromium or stainless steel implant while 6 experts would use titanium or other nickel free implant. In a patient with negative patch test but with a history of local reaction to metal, 16 experts would use cobalt chromium or stainless steel implant. In a patient with negative patch test but with a history of generalised reaction to metal, 14 experts would use cobalt chromium or stainless steel implant.
2. Round 2
The responders were 16 knee and/or hip surgeons and 1 shoulder surgeon.
Sixteen experts agreed that patients should not be routinely asked about metal allergy prior to surgery. Fourteen experts agreed on localised blistering, hives and rash, generalised body swelling and systemic anaphylactic reactions when in contact with metal as indicative of metal allergy. Fourteen experts agreed that they would proceed with cobalt chromium or stainless steel implant even if a metal allergy is suspected. Twelve experts agreed that they would still use cobalt chromium or stainless steel implant in patients with positive patch test for cobalt, chromium or nickel. The majority of experts would still use cobalt chromium or stainless steel implant in patients with a negative patch test result but with a history of localised (16 experts) or generalised reactions (15 experts) to metal.
Discussion
The implications of metal allergy to joint arthroplasty surgery remain a topic that is still not fully appreciated in research. This study was carried out to obtain a consensus amongst joint arthroplasty surgeons on metal allergy screening prior to joint arthroplasty surgery and its implication on implant choice.
The Delphi method has been widely used as a research tool in many fields such as healthcare and education (15). It involves several rounds of questionnaires sent to a panel of experts until a consensus is reached. The Delphi method is often used for an issue for which there is limited scientific or clinical evidence, and hence the opinions of experts are sought. There are several advantages of the Delphi methodology. Each expert is unaware as to who the remaining participants are, hence any bias in expression of opinion is limited. The Delphi method also makes it easier to bring together a group of experts, and there is no geographical limit as to the participants involved (16). Although absolute agreement is often not achieved, a predefined level of agreement amongst experts is necessary for consensus to be reached. There is no standard cut off point for consensus with a cut off limit of 51% (17) to 70% employed previously15,18). Because of our small number of experts, we used a minimum of 60% of experts' agreement as a consensus.
Our results suggest that although absolute agreement could not be obtained, a consensus (defined as >60% agreement) was reached for most of the issues examined. This included that patients having metal arthroplasty should not be routinely questioned about metal allergy prior to surgery. It seems the panel felt that patients with troublesome history of metal allergy would offer this history when asked about allergies in general and hence specific questioning may not be essential. Amongst the signs of metal allergy presented to the panel, only localised blistering, hives and/or rash, generalised body swelling and systemic anaphylactic reactions when in contact with a metal were considered indicative of a potential metal allergy, with milder reactions not considered significant.
The panel agreed to proceed with traditional cobalt-chromium/stainless steel implants in patients who report local or generalised reactions to metal or jewellery but have negative patch testing. Interestingly, however, a consensus level was also reached in using traditional cobalt-chromium/stainless steel implants in patients patch testing positive for cobalt, chromium or nickel. The panel also felt that even if a metal allergy is suspected, a patch test is not necessary to be done to confirm the presence of metal allergy. These responses may signify the lack of strong evidence as to the role of metal allergy on ongoing joint pain and early aseptic loosening (7-10), but also whether cutaneous allergy can be indicative of an allergy to deep seated implants (4,11,12). A systematic review and meta-analysis on metal sensitivity testing in patients undergoing joint arthroplasty showed that its predictive value was not statistically proven even though the paper suggested that patients with a history of metal allergy should be patch tested. It is important to note that our study is based on personal opinion of experts rather than scientific evidence (14). Following the consensus reached here, we could avoid unnecessary extra costs for patch testing and the use of non-standard metal implants such as titanium implants.
A limitation of this study is that only 20% of the surgeons contacted responded to the first round questionnaire. Nevertheless, as it is a Delphi study, the quality of experts' opinions is more important than the actual response rate. The acceptable sample size can be variable and one Delphi study has been reported with only five experts on the panel (19). The fact that all but one participant of the 1st round responded to the 2nd round gives extra strength to our results and conclusions. To our best knowledge, this is the first time a Delphi approach has been used to reach a consensus amongst arthroplasty experts on important metal allergy issues, which again gives high value to our findings.
Conclusions
Our consensus study suggests that routine metal allergy screening prior to joint arthroplasty is not essential. The use of traditional cobalt chromium/stainless steel implants is recommended regardless of the patient's metal allergy status based on this consensus study.
A Delphi Consensus Study Amongst Orthopaedic Arthroplasty Surgeons
Arif Razak, MRCS, Ananthan Dave Ebinesan, MRCS, and Charalambos Panayiotou Charalambous, MD, FRCS
Knee Surg Relat Res. 2013 Dec; 25(4): 186–193.
Introduction
Cutaneous metal allergy as detected by patch testing affects 10% to 17% of the population (1-5). This is mainly to metals such as nickel, palladium, cobalt, and chrome. Joint arthroplasty using metallic implants is one of the most common elective orthopaedic operations with 79,516 primary total knee replacements (TKR) and 71,672 primary total hip replacements (THR) performed in England and Wales in 2011 (6). Therefore, metal allergy screening in joint arthroplasty, particularly in knee joint arthroplasty, can potentially cause surgical delays and additional costs.
Although rare cutaneous reactions have been reported following deep orthopaedic implant usage, the role of metal allergy to ongoing joint pain and early aseptic loosening is still controversial (7-10). Similarly, there is controversy as to whether cutaneous allergy can be indicative of an allergy to deep seated implants (4,11,12).
There are several recommendations available on managing patients with potential metal allergy undergoing joint arthroplasty. Schalock et al. (13) recommended any patient with a prior history of reported cutaneous metal allergy should be patch tested prior to device implantation. Granchi et al. (14) also recommended patch testing for any patient with previous signs or symptoms of metal allergy. Patients with positive skin reaction should not have an implant containing the metal allergen if possible (14).
The aim of our study was to obtain a consensus among joint arthroplasty surgeons who are considered experts in their field within the UK on metal allergy screening prior to joint arthroplasty surgery and its implication on implant choice.
Materials and Methods
The Delphi technique was used to combine expert opinion anonymously into a group consensus. The Delphi method involves questionnaires being given to a panel of experts with regards to a given topic, in this case metal allergy and joint arthroplasty. This was repeated until a consensus was obtained amongst this panel.
1. Invited Experts
Ninety joint arthroplasty experts in the UK were identified through a PubMed/Medline database search. They were selected based on these criteria: recent publications on knee/hip/shoulder joint arthroplasty topics in a PubMed indexed journal and currently working as an orthopaedic surgeon in an NHS hospital within the UK. Sixty experts were knee and/or hip arthroplasty surgeons and the other 30 experts were shoulder/upper limb arthroplasty surgeons. The initial online search for the experts was made on the PubMed/Medline database with these keywords: "knee arthroplasty", "hip arthroplasty", "shoulder arthroplasty", and "joint replacements". The publication dates were set between January 2000 and March 2012 inclusive. The senior author of the publication was selected. The author's email address was obtained either from the publication or through Google search. The administered questionnaires were prepared on the survey monkey website (www.surveymonkey.com). A cover letter explaining the details of the study together with the website link to this questionnaire was sent to the authors' email address. No incentives were offered for participating in the study.
Two separate questionnaires were made, one knee and hip questionnaire and one shoulder questionnaire. The knee and hip questionnaire was sent to the knee/hip expert group and the shoulder questionnaire was sent to the shoulder expert group. The questions in the 2 questionnaires were the same apart from the type of joint (knee, hip, shoulder) they were referring to. The questionnaire enquired about the joint arthroplasty experience of the recipients, their views on various allergy signs and symptoms, investigations for metal allergy prior to joint arthroplasty and the influence of such investigations on implant choice. Experts who did not respond initially received the questionnaire again with a 2 week interval until a response was obtained. Overall, the questionnaire was sent to the non-responders 4 times over a 3 month period.
The responses from the first round of questionnaires were analysed and the second round of questionnaires were formulated based on the most popular answers.
In the second round questionnaire, the experts who replied to the first round were contacted again. They were asked whether or not they agreed with the most popular responses of the first questionnaire round. The questionnaire was sent to the non-responders with repeated attempts up to 4 times over a period of 2 months.
Eighteen experts completed the first round questionnaire and 17 of those completed the second round questionnaire.
Results
1. Round 1
The responders were 16 knee and/or hip surgeons and 2 shoulder surgeons.
Eleven experts agreed that patients should not be routinely asked about metal allergy prior to surgery. At least 10 experts considered localised blistering, rash or systemic anaphylactic reactions when in contact with metal as indicative of a metal allergy. Seven experts would proceed with surgery (cobalt chromium or stainless steel implants) if a metal allergy is suspected in patients about to undergo joint arthroplasty surgery. Six experts, however, would refer these patients for patch testing before surgery. In a patient with positive patch test for cobalt, chromium or nickel, 7 experts would still use cobalt chromium or stainless steel implant while 6 experts would use titanium or other nickel free implant. In a patient with negative patch test but with a history of local reaction to metal, 16 experts would use cobalt chromium or stainless steel implant. In a patient with negative patch test but with a history of generalised reaction to metal, 14 experts would use cobalt chromium or stainless steel implant.
2. Round 2
The responders were 16 knee and/or hip surgeons and 1 shoulder surgeon.
Sixteen experts agreed that patients should not be routinely asked about metal allergy prior to surgery. Fourteen experts agreed on localised blistering, hives and rash, generalised body swelling and systemic anaphylactic reactions when in contact with metal as indicative of metal allergy. Fourteen experts agreed that they would proceed with cobalt chromium or stainless steel implant even if a metal allergy is suspected. Twelve experts agreed that they would still use cobalt chromium or stainless steel implant in patients with positive patch test for cobalt, chromium or nickel. The majority of experts would still use cobalt chromium or stainless steel implant in patients with a negative patch test result but with a history of localised (16 experts) or generalised reactions (15 experts) to metal.
Discussion
The implications of metal allergy to joint arthroplasty surgery remain a topic that is still not fully appreciated in research. This study was carried out to obtain a consensus amongst joint arthroplasty surgeons on metal allergy screening prior to joint arthroplasty surgery and its implication on implant choice.
The Delphi method has been widely used as a research tool in many fields such as healthcare and education (15). It involves several rounds of questionnaires sent to a panel of experts until a consensus is reached. The Delphi method is often used for an issue for which there is limited scientific or clinical evidence, and hence the opinions of experts are sought. There are several advantages of the Delphi methodology. Each expert is unaware as to who the remaining participants are, hence any bias in expression of opinion is limited. The Delphi method also makes it easier to bring together a group of experts, and there is no geographical limit as to the participants involved (16). Although absolute agreement is often not achieved, a predefined level of agreement amongst experts is necessary for consensus to be reached. There is no standard cut off point for consensus with a cut off limit of 51% (17) to 70% employed previously15,18). Because of our small number of experts, we used a minimum of 60% of experts' agreement as a consensus.
Our results suggest that although absolute agreement could not be obtained, a consensus (defined as >60% agreement) was reached for most of the issues examined. This included that patients having metal arthroplasty should not be routinely questioned about metal allergy prior to surgery. It seems the panel felt that patients with troublesome history of metal allergy would offer this history when asked about allergies in general and hence specific questioning may not be essential. Amongst the signs of metal allergy presented to the panel, only localised blistering, hives and/or rash, generalised body swelling and systemic anaphylactic reactions when in contact with a metal were considered indicative of a potential metal allergy, with milder reactions not considered significant.
The panel agreed to proceed with traditional cobalt-chromium/stainless steel implants in patients who report local or generalised reactions to metal or jewellery but have negative patch testing. Interestingly, however, a consensus level was also reached in using traditional cobalt-chromium/stainless steel implants in patients patch testing positive for cobalt, chromium or nickel. The panel also felt that even if a metal allergy is suspected, a patch test is not necessary to be done to confirm the presence of metal allergy. These responses may signify the lack of strong evidence as to the role of metal allergy on ongoing joint pain and early aseptic loosening (7-10), but also whether cutaneous allergy can be indicative of an allergy to deep seated implants (4,11,12). A systematic review and meta-analysis on metal sensitivity testing in patients undergoing joint arthroplasty showed that its predictive value was not statistically proven even though the paper suggested that patients with a history of metal allergy should be patch tested. It is important to note that our study is based on personal opinion of experts rather than scientific evidence (14). Following the consensus reached here, we could avoid unnecessary extra costs for patch testing and the use of non-standard metal implants such as titanium implants.
A limitation of this study is that only 20% of the surgeons contacted responded to the first round questionnaire. Nevertheless, as it is a Delphi study, the quality of experts' opinions is more important than the actual response rate. The acceptable sample size can be variable and one Delphi study has been reported with only five experts on the panel (19). The fact that all but one participant of the 1st round responded to the 2nd round gives extra strength to our results and conclusions. To our best knowledge, this is the first time a Delphi approach has been used to reach a consensus amongst arthroplasty experts on important metal allergy issues, which again gives high value to our findings.
Conclusions
Our consensus study suggests that routine metal allergy screening prior to joint arthroplasty is not essential. The use of traditional cobalt chromium/stainless steel implants is recommended regardless of the patient's metal allergy status based on this consensus study.
