Metal Hypersensitivity Research Articles

The impact of allergies on patient-reported outcomes after total hip and knee arthroplasty: a systematic review and meta-analysis.

Metal hypersensitivity has been associated with persistent symptoms after total hip arthroplasty (THA) and total knee arthroplasty (TKA), despite successful joint replacement. Allergies frequently co-occur and have been linked to psychiatric disturbances such as anxiety. There is a knowledge gap regarding the effect of allergies, including metal hypersensitivity, on patient-reported outcome measures (PROMs) after THA and TKA. This study aimed to evaluate the influence of allergies including metal hypersensitivity on PROMs in patients undergoing THA and TKA. A systematic search PROSPERO (CRD42023475972) was conducted using PubMed, EMBASE, Scopus, and Cochrane databases. Studies that compared allergic and non-allergic adults undergoing primary THA or TKA and reported PROMs were included. Methodological quality was assessed using the MINORS criteria. The mean differences (MD) and standardized mean differences (SMD) with 95% confidence intervals (CI) were calculated. Eight studies, involving 33,808 patients, were included. For functional outcomes assessed using SF-12, SF-36, KOOS JR, and HOOS JR, allergic patients demonstrated significantly worse scores (SMD - 0.23, 95% CI -0.36 to -0.09). The WOMAC functional scale also demonstrated poorer results in allergic patients (MD 2.49, 95% CI 0.64 4.35). For pain assessed using the WOMAC pain scale, allergic patients reported significantly greater pain (MD 1.04, 95% CI 0.46 1.62). Changes in mental status assessed using the SF-12 and SF-36 did not show significant differences between the groups (MD -0.46, 95% CI -1.40 to 0.47). In subgroup analysis, patients in the THA subgroup showed significantly worse outcomes (MD -7.20, 95% CI -12.97 - -1.43). This meta-analysis found that patients with allergies, including metal hypersensitivity, generally had worse functional outcomes after THA and TKA than patients without allergies. Further research is required to confirm these findings. Preoperative allergy screening can identify individuals at risk of treatment optimization.

Metal hypersensitivity in trapeziometacarpal arthroplasty: A systematic pattern of progression

Metal hypersensitivity is a rare and often underestimated complication, as shown by the small number of published studies, particularly concerning the upper limbs and the hand. However, the increase in the annual number of trapeziometacarpal arthroplasties underlines the importance of better understanding of this problem.We performed a study based on data from the revision of trapeziometacarpal prostheses to assess the incidence of this complication and to define a sequence of radiological changes to detect metal hypersensitivity.This single-center retrospective study included 37 patients operated on between January 2014 and November 2023 for revision of trapeziometacarpal prosthesis. Ten (27%) had no clearly identified cause of failure.For these 10 patients, we analyzed clinical data and postoperative X-rays. In the 11 revision arthroplasties, 2 patients had no symptoms or radiographic signs suggestive of allergy. Six patients had a-posteriori diagnosis established by allergy testing, which also identified 2 additional patients, for a total of 8 patients (21% of the initial cohort). In these cases, there was systematic metaphyseal osteolysis of the first metacarpal between 15 days and 1 month after implantation. Clinically, most patients had an asymptomatic period of 2 weeks to 1 month before onset of symptoms and osteolysis, often accompanied by local inflammation.This study found a reproducible pattern of progression, characterized by the appearance of radiographic signs of osteolysis in the first month, followed by clinical deterioration. Although this course is strongly suggestive of a metal hypersensitivity, it is crucial not to exclude the possibility of an infectious cause, which should always be considered.

Use of Electropolishing in Orthodontic Appliances: An Option to Reduce the Risk of Metal Hypersensitivity.

Electropolishing is a common treatment in the industry; however, how it behaves in the mouth and what benefits it can bring over metal dental attachments have not yet been established. Thus, the aim of this study was to determine the levels of corrosion, the released metal ions, and the changes in structural composition in metallic orthodontic appliances following electropolishing treatment. This study included 56 orthodontic brackets and 28 archwires. The samples were subjected to a pH cycle to simulate an oral environment. Using UV-Vis spectrophotometry, the release of metallic particles was evaluated, and using scanning electron microscopy, the structural and composition changes were evaluated. Groups were compared using Student's t-tests with a value of p ≤ 0.05. The cyclical pH solutions showed variations between groups and days (1, 3, 5, 7 and 15), reaching the highest acidification in the self-ligating brackets; the absorbance between solutions did not differ significantly. As seen from the SEM results, the experimental group showed minor irregularities compared with the control groups. The experimental brackets decreased in iron and increased in chromium after electropolishing, while for the NiTi archwires, they decreased in nickel. Therefore, electropolishing treatments in metallic orthodontic attachments improve their surface structure and corrosion resistance could reduce the risk of metal hypersensitivity, mainly from nickel.

An insight into the co-doping effect of d-d transitions of transition metal ions and hypersensitivity of rare-earth ions in multicomponent glass-system

A multicomponent glass system with composition (70B2O3-22.5Bi2O3-5SeO2-2CuO-0.5Sm2O3) was synthesized via the conventional melt-quench technique. X-ray diffraction analysis confirmed the amorphous nature of this glass. The co-doping of transition and rare-earth metal ions results in the gradual decrease in glass transition temperature and improvement in thermal stability as observed from differential scanning calorimetry. The addition of CuO has increased non-bridging oxygens in multicomponent glass system. The increase in non-bridging oxygens results in a decrease in the optical band gap energy of the glass. Various results reveal that the hypersensitive nature of rare-earth ions has been suppressed by the d-d transition. A decrease in the energy band gap upon co-doping of transition and rare earth ions, suggests its applications in the fields of optoelectronics.

The primary stability of a cementless PEEK femoral component is sensitive to BMI: A population-based FE study

The use of polyetheretherketone (PEEK) for cementless femoral total knee arthroplasty (TKA) components is of interest due to several potential advantages, e.g. the use in patients with metal hypersensitivity. Additionally, the stiffness of PEEK closer resembles the stiffness of bone, and therefore, peri-prosthetic stress-shielding may be avoided. When introducing a new implant material for cementless TKA designs, it is important to study its effect on the primary fixation, which is required for the long-term fixation. Finite element (FE) studies can be used to study the effect of PEEK as implant material on the primary fixation, which may be dependent on patient factors such as age, gender and body weight index (BMI). Therefore, the research objectives of this study were to investigate the effect of PEEK vs cobalt-chrome (CoCr) and patient characteristics on the primary fixation of a cementless femoral component. 280 FE models of 70 femora were created with varying implant material and gait and squat activity. Overall, the PEEK models generated larger peak micromotions than the CoCr models. Distinct differences were seen in the micromotion distributions between the PEEK and CoCr models for both the gait and squat models. The micromotions of all femoral models significantly increased with BMI. Neither gender nor age of the patients had a significant effect on the micromotions. This population study gives insights into the primary fixation of a cementless femoral component in a cohort of FE models with varying implant material and patient characteristics.

FEATURES OF USING ORTHOPEDIC IMPLANTS ON AN EXPERIMENTAL MODEL OF SENSITIZATION TO NICKEL (NI)

Introduction. The theme of metal hypersensitivity (MHS) reactions is among the most controversial and complex issues in orthopedic and trauma practice. MHS diagnoses are diagnostically challenging because they are exclusionary diagnoses. It is currently uncertain which biomarkers can reliably predict a potential pathological response to implants.
 The aim of this research is to investigate hypersensitivity reactions to orthopedic implants containing nickel (Ni).
 Materials and methods. This research was conducted on female Wistar rats in accordance with the standards of bioethical principles. To obtain conclusive results, the animals were divided into two experimental groups: with prior sensitization to Freund's adjuvant containing Ni and without it. Nickel plates with a total surface area of 24 mm2 were implanted in the rats under general anesthesia. Five months after the intervention, the animals were removed from the experiment, and histological examination of the obtained samples was conducted. Extracted implants were examined using electron microscopy to assess the implant surface. The local elemental composition of the implants was analyzed using an energy-dispersive spectrometer.
 Results. Under the experimental conditions, it was demonstrated that after 5 months following the operation, a dense connective tissue capsule with an inflammatory infiltrate in the capsule lumen had formed around the implants in the rats. This suggests a possible manifestation of hypersensitivity reactions to implants containing Ni. Electron microscopy of the surface of the extracted implants revealed corrosion phenomena in all the samples. The degree of corrosion was more pronounced in the group of animals with prior sensitization to Ni, and distant particles of Ni were detected, which can be characterized as the beginning of implant degradation.
 Conclusions. A connective tissue capsule forms around the implants, and it was found to be 34.8% denser in animals sensitized to Ni prior to implantation, which may indicate tissue reactions with signs of hypersensitivity. Further research will provide a deeper understanding of the fundamental inflammatory and immunological reactions to metals present in implants. This, in turn, will facilitate the identification of clinically useful applications necessary for the development of diagnostic or prognostic tests for patients with metal implants.

Establishing clinically meaningful ranges of metal hypersensitivity in orthopaedic patients using COVID-19 vaccine-induced adaptive immune responses from fully vaccinated adults

BackgroundThis study aimed to assess metal sensitization ranges among orthopaedic patients by comparing adaptive immune responses in all-comer pre- and post-operative orthopaedic adults who were COVID-19 unvaccinated or vaccinated vs patients with a painful aseptic implant by lymphocyte transformation test (LTT) to SARS-CoV-2-Spike-Protein (SP) and implant metal(s), respectively. MethodsData were retrospectively reviewed from three independent groups: unvaccinated COVID-19 adults (n = 23); fully COVID-19 vaccinated adults (n = 35); unvaccinated, painful aseptic implant patients with history of metal allergy (n = 98). Standard in vitro LTT for SP and implant metal(s) (nickel, cobalt) were performed and rated as negative (stimulation index [SI]<2), mild (SI ≥ 2), positive (SI ≥ 4–15), and high sensitization (SI > 15) adaptive immune responses to tested antigen. ResultsOverall, 17/23 (74%) of unvaccinated adults showed negative to mild LTT ranges, and 35/35 (100%) of vaccinated showed mild to positive LTT ranges to SP. Vaccinated individuals showed significantly higher median SI (16.1) to SP than unvaccinated (median SI, 1.7; P < 0.0001). Most vaccinated adults (94%) showed a lymphocyte SI > 4 to SP, establishing LTT SI ≥ 4 with >90% sensitivity for diagnosing effective COVID-19 adaptive immune responses. Significantly fewer painful orthopaedic patients (41%) showed comparable elevated levels of lymphocyte metal sensitivity at SI ≥ 4 compared to vaccinated group (P < 0.0001). ConclusionsVaccinated adults showed significantly higher lymphocyte SI to SP than unvaccinated indicating that SI ranges ≥4 should be set as unequivocally diagnostic of LTT-positive adaptive immune responses to tested antigen. This analysis supports using higher LTT SI ranges (SI ≥ 4) in diagnosing clinical orthopaedic-related Type IV metal-hypersensitivity responses among orthopaedic patients.

Metal hypersensitivity in foot & ankle orthopaedic surgery: A systematic review

IntroductionMetal hypersensitivity affects 10–15% of individuals. Orthopaedic implants contain various metals and, therefore, metal hypersensitivity may impact patient outcomes. PurposeWe report a systematic review of the literature on metal hypersensitivity in patients undergoing foot and ankle (F&A) surgery. Our goal is to provide an overview presenting symptoms, diagnostic methods, treatment, and clinical outcomes. MethodsA comprehensive literature search of Ovid MEDLINE and EMBASE was performed from its inception (01-Jan 1966) to 23-Nov 2021. MeSH search terms on F&A were used including orthopaedic surgeries, metal types, and hypersensitivity. All full-text, English, experimental and observational studies reporting on metal hypersensitivity in the context of foot and/or ankle surgeries using metallic orthopaedic devices were included. Article screening, critical appraisal, and data extraction was performed by two reviewers. Disagreements were resolved by a third reviewer. ResultsFifteen studies were identified, reporting on 45 patients (18 male and 27 female). Median age was 58 years and mean follow-up was 20.8 months. 42 static and three arthroplasty implants were included. In total, 19 patients (42.2%) were diagnosed with metal hypersensitivity to a constituent of their implant, including two (4.4%) patients diagnosed without metal hypersensitivity testing. Twenty-six patients (57.8%) tested negative to their metal implant components. Of the 19 patients allergic to a constituent of their implant, 14 underwent hardware removal and improved. Four patients were asymptomatic and the last was symptomatic, but not revised. Of these, 23 patients retained their hardware (eight with skin reactions) and two symptomatic patients underwent hardware removal. ConclusionMetal hypersensitivity in the context of F&A surgery is not widely reported. It should be a differential diagnosis in patients who present with hypersensitivity-type symptoms once infection and mechanical failure are ruled out. This data informs a comprehensive algorithm for identifying and treating metal hypersensitivity in F&A patients. Level of evidenceLevel IV.

The lived experiences of metal hypersensitivity

Background Immunological responses to metal ions can occur in people with metal implantable devices. Nevertheless, patients are not routinely asked about metal hypersensitivity nor tested for it prior to surgical procedures. Moreover, we have not identified any published literature on patients’ experiences with this condition. We undertook this study to better understand the experiences of patients with metal hypersensitivity and to determine what information would help them make an informed decision about implantable medical devices with metal compositions. Methods This is a patient-oriented research using an interpretative phenomenological methodology. We enrolled 16 people from five countries (Canada, New Zealand, Spain, the UK, and the USA) who experienced metal hypersensitivity following implantable medical device. We collected data from in-depth, semi-structured interviews focused on pre-procedural patient education and postoperative experiences to elucidate the barriers and opportunities related to metal hypersensitivity. We analyzed the data using interpretative phenomenological analysis. Results The majority were white biological women between the ages of 34 and 65. None of the participants were informed about immunological responses to metals in implants during the consenting process. They encountered many challenges when symptoms of metal hypersensitivity occurred. The outcomes for the few who had the implants removed were mixed. Conclusion Hypersensitivity reactions to metal need to be discussed as part of the consenting process, and additional strategies are needed to mitigate this issue in the health system.

A Comparison of Clinical Outcomes After Total Knee Arthroplasty in Patients With Preoperative Nickel Allergy Receiving Cobalt Chromium or Nickel-Free Implant

BackgroundThe role of metal hypersensitivity reactions in total knee arthroplasty (TKA) failure is debated. There is no consensus on whether use of a more expensive nickel-free implant is indicated for patients who have preoperative nickel allergy. The purpose of this study was to examine the outcome of patients who have preoperative nickel allergy receiving nickel-free or cobalt chromium (CoCr) implants. MethodsThis was a retrospective review of 17,798 patients who underwent 20,324 unilateral primary TKAs between 2016 and 2020. Presence of preoperative nickel allergy was determined (n = 282). Patients were divided into 2 cohorts: those receiving (1) nickel-free or (2) CoCr implants. Clinical outcome scores and revision rates were assessed. Results243 received a nickel-free implant and 39 received a CoCr implant. There was no significant difference in revision rate between the cohorts. Survivorship free of revision was 94% in the CoCr implant cohort and 98% in the nickel-free implant cohort (P = .9). When comparing clinical outcome scores between cohorts, there was no difference in preoperative, 6-week or 1-year Knee Osteoarthritis Outcome Score Joint Replacement, Visual Analog Scale (VAS), Lower Extremity Activity Scale, Patient-Reported Outcomes Measurement Information System (PROMIS), and Veterans RAND 12-item scores between cohorts. ConclusionIn this retrospective cohort study, there was no difference in revision rates or clinical outcomes in patients who had a nickel allergy undergoing primary TKA with CoCr or nickel-free implants. Further studies are needed to determine if nickel allergy is an independent risk factor for worse TKA outcomes in general.

Metal Hypersensitivity Following Total Ankle Arthroplasty: Case Series and Literature Review

Metal hypersensitivity following total ankle arthroplasty (TAA) is an underreported complication that can manifest as dermal, systematic, and orthopaedic-specific symptoms. It is critical to recognize that metal hypersensitivity is a diagnosis of exclusion; only after all other potential sources of failure, such as loosening or infection are ruled out, can this diagnosis be considered. Aside from imaging and common laboratory analysis, skin patch testing, leukocyte migration inhibition test (LMIT), and lymphocyte transformation test (LTT) are the testing options available for metal allergy. With regards to management of metal hypersensitivity, nonoperative modalities involving topical dermatological management are generally preferred. Severe cases of metal allergy may necessitate operative management consisting of explantation of the implant and either revision TAA with a custom hypoallergenic implant or conversion to an ankle fusion. We present 3 cases of presumed metal hypersensitivity following TAA. In all 3 cases, other forms of TAA failure were carefully ruled out. One patient underwent explantation and conversion to hypoallergenic implant, 1 patient underwent explantation and ankle arthrodesis with hypoallergenic hardware, and 1 patient elected for conservative care. In patients who underwent explantation and conversion to hypoallergenic hardware, no further symptoms associated with metal allergy were noted. Additional research is necessary to improve diagnostic accuracy of metal allergy and make treatment options more effective and accessible.Level of Evidence: Retrospective case series, IV.

Hypersensitivity and lymphocyte activation after total hip arthroplasty.

In the last decades total hip arthroplasty (THA) has become astandard procedure with many benefits but also afew still unsolved complications, which can lead to surgical revision in 19-23% of cases. Thus, aseptic loosening and metal hypersensitivity remain challenges. The phenomenon of wear debris causes chronic inflammation, which produces osteolysis and aseptic loosening. Wear debris promotes osteoclast production and inhibits osteoblasts by secretion of pro-inflammatory cytokines. Micro-abrasions can be induced by abrasive, adhesive and fatigue wear and cause aliberation of metal ions, which lead to another immune response elicited mostly by macrophages. Another reaction in the neocapsule can be atypeIV hypersensitivity reaction to various alloys, containing metals such as nickel, cobalt and chromium. Patch testing and the lymphocyte transformation test (LTT) are not the best diagnostic possibilities to exclude apostoperative hypersensitivity reaction, because of the different alignment of the epicutaneous cells compared to the periprosthetic deep tissue. This hypersensitivity reaction is mostly induced by cytokines, which are secreted by macrophages rather than lymphocytes. In cell cultures and in animal studies, multipotent mesenchymal stem cells (MSC) have been shown to play arole in improving initial implant integration, to limit periprosthetic osteolysis and also to reconstitute peri-implant bone stock during implant revision. Thus, MSC might be used in the future to prolong the durability of THA. Abetter understanding of the interactions between primary chronic inflammation, corrosion, osteolysis and hypersensitivity is mandatory to develop new therapeutic strategies, aiming at the reduction of the incidence of implant failures. In this article the underlying immunological mechanisms to aseptic loosening are presented.

Erratum: Team Approach: Metal Hypersensitivity in Total Joint Arthroplasty.

Erratum: Team Approach: Metal Hypersensitivity in Total Joint Arthroplasty.

Irritant Reaction to Titanium Oxalate on Preoperative Patch Testing Before NUSS Procedure

At our institution, we patch test patients for common metal hypersensitivities prior to the Nuss procedure for the correction of pectus excavatum. Recently we detected an increased incidence of positive reactions to titanium oxalate on patch testing that we believe is attributable to irritant reaction rather than true hypersensitivity due to its burn-like appearance. We aim to support this diagnosis of irritant reaction by testing three different formulations of titanium salts on patch testing.

Titanium niobium nitride knee implants are not inferior to chrome cobalt components for primary total knee arthroplasty at medium-term follow-up.

Oxidized zirconium (Oxinium), titanium nitride (TiN) or titanium niobium nitride (TiNbN) coated implants became in recent years available for an increasing amount of total knee arthroplasty (TKA) systems. The hypothesis of this study was that the use of TiNbN-coated components would not lead to inferior results compared to conventional implants and that none of the metal hypersensitivity patients receiving TiNbN-coated implants would require revision for metal allergy. This retrospective study compared 53 Titanium Niobium Nitride coated TKA with 103 conventional chrome cobalt implants of the same design. Patients were evaluated at a minimal follow-up of 3 years. No differences in clinical, radiological or patient-reported outcome measurements were observed between these groups. A survivorship of 96% without differences in revision rates was observed at medium-term follow-up of 6.5years. Metal allergy leading to contact or generalized dermatitis after TKA is very rare and usually linked to chrome or cobalt hypersensitivity. Nickel release from knee implants has not been shown to lead to cutaneous symptoms, but unexplained pain and swelling, peri-prosthetic osteolysis and component loosening remain potential issues not fully understood. The use of coated implants eliminates this factor from the diagnostic equation in case of postoperative dissatisfaction. The use of titanium niobium nitride coated implants for primary knee osteoarthritis in self-reported metal hypersensitivity patients shows similar outcomes and survivorship rates as conventional chrome cobalt TKA, with no revisions for allergy at medium-term follow-up.

Patient Journey Map: Metal Hypersensitivity.

In this study, we highlight patients' experiences with metal hypersensitivity (MH) after receiving implantable medical devices (IMDs). We aim to identify gaps in clinical care and improve outcomes for individuals who have or may be sensitive to metals. Secondary data analysis from a previous interpretative phenomenological qualitative study was utilized. Using patient journey maps, we explored the experiences of 8 individuals from outpatient settings who received IMD and have first-hand experience with MH. We documented their journey from MH symptom recognition to diagnosis and subsequent IMD management. The results reveal that the time frames from device implantation to the treatment of MH varied from 17 to 228 months. The longest phase on the patient journey maps was the symptom recognition phase, which refers to the time between symptom emergence and MH diagnosis. Participants also required extensive healthcare utilization following their initial surgery. These findings emphasize that MH should be considered in differential diagnoses for patients with IMD. Early screening and detection of MH can enhance patient safety, alleviate distress, and reduce unnecessary healthcare utilization.

Team Approach: Metal Hypersensitivity in Total Joint Arthroplasty.

As total joint arthroplasty volume continues to grow nationwide, more uncommon complications such as metal implant hypersensitivity are reported with greater frequency in the literature. Metal hypersensitivity is a challenging diagnosis given the potentially vague symptomology. It should be considered a diagnosis of exclusion, necessitating careful consideration of other potential etiologies of a failing implant before arriving at the final diagnosis of metal hypersensitivity. Patients can experience substantial morbidity from implant rejection and in severe, refractory cases may even require revision arthroplasty and conversion to a hypoallergenic implant. Given the complex nature of the condition, successful treatment of metal hypersensitivity to orthopaedic implants is best achieved through the use of a multidisciplinary, team-based approach. Immunologists, radiologists, and infectious disease physicians as well as orthopaedic surgeons and mechanical engineers are all vital in appropriate diagnosis and treatment of the condition.

Metal hypersensitivity in hip, knee and spine surgery.

The number of implanted joint prostheses and damaged spinal components is steadily increasing. At the same time, rejection of the implanted material is observed in operated patients, which manifests itself in both skin and general reactions, as well as loosening and earlier wear of implanted prostheses, which was previously referred to as aseptic reactions. However, it has been shown that in a significant proportion of patients, rejection of implanted material may be caused by hypersensitivity to a specific metal. For this reason, patients qualified for implantation of foreign material, mainly nickel, titanium, chromium, molybdenum, and other alloys, should be subjected to allergy tests to detect possible risks in the form of metal sensitivity reactions.

No clinical difference at mid-term follow-up between TiN-coated versus uncoated cemented mobile-bearing total knee arthroplasty: a matched cohort study

Nitride-based ceramic coating was introduced into surgical implants to improve hardness, reduce abrasion, and decrease the risk of metal-induced adverse reactions, especially for patients with suspected or identified metal hypersensitivity. The study aimed to evaluate the effectiveness and safety of a titanium nitride (TiN) coated prosthesis with a mobile bearing design. This was a retrospective matched-cohort study from a single center, comparing clinical outcomes between patients receiving either a TiN-coated versus an uncoated cobalt-chromium-molybdenum (CoCrMo) prostheses for primary total knee replacement. Seventeen patients received the TiN prosthesis between 2015 and 2019. These were matched 1:2 with patients receiving uncoated mobile-bearing knee prostheses with the same design manufacturer. Fourteen patients in the TiN group had complete 5-year follow-up data and were compared with 34 patients from the CoCrMo group. The Knee Society Score was 170.6±28.0 (Function subscore 83.7±17.5 and Knee subscore 86.9±13.8) in the TiN group and 180.7±49.4 (Function subscore 87.5±14.3 and Knee subscore 93.2±9.6) in CoCrMo group, with no statistically significant difference (p=0.19). One patient underwent a revision for instability requiring the removal of the implant in the TiN group and none in the CoCrMo group. The survival rates were 92.9% (CI95% 77.3-100.0) and 100.0% in the TiN group and CoCrMo group respectively (p=1.0). TiN-coated TKA with mobile bearing resulted in satisfactory clinical outcomes, and a low revision rate, and there was no complication related to the coated implant. The use of TiN-coated prostheses in case of confirmed or suspected metal allergy provides satisfactory short-term clinic outcomes.

Poor Correlation Among Metal Hypersensitivity Testing Modalities and Inferior Patient-Reported Outcomes After Primary and Revision Total Knee Arthroplasties.

Metal allergy testing may influence clinical decision-making for patients undergoing a total knee arthroplasty (TKA). Limited data were found to examine the consistency of available testing modalities. This study compares different metal allergy test results and clinical outcomes after primary and revision TKAs in patients with and without metal hypersensitivity. Primary (n= 28) and revision (n= 20) TKA patients receiving hypoallergenic implants for metal allergies diagnosed by skin patch testing (SPT), lymphocyte proliferation testing (LPT), or lymphocyte transformation testing (LTT) were retrospectively reviewed. The agreement between tests was assessed by percentage and kappa statistic within patients who used multiple testing modalities. Postoperative clinical outcomes of these patients were compared to those of patients without metal hypersensitivity matched by age (±5 years), body mass index (±5), gender, and follow-up duration (±2 years). SPT and LPT showed weak agreement for nickel and minimal agreement for cobalt. SPT and LTT showed minimal agreement for nickel; weak agreement for titanium, bone cement, vanadium, and zirconium; but strong agreement for chromium and cobalt. LPT and LTT agreement was weak. Compared to matched controls, metal hypersensitivity patients undergoing primary TKAs with hypoallergenic implants experienced less improvement in Knee Society Scores, Veterans RAND 12 physical component scores, and range of motion. Patients undergoing revision TKAs for multiple indications including metal hypersensitivity had worse clinical outcomes with significantly worse improvements in Knee Society functional scores compared to matched controls. Metal allergy tests produce conflicting results. Hypersensitivity patients may experience inferior clinical outcomes even with hypoallergenic implants. Clinician awareness may influence the choice of testing and improve preoperative counseling of this patient population.