Self-Reported Metal Allergy and Early Outcomes After Total Knee Arthroplasty

Nickel allergy does not correlate with function after total knee arthroplasty

PURPOSE

The purpose of this study is to determine if there is a relationship between clinical outcomes and nickel allergy by evaluating asymptomatic total knee arthroplasty (TKA) patients with well-functioning implants through quantitative metal allergy (MA) testing.

METHODS

A prospective case series was performed on 50 patients with well-functioning TKA of various implant types. Inclusion criteria included primary TKA with a minimum 12-month follow-up and Oxford knee score (OKS) ≥ 40. A commercially available Lymphocyte Transformation Test measured the amount of a hypersensitivity lymphocyte immune response after exposure to a particular antigen. MA results were stratified based on the stimulation index (SI). The Cochran-Mantel-Haenzel test was used to test the homogeneity of metal reactivities. The Wilcoxon-Mann-Whitney test was used to compare individual metal SI by gender and the association of OKS and metal SI was ascertained with the Spearman correlation.

RESULTS

Nickel, cobalt, and chromium do not have the same reactivity scores (p < 0.001), and only nickel showed reactive/highly reactive scores. Females were found to have 3.41 times the odds of males for higher Ni reactivity (p = 0.0295, odds ratio [OR], 95% confidence interval [CI] = 3.41 [1.13-10.3]) only. Clinically, there was no correlation between metal SI and OKS score by metal (Ni rho = -0.1779; Co rho = -0.0036; Cr rho = -0.1748).

CONCLUSION

This is the first study looking at MA in well-functioning TKA. There is no correlation between clinical results and nickel reactivity. Surgeons should exercise caution when revising a painful or poorly functioning TKA based solely on a 'positive' Nickel Allergy test and look for other possible reasons for failure.

LEVEL OF EVIDENCE

Level II.

Hypoallergenic Knee Implant Usage and Clinical Outcomes: Are They Safe and Effective?

Background

One of the most debated topics in modern total knee arthroplasty (TKA) is the impact of metal hypersensitivity (MH) as a potential cause of prosthesis failure. Implanting hypoallergenic prostheses to avoid potential problems in suspected cases of MH is one treatment option that can be used in such cases. However, their long-term clinical safety and efficacy are not well proven.

Methods

All literature relevant to modern hypoallergenic implants were reviewed and summarized to provide a comprehensive synopsis. In addition, a detailed literature search was performed on PUBMED, MEDLINE, and Google Scholar to identify all the clinical studies reporting outcomes for hypoallergenic knee implants. Our search was confined to those studies published as full manuscripts in the English language from July 2018 to July 2023.

Results

To minimize the risk of MH, new implant variants have been developed which are either under clinical evaluation or in routine clinical use. These include conventional metal implants with protective coatings (mono- or multilayer) and metal-free implants. However, there is insufficient clinical data to confirm the rationale and effectiveness of using these "hypoallergenic" TKA implants.

Conclusions

Published studies and arthroplasty registry data analyses indicate no significant differences between hypoallergenic and standard TKAs with overall good survival rates. In the future, further high-quality studies are needed to better understand the complexity of this subject.

A Comparison of Clinical Outcomes After Total Knee Arthroplasty in Patients Who Have and Do Not Have Self-Reported Nickel Allergy: Matched and Unmatched Cohort Comparisons

BACKGROUND

The impact of a preoperative self-reported nickel allergy in patients undergoing primary total knee arthroplasty (TKA) remains unclear. The aim of this study was to compare the revision rates and outcomes of patients who have a self-reported nickel allergy undergoing primary TKA to patients who do not have a self-reported nickel allergy.

METHODS

Over 5 years, a total of 284 TKAs in patients who have and 17,735 in patients who do not have a self-reported nickel allergy were performed. Revision rates and differences in preoperative and postoperative patient-reported outcome measures, including Knee Osteoarthritis Outcome Score Joint Replacement (KOOS JR), Visual Analog Scale, Lower Extremity Activity Scale, and the Patient-Reported Outcomes Measurement Information System Mental and Physical Scores, were compared.

RESULTS

Survivorship free of all-cause revision at 1 year was similar for patients who have and do not have a self-reported nickel allergy (99.5% [95% CI (confidence interval): 98.6 to 100.0] versus 99.3% [95% CI: 99.1 to 99.4]), P = .49). Patients who have a self-reported nickel allergy undergoing primary TKA had no difference in KOOS JR, Visual Analog Scale, or Lower Extremity Activity Scale scores at 6 weeks and 1 year and slightly worse Patient-Reported Outcomes Measurement Information System mental and physical scores at 6 weeks compared to patients who did not have an allergy. Matched analysis revealed no difference in 6-week or 1-year KOOS, JR scores between patients who did and did not have a self-reported nickel allergy when stratified by implant class (nickel-free versus standard cobalt-chromium) (P = .113 and P = .415, respectively).

CONCLUSIONS

Patients who have a self-reported nickel allergy can be advised that, on average, their clinical outcome scores will improve similarly to patients who do not have a self-reported nickel allergy, and revision rates will be similar.

Metal implant allergy: A retrospective cohort analysis at a university allergy practice

Background: Concern of metal sensitization in pre- and postsurgical evaluation is growing, with the recent guidelines remaining the criterion standard for consideration of patch testing. Information remains scarce on surgical screening in the groups of patients who reported a history of metal sensitivity versus those with no reported history. Objective: The objective of this study was to assess the utility of patch testing in surgical candidates based on reported metal allergy history. The secondary objective was to evaluate the utility and outcomes in postsurgical patch testing. Methods: Nine hundred and thirty-one patient charts of patients with the diagnosis of "contact dermatitis" who underwent an evaluation at a single allergy clinic site between January 2013 and December 2022 were identified and reviewed as part of a retrospective chart review study. Patients were included in subgroups based on the time of patch testing and history of reported metal allergy. Results: In all, 67 patients underwent patch testing, 10 (14.9%) of whom were surgical candidates without a history of metal sensitivity, 31 (46.2%) of whom were surgical candidates with a history of metal sensitivity, and 26 (38.8%) of whom were postsurgical patients. Twenty-nine (43.3%) of patients had positive patch testing results, with only one (10%) in the presurgical group, 17 (54.8%) in the presurgical with a history of metal sensitivity, and 11 (42.3%) in the postsurgical group. Zero patients in our cohort without metal sensitivity who were undergoing the Nuss procedure had positive reactions on patch testing, whereas two of four (50%) with reported metal sensitivity who were undergoing the Nuss procedure had positive relevant metal reactions. Conclusion: Ambiguity in the utility of patch testing for surgical decision making remains, despite common utilization. Recent guidelines along with coordination of care among the surgeon, allergist, and patient remains the criterion standard of care.

Understanding immune-mediated cobalt/chromium allergy to orthopaedic implants: a meta-synthetic review

BACKGROUND

The frequency of primary joint replacement surgery continues to increase worldwide. While largely considered biologically inert entities, an increasing body of evidence continues to validate a not insignificant incidence of allergic reactions to such implants. Little previous work has explored genuinely immune-mediated reactivity in this context. In the absence of a contemporary published summary on the topic, this paper explored the current state of understanding of cobalt/chromium allergy and proposes a patient management algorithm whereby such immune reactions are clinically suggested.

METHODS

A structured, systematic literature review was performed by following PRISMA search principles to provide an updated review of this area.

RESULTS

Thirty-six topic-related articles were identified, the majority reflecting lower tiers of scientific evidence with a lack of homogeneous quantitative data to facilitate valid cohort comparisons. Largely, the available literature represented small case series' or expert opinions.

CONCLUSIONS

Despite increasing clinical awareness and acknowledgement of true allergy to joint replacement components, this review highlighted that the evidence base underpinning the diagnosis and management of such patients is limited. Both patient-reported metal allergy or skin patch testing are grossly unreliable methods and show almost no correlation with true immune reactivity. Recent studies suggested a potential role for patient-specific in vitro cellular activation testing and/or targeted genetic testing when cobalt/chromium allergy is clinically suspected. However, while likely representing the contemporary "best available" approaches both can be costly undertakings, are not yet universally available, and still require broader validation in non-research settings before wider uptake can be championed.

Do Patients With Hypoallergenic Total Knee Arthroplasty Implants for Metal Allergy Do Worse? An Analysis of Health Care Utilizations and Patient-Reported Outcome Measures

BACKGROUND

Metal allergy is a rare and controversial cause of implant failure and poor outcomes following total knee arthroplasty (TKA). Few studies have investigated clinical and patient-reported outcome measures (PROMs) in patients treated with hypoallergenic implants. This investigation aimed to compare: (1) health care utilizations (eg, hospital length of stay, 90-day readmission rate, and incidence of nonhome discharge) and (2) 1-year PROMs between patients who received hypoallergenic and standard TKA implants.

METHODS

This was a retrospective review of prospectively collected data from patients who underwent primary TKA between 2018 and 2019. Propensity score matching (3:1) was used to compare standard TKA patients with those who received hypoallergenic TKA implants, respectively. Knee injury and Osteoarthritis Outcome Score (KOOS) pain, KOOS Physical function Shortform (PS), and Veterans RAND 12-Item Health Survey Mental Component Score were collected preoperatively and at 1-year. After matching, 190 hypoallergenic and 570 standard TKAs were analyzed.

RESULTS

No differences were observed in length of stay (P = .98), 90-day readmission (P = .89), and nonhome discharge (P = .82). Additionally, there was no significant difference in change from preoperative to 1-year PROMs (KOOS pain, P = .97; KOOS PS, P = .88; Veterans RAND 12-Item Health Survey Mental Component Score, P = .28). Patient-reported satisfaction was similar at 1-year (P = .23). Patients achieved similar rates of Patient Acceptable Symptom State (PASS) and minimal clinically important difference (MCID) for KOOS pain (PASS, P = .77; MCID, P = .33) and KOOS PS (PASS, P = .44; MCID, P = .65).

CONCLUSION

Patients treated with hypoallergenic TKA implants for suspected metal allergy had similar outcomes compared to patients who had standard implants and no metal allergy.

A comparison of clinical outcomes after total knee arthroplasty (TKA) in patients with preoperative nickel allergy receiving Cobalt-Chromium (CoCr) or Nickel-Free Implant

INTRODUCTION

The 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 pre-operative nickel allergy. The purpose of this study was to examine the outcome of patients who have pre-operative nickel allergy receiving nickel-free or cobalt chromium (CoCr) implants.

METHODS

This was a retrospective review of 17,798 patients who underwent 20,324 unilateral primary TKAs between 2016 and 2020. Presence of pre-operative 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.

RESULTS

243 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=0.9). When comparing clinical outcome scores between cohorts, there was no difference in preoperative, 6-week or 1-year Knee Osteoarthritis Outcome Score Joint Replacement (KOOS JR.), Visual Analog Scale (VAS), Lower Extremity Activity Scale (LEAS), Patient-Reported Outcomes Measurement Information System (PROMIS), and Veterans RAND 12-item (VR12) scores between cohorts.

CONCLUSIONS

In 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.

A Novel Multilayer-Coating for Total Knee Arthroplasty Implants is Safe - 10-Year Results From a Randomized-Controlled Trial

BACKGROUND

This randomized-controlled trial was initiated to compare a new multilayer hypoallergenic coating system with the standard implant in total knee arthroplasty (TKA) in terms of serum metal ion levels, patient-reported outcomes (PROs), and implant survival.

METHODS

A total of 120 patients were randomized to receive a coated or standard TKA of the same knee system. Serum metal ion levels (ie, cobalt, chromium, molybdenum, and nickel) as well as knee function (Oxford Knee Score, OKS), quality of life (SF-36), and physical activity (UCLA activity scale) were assessed before surgery and until the 10 year follow-up. A total of 24 patients died and there was one revision in each group. This resulted in 85 patients who completed follow-up.

RESULTS

Both groups demonstrated equally good improvement in PROs after surgery and constant score values thereafter. The majority of patients had metal ion serum levels below detection limit. Only cobalt levels demonstrated a slight increase in the standard group at 5- and 10-year follow-up. However, all patients displayed values below 3 μg/L. The cumulative 10-year survival was 98% in both groups.

CONCLUSION

There were no problems with the new coating system. No relevant increase in metal ion serum levels were measured. A slight increase in cobalt serum levels in the standard TKA was noted, thus not reaching critical values. The new coating system demonstrated equally good PROs as the standard TKA. Excellent implant survival was observed in both groups.

LEVEL OF EVIDENCE

I.

Metal Allergy: State-of-the-Art Mechanisms, Biomarkers, Hypersensitivity to Implants

Metal allergy is mainly an environmental disorder which can cause allergic contact dermatitis. Environmental metal exposures include jewelry, everyday metal items, mobile phones, leather, metal-rich food and implants, including stents or anchors. While consumer exposure is liable for the majority of metal hypersensitivity cases, the significance of occupational exposure to metals remains relevant. Although the most common metal allergens are nickel, chromium, and cobalt; however, lately, gold, palladium, titanium, and some others have also attracted attention. This review highlights advances in metal allergy mechanisms, biomarkers for potential patients' stratification as well as biological treatments. The most recent evidence of human exposure to metal for risk assessment is discussed, as well as the relationship between the occurrence of metal hypersensitivity and implanted devices, including non-characteristic symptoms. The latest data on the diagnosis of metal hypersensitivity are also reported.

Metal allergy in primary and revision total knee arthroplasty : a scoping review and evidence-based practical approach

Aims

Metal allergy in knee arthroplasty patients is a controversial topic. We aimed to conduct a scoping review to clarify the management of metal allergy in primary and revision total knee arthroplasty (TKA).

Methods

Studies were identified by searching electronic databases: Cochrane Central Register of Controlled Trials, Ovid MEDLINE, and Embase, from their inception to November 2020, for studies evaluating TKA patients with metal hypersensitivity/allergy. All studies reporting on diagnosing or managing metal hypersensitivity in TKA were included. Data were extracted and summarized based on study design, study population, interventions and outcomes. A practical guide is then formulated based on the available evidence.

Results

We included 38 heterogeneous studies (two randomized controlled trials, six comparative studies, 19 case series, and 11 case reports). The evidence indicates that metal hypersensitivity is a rare complication with some histopathological features leading to pain and dissatisfaction with no reliable screening tests preoperatively. Hypoallergenic implants are viable alternatives for patients with self-reported/confirmed metal hypersensitivity if declared preoperatively; however, concerns remain over their long-term outcomes with ceramic implants outperforming titanium nitride-coated implants and informed consent is paramount. For patients presenting with painful TKA, metal hypersensitivity is a diagnosis of exclusion where patch skin testing, lymphocyte transformation test, and synovial biopsies are useful adjuncts before revision surgery is undertaken to hypoallergenic implants with shared decision-making and informed consent.

Conclusion

Using the limited available evidence in the literature, we provide a practical approach to metal hypersensitivity in TKA patients. Future national/registry-based studies are needed to identify the scale of metal hypersensitivity, agreed diagnostic criteria, and management strategies.

Cite this article: Bone Jt Open 2021;2(10):785–795.

Self-reported metal hypersensitivity in patients undergoing unicondylar knee arthroplasty

OBJECTIVES

There is ongoing discussion about arthroplasty surgery of patients with metal hypersensitivity. The aim of this study was to compare the functional outcomes and eosinophil counts of unicondylar knee arthroplasty (UKA) patients with and without a history of metal hypersensitivity.

METHODS

A retrospective review was made of the medical records of 148 extremities of 140 consecutive patients who underwent primary UKA between January 2016 and December 2017. The patients who met the inclusion criteria were screened for history of metal hypersensitivity using a questionnaire. The functional outcomes of patients and eosinophil levels were evaluated immediately before and at 6 weeks after surgery.

RESULTS

The mean follow-up period was 37 months (range, 18-48 months). Of the total 128 patients, 13 (10.2%) reported a history of metal hypersensitivity before the operation. There was no statistically significant difference between patients with or without a history of metal hypersensitivity in respect of the functional outcomes or eosinophil counts (p > 0.05).

CONCLUSIONS

The results of this study showed that the functional outcomes of patients who underwent UKA using a standard alloy did not change between the groups who reported having or not having a history of metal hypersensitivity. Although the study also showed that the eosinophil counts decreased after surgery compared to the preoperative counts, there was no statistical relationship between the eosinophil count and functional outcomes or metal hypersensitivity history.