Patient-Reported Metal Allergy: A Risk Factor for Poor Outcomes After Total Joint Arthroplasty?

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.

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

INTRODUCTION

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.

MATERIAL AND METHODS

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.

RESULTS

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).

CONCLUSION

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.

Causes and risk factors for same-day discharge failure after total hip and knee arthroplasty: a meta-analysis

In recent decades, the trend toward early same-day discharge (SDD) after surgery has dramatically increased. Efforts to develop adequate risk stratification tools to guide decision-making regarding SDD versus prolonged hospitalization after total hip arthroplasty (THA) remain largely incomplete. The purpose of this report is to identify the most frequent causes and risk factors associated with SDD failure in patients undergoing THA and total knee arthroplasty (TKA). A systematic search following PRISMA guidelines of four bibliographic databases was conducted for comparative studies between patients who were successfully discharged on the same day and those who failed. Outcomes of interests were causes and risk factors associated with same-day discharge failure. Odds ratios (OR) were calculated for dichotomous variables, whereas mean differences (MD) were calculated for continuous variables. Meta-analysis was performed using RevMan software. Random effects were used if there was evidence of heterogeneity. Eight studies with 3492 patients were included. The most common cause of SDD failure was orthostatic hypotension, followed by inadequate physical condition, nausea/vomiting, pain, and urinary retention. Female sex was a risk factor for failure (OR 0.77, 95% CI 0.63-0.93), especially in the THA subgroup. ASA score IV (OR 0.33, 95% CI 0.14-0.76) and III (OR 0.72, 95% CI 0.52-0.99) were risk factors, as were having > 2 allergies and smoking patients. General anesthesia increased failure risk (OR 0.58, 95% CI 0.42-0.80), while spinal anesthesia was protective (OR 1.62, 95% CI 1.17-2.24). The direct anterior and posterior approaches showed no significant differences. In conclusion, orthostatic hypotension was the primary cause of SDD failure. Risk factors identified for SDD failure in orthopedic surgery include female sex, ASA III and IV classifications, a higher number of allergies, smoking patients and the use of general anesthesia. These factors can be addressed to enhance SDD outcomes.

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.

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.

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

Background

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.

Methods

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).

Results

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.

Conclusions

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.

Beneficial effect of a zirconium-nitride-coated implant in total knee arthroplasty revision for suspected metal hypersensitivity

INTRODUCTION

Revision of total knee arthroplasty (rTKA) for suspicion of metal hypersensitivity (MHS) may require hypoallergenic implants. Results for coated implants have not been reported. The aim of the present study was to assess short-term results and survival of rTKA for MHS using a multilayer implant coating.

HYPOTHESIS

Multilayer implant coating improves functional results in rTKA, with survival comparable to primary coated implants.

MATERIAL AND METHODS

A single-center retrospective observational study included 28 patients (30 knees) undergoing rTKA for MHS using a coated implant between May 2011 and November 2016. Exclusion criteria comprised implant malpositioning and history of infection in the affected knee. Clinical and radiological results were assessed on the International Knee Society (IKS) and SF-36 functional scores and Ewald radiological score. Survival was calculated on Kaplan-Meier estimation.

RESULTS

Mean follow-up was 3.8 years. Mean IKS score increased by 40.2 points (40%) [range, 28.1-52.3] (p<0.05). Mean range of motion increased by 17° [range, 9.5-24.5°] (p<0.05). Mean physical and mental SF-36 components were respectively 44.7 and 46.1. Survivorship was 93%.

DISCUSSION

There was significant functional improvement after rTKA for MHS. There were no short-term complications related to the zirconium nitrate coating. However, studies with longer follow-up will be needed for confirmation.

LEVEL OF EVIDENCE

IV; retrospective study.

James A. Rand Young Investigator's Award: Questioning the "Nickel Free" Total Knee Arthroplasty

BACKGROUND

A study was performed to measure metal ions present in the knee joint after performing a total knee arthroplasty (TKA) with standard cobalt chromium (CoCr) components as well as with "nickel-free" oxidized zirconium femoral and titanium tibial (OxZr/Ti) components.

METHODS

Knee joint fluid was collected prior to arthrotomy, and on postoperative day one to determine the amount of metal debris generated when performing a TKA with standard instrumentation from consecutive cases with CoCr components (n = 24) and OxZr/Ti components (n = 16).

RESULTS

CoCr implant patients had statistically higher levels of nickel (Ni) (29.7%, P = .033), cobalt (Co), (1,100.7%, P < .0001) and chromium (Cr) (118.9%, P < .0001) postoperatively. The cutting blocks and sawblades do not contain Co, which therefore must have come from the components. The metal ions generated from the sawblades and cutting blocks, therefore, could be discerned from the OxZr/Ti whose components don't contain Co, Cr, or Ni. The OxZr patients had significantly higher Cr (9.5×, P < .001) and Ni (5.1×, P < .001) post-TKA vs pre-TKA; Co levels were not significantly different as expected with the absence of Co in the components (P = .60). The Ni levels generated in performing an Oxinium TKA was 3.3 times higher than when performing a CoCr TKA (1.37 vs. 41 ppb, P < .001).

CONCLUSIONS

The substantial degree of Ni generation resulting from performing a hypoallergenic "nickel-free" TKA calls into questions the rationale of utilizing more expensive lower Ni components on the basis of known or suspected Ni or Cr allergy.

Clinical Results of Revision TKA in Patients With Presumed Metal and Cement Allergy

BACKGROUND

Metal and cement allergy affects a small subset of patients, causing severe pain and often systemic reaction after total knee arthroplasty (TKA). Revision with ceramic-surfaced femoral components has been reported to resolve these symptoms of metal allergy, but no solution currently is available for patients with allergies to metal and bone cement.

METHODS

Five patients (5 knees) with documented metal allergy were revised with custom porous-coated ceramic femoral components (Magnesia-stabilized Zirconia) from January 2007 to January 2013. An additional 23 patients (23 knees) met inclusion criteria from 2007 to 2015, but because the ceramic implant was unavailable, they underwent different treatment based on their underlying allergy to metal, cement, or both. Inclusion criteria included the history of clinically documented severe metal allergy, severe pain, swelling, and effusion >1 year after TKA, negative workup for infection, loosening, and ligament imbalance. Knee Society scores were compared for each cohort.

RESULTS

Mean Knee Society scores for all 5 patients revised with custom cementless ceramic femoral components improved significantly for objective score (preoperative, 39 ± 5; most recent visit, 90 ± 2) and function score (preoperative, 33 ± 8; most recent visit 93 ± 4) (P < .0001). The 12 knees revised with off-the-shelf cemented ceramic-coated femoral components had similar results. The 7 unrevised knees (including 4 knees with allergy to metal and bone cement) and the 4 knees revised with standard CoCr femoral components did not improve and worsened over time.

CONCLUSION

Symptoms resolved in the 5 patients revised with custom ceramic implants and in the 12 patients revised with ceramic-coated components, but did not improve in the patients unrevised or revised with CoCr femoral components. Symptoms presumed to be associated with metal or cement allergy improve with the use of ceramic femoral surfaces, but patients who are allergic both to metals and bone cement would be candidates only for porous-coated ceramic implants fixed without bone cement.

[The use of knee prostheses with a hypoallergenic coating is safe in the medium term : A randomized controlled study]

BACKGROUND

In Germany, patients with contact allergy to implant components usually receive coated joint arthroplasties. Whether the treatment using these hypoallergenic implants achieves comparable results to standard treatment with implants consisting of cobalt-chromium alloy (CoCr) implants is controversially discussed internationally and has rarely been investigated in the mid-term.

OBJECTIVES

Are there differences in blood metal ion concentrations, knee function, and patient-reported outcomes (PROM) between coated and standard implants?

MATERIAL AND METHODS

118 patients were randomized to receive either a coated or a standard implant. Knee function as well as patient-reported outcome measures were assessed. Metal ion concentrations in blood samples were additionally determined for chromium, cobalt, molybdenum, and nickel, preoperatively, one and five years after surgery.

RESULTS

After five years, it was possible to analyse the results of 97 patients. In metal ion concentrations, as well as PRO, consistently good results were seen, without any difference between the groups. While in 13 patients there was an increase in chromium concentration above 2 µg/l one year after surgery, there was no measured value above 1 µg/l after five years.

CONCLUSION

In our study, similar mid-term results were detected for coated (TiNiN) and standard (CoCr)TKA. With respect to metal ion concentrations and PRO there are no disadvantages in using coated TKA.

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.

Suspected Metal Allergy and Femoral Loosening After Total Knee Arthroplasty: A Diagnostic Dilemma

Metal sensitivity is increasingly prevalent and is associated with negative outcomes after total knee arthroplasty (TKA). Currently, there is no consensus on diagnostic criteria for TKA failure from immune reaction. We present a patient who had pain and aseptic effusion 2 years after TKA. Radiographs were concerning femoral loosening. Lymphocyte transformation testing showed nickel sensitivity. During revision surgery, the femoral component was loose. The histologic aseptic lymphocyte-dominated vasculitis-associated lesion score was 4 with elevated CD4+ lymphocytes, consistent with sensitization. Nickel-free revision implants were used. One year after surgery, the patient is symptom-free. This case has features suggestive of an immune reaction, with femoral loosening, and is illustrative of the diagnostic dilemma. Using a hypoallergenic knee eliminates future concern for nickel sensitivity.

Titanium Niobium Nitride Mobile-Bearing Unicompartmental Knee Arthroplasty Results in Good to Excellent Clinical and Radiographic Outcomes in Metal Allergy Patients With Medial Knee Osteoarthritis

BACKGROUND

The main purpose of the present study was to analyze the clinical and radiological outcomes of patients with positive skin patch tests who underwent medial mobile-bearing titanium niobium nitride unicompartmental knee arthroplasty (UKA) during a mid-term follow-up.

METHODS

Thirty-seven patients with positive skin patch tests were included in this prospective study. The clinical evaluation consisted of Oxford Knee Score and Knee Society Score (KSS) reports. Each patient was clinically evaluated the day before surgery (T₀) as well as at T₁ (11.9 ± 1.3 months) and during the final follow-up T₂ (67.2 ± 19.1 months). The positioning of the UKA was evaluated during the final follow-up using standardized radiographs (T₂: 67.2 ± 19.1 months).

RESULTS

Oxford and KSS ranged from a respective mean preoperative value of 23.0 ± 2.7 and 51.5 ± 5.0 to 42.1 ± 1.7 and 87.6 ± 2.2, respectively, at T₁ (P < .001) and to the final values of 45.0 ± 1.9 and 91.9 ± 3.4, respectively, at T₂ (P < .001 both vs T₁ and T₂). At T₂, the mean femoral angle was 7.0° ± 4.5°, mean tibial angle was 3.0° ± 2.1°, and mean tibial slope was 5.1° ± 3.2°. A significant difference was found between KSS and Oxford with ANOVA for repeated measures over time (P < .001). The Oxford and KSS scores showed significant improvements during each follow-up. No complications were found, and not a single patient required a revision surgery during the follow-up period.

CONCLUSION

The hypoallergenic titanium niobium nitride mobile-bearing UKA showed comparable results to standard CoCr UKA regardless of the gender, age, BMI, and implant size of metal allergy patients with medial knee osteoarthritis. Careful patient selection processes and accurate medical histories played key roles in the choice of hypersensitivity-friendly implants.

Early Failures of Total Knee Patients with Nickel Allergies Secondary to Carbon Fiber Debris

Aim:

Currently, there are not many studies on the long-term outcomes of the specific implants used in patients with metal hypersensitivities. The purpose of this study is to report a significant number of TKA revision failures with the CFR-PEEK prosthetic knee implant with an anatomic hinge.

Background:

Patients can experience multiple issues following a primary Total Knee Arthroplasty (TKA). A growing body of research is finding a correlation between primary TKA failure and metal hypersensitivity, most commonly with nickel and cobalt. Because of this, knee prosthetics are being made from hypoallergenic metals, such as zirconium nitride (ZrN), to minimize the number of failures due to metal allergy. Given the relatively new development of the hypoallergenic prostheses, there is sparse data about their overall success.

Objective:

The purpose of this study is to report a significant number of TKA revision failures with the CFR-PEEK prosthetic knee implant with an anatomic hinge.

Methods:

In this study, we analyzed the sequelae of 84 patients between May 2015 to June 2020 who received a total knee revision due to a failed primary TKA with metal hypersensitivity. These patients were revised with the rotating anatomic hinge knee system, which consisted of Carbon Fiber Reinforced Poly-Ether-Ether-Ketone (CFR-PEEK implant) coated with a ZrN, Zirconium, and Chrome Nitride multi-layer surface coating with 30% polyacrylonitrile fiber content. The patients requiring an additional revision operation presented with increasing pain that showed evidence of osteolysis on plain radiographs, CT imaging, positive indium labeled WBC scans and increased uptake on bone scan. Intraoperatively, an open incisional biopsy of the surgical bed was obtained, followed by radical debridement and implantation of porex knee prosthesis. In addition, intraoperative findings included black debris that grossly stained the surrounding synovial tissue black, indicative of wear and debris from carbon fiber bearings and the anatomic hinge. Histology of the intraoperative biopsy showed the accumulation of black debris in the histiocyte, fibrosis, and perivascular cuffing of lymphocytes and multinucleated giant cells stained with black debris.

Results:

Of the 84 patients, 22 failed, requiring an additional revision procedure, equating to a 26 percent failure rate of the CFR-PEEK implant, averaging 25 months to failure.

Conclusion:

This study was meant to report the extremely high failure rate of the anatomic hinge secondary to carbon fiber debris. Perhaps carbon fiber-laden implants are not as good an option for total knee revision prosthesis because of the high failure rate compared to those with polyethylene in their hinge mechanism.

Decrease of Quality of Life, Functional Assessment and Associated Psychological Distress in Patients with Hypoallergenic Total Knee Arthroplasty

Total knee arthroplasty (TKA) is the final treatment for knee osteoarthritis, and 15-30% of patients show little or no improvement. This high percentage is related to aspects of the surgical technique, the selected implant, and specific patient characteristics. The aim of this study was to analyze whether there are differences in quality of life (QoL) and functional capacity among patients undergoing TKA with conventional implants compared to those treated with hypoallergenic oxinium implants. A pragmatic clinical study was carried out that included patients who underwent TKA between January 2013 and December 2015. During this period, 245 knees in 228 patients were treated. Eleven patients were excluded, leaving a sample of 161 conventionally treated knees, 72 knees treated with hypoallergenic implants, and one patient who received both implant types. In all patients, QoL and functional capacity were measured with the WOMAC index, the SF-12 questionnaire, and the Euro-Qol-5D L-VAS. We also assessed the psychological distress of each patient and related the findings to the functional results. The differences in QoL were tested using ANCOVA and propensity score matching (PSM) models adjusted for sex, age, weight, psychiatric history and associated complications. Patients who underwent TKA using conventional prostheses had significantly better scores on the total WOMAC index and in the pain domain (p < 0.05) than those who received hypoallergenic prostheses, but no significant differences were observed for the other domains in the ANCOVA. In contrast, with the PSM, we also found statistically significant differences in the difficulty domain of the WOMAC. Significant differences were found for the SF-12 mental health questionnaire results (p = 0.038), but the same did not occur for the physical health domain in the ANCOVA and PSM. We also found statistically significant differences in the Euro-Qol-5D index results (p = 0.041), but not in the VAS scale scores for the same questionnaire in the ANCOVA, and we did not find significant differences in either with the PSM. Patients with metal allergies and those who present psychological distress had WOMAC, SF-12, and Euro-Qol-5D results that were statistically significantly worse than those of patients who received conventional implants. Patients who underwent hypoallergic TKA had lower scores on the QoL and functional capacity scales than patients who received conventional Cr-Co implants. Additionally, patients with psychological distress had worse results on the questionnaires, and those with a metal allergy had even lower scores; the differences were statistically significant.

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.

Prevalence of metal hypersensitivity in patients with shoulder pathologies

BACKGROUND

To date, medical history and dedicated questionnaires are the fastest and easiest way to assess risks of joint metal hypersensitivity. No published studies determined the overall prevalence of hypersensitivity to metals in patients with shoulder pathologies. The purpose of this study was therefore to estimate the prevalence of metal hypersensitivity reported by patients with shoulder pathologies, and to identify patients at risk of joint metal hypersensitivity based on a dedicated questionnaire.

METHODS

The authors prospectively asked all adult patients consulting for shoulder pathologies between September 2018 and February 2019 at 10 centers to fill in a form. The main outcome was "reported hypersensitivity to metals," comprising belt buckles, coins, earrings, fancy jewelry, keys, leather, metallic buttons, piercings, spectacles, watch bracelets, or zips.

RESULTS

A total of 3217 patients agreed to fill in the survey, aged 55 ± 16 (range, 18-101) with equal proportions of men (51%) and women (49%), and a majority of patients consulting for cuff pathology (55%). A total of 891 (28%) patients had professions considered at risk for metal hypersensitivity. The most frequently reported metal hypersensitivities were fancy jewelry (15%), earrings (13%), and watch bracelets (9%). A total of 629 (20%) patients, of which the vast majority were women, reported hypersensitivity to 1 or more metals.

CONCLUSIONS

This survey of 3217 patients identified 20% who reported metal hypersensitivities, though only 2.2% had done patch tests. Matching profiles of those with positive patch tests to those with no patch tests revealed that 9.4% of the total cohort had similar sex and self-reported metal hypersensitivities. Factors associated with a positive patch test were female sex, self-reported cutaneous allergy, and self-reported metal hypersensitivity. The clinical applicability of these estimates remains uncertain as there is insufficient evidence that allergy to metal implants can be predicted by questionnaires or patch tests.

The effect of patient-reported metal allergies on the outcomes of shoulder arthroplasty

BACKGROUND

Although literature exists regarding hip and knee arthroplasty outcomes in patients with skin allergy to metals, there is minimal information about skin allergy implications on shoulder arthroplasty outcomes. The purpose of this study was to determine the results, complications, and failure rate among patients with a self-reported metal allergy undergoing shoulder arthroplasty.

METHODS

Fifty-two shoulder arthroplasties were performed at our Institution in 43 patients with self-reported metal allergies. Forty primary and 12 revision shoulder arthroplasties were performed using anatomic (30) and reverse (22) components. Retrospective chart review was performed to determine metal allergy history, implant composition, pain, motion, and complications. Radiographs were reviewed to determine mechanical failure rates. Average follow-up time was 65 months.

RESULTS

Allergies reported included nickel (37), cobalt chrome (4), copper (2), zinc (1), titanium (1), gold (1), and nonspecific metal allergy (8); 8 patients reported multiple metal allergies. All components implanted in patients with nickel allergies contained nickel. At most recent follow-up, pain was rated as none or mild in 88% of shoulders. Active elevation improved from 80° to 141° and external rotation from 24° to 52°. Two revisions were performed for glenoid loosening (3.8%); both were revision cases with substantial glenoid bone loss. One patient with mild pain had a radiographically loose glenoid component 12 years after anatomic shoulder arthroplasty.

CONCLUSION

Results from this study suggest that shoulder arthroplasty in patients with self-reported metal allergy provides satisfactory pain relief and improved range of motion with low revision rates.

Incidence of Metal Hypersensitivity in Orthopedic Surgical Patients Who Self-Report Hypersensitivity History

INTRODUCTION

Metallic implants are integral to the practice of orthopedic surgery. Delayed-onset T-cell-mediated metal hypersensitivity (diagnosed by patch testing) is reported in 10% to 17% of the general population. Inconclusive evidence exists about the role of metal hypersensitivity in persistently painful or aseptic loosening of arthroplasties. Literature suggests that preoperative patch testing may influence surgical practice.

OBJECTIVE

To determine the incidence of metal hypersensitivity in orthopedic surgical patients who self-report hypersensitivity and to characterize which metals are most commonly implicated.

METHODS

A retrospective chart review of patients from a single surgeon's practice was conducted during a 1-year period. All patients were questioned about metal hypersensitivity history; all patients who responded affirmatively were sent for patch testing for specific metals.

RESULTS

Only 41 (4.9%) of 840 patients self-reported any metal hypersensitivity. Of these, 34 (83%) were patch-test positive to 1 or more metals. There were 27 whose test results were positive for nickel, 4 each to cobalt or gold thiosulfate, and 1 each to tin or titanium. Seven patients had positive results to multiple metals, all of whom were also nickel hypersensitive. Six patients had metal orthopedic implants before patch testing, and 4 (67%) tested positively to a metal in their implant.

CONCLUSION

Metal hypersensitivity can be concerning for treating surgeons and patients. Greater awareness of a history to hypersensitivity may prevent patient exposure to implants containing metals that may cause hypersensitivity. Non-metal-containing or nonreactive metal implants are an option for patients in whom metal hypersensitivity is suspected or confirmed.

Surgical explantation of atrial septal closure devices for refractory nickel allergy symptoms

OBJECTIVES

Systemic allergic reactions to nickel alloys in percutaneous atrial septal defect occlusion devices have a poorly defined natural history. We describe our experience of surgical removal of the offending device in a series of patients with nickel allergy and refractory symptoms.

METHODS

Patients with atrial septal defect device explants for nickel allergy were reviewed. Administered questionnaires focused on symptoms, quality of life, and satisfaction along with the 36-Item Short Form Health Survey to measure physical and mental health postsurgery.

RESULTS

Atrial septal defect devices were removed for nickel allergy in 58 patients during the past 10 years. The median age was 42 years (range, 24-71 years) and 95% were women. Explantation occurred at a median of 8 years (range, 6 months-18 years) after insertion. Symptoms included fatigue (82%), chest pain (78%), headache (73%), and palpitation (58%). Surveys were available for 45 patients: 58% rated their quality of life as poor and 69% were not at all satisfied with their device. Postexplant, all patients reported improvement in their symptoms, with 18 patients (42%) noting complete resolution. In 12 patients prospectively studied, the preoperative scores in physical and mental health domains were lower than the validation group, indicating significant disability. Similarly, there was marked improvement in each domain postremoval.

CONCLUSIONS

Patients with nickel allergy and severe refractory symptoms after atrial septal defect device implantation experience profound resolution of symptoms and improved quality of life after removal. Nickel allergy should be considered before device insertion, and a low threshold should exist for surgical removal for refractory symptoms.

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

The impact of self-reported metal allergy (SRMA) in total knee arthroplasty (TKA) remains controversial. In the absence of objective tests, SRMA is often used as a screening tool for implant selection. The objective of this study was to determine the effect of SRMA on early outcomes after TKA. Between 2010 and 2014, 168 patients with SRMA underwent TKA; 150 (89%) received nickel-free implants, and 18 (11%) received cobalt-chrome implants that contained nickel. Mean age was 67 years, and 95% were female. A cohort of 858 TKA patients (mean age, 68 years) without SRMA matched by sex served as the control group. Outcomes included Knee Society Score (function [KSS-F] and knee [KSS-K]), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, knee flexion, further surgery, and complications. No differences were seen in KSS-F and KSS-K between patients with and without SRMA. The mean WOMAC pain scores were 89.1 for patients with SRMA and 85.2 for patients without SRMA (P=.030). Stiffness and physical function scores were similar. Knee flexion was similar. No differences were found between nickel-free and cobalt-chrome SRMA groups. Patients with SRMA and those without demonstrated similar early functional outcomes. Patients with SRMA who received standard cobalt-chrome implants had no significant difference in functional outcomes compared with patients with nickel-free implants. Better identifiers of patients at risk for adverse events due to implant material are needed. [Orthopedics. 2019; 42(6):330-334.].

Evaluation of the Painful Total Knee Arthroplasty

Total knee arthroplasty (TKA) has been associated with notable improvements in health-related quality of life of patients with end-stage knee arthritis. Although most patients experience substantial symptomatic relief after TKA, up to 19% of patients are unsatisfied with their outcome. With the dramatic, projected increase in the number of TKAs performed annually, it is crucial to appreciate the various modes of failure associated with this procedure. A comprehensive understanding of the symptomatology and thorough clinical examination aid in identifying the etiology of ongoing knee pain. Ancillary testing including conventional laboratory analyses, imaging studies, and diagnostic injections supplement a thorough history and physical examination. In addition, novel laboratory markers, RNA/DNA-based tests, and novel imaging modalities are emerging as beneficial tools in evaluating patients with a painful TKA. A well-structured, algorithmic approach in the management of these patients is essential in correctly diagnosing the patient and optimizing clinical outcomes.

Tobacco Smoking Independently Predicts Lower Patient-Reported Outcomes: New Insights on a Forgotten Epidemic

BACKGROUND

Although smoking is a well-accepted risk factor for surgical complications, the effect of smoking on patient-reported outcomes (PROs) has not been previously investigated. Prompted by an increasingly value-conscious healthcare environment, the purpose of this study is to investigate the association between smoking and PROs in total joint arthroplasty (TJA).

METHODS

A retrospective review of 713 primary total hip and knee replacements was performed. Two cohorts were compared: (1) current smokers and (2) previous/never smokers at the time of TJA. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Short Form-12 Physical Composite Summary (SF-12 PCS) and Short Form-12 Mental Composite Summary were assessed preoperatively and again at 6 and 12 months postoperatively. The primary outcomes were the net changes and absolute outcome scores at final follow-up. Postoperative patient satisfaction was also assessed as a secondary outcome. Linear mixed-effects regression analysis was performed.

RESULTS

There were significant demographic and preoperative health disparities as measured by PROs among smokers. After adjusting for baseline differences, smokers achieved significantly lower improvements in WOMAC (P = .002) and SF-12 PCS (P = .03) compared to nonsmokers. For each unit increase in packs per day smoked, the WOMAC scores increased (worsened) by 7.7 points (P = .003) and SF-12 PCS decreased by 4.8 points (P = .001). At final follow up, nonsmokers had significantly better absolute scores for all outcomes (except for mental health) and were more likely to be satisfied with surgery (89% vs 82%, P = .052).

CONCLUSION

Tobacco smoking is an independent predictor for lower PROs after TJA and this relationship is dose-dependent. The negative impact of smoking does not appear to be related to impaired psychological health. As we transition to value-based care delivery models, this study provides further evidence that smoking cessation should be strongly recommended as a modifiable risk factor before embarking on elective TJA. Studies are still needed to define the optimal window for smoking cessation.

Corrosion of Al2O3-Ti composites under inflammatory condition in simulated physiological solution

Alumina-titanium composites have shown good mechanical properties which makes them promising for orthopedic applications. The placement of an orthopedic implant involves an invasive procedure which stimulates a localized inflammatory response causing an acidic environment around the implant. This makes the study on corrosion more critical. Therefore, the aim of the present paper was to study the corrosion behavior of the composites with 75 vol% and 50 vol% Ti content (with alumina balance) fabricated by Spark Plasma Sintering under acidic condition representing inflammation and in two elapsed times (1 h and 1-day) using polarization and electrochemical impedance spectroscopy tests. For comparison, the experiments were also conducted in normal physiological solution after 1 h, and pure Ti (100vol%Ti) was fabricated by the same process and analyzed, similarly. Furthermore, behavior of the samples was studied after 48 days of immersion in the acidic and normal solutions using SEM, ATR-FTIR, AFM, and ICP-OES. The results of corrosion tests showed very good passivation behavior of 100vol%Ti and the composite containing 75vol.%Ti. The superiority of the 75vol.%Ti composite in corrosion characteristics in both solutions was also found. Its corrosion resistance was 20.3 MΩcm² under the inflammatory condition after 1-day, which was 39% higher than that of 100vol.%Ti under the same condition. The results of SEM indicated both corroded and mineral deposition zones on all materials' surfaces and the ATR-FTIR results revealed additional adsorbed bands related to water adsorption, OH and carbonate groups after immersion. The AFM analysis showed rougher morphology, particularly for 75 vol% Ti where the Rq was increased about 50 nm, and the ICP-OES results indicated 65.87% and 61.94% deposition of solution calcium on 75vol.%Ti and 50vol.%Ti, respectively. The acidic/inflammatory condition influenced the corrosion processes of all materials. Lower pH caused the passivation to occur sooner and the corrosion resistance to be higher.

Are Self-Reported Medication Allergies Associated With Worse Hip Outcome Scores Prior to Hip Arthroscopy?

PURPOSE

To determine if there are significant differences in preoperative patient-reported outcome (PRO) scores in patients with and without self-reported medication allergies undergoing hip arthroscopy.

METHODS

Consecutive subjects undergoing hip arthroscopy for femoroacetabular impingement (FAI) syndrome by a single surgeon were retrospectively reviewed. PROs were collected within 6 weeks of the date of surgery. PROs included International Hip Outcome Tool (iHOT-12), Hip Outcome Score (HOS), and Short-Form (SF-12) scores. Allergies to medications were self-reported preoperatively within 6 weeks of the date of surgery. Patient demographics were recorded. Bivariate correlations and multivariate regression models were calculated to identify associations with baseline hip outcome scores.

RESULTS

Two hundred twelve subjects were analyzed (56% female, mean age 35.1 ± 13.2 years). Seventy-two subjects (34%) self-reported allergies (range 1-10; 41 subjects had 1 allergy; 14 subjects had 2; 8 subjects had 3; 2 subjects had 4; 7 subjects had 5 or more). The most commonly reported allergies included penicillin (18), sulfa (13), and codeine (11). Female gender was significantly correlated with number of allergies (Pearson correlation coefficient, 0.188; P < .001). SF-12 Mental Component Score (MCS) was significantly correlated with HOS-ADL (Pearson correlation coefficient, 0.389; P < .001), HOS-SSS (Pearson correlation coefficient, 0.251; P < .001), and iHOT-12 (Pearson correlation coefficient, 0.385; P < .001). There was no significant correlation between number of allergies and all hip PROs. In all multivariate models, the SF-12 MCS had the strongest association with HOS-ADL, HOS-SSS, and iHOT-12 (P < .001 for all). Allergies were not significantly associated with any hip PROs.

CONCLUSIONS

In patients undergoing hip arthroscopy for FAI syndrome, self-reported medication allergies are not significantly associated with preoperative patient-reported hip outcome scores.

LEVEL OF EVIDENCE

Level III, retrospective comparative case series.

Biological effects of metal degradation in hip arthroplasties

Metals and metal alloys are the most used materials in orthopedic implants. The focus is on total hip arthroplasty (THA) that, though well tolerated, may be associated with local and remote adverse effects in the medium-long term. This review aims to summarize data on the biological consequences of the metal implant degradation that have been attributed predominantly to metal-on-metal (MoM) THA. Local responses to metals consist of a broad clinical spectrum ranging from small asymptomatic tissue lesions to severe destruction of bone and soft tissues, which are designated as metallosis, adverse reactions to metal debris (ARMD), aseptic lymphocytic vasculitis associated lesion (ALVAL), and pseudotumors. In addition, the dissemination of metal particles and ions throughout the body has been associated with systemic adverse effects, including organ toxicity, cancerogenesis, teratogenicity, and immunotoxicity. As proved by the multitude of studies in this field, metal degradation may increase safety issues associated with THA, especially with MoM hip systems. Data collection regarding local, systemic and long-term effects plays an essential role to better define any safety risks and to generate scientifically based recommendations.

The [Mo₆Cl14]2- Cluster is Biologically Secure and Has Anti-Rotavirus Activity In Vitro

The molybdenum cluster [Mo₆Cl14]2- is a fluorescent component with potential for use in cell labelling and pharmacology. Biological safety and antiviral properties of the cluster are as yet unknown. Here, we show the effect of acute exposition of human cells and red blood cells to the molybdenum cluster and its interaction with proteins and antiviral activity in vitro. We measured cell viability of HepG2 and EA.hy926 cell lines exposed to increasing concentrations of the cluster (0.1 to 250 µM), by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. Hemolysis and morphological alterations of red blood cells, obtained from healthy donors, exposed to the cluster (10 to 200 µM) at 37 °C were analyzed. Furthermore, quenching of tryptophan residues of albumin was performed. Finally, plaque formation by rotavirus SA11 in MA104 cells treated with the cluster (100 to 300 µM) were analyzed. We found that all doses of the cluster showed similar cell viability, hemolysis, and morphology values, compared to control. Quenching of tryptophan residues of albumin suggests a protein-cluster complex formation. Finally, the cluster showed antiviral activity at 300 µM. These results indicate that the cluster [Mo₆Cl14]2- could be intravenously administered in animals at therapeutic doses for further in vivo studies and might be studied as an antiviral agent.

Metal Hypersensitivity Reactions to Orthopedic Implants

Total hip and knee replacement surgery using metal alloy devices is common. Type IV allergic reactions to these implants occur, though infrequently. While uncommon, peri-implant metal allergic reactions may cause significant morbidity for the affected individual-including aseptic loosening, pseudotumor formation and frank device failure. It is challenging to predict who will have these reactions, even in those with established pre-implant metal allergy. At this time, the scientific literature clearly supports few conclusions. Despite this, we believe several conclusions can be made: routine pre-implant testing in asymptomatic individuals is not indicated; listen to patient's concerns about metal allergy if the concern arises; patch testing is probably the best pre- and post-implant screening test; post-implantation testing is controversial and even positive LTT or patch test does not definitively diagnose morbidity from a metal allergy; and complete recovery following revision placement of an immunologically inert device is diagnostic. More research is needed to scientifically approach this issue.

Shoulder Arthroplasty Outcomes in Patients With Multiple Reported Drug Allergies: Does Number of Drug Allergies Have an Effect on Outcome?

Background:

The presence of multiple allergies has been correlated with worse outcomes for patients undergoing hip and knee arthroplasty, but the effect of allergies has not yet been elucidated with respect to shoulder arthroplasty.

Purpose/Hypothesis:

The purpose of this study is to identify any discrepancies in shoulder arthroplasty outcomes with respect to reported drug allergies. We hypothesized that patients with multiple drug allergies would have inferior outcomes.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Included in the analysis were a single surgeon’s cases between 2009 and 2014 of primary total shoulder arthroplasty with a minimum of 180 days of follow-up. Cases with fracture as the indication were excluded. Preoperative and postoperative metrics included visual analog scale (VAS) for pain, forward flexion range of motion, and Simple Shoulder Test (SST) results, and postoperative patient satisfaction scores were also collected. Chi-square and 1-way analysis of variance with Tukey post hoc analyses were performed when appropriate.

Results:

A total of 98 patients were included (no allergies, n = 51; single allergy, n = 21; multiple allergies, n = 26). The proportion of females was greater with increasing number of allergies (no allergies, 31%; single allergies, 47%; multiple allergies, 88%; Pearson χ² = 22.5; P < .0001). Both preoperatively and postoperatively, no difference was found between cohorts with respect to SST score, VAS score, or forward flexion. There was also no difference in postoperative satisfaction between cohorts. No difference between cohorts was identified when comparing the pre- to postoperative change in SST scores, VAS scores, or forward flexion.

Conclusion:

The presence of single or multiple allergies is not correlated with worse outcomes after primary anatomic total shoulder arthroplasty.