Multiple environmental antigens may trigger autoimmunity in psoriasis through T-cell receptor polyspecificity.

Introduction: Psoriasis is a T-cell mediated autoimmune skin disease. HLA-C*06:02 is the main psoriasis-specific risk gene. Using a Vα3S1/Vß13S1 T-cell receptor (TCR) from a lesional psoriatic CD8+ T-cell clone we had discovered that, as an underlying pathomechanism, HLA-C*06:02 mediates an autoimmune response against melanocytes in psoriasis, and we had identified an epitope from ADAMTS-like protein 5 (ADAMTSL5) as a melanocyte autoantigen. The conditions activating the psoriatic autoimmune response in genetically predisposed individuals throughout life remain incompletely understood. Here, we aimed to identify environmental antigens that might trigger autoimmunity in psoriasis because of TCR polyspecificity. Methods: We screened databases with the peptide recognition motif of the Vα3S1/Vß13S1 TCR for environmental proteins containing peptides activating this TCR. We investigated the immunogenicity of these peptides for psoriasis patients and healthy controls by lymphocyte stimulation experiments and peptide-loaded HLA-C*06:02 tetramers. Results: We identified peptides from wheat, Saccharomyces cerevisiae, microbiota, tobacco, and pathogens that activated both the Vα3S1/Vß13S1 TCR and CD8+ T cells from psoriasis patients. Using fluorescent HLA-C*06:02 tetramers loaded with ADAMTSL5 or wheat peptides, we find that the same CD8+ T cells may recognize both autoantigen and environmental antigens. A wheat-free diet could alleviate psoriasis in several patients. Discussion: Our results show that due to TCR polyspecificity, several environmental antigens corresponding to previously suspected psoriasis risk conditions converge in the reactivity of a pathogenic psoriatic TCR and might thus be able to stimulate the psoriatic autoimmune response against melanocytes. Avoiding the corresponding environmental risk factors could contribute to the management of psoriasis.

No difference in patient reported outcome and inflammatory response after coated and uncoated total knee arthroplasty - a randomized controlled study.

BACKGROUND: Allergies against implant materials are still not fully understood. Despite controversies about its relevance, some patients need treatment with hypoallergenic implants. This study compared coated and standard total knee arthroplasty (TKA) regarding inflammatory response and patient-reported outcome measures (PROMs). METHODS: 76 patients without self-reported allergies against implant materials were included in a RCT and received a coated or standard TKA of the same cemented posterior-stabilized knee system. 73 patients completed the 3-year follow-up. Two patients died and there was one revision surgery. Serum levels of cytokines with a possible role in implant allergy were measured in patient`s serum (IL-1beta, IL-5, IL-6, IL-8, IL-10, IFN γ, TNF α) prior to, one and three years after surgery. Furthermore, PROMs including knee function (Oxford Knee Score, Knee Society Score) and health-related quality of life (QoL, EuroQuol questionnaire) were assessed. Additionally, 8 patients with patch-test proven skin allergy against implant materials who received the coated implant were assessed similarly and compared to a matched-pair group receiving the same implant. RESULTS: There were no differences in function and QoL between the assessed groups at any follow-up. The majority of patients demonstrated no elevation of the measured blood cytokines. Cytokine patterns showed no differences between study groups at any follow-up. The allergy patients demonstrated slower functional improvement and minor differences in cytokine pattern. Yet these results were not significant. There were no differences in the matched-pair analysis. CONCLUSION: We observed no relevant increase in serum cytokine levels in any group. The inflammatory response measured seems limited, even in allergy patients. Furthermore, there were no differences between coated and standard TKA in non-allergy patients in the 3-year Follow-Up period. TRIAL REGISTRATION: The study protocol was registered in the US National Institutes of Health's database ( http://www. CLINICALTRIALS: gov ) registry under NCT03424174 on 03/17/2016.

Increased inflammatory response is associated with less favorable functional results 5 years after total knee arthroplasty.

PURPOSE: Allergy against implant materials is discussed controversially and still not fully understood. Despite these controversies, a relevant number of patients receive hypoallergenic knee implants. The aim of this study was to compare a new coating system with the standard implant in total knee arthroplasty (TKA). Additionally, the influence of proinflammatory cytokines on patient-reported outcome measures (PROMs) was investigated. METHODS: 120 patients without known metal allergy and without previous metal implants were included. The patients were randomized to receive a coated or standard TKA of the same knee system. 105 patients completed the 5 year follow-up. Patient-reported outcome measures (PROMs) including knee function (Oxford Knee Score, OKS), quality of life (SF36) and UCLA activity scale were assessed. Additionally, several cytokines with a possible role in implant allergy were measured in patient`s serum (IL-1beta, IL-5, IL-6, IL-8, IL-10, IP-10, IFN γ, TNF α). Group comparison was performed using Mann-Whitney U test for continuous values and chi-square test for categorical values. RESULTS: There were no differences in PROMs between both groups at any follow-up. The majority of patients demonstrated no elevation of the measured blood cytokines. The blood cytokine pattern after 5 years demonstrated no differences between study groups. There was a significant association between elevated IL-8 values and worse results in the overall OKS (p = 0.041), the OKS function component (p = 0.004), the UCLA activity scale (p = 0.007) and the physical component of SF36 (p = 0.001). CONCLUSION: There were no problems with the new coating during mid-term follow-up and no differences in PROMs between coated and standard TKA. Patients with an increased inflammatory response demonstrated worse functional results, regardless of the implant. LEVEL OF EVIDENCE: I. CLINICAL TRIAL REGISTRATION: The study protocol was registered in the US National Institutes of Health's database ( http://www. CLINICALTRIALS: gov ) registry under NCT00862511.

Contact allergy to the Dexcom G6 glucose monitoring system-Role of 2,2'-methylenebis(6-tert-butyl-4-methylphenol) monoacrylate in the new adhesive.

BACKGROUND: Skin reactions to the glucose monitoring systems Dexcom G5 and G6 have been rare. In 2019, the components of the adhesive were exchanged for better skin fixation. Since then, more and more patients experienced severe skin reactions. A few months ago, 2,2'-methylenebis(6-tert-butyl-4-methylphenol) monoacrylate (MBPA) was identified as a new component in the adhesive of the G6 model. Furthermore, it was suspected that isobornyl acrylate (IBOA) was also a component of the exchanged adhesive. OBJECTIVES: Our objective was to investigate if MBPA plays a major role in the increasing skin problems of patients without a history of IBOA-sensitization. Furthermore, our aim was to examine whether IBOA is contained in the newer model adhesive and may also contribute to allergic contact dermatitis (ACD). PATIENTS AND METHODS: Five patients with a newly occurred ACD caused by the glucose monitoring system Dexcom G6 were investigated. Patch testing including MBPA in three different concentrations, as well as IBOA, were performed. Gas chromatography-mass spectrometry of the newer system Dexcom G6 was carried out. RESULTS: All patients were shown to be sensitized to MBPA, while MBPA 0,5% showed the strongest reaction. On the other hand, IBOA was tested negative. CONCLUSION: In our study group, MBPA was observed to be the triggering allergen of the recently changed adhesive.

Contact sensitization to iron: A potentially underestimated metal allergen and elicitor of complications in patients with metal implants.

BACKGROUND: Little is known about sensitization to iron (Fe) in private, occupational, and medical settings, particulary implantology. OBJECTIVES: To investigate sensitization to metals, particularly to Fe, both in pre-implant individuals with presumed metal allergy and in patients with suspected metal implant allergy. To further characterize Fe-sensitized individuals. METHODS: Analysis of patch test reactions to an Fe (II) sulfate-containing metal series in 183 consecutive patients (41 pre-implant, 142 metal implant bearers). Test readings were on day (D)2, D3, and D6. Evaluation of questionnaire-aided history of metal reactivity patterns and demographics of Fe reactors. RESULTS: Metal reactivity in pre-implant/implant/total group was: to nickel 39%/30%/32%; to cobalt 17%/15%/15%; and to chromium 7%/13%/11%. Co-sensitizations cobalt/nickel (19/58) and cobalt/chromium (11/21) were significant at P < .001; co-sensitizations Fe/nickel (4/10) and chromium/knee arthroplasty (11/73) at P = .03. Ten of 183 (5.5%) reacted to Fe (2 of 41 pre-implant patients, 8 of 142 implant bearers), with 10 reacting only on D6. Fe reactivity was highest in complicated knee arthroplasty (7/73). Further peculiarities of Fe reactors included frequent isolated Fe reactivity (6/10), occupational metal exposure (7/10), previous (par)enteral Fe substitution (6/10). CONCLUSIONS: The 5.5% prevalence of Fe reactions suggests a potentially underestimated role of this metal allergen in general and in implant bearers. The latter also shows a distinct metal sensitization pattern.

Salivary and gingival CXCL8 correlation with periodontal status, periodontal pathogens, and smoking.

OBJECTIVES: Neutrophil granulocytes have been proposed to play a major role in the mediation of periodontitis-associated tissue destruction. Their recruitment and activation are regulated by the chemokine CXCL8. This study aimed to delineate the dependency of CXCL8 expression in gingival crevicular fluid (GCF) and saliva on periodontal status, bacterial infection, and smoking, in patients with periodontitis. METHODS: The study cohort comprised 279 subjects with untreated periodontitis. Probing pocket depth (PPD), gingival recession, bleeding on probing (BOP), plaque index, and bone loss were evaluated. CXCL8 was determined in saliva and GCF using flow cytometry. RESULTS: Considering the entire study sample, CXCL8 levels were correlated with the mean PPD (ρ = 0.131; p = 0.029), severity of periodontitis (ρ = 0.121; p = 0.043), BOP (ρ = 0.204; p = 0.001), and smoking (ρ = -0.219; p < 0.0001) in GCF; and, in whole saliva, with mean PPD (ρ = 0.154; p = 0.010) severity of periodontitis (ρ = 0.140; p = 0.020), gender (ρ = 0.178; p = 0.003), and smoking (ρ = -0.156; p = 0.010). Subgroup analysis among non-smokers revealed significantly higher amounts of CXCL8 in GCF (p = 0.012) and saliva (p = 0.026) comparing subjects with mean PPD ≤3mm and >3mm. CONCLUSION: The current study revealed a strong dependency of CXCL8 expression in GCF on the severity and activity of periodontal disease. Smoking causes a significant reduction in CXCL8 expression in saliva and GCF.

Atopic diseases and airway-related symptoms in Bavarian children before starting primary school: Time trend analyses.

BACKGROUND: After decades of rising prevalence of atopic and airway-related diseases, studies showed stagnating prevalence in western industrialised countries. Objective of this study is to analyse the time trend of prevalence of atopic diseases and airway-related symptoms among Bavarian children before starting primary school. MATERIALS AND METHODS: Five cross-sectional studies from 2004/2005, 2006/2007, 2012/2013, 2014/2015 and 2016/2017 took place in urban and rural regions in Bavaria, Germany. Using standardized parent questionnaires children's atopic diseases and airway-related symptoms were surveyed. Logistic regression analysis (Bonferroni correction: adjusted significance level 0.005) was performed to analyse prevalence of symptoms and diseases from 2004 to 2017 for time trends. RESULTS: The surveys included 27384 Bavarian children aged 5-6 years (52.6% male). In all children the calculated 12-month prevalence of symptoms '≥four episodes of wheeze' (p-value = .0880) and 'rhinoconjunctivitis' (p-value = .3994) reported by parents stagnated, whereas 'wheeze' (p-value<.0001; OR = 0.97; CI = [0.96-0.98]) and 'rhinitis' (p-value = .0007; OR = 0.98; CI = [0.97-0.99]) decreased. In all children the calculated lifetime prevalence of physician-diagnosed 'asthma' (p-value = .5337), and 'hay fever' (p-value = .8206) stagnated, whereas of 'bronchitis' (p-value<.0001; OR = 0.98; CI = [0.98-0.99]) decreased over time. The calculated lifetime prevalence of physician-diagnosed 'atopic eczema' (p-value = .0002; OR = 0.98; CI = [0.97-0.99]) decreased in all children, whereas the calculated 12-month prevalence of the symptom 'itchy rash' increased (p-value = .0033; OR = 1.07; CI = [1.05-1.08]) over time. CONCLUSIONS: Several calculated prevalence of children's atopic diseases and airway-related symptoms reported by parents stagnated in a subgroup of Bavarian children before starting primary school between 2004 and 2017. The time trend of prevalence in 'wheeze', 'rhinitis' and 'bronchitis' decreased. Prevalence of 'atopic eczema' decreased over time, whereas 'itchy rash' increased.

Cross-sectional evaluation of clinical and immunological parameters at partially microgrooved vs machined abutments in humans.

OBJECTIVE: The objective of the present study was to examine the clinical and immunological parameters in samples collected from the peri-implant crevicular fluid (PICF) of machined titanium (M) abutments compared to titanium abutments with a laser-microtextured surface (LMS) on dental implants. MATERIAL AND METHODS: A total of 40 patients with one titanium implant, half of them (n=20) provided with a M abutment (control group) and the other half (n=20) with LMS abutments (test group), were included in the study. Clinical parameters pocket probing depth (PD), full-mouth plaque score (FMPS), radiographic bone loss (RBL), clinical attachment level (CAL), mucosal recession (MR), bleeding on probing (BOP), and width of keratinized mucosa (KM) were evaluated. The peri-implant sulcus fluid was analyzed for cytokines IL-1α, IL-1ß, IL-6, IL-8, and IL-10 via flow cytometry. RESULTS: Clinical evaluation demonstrated no significant difference of PD (mean LMS = 3.50 mm/SD 0.95 mm vs mean M = 3.45 mm/SD 0.76 mm (p=0.855)), MR (mean LMS = 0.30 mm/SD 0.57 mm vs mean M = 0.35 mm/SD 0.67 mm (p=0.801)), CAL (mean LMS = 3.60 mm/SD 1.14 mm vs mean M = 3.55 mm/SD 0.89 mm (p=0.878)), and KM (mean LMS = 2.03 mm/SD 1.08 mm vs mean M = 2.13 mm/SD 0.92 mm (p=0.754)) between LMS and M abutments. LMS abutments showed less BOP than M abutments (26.7% vs 30.8%), but statistically not significant (p = 0.2235). Radiographic bone loss (mean LMS = 0.22 mm/SD 0.44 mm vs mean M = 0.59 mm/SD 0.49 mm) was reduced in the test group in comparison with the control group (p=0.016). In the collected PICF, the levels of pro-inflammatory cytokines IL-1α (median LMS = 180.8 pg/ml vs M = 200.9 pg/ml (p=0.968)) and IL-1ß (median LMS = 60.43 pg/ml vs M = 83.11 pg/ml (p=0.4777)) were lower, and the levels of IL-6 (median LMS = 180.8 pg/ml vs M = 200.9 pg/ml (p<0.0001)) were significantly lower in the test group. In contrast, the levels of IL-8 (median LMS = 255.7 pg/ml vs M = 178.7 pg/ml (p=0.3306)) were higher in the test group, though not significantly. The levels of anti-inflammatory IL-10 were significantly increased in the test group (LMS median = 0.555 pg/ml vs M median = 0.465 pg/ml (p=0.0365)). IL-1ß showed a significant correlation to radiologic bone loss (p=0.0024). The other variables IL-1α, IL-6, IL-8, and IL-10 had no significant correlation to radiological bone loss. CONCLUSION: Within the limitations of this study, titanium implants provided with laser-microtextured surface abutments seem to demonstrate less pro-inflammatory and more anti-inflammatory activity and to show reduced radiographic bone loss compared to machined titanium abutments. CLINICAL RELEVANCE: The use of laser-microtextured surface abutments might have the potential to support peri-implant tissue health.

Fibroblast-like cells change gene expression of bone remodelling markers in transwell cultures.

INTRODUCTION: Periprosthetic fibroblast-like cells (PPFs) play an important role in aseptic loosening of arthroplasties. Various studies have examined PPF behavior in monolayer culture systems. However, the periprosthetic tissue is a three-dimensional (3D) mesh, which allows the cells to interact in a multidirectional way. The expression of bone remodeling markers of fibroblast-like cells in a multilayer environment changes significantly versus monolayer cultures without the addition of particles or cytokine stimulation. Gene expression of bone remodeling markers was therefore compared in fibroblast-like cells from different origins and dermal fibroblasts under transwell culture conditions versus monolayer cultures. METHODS: PPFs from periprosthetic tissues (n = 12), osteoarthritic (OA) synovial fibroblast-like cells (SFs) (n = 6), and dermal fibroblasts (DFs) were cultured in monolayer (density 5.5 × 103/cm2) or multilayer cultures (density 8.5 × 105/cm2) for 10 or 21 days. Cultures were examined via histology, TRAP staining, immunohistochemistry (anti-S100a4), and quantitative real-time PCR. RESULTS: Fibroblast-like cells (PPFs/SFs) and dermal fibroblasts significantly increased the expression of RANKL and significantly decreased the expression of ALP, COL1A1, and OPG in multilayer cultures. PPFs and SFs in multilayer cultures further showed a higher expression of cathepsin K, MMP-13, and TNF-α. In multilayer PPF cultures, the mRNA level of TRAP was also found to be significantly increased. CONCLUSION: The multilayer cultures are able to induce significant expression changes in fibroblast-like cells depending on the nature of cellular origin without the addition of any further stimulus. This system might be a useful tool to get more in vivo like results regarding fibroblast-like cell cultures.

The role of antibiotic-loaded bone cement in complicated knee arthroplasty: relevance of gentamicin allergy and benefit from revision surgery - a case control follow-up study and algorithmic approach.

BACKGROUND: Antibiotic-loaded (particularly gentamicin) bone cement (BC) is widely used in total joint arthroplasty (TJA) to prevent periprosthetic infections (PPIs), but may itself cause implant failure. In light of a complete lack in literature, the objective was to assess the clinical relevance of gentamicin allergy for failure of cemented total knee arthroplasties in 25 out of 250 patients with positive patch test reactions to gentamicin and otherwise unexplained symptoms by evaluating benefits from revision with change to gentamicin-free cement. METHODS: Fifteen of these 25 patients and their treating orthopaedic surgeons agreed to a re-assessment. They were surveyed regarding interim course of therapy and symptoms, including re-assessment of the Knee Injury and Osteoarthritis Outcome Score (KOOS), and underwent follow-up clinical and radiographic investigations. The initial use of gentamicin-loaded BC was reaffirmed by review of the primary implantation operative reports and respective implant passports. Primary and follow-up KOOS scores were analyzed regarding benefits from revision surgery by comparing nine patients with revision to six without revision. RESULTS: Mean follow-up time was 38 months. The entirety of patients experienced an improvement of self-reported symptoms, with revision surgery (i.e., switching to gentamicin-free BC or uncemented total knee arthroplasty) yielding significantly greater improvement (p = 0.031): the nine revised patients reported a significant symptom relief (p = 0.028), contrary to the six unrevised patients (p = 0.14). Interestingly, the decision to proceed with revision surgery was significantly correlated with higher symptom severity (p = 0.05). CONCLUSION: In symptomatic total knee arthroplasty with gentamicin allergy, uncemented revision arthroplasty or change to gentamicin-free BC provides significant symptom relief.

Usefulness of lymphocyte transformation test and in vitro cytokine release in differentiating between independent and cross-reacting nickel/palladium allergy.

BACKGROUND: Often concomitant patch test (PT) reactivity to palladium (Pd) and nickel (Ni) is found. OBJECTIVES: To determine whether lymphocyte transformation test (LTT) could be useful in discrimination between cross-reacting or distinct PT results, and to compare the results with in vitro cytokine production upon Pd or Ni stimulation. MATERIALS AND METHODS: The study population consisted of two groups: 13 individuals with Pd PT reactions (10 with concomitant Ni PT reaction, 3 individuals with only Pd PT reactivity) and 10 Ni/Pd PT negative individuals. LTT and assessment of cytokine release (interferon-gamma, interleukin-5 [IL-5], IL-8, IL-17A, tumor necrosis factor alpha) by cytometric bead assay were performed. RESULTS: All 10 patients with positive PT to Ni and Pd showed positive LTT to Ni (P < .05) as compared with the 10 Pd/Ni PT negative patients-but had no significant LTT reaction to Pd. In all, 9 out of 10 Pd/Ni PT negative patients were also LTT negative to Ni and 10 out of 10 to Pd. In the 3 only Pd PT reactors 2 out of 3 remained LTT negative to Ni and 0 out of 3 to Pd. As a major finding, cytokine production gave clearly enhanced IL-5 response to Ni in Ni PT positive individuals (P < .05), whereas Pd PT reactivity was not linked with such enhanced IL-5 production in vitro to Pd. CONCLUSIONS: Pd and Ni sensitization are mostly found concomitantly, and cross-reactivity is questioned. By different LTT reactions and particularly IL-5 production in vitro, predominant Ni sensitization becomes more evident.

Actovegin® reduces PMA-induced inflammation on human cells.

PURPOSE: The effect of Actovegin® was investigated on PMA- and LPS-induced human peripheral blood mononuclear cells (PBMCs). METHODS: PBMCs (1 × 106 cells/ml) from five blood donors (2 f, 3 m; 45-55 years) were grown in medium and exposed to Actovegin® in the presence or absence of PMA or LPS. Supernatants were collected to assess the concentration of cytokines (TNF-α, IL-1beta, IL-6 and IL-10). The reactive oxygen species (ROS) were assessed by a ROS-GloTM H2O2 assay. RESULTS: Stimulation of cells by PMA or LPS (without Actovegin®) significantly increased the secretion of IL-1beta, IL-6, IL-10 and TNF-α from PBMCs, compared to controls. Pre-treatment of cells with Actovegin® (1, 5, 25, 125 µg/ml) plus PMA significantly decreased the secretion of IL-1beta from PBMCs, compared to controls (PMA without Actovegin®). In contrast, addition of Actovegin® (1, 5, 25, 125 and 250 µg/ml) plus LPS did not alter the IL-1beta production, compared to controls (LPS without Actovegin®). TNF-α, IL-6 and IL-10 do not contribute to the reduction of inflammatory reactions with Actovegin®. CONCLUSIONS: Actovegin® can reduce the PMA-induced IL-1beta release and the ROS production from PBMCs. These findings may help to explain the clinically known positive effects of Actovegin® on athletic injuries with inflammatory responses (e.g., muscle injuries, tendinopathies).

Impact of Periprosthetic Fibroblast-Like Cells on Osteoclastogenesis in Co-Culture with Peripheral Blood Mononuclear Cells Varies Depending on Culture System.

Co-culture studies investigating the role of periprosthetic fibroblasts (PPFs) in inflammatory osteoclastogenesis reveal contrary results, partly showing an osteoprotective function of fibroblasts and high OPG expression in monolayer. These data disagree with molecular analyses of original periosteolytic tissues. In order to find a more reliable model, PPFs were co-cultivated with peripheral blood mononuclear cells (PBMCs) in a transwell system and compared to conventional monolayer cultures. The gene expression of key regulators of osteoclastogenesis (macrophage colony-stimulating factor (MCSF), receptor activator of NF-κB ligand (RANK-L), osteoprotegerin (OPG), and tumor necrosis factor alpha (TNFα)) as well as the ability of bone resorption were analyzed. In monolayer co-cultures, PPFs executed an osteoprotective function with high OPG-expression, low RANK-L/OPG ratios, and a resulting inhibition of osteolysis even in the presence of MCSF and RANK-L. For transwell co-cultures, profound changes in gene expression, with a more than hundredfold decrease of OPG and a significant upregulation of TNFα were observed. In conclusion, we were able to show that a change of culture conditions towards a transwell system resulted in a considerably more osteoclastogenic gene expression profile, being closer to findings in original periosteolytic tissues. This study therefore presents an interesting approach for a more reliable in vitro model to examine the role of fibroblasts in periprosthetic osteoclastogenesis in the future.

Immobilization of Denosumab on Titanium Affects Osteoclastogenesis of Human Peripheral Blood Monocytes.

Immobilization of proteins has been examined to improve implant surfaces. In this study, titanium surfaces were modified with nanofunctionalized denosumab (cDMAB), a human monoclonal anti-RANKL IgG. Noncoding DNA oligonucleotides (ODN) served as linker molecules between titanium and DMAB. Binding and release experiments demonstrated a high binding capacity of cDMAB and continuous release. Human peripheral mononuclear blood cells (PBMCs) were cultured in the presence of RANKL/MCSF for 28 days and differentiated into osteoclasts. Adding soluble DMAB to the medium inhibited osteoclast differentiation. On nanofunctionalized titanium specimens, the osteoclast-specific TRAP5b protein was monitored and showed a significantly decreased amount on cDMAB-titanium in PBMCs + RANKL/MCSF. PBMCs on cDMAB-titanium also changed SEM cell morphology. In conclusion, the results indicate that cDMAB reduces osteoclast formation and has the potential to reduce osteoclastogenesis on titanium surfaces.

Blood cytokine pattern and clinical outcome in knee arthroplasty patients: comparative analysis 5 years after standard versus "hypoallergenic" surface coated prosthesis implantation.

Background and purpose - Metal sensitivity might provoke complications after arthroplasty. Correspondingly, coated "hypoallergenic" implants are of interest but long-term follow-up data are missing. Thus, we assessed immunological and clinical parameters in such patients. Patients and methods - 5 years' follow-up data were obtained from 3 centers, which used either a standard total knee replacement (TKR) or the identical implant with multilayer surface zirconium nitride based coating. Of the 196 patients (mean age 68 years (44-84), 110 females) 97 had arthroplasty with a coated surface, and 99 were treated by a standard TKR of the same type. Investigations were Knee Society Score (KSS), Knee injury and Osteoarthritis Outcome Score (KOOS), radiographic analysis, and cytokine measurement in peripheral blood. Pro- and anti-inflammatory cytokines were evaluated by cytometric beads assay and RT-PCR. Results - Survival rate (Kaplan-Meier) was 98% for coated and 97% for uncoated implants after 5 years. Mechanical axis and KSS pain score (42 vs. 41 (0-50)) were comparable. Most serum cytokine levels were comparable, but mean interleukin-8 and interleukin-10 levels were higher in the group with an uncoated implant. IL-8: 37 (SD 7.5) pg/mL vs. 1.1 (SD 4.3) (p < 0.001); IL-10: 3.6 (SD 2.5) vs. 0.3 (SD 1.8) pg/mL (p < 0.001). Interpretation - There was similar clinical outcome 5 years after standard and surface-coated TKR. In peripheral blood there was an increased pro-inflammatory status, i.e., significant elevation of IL-8 and the anti-inflammatory IL-10, after standard uncoated prosthesis. Any long-term effects of these cytokine changes are unknown.

Metal ion release barrier function and biotribological evaluation of a zirconium nitride multilayer coated knee implant under highly demanding activities wear simulation.

Total knee arthroplasty is a well established treatment for degenerative joint disease, which is also performed as a treatment in younger and middle-aged patients who have a significant physical activity and high life expectancy. However, complications may occur due to biological responses to wear particles, as well as local and systemic hypersensitivity reactions triggered by metal ions and particles such as cobalt, chromium and molybdenum. The purpose of the study was to perform a highly demanding activities (HDA) knee wear simulation in order to compare the wear characteristics and metal ion release barrier function of a zirconium nitride (ZrN) coated knee implant, designed for patients with suspected metal ion hypersensitivity, against an uncoated knee implant made out of CoCrMo. The load profiles were applied for 5 million HDA cycles, which represent 15-30 years of in vivo service depending on the activity level of the patient. Results showed a significant wear rate reduction for the coated group (1.01 ±â€¯0.29 mg/million cycles) in comparison with the uncoated group (2.89 ±â€¯1.04 mg/million cycles). The zirconium nitride coating showed no sign of scratches nor delamination during the wear simulation, whereas the uncoated femurs showed characteristic wear scratches in the articulation areas. Furthermore, the metal ion release from the coated implants was reduced up to three orders of magnitude in comparison with the uncoated implants. These results demonstrate the efficiency of zirconium nitride coated knee implants to reduce wear as well as to substantially reduce metal ion release in the knee joint.