Metal sensitivity in patients with orthopaedic implants

Polylactic acid bioabsorbable implants of the hand: A review

In the treatment of hand fractures, metal implants are often used to allow early range of motion and a stable fixation. Although they provide adequate bone union, metal implants have been known to cause joint stiffness, painful or prominent hardware, and adhesions, often leading to another surgery for hardware removal. Bioabsorbable implants have been shown to offer comparable results for fracture fixation in the hand while removing the complications seen with retained hardware. In this article, we review biomechanical and clinical studies focused on bioabsorbable implants made of polylactic acid used for orthopedic hand injuries in order to promote their continued use and future research.

Cytotoxic effects and comparative analysis of Ni ion uptake by osteoarthritic and physiological osteoblasts

Nickel(Ni)-containing materials have been widely used in a wide range of medical applications, including orthopaedics. Despite their excellent properties, there is still a problem with the release of nickel ions into the patient's body, which can cause changes in the behaviour of surrounding cells and tissues. This study aims to evaluate the effects of Ni on bone cells with an emphasis on the determination of Ni localization in cellular compartments in time. For these purposes, one of the most suitable models for studying the effects induced by metal implants was used-the patient's osteoarthritic cells. Thanks to this it was possible to simulate the pathophysiological conditions in the patient's body, as well as to evaluate the response of the cells which come into direct contact with the material after the implantation of the joint replacement. The largest differences in cell viability, proliferation and cell cycle changes occurred between Ni 0.5 mM and 1 mM concentrations. Time-dependent localization of Ni in cells showed that there is a continuous transport of Ni ions between the nucleus and the cytoplasm, as well as between the cell and the environment. Moreover, osteoarthritic osteoblasts showed faster changes in concentration and ability to accumulate more Ni, especially in the nucleus, than physiological osteoblasts. The differences in Ni accumulation process explains the higher sensitivity of patient osteoblasts to Ni and may be crucial in further studies of implant-derived cytotoxic effects.

No Difference in Revision Rates and High Survival Rates in Large-head Metal-on-metal THA Versus Metal-on-polyethylene THA: Long-term Results of a Randomized Controlled Trial

BACKGROUND

Pseudotumor formation is a well-known complication in metal-on-metal (MoM) THA. Pseudotumors combined with elevated serum ion levels and complaints from patients can lead to high revision rates. Long-term (> 10 years) results obtained from randomized trials comparing large-head MoM THA and conventional metal-on-polyethylene (MoP) THA are lacking regarding revision and survival rates, pseudotumor formation, functional outcomes, and serum ion levels.

QUESTIONS/PURPOSES

At 10 years of follow-up, (1) what is the difference in survival and revision rates between large-head (38 to 60 mm) MoM THA and conventional 28-mm MoP THA? (2) What is the difference in pseudotumor formation between large-head MoM THA and MoP THA? (3) Is there a difference in functional outcome between large-head MoM THA and MoP THA? (4) What is the difference in serum ion levels between large-head MoM THA and MoP THA?

METHODS

Between January 2006 and December 2008, 104 patients were randomized to receive either cementless MoM THA (50 patients) or cementless MoP THA (54 patients). In all, 78% (81 of 104) of patients completed the 10-year postoperative follow-up: 36 patients with MoM THA (72%; six patients lost to follow-up) and 45 with MoP THA (83%; four lost to follow-up). In the MoM group, 47% (17) were men, and the patients had a mean ± SD age of 60 ± 5 years. In the MoP group, 38% (17) were men, and the patients had a mean age of 61 ± 5 years. All baseline characteristics were similar between the groups. At 10 years of follow-up, all patient records were screened for revision surgery or complications, and the primary endpoint was survivorship free from revision for any cause at the 10-year follow-up interval, which we analyzed using a Kaplan-Meier survival analysis. All patients had a CT scan to determine the pseudotumor classification, which was reviewed by an independent radiologist. Functional outcome was measured using the patient-reported Oxford Hip Score and Harris Hip Score; the latter was assessed by a blinded nurse practitioner. Finally, serum ion cobalt and chrome concentrations were measured at 10 years postoperatively. Because the a priori sample size calculation for this randomized controlled trial was based on a different endpoint, a post hoc power analysis was performed for this long-term follow-up study, with survival as the primary outcome. It showed that considering the number of included patients, this study would have sufficient power (one-sided testing, alpha 0.05, power 80%) to discern a difference of 20% in the survival rate between the MoP and MoM groups (95% versus 75%).

RESULTS

With the numbers available, there was no difference in survivorship free from revision for any cause between the MoP group and MoM group at 10 years (95% [95% CI 85% to 98%] versus 92% [95% CI 82% to 98%]; p = 0.6). A higher percentage of patients in the MoM group had pseudotumors on CT than those in the MoP group did, but pseudotumors were observed in both groups (56% [20 of 36] in the MoM group versus 22% [10 of 45] in the MoP group, relative risk 1.8 [95% CI 1.2 to 2.6]; p = 0.002). A higher proportion of elevated cobalt and chrome levels was found in the MoM group (19% and 14%, respectively) than in the MoP group (0% for both cobalt and chrome) (cobalt: RR 1.2 [95% CI 1.1 to 1.5]; p = 0.002; chrome: RR 1.2 [95% CI 1.0 to 1.3]; p = 0.01). In 25% of the patients with pseudotumors (5 of 20 patients), there were elevated serum cobalt levels. None of the 23 patients without pseudotumors had elevated cobalt levels (RR 1.3 [95% CI 1.0 to 1.7]; p = 0.01). There was no difference in functional outcome between study groups, nor a difference between patients with a pseudotumor and those without.

CONCLUSION

This study showed that the survival of patients with large-head MoM THA was high and comparable to that of those with MoP THA, which contrasts with the high revision rates reported by others. Although some patients with MoP THAs experienced pseudotumors, the risk of a pseudotumor was much greater in MoM hips, and serum ion levels were higher in patients who received an MoM THA. For these reasons and unknown future complications, continued surveillance of patients with MoM THAs seems important.

LEVEL OF EVIDENCE

Level I, therapeutic study.

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.

A literature review and expert consensus statement on diagnostics in suspected metal implant allergy

BACKGROUND

Although rare, allergic reactions to metal implants represent a diagnostic challenge in view of missing guidelines.

OBJECTIVES

To develop an European expert consensus on characteristics of metal allergy reactions and the utility of various diagnostic tools in suspected metal implant allergy.

METHODS

A nominal group technique (NGT) was applied to develop consensus statements. Initially an online literature database was created on a secure server to enable a comprehensive information. Twenty-three statements were formulated on potential aspects of metal implant allergy with a focus on diagnostics and grouped into five domains. For the consensus development, the panel of 12 experts initially did refine and reformulate those statements that were ambiguous or had unclear wording. By face-to-face (9/12) or virtual participation (3/12), an anonymous online voting was performed.

RESULTS

Consensus (≥80% of agreement) was reached in 20/23 statements. The panel agreed that implant allergy despite being rare should be considered in case of persistent unexplained symptoms. It was, however, recommended to allow adequate time for resolution of symptoms associated with healing and integration of an implant. Obtaining questionnaire-aided standardized medical history and standardized scoring of patient outcomes was also considered an important step by all experts There was broad consensus regarding the utility/performance of patch testing with additional late reading. It was recognized that the lymphocyte transformation test (LTT) has to many limitations to be generally recommended. Prior to orthopaedic implant, allergy screening of patients without a history of potential allergy to implant components was not recommended.

CONCLUSIONS

Using an expert consensus process, statements concerning allergy diagnostics in suspected metal implant allergy were created. Areas of nonconsensus were identified, stressing uncertainty among the experts around topics such as preoperative testing in assumed allergy, histological correlate of periimplant allergy and in vitro testing, which underscores the need for further research.

The contribution of metal allergy to the failure of metal alloy implants, with special reference to titanium: Current knowledge and controversies

After almost three-quarters of a century during which contact dermatologists have often struggled to comprehend the relationship between metal allergy and failure of metal-alloy containing implant, it is possible to say that a relationship does exist, particularly for cobalt and chromium, but also for nickel. There is still debate as to whether allergy develops as a consequent of failure but thenceforth contributes to it, or whether sensitisation starts first and induces failure secondarily-opinion probably favours the first. Metal-on-polypropylene articulations were associated with few metal allergic problems but now are less favoured by orthopaedists due to plastic wear products causing osteolysis and pseudotumour formation through local inflammation. New metal alloys are regularly being introduced such that interested dermatologists need to stay on top of the situation. The jury is still out as to whether the recent favouring of titanium-containing alloys will confirm them to be more inert allergenically. Case reports do show some clinical reactions to titanium-containing implants and patch test series have inferred sometimes quite a high background rate of allergy, but interpretation must be tempered by the awareness that titanium salts on patch testing have a tendency to cause irritant reactions. Blood monitoring of metal ion values is now recommended in certain situations after joint replacement and increasing levels may be an indication that allergy with joint failure can develop, in which case patch testing is indicated, and suggested series are available. Predictive patch testing, whilst generally not recommended in the past, has been introduced into some protocols often by non-dermatologists, such that it is now needed for temporo-mandibular joint and Nuss bar insertion, and it can be anticipated that this may become more commonplace in the future. One of the major current deficits for patch testers is standardised guidance on which preparation or preparations to use for suspected titanium allergy. One suggestion is 0.5% titanium sulphate in petrolatum, though experience in at least one centre suggests the use of a battery of titanium salts might be desirable.

Hypersensitivity to metals in metal-on-metal hip arthroplasty: a prospective study of one hundred and thirty five lymphocyte transformation tests

BACKGROUND

Metal allergy remains a controversial topic in the orthopaedic community. It is not known if or to what degree metal sensitivity contributes to inflammatory soft tissue failures, unexplained residual pain, or clinical complications after total joint replacement with metal prostheses.

METHODS

We investigated the efficacy of the lymphocyte transformation test (LTT) in predicting adverse outcomes in patients after receiving a metal joint replacement. Our study cohort consists of 135 metal-on-metal hip resurfacing arthroplasty cases performed between 2013 and 2015. All study patients had an LTT preoperatively. We retrospectively analyzed clinical outcomes and failures for our cohort.

RESULTS

There was no difference in LTT reactivity between men and women. Of the 135 patients tested, 46 (34.1% of cohort) tested positive to at least one of the materials comprising their implant, and 78 patients (57.8%) had at least one reactive score to any component of the LTT. After a minimum follow-up of two years, we did not observe an allergic response to the implant in any patients. There were no failures requiring revision. We observed a 2.2% rate of moderate residual pain; no patients with residual pain tested positive for metal sensitivity. When patients with moderate-high LTT reactivity (30.4% of cohort) were compared to the remainder of the study group, there was no difference in HHS or UCLA activity score. There was no correlation between blood metal ion levels and LTT reactivity.

CONCLUSION

We were unable to prove any predictive value of the LTT. We failed to identify hypersensitivity to metals in patients with metal-on-metal hip resurfacing arthroplasty.

Additively manufactured Ti-Ta-Cu alloys for the next-generation load-bearing implants

Bacterial colonization of orthopedic implants is one of the leading causes of failure and clinical complexities for load-bearing metallic implants. Topical or systemic administration of antibiotics may not offer the most efficient defense against colonization, especially in the case of secondary infection, leading to surgical removal of implants and in some cases even limbs. In this study, laser powder bed fusion was implemented to fabricate Ti3Al2V alloy by a 1:1 weight mixture of CpTi and Ti6Al4V powders. Ti-Tantalum (Ta)-Copper (Cu) alloys were further analyzed by the addition of Ta and Cu into the Ti3Al2V custom alloy. The biological, mechanical, and tribo-biocorrosion properties of Ti3Al2V alloy were evaluated. A 10 wt.% Ta (10Ta) and 3 wt.% Cu (3Cu) were added to the Ti3Al2V alloy to enhance biocompatibility and impart inherent bacterial resistance. Additively manufactured implants were investigated for resistance against Pseudomonas aeruginosa and Staphylococcus aureus strains of bacteria for up to 48 h. A 3 wt.% Cu addition to Ti3Al2V displayed improved antibacterial efficacy, i.e. 78%-86% with respect to CpTi. Mechanical properties for Ti3Al2V-10Ta-3Cu alloy were evaluated, demonstrating excellent fatigue resistance, exceptional shear strength, and improved tribological and tribo-biocorrosion characteristics when compared to Ti6Al4V. In vivo studies using a rat distal femur model revealed improved early-stage osseointegration for alloys with 10 wt.% Ta addition compared to CpTi and Ti6Al4V. The 3 wt.% Cu-added compositions displayed biocompatibility and no adverse inflammatory response in vivo. Our results establish the Ti3Al2V-10Ta-3Cu alloy's synergistic effect on improving both in vivo biocompatibility and microbial resistance for the next generation of load-bearing metallic implants.

Pathophysiology of the Toxic Effects in Metallic Implants

Implants play a very crucial role in modern era of medicine and address several needs in all the medical specialties. Both essential and nonessential metals released from implants at high concentrations can impair biological functions and result in toxicity involving multiple systems of the body. Furthermore, the toxicity information is typically based on exposure through dietary intake and/or occupational/environmental exposure but, since the in vivo implant environment and its composition is different or unknown, individual implants toxic effects needs to be elaborated. Several clinical and nonclinical assessment tools are advised by FDA to evaluate biocompatibility issues, such as risk of immunological response, tissue destruction or overgrowth, and other adverse reactions. The Center for Devices and Radiological Health (CDRH) Biocompatibility Guidelines state that biocompatibility end points caused by metallic implants includes cytotoxicity, sensitization, acute and chronic systemic toxicity, pyrogenicity, genotoxicity, carcinogenicity, implantation, hemocompatibility, reproductive abnormalities, developmental toxicity and biodegradation. Exposure to metal ions which acts as haptens can lead to both local and systemic hypersensitivity reactions which are generally believed to be a Type IV (delayed hypersensitivity) response. Currently, most assessment tools of implant associated hypersensitivity are based on skin sensitization which provides further scopes for research in understanding patient specific immune response causing systemic hypersensitivity.

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.

Systemic allergic contact dermatitis to palladium, platinum, and titanium: mechanisms, clinical manifestations, prevalence, and therapeutic approaches

Contact dermatitis (CD) is an inflammatory skin disease of eczema that is elicited by chemicals or metal ions that have toxic effects without eliciting a T-cell response (contact elicitation) or by small reactive chemicals that modify proteins and induce innate and adaptive immune responses (contact allergens). The clinical condition is characterized by localized skin rash, pruritus, redness, swelling, and lesions, which are mainly detected by patch tests and lymphocyte stimulation. Heavy metals such as palladium (Pd), platinum (Pt), and titanium (Ti) are ubiquitous in our environment. These heavy metals have shown CD effects as allergic agents. Immunological responses result from the interaction of cytokines and T cells. Occupational metal CD accounts for most cases of work-related cutaneous disorders. In this systematic review, the allergic effects of heavy metals, including Pd, Pt, and Ti, and the mechanisms, clinical manifestations, prevalence, and therapeutic approaches are discussed in detail. Furthermore, the therapeutic approaches introduced to treat CD, including corticosteroids, topical calcineurin inhibitors, systemic immunosuppressive agents, phototherapy, and antihistamines, can be effective in the treatment of these diseases in the future. Ultimately, the insights identified could lead to improved therapeutic and diagnostic pathways.

In vivo corrosion on retrieved hip endoprostheses and in vitro effects of corrosion products on bone mineralization

In vivo corrosion of modular endoprostheses remains a great concern, as the release of heavy metal ions can impair the implant's service life and the wellbeing of the patient. The detailed corrosion mechanisms that occur in vivo are so far not completely understood. In this context, the effects of implant released cobalt (Co) and chromium (Cr) ions on osteoblast mineralization and gene expression have not been investigated extensively. This comprehensive study aimed at furthering the understanding of in vivo implant corrosion from the clinical signs via prosthesis retrievals and histology of the synovial membranes down to the molecular processes instigated by corrosion products and its effects on bone mineralization. A detailed in vivo failure analysis was performed investigating 22 retrieved hip endoprostheses from different manufacturers and taper material combinations. The aim was to find a correlation of taper damage and especially corrosion to susceptible biomedical alloys and its effect on periprosthetic tissue as well as the clinical implant performance with regard to revision diagnosis and presence of radiolucent lines (RLL). A second part investigated the effects of Co and Cr ions on the in vitro mineralization process of osteoblasts. Cell cultures were exposed to relevant concentrations of CoCl2 and CrCl3 (0 μM, 100 μM, 200 μM) with and without addition of phosphate. Mineralization behavior was analyzed with Alizarin Red assay and Von Kossa staining of calcium depots, alkaline phosphatase activity of osteoblasts and gene expression was analyzed with real time quantitative PCR. The retrieval study provides evidence of in vivo fretting and crevice corrosion on all metallic tapers combined with either ceramic or metal femoral heads. Within the modular taper junctions, selective dissolution of the α phase occurred in wrought TiAl6V4 alloys, and etching of the fine-grained wrought CoCr28Mo6 alloy implants was observed in formed crevices. In addition, significant amounts of wear particles and corrosion products were detected in retrieved synovial membranes. An increased risk for the occurrence of a RLL in the proximal zones was determined for patients with a corroded mixed metal taper. Whereas Co ions have hardly any effects on mineralization, Cr ions cause a significant concentration dependent decrease in mineralization rate of osteoblasts. However, this effect is alleviated by addition of a phosphate source. Our data reveal that Cr ions depleted dissolved phosphates by forming an insoluble complex (CrPO4), which inhibits the phosphate dependent mineralization process. No significant effect of the heavy metal ions on osteoblast activity by means of alkaline phosphate activity as well as on gene expression is determined. This study broadens the understanding of in vivo corrosion of metallic modular implants and its clinically relevant effects on mineralization. Based on these findings, in vivo corrosion of CoCr28Mo6 endoprostheses should be limited to avoid inhibitory effects of Cr3+ on bone mineralization which can contribute to premature implant failure.

Advancements in Additive Manufacturing of Tantalum via the Laser Powder Bed Fusion (PBF-LB/M): A Comprehensive Review

Additive manufacturing (AM) exhibits a prime increment in manufacturing technology development. The last few decades have witnessed massive improvement in this field of research, including the growth in the process, equipment, and materials. Irrespective of compelling technological advancements, technical challenges provoke the application and development of these technologies. Metal additive manufacturing is considered a prime sector of the industrial revolution. Various metal AM techniques, including Selective Laser Sintering (SLS), Laser Powder Bed Fusion (PBF-LB/M), and Electron Beam Powder Bed Fusion (PBF-EB/M), have been developed according to materials and process classifications. PBF-LB/M is considered one of the most suitable choices for metallic materials. PBF-LB/M of tantalum has become a hot topic of research in the current century owing to the high biocompatibility of tantalum and its high-end safety applications. PBF-LB/M of porous Ta can direct unexplored research prospects in biomedical and orthopedics by adapting mechanical and biomedical properties and pioneering implant designs with predictable features. This review primarily examines the current advancements in the additive manufacturing of tantalum and related alloys using the PBF-LB/M process. The analysis encompasses the evaluation of process parameters, mechanical properties, and potential biological applications. This will offer the reader valuable insights into the present state of PBF-LB/M for tantalum alloys.

Effect of Enterococcus faecalis Biofilm on Corrosion Kinetics in Titanium Grade 4 Alloys with Different Surface Treatments

E. faecalis has been associated with bacteremia, sepsis, and bacterial endocarditis and peri-implantitis. This microorganism can remain in the alveolus even after extraction of the root remnant. This study aimed to evaluate the corrosion on different surfaces of commercially pure titanium (Ti) grade 4 (Ticp-G4) as a function of the bacterial biofilm effect of Enterococcus faecalis. A total of 57 discs were randomly divided according to their surface finish (n = 19). For microbiological analysis (n = 9), the discs were placed in 12-well plates containing E. faecalis culture and incubated at 37 °C for 7 days. The results show that for the intergroup analysis, considering the "electrolyte" factor, there was a difference between the groups. There was greater biofilm formation for the D.A.Zir group, with greater electrochemical exchange for Biofilm, and the presence of biofilm favored greater electrochemical exchange with the medium.

Patient Journey Map: Metal Hypersensitivity

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

Bilateral Failure of Oxidized Zirconium Implants in Total Knee Arthroplasty

Oxidized zirconium was first introduced in total hip arthroplasty procedures to merge the strengths of metal and ceramic into one prosthetic. The subsequent adoption of oxidized zirconium (oxinium) for total knee arthroplasty is attributed to the theory of causing less wear on the tibial components compared to the alternative, cobalt chromium. However, the superficial layer of the femoral component is occasionally breached, exposing the softer zirconium substrate. Multiple mechanisms leading to zirconium substrate exposure have been explained, including collateral ligament instability and polyethylene wear. Such a failure may lead to damage to the periprosthetic tissues and often requires a revision procedure. In the current case report, we present a case of bilateral total knee arthroplasty with oxidized zirconium components that resulted in catastrophic failure and subsequent revision with hinged knee prostheses.

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.

Metal reactivity is present in dogs with tibial plateau leveling osteotomy and total hip replacement implants

OBJECTIVE

Determine whether dogs with well-functioning orthopedic metal implants can develop metal reactivity.

SAMPLE

Client-owned dogs that had tibial plateau leveling osteotomy (TPLO) or total hip replacement (THR) implants for 12 months or more and control dogs with no implants.

PROCEDURES

Lymphocyte transformation testing was performed by exposing peripheral blood lymphocytes to nickel (Ni), chromium (Cr), cobalt (Co), or a combination of these metals. Lymphocyte proliferation was assessed with flow cytometry. Lymphocyte stimulation indexes (SIs) were calculated. A SI > 2 was considered reactive. Median SIs of dogs in response to metal exposure were compared statistically.

RESULTS

Samples from 10 dogs with TPLO, 12 dogs with THR, and 7 control dogs were analyzed. Six dogs out of 22 with metal implants had a reactive SI to 1 or more metals, while 2 of 7 control dogs had a SI > 2 when exposed to nickel only. When all metals were considered, no differences in metal reactivity were found between TPLO, THR, and control groups.

CLINICAL RELEVANCE

Metal reactivity is present in dogs and can be identified using lymphocyte transformation testing. Reactivity to Ni is present in dogs with and without metal implants. Reactivity to Co and Cr occurs in some dogs with metal implants.

Hypersensitivity reactions to metals in spine surgery

Hypersensitivity to orthopedic devices is a rare condition with an underestimated incidence due to the lack of diagnostic guideline and ambiguous clinical manifestations. Although hypersensitivity to metal is common, a few cases of hypersensitivity reactions have been reported after spinal instrumentation. Spinal fusion and stabilization require a wide range of devices such as screws, wires, bands, and artificial disk replacement devices. Spinal instrumented surgeries are different from total joint arthroplasty in several aspects such as degree and pattern of motion, loading environment, and adjacent tissues with distinct characteristics. The interval for hypersensitivity reactions to occur after spinal metallic implantation is usually weeks to months. The present review covers the topic of hypersensitivity reactions that have been reported after spinal surgeries with the focus on cutaneous presentations.

Hypersensitivity and lymphocyte activation after total hip arthroplasty

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

Examination of colorectal cancer cases with metal allergy

PURPOSE

To report our initiatives and treatment results for patients with colorectal cancer with metal allergy.

METHODS

A total of 27 patients (2.6%) with a history of metal contact dermatitis were identified among 1027 patients who underwent curative resection of colorectal cancer from 2014 to 2020. The results of the patch test, perioperative results, and postoperative colonoscopy findings were also investigated.

RESULTS

The patch test for metal allergens and staples was performed in 21 patients (77.8%), and 13 of them (61.9%) tested positive for at least one metal allergen. Ni (38.1%), Co (28.6%), and Pd (19.0%) showed higher positive rates than other metals, and 1 patient (4.8%) tested positive for staples. Stapled anastomosis/suturing was performed as planned in 15 of 27 patients. In 10 patients, the anastomosis method was changed from stapled to hand-sewn according to the no-patch test results (60%), positivity for multiple metals (20%), positivity for staples (10%), and surgeon's judgment (10%). No complications and abnormal colonoscopy findings were found to be associated with stapled anastomosis/suturing.

CONCLUSION

The patch test is useful for selecting an optimal anastomosis method for patients with suspected metal allergy.

Dental Implants and Implant Coatings: A Focus on Their Toxicity and Safety

Dental implants are medical devices that are surgically inserted into the patient's jawbone by an orthodontist to act as roots of missing teeth. After the implantation, the maxilla or mandible integrates with the surface of the dental implant. This process, called "osseointegration," is an important period to ensure the long-term use of dental implants and prevent implant failures. Metal implants are the most used implant materials. However, they have disadvantages such as corrosion, metal ion release from metal implant surfaces and associated toxicity. To avoid these adverse effects and improve osseointegration, alternative dental implant materials such as ceramics, polymers, composites, and novel surface modification technologies have been developed. The safety of these materials are also of concern for toxicologists. This review will give general information about dental implant materials, osseointegration and successful implantation process. Moreover, we will focus on the new surface coatings materials for of dental implants and their toxicity and safety concerns will be discussed.

Characterization of ion release from a novel biomaterial, Molybdenum-47.5Rhenium, in physiologic environments

BACKGROUND CONTEXT

Metals from spinal implants are released into surrounding tissues by various mechanisms. Metal ion release has been associated with clinical implant failure, osteolysis, and remote site accumulation with adverse events. Significant corrosion and associated metal ion release has been described with currently used spinal implant alloys. A novel metal alloy, Molybdenum-47.5Rhenium alloy (MoRe®), was approved for use in medical implants in 2019 by the FDA.

PURPOSE

To evaluate the metal ion release profile of MoRe alloy after immersion in both a stable physiologic, as well as in an inflammatory environment.

STUDY DESIGN

In vitro study.

METHODS

The ion release profile of the MoRe alloy was comprehensively evaluated in-vitro after prolonged immersion in physiologic and inflammatory environments. Ion concentration analyses were then conducted using inductively coupled plasma-mass spectrometry (ICP-MS) methods. Comparative testing of titanium (Ti-6Al-4V) and cobalt chromium (Co-28Cr-6Mo) was also performed.

RESULTS

Under baseline physiologic conditions, the MoRe alloy demonstrates very low molybdenum and rhenium ion release rates throughout the 30-day test period. During the first time interval (day 0-1), low levels of molybdenum and rhenium ions are detected (<0.3 μg/cm² day) followed by a rapid reduction in the ion release rates to <0.05 μg/cm² day during the second time interval (days 1-3) followed by a further reduction to very low steady-state rates <0.01 μg/cm² day during the third time interval (days 3-7), which were maintained through 30 days. In the inflammatory condition (H₂O₂ solution), there was a transient increase in the release of molybdenum and rhenium ions, followed by a return to baseline ion release rates (days 2-4), with a further reduction to low steady-state rates of ∼0.01 μg/cm² day (days 4-8). The measured molybdenum and rhenium ion release rates in both steady state (<0.01 μg/cm² day), and inflammatory environments (0.01 μg/cm² day) were far below the established FDA-permitted daily exposure (PDE) of 1,900 μg/cm² day for molybdenum and 4,400 μg/cm² day for rhenium. In contrast, titanium and cobalt chromium approached or exceeded their established PDE values in an inflammatory environment.

CONCLUSIONS

The novel biomaterial MoRe demonstrated a lower metal ion release profile in both a physiologic and inflammatory environment and was well below the established PDE.  Comparative testing of the cobalt-chromium and titanium alloys found higher levels of ion release in the inflammatory environment that exceeded the PDE for cobalt and vanadium.

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

BACKGROUND

Oxidized zirconium (Oxinium), titanium nitride (TiN) or titanium niobium nitride (TiNbN) coated implants became in recent years available for an increasing amount of total knee arthroplasty (TKA) systems. The hypothesis of this study was that the use of TiNbN-coated components would not lead to inferior results compared to conventional implants and that none of the metal hypersensitivity patients receiving TiNbN-coated implants would require revision for metal allergy.

MATERIALS AND METHODS

This retrospective study compared 53 Titanium Niobium Nitride coated TKA with 103 conventional chrome cobalt implants of the same design. Patients were evaluated at a minimal follow-up of 3 years.

RESULTS

No differences in clinical, radiological or patient-reported outcome measurements were observed between these groups. A survivorship of 96% without differences in revision rates was observed at medium-term follow-up of 6.5 years.

DISCUSSION

Metal allergy leading to contact or generalized dermatitis after TKA is very rare and usually linked to chrome or cobalt hypersensitivity. Nickel release from knee implants has not been shown to lead to cutaneous symptoms, but unexplained pain and swelling, peri-prosthetic osteolysis and component loosening remain potential issues not fully understood. The use of coated implants eliminates this factor from the diagnostic equation in case of postoperative dissatisfaction.

CONCLUSION

The use of titanium niobium nitride coated implants for primary knee osteoarthritis in self-reported metal hypersensitivity patients shows similar outcomes and survivorship rates as conventional chrome cobalt TKA, with no revisions for allergy at medium-term follow-up.

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.

Allergy Testing Has No Correlation with Intraoperative Histopathology from Revision Total Knee Arthroplasty for Implant-Related Metal Allergy

Lymphocyte transformation testing (LTT) is often used in the workup for possible metal allergy after total knee arthroplasty (TKA) but the correlation of this test with other diagnostic metal-allergy findings in patients undergoing revision TKA for suspected metal allergy has not been established. A single-center, single-surgeon cohort of 19 TKAs in which both components were revised for presumed implant-related metal allergy based on history, physical, and LTT testing, to nonnickel-containing implants were retrospectively identified. Histopathologic samples obtained intraoperatively were semiquantitatively analyzed using both the Hospital for Special Surgery (HSS) synovial pathology score and the Campbell aseptic lymphocyte-dominant vasculitis-associated lesion (ALVAL) score. As histopathology control group, we included in the study an additional cohort of 17 patients who received aseptic revision TKA and had no history of reported or tested metal sensitivity. All preoperative LTT results were highly reactive to nickel. However, this did not correlate with local periarticular tissue response in 18 of 19 cases which demonstrated a low HSS synovial score (mean: 3.8 ± 2.8, of a maximum score of 28) and the low Campbell ALVAL scores (mean: 2.5/10 ± 1.3, of a maximum score of 10). There were not any significant differences between the study group (suspected implant-related metal allergy) and the control group (nonsuspected implant-related metal allergy) in regard to (1) the Campbell score and (2) the HSS synovial inflammatory score. Knee Society Clinical Rating System (KSCRS) function score improved significantly after revision (mean postoperative increase: 34.0 ± 17. 2; p < 0.001), as well as mean visual analog scale (VAS) pain (mean postoperative decrease: 33.3 ± 26.4; p < 0.01) score. The short-term survival rate (at mean follow-up of 26.1 months) of this patient cohort was 100%. In this cohort of revised TKA patients with suspected nickel allergy based on clinical presentation and LTT positive results, intraoperative histopathology was essentially normal. However, all patients with suspected nickel allergy showed a significant clinical and functional improvement with excellent short-term survival rates. The clinical significance of a positive LTT needs further study.

Team Approach: Metal Hypersensitivity in Total Joint Arthroplasty

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As total joint arthroplasty volume continues to grow nationwide, more uncommon complications such as metal implant hypersensitivity are reported with greater frequency in the literature.

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Metal hypersensitivity is a challenging diagnosis given the potentially vague symptomology. It should be considered a diagnosis of exclusion, necessitating careful consideration of other potential etiologies of a failing implant before arriving at the final diagnosis of metal hypersensitivity.

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Patients can experience substantial morbidity from implant rejection and in severe, refractory cases may even require revision arthroplasty and conversion to a hypoallergenic implant.

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Given the complex nature of the condition, successful treatment of metal hypersensitivity to orthopaedic implants is best achieved through the use of a multidisciplinary, team-based approach. Immunologists, radiologists, and infectious disease physicians as well as orthopaedic surgeons and mechanical engineers are all vital in appropriate diagnosis and treatment of the condition.

Immune response differences in degradable and non-degradable alloy implants

Alloy based implants have made a great impact in the clinic and in preclinical research. Immune responses are one of the major causes of failure of these implants in the clinic. Although the immune responses toward non-degradable alloy implants are well documented, there is a poor understanding of the immune responses against degradable alloy implants. Recently, there have been several reports suggesting that degradable implants may develop substantial immune responses. This phenomenon needs to be further studied in detail to make the case for the degradable implants to be utilized in clinics. Herein, we review these new recent reports suggesting the role of innate and potentially adaptive immune cells in inducing immune responses against degradable implants. First, we discussed immune responses to allergen components of non-degradable implants to give a better overview on differences in the immune response between non-degradable and degradable implants. Furthermore, we also provide potential areas of research that can be undertaken that may shed light on the local and global immune responses that are generated in response to degradable implants.

Periarticular metal hypersensitivity complications of hip bearings containing cobalt-chromium

Hip joints with bearings composed of cobalt-chromium alloy (metal-on-metal bearings) have been one of the most widely used implants in joint replacement arthroplasty. Unfortunately, these implants can contribute to a complication called aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL), a type IV metal hypersensitivity response around the joint. Consistent with such bearings, increased metal debris can be found in the surrounding fluids and in remote tissues and organs, due to wear and corrosion. It is hypothesized that metal ions released from the prosthesis (including Co2+) can potentially form haptens with proteins such as serum albumin in synovial fluid that in turn elicit ALVAL. Generally, elevated cobalt and chromium levels in synovial fluids may indicate implant failure. However, such measurements cannot be used as a reliable tool to predict the onset of ALVAL. To detect ALVAL, some diagnostic tests, questionnaires and imaging techniques have been used clinically with some success, but a standardized approach is lacking. At present, guidelines for implant usage and patient management are ambiguous and inconsistent across health care authorities. To reduce and better manage the development of ALVAL, further research into the precise molecular mechanism(s) by which ALVAL develops is urgently needed. Identification of diagnostic and prognostic biomarkers for ALVAL is required, as are more standardized guidelines for surgery and patient management.

Pediatric fractures following implant removal: A systematic review

OBJECTIVES

To evaluate the available literature for postoperative fracture rates following implant removal in the pediatric population.

METHODS

A systematic review of articles in the PubMed and Embase computerized literature databases from January 2000 to June 2022 was performed using PRISMA guidelines. Randomized controlled trials, case-control studies, cohort studies (retrospective and prospective), and case series involving pediatric patients that included data on fracture rate following removal of orthopedic implants were eligible for review. Two authors independently extracted data from selected studies for predefined data fields for implant type, anatomic location of the implant, indication for implantation, fracture or refracture rate following implant removal, mean time to implant removal, and mean follow-up time.

RESULTS

Fifteen studies were included for qualitative synthesis. Reported fracture rates following implant removal vary based on several factors, with an overall reported incidence of 0%-14.9%. The available literature did not offer sufficient data for conduction of a meta-analysis.

CONCLUSION

Our systematic review demonstrates that fracture following implant removal in pediatric patients is a relatively frequent complication. In children, the forearm and femur are the most commonly reported sites of fracture following removal of implants. Traumatic fractures treated definitively with external fixation have the highest reported aggregate rate of refracture. Knowledge of the incidence of this risk is important for orthopedic surgeons. There remains a need for well-designed studies and trials to further clarify the roles of the variables that contribute to this complication.

Lymphocyte transformation test reveals low prevalence of true metal hypersensitivity among pre-operative total knee arthroplasty patients

PURPOSE

The aims of this study were to determine the prevalence of metal hypersensitivity, and identify pre-operative factors which could predict susceptibility to hypersensitivity reactions among patients scheduled for primary total knee arthroplasty (TKA). The present study used a testing method consistent with the recognised biological response to metals.

METHODS

A prospective cross-sectional analysis of 220 patients was conducted. All patients received a testing protocol using lymphocyte transformation test to evaluate reactivity to possible contents of orthopaedic implants. Test response is interpreted as stimulation index (SI) values. A comprehensive questionnaire was used to evaluate prior exposure. Patients were categorised according to SI values and the odds ratios (OR) were calculated as comparative effect measure for each predetermined prior exposure factor.

RESULTS

The prevalence of metal sensitivity response was 28% (n = 61) among patients with susceptibility to at least one agent (SI = 2 to 4.9), and 3.2% (n = 7) among patients with true hypersensitivity (SI ≥ 5). The population-weighted prevalence, adjusted for sampling weights of symptomatic knee osteoarthritis, was SI ≥ 5 = 4.7% (95% CI 0.4-11.8%) and SI ≥ 2 = 35.2% (95% CI 24.8-48.6%). Stimulation index levels of response to materials were markedly varied with the highest being aluminium. Female sex, smoking history, cutaneous reaction to jewellery, occupational exposure, and dental procedures were among factors shown to increase the odds of having higher reactivity response to tested metals. Nevertheless, patients with well-functioning prior contralateral TKA did not appear at greater risk of having either sensitivity or susceptibility with odds ratio (OR) = 0.2 (95% CI 0.01-3.2), p: NS and OR = 0.6 (95% CI 0.3-1.2), p: NS, respectively. Prior positive patch test was neither predictor of susceptibility to hypersensitivity OR = 1.2 (95% CI 0.6-2.6) p: NS nor predictor of true hypersensitivity OR = 0.7 (95% CI 0.08-6.1), p: NS.

CONCLUSION

Among patients scheduled for primary TKA with no prior clinical features of metal allergy the prevalence of true hypersensitivity to at least one metal is just over 3%. Patients are likely to encounter a material to which they have pre-existing susceptibility to hypersensitivity. With certain prior exposure factors, there was increased susceptibility to metal hypersensitivity reaction evoking an acquired condition.

LEVEL OF EVIDENCE

Level II, prospective cross-sectional study.

Consensus Guidelines on Interventional Therapies for Knee Pain (STEP Guidelines) from the American Society of Pain and Neuroscience

Knee pain is second only to the back as the most commonly reported area of pain in the human body. With an overall prevalence of 46.2%, its impact on disability, lost productivity, and cost on healthcare cannot be overlooked. Due to the pervasiveness of knee pain in the general population, there are no shortages of treatment options available for addressing the symptoms. Ranging from physical therapy and pharmacologic agents to interventional pain procedures to surgical options, practitioners have a wide array of options to choose from – unfortunately, there is no consensus on which treatments are “better” and when they should be offered in comparison to others. While it is generally accepted that less invasive treatments should be offered before more invasive ones, there is a lack of agreement on the order in which the less invasive are to be presented. In an effort to standardize the treatment of this extremely prevalent pathology, the authors present an all-encompassing set of guidelines on the treatment of knee pain based on an extensive literature search and data grading for each of the available alternative that will allow practitioners the ability to compare and contrast each option.

The effect of Nickel hypersensitivity on the outcome of total knee arthroplasty and the value of skin patch testing: a systematic review

Background

To assess the Nickel sensitizing potential of total knee arthroplasty (TKA), explore the relationship between hypersensitivity and clinical outcomes, and evaluate the utility of skin patch testing pre- and/or postoperatively.

Materials and methods

A literature search was performed through EMBASE, Medline and PubMed databases. Articles were screened independently by two investigators. The level of evidence of studies was assessed using the Oxford Centre for Evidence-Based Medicine Criteria and the quality evaluated using the Methodological Index for Non-randomized Studies and Cochrane risk-of-bias tools.

Results

Twenty studies met the eligibility criteria, reporting on 1354 knee arthroplasties. Studies included patients undergoing primary or revision TKA, pre- and/or postoperatively, and used patch testing to identify Nickel hypersensitivity. Prevalence of Nickel hypersensitivity ranged from 0% to 87.5%. One study compared the prevalence of Nickel hypersensitivity in the same patient group before and after surgery and noted newly positive patch test reactions in three patients (4.2%). Three studies reported lower prevalence of Nickel hypersensitivity in postoperative patients compared to preoperative ones. Seven studies suggested that hypersensitivity might cause adverse clinical outcomes, but six did not support any relationship. Seven studies recommended preoperative patch testing in patients with history of metal allergy, and nine concluded that testing may be valuable postoperatively.

Conclusions

Patients undergoing TKA with no prior history of metal hypersensitivity do not seem to be at an increased risk of developing Nickel hypersensitivity, and there is conflicting evidence that patients with pre-existing hypersensitivity are more likely to experience adverse outcomes. Patch testing remains the most commonly used method for diagnosing hypersensitivity, and evidence suggests preoperative testing in patients with history of metal allergy to aid prosthesis selection, and postoperatively in patients with suspected hypersensitivity once common causes of implant failure have been excluded, since revision with hypoallergenic implants may alleviate symptoms.

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.

Lymphocyte Subset Ratio Cannot Diagnose Immune Failure of a TKA

BACKGROUND

Up to 20% of patients are dissatisfied following total knee arthroplasty (TKA), most often due to pain and/or stiffness. The differential diagnosis includes immune reaction to the prosthesis. However, there is no consensus on diagnostic criteria for immune failure, an allergic reaction, to a TKA. Histologic evaluation could provide evidence as to whether an allergic reaction caused TKA failure. A recent study showed an increase in CD4+ lymphocytes compared to CD8+ lymphocytes in patients lymphocyte transformation testing (LTT) + for Ni. This finding is consistent with Ni sensitization, but can lymphocyte subsets be used to diagnose immune failure on a case-by-case basis?

METHODS

Periprosthetic tissues from 18 revision cases of well-fixed, aseptic, but painful and/or stiff primary TKAs were analyzed. Six patients LTT- for Ni were matched as a cohort for age, sex, and body mass index (BMI), to 12 patients LTT + for Ni. Periprosthetic tissue biopsies underwent immunohistochemical IHC staining for CD4+ and CD8+ lymphocyte subsets and were compared by LTT status. The immunohistochemicalIHC results were also compared with periprosthetic histology.

RESULTS

There was no relationship between LTT status and mean CD4+ cells/hpf or CD4+:CD8+ lymphocyte ratio. No relationship was found between LTT stimulation index (continuous or categorical) and CD4+:CD8+ ratio or aseptic lymphocyte-dominant vasculitis-associated lesion ALVAL score.

CONCLUSION

Lymphocytes in periprosthetic tissue are highly variable in number, subtype ratio, and location, and have no relationship to LTT result or ALVAL score on a case-by-case basis. Based on these results, lymphocyte subsets cannot diagnose immune failure. Further work is needed to determine criteria for the diagnosis of immune failure of a TKA.

Nickel-free high-nitrogen austenitic steel outperforms CoCrMo alloy regarding tribocorrosion in simulated inflammatory synovial fluids

CoCrMo alloys are well-established biomaterials used for orthopedic joint replacement implants. However, such alloys have been associated with clinical problems related to wear and corrosion. A new generation of austenitic high-nitrogen steels (AHNSs) has been developed for biomedical applications. Here, we have addressed influences of hyaluronic acid, combined with inflammatory (oxidizing) conditions, on tribocorrosion of the high-nitrogen FeCrMnMoN_0.9 steel (DIN/EN X13CrMnMoN18-14-3, 1.4452), and of the low carbon CoCrMo_0.03 alloy (ISO 5832-12). We aimed to elucidate critical and clinically relevant conditions affecting the implant's performance in certain orthopedic applications. Tribocorrosion tests were conducted in triplicate, with discs under reciprocating sliding wear against a ceramic ball. Different lubricants were prepared from standardized bovine serum solution (ISO 14242-1), with variable additions of hyaluronic acid (HA) and hydrogen peroxide (H₂ O₂ ). Test conditions were: 37°C, 86,400 cycles, 37 N load (20-40 MPa after run-in phase). Volumetric wear was quantified; surfaces were evaluated by electrochemical parameters and microscopy/spectroscopy analyses (SEM/EDS). Factorial analysis of variance tests was conducted to examine the effects of HA, H₂ O₂ , and test material on wear- and corrosion-related dependent variables. Tribocorrosion performances of CoCrMo_0.03 and FeCrMnMoN_0.9 were comparable in fluids without H₂ O₂ . With higher H₂ O₂ concentrations, tribocorrosion increased for CoCrMo_0.03 , while this was not the case for FeCrMnMoN_0.9 . HA significantly enhanced wear of CoCrMo_0.03 in the absence of H₂ O₂ , while it mitigated the tribocorrosive action of 3 mM H₂ O₂ ; HA had no impact on FeCrMnMoN_0.9 . These results indicate a favorable performance of FeCrMnMoN_0.9 compared to CoCrMo_0.03 , and encourage further research on AHNS for certain orthopedic applications.

Similar clinical and radiographic outcomes after two different hypoallergenic medial unicompartmental knee in patients with metal allergy

BACKGROUND

The purpose in the present study was to compare clinical and radiological outcomes of patients who had undergone a mobile-bearing unicompartmental knee arthroplasty (UKA) with either titanium niobium nitride (TiNbN) alloy implants or with fixed-bearing oxidized zirconium alloy implants.

METHODS

The records of two consecutive cohorts for a total of 86 hypoallergenic implants were prospectively analyzed. The first cohort consisted of 49 consecutive implantations of the hypoallergenic UKA Journey Uni Oxinium (Ox Group), while the second consisted of 37 consecutive series of UKA Oxford (TiNbN Group). All patients were evaluated by two independent surgeons who were not involved in the index surgery. The clinical evaluation consisted of evaluating each patient's Oxford Knee Score and Knee Society Score day before surgery (T₀), and with two consecutive follow-ups at T₁ (minimum follow-up 9 months) and T₂ (minimum follow-up 24 months).

RESULTS

The two groups were homogeneous in all preoperative values, except Body Mass Index (BMI) and duration of final follow-up [both statistically higher (p < 0.05) in the TiNbN group]. Both groups showed a clinically significant improvement for all scores at final follow-up (p < 0.05). The only differences between the two groups involved a higher pre-operative Oxford Score in TiNbN group (p = 0.031), and different tibial and femoral angles at the final follow-up.

CONCLUSIONS

Both TiNbN and Oxinium UKA procedures enabled patients from good to excellent clinical and radiographic outcomes after the final follow-up, regardless of the age, gender, BMI bearing type, and implant size.

LEVEL OF EVIDENCE

LEVEL II: Comparative study.

Evaluation of local tissue peri-implant reaction in total knee arthroplasty failure cases

Introduction:

Implant-related hypersensitivity is emerging as a causative factor as a potential source of total knee arthroplasty (TKA) failure. Mechanistically, this type IV hypersensitivity reaction (T4HR) is mediated by effector T-cells, macrophages, and leukocytes that infiltrate to the site of implant and react to metal exposure and induce inflammatory tissue damage.

Methods:

A case–control study was performed where cortical bone was taken at the time of revision surgery for all patients operated on for primary TKA in which metal allergy was suspected and for revision TKA cases done for presumed metal allergy. Cytof was used to determine the cell density of inflammatory cells, specifically Th1, Th2, M1, and M2 cells.

Results:

Comparing the mean cell density of primary versus revision TKA, revision TKA patients had significantly higher number of Th2 cells compared with Th1 cells ( p = 0.0043). Among revision cases, there were significantly more M1 versus M2 macrophages ( p = 0.034) within a patient. When comparing mean cell density of M1 versus M2 macrophages, there was a significant difference in both primary and revision TKA surgeries ( p = 0.0041 primary, p < 0.001 revision). Among revision patients who had a predominance of Th2 cells, four (44%) of nine patients had a negative LTT/patch test.

Conclusion:

These data support metal hypersensitivity, mediated by a T4HR, for some cases of TKA failure. Current methods to screen patients for metal hypersensitivity prior to primary TKA have been inclusive. This study demonstrates the need for a more sensitive screening test from specimens in the knee joint, to more accurately identify patients who will exhibit a T4HR to metal.

Aleaciones metálicas para aplicaciones ortopédicas: una revisión sobre su respuesta al estrés fisiológico y a los procesos de corrosión

El campo de los biomateriales y sus aplicaciones contribuyen significativamente a la salud y calidad de vida de las personas. Aunque existen varios grupos de biomateriales como cerámicos, polímeros, metales y todos en un determinado porcentaje se utilizan para diferentes procedimientos con objetivos específicos, este artículo de revisión se centra en los metales y sus aleaciones, la resistencia de estos a la corrosión en un entorno biológico y la protección contra el estrés fisiológico. Para esta revisión se seleccionaron artículos que permiten describir dichos aspectos de las aleaciones metálicas utilizadas en aplicaciones ortopédicas partiendo de una detallada búsqueda electrónica, a partir de ello, se concluye que la resistencia a la corrosión y el estrés fisiológico son dos aspectos tan neurálgicos que muchas de las investigaciones realizadas tienen como objetivo mejorarlos garantizando el éxito de la osteosíntesis y la recuperación satisfactoria del paciente. The field of biomaterials and their applications contribute significantly to the health and quality of life of people. Although there are several groups of biomaterials such as ceramics, polymers, metals and all of them in a certain percentage are used for different procedures with specific objectives, this review article focuses on metals and their alloys, their resistance to corrosion in a biological environment and protection against physiological stress. For this review, articles were selected to describe these aspects of metal alloys used in orthopedic applications based on a detailed electronic search. From this, it is concluded that resistance to corrosion and physiological stress are two aspects so crucial that many of the researches carried out aim to improve them to ensure the success of osteosynthesis and the satisfactory recovery of the patient.

Impact of Preoperative Metal Patch Testing on Surgery Using Metal Implants

Background

Patients scheduled for metal implant surgery in some facilities in Japan undergo preoperative metal patch testing (MPT). However, few studies have reported the impact of MPT results on scheduled surgery; therefore, the value of preoperative MPT remains unknown.

Material and methods

In analysis 1,the preoperative MPT results requested by orthopedic surgeons from 4 institutions from 2014 to 2018 were retrospectively analyzed. In analysis 2, the medical records of all patients who underwent total hip arthroplasty, total knee arthroplasty, or total shoulder arthroplasty/reverse shoulder arthroplasty between 2014 and 2018 were collected. The number of patients who underwent MPT and their surgical results were analyzed.

Results

In analysis 1, MPT was performed on 72 patients during the study period. The overall MPT positivity rate was 26.4% for the entire cohort in analysis 1. In 4 out of 19 MPT-positive cases, the results of MPT changed the treatment plan to use alternative materials or cancel the surgery. In analysis 2, 1087 patients underwent total hip arthroplasty, total knee arthroplasty, and TSA/RSA; only 16 patients underwent MPT. Aseptic loosening occurred postoperatively in 3 patients (0.3%), none of whom had a history of allergy, and none underwent preoperative MPT.

Conclusion

Metal allergy did not appear to be directly involved in aseptic loosening to any large or meaningful degree in our patient cohort. Only 1.5% of the patients underwent preoperative MPT; therefore, our results suggest this testing had limited benefit or utility. Further studies are needed to determine whether MPT is necessary in preparation for joint replacement.

Is Allergy to Titanium Bone Fixation Plates a Problem?

Open reduction and internal fixation (ORIF) with titanium fixation plates is the gold standard for maxillofacial fracture treatment. Titanium is considered a fully compatible material. However, reports of allergic reactions to titanium implants do occur. The aim of this work is to answer the question whether titanium devices used in the treatment of fractures in the craniofacial region can cause allergic reactions. The study comprised 50 subjects treated surgically for maxillofacial injuries with the use of titanium composite devices. Allergic tests were performed by the patch method. The control group consisted of 20 healthy people who did not have any titanium elements. There were no skin changes to titanium and its compounds in both the test and control groups. Only one patient had a positive skin test which showed an allergic reaction to silver nitrate. Titanium fixing elements, as well as titanium dental implants, according to our research, do not show allergic skin reactions.

Biotribometer for Assessment of Cell and Tissue Toxicity of Orthopedic Metal Implant Debris

A novel approach to address the clinical issue of cell response to wear and corrosion debris from metal orthopedic implants consists of combining cell culturing with wear and corrosion debris generation. A biotribometer equipped with a three-electrode electrochemical chamber operates inside a CO₂ incubator. Cells are cultured at the bottom of the chamber. A ceramic ball (hip implant head) is pressed against a metal disc under a constant load, and set in reciprocating rotation. An anodic electrochemical potential can be applied to a metal disc for accelerated corrosion conditions, or the free potential may be monitored.Measurements of gravimetric and volumetric material loss of the metal disc postwear provide quantitative information that can be put in relation to biological assays (e.g., cell viability and secretion of proinflammatory cytokines). This approach allows for the comparison of candidate metals potentially undergoing tribocorrosion in clinical use. The approach allows to identify the effect of any metastable debris, likely active in vivo.

Synthesis of Fluorinated Polyhydroxyalkanoates from Marine Bioresources as a Promising Biomaterial Coating

By successive enzymatic and chemical modifications, novel fluorinated polyhydroxyalkanoates were synthesized and characterized. Unsaturated polyhydroxyalkanoate, PHAU, was first produced by fermentation using marine bacteria Pseudomonas raguenesii, and a graft copolymer PHAU-g-C₈F₁₇ was further prepared by controlled thiol-ene reaction in the presence of perfluorodecanethiol (PFDT). The PFDT grafting is realized by two different processes. In the first method, PHAU was previously solubilized in toluene. The grafting in solution is more efficient than the direct heterogeneous grafting onto a PHAU film. The degrees of grafting were determined by ¹H NMR. The characterization of the microstructure by SEM-EDX and modulated and conventional DSC showed the formation of microdomains due to the organization of the hydrophobic segments of graft PFDT. Biomaterials prepared by 3D printing and coated by PHAU-g-C₈F₁₇ have the potential to be used as novel contrast agents as shown by Hahn echo experiments.

Case series of metal allergy following Nuss procedure: Not only for stainless steel bars

BACKGROUND

Pectus excavatum is often managed with the Nuss procedure. Metal allergies to pectus bars occur in 5% of patients, though pre-operative testing is not generally routine.

OBJECTIVES

This study describes our experience with pre-operative metal allergy testing and post-operative allergic reactions to pectus bars.

METHODS

A retrospective study of patients who underwent a Nuss procedure at our institution from 2010-2020 was performed. Patients with documented "metal" allergy, defined by the need for and positive response to steroid treatment and the absence of infection, were included. Data on patient characteristics and clinical course were analyzed.

RESULTS

Five of 204 patients (2.5%) identified developed allergic metal reactions. Three of five patients developed allergic reactions to titanium bars, with two requiring early removal of the bar (< 2-3 years). Four patients required more than one course of steroids, and three required debridements for skin breakdown. All patients have maintained good surgical correction at one- and three-years post removal.

CONCLUSIONS

Pectus bar metal allergies occur with both stainless steel and titanium bars. Properly selected patients for pre-operative Finn^Ⓡ Chamber testing may reduce the overall incidence of stainless-steel allergies but may miss titanium bar allergies. Early recognition and treatment of bar allergies may salvage the bar and avoid premature removal.

Can Patients With Metal Hypersensitivity Requiring TMJ Total Joint Prostheses be Successfully Treated With All-Titanium Alloy Mandibular Components?

PURPOSE

Patients with documented metal hypersensitivity to cobalt-chromium-molybdenum (CoCrMo) alloy with trace nickel requiring TMJ total joint prosthesis (TJP) may have adverse reactions to the metals in the standard TMJ Concepts TJP. This study aimed to determine if these patients can be successfully treated by eliminating CoCrMo alloy and constructing the mandibular components of all-titanium (Ti) alloy.

PATIENTS AND METHODS

This retrospective cohort study evaluated metal hypersensitive patients (MHG) that received the TMJ Concepts TJP modification of all-Ti alloy mandibular components with outcome results compared to a control group (CG) of non-metal-sensitive patients that received the standard TMJ Concepts prostheses. The primary predictor variables were the 2 groups, MHG and CG. Primary variables evaluated using Likert scales included TMJ pain, headache, jaw function, diet, and disability. Maximum incisal opening and quality of life were measured. Secondary variables included: age, gender, effect of the number and type of prior TMJ. Scores for pre- and postsurgery parameters (nonparametric variables) were analyzed using a Mann-Whitney U test (α = 0.05).

RESULTS

The MHG (n = 30) received the Ti alloy TJP and CG (n = 46) received the standard TJP, with statistically significant improvements in all variables in both groups and no statistically significant difference in outcome variables between the 2 groups. Patients with 0 to 1 previous TMJ surgeries had better outcomes in all parameters except maximum incisal opening compared to patients with 2 or more previous TMJ surgeries.

CONCLUSIONS

Patients with documented hypersensitivity to CoCrMo alloy, requiring TMJ Concepts TJP may experience improvement in TMJ pain, headache, jaw function, diet, disability, jaw opening, and quality of life when the mandibular components are manufactured from all-Ti alloy, eliminating the CoCrMo alloy. The larger the number of previous TMJ surgeries and exposure to failed alloplastic implants, the less improvement in treatment outcomes.