Exploring the Incidence, Implications, and Relevance of Metal Allergy to Orthopaedic Surgeons

Existing and Novel Assessment Methods for Metal Sensitivity in Elective Lower-Limb Arthroplasty-A Scoping Review

Background

Metal sensitivity is a possible cause for revision in elective lower-limb arthroplasty. This scoping review aims to identify and evaluate all existing and novel assessment methods for metal sensitivity in elective lower-limb arthroplasty.

Methods

The Cochrane Central Register of Controlled Trials (CENTRAL), Ovid Medical Literature Analysis and Retrieval System Online (MEDLINE), PubMed, and Google Scholar databases were searched for studies published between January 1, 2000, and September 1, 2023. Studies evaluating one or more metal sensitivity assessment method preoperatively, perioperatively, or postoperatively were included. Studies were grouped based on the assessment methods reported and summarized based on the study design, outcome measure, results, and comments on the method's validity.

Results

A total of 1220 results were screened, with 39 results (15 retrospective cohort studies, 11 prospective cohort studies, 6 case reports, 5 randomized controlled trials, and 2 case control studies) included, identifying 12 assessment methods. The most used one was patch testing, featuring in 17 studies (43.6%). Lymphocyte transformation assay/testing featured in 12 studies (30.8%). Plasma/serum concentration of metal ions featured in 6 studies (15.4%). Patient history and serum cytokine testing featured in 7 (17.9%) and 4 (10.3%) studies each. Generalized serum inflammatory markers featured in 3 studies (7.7%). The remaining 6 methods each featured in one or 2 studies. Evidence of the reliability of most metrics was limited.

Conclusions

Several assessment methods were identified. However, evidence of any methods reliably predicting and diagnosing the occurrence of metal sensitivity was limited. There is a need for improved metrics of metal hypersensitivity.

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.

Plastic response of macrophages to metal ions and nanoparticles in time mimicking metal implant body environment

The paradigm of using metal biomaterials could be viewed from two sides - treatment of wide spectrum of degenerative diseases, and debris release from materials. After implant insertion, metal nanoparticles (NPs) and ions are released not only upon the first contact with cells/tissues, but in continual manner, which is immediately recognized by immune cells. In this work, the effects of metal nanoparticles (TiO2, Ni) and ions (Ni2+, Co2+, Cr3+, Mo6+) on primary human M0 macrophages from the blood samples of osteoarthritic patients undergoing total arthroplasty were studied in order to monitor immunomodulatory effects on the cells in a real-time format. The highest NiNPs concentration of 10 µg/ml had no effect on any of macrophage parameters, while the Ni2+ ions cytotoxicity limit for the cells is 0.5 mM. The cytotoxic effects of higher Ni2+ concentration revealed mitochondrial network fragmentation leading to mitochondrial dysfunction, accompanied by increased lysosomal activity and changes in pro-apoptotic markers. The suppression of M2 cell formation ability was connected to presence of Ni2+ ions (0.5 mM) and TiO2NPs (10 µg/ml). The immunomodulatory effect of Mo6+ ions, controversially, inhibit the formation of the cells with M1 phenotype and potentiate the thread-like shape M2s with increased chaotic cell movement. To summarize, metal toxicity depends on the debris form. Both, metal ions and nanoparticles affect macrophage size, morphological and functional parameters, but the effect of ions is more complex and likely more harmful, which has potential impact on healing and determines post-implantation reactions.

Endovascular Treatment of Cerebrovascular Lesions Using Nickel- or Nitinol-Containing Devices in Patients with Nickel Allergies

Nickel is used in many cerebral endovascular treatment devices. However, nickel hypersensitivity is the most common metal allergy, and the relative risk of treatment in these patients is unknown. This retrospective analysis identified patients with nickel or metal allergies who underwent cerebral endovascular treatment with nickel-containing devices. Seven patients with nickel and/or other metal allergies underwent treatment with 9 nickel-containing devices. None experienced periprocedural complications. No patient received treatment with corticosteroids or antihistamines. At a mean clinical follow-up for all patients of 22.8 months (range, 10.5-38.0 months), no patients had symptoms attributable to nickel allergic reactions. The mean radiographic follow-up for all patients at 18.4 months (range, 2.5-37.5 months) showed successful treatment of the targeted vascular pathologies, with no evidence of in-stent stenosis or other allergic or hypersensitivity sequelae. The treatment of cerebrovascular lesions with a nickel-containing device resulted in no adverse outcomes among these patients and was safe and effective.

Diagnosis and Management of a Hypersensitivity Reaction to Titanium-Containing Surgical Clips: A Case Report

Although titanium allergies are not commonly diagnosed, they can present with a variety of conditions years after the implantation of titanium-containing medical devices. Furthermore, there are few options to effectively manage the long-term outcomes of these conditions. We present the case of a 41-year-old female who experienced neck swelling, pain, and difficulty swallowing 16 years after a right thyroid lobectomy for benign follicular adenoma, requiring the implantation of titanium-containing surgical clips in her neck. This was accompanied by an extensive symptomatic history, and the patient showed mild reactivity to nickel and titanium on a metal lymphocyte transformation test analysis. X-ray and computed tomography of the neck later confirmed the location of 18 surgical clips. The patient was diagnosed with a chronic immune disease including immune complex disease and mast cell activation-related symptoms. Symptoms were managed with low-dose naltrexone until the surgical clips were removed. Further research is needed to identify more accurate testing methods to diagnose titanium hypersensitivity. Alternative treatment methods should be explored to reduce disease burden and complications related to titanium-containing implants.

Preliminary Study on Immediate Postoperative CT Images and Values of the Modular Polyetheretherketone Based Total Knee Arthroplasty: An Observational First-in-Human Trial

BACKGROUND

Total knee arthroplasty (TKA) is now frequently performed and is highly successful. However, patient satisfaction after TKA is often difficult to achieve. Because of the presence of metallic prosthetic knee joints, there is a lack of imaging tools that can accurately assess the patient's postoperative prosthetic position, soft tissue impingement, and periprosthetic bone density after TKA. We conducted a clinical trial of the world's first totally modular polyetheretherketone (PEEK) TKA and determined the bone density values in the stress concentration area around the prosthesis based on postoperative computed tomography data to reconstruct a three-dimensional model of the PEEK prosthetic knee joint after implantation. Based on the model, the overhang of the prosthesis was measured at various locations on the prosthesis.

METHODS

All patients who underwent PEEK-based TKA were postoperatively assessed with radiography and computed tomography (CT). Hounsfield units (HUs) for the different components of the quantitative CT assessment were measured separately.

RESULTS

Ten patients (nine female and one male) aged 59-74 (mean 66.9, median 67) years were included. The HU values were as follows: PEEK prosthesis mean 182.95, standard deviation (SD) 4.90, coefficient of variation (CV) 2.68; polyethylene mean -89.41, SD 4.14, CV -4.63; lateral femoral osteochondral mean 192.19, SD 55.05, CV 28.64; lateral tibial osteochondral mean 122.94, SD 62.14, CV 42.86; medial femoral osteophyte mean 180.76, SD 43.48, CV 24.05; and medial tibial osteophyte mean 282.59, SD 69.28, CV 24.52. Analysis of the data at 1, 3, and 6 months showed that the mean PE (p = 0.598) and PEEK (p = 0.916) measurements did not change with the time of measurement. There was a decrease in bone mineral density in the lateral tibia at 3 months (p = 0.044). Otherwise, there was no significant change in bone density in other regions (p = 0.124-0.803). There was no overhang in all femoral prostheses, whereas there were two cases of overhang in tibial prostheses. Overhang measurements do not differ significantly across time points. The overhang measurements were not significantly different at all time points (p = 0.186-0.967).

CONCLUSION

PEEK knee joint prosthesis has excellent CT compatibility. The change in periprosthetic bone volume during the follow-up period can be determined using the HU value after CT scan, while the prosthesis position can be assessed. This assessment may potentially guide future improvements in knee prosthesis alignment techniques and artificial knee prosthesis designs.

Immunological Mechanisms of Metal Allergies and the Nickel-Specific TCR-pMHC Interface

Besides having physiological functions and general toxic effects, many metal ions can cause allergic reactions in humans. We here review the immune events involved in the mediation of metal allergies. We focus on nickel (Ni), cobalt (Co) and palladium (Pd), because these allergens are among the most prevalent sensitizers (Ni, Co) and immediate neighbors in the periodic table of the chemical elements. Co-sensitization between Ni and the other two metals is frequent while the knowledge on a possible immunological cross-reactivity using in vivo and in vitro approaches remains limited. At the center of an allergic reaction lies the capability of a metal allergen to form T cell epitopes that are recognized by specific T cell receptors (TCR). Technological advances such as activation-induced marker assays and TCR high-throughput sequencing recently provided new insights into the interaction of Ni2+ with the αβ TCR-peptide-major histocompatibility complex (pMHC) interface. Ni2+ functionally binds to the TCR gene segment TRAV9-2 or a histidine in the complementarity determining region 3 (CDR3), the main antigen binding region. Thus, we overview known, newly identified and hypothesized mechanisms of metal-specific T cell activation and discuss current knowledge on cross-reactivity.

The Allergic Bone Marrow? The Immuno-Capacity of the Human Bone Marrow in Context of Metal-Associated Hypersensitivity Reactions

Arthroplasty ranks among the greatest achievements of surgical medicine, with total hip replacement termed “the operation of the century.” Despite its wide success, arthroplasty bears risks, such as local reactions to implant derived wear and corrosion products. Prevalence of allergies across Western society increases and along the number of reported hypersensitivity reactions to orthopedic implant materials. In this context the main focus is on delayed hypersensitivity (DTH). This mechanism is mainly attributed to T cells and an overreaction of the adaptive immune system. Arthroplasty implant materials are in direct contact with bone marrow (BM), which is discussed as a secondary lymphoid organ. However, the mechanisms of sensitization toward implant wear remain elusive. Nickel and cobalt ions can form haptens with native peptides to activate immune cell receptors and are therefore common T helper allergens in cutaneous DTH. The rising prevalence of metal-related allergy in the general population and evidence for the immune-modulating function of BM allow for the assumption hypersensitivity reactions could occur in peri-implant BM. There is evidence that pro-inflammatory factors released during DTH reactions enhance osteoclast activity and inhibit osteoblast function, an imbalance characteristic for osteolysis. Even though some mechanisms are understood, hypersensitivity has remained a diagnosis of exclusion. This review aims to summarize current views on the pathomechanism of DTH in arthroplasty with emphasis on BM and discusses recent advances and future directions for basic research and clinical diagnostics.