Introduction:
Increased knowledge of a patient's history of hypersensitivity may help shield them from implants that include metals that can trigger hypersensitivity. Patients and surgeons may have concerns regarding metal allergies. Patients with verified or suspected metal hypersensitivity may be candidates for non-metal-containing or nonreactive metal implants.
Metal hypersensitivity is estimated to affect 10 to 15 percent of the general population. Orthopedic surgery commonly uses metal implants. Given its frequency in the population and the increased prevalence of metal hypersensitivity identified in patients with failed surgical implants, a portion of surgical difficulties may be related to metal hypersensitivity.
Why Is Metal Hypersensitivity Experienced After a Surgery?
The vast majority of orthopedic implants are made of metal. Most of these implants are constructed of alloy metals, which contain various proportions of metals to which individuals have hypersensitivity, such as nickel, cobalt, and chromium. The pathophysiology of metal hypersensitivity-related problems is poorly understood and potentially complex. It is thought to be linked to the individual's T-cell immunological state, the reactivity of specific metal ions with HLA antigen and other proteins, and the metals' corrosive and dispersive qualities.
Cutaneous or systemic responses have been linked to metal allergy in orthopedic surgery. The most typical presentation is eczematous-like rashes covering metallic hardware (type IV delayed hypersensitivity). Reactions involving titanium, nickel, and chromium are common. Besides infection and implant wear, metal hypersensitivity can be diagnosed after surgery.
How Is Metal Hypersensitivity Testing Performed?
Although patch testing is commonly carried out with a specified standard series of metals, it is still being determined if it helps identify and treat metal hypersensitivities. Leukocyte migration inhibition testing (LMIT) and lymphocyte transformation testing (LTT) are further in-vitro diagnostic assays. While LTT gauges the number of T cells that proliferate after exposure to an allergen, LMIT evaluates the extent of lymphocyte migration in reaction to an allergen.
Compared to traditional patch testing, LTT and LMIT offer greater specificity but lower sensitivity and higher costs. Today, no recognized procedure exists for diagnosing and treating patients experiencing metal hypersensitivity reactions following foot or ankle surgery. Similarly, there are no rules from a regulatory body or orthopedic society to identify patients at risk before surgery.
What Are the Signs of Metal Sensitivity Before Surgery?
If an individual has experienced skin responses to eyeglasses or jewelry, this may indicate sensitivity to metals. Before the surgery is planned, discuss these reactions with the surgeon. Additionally, certain persons who handle or are around specific metals may become sensitive to those metals. In either scenario, if specific, non-allergic implants are available, the surgeon will opt for them.
The research has had substantial discussion regarding metal hypersensitivity to orthopedic implants and the associated consequences. Similar reactions to metallic orthopedic implants are far less prevalent despite reports of cutaneous reactions after skin contact with metal objects being relatively widespread.
A 1966 case report by Foussereau and Laugier described a patient with eczematous dermatitis at the site of a metallic plate used for fracture fixation, the first documented instance of cutaneous hypersensitivity brought on by a metallic orthopedic implant. Subsequently, numerous case reports, including orthopedic, dental, plastic surgery, and cardiovascular, have detailed comparable skin reactions to metallic implants. Additional possible signs of metal hypersensitivity from implants include discomfort, effusions, infection-mimicking reactions, slowed wound healing, and implant loosening.
Orthopedic implant metal debris has been isolated in blood and lymph samples and discovered in patients' soft tissues and synovial fluid who use metal prostheses. T-mediated type IV hypersensitivity has been identified as the most prevalent hypersensitivity associated with total joint replacement (TJR). Documentation of T and B lymphocyte infiltrates in soft tissue following hardware explantation suggests an immunological response to the implant.
Metal hypersensitivity frequently emerges as contact dermatitis on metal-exposed skin; however, metallic orthopedic implants are implanted deep within the tissue and away from the surface. These metals might sensitize the body and cause an immunological response. Systemic contact dermatitis (SCD) refers to a condition where an individual who is sensitized to an allergen via the cutaneous route will subsequently react to that same allergen or a cross-reacting allergen via the systemic route (oral, intravenous, intramuscular, inhalational, transmucosal, or transcutaneous).
This secondary reaction can manifest as a skin reaction such as dermatitis, urticaria, bullous reactions, vasculitis, or impaired wound healing at the site of the initial reaction or elsewhere, or it may be related to the type IV delayed hypersensitivity reaction occasionally observed in the periprosthetic tissues of metallic implant recipients.
Recently, the possible influence of metal hypersensitivity on TJR was reported. Research has examined patient-reported metal hypersensitivity to various metals and their consequences on physical function, pain, systemic symptoms, and mental health for lower-extremity TJR. Patient reports of metal hypersensitivity have been extensively researched in lower-extremity TJR, but there is limited data on total shoulder arthroplasty. Contact dermatitis and widespread pruritus are common clinical signs of skin hypersensitivity.
How to Manage Metal Hypersensitivity After Surgery?
The relationship between reported symptoms, particularly non-skin-related somatic symptoms and pain and metal hypersensitivity in individuals with metal implants, is not well established.
There is no consensus or standard on how to screen or what changes in treatment plans should be made when delayed-onset T-cell-mediated metal hypersensitivity is suspected or confirmed. Although there is inconclusive data about the significance of metal hypersensitivity in persistently painful or aseptic loosening of arthroplasties, studies indicate that preoperative testing may alter surgical management.
Conclusion:
T-cell-mediated delayed-onset metal hypersensitivity in orthopedic surgery patients can be an issue for both surgeons and patients. More research is needed to demonstrate a link between metal hypersensitivity and the likelihood of problems in metallic implant procedures. An increased understanding of metal hypersensitivity may limit patient exposure to implants containing metals to which they may react. Non-metal-containing or nonreactive metal implants are an alternative for people with metal hypersensitivity, whether suspected or verified. Orthopedic doctors may also benefit from investigating hypersensitivity to bone cement.
