This 2001 Current Concepts Review from JBJS synthesizes the biology, testing methods, and clinical evidence around metal sensitivity in orthopedic implant patients. It asks whether immune reactions to corrosion products cause implant failure, result from it, or simply co-exist. No causal direction is established, but the association between failed implants and metal sensitivity is striking.
A patient returns six months after total hip arthroplasty with generalized eczema, urticaria, or unexplained implant loosening. The first instinct is infection — but metal hypersensitivity belongs on your differential, and roughly 60% of patients with failed implants carry some degree of metal sensitivity.
When you evaluate these patients, reach for LTT rather than relying on patch testing alone. Patch testing is the more familiar test, but it is less sensitive for implant-related reactions, uses exposure conditions that do not mirror the periprosthetic environment, and carries a small risk of actually inducing sensitivity in a previously negative patient.
For preoperative counseling: a patient who reacts to jewelry or has a documented prior reaction to a metallic device warrants consideration of alternative alloy selection. A patient with only a positive patch test and no clinical reaction history does not require a change in implant selection based on current evidence.
This paper also established why metal-on-metal bearings are scrutinized more heavily than metal-on-polyethylene designs. Greater metal ion release correlates with greater sensitization rates, a principle that shaped the subsequent regulatory and clinical response to metal-on-metal hip arthroplasty failures.
This 2001 Current Concepts Review from JBJS synthesizes the biology, testing methods, and clinical evidence around metal sensitivity in orthopedic implant patients. It asks whether immune reactions to corrosion products cause implant failure, result from it, or simply co-exist. No causal direction is established, but the association between failed implants and metal sensitivity is striking.
A patient returns six months after total hip arthroplasty with generalized eczema, urticaria, or unexplained implant loosening. The first instinct is infection — but metal hypersensitivity belongs on your differential, and roughly 60% of patients with failed implants carry some degree of metal sensitivity.
When you evaluate these patients, reach for LTT rather than relying on patch testing alone. Patch testing is the more familiar test, but it is less sensitive for implant-related reactions, uses exposure conditions that do not mirror the periprosthetic environment, and carries a small risk of actually inducing sensitivity in a previously negative patient.
For preoperative counseling: a patient who reacts to jewelry or has a documented prior reaction to a metallic device warrants consideration of alternative alloy selection. A patient with only a positive patch test and no clinical reaction history does not require a change in implant selection based on current evidence.
This paper also established why metal-on-metal bearings are scrutinized more heavily than metal-on-polyethylene designs. Greater metal ion release correlates with greater sensitization rates, a principle that shaped the subsequent regulatory and clinical response to metal-on-metal hip arthroplasty failures.