Orthopedic Implant Hypersensitivity Reactions: Concepts and Controversies

Orthopedic implant hypersensitivity reactions (IHRs) are known to occur but are uncommon. Clinical presentations include local and generalized cutaneous reactions and noncutaneous complications. Pathogenesis traditionally was believed a type IV delayed hypersensitivity reaction, but there is evidence that innate immunity plays a role. Orthopedic implants are made predominantly of metals, and nonmetal components, such as bone cement, plastics, and ceramics, also may be utilized. Several diagnostic tests are available, and patch testing is considered the gold standard. Diagnostic criteria for IHRs have been developed and can help with determination as to whether orthopedic implant symptoms are due to IHRs.