Abstract
The histology of periprosthetic tissues can often provide clues about the dominant mechanisms of arthroplasty failure. For example, tissue around implants that have developed aseptic loosening associated with particles of wear debris (particle-induced osteolysis) are characterized by infiltrates of macrophages containing phagocytosed debris; lymphocytes are usually not prominent and neutrophils are absent. Although tissues around some failed metal–metal implants show only a macrophage reaction to metal debris and corrosion products (“metallosis”), in other patients periprosthetic tissue has a laminated appearance characterized by superficial necrosis over layers of hyalinized fibrous tissue, diffuse and perivascular chronic inflammation in a pattern thought to represent an immune reaction to metal debris and/or ions (aseptic lymphocyte-dominated vasculitis-associated lesion, ALVAL). Some of these findings are also seen in hips that have been treated for infection, but neutrophils are not a feature of ALVAL. Whether or not periprosthetic tissue shows features suggestive of particle-induced osteolysis or ALVAL, five or more neutrophils in each of five or more high-magnification visual fields suggest coexisting infection. Additional studies are needed to define the histologic characteristics of periprosthetic soft tissue masses (pseudotumors), cysts, and other adverse events.
Published Version
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