Tissue reaction around loosened prostheses: a histological, X-ray microanalytic and immunological study.

Tissue reactions at the cement-bone and artificial implant-bone interface were examined light and electron microscopically in thirty-six patients who underwent revisory operation of hip or knee replacement. The reactions were classified into three types: inert tissue, active tissue with giant cell proliferation, and active tissue with predominant foamy cell proliferation. The third type of reaction was found only in total hip replacement with bone cement. No evidence of allergic reaction to implanted materials was found in any replacement, though active cellular infiltrations were observed around loosened prostheses especially in cemented arthroplasty. The tissue reactions always occurred around instable or loosened prostheses. Thus, the present study shows that mechanical instability is the primary cause of such undesired tissue reactions.