Infection after total knee prosthesis - The surgeon's point of view

Summary

Infection of a knee prosthesis leads to specific problems in relation to the function of the knee joint and its superficial location in comparison with the better known infection after total hip replacement. Every joint replacement is a foreign body which promotes a reaction of the host organism. The important and dangerous period for infection is the initial period after foreign body implantation, until all its adherence receptors are inactivated by the normal biological host response. The presence of a foreign body decreases the local immune response of the host, and especially the phagocytosis mechanisms and antibiotic effectiveness, due to anaerobic conditions. The surgical debridement of a joint prosthesis is ineffective because it is unable to debride the prosthesis-host interface, which is always contaminated in a per-operatively acquired infection. The only effective treatment is then removal of the foreign body. Results of the treatment of infected knee arthroplasties are very different in the literature. Medical treatment alone, surgical debridement alone, arthrodesis or amputation should only be used in cases where the optimal treatment, i.e. one or two-stage exchange, is contra-indicated. There is no evidence for the superiority of one or two-stage exchange in curing infection, but the functional results of the former treatment should be better. The choice of the prosthesis must be made on mechanical considerations only, as for aseptic revisions. Primary fixation is mandatory, and cemented fixation often offers the best cost-benefit ratio.