[Infected total knee prosthesis. Guidance for therapeutic choice].

PURPOSE OF THE STUDY: The aim of the study is to assess the functional results and septic evolution in the treatment of infected total knee arthroplasties.

MATERIAL AND METHODS: 22 patients were reviewed; 8 were initially treated in our institution and 14 transferred from other hospitals. Articular debridement alone leaving the prosthesis in situ was initiated in 3 of our 8 patients as well as in 6 of the transferred cases. In both groups, this procedure appeared to be a failure. Prosthetic-reimplantation procedure was elected in 10 patients either as a one-stage (5 cases) or a two-stage surgery (5 cases). This has been successfully rated in 7 cases. Femoro-tibial arthrodesis was performed in 15 patients, three of them being a failure of the prosthetic reimplantation. Follow-up ranges from 16 months to 9 years with well documented records.

RESULTS: As stated earlier, articular debridement alone has not proven to be a helpful procedure since it did not eradicate the septic complication in any case. Prosthetic reimplantation has been a successful treatment in 7 of the 10 attempted cases. The one-stage procedure is providing the best functional result. Recurrent infection occurred in 3 cases: there were patients with poor host defense (diabetes, arteritis, old age, ...) with resistant bacteria complicating a hinge-knee prosthesis. Femoro-tibial arthrodesis was achieved in 10 of the 15 patients and necessitated all together 23 surgical operations. The highest union rate was observed in cases where sterile conditions were achieved, fixation being performed with an intramedullary nail. Failure of arthrodesis confines the patients in such an uncomfortable situation that 2 of them has asked for an amputation.

DISCUSSION AND CONCLUSION: Early surgical debridement may occasionally salve a prosthesis when it is performed shortly after the onset of infection, in an unloosened unconstrained prosthesis infected by a low-virulence organism. In our study, no patient but one met those criteria. For those cases nevertheless, our procedure of choice is now the one-stage reimplantation who seems to be more effective for eradicating the infection and gives rise to a better clinical result. The two-stage reimplantation is the current procedure for handling an infected knee prosthesis. Some patients are still excluded from this procedure because of their poor health condition, bone loss, inadequate viability of skin and extensor mechanism or an uncontrolled sepsis. For such a case, arthrodesis remains the most reliable method of management, especially when it can be stabilized with an intramedullary fixation, which implies to perform a two-stage arthrodesis.