TREATMENT STRATEGIES FOR INFECTED MEGAPROSTHESIS

Abstract

Infection of a megaprosthesis implanted following tumor resection leads to major morbidity and sometimes amputation. Their treatment is like treatment of infected total knee or hip prosthesis, except there is a dramatically larger dead or infected tissue, and immune deficiency due to oncologic treatments. Two-stage revision of infected megaprosthesis seems to be the safest solution except amputation.

Between 1990–2005, we have implanted 282 megaprosthesis in the upper and lower extremity following tumor resection. Sixteen prostheses became infected after a median of 48 months (2–96) following the index intervention. All of them underwent two-stage revision. The infections were staged after Mc Pherson classification, revealing that 75% of them were ‘stage IIIB’. The first stage included debridement, insertion of culture specific antibiotic-loaded bone cement in the form of beads and/or rods, temporary fixation with a custom made IM nail or self-designed, mobile hinged-joint prosthesis covered with antibiotic- loaded PMMA. The most common grown microorganism was MRSA. Following parenteral antibiotherapy, the second staging was performed after a median of 6 weeks (5–11). The reconstruction stage included reimplantation of a cemented prosthesis in 5 patients, a cemented prosthesis in 6 patients, arthrodesis through segment transfer with an external fixator in 4 patients. Eight patients necessitated a local or a distant flap for soft tissue coverage. A patient with recurrent deep infection was amputated.

Patients were followed up for a median of 86 months (24–146). Infection was controlled in 15 patients, with an overall success rate of 94%. The mean functional outcome for the retained limb using the MSTS score was 70%.

Two-stage revision in infected mega prosthesis yields results close to conventional joint replacements, if general guidelines are followed and good soft tissue coverage is provided.