INFECTION AFTER EXTENSIBLE ENDOPROSTHETIC REPLACEMENTS FOR BONE TUMOURS

Abstract

The purpose of this retrospective study was to analyze the risk factors, causes, bacteriology of deep infection following extensible endoprosthetic replacement for bone tumours in children and to review our experience in the treatment of 20 patients with infected prostheses.

123 patients with extensible endoprostheses were treated between 1983 and 1998. Three types of prostheses, which differed in the lengthening mechanism used, were implanted. 20 of these were diagnosed to have deep infection. Patients were divided into 3 groups: group I 5 patients were treated with a single stage revision, group 11– 13 patients were treated with a two stage revision procedure, group Ill- 2 patients had a primary amputation. Control of infection was assessed clinically and with inflammatory markers. Function was assessed using the MSTS score.

The overall incidence of infection was 16%. The incidence of infection at the proximal tibia and distal femur was 27% and 14% respectively. Staphylococcus epidermidis was the most common organism. The most common clinical features were pain and swelling around the prostheses. Infection in most cases was immediately preceded by an operative procedure or by distant a focus of infection. The number of operative procedures and the site of the prosthesis were significant risk factors. The success rate was 20% in Group 1 and 84% in Group II. Amputation was the salvage procedure of choice for failed revision procedures. The mean MSTS functional score was 83% in patients in whom the infection was controlled.

The incidence of deep infection is high following extensible endoprostheses. The site of the prosthesis and the number of operative procedures are significant risk factors. The type of prosthesis used is not a risk factor. Two-stage revision is successful in controlling infection in a majority of these cases.