S08.3 INCIDENCE, TREATMENT AND OUTCOME OF INFECTION IN PROSTHETIC RECONSTRUCTIONS OF THE HUMERUS AFTER RESECTION OF BONE TUMORS.

Abstract

Objective: Aim of this study was to analyse the incidence of infections in primary prosthetic reconstructions of the humerus after resection for bone tumours and their treatment and results.

Material and Methods: Between 1974 and 2006 at Rizzoli 344 reconstructions of the humerus using prosthetic devices (alone or in association with allografts) were performed. Sites of reconstruction were: proximal humerus 311, distal humerus 19, diaphysis 5, total humerus 9. Histological diagnoses included 24 benign tumors, 253 malignant tumors and 67 metastatic carcinomas. Patients were followed periodically in the clinic. Informations were obtained from clinical charts and imaging studies with special attention to major complications requiring revision surgery. Univariate analysis through Kaplan-Meier actuarial curves was used in evaluating implant survival to major complications. Infections developing in the first 4 weeks were considered postoperative infections, those diagnosed in the first 6 months were judged early infections, while late infections those diagnosed after 6 months from surgery.

Results: In 20 patients (5.8%) a revision for deep infection was required. In 19 of these cases tumor was localized in the proximal humerus and in 1 in the distal humerus. There were 18 infections in prostheses and 2 in allograft prosthesis composites. Two infections were postoperatively diagnosed, seven were early infections and eleven late infections. Revision was required in 18 cemented prosthesis, 1 uncemented prostheses and 1 Coonrad-Morrey.

S. Epidermidis and S. Aureo were the most frequent bacteria causing infection (45%). Two stage treatment of infection was chosen: removal of the implant and temporary substitution with cement spacer with antibiotics (usually vancomycin) until infection healed. But a new prostheses was actually implanted in 3 cases only (at mean time of 5.7 mos), while in 17 the spacer was never removed by patients choice due to the acceptable result with the spacer. Systemic antibiotics were associated according to cultural results. Infection healed in all patients.

Conclusions: Infection is the most severe complication in prosthetic reconstructions for tumours of the humerus. Its incidence (5.8%) is lower than in lower limb. Treatment requires a team work: surgeon, microbiologist and infectious disease physician. One stage is indicated in postoperative infections, two stage is recommended in both early and late infections. Two stage surgery offered good results, although in most cases a new prosthesis was not implanted, since actually humeral megaprostheses act as a spacer and don’t provide a much better function.