Abstract
Introduction
Various anti-infective agents can be added to the surface of orthopaedic implants to actively kill bacteria and prevent infection. Silver (Ag) is a commonly used agent in various anti-infective applications. Silver disrupts bacterial membranes and binds to bacterial DNA and to the sulfhydryl groups of metabolic enzymes in the bacterial electron transport chain, thus inactivating bacterial replication and key metabolic processes. Recently we are implanting Silver coated megaprosthesis for the treatment of post-traumatic septic non unions/bone defects and for infected hip or knee prosthesis revision. We treat these complications utilizing a two steps procedure: 1° step: devices removal, resection, debridment and antibiotic spacer implantation; 2° step: spacer removal and megaprosthesis implantation. This technique produce a reactive pseudosynovial membrane, well known in traumatology (Masquelet technique), following the Chamber Induction Technique principles. This chamber creates the perfect environment in which implant the prosthesis with safety. We are nowadays investigating if this membrane could optimize the Silver antimicrobical effects reducing the Silver ions dispersion and reducing toxicity on the human body.
Objectives
The aim of this study is to perform a review of the literature about Silver coated implants in Orthopaedics and Trauma and to analyze our cases treated with this implants in order to measure their efficacy and the ion dispersion in urine and blood.
Methods
We performed a literature review using the universally validated search engines in the biomedical field: PubMed / Medline, Google Scholar, Scopus, EMBASE. The keywords used were: “Silver”, “Silver coating”, “Silver surface”, “were crossed with “Prosthesis”, “Megaprosthesis”, “Infection”, “Sepsis”, “Revision”. We also analized all our patients treated with Silver coated implants measuring Silver dose in blood and urine before implantation, 1 day after implantation and then after 15 days, 3,6,12,24,36 months.
Results
The search led to 468 items, of these were considered only article in English with full text available. We found 1 in vitro study, 1 animal study and 2 human studies.
The animal study showed a reduction in periprosthetic infection from 47% to 7%, 1 human study in Oncology application of megaprosthesis showed a reduction of septic complications from 17,6% to 5,9%. Te other human study demonstrated that Silver surface implants don't have toxicity cause the blood level of silver Ions were only 56,4 parts per billion. The analysis of our casuistry is giving good results with low level of Silver in the blood and urine, lower concentrations are observed in patients treated with the 2 steps-CIT technique.
Conclusions
The use of silver-coated prosthesis can reduce the infection rate in the medium-long term with no toxicity for the patients. Further studies with longer term follow-up periods and larger numbers of patients are warranted in order to confirm these encouraging results most of all in the patients treated with the 2 steps procedure in order to better understand the role of the membrane and of the Chamber Induction Technique in Silver ions dispersions.
