These devices are not cleared by the FDA for use in the US.
The antimicrobial properties of silver are well-documented1,2,3,4 and silver is integrated into many types of medical devices including catheters, vascular prostheses and bandages. Pairing megaprostheses with silver is an ideal combination for high risk tumor and advanced revision procedures which run a 5-35% infection risk5,6. Infection following megaprosthesis procedures is one of the leading causes of failure for these devices7,8 and also places a significant burden on the healthcare system from a cost perspective. Reducing the infection rate is of the utmost priority for these patients whose alternative in many cases is amputation.
The Intelligent Effect
Implant-associated infections are the result of adhered bacteria and consequent biofilm formation on the surface of the implant. In cooperation between implantcast GmbH and the University of Münster, silver is used in the MUTARS megaprosthesis system to build a long term prophylaxis against the colonization of these pathogenic bacteria. Metallic silver is oligodynamic and allows a sustained release of silver ions over time9. Based on the sustained release, silver is especially suitable for biofilm inhibition and thus long-term prevention of late implant infections9. This is a major advantage compared to silver salts that are often used in other medical applications which dissolve much faster.
Several studies with silver-coated tumor megaprosthesis demonstrate the proven effect against a wide spectrum of bacteria and fungi9 and thus a highly promising infection prophylaxis:
Hardes J, Ahrens H, Gebert C, Streitbuerger A, Buerger H, Erren M, Gunsel A, Wedemeyer C, Saxler G, Winkelmann W, Gosheger G. Lack of toxicological side-effects in silver-coated megaprostheses in humans. Biomaterials, 2007 - 28(18):2869-75.
Investigation of silver-related side effects in 20 patients who had been treated with a silver-coated MUTARS® tumor endoprosthesis
- A highest single value of serum silver concentration of 56.40 ppb and a highest single value for the silver concentration in the urine of 43.40 ppb were reported, which can be considered as non-toxic
- Clinical examination revealed in no patient any signs of local or systemic side-effects
Hardes J, von Eiff C, Streitbuerger A, Balke M, Budny T, Henrichs MP, Hauschild G, Ahrens H. Reduction of Periprosthetic Infection With Silver-Coated Megaprostheses in Patients With Bone Sarcoma. J Surg Oncol. 2010 Apr 1; 101(5):389-95. doi: 10.1002/jso.21498.
The infection rate in 51 patients with sarcoma (proximal femur, n=22; proximal tibia, n=29) who underwent placement of a silver-coated MUTARS® megaprosthesis was assessed prospectively over a 5-year period, along with the treatment administered for infection. The infection rate was compared with the data for 74 patients in whom an uncoated titanium megaprosthesis (proximal femur, n=33; proximal tibia, n=41) was implanted.
- “The infection rate was substantially reduced from 17.6% in the titanium to 5.9% in the silver group. Whereas 38.5% of patients in the titanium group ultimately had to undergo amputation when periprosthetic infection developed, these mutilating surgical procedures were not necessary in the study group”
- “The use of silver-coated prostheses reduced the infection rate in the medium term. In addition, less aggressive treatment of infection was possible in the group with silver-coated prostheses”
Hussmann B, Johann I, Kauther MD, Landgraeber S, Jäger M, Lendemans S. Measurement of the silver ion concentration in wound fluids after implantation of silver-coated megaprostheses: correlation with the clinical outcome. Biomed Res Int. 2013; 2013:763096.
- Fewer reinfections and shorter hospitalization times could be demonstrated in 18 patients which had been treated with a silver-coated MUTARS® endoprosthesis. One of 18 patients (5.6%) showed a reinfection within the 12 months post-surgery as compared to 7 out of 31 patients (22.6%) in the retrospective group with the same indication megaprosthesis without silver.
- No toxic side effects were detected during a 12 months follow up period. Chemical laboratory analyses that were conducted during routine checks did not indicate any silver intoxication, neither could indications of silver intoxication be proven clinically.
Gosheger G, Hardes J, Ahrens H, Streitburger A, Buerger H, Erren M, Gunsel A, Kemper FH, Winkelmann W, Von Eiff C. Silver-coated megaendoprostheses in a rabbit model--an analysis of the infection rate and toxicological side effects. Biomaterials. 2004 Nov;25(24):5547-56.
30 rabbits received MUTARS® endoprostheses (15 titanium and 15 silver-coated) and were infected with Staphylococcus aureus for evaluation. Additionally, toxicological side effects were analyzed in 10 of those rabbits with a silver-coated megaprosthesis.
- “The silver group showed significantly lower infection rates (7% versus 47%) in comparison with the titanium group. Measurements of the C-reactive-protein, neutrophilic leukocytes, rectal temperature and body weight showed significant lower signs of inflammation in the silver group.”
- “The analysis of the silver concentration in blood and in organs showed elevated silver concentrations without pathologic changes in laboratory parameters and without histological changes of organs.”