Osteosynthesis with nano-silver

Abstract

An antibacterial coating that is composed of silver is disclosed, as well as medical tools and implants comprising such a coating, and a method and an apparatus for the production of such a coating. The medical tools or the dental or orthopaedic implant comprises a metal or metal alloy having a treated surface wherein the treated surface is at least partially converted to an oxide film by plasma electrolytic oxidation using a colloid-dispersed system and wherein the converted surface is partially covered by islands formed by colloid-dispersed silver-particles of the colloid-dispersed system. An Ag—TiO 2 coating shows excellent properties in terms of antibacterial efficacy (even against multi-resistant strains), adhesion and biocompatibility. The life-time of an implant in a human body is increased. The antibacterial coating can be used in the field of traumatology, orthopaedic, osteosynthesis and/or endoprothesis, especially where high infection risk exists.

What is claimed is: 
     
         1 . A method for treating a surface of a medical device, the method comprising:
 providing a colloid-dispersed system;   subjecting a medical device to the colloid-dispersed system such that a surface of the medical device which is to be treated is immersed in the colloid-dispersed system; and   generating an AC voltage difference between i) the medical device as a first electrode and ii) a second electrode positioned in the colloid-dispersed system, in order to convert the immersed surface to an oxide film by plasma electrolytic oxidation wherein the converted surface is partially covered by islands formed by colloid-dispersed particles of the colloid-dispersed system.   
     
     
         2 . The method according to  claim 1 , wherein the maximum of the AC voltage difference is provided in the range of 0.1 V to 4800 V. 
     
     
         3 . The method according to  claim 1 , wherein the AC voltage is provided as an asymmetric AC voltage. 
     
     
         4 . The method according to  claim 3 , wherein a negative component of the AC voltage is provided with an amplitude ranging from −1200 V to −0.1 V and/or a positive component of the AC voltage is provided with an amplitude ranging from 0.1 V to 4800 V. 
     
     
         5 . The method according to  claim 3 , wherein the quotient of the positive amplitude divided by the negative amplitude is adjusted to the absolute value of the quotient ranging from >1 to 4. 
     
     
         6 . The method according to  claim 1 , wherein the AC voltage is provided as a symmetric AC voltage. 
     
     
         7 . The method according to  claim 6 , wherein a negative component of the AC voltage is provided with an amplitude ranging from −2400 V to −0.1 V and/or a positive component of the AC voltage is provided with an amplitude ranging from +0.1 V to +2400 V. 
     
     
         8 . The method according to  claim 1  wherein the colloid-dispersed system is a water-based dispersion. 
     
     
         9 . The method according to  claim 1  wherein at least one electrolyte is provided in the colloid-dispersed system. 
     
     
         10 . The method according to  claim 1  wherein the colloid-dispersed particles are provided by at least one member of a group consisting of Ag-particles, apatite-particles, Cu-particles, Zn-particles and a component which is at least one component of a material of the medical device. 
     
     
         11 . The method according to  claim 1  wherein the colloid-dispersed particles are provided as an additive wherein the additive is at least one material selected from a group consisting of metals, oxides, earth minerals and phosphates. 
     
     
         12 . The method according to  claim 1  wherein the colloid-dispersed particles are provided with a concentration of less than or equal to 100 mg/l. 
     
     
         13 - 22 . (canceled) 
     
     
         23 . A method for treating a surface of a medical device, the method comprising:
 providing a colloid-dispersed system;   subjecting a medical device to the colloid-dispersed system such that a surface of the medical device which is to be treated is immersed in the colloid-dispersed system; and generating an AC voltage difference between i) the medical device as a first electrode and ii) a second electrode positioned in the colloid-dispersed system, in order to convert the immersed surface to an oxide film by plasma electrolytic oxidation wherein the converted surface is partially covered by islands formed by colloid-dispersed particles of the colloid-dispersed system,   wherein the AC voltage is provided as an asymmetric AC voltage and/or as a sinus-shaped AC voltage, and wherein the AC voltage difference is generated by a power supply unit and supplied to the first electrode and/or the second electrode such that a uniform electric field distribution is achieved by providing means for connecting the first electrode having an adapted reduced or an adapted increased cross section with respect to the cross section of the connected medical device.