Biologically active implants

Abstract

This invention relates to an implant for treating pathological changes in the spinal column and/or locomotor system. According to one embodiment of the invention, the implant has a surface, a body, and an enamel-like or varnish-like coating that is up to 100 μm thick, comprises a biodegradable polymer such as polylactide which has a mean molecular weight of 100 kDa or less, forms an adhesive bond to the surface of the body such that when the implant is implanted, mechanical friction will not abrade or damage the coating, and is adapted to contact bone when implanted. This coating has an osteoinductive effect, which promotes the healing of fractures. Additional osteoinductive materials such as growth factors may be incorporated in the coating. The invention also relates to a method for producing such an implant using the following steps: preparing a dispersion of a biodegradable polymer in an organic solvent; applying the dispersion on the surface to be coated; and allowing the organic solvent to evaporate.

1 . A method for making an implant, comprising:
 preparing a dispersion of a polymer in an organic solvent;   applying the dispersion on a surface of the implant; and   evaporating the organic solvent.   
   
   
       2 . The method of  claim 1 , wherein the application and evaporation steps occur at a temperature between 0 and 30° C. 
   
   
       3 . The method of  claim 1 , wherein the evaporation step occurs in a gaseous atmosphere substantially saturated with a solvent vapor. 
   
   
       4 . The method of  claim 1 , wherein the application and evaporation steps are repeated at least two times. 
   
   
       5 . The method of  claim 1 , wherein the dispersion is a colloidal solution of the polymer in the organic solvent. 
   
   
       6 . The method of  claim 5 , wherein the colloidal solution is filtered prior to its application. 
   
   
       7 . The method of  claim 6 , wherein the colloidal solution is filtered through a micropore filter with a pore size of 0.45 μm or smaller. 
   
   
       8 . The method of  claim 1 , wherein the organic solvent is ethyl acetate or chloroform. 
   
   
       9 . A method for making an implant, comprising:
 preparing a dispersion of a polymer in an organic solvent;   adding a pharmaceutically active agent to the dispersion;   applying the dispersion on a surface of the implant; and   evaporating the organic solvent in a closed space with a controlled gas atmosphere to regulate an evaporation rate of the organic solvent.   
   
   
       10 . The method of  claim 9 , wherein adding the pharmaceutically active agent includes adding a pharmaceutically active agent chosen from a group consisting of osteoinductive agents, biocidal agents, and anti-infection agents. 
   
   
       11 . The method of  claim 9 , wherein preparing the dispersion of the polymer includes preparing a dispersion of a polymer chosen from a group consisting of poly-alpha-hydroxy acids, polyglycols, polytyrosine carbonates, starch, gelatin, cellulose, and interpolymers containing these compounds. 
   
   
       12 . The method of  claim 9 , wherein preparing a dispersion of a polymer includes preparing a dispersion of a biodegradable polymer. 
   
   
       13 . The method of  claim 9 , wherein the evaporation rate is controlled to provide complete evaporation in a time period between 5 minutes and 30 minutes. 
   
   
       14 . The method of  claim 13 , wherein the evaporation rate is controlled to provide complete evaporation in about 10 minutes. 
   
   
       15 . The method of  claim 9 , wherein applying the dispersion on the surface of the implant includes applying the dispersion on a surface of a fracture fixation device. 
   
   
       16 . The method of  claim 9 , wherein preparing a dispersion of a polymer includes preparing a dispersion of a polymer having a glass transition temperature of 37 degrees C. or higher. 
   
   
       17 . The method of  claim 9 , wherein applying the dispersion on the surface of the implant includes applying the dispersion on a surface of a metal implant. 
   
   
       18 . The method of  claim 9 , wherein applying the dispersion on the surface of the implant includes applying the dispersion on a surface of a biodegradable implant. 
   
   
       19 . The method of  claim 9 , wherein preparing the dispersion of the polymer includes preparing a dispersion of a polymer chosen from a group consisting of poly-alpha-hydroxy acids, polyglycols, polytyrosine carbonates, starch, gelatin, cellulose, and interpolymers containing these compounds. 
   
   
       20 . The method of  claim 9 , wherein adding the pharmaceutically active agent includes adding a pharmaceutically active agent chosen from a group consisting of osteoinductive agents, biocidal agents, and anti-infection agents. 
   
   
       21 . A method for making an implant, comprising:
 preparing a colloidal solution of a polymer in an organic solvent;   adding an osteoinductive active agent to the colloidal solution;   filtering the colloidal solution to refine a colloidal particle size;   applying the colloidal solution on a surface of the implant; and   evaporating the organic solvent in a closed space with a controlled gas atmosphere to regulate an evaporation rate of the organic solvent.   
   
   
       22 . The method of  claim 21 , wherein adding the osteoinductive active agent includes adding a osteoinductive active agent chosen from a group consisting of insulin-like growth factors, transforming growth factors, fibroblast growth factors, epidermal growth factors, bone morphogenic growth factors, and platelet-derived growth factors. 
   
   
       23 . The method of  claim 21 , wherein evaporating the organic solvent includes evaporating the organic solvent at a temperature between 0 degrees and 30 degrees C. 
   
   
       24 . The method of  claim 21 , wherein evaporating the organic solvent includes evaporating the organic solvent at approximately room temperature. 
   
   
       25 . The method of  claim 21 , wherein application of the colloidal solution and evaporation of the organic solvent are performed multiple times to form a multilayered polymer coating. 
   
   
       26 . The method of  claim 21 , wherein evaporating the organic solvent in a closed space with a controlled gas atmosphere includes evaporating the organic solvent in a closed space in an atmosphere with controlled vapor content of the organic solvent.