Biphasic Collagen Membrane or Capsule for Guided Tissue Regeneration

Abstract

A biocompatible, resorbable biphasic collagen membrane having a first area of relatively higher tensile strength and stiffness and lower porosity and a second area of relatively lower tensile strength and stiffness and higher porosity, and a method of manufacturing the such a membrane.

1 . A biocompatible, resorbable biphasic collagen membrane comprising a first area of relatively higher tensile strength and stiffness and lower porosity and a second area of relatively lower tensile strength and stiffness and higher porosity. 
     
     
         2 . A membrane as claimed in  claim 1 , wherein said second area is formed by an array of perforations through said membrane. 
     
     
         3 . A membrane as claimed in  claim 1 , wherein said membrane has the configuration of a tubular cartridge with one closed axial end and an oppositely disposed open axial end. 
     
     
         4 . A membrane as claimed in  claim 3 , wherein said closed axial end has a spherically rounded configuration. 
     
     
         5 . A membrane as claimed in  claim 1 , wherein said membrane is formed of collagen fibers having a native fibrous structure and a fiber length of from 0.2 to 3 millimeters. 
     
     
         6 . A membrane as claimed in  claim 5 , wherein said fibers have an average length of about 1.5 millimeters. 
     
     
         7 . A membrane as claimed in  claim 1 , wherein said first areas have a tensile strength of approximately 3600 g/mm 2 , a tensile modulus of approximately 95,000 g/mm 2 , pore diameters of less than 50 microns, and a porosity of less than 20%, and said second areas have a tensile strength of about 35 g/mm 2 , a tensile modulus of approximately 560 g/mm 2 , pore diameters of greater than 50 microns, and a porosity of more than 50%. 
     
     
         8 . A method of making a biocompatible, resorbable biphasic collagen membrane comprising a first area of relatively higher tensile strength and stiffness and lower porosity and a second area of relatively lower tensile strength and stiffness and higher porosity, said method comprising:
 forming a suspension of collagen fibers in an alcohol/water solution;   pouring the suspension into the mold cavity of a mold;   subjecting the mold to freezing temperature until the suspension in the mold solidifies;   opening the mold;   subjecting the frozen suspension to freeze drying to produce a membrane;   spraying the freeze-dried membrane with an alcohol/water solution;   thereafter subjecting the membrane to drying; and   heat treating the dried membrane;   
       wherein perforations are formed in the membrane at some point during the execution of said method. 
     
     
         9 . A method as claimed in  claim 8 , wherein said suspension contains from 10 to 60 mg/ml of collagen fibers having a length of 0.2 to 3 mm in a 5 to 25% solution of alcohol in water. 
     
     
         10 . A method as claimed in  claim 8 , wherein the membrane is sprayed with an alcohol/water solution containing from 40 to 70% alcohol. 
     
     
         11 . A method as claimed in  claim 8 , wherein said perforations are formed in the membrane during casting by extending a plurality of pins through the mold in which the membrane is formed. 
     
     
         12 . A method as claimed in  claim 8 , wherein said perforations are formed by perforating the membrane after the heat treatment. 
     
     
         13 . A method as claimed in  claim 8 , wherein the perforations are formed by selective rehydration by spraying only selected areas of the freeze-dried membrane with the alcohol/water solution. 
     
     
         14 . A method as claimed in  claim 8 , wherein the heat treatment is effected at a temperature of from 100 to 140° C. for a period of from 15 minutes to 2 hours.