Structure for forming bone

Abstract

Structure for promoting the formation of bone comprising a body essentially comprising pharmaceutical grade calcium sulfate and a calcium phosphate or apatite biomaterial in the form of porous granules having an average grain size by weight of between 250 and 3000 micrometers, said biomaterial granules themselves having a specific surface area of between 10 and 50 m 2 /g, a macroporosity formed of pores with an average diameter (average porous volume) of between 2 micrometers and 100 micrometers. The structure has a ratio by weight of calcium sulfate dihydrate to porous calcium phosphate or apatite granules of between 1:3 and 3:1.

1 . Structure for promoting the formation of bone around an implant advantageously made of titanium, said structure being adapted for being at least partly inserted into a bone or a living bone structure or for being in contact with or in proximity to a bone or a living bone structure, said structure comprising an osteogenic body made from a bone reconstruction material essentially comprising pharmaceutical grade calcium sulfate and a slowly or non-resorbable calcium phosphate or apatite biomaterial in the form of porous granules having an average grain size by weight of between 250 and 3000 μm, said biomaterial granules themselves having a specific surface area of between 10 and 50 m 2 /g, a macroporosity formed of pores with an average diameter (average porous volume) of between 2 μm and 100 μm, said osteogenic body having a substantially flat end with an opening extended by a central cavity with a central axis and adapted for receiving at least one end of an implant, said cavity having at least two successive substantially cylindrical parts, i.e. at least a first substantially cylindrical part with a first diameter adjacent to the opening and a second substantially cylindrical part with a second diameter smaller than said first diameter, said successive substantially cylindrical parts being joined to each other by an intermediate zone forming a ledge or a step extending between a substantially circular part of an edge of a first substantially cylindrical part and a substantially circular part of an edge of the second substantially cylindrical part, said substantially circular parts of said edges of said substantially cylindrical parts being separated from one another by a distance measured perpendicular to the central axis of the cavity of between 0.03 times and 0.25 times the diameter of the first substantially cylindrical part, the ratio by weight of calcium sulfate calculated in dihydrate form to porous calcium phosphate or apatite granules being between 1:3 and 3:1. 
   
   
       2 . Structure according to  claim 1 , wherein the biomaterial comprises fluorohydroxyapatite agglomerates. 
   
   
       3 . Structure according to  claim 1  wherein the biomaterial includes calcium carbonate and hydroxyapatite or carbonated hydroxyapatite, the ratio by weight of calcium carbonate to hydroxyapatite of the biomaterial being between 1.5:100 and 5:100, or advantageously between 2:100 and 3.5:100. 
   
   
       4 . Structure according to  claim 3 , wherein the biomaterial includes an organic phase, the organic phase representing between 1% by weight and 5% by weight of the biomaterial. 
   
   
       5 . Structure according to  claim 1 , wherein the structure has an end part into which the bottom of the cavity extends. 
   
   
       6 . Structure according to  claim 1 , wherein the cavity comprises at least three successive substantially cylindrical parts starting from the opening, i.e. a first substantially cylindrical part adjacent to the opening having a first diameter, a second substantially cylindrical part adjacent to the first substantially cylindrical part and having a diameter smaller than the diameter of the first substantially cylindrical part, and a third substantially cylindrical part having adjacent to the second substantially cylindrical part and having a diameter smaller than the diameter of the second substantially cylindrical part, said first and second successive substantially cylindrical parts being joined to each other by an intermediate zone forming a shelf or a step extending between a substantially circular part of an edge of the first substantially cylindrical part and a substantially circular part of an edge of the second substantially cylindrical part, said substantially circular parts of said edges of said first and second substantially cylindrical parts being separated from one another by a distance measured perpendicular to the central axis of the cavity of between 0.03 times and 0.25 times the diameter of the first substantially cylindrical part, while said second and third successive substantially cylindrical parts being joined to each other by an intermediate zone forming a shelf or a step extending between a substantially circular part of an edge of the second substantially cylindrical part and a substantially circular part of an edge of the third substantially cylindrical part, said substantially circular parts of said edges of said second and third substantially cylindrical parts being separated from one another by a distance measured perpendicular to the central axis of the cavity of between 0.03 times and 0.25 times the diameter of the second substantially cylindrical part. 
   
   
       7 . Structure according to  claim 1 , wherein the cavity comprises at least four successive substantially cylindrical parts starting from the opening, i.e. a first substantially cylindrical part adjacent to the opening having a first diameter, a second substantially cylindrical part adjacent to the first substantially cylindrical part and having a diameter smaller than the diameter of the first substantially cylindrical part, a third substantially cylindrical part having adjacent to the second substantially cylindrical part and having a diameter smaller than the diameter of the second substantially cylindrical part, and a fourth part extending between the bottom of the cavity and the third substantially cylindrical part, the fourth part advantageously being substantially cylindrical and having a diameter smaller than the diameter of the third substantially cylindrical part, said first and second successive substantially cylindrical parts being joined to each other by an intermediate zone forming a shelf or a step extending between a substantially circular part of an edge of the first substantially cylindrical part and a substantially circular part of an edge of the second substantially cylindrical part, said substantially circular parts of said edges of said first and second substantially cylindrical parts being separated from one another by a distance measured perpendicular to the central axis of the cavity of between 0.03 times and 0.25 times the diameter of the first substantially cylindrical part, said second and third successive substantially cylindrical parts being joined to each other by an intermediate zone forming a shelf or a step extending between a substantially circular part of an edge of the second substantially cylindrical part and a substantially circular part of an edge of the third substantially cylindrical part, said substantially circular parts of said edges of said second and third substantially cylindrical parts being separated from one another by a distance measured perpendicular to the central axis of the cavity of between 0.03 times and 0.25 times the diameter of the second substantially cylindrical part, and said third and fourth successive substantially cylindrical parts are joined to each other by an intermediate zone forming a shelf or a step extending between a substantially circular part of an edge of the third substantially cylindrical part and a substantially circular part of an edge of the fourth substantially cylindrical part, said substantially circular parts of said edges of said third and fourth substantially cylindrical parts being separated from one another by a distance measured perpendicular to the central axis of the cavity of between 0.03 times and 0.25 times the diameter of the third substantially cylindrical part. 
   
   
       8 . Structure according to  claim 1 , wherein the bottom of the cavity is substantially rounded. 
   
   
       9 . Structure according  claim 1 , wherein the intermediate zone extending between two successive substantially cylindrical parts of the cavity has a curved, advantageously convex, profile. 
   
   
       10 . Structure according to  claim 1 , wherein the cavity is associated with at least one protuberance substantially parallel to the axis of the cavity, said protuberance extending into the cavity and toward its central axis and serving as a guide means for an end of an implant. 
   
   
       11 . Structure according to  claim 11 , wherein the cavity is associated with two or three protuberances extending into the cavity and serving as guide means for the placement of the end of an implant into the cavity. 
   
   
       12 . Structure according  claim 1 , wherein, characterized in that the thickness of the structure at the level of the part adjacent to the opening is smaller than the thickness of the structure at the level of the bottom of the cavity. 
   
   
       13 . Structure according to  claim 12 , wherein the average thickness of the structure at the level of the opening is greater than 0.2 mm, while the average thickness of the structure at the level of the bottom of the cavity is equal to at least twice, or advantageously at least three times the average thickness of the structure at the level of the opening. 
   
   
       14 . Structure according to  claim 1 , wherein the substantially cylindrical parts have a length that varies between 0.75 times the average length and 1.25 times the average length, the average length of the substantially cylindrical parts being determined by dividing the total length of the cavity by the number of parts. 
   
   
       15 . Structure according to  claim 1 , wherein it the structure has a substantially cylindrical outer surface. 
   
   
       16 . Structure according to  claim 1 , wherein the cavity of the structure is at least partly formed by mechanical machining, particularly by drilling. 
   
   
       17 . Structure according to  claim 1 , wherein the biomaterial granules are dispersed in a calcium sulfate phase in a substantially homogeneous fashion. 
   
   
       18 . Structure according to  claim 1 , wherein it contains water, part of which is chemically bonded to the biomaterial granules, the content of water chemically bonded to the biomaterial being between 0.1% by weight and 1% by weight relative to the weight of the biomaterial granules. 
   
   
       19 . Structure according  claim 1 , wherein the biomaterial granules themselves have an apparent density of between 0.5 and 0.6 g/cm 3 . 
   
   
       20 . Structure according to  claim 1 , wherein the calcium sulfate is essentially in dihydrate form. 
   
   
       21 . Structure according to  claim 1 , the structure having a porosity higher than that of a calcium sulfate matrix containing the same quantity of biomaterial and prepared at atmospheric pressure from an aqueous paste of calcium sulfate hemihydrate and biomaterial granules. 
   
   
       22 . Structure according to  claim 1 , comprising more than 90% by weight, of (a) calcium sulfate in dihydrate form, (b) water and/or saline, and (c) biomaterial granules. 
   
   
       23 . Structure according to  claim 1 , said structure enclosed in a sterile vacuum pack. 
   
   
       24 . Ensemble, for example a kit, comprising at least one structure according to  claim 1 , and an implant, having a body with at least one ledge, said body having a shape adapted to the shape of the cavity of the structure. 
   
   
       25 . Bone reconstruction material essentially comprising pharmaceutical grade calcium sulfate and a slowly or non-resorbable calcium phosphate or apatite biomaterial, said material being as defined in  claim 1 . 
   
   
       26 . Tool for creating a perforation or cavity in a bone structure, said tool comprising:
 a metal insert having a free end having a cutting edge, a point, an angle or an inclination, and   a device adapted for generating a sonic or ultrasonic cavitation of the insert and for moving the insert inside the bone structure,   
     said insert having a channel adapted for supplying a liquid under pressure to the free end having the cutting edge, point, angle or inclination. 
   
   
       27 . Tool according to  claim 26 , comprising a means for sealing the bone in the vicinity of the surface through which the insert is introduced and/or for controlling the pressure of the liquid flowing through the hole being formed.