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AssigneeAstra Tech AB
InventorsAnders Holmen, Lars Rasmusson, Mats Wendel
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The present invention relates to a screw implant (1) for insertion into a bore hole (50) arranged in bone tissue, said implant having a cancellous portion (3), and a cortical portion (2) having an axial length such that, when installed in the bore hole (50), the engagement of said cortical portion (2) with the bone tissue will generally be confined to the cortical bone tissue layer (52). Said cortical portion (2) presents an outer surface which is threaded for accomplishing said engagement, and has an outer design such that, when being screwed into said bore hole under action of a screwing torque, said cortical portion (2) acts so as to increase the compression of the cortical bone tissue only, in essentially radial directions of the implant, resulting in a distinct increase of the screwing torque needed for screwing the implant (1). Said increase is usable as an indication that the implant (1) is in place or nearly in place in the bore hole. The invention also relates to an arrangement comprising an implant and a bore hole, and a method for insertion of an implant into a bore hole.
A screw implant (1) for insertion into a bore hole (50) arranged in bone tissue, said implant having a cancellous portion (3), and a cortical portion (2) having an axial length such that, when installed in the bore hole (50), the engagement of said cortical portion (2) with the bone tissue will generally be confined to the cortical bone tissue layer (52), said cortical portion (2) presenting an outer surface which is threaded for accomplishing said engagement, and having an outer design such that, when being screwed into said bore hole under action of a screwing torque, said cortical portion (2) acts so as to increase the compression of the cortical bone tissue only, in essentially radial directions of the implant, resulting in a distinct increase of the screwing torque needed for screwing the implant (1), which increase is usable as an indication that the implant (1) is in place or nearly in place in the bore hole.
A screw implant (1) for insertion into a bore hole (50) arranged in bone tissue, said implant having a cancellous portion (3) presenting an outer surface, and a cortical portion (2) having an axial length, such that, when installed in the bore hole (50), the engagement of said cortical portion (2) with the bone tissue will generally be confined to the cortical bone tissue layer (52), said cortical portion (2) presenting a conical outer surface being threaded for accomplishing said engagement and which has a conical taper such that said conical outer surface forms a non-zero angle (α) of less than 5° in relation to the outer surface of the cancellous portion (3).
A generally cylindrical screw implant (1) for insertion into a cylindrical bore hole (50) arranged in bone tissue, said implant (1) having a cancellous portion (3) presenting a cylindrical outer surface, and a cortical portion (2), having an axial length such that, when installed in the bore hole (50), the engagement of said cortical portion (2) with the bone tissue will generally be confined to the cortical bone tissue layer (52), said cortical portion (2) presenting a conical outer surface being threaded for accomplishing said engagement and which has a conical taper such that said conical outer surface forms a non-zero angle (a) of less than 5° in relation to the cylindrical outer surface of the cancellous portion (3).
A screw implant (1) for insertion into a bore hole (50) arranged in bone tissue, comprising a cancellous portion (3) having a lower cylindrical cancellous portion (3′) and an upper conical cancellous portion (3″) presenting a conical outer surface, wherein said implant (1) is provided with a cortical portion (2), having an axial length such that, when installed in the bore hole (50), the engagement of said cortical portion (2) with the bone tissue will generally be confined to the cortical bone tissue layer (52), said cortical portion (2) presenting a conical outer surface being threaded for accomplishing said engagement and which has a conical taper such that said conical outer surface forms a non-zero angle (α) of less than 5° in relation to the outer surface of the upper, conical cancellous portion (3″).
A screw implant (1) according to any of the preceding claims, wherein a maximum diameter of the implant (1) is located in the cortical portion (2).
A screw implant (1) according to any of the preceding claims, wherein the cortical portion (2) has the shape of a truncated regular cone.
A screw implant (1) according to any of the preceding claims, wherein said angle (α) is in the range 0.5 to 5°.
A screw implant (1) according to any of the preceding claims, wherein said angle (α) is less than less than 3°.
A screw implant (1) according to any of the preceding claims, wherein said angle (α) is in the range 0.5 to 3°.
A screw implant (1) according to any of the preceding claims, wherein said angle (α) is in the range 1 to 2°.
A screw implant (1) according to any of the preceding claims, wherein the axial length of the cortical portion (2) is equal to 3 mm.
A screw implant (1) according to any of the preceding claims, wherein said cancellous portion (3) is provided with a threaded outer surface that merges with said threaded outer surface of the cortical portion (2), such that both threaded outer surfaces are engagable in a common inner threaded surface of the bore hole.
A screw implant (1) according to any of the preceding claims, wherein the implant (1) is provided with at least a first threading (11).
A screw implant (1) according to any of the preceding claims, wherein the cortical portion (2) is adapted to hold a superstructure (20).
A screw implant (1) according to any of the preceding claims, wherein the implant (1) is a dental implant.
A screw implant (1) according to any of the preceding claims, wherein said axial length of the cortical portion (2) is relatively short in relation to the axial length of said cancellous portion (3).
A screw implant (1) according to any of the preceding claims, wherein said cortical portion (2), when being screwed into said bore hole (50), acts so as to slightly compress cortical bone tissue in essentially radial directions of the cortical portion (2).
A method of installing an implant (1) according to any of the preceding claims in a bone, comprising the following steps:
An arrangement for facilitating the insertion of a screw implant (1) in a bore hole (50) arranged in bone tissue, comprising a screw implant (1), having a cancellous portion (3), and a bore hole (50) having a shape generally corresponding to the outer shape of the implant (1), wherein said implant (1) is provided with a cortical portion (2) having an axial length such that, when installed in the bore hole (50), the engagement of said cortical portion (2) with the bone tissue will generally be confined to the cortical bone tissue layer (52), said cortical portion (2) presenting an outer surface, being threaded for accomplishing said engagement, and having an outer design such that when being screwed into said bore hole (50) under action of a screwing torque, said cortical portion (2) acts so as to increase the compression of cortical bone tissue in essentially radial directions of the implant (1), resulting in a distinct increase of the screwing torque needed for screwing the implant (1), which increase is usable as an indication that the implant (1) is in place or nearly in place in the bore hole (50).
An arrangement for facilitating the insertion of a screw implant (1) in a bore hole (50) arranged in bone tissue, comprising a screw implant (1), having a cancellous portion (3), and a bore hole (50) having a shape generally corresponding to a shape of the implant (1), wherein said implant (1) is provided with a cortical portion (2) having an axial length, such that, when installed in the bore hole (50), the engagement of said cortical portion (2) with the bone tissue will generally be confined to the cortical bone tissue layer (52), said cortical portion (2) presenting a conical outer surface being threaded for accomplishing said engagement and which has a conical taper such that said conical outer surface forms a non-zero angle (α) of less than 5° in relation to the outer surface of the cancellous portion (3).
An arrangement for facilitating the insertion of a screw implant (1) in a bore hole (50) arranged in bone tissue, comprising a screw implant having a cancellous portion (3) presenting a cylindrical outer surface, and a bore hole (50) having a shape generally corresponding to a shape of the implant, wherein said implant (1) is provided with a cortical portion (2), having an axial length such that, when installed in the bore hole (50), the engagement of said cortical portion (2) with the bone tissue will generally be confined to the cortical bone tissue layer (52), said cortical portion (2) presenting a conical outer surface being threaded for accomplishing said engagement and which has a slight conical taper such that said conical outer surface forms an angle (α) of less than 5° in relation to the cylindrical outer surface of the cancellous portion (3).
An arrangement for facilitating the insertion of a screw implant (1) in a bore hole arranged in bone tissue, comprising a screw implant (1) having a lower cylindrical cancellous portion (3′) and an upper conical cancellous portion (3) presenting a conical outer surface and a bore hole (50) having a shape generally corresponding to a shape of the implant, wherein said implant (1) is provided with a cortical portion (2), having an axial length such that, when installed in the bore hole (50), the engagement of said cortical portion (2) with the bone tissue will generally be confined to the cortical bone tissue layer (52), said cortical portion (2) presenting a conical outer surface being threaded for accomplishing said engagement and which has a conical taper such that said conical outer surface forms an non-zero angle (α) of less than 5° in relation to the outer surface of the conical part of the cancellous portion (3).
Dependencies are inferred from the claim text.