Expandable bone implant

Abstract

An expendable bone implant has a first member with a coronal end portion configured for supporting a prosthesis. A second member is at least partially porous, engages the first member, and is configured to expand outwardly upon a longitudinal force being applied to at least one of the first and second members. This anchors the implant in bone before mastication forces are applied to the implant.

1 . An implant comprising:
 a first member having a coronal end portion configured for supporting a prosthesis; and   a second member, being at least partially porous, engaging the first member, and configured to expand outwardly upon a longitudinal force applied to at least one of the first and second members to anchor the implant in bone before mastication forces are applied to the implant.   
   
   
       2 . The implant of  claim 1  wherein the second member includes porous metal. 
   
   
       3 . The implant of  claim 1  wherein the second member includes tantalum. 
   
   
       4 . The implant of  claim 1  wherein the implant is a dental implant. 
   
   
       5 . The implant of  claim 1  wherein the second member is initially secured to the first member only by a loose press-fit that permits the second member to be separated from the first member by hand. 
   
   
       6 . The implant of  claim 1  wherein the second member is initially separate from the first member for placement in a bore in bone before the first member is assembled to the second member. 
   
   
       7 . The implant of  claim 1  wherein the second member has a cavity, and wherein the first member has an apical end portion configured for insertion into the cavity. 
   
   
       8 . The implant of  claim 7  wherein the cavity defines an inner diameter of the second member, and wherein the apical end portion has an outer diameter that is greater than the inner diameter so that inserting the apical end portion into the cavity expands the second member radially outward. 
   
   
       9 . The implant of  claim 7  wherein the apical end portion is tapered inwardly as it extends apically for being disposed within the cavity. 
   
   
       10 . The implant of  claim 7  wherein the apical end portion comprises threads for engaging the second member. 
   
   
       11 . The implant of  claim 1  wherein the first member has an apical end portion and the second member is generally cup shaped for at least generally covering the apical end portion of the first member. 
   
   
       12 . The implant of  claim 1 , wherein the second member has a generally cylindrical wall with a thickness of about 0.020 inches to about 0.040 inches. 
   
   
       13 . The implant of  claim 1 , wherein the second member has a modulus of elasticity that is less than a modulus of elasticity of the first member. 
   
   
       14 . The implant of  claim 1  wherein the second member has sufficient strength to cut into bone during expansion of the second member. 
   
   
       15 . The implant of  claim 1  wherein the second member has a compressive strength in a range from about 50 MPa to 90 MPa. 
   
   
       16 . The implant of  claim 1  wherein the second member has a stiffness of about 3 Gpa or less. 
   
   
       17 . The implant of  claim 1  wherein the first member comprises a body defining a generally longitudinal cavity and at least one opening on the body providing generally radial access to the longitudinal cavity, and
 wherein the second member is at least partially disposed within the longitudinal cavity and being configured to expand radially into the at least one opening.   
   
   
       18 . The implant of  claim 17  wherein each at least one opening forms a generally longitudinally extending slot so that the second member expands to form a generally longitudinally and radially extending rib through each slot for engaging bone. 
   
   
       19 . The implant of  claim 17  further comprising a plurality of slots uniformly spaced around the body. 
   
   
       20 . The implant of  claim 17  wherein the first member has an apical end surface, and wherein the slot formed by each at least one opening longitudinally extends to the apical end surface. 
   
   
       21 . The implant of  claim 17  wherein the body has a cylindrical wall defining the cavity and the at least one opening, and wherein the wall has a thickness at least in the vicinity of the at least one opening of about 0.010 inches or less. 
   
   
       22 . The implant of  claim 17  wherein the slot formed by each at least one opening generally extends at least a majority of the length of the first member. 
   
   
       23 . The implant of  claim 17  further configured to be placed in a hole with a bottom in bone, and wherein the second member has a sidewall and wherein the first member has a driving end configured for receiving a driving tool so that impacting the driving end with the driving tool compacts the second member between the first member and the bottom of the hole to expand the sidewall generally radially outward. 
   
   
       24 . The implant of  claim 17  further configured to be placed in a hole with a bottom in bone, and wherein the second member has a sidewall and a driving end configured for receiving a driving tool so that impacting the driving end with the driving tool compacts the second member between the driving tool and the bottom of the hole to expand the sidewall generally radially outward. 
   
   
       25 . The implant of  claim 1  wherein the first member has a longitudinal cavity, and wherein the second member has a sidewall tapered inwardly as it extends coronally for locating the second member within the longitudinal cavity. 
   
   
       26 . The implant of  claim 1  further comprising a third apical member adjustably engaging the first member, the second member being clamped between the first and third members so that adjusting the first and third members towards each other longitudinally compresses the second member and expands the second member generally radially outward. 
   
   
       27 . The implant of  claim 26  wherein the first and third members are threaded to each other. 
   
   
       28 . The implant of  claim 1  wherein the second member is generally non-circular and has a longitudinal cavity for receiving the first member, and wherein rotating the first member within the second member causes the second member to expand generally radially outward. 
   
   
       29 . The implant of  claim 28  wherein the first member and second member are elliptical or oval. 
   
   
       30 . A method of anchoring a bone implant in a bore in bone comprising:
 providing a first member with a distal end portion and a second member defining a cavity and being at least partially porous;   inserting the second member into the bore; and   expanding at least a portion of the second member radially outward and toward the bone by driving the distal end portion of the first member into the cavity of the second member.   
   
   
       31 . The method of  claim 30  wherein the cavity defines an inner diameter of the second member, and wherein an outer diameter of the first member is greater than the inner diameter of the second member. 
   
   
       32 . The method of  claim 30  wherein the second member includes tantalum. 
   
   
       33 . The method of  claim 30  wherein the second member is placed in the bore before placing the first member in the cavity of the second member. 
   
   
       34 . The method of  claim 30  wherein the implant is a dental implant. 
   
   
       35 . The method of  claim 30  wherein the second member comprises a cylindrical wall about 0.020 to about 0.040 inches thick. 
   
   
       36 . A method of anchoring a bone implant in a bore in bone comprising:
 providing a bone implant having an inner porous member and an exterior shell member defining a longitudinal cavity and at least one generally radial opening from the cavity;   placing the inner porous member at least partially within the longitudinal cavity of the exterior shell member;   placing the implant in the bore; and   expanding the porous member to extrude through the at least one generally radial opening of the shell member to engage bone.   
   
   
       37 . The method of  claim 36  wherein the at least one opening comprises a plurality of generally longitudinally extending slots so that expanding the porous member forms ribs that extend generally radially outward from the shell member and extend generally longitudinally along the shell member. 
   
   
       38 . The method of  claim 36  wherein the porous member extends apically from the shell member.