Patent EA-000291-B1 (EA)
Title: Modular prosthesis
Inventor: JOHNSON WESLY D
IPC: H04W8/24
Filed: 1996-12-05
Abstract: 1. A kit for making a modular prosthesis comprising a first member having walls defining a cavity and a clamp releasably clampable within said cavity, the clamp having a first, rest configuration having a predetermined dimension in a first direction, instrumentation for clamping external stimulus in second direction, perpendicular to said one direction to reduce said dimension in one direction sufficient to permit said clamp to be at least partially received in said cavity, said predetermined dimension being such that upon withdrawal of the external stimulus, the clamp returns toward its rest configuration with consequent increase in its dimension in the first direction sufficient to strongly clamp to said member. 2. The kit of Claim 1 wherein said cavity has a surface that is congruent to a surface of the clamp that is received in the cavity to provide surface-to-surface of the clamp to the cavity. 3. The kit of Claim 1 or 2 wherein the clamp comprises a metal rod having an axial dimension and a transverse dimension that is increased upon decrease in said axial dimension, and wherein said cavity is shaped to axially receive the rod. 4. The kit of Claim 3 wherein said metal rod includes an axial bore that is closed at one end. 5. The kit of Claim 4 including instrumentation for clamping external stimulus the instrumentation including means insertable in said bore for bearing against said closed bore end to elongate the rod sufficiently to enable it to be received in the cavity. 6. The kit of any preceding Claim wherein said prosthesis includes a second member configured to snugly receive at least a portion of the first member in any of several orientations, and wherein said cavity walls are configured to expand into clamping contact with said second member as said clamp moves from its second shape toward its first shape to fixedly support the second member in a predetermined orientation with respect to the first member. 7. The kit of Claim 1 wherein said clamp is of shape memory alloy having superelastic properties at body temperature. 8. The kit of Claim 3 wherein said clamp comprises a rod having end portions and wherein said instrument comprises a handle including a manual squeezing element, means for releasably gripping the rod adjacent one of its end portions and means responsive to squeezing of the handle to impart axial tensile force to the other end portion of the rod to stretch the rod. 9. The kit of Claim 8 wherein said rod has an axial bore open at one end and a fastener adjacent said open end, and wherein said releasable gripping means includes means for fastening to said fastener. 10. The kit of Claim 9 wherein said instrument includes a shaft receivable through the open end of the bore and engaging the rod adjacent its other end portion for imparting tensile axial force to the rod. 11. The kit of any preceding Claim wherein said first member comprises an elongated stem receivable in the marrow cavity of a long bone, the stem having an axial bore forming said cavity. 12. The kit of any preceding Claim wherein confronting walls of the clamp and cavity are so configured as to urge the clamp toward one direction rather than the opposite direction with respect to the cavity upon any repeated slippage between said confronting walls. 13. The kit of Claim 12 wherein the clamp and cavity have confronting walls that are tapered outwardly from a first position to a second position along the cavity so that any slippage between confronting surfaces of the clamp and cavity tends to draw said clamp toward said second position. 14. The kit of any Claims 1-11 wherein confronting walls of the clamp and cavity are so configured as to resist movement between the clamp and the cavity due to repeated slippage between said confronting walls. 15. The kit of Claim 1 wherein said clamp is hollow and has an outer surface engaging said cavity and an inner surface. 16. The kit of Claim 25 wherein said hollow clamp has walls, an open end and a closed end, and having an outwardly extending skirt at its open end, the cavity of said first member having a rim sized to encounter and bear against said skirt when the second member portion is forced into the cavity, whereby walls of the clamp between the first and second members are elongated, and Wedge and seal said members together when force forcing the second member portion into the cavity is removed. 17. Method for assembling a modular prosthesis, comprising providing a first prosthesis member having walls defining a cavity, providing a clamp having a first, rest configuration having a predetermined dimension in a first direction, subjecting the clamp to an external stimulus in the second direction perpendicular to first direction to reduce the dimension in said first direction with concurrent expansion of a clamp dimension in a second direction, inserting the clamp in said cavity, and withdrawing said external stimulus to allow the clamp to return toward its first, rest configuration with consequent increase in its dimension in the first direction sufficient to strongly clamp to said first prosthesis member. 18. Method of Claim 17, including, before withdrawal of said stimulus, the step of receiving at least a portion of the first member in a second prosthesis member, adjusting the relative orientation between the first and second members, and withdrawing said stimulus to enable said clamp to return toward its first, rest configuration, the cavity walls of the first member being configured to expand into clamping contact with said second member as said clamp moves from its second shape toward its first shape to fixedly support the second member in a predetermined orientation with respect to the first member. 19. Method of Claim 17 including the step of orienting a second prosthesis member within a cavity in said clamp with a wall of the clamp separating said members, whereupon said clamp, upon withdrawal of said external stimulus with consequent increase of its wall thickness dimension in said first direction, clamps said members together. 20. Method of Claim 17, using the kit as claimed in any of Claims 1-16.