Modular hip stem prosthesis apparatus and method
AssigneeVenus Corporation
InventorDavid P. Luman
Life of this patent
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Abstract
A modular hip stem prosthesis including a hip stem with an integral, enlarged shoulder and a neck section mountable to the hip stem. The integral, enlarged shoulder is designed to closely conform to the metaphyseal region to securely mount the hip stem in the end of the femur. The enlarged, shoulder portion of the hip stem is also selectively configured to be fabricated as a separate element so as to allow one of a plurality of distal stems to be mounted to the enlarged shoulder to create the hip stem. The neck section readily adapts the hip stem prosthesis for repair and replacement of the components of the total hip replacement without requiring replacement of the hip stem.
Claims11
A modular hip stem prosthesis comprising:
- a hip stem comprising a distal portion having a first end and a second end, said first end comprising longitudinal flutes along an incremental length of the distal shaft and a coronal slot, said second end having an outwardly extending shoulder, said shoulder comprising a partial, first circular profile concentric with the axis of said distal shaft and extending to a second, partial circular profile offset from said first circular profile, the center of said second circular profile lying in a plane with said coronal slot, said shoulder tapering distally toward said distal shaft in a taper comprising a plurality of terraces oriented orthogonal to said axis of said distal shaft, said hip stem including an axial bore in said second end and extending through said shoulder, said bore including a cylindrical section and an outwardly flaring tapered section, and
- a neck comprising a shaft having a cylindrical section and a tapered section, said shaft being dimensionally configured to be telescopically received in said bore with said shaft cylindrical section being received slidingly in said bore cylindrical section in close fit relationship and said shaft tapered section being received in said bore tapered section in locking relationship.
A modular hip stem prosthesis comprising:
- a distal stem comprising a cylindrical shaft having a plurality of longitudinal flutes along an incremental length of the distal end and a coronal slot;
- a diametrally enlarged shoulder formed at the proximal end of the distal stem, said shoulder having a generally ellipsoidal cross section offset from the axis of said distal stem, said shoulder tapering toward the distal end of said distal stem in a plurality of terraces oriented orthogonal to said distal stem;
- a first coaxial bore in said distal stem at said proximal end, said first coaxial bore having a tapered bore terminating in a cylindrical bore, said cylindrical bore terminating in a threaded bore;
- a neck having a truncated conical section for demountably receiving a ball and an axle adapted to be telescopically received in said first coaxial bore, said axle having a coaxial throughbore and a tapered shaft dimensionally configured to be received in press fit relationship in said tapered bore and a cylindrical shaft dimensionally configured to be telescopically received in said cylindrical section in sliding relationship;
- and
- a bolt for passing through said coaxial throughbore into threaded engagement in said threaded bore.
A method for providing a hip stem prosthesis comprising:
- preparing a hip stem by forming a distal shaft with a cylindrical cross section and a plurality of longitudinal flutes along a portion of the length of said distal shaft, said distal shaft including a coronal slot at said first end, an eccentric, truncated shoulder at a second end of said distal shaft, said shoulder being configured as a cylindrical shape intersecting the axis of the distal shaft to provide an eccentric, truncated profile to said shoulder;
- forming an axial bore in said second end of said distal shaft, said bore having a first, tapered section and a second, cylindrical section;
- and
- obtaining a neck for mounting to said hip stem by preparing a shaft on said neck, said shaft having a distal, cylindrical portion and a tapered portion, said distal, cylindrical portion being telescopically received in mating relationship with said cylindrical section of said bore, said tapered portion of said shaft mating in press-fit relationship in said tapered section of said bore in said hip stem.
Dependencies are inferred from the claim text.