US 5,290,311 AGranted

Femoral head shaft prosthesis

OwnerFriedrich Baumanninventor

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Abstract

A femoral head shaft prothesis is disclosed with an oblong shaft portion (2, 3) which can be implanted into a marrow cavity (not shown) of an upper thigh bone and can be attached therein by means of a cement layer. According to the invention raised areas in the form of nub rows (17, 18, 19, 21) with small surfaces by comparison to the size of the circumference of the shaft portion (2, 3) are formed at a small number of appropriate locations on said circumference of said shaft portion to serve as spacers in relation to the inner wall of the marrow cavity. The lower shaft portion (2) is formed to be cylindrical and is intended to be inserted into a cylindrically drilled marrow cavity of the femoral neck stump. In this manner a uniform cement layer thickness with only minimal interruptions is achieved, ensuring primary and long-term stability.

Claims18

Dependent claims

A femoral head shaft prosthesis which includes a longitudinal shaft portion having a length for implantation in a marrow cavity of a femoral neck stump and secured by means of a cement layer surrounding the shaft portion, a femoral head portion integral with said shaft portion projecting laterally in relation to a longitudinal axis of the shaft portion, and said shaft having a generally smooth outer surface with a plurality of discrete raised areas having small surface areas relative to a circumference of said shaft portion raised areas comprising:

a plurality of circumferentially spaced lower spacers connected directly with said outer surface and projecting outwardly from a lower portion of said shaft portion for spacing and centering said shaft portion in a receiving cavity formed in said marrow cavity of the femoral neck stump;
said lower shaft portion and said lower spacers having a total outer diameter generally equal to an inner diameter of said receiving cavity;
an upper shaft portion formed on one side as a straight projection of said lower shaft portion having a medial side which widens conically to define a concave surface in a medial area of said upper shaft portion;
a plurality of upper spacers connecting directly with said outer surface and projecting outwardly from aid concave surface for contact against a corticalis medial in said marrow cavity;
and
said lower spacers providing a uniform gap for uniform cement layer thickness about said lower shaft with only minimal interruptions between said receiving cavity and shaft portion to ensure primary and long-term stability.

3 more elements

A femoral head shaft prosthesis which includes a longitudinal lower shaft portion an intermediate shaft portion and an upper shaft portion for implantation in a marrow cavity of a femoral neck stump and being secured by a cement layer surrounding the shaft portion in said marrow cavity comprising:

a femoral head portion integral with said upper shaft portion projecting laterally in relation to a longitudinal axis of the lower and intermediate shaft portions and shad shaft having a generally smooth outer surface with a plurality of discrete raised areas having small surface areas relative to a circumference of said shaft portion;
said raised areas comprising:
a plurality of lower spacers integral with said outer surfaces and projecting outwardly from said lower shaft portion for spacing and centering said shaft portion in a receiving cavity formed in said marrow cavity of the femoral neck stump, said intermediate shaft portion being free of spacers;
said lower shaft portion and said lower spacers having a total outer diameter generally equal to an inner diameter of said receiving cavity;
said intermediate shaft portion having an outer diameter substantially less than said diameter of said receiving cavity;
and
said lower spacers providing a uniform gap for uniform cement layer thickness with only minimal interruptions between said receiving cavity and shaft portion to ensure primary and long-term stability.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/020,903Filed 22 Feb 1993 · continuation
Priority: DE 410158721 Jan 1990
Granted: 1 Mar 1994
Term ends: Not estimatedThe source records don’t support an estimate.

Classification13 codes

A61F 2/30724
Accessories: spacers for centering an implant in a bone cavity, e.g. in a cement-receiving cavity
A61F 2/30771
Special external or bone-contacting surface, e.g. coating for improving bone ingrowth: applied in original prostheses, e.g. holes or grooves
A61F 2/3662
Femoral heads ; Femoral endoprostheses: femoral shafts
A61F 2/367
Femoral shafts: proximal or metaphyseal parts of shafts