Modular joint prosthesis

Details Modular joint prosthesis Modular joint prosthesis

1997-07-25

2000-10-24

Yu, Mickey

Prosthesis (i.e., artificial body members), parts thereof, or ai

Implantable prosthesis

Bone

623 18, A61F 236, A61F 230

Patent

active

06136035&

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The invention relates to a modular joint prosthesis comprising a head part including a connection for a ball of the joint; a shaft part connectable to the head part by an insert connection; and means for locking the insert connection.
Joint prostheses are produced in the most various shapes and sizes, particularly as hip joint prostheses, to create good adaptation to the anatomical conditions of a given patient.
By means of a multi-part embodiment with nonpositive connection of the corresponding individual parts in the proximal region, the adaptation can be accomplished optimally. At the same time, positioning of the joint head is possible regardless of the shaft diameter.
From European Patent Disclosure EP-B1 0 243 298, a kit for a shaft prosthesis is known, which has a head part that can be provided with a joint ball, an end part anchored in the bone, and an intermediate part that can be positioned between the two. All the parts have conical bores or complementary pegs, and as a result the prosthesis can be assembled by making conical insert connections. The head part and intermediate part each have an axial through bore.
When the individual parts are put together, the corresponding bores are aligned axially in the direction of the shaft. The individual parts of the prosthesis are put together using a tie rod that transmits a force in the axial direction and that penetrates both the head part and succeeding shaft parts and can be screwed into the threaded bore of the end part. As a result, the head part, or the intermediate part, and the end part are firmly tightened against one another, so that loosening of the individual parts of the prosthesis from the mechanical strain during use need not be feared.
The prosthesis described in EP 0 243 298, however, is not bent and is, therefore, not optimally adapted to the anatomy of the hip joint. Furthermore, in other previously known hip joint prostheses, a universal version, that is, one that can be used for the majority of disease cases to be expected, is unattainable.


SUMMARY OF THE INVENTION

In view of the deficiencies in the prior art, it is the object of the invention to create a modular hip joint prosthesis of the generic type referred to at the outset, which by the embodiment of its individual parts offers the possibility of producing a universal usable prosthesis.
The above and other objects are accomplished according to the invention by the provision of a modular hip joint prosthesis comprising: a head part, including a connection for a ball of the joint; a shaft connectable to the head part in a connection region having a curved contour region, in longitudinal section, corresponding to Shenton's arc, the head part including a distal region and the shaft part including a proximal region that together define an insert connection having peripheral edges separated by a gap in the curved contour region; and means for locking the insert; wherein the head part and the shaft part have respective contours in the connection region, in longitudinal section, which merge with one another without substantially changing direction, regardless of a particular relative alignment of the head and shaft parts, except for the gap in the connection region.
The invention encompasses the recognition that by embodying a hip joint prosthesis in two parts, favorable conditions are present for universal use of it, if the resultant structural form, regardless of the type of assembly, is adapted to the form of a modern standard prosthesis. This has been attained with the provisions of the invention, regardless of the alignment of the shaft end relative to the head part. Care is taken particularly to assure that the insert connection for connecting the shaft parts is located in a region which, when it is adapted to the evacuated marrow space, does not require any recesses or widened portions in order to be received. With the provisions of the invention, a shaft prosthesis can be created which enables it to be designed for an individual patient while still

REFERENCES:
patent: 4704128 (1987-11-01), Frey
patent: 4878917 (1989-11-01), Kranz et al.
patent: 5002578 (1991-03-01), Luman
patent: 5080676 (1992-01-01), May
patent: 5562666 (1996-10-01), Brumfield
patent: 5591233 (1997-01-01), Kelman et al.

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