Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Reexamination Certificate
1999-09-17
2001-11-13
Prebilic, Paul B. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
C623S020200, C623S023540, C623S023500
Reexamination Certificate
active
06315798
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a metal backing for inclusion in the manufacture of a prosthetic component and to a metal component incorporating such a backing. More particularly it relates to a means of securing a synthetic plastic material such as polyethylene to a metal backing.
2. Description of the Prior Art
There are often difficulties in securing a metal backing to the synthetic plastic material of a bearing member, sometimes because of the limited space available.
Metal-backed patella components are well known within the industry. They have been subject to limitations on performance related to the small available space for their construction. Generally the factor affecting performance is the reliable and long term attachment of the plastic bearing elements to the metal backing which is used to provide the fixation surface of the device, either for cemented use or for biological ingrowth type applications. Traditional products have used riveting, snapping or molding techniques to provide for the interconnection of parts, these generally being geometric interference caused by this form of gross metal features on the metal backing, posts, holes, rims, etc.
U.S. Pat. No. 5,108,435 relates to an orthopedic implant having a cast mesh tissue ingrowth surface.
The present invention also has applications with regard to other metal backed components, for example, tibial components, elbow and shoulder components and hip cups.
SUMMARY OF THE INVENTION
According to the present invention a metal backing for inclusion in the manufacture of a prosthetic component which has a synthetic polymeric bearing element comprises a metallic element having a front portion with means for attachment to a bone and a rear portion at least part of which is formed by a grill having exposed front and rear faces and which is intended to be embedded within the bearing member during construction.
Thus, due to the construction of the metallic element, the synthetic plastic bearing material of the bearing element can be molded so that both exposed faces of the grill are covered and the grill is embedded within the synthetic plastics material bearing element.
Preferably the grill is located on a metal support and is provided with spacers on its front face to space said front face away from said support. The grill can be cast integrally into said metal support during manufacture.
In one preferred embodiment the front portion of the metal backing is provided with means for attachment to a bone with cement. In an alternative construction the metal backing can be provided with means for mechanical attachment to a bone. Thus, the front portion can be provided with a biological ingrowth surface to facilitate bone ingrowth.
With this arrangement the front portion of the metal backing can be provided with an intricate metal wire mesh and this mesh can be cast integrally into one side of a metal support on the other side of which said grill is located.
The invention also includes a prosthetic metal backed component including a metal backing set forth above and a synthetic plastics material bearing element having a rear bearing surface and a front portion within which the grill is embedded.
With this arrangement the grill is preferably molded integrally into the bearing element during manufacture. As mentioned above the invention is particularly, although not exclusively, applicable for use with a patella component.
The invention can be performed in various ways but one embodiment showing the application of the invention to a patella component will now be described by way of example and with reference to the accompanying drawings.
These and other objects and advantages of the present invention will become apparent from the following description of the accompanying drawings, which disclose several embodiments of the invention. It is to be understood that the drawings are to be used for the purposes of illustration only and not as a definition of the invention.
REFERENCES:
patent: 4041550 (1977-08-01), Frazier
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patent: 4924583 (1990-05-01), Hummel et al.
patent: 4955911 (1990-09-01), Frey et al.
patent: 4978355 (1990-12-01), Frey et al.
patent: 4997445 (1991-03-01), Hodorek
patent: 5019104 (1991-05-01), Whiteside et al.
patent: 5108435 (1992-04-01), Gustavson et al.
patent: 5181924 (1993-01-01), Gschwend et al.
Ashby Alan M.
Schwartz, Jr. Melvin
Slemon Declan P.
Howmedica International S. de R.L.
Lerner David Littenberg Krumholz & Mentlik LLP
Prebilic Paul B.
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