Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Reexamination Certificate
1999-07-19
2001-02-20
Pedro, Philogene (Department: 3732)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
C623S023260, C623S023270, C623S020360, C623S022400
Reexamination Certificate
active
06190417
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a femoral prosthesis for applying to a human body.
2. Prior Art
Conventionally, artificial hip joints have been composed of a socket inserted into the pelvic bone and a femoral prosthesis which has a stem and a spherical head at the end capable of rotatably engaging the socket.
Generally, the stem, made of a metal such as stainless steel or cobalt-chromium alloy, is inserted into a femoral canal and fixed by using cementing compound between the stem and the canal wall. On the acetabular side, the socket is cemented to a pelvic bone, which receives the spherical head of the stem.
Particularly, the stem is inserted deeply within the elongated canal of the femur, and when the artificial joint is loaded, some difference in Young's modulus between the metal stem and the bone tissue causes different amounts of then deformation, then leading to a sinking of the stem into the bone due to relaxation between the cement compound and the bone or between the metal stem and the bone. This results in losing joint function through looseness between the members or, in the extreme case, separation of the stem form the femoral cavity.
Attempts have been made to prevent the looseness between the cement and bone or the metal stem. For example, the stem material has been made from to titanium or titanium alloy instead of stainless steel or Co—Cr alloy, to approximate the Young's modulus of the stem to that of the bone tissue. This attempt failed to completely resolve the looseness problem.
Another improvement has been attempted, in which the stem is formed such that the outside of the stem approaches to inner dimensions of the, to make the gap between the stem surface and the bone canal as narrow as possible and, then inserting the stem into the bone without use of any cementing compound. It was, however, difficult to configure the stem in a shape to accurately duplicated to the inner canal profile. Practically, sufficient products, except in the case of custom-ordered products, have not been available because of patients having great difference in inner femoral profiles.
Recently, in another attempt, U.S. Pat. No. 4,895,571 describes a interlocking femoral prosthesis utilizing surgical screws which pass through the openings formed through the stem, which fix the stem directly to the femoral cavity without use of the cement material.
The screw comprises a straight portion and a wider threaded portion with a greater length than the straight portion, and, on the other hand, the opening formed within the prosthesis stem is set to have a inner diameter wide enough to pass the threaded portion of the screw therethrough, resulting in loose gaps between the screw and the inner wall of the opening. This method can cause severe mechanical instability problems of relative movement, such as micro-movement, of the stem with regard to the bone.
SUMMARY OF THE INVENTION
Considering the above problems inherent in prior art, an object of the invention is to provide a femoral prosthesis having a stem body for a long lifetime to be implanted within a femur bone, wherein the stem body is capable of being fixed within the femur bone by using a system for relaxing the stress loaded onto the femur bone to make the bone and the stem body bend easily when force is applied to the femoral prosthesis and the femur bone.
In the present invention, the femoral prosthesis having a stem body comprises a pinning hole perpendicular to the axis of the stem body, at a portion of a greater trochanter which is formed through the stem body, and a cylindrical cross pin passing through the pinning hole with ends of the pin projecting out of the stem body.
Particularly, the stem body at either side is implanted into the femur so the pinning hole of the stem body is inserted within the femoral canal and a cross pin is inserted into the pinning hole through openings formed through the bone wall so that the cross pin can fix the stem body to the bone preventing even slight movement between the femoral bone and the stem body.
The femoral prosthesis according to the present invention includes a stem body having a specific configuration at its distal potion in order to achieve attachment of said stem body portion to bone tissue which will have grown inside the femoral canal. particularly, the distal portion of the stem body may be corrugated with a plurality of edges and as many grooves alternatingly and longitudinally aligned outside. This configuration of the stem body can promote the anchoring effect of the stem body due to the bone tissue growth and extension.
The femoral prosthesis in accordance with the present invention can be advantageously utilized not only for a replacement of a upper part of a femur bone, for example for healing a failure of the head of femur, but also for a total hip replacement in conjunction with a hip prosthesis.
REFERENCES:
patent: 3466670 (1969-09-01), Christiansen
patent: 4623349 (1986-11-01), Lord
patent: 4895572 (1990-01-01), Chernoff
patent: 5002578 (1991-03-01), Luman
patent: 5702484 (1997-12-01), Goymann et al.
patent: 41 29 724 (1993-03-01), None
patent: 43 20 086 (1994-12-01), None
patent: 43 36 819 (1995-03-01), None
patent: 0 198 163 (1986-10-01), None
patent: 0 567 349 (1993-10-01), None
patent: 1416534 (1965-09-01), None
patent: 1 416 534 (1966-01-01), None
patent: 63-105759 (1988-05-01), None
patent: 63-105758 (1988-05-01), None
patent: 63-164946 (1988-07-01), None
patent: 63-164947 (1988-07-01), None
patent: 63-212350 (1988-09-01), None
patent: 63-212351 (1988-09-01), None
patent: 63-212352 (1988-09-01), None
patent: 63-272345 (1988-11-01), None
patent: 2-041153 (1990-02-01), None
patent: 11 206794 (1999-08-01), None
Ishida Noriyuki
Itoman Moritoshi
Mabuchi Kiyoshi
Tamabuchi Shingo
Ueno Masaru
Hogan & Hartson LLP.
Kyocera Corporation
Pedro Philogene
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