Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Patent
1994-01-27
1997-08-19
Isabella, David
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
623 18, A61F 230, A61F 228
Patent
active
056583494
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to prosthetic joints and, in particular, to a prosthetic joint system for use when bone replacement is required.
2. Description of the Prior Art
Various prosthetic joints are known which include means for replacing bone which the patient has lost as a result of disease, trauma, or bio-mechanical degeneration caused by, for example, a previous joint implant.
FIG. 1 shows a two piece prosthesis 14 of this type which includes a stem 16 and a bone replacement portion 18 which can be a bone graft or a shaped part composed of a plastic material, such as ultra high molecular weight polyethylene (UHMWPE). See "Link Endo-Model Total Femur Replacement", Link America, Inc., East Hanover, N.J., 1989, and "The Leinbach Horizontal Platform Femoral Component", Allo Pro Corporation, St. Petersburg, Fla., 1982.
FIG. 2 shows another prior art construction of this type which comprises a one piece metal prosthesis 10 which includes a proximal portion 12 which serves as a replacement for bone. Examples of prostheses of this general type include those sold by Howmedica under the product designations "Universal 32 mm Proximal Femur Total Hip Components with Polished Loops", "Muller Type 32 mm Proximal Femur", "Harris Calcar Replacement 32 mm Total Hip System", and "Averett Modified Head Neck 32 mm Total Hip System", and those sold by DePuy under the product designation "1031-30/44 Femoral Upper Third".
Although these prostheses have benefited many patients, problems have remained with their use. In particular, with reference to the prostheses of the type shown in FIG. 2, custom prostheses are often needed and even when customized, these prostheses may not fit the patient particularly well, especially in connection with achieving a tight fit between the prosthesis and the patient's bone. These prostheses provide the surgeon with only one choice of replacement at the time of surgery which limits the ability of the surgeon to respond to specific needs or problems ascertained after the surgery has begun. Also, custom prostheses take a substantial amount of time to fabricate and are expensive.
With reference to the prostheses of the type shown in FIG. 1, these can provide the surgeon with some degree of choice at the time of surgery. Typically, a family of stems and a corresponding family of replacement portions 18 are provided to the surgeon. Also, in some cases, parts of the replacement portion can be cut away at the time of surgery to accommodate different amounts of bone loss. See the Allo Pro system, supra. However, these prostheses still suffer from problems in achieving an optimum interface between the stem 16 and the patient's bone. In particular, because of the mechanical configuration of the prosthesis, porous coating of the stem to achieve long term fixation through bone ingrowth is inadvisable since it may reduce the endurance strength or the stem.
Femoral prostheses which include sleeves for engagement with bone are also known in the art. See, for example, Noiles U.S. Pat. No. 4,846,839 and Noiles U.S. Pat. No. 4,790,852. Such prostheses have not included separate bone replacement elements of the type shown in FIG. 1 but in some cases have included an integral bone replacement portion of the type shown in FIG. 2.
SUMMARY OF THE INVENTION
In view of the foregoing state of the art, it is an object of the invention to provide improved joint replacement prostheses having bone replacement means. In particular, it is an object of the invention to provide a modular system whereby the surgeon can select the set of components most suitable to the patient's condition as determined at the time of surgery.
It is a further object of the invention to provide prostheses of the foregoing type having an improved interface between the prosthesis and the patient's bone. In particular, it is an object of the invention to provide a prosthesis employing a sleeve for engagement with the bone and a stem which interlocks with the sleeve. In this way, the sleeve can
REFERENCES:
patent: 4718916 (1988-01-01), Morscher
patent: 4728335 (1988-03-01), Jurgutis
patent: 4790852 (1988-12-01), Noiles
patent: 4846839 (1989-07-01), Noiles
patent: 4908032 (1990-03-01), Keller
patent: 4944759 (1990-07-01), Mallory et al.
patent: 4997448 (1991-03-01), Filer
patent: 5002578 (1991-03-01), Luman
patent: 5026399 (1991-06-01), Englebrecht et al.
"Link Endo-Model Total Femur Replacement," Link America, Inc., East Hanover, New Jersey, 1989.
"The Leinbach Horizontal Platform Femoral Component", Allo Pro Corporation, St. Petersburg, Florida, 1982.
Bobyn John Dennis
Brooks Caleb Emerson
DeCarlo, Jr. Alfred F.
Krygier Jan Janusz
Isabella David
Joint Medical Products Corporation
Klee Maurice M.
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