Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Patent
1990-05-02
1991-04-30
Isabella, David J.
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
623 18, A61F 242
Patent
active
050114972
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a joint prosthesis comprising a joint section between two pins to be secured in the bones between which the joint prosthesis shall be mounted and comprising a web of an elastomer, forming a joint section between the pins, said pins being secured in the web by embedding them into the elastomer.
A finger joint prosthesis of this type is disclosed in U.S. Pat. No. 3,886,600 which describes an elbow-joint wherein two rigid pin-like end elements are connected to the elastomer web to be inserted into the medullary canal of the upper and lower arm bones, respectively.
U.S. Pat. No. 4,352,212 describes an embodiment wherein the joint section comprises two elements slidingly engaging each other, one of said elements forming a joint socket and the other one forming a joint pin which is articularely received by the joint socket. The pins on the two elements of the joint section are received in plastic plugs which shall be driven into the canal in the bones to be interconnected by means of the joint prosthesis.
There are also prior art joint prostheses (see e.g. U.S. Pat. No. 3,875,594) which in their entirety consist of an elastomer and by means of pins which accordingly form an integral part of the joint prosthesis, are secured in the bone canal. Such prostheses can be exposed to wear between pin and bone at existing joint articulation, and as a consequence thereof fine particles of the elastomer may penetrate into the human organism where such particles may cause infections and other trouble in different organs.
The object of this invention is to provide a joint of the kind referred to above, by means of which it is achieved that the joint prosthesis will be constructively simple, durable, and easily articulated, that no wear will arise, that a safe, permanent and harmless connecting to the bones is achieved, and that the joint prosthesis can be easily exchanged.
Said object is achieved according to the invention by the joint prosthesis having obtained the characterizing features of claim 1.
In order to explain the invention in more detail, further advantages achieved by the invention also being mentioned, reference is made to the accompanying drawings in which
FIG. 1 is a side view, partly in vertical cross section, of a finger joint prosthesis according to the invention.
FIG. 2 is a plan view, partly in horizontal cross section, of the finger joint prosthesis in FIG. 1,
FIG. 3 is a cross-sectional view showing the finger joint inserted by an operation between two bones,
FIG. 4 is an end view of the attachment plate of the pin in one embodiment, and
FIG. 5 is a corresponding view of another embodiment, and
FIG. 6 discloses a modified embodiment of the joint section of elastomer in the same manner as FIG. 1.
Referring to FIGS. 1 to 5 the finger joint prosthesis shown therein comprises a joint section 10 of an elastomer which can comprise silicon rubber or polyurethane. This joint section is connected with two pins 11 of a biocompatible material, preferably titanium, which are secured in the joint section by the joint section being injection molded around end flanges 12 on the pins so that these end flanges are completely embedded into the elastomer. In order to obtain a satisfactory connection of the pins the flanges form either slots 13 according to FIG. 4 or apertures 14 according to FIG. 5 so that the elastomer during the injection molding can penetrate through these openings. The joint section forms two plate-shaped rectangular enlargements 15 around the flanges and forms between said flanges a relatively thin web 16 slightly curved.
Each pin 11 is inserted into a tubular screw 17 which should also consist of a biocompatible material and preferably is of the same kind as the pins, i.e. it should consist of titanium. The screw has an end flange 18, and is screwed into the canal in the bone wherein it is to be secured as shown in FIG. 3, until the flange engages the bone. The screw will grow on to the bone, which means that the bone will not deteriorate due to uneven loading and that the
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Branemark Per-Ingvar
Persson Jan-Ove
ATOS Medical AB
Institutet for Tillampad Bioteknologi
Isabella David J.
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