Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Patent
1990-08-21
1991-10-29
Shay, Randy Citrin
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
623 23, A61F 230
Patent
active
050612883
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
lt has been known for some time how to replace worn, or in other ways damaged, joints--for instance joints damaged by rheumatism, by removing a joint end from a bone and replacing this end with an artificial part. These artificial parts include a joint part and a connection part that is inserted into the cavity of the remaining bone. The fastening of the artificial part in the bone has been carried out in different ways, for instance, the connection part has been threaded and/or cemented into the bone.
Presently available artificial parts have a number of drawbacks. Firstly, this method of fastening is comparatively complicated and time consuming. Secondly, with time, great loads, for instance in the vicinity of knee joints and thigh bones, cause an increasing play between an artificial part and bone, which may require a replacement of the artificial part. Change of the artificial part normally involves the shortening of the bone to obtain adequate material in which to fasten the artificial part. After a few replacements of the artificial part, so little of the bone remains that the joint must be made rigid due to the lack of bone material.
A further drawback of the artificial parts known thus far is that the natural formation of blood vessels cannot occur within inner cavity of the bone, which presumably further reduces the life span of the mounting of the artificial part and, thus, of the artificial part itself.
SUMMARY OF THE INVENTION
Some objects of this invention are to solve the above mentioned problems and to provide a simple, useable, artificial part fastening or mounting that is easy to apply, that does not need to be exchanged, and that allows improved vascularization. Other and further objects and advantages will appear hereinafter.
These objects may be achieved in accordance with the present invention by means of a supporting structure that is inserted into the axial cavity of the bone. This supporting structure is provided with bristles, fibers, loops, or the like, with such length that the combined diameter of the device is somewhat larger than the cavity in the bone, allowing at least some of the bristles, fibers, loops, or the like to retain a certain pretension at mounting. In other words, when the fastening element is inserted into the hollow of the bone, the bristles are bent somewhat, thereby causing greater resistance against withdrawal than against insertion. It will in fact be practically impossible to withdraw the fastening element. Preferably the number of bristles, fibers or the like is very large. In this way extensive contact between bone and the artificial part fastening element is obtained simultaneously as an adaption is automatically made to possible irregularities on the inside of the bone.
Furthermore, by fabricating the bristles, fibers, or loops in titanium, the bone and the artificial part fastening element will grow together and with time will become integrated. Bleeding and vascularization can take place between the bristles, fibers or loops. Furthermore, it is also possible to make the supporting structure more or less porous or open. Since the tensions are less as you go further into the bone, the fastening element can be more open or have fewer bristles, further within the bone. The length of the bristles, and the density thereof, are primarily governed by the forces that have to be transferred. Therefore, the density of the bristles need not necessarily be the same over the entire length of the fastening element.
If bristles of titanium are used, many thin bristles can be used in view of the hard, stiff character of titanium. In the alternative, titanium-containing alloys coated by titanium can be used. It is also possible to use plastic materials coated with titanium.
The bristles may initially be directed radially or possibly somewhat rearward. It is also possible that only some of the bristles are so directed.
The supporting structure need not necessarily be rigid, but may allow a certain elasticity that may preferably be calcul
REFERENCES:
patent: 4681590 (1987-07-01), Tansey
Berggren Anders
Rohman Hakan
Shay Randy Citrin
Unilink Inc.
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