U.S. patent number 3,681,786 [Application Number 05/054,443] was granted by the patent office on 1972-08-08 for solid human prosthesis of varying consistency.
This patent grant is currently assigned to Medical Engineering Corporation. Invention is credited to Henry W. Lynch.
United States Patent |
3,681,786 |
Lynch |
August 8, 1972 |
SOLID HUMAN PROSTHESIS OF VARYING CONSISTENCY
Abstract
A surgically implantable prosthesis formed from a single piece
of inherently flexible elastomeric, physiologically inert material
and a polyester felt pad embedded within the prosthesis and having
an exposed surface to provide for ingrowth of body tissue. The one
piece prosthesis is radiated to provide areas of different
flexibility in accordance with the function to be performed by the
prosthesis.
Inventors: |
Lynch; Henry W. (Racine,
WI) |
Assignee: |
Medical Engineering Corporation
(Racine, WI)
|
Family
ID: |
21991097 |
Appl.
No.: |
05/054,443 |
Filed: |
July 13, 1970 |
Current U.S.
Class: |
623/23.41;
128/DIG.21; 623/21.15 |
Current CPC
Class: |
A61F
2/18 (20130101); A61F 2/4241 (20130101); A61F
2002/183 (20130101); A61F 2002/30563 (20130101); A61F
2002/3082 (20130101); A61F 2250/0029 (20130101); Y10S
128/21 (20130101); A61F 2002/30014 (20130101); A61F
2002/4243 (20130101) |
Current International
Class: |
A61F
2/18 (20060101); A61F 2/42 (20060101); A61F
2/00 (20060101); A61F 2/30 (20060101); A61f
001/18 (); A61f 001/22 () |
Field of
Search: |
;3/1,6
;128/92R,92C,92CA,DIG.21 ;264/22 ;204/158R,158HE |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Frinks; Ronald L.
Claims
I claim:
1. A surgically implantable prosthesis comprising:
a one-piece body of inherently flexible elastomeric,
physiologically inert material, said body having an enlarged center
portion and an outwardly projecting connecting portion, an enlarged
edge around the outer periphery of said connecting portion,
said center portion and said outwardly projecting portion having a
greater density than said outer edge,
and a number of polyester felt pads in said enlarged edge, each pad
having an exposed section on the surface of said edge for promoting
ingrowth of tissue.
2. A surgically implantable joint comprising:
a single piece of inherently flexible elastomeric, physiologically
inert material having an enlarged center portion, an outwardly
projecting portion on each side of said center portion and a
felt-like pad embedded in said outwardly projecting portion, said
pad being wider than said outwardly extending portion whereby the
edge of said pad is exposed along each edge of said outwardly
extending portion to promote tissue ingrowth.
3. The joint according to claim 2 wherein said outwardly projecting
portions have a greater rigidity than said center portion.
Description
BACKGROUND OF THE INVENTION
The use of silicone rubber in a device designed for replacement of
a damaged or diseased part of the body is well known. Various types
of prosthetic devices have been made to replace the joints and
various bone and cartilage structures in the body. A typical
example of such a device is shown in the Swanson U.S. Pat. No.
3,462,765, entitled "Surgically Implantable Prosthetic Joint" which
has an enlarged center portion that forms the joint and two stem
portions that are inserted into the intramedullary canals of the
adjacent bones. Difficulties have been encountered in using this
device since it has substantially an identical degree of
flexibility throughout its length and tends to bend in the smaller
portions rather than in the joint. The stem portions, due to the
nature of the silicone rubber, are not susceptible to tissue
ingrowth and tend to become loose in the intramedullary canals of
the bones.
SUMMARY OF THE INVENTION
The surgically implantable prosthesis of this invention provides a
one piece device having different degrees of flexibility in order
to more readily duplicate the body function for which it is
intended. This is accomplished by subjecting the inherently
flexible member to different degrees of radiation allowing for
greater flexibility at the joints and greater rigidity in the other
portions of the prosthesis. Tissue ingrowth is also promoted by
embedding a polyester felt pad in the device leaving exposed
sections of the felt pad on the surface of the device for
attachment by tissue ingrowth.
Other objects and advantages of this invention will be apparent
from the following detailed description when read in conjunction
with the accompanying drawings.
DRAWINGS
FIG. 1 is a perspective view of an implantable prosthesis according
to the invention in the form of a finger joint;
FIG. 2 is a sectional view taken on line 2--2 of FIG. 1 of the
prosthesis shown in FIG. 1;
FIG. 3 is an enlarged view of one of the stems showing the felt pad
in one of the stem portions;
FIG. 4 is a view partly in cross-section showing the prosthesis of
FIG. 1 in position within the adjacent bones of a finger;
FIG. 5 is a view of a one piece surgically implantable cartilage
for an ear;
FIG. 6 is a cross-section taken on line 5--5 of FIG. 4 showing the
varying degrees of flexibility of the cartilage for the ear.
DESCRIPTION OF THE INVENTION
The invention as disclosed herein is described for use as a finger
joint or the cartilage for an ear. Obviously, a device can be
shaped to replace any other bone or cartilage structure where
different degrees of flexibility are required to more accurately
duplicate the function of the part of the body which has been
replaced. In FIGS. 1 through 3, a finger joint is shown having
substantially the same shape as shown in the Swanson U.S. Pat. No.
3,462,765. This joint includes a body 10 molded of inherently
flexible elastomeric, physiologically inert material such as
silicone rubber. The body has an enlarged center portion 12 with a
pair of oppositely projecting stem portions 14 and 16. The stem
portions are tapered for insertion into the intramedullary canals
18 of the adjacent bone ends 20 of the finger. The center portion
12 which is wider than it is thick is provided with a groove or
slot 22 to reduce the thickness of the joint to allow the joint to
flex.
In accordance with the invention, the center portion 12 is provided
with a greater degree of flexibility than the stem portions 14 and
16 by subjecting the center portion 12 to a lesser amount of
radiation than the stem portions. As an example, the center portion
12 is radiated for a maximum of 2 minutes, while the stem portions
are radiated for at least 4 minutes. This is accomplished by
masking the center portion 12 for the first 2 minutes and then
removing the mask and radiating the entire device for 2 minutes
more.
Tissue ingrowth is promoted by means of polyester felt pads 26
which are embedded within the stem portions 14 and 16. These pads
26 (as seen in FIG. 3) are formed from Dacron felt and are slotted
(as shown in dotted line) prior to molding of the joint. The pad is
laid across the mold at the parting line, and after molding, the
edges are trimmed to leave an exposed edge 28 around the parting
line in the stems 14 and 16.
In FIGS. 5 and 6, a complete ear cartilage 40 is shown having a
center portion or base 30, an outwardly projecting connecting
portion 32 and an outer edge 34. The ear cartilage 40 is initially
molded to the approximate shape of the ear to be replaced from a
silicone rubber. The center portion 30 is made substantially harder
than the connecting portion 32 and rim 34 of the ear to provide a
solid base for attachment to the ear. The softness of the outer
edge 34 is retained to give a natural flexibility to the whole
ear.
The density of the center portion 30 is increased by selectively
radiating the center portion 30 to a greater extent than the
connecting portion 32. This can be done by masking the connecting
portion 32 and outer edge 34. The center portion 30 is then
subjected to a predetermined amount of radiation. The middle
connecting portion 32 is then exposed and both the center portion
30 and the connecting portion 32 are exposed to radiation for a
predetermined period of time.
The ear cartilage 40 is initially secured to the body by promoting
tissue ingrowth into a Dacron felt pad 25 located on the center
portion 30. The pad 25 is formed from a plurality of Dacron fibers
randomly arranged into a compact permeable felt-like pad. The pad
is molded into the base allowing the silicone rubber to penetrate
into a small amount of the pad 25. The exposed side of the pad 25
is then free for tissue ingrowth.
After attachment, skin is progressively grafted to the surface of
the cartilage until it is completely covered. The grafted skin is
retained on the cartilage by means of small felt pads 42 provided
in recesses 44 on the outer edge 34 of the cartilage. These pads 42
are also formed of Dacron fiber and are secured in the recesses 44
by molding in place. The pads 42 are molded in place in the
silicone rubber by allowing the silicone rubber to impregnate the
portion of felt lying next to it and anchoring it thereby.
Although the prosthesis disclosed has been described only in
connection with replacement as joints or as an ear, it should be
understood that any other cartilage could be replaced with the
prosthesis of this invention where various degrees of flexibility
are required. For example, the nose can be rebuilt by a single
piece having a hard center and flexible projecting portions to
duplicate the function of the cartilage of the nose .
* * * * *