A coupling for use in an apparatus for connecting a prosthesis to the bone of a stump of an amputated limb is described which permits a bio-compatible carbon sleeve forming a part of the prosthesis connector to float so as to prevent disturbing the skin seal around the carbon sleeve. The coupling includes a flexible member interposed between a socket that is inserted within an intermedullary cavity of the bone and the sleeve. A lock pin is carried by the prosthesis and has a stem portion which is adapted to be coaxially disposed and slideably within the tubular female socket for securing the prosthesis to the stump. The skin around the percutaneous carbon sleeve is able to move as a result of the flexing coupling so as to reduce stresses caused by changes in the stump shape and/or movement between the bone and the flesh portion of the stump

Bright, C. W.

Mooney, V.

Owens, L. J.

Reswick, J. B.

English

NASA Technical Reports Server

United States Patent 
Reswick et al. 
[54] PROSTHESIS COUPLING 
[76] Inventors: Robert A. Frosch, Adminstrator of 
the National Aeronautics and Space 
Administration, with respect to an 
invention of James B. Reswick; Vert 
Mooney, both of Downey, Cali.; 
Charles W. Bright; Lester J. Owens, 
both of Titusville, Ha. 
[21] Appl. NO.: 876,438 
[22] Filed Feb. 9,1978 
[51] Int. Cl? ........................... A61F 1/06; A61F 1/08 
[52] US. Cl. ................................................ 3/2; 3/1.9; 
3/12 
[58] Field of Search ............................. 3/1, 1.9-1.912, 
3/2, 12, 12.1 
1561 References Cited 
U.S. PATENT DOCUMENTS 
3,938,198 2/1976 Kahn et al. ........................... 3A.912 
3,947,897 4/1976 Owens ......................................... 3/2 
OTHER PUBLICATIONS 
"A Permanently Attached Artificial Limb", by C. W. 
4,158,895 
[45] Jun. 26, 1979 
Hall et al., Transactions h e r .  Society Artificial Inter- 
nal Organs, vol. XIII, 1967, pp. 329-331. 
Primary Examiner-Ronald L. Frinks 
Attorney, Agent, or Firm-James 0. Harrell; John R. 
Manning 
A coupling for use in an apparatus for connecting a 
prosthesis to the bone of a stump of an amputated limb 
which permits a bio-compatible carbon sleeve forming a 
part of the prosthesis connector to float so as to prevent 
disturbing the skin seal around the carbon sleeve. The 
coupling includes a flexible member interposed between 
a socket that is inserted within an intermedullary cavity 
of the bone and the sleeve. A lock pin is carried by the 
prosthesis and has a stem portion which is adapted to be 
coaxially disposed and slideably within the tubular fe- 
male socket for securing the prosthesis to the stump. 
The skin around the percutaneous carbon sleeve is able 
to move as a result of the flexing coupling so as to re- 
duce stresses caused by changes in the stump shape 
and/or movement between the bone and the flesh por- 
tion of the stump. 
[571 ABSTRACT 
6 Claims, 3 Drawing Figures 
https://ntrs.nasa.gov/search.jsp?R=19790018601 2020-03-20T19:14:38+00:00Z
U.S. Patent Jun. 26, 1979 4,158,895 
4,158,895 
0 1 
PROSTHESIS COUPLING 
ORIGIN OF THE INVENTION 
The invention described herein was made in perfor- 
mance in work under a NASA Contract and is subject 
to the provisions of Section 305 of National Aeronautics 
and Space Act of 1968, Public Law 85-568 (72 Stat. 435, 
402 USCP. 2457). 
BACKGROUND OF THE INVENTION 
The present invention relates to a coupling device for 
a prosthesis, and more particularly to a flexible coupling 
that: floats relative to the bone of an amputated limb so 
as to minimize disturbing the skin seal around the sleeve 
forming part of the socket. 
Artificial limbs, or prothesis, have been used by am- 
putees for many centuries. At first the prothesis were 
crude, shaped as sticks attached to legs or as hooks 
attached to arms. Recently, they have become more 
sophisticated, incorporating electronic equipment and 
servo motors to produce more natural limb movement. 
With all this development, however, problems still re- 
main in means of attaching the prosthesis. When 
porothesis are worn for a long time, the harness and 
clamps create discomforting pressures. 
Attempts have been made to minimize these prob- 
lems, and one example such an attempt is disclosed in 
U.S. Pat. No. 3,947,897. In that particular device, a 
quick disconnecting lock pin is attached to the prosthe- 
sis and a socket is inserted within the intermedullary 
cavity of the bone for receiving such a pin. Interposed 
between the end of the socket and the skin is a sleeve 
constructed of bio-compatible material which provides 
compatibility between the implanted socket and the skin 
line which, in turn, heals therearound. 
One problem with such a device is that the sleeve is 
fmed relative to the socket and stresses that are pro- 
duced as a result of changes in the stump shape tend to 
cause the skin seal around the carbon sleeve to be dis- 
turbed. 
SUMMARY OF THE INVENTION 
The invention includes a coupling for use in appara- 
tus for connecting a prosthesis to a bone of a stump of an 
amputated limb. The apparatus includes a tubular fe- 
male socket having an open lower end adapted to be 
inserted within the intermedullary cavity of the bone. A 
bio-compatible sleeve provides an interface between the 
female socket and the skin directly below the opening in 
the socket. A lock pin is carried by the prosthesis and 
has a stem portion adapted to be coaxially disposed and 
slideably within the tubular female socket for securing 
the prosthesis to the stump. The coupling is constructed 
of resilient material with one end thereof being attached 
to the socket and the other end thereof being attached 
by any suitable material to the bio-compatible sleeve. In 
one particular embodiment the resilient member has a 
bulbous portion which aids in maintaining the sleeve 
and the socket separated for providing a flexible con- 
nection therebetween. In another embodiment, the flex- 
ible material extends radially outwardly from a lower 
end of the socket and is attached to both the socket and 
the bio-compatible sleeve. A reinforcing mesh pleated 
material may be implanted in the resilient member for 
allowing lateral movement therein. 
Accordingly it is an important object of the present 
invention to provide a coupling device for use in a 
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2 
connector so as to permit movement between a bio- 
compatible sleeve and a socket forming part of a con- 
nector for securing a prosthesis to an amputated limb. 
Another important object of the present invention is 
to provide a simple and relatively inexpensive coupling 
for securing a bio-compatible sleeve forming part of a 
prosthesis connector so as to permit the sleeve to float 
relative to the socket. 
Still another important object of the present inven- 
tion is to provide a resilient coupling for a prosthesis 
which minimizes disturbing the skin seal around a bio- 
compatible carbon sleeve as a result of changes in shape 
of a stump of an amputated limb, or having the skin and 
flesh pulled or pushed relative to the bone. 
These and other objects and advantages of the inven- 
tion will become apparent upon reference to the follow- 
ing specification, attendant claims and drawings. 
BRIEF DESCRIgION OF THE DRAWINGS 
FIG. 1 is a perspective view illustrating an apparatus 
for connecting a prosthesis to a bone of a stump of an 
amputated limb, 
FIG. 2 is an enlarged fragmentary cross-sectional 
view of the connector illustrated in FIG. 1, 
FIG. 3 is an enlarged sectional view of a modified 
form of the invention. 
DESCRIPTION OF A PREFERRED 
EMBODIMENT 
Referring in more detail to FIG. 1 of the drawing, 
there is illustrated a stump 10 of an amputated limb, 
such as the upper arm showing the bone 12 remaining in 
the stump. Marrow carried in the lower end of the 
medullary canal is removed so as to accommodate a 
tubular female socket 16 which is constructed of any 
suitable material such as stainless steel. The socket 16 is 
inserted within the medullary canal into the lower end 
of the bone 12 which has been previously trimmed so 
that the bone 12 abuts against an outwardly extending 
shoulder 18 carried adjacent the lower end of the socket 
16. A sleeve 20 of bio-compatible material is carried 
below the female socket so as to provide a compatible 
interface between the implanted socket 16 and the skin 
line 22 which heals therearound. One suitable material 
that is compatible with the flesh and skin of the body is 
vitreous carbon. 
The tubular female socket 16 is secured to the inner 
surface of the bone 12 by means of any suitable bonding 
material, such as methylmethacrylate. Normally, the 
outer surface of the sleeve is grooved or knurled so as to 
enable the bonding material to produce a good interface 
bond between the bone 12 and the socket 16. In order to 
minimize the stress between the socket 16 and the bone 
12 the upper end of the socket such as at 24, tapers 
inwardly. The purpose of this inwardly tapering surface 
24 adjacent the top of the socket 16 is to minimize stress 
concentration that may be incurred when the prosthesis 
is attached thereto. This inwardly tapering surface 24 
may be curved slightly to form a portion of a three-di- 
mensional ogive to match the curvature of the inner 
surface of the bone under maximum bending. This ogive 
also assists in ease of inserting the socket into the bond- 
ing material within the medullary canal. 
The tubular sleeve 16 has an internal annular groove 
26 provided for receiving balls 28 carried within a lock 
pin 30 for securing a prosthesis generally designated by 
the reference character 32 to the stump 10. There may 
be multiple grooves to eliminate need of socket removal 
4,158,895 
3 
should the primary groove become unsuitable through 
wear or damage. 
The prosthesis may be constructed of any suitable 
conventional material and may be attached to the lock- 
ing pin 30 in any suitable manner such as disclosed in 
greater detail in U.S. Pat. No. 3,947,897. 
Interposed between the lower end of the socket 16 
and the bio-compatible sleeve 20 is a resilient coupling 
member 34. The resilient member 34 has an upper por- 
tion that is attached by any suitable bonding agent to the 
lower end of the socket and to the bottom side of the 
shoulder 18. The lower end 36 of the resilient member 
extends into the tubular opening provided in the sleeve 
20 and is secured to a stainless steel sleeve 48 which, in 
turn, is secured to the inner surface of the sleeve 20 by 
any suitable means, such as a bio-compatible bonding 
agent. Ridges may also be provided in the inner surface 
of the sleeve 40 for aiding in securing the resilient mem- 
ber thereto. 
The resilient member 34 includes a bulbous portion 
38 which separates the lower end of the socket 16 from 
the sleeve 20 while providing a flexible connection 
therebetween. The flexible coupling 34 may be con- 
structed of any suitable material such as bio-compatible 
polyurethane or silicone rubber. In one particular appli- 
cation the flexible member 34 is constructed of RTV 
silicone manufactured by Dow Corning Company and 
is identified as MDX4-4210. 
After the socket has been implanted into the stump, 
the skin grows up around the bio-compatible carbon 
sleeve 20 and provides a skin seal therebetween. It is 
important that this seal not be disturbed, however, it has 
been found in the past that as a result of changes in 
stump shape, stresses occur which often break the seal 
between the skin and the bio-compatible sleeve 20. The 
flexible coupling 34 permits the sleeve to more or less 
float relative to the socket 16 to compensate for changes 
in the shape of the stump. As a result, the chance of the 
skin seal provided between the skin line 22 and the 
bio-compatible sleeve 20 being disturbed is minimized. 
It is to be understood of course, that while the pros- 
thesis is shown coupled to an upper arm, the same cou- 
pling could be used on other limbs such as the lower leg. 
Referring now to FIG. 3 of the drawing, there is 
illustrated a modified form of the invention. Like refer- 
ence numerals are utilized for like and corresponding 
parts similar to that of FIGS. 1 and 2. In the embodi- 
ment illustrated in FIG. 3, a different shape bio-compat- 
ible sleeve 42 is utilized. In this particular embodiment 
the bio-compatible sleeve 42 is concentric to the lower 
end of the socket 16 and has a much larger bore extend- 
ing therethrough. A stainless steel sleeve 44 is secured 
to the lower portion of the inner wall of the sleeve 42 
for adding strength thereto. A resilient member 46 has 
its inner end attached to the socket by means of any 
suitable bonding agent. The resilient member 46 has a 
portion 48 extending radially outwardly from the socket 
and is secured to the inner wall 50 of the bio-compatible 
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that changes and variations may be made without de- 
parting from the spirit or scope of the following claims. 
What is claimed is: 
I. A coupling for use in an apparatus for connecting 
a prosthesis to a bone of a stump of an amputated limb, 
said apparatus including a tubular female socket having 
an open lower end adapted to be inserted within an 
intermedullary cavity of the bone, a sleeve for provid- 
ing an interface between said female socket and the skin 
directly below the opening in said socket, and a lock pin 
carried by said prosthesis having a stem portion adapted 
to be coaxially disposed and slideably within said tubu- 
lar female socket for securing said prosthesis to said 
stump, said coupling comprising: 
(a) a resilient member interposed between said tubu- 
lar female socket and said sleeve; 
(b) means for attaching an inner portion of said resil- 
ient member to a lower end of said socket; 
(c) means for attaching an outer portion of said resil- 
ient member to said sleeve; and 
(d) said resilient member having an intermediate flexi- 
ble portion permitting said sleeve to move relative 
to said socket; 
whereby disturbing of the skin seal between said 
sleeve and said skin is minimized by permitting said 
sleeve to move relative to said socket. 
2. The coupling as set forth in claim 1 wherein said 
a tubular member constructed of resilient material; 
one end of said tubular member being attached to said 
the other end of said tubular member being connected 
3. The couding as set forth in claim 2 wherein said 
resilient member comprises: 
socket; and 
to said sleeve. 
35 intermediate flexgle portions comprises: 
a bulbous portion maintaining said sleeve and said 
socket separated while providing a furable connec- 
tion therebetween. 
4. The coupling as set forth in claim 1 further com- 
a pleated reinforcing element carried in said interme- 
5. The coupling as set forth in claim 1 further com- 
said sleeve being concentrically disposed relative to a 
lower end of said socket; and 
said resilient member extending radially outwardly 
from said lower end of said socket resiliently con- 
necting said sleeve to said socket. 
6. An apparatus for connecting a prosthesis to a bone 
(a) a tubular female socket adapted to be inserted 
within an intermedullary cavity of the bone; 
(b) a bio-compatible sleeve adapted to be carried 
adjacent the skin line of the stump so that the skin 
can heal therearound providing a skin seal; 
(c) a resilient member connected between said bio- 
compatible sleeve and said tubular female socket 
providing a resilient connection therebetween so as 
40 prising: 
diate flexible portion. 
prising: 
45 
50 
of a stump of an amputated limb comprising: 
55 
sleeve 42 by any suitable means. A concent-rkally 60 
pleated reinforcing member 52 can be implanted in the 
radially extended portion 48 so as to allow lateral move- 
ment of the resilient member. 
While a preferred embodiment of the invention has 
been described using specific terms, such description is 65 
for illustrative purposes only, and it is to be understood 
to permit shifting of said bio-compatible sleeve 
relative to said socket; and 
(d) a lock pin carried by said prosthesis having a stem 
portion adapted to be coaxially disposed and slide- 
ably within said tubular female socket for securing 
said prosthesis to said stump. * * * * *  


Prosthesis coupling

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