A prosthetic device has been developed for below-the-elbow amputees. The device consists of a cuff, a stem, a housing, two hook-like fingers, an elastic band for holding the fingers together, and a brace. The fingers are pivotally mounted on a housing that is secured to the amputee's upper arm with the brace. The stem, which also contains a cam, is rotationally mounted within the housing and is secured to the cuff, which fits over the amputee's stump. By rotating the cammed stem between the fingers with the lower arm, the amputee can open and close the fingers

Belcher, Jewell G., Jr.

Carden, James R.

Norton, William E.

West, Thomas W.

English

NASA Technical Reports Server

United States Patent E191 
Norton et al. 
[11] Patent Number: 5,021,065 
[45] Date of Patent: Jun. 4, 1991 
[54] ROTATIONALLY AcmTATED PROSTHETIC 
[75] Inventors: William E. Norton; Jewell G. Belcher, 
HELPING HAND 
Jr.; James R. Carden; Thomas W. 
West, all of Huntsville, Ala. 
[73] Assignee: The United States of America as 
represented by the Administrator, 
National Aeronautics and Space 
Administration, Washington, D.C. 
[21] Appl. NO.: 508,154 
1221 Filed: Apr. 12,1990 
[51] Int. Cl.5 ........................... A61F 2/58; A61F 2/68 
[52] U.S. Cl. ......................................... 623/63, 623/62 
[58] Field of Search .................................... 623/61-65, 
623/57 
[561 References Cited 
U.S. PATENT DOCUMENTS 
2,268,951 1/1942 McElroy ............................... 623/61 
2,347,909 5/1944 jarrett ............................... 623/63 X 
2,349,411 5/1944 Dorrance .......................... 623/63 X 
2,382,404 8/1945 Eberle ................................... 623/63 
2,408,880 10/1946 Reben ................................... 623/63 
Primary Examiner-Ronald Frinks 
Attorney, Agent, or Firm-Jerry L. Seemann; Robert L. 
Broad, Jr. 
1571 ABSTRACT 
A prosthetic device for below-the-elbow amputees hav- 
ing a cuff, a stem, a housing, two hook-like fingers, an 
elastic band for holding the fingers together, and a 
brace. The fingers are pivotally mounted on a housing 
that is secured to the amputee’s upper arm with the 
brace. The stem, which also contains a cam, is rotation- 
ally mounted within the housing and is secured to the 
cuff, which fits over the amputee’s stump. By rotating 
the cammed stem between the fingers with the lower 
arm, the amputee can open and close the fingers. 
13 Claims, 5 Drawing Sheets 
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ROTATIONALLY ACWATED PROSTHETIC 
HELPING HAND 
ORIGIN OF THE INVENTION The invention 
described in this patent application was made in the 
performance of work under a NASA contract and is 
subject to the provisions of Public Law 96-517 (94 Stat 
3019; 35 U.S.C. 200-21 1). 
BACKGROUND O F  THE INVENTION 
Field of the Invention 
This invention relates to a prosthetic device. Specifi- 
cally, the present invention pertains to a prosthetic 
helping hand for use by below-theelbow amputees. 
This prosthetic hand contains a clamping mechanism 
that is opened and closed by rotation of the lower arm. 
Background Information 
Prosthetic devices used to assist people who have 
received a below-the-elbow arm amputation generally 
fall into to two categories: bionic devices and body- 
powered devices. The body-powered devices seem to 
be the most preferred alternative. Many of the current 
artificial limbs have disadvantages which consist of 
being (1) uncomfortable, (2) not very durable, (3) 
heavy, (4) bulky, or ( 5 )  awkward to use. These prob- 
lems are exacerbated for those persons who are very 
active. The present invention overcomes these disad- 
vantages by providing a simple, easy-to-operate pros- 
thetic helping hand with improved comfort and durabil- 
ity. 
SUMMARY O F  THE INVENTION 
The present invention has the ability to assist below- 
the-elbow amputees in performing a variety of tasks. 
This prosthetic hand comprises a clamping mechanism 
that is attached to the stump and is operated by rotation 
of the lower arm. The clamping mechanism is used to 
assist in those functions that would otherwise be per- 
formed by the hand. 
An object of this invention is to provide a prosthetic 
device for a person whose arm has been amputated 
below the elbow. 
Another object of this invention is to provide a pros- 
thetic hand with a clamping mechanism which can 
simulate the work of the thumb against the fingers. 
Still another object of this invention is to provide a 
prosthetic hand which can be operated by the rotational 
movement of the lower arm. 
BRIEF DESCRIPTION OF THE DRAWINGS 
Further details of the present invention are explained 
below with the help of the attached drawings in which: 
FIGS. 1A and 1B represent an end view and a side 
view, respectively, of the cuff and stem assembly be- 
longing to this invention. 
FIGS. 2A, 2B and 2C represent a side view, right end 
view, and left end view, respectively, of the housing 
belonging to this invention. FIGS. 2D and 2E are sec- 
tional views of the housing. 
FIGS. 3A, 3B and 3C represent a top view, side view 
and partial sectional view, respectively, of the fingers 
belonging to this invention. 
FIG. 4 represents an enlarged view of the cuff, stem, 
housing, and fingers in assembled form with the housing 
shown in section. 
FIGS. SA and SB represent perspective views of the 
invention in fully assembled form. FIG. SA shows the 
2 
invention with closed fingers and FIG. 5B shows the 
invention with open fingers. 
DESCRIPTION OF THE PREFERRED 
EMBODIMENT 
A preferred embodiment of the present invention 
comprises a cuff, a stem, a housing, a first finger, a 
second finger, a means for biasing the fingers towards 
each other, and a brace. 
FIGS, 1A and 1B show a cuff 10 having an open end 
11 and a closed end 12. The cuff 10 fits over the stump 
of an amputee’s arm and is usually custom made to 
provide an individual fit. A stem 13 having a plain end 
14 and a cam end 15 is attached to the closed end 12 of 
15 the cuff 10. In the embodiment shown, the stem 13 is 
attached to the cuff 10 by a cylindrical anchor 16 which 
is affixed to the cuff 10. The cylindrical anchor 16 may 
be cast directly into the cuff 10 during fabrication of the 
cuff 10. The plain end 14 of the stem 13 is secured 
20 within the anchor 16 by a pin 17. Thus, the cuff 10 and 
stem 13 are able to act together as a single unit. Alterna- 
tively, the stem 13 may be secured within the cylindri- 
cal anchor 16 by a set screw 19 which is threaded 
through the anchor 16 and against the plain end 14 of 
25 the stem 13. This latter arternative has the advantage of 
allowing the position of the cam end 15 to be adjusted 
relative to the cuff 10. The cylindrical anchor further 
has an outer surface 18 which may serve as a bearing 
race. 
FIGS. 2A, 2B, 2C, 2D and 2E show a housing 20 
having two opposite sides 21, 22. The two opposite 
sides 21,22 have threaded holes 23 for securing a brace 
51 (see FIG. SA) to the housing 20. The opposite sides 
21,22 containing the threaded holes 23 do not have to 
35 be located as shown. The desired orientation of the 
housing 20 relative to the brace 51 will determine the 
location of the opposite sides 21, 22 and the threaded 
holes 23. The housing 20 also has locations 24 for pivot- 
ally mounting a finger 30 (see FIGS. 3A, 3B and 3C) to 
40 the housing 20. In the embodiment shown, the housing 
20 has an inner surface 25 which aligns with the outer 
surface 18 of the cylindrical anchor 16. The inner sur- 
face 25 of the housing 20 may also serve as a bearing 
race. Thus, roller bearings 26 (see FIG. 2E) may be used 
45 between the outer surface 18 of the cylindrical anchor 
16 and the inner surface 25 of the housing 20. The roller 
bearings 26 facilitate rotation of the stem 13 within the 
housing 20. 
FIGS. 3A, 3B and 3C show a finger 30 having a 
50 bearing surface 31 and a clamping end 32. The clamping 
end 32 may have a roughened surface 33 to provide 
better gripping capability to the finger 30. A location 34 
is provided so that the finger 30 may be pivotally 
mounted. 
FIG. 4 shows the housing 20 pivotally mounted on 
the cuff 10 and stem 13 assembly and shows the two 
fingers 30 pivotally mounted to the housing 20. In the 
embodiment shown, the bearing surfaces 31 of the fm- 
gers 30 are held against the cam end 15 of the stem 13 by 
60 an elastic band 41 which is wrapped around the fingers 
30. An alternative to the elastic band 41 would be a 
spring mechanism (not shown) mounted between the 
fingers 30 that would hold the fingers 30 against the 
cam end 15 of the stem 13. 
FIGS. SA and 5B show the invention in its fully 
assembled form. As shown in the figures, a brace 51 is 
attached to the opposite sides 21, 22 of the housing 20. 
The brace 51 consists of a first bar 52 and a second bar 
5 
10 
30 
55 
65 
5,021,065 
3 4 
53. Each of the two bars 52, 53 have two ends 54, 55 a set screw within said threaded hole of said cylindri- 
with a pivot 56 between the two ends 54,55. The pivots cal anchor whereby said set screw locks said stem 
56 are aligned with each other so that they coincide to said cylindrical anchor. 
with the location of the wearer's elbow. Attached to the 4. A prosthetic hand as recited in claim 1, further 
ends 55 of the bars 52, 53 is an adjustable wraparound 5 comprising roller bearings located between said Stern 
57. The adjustable wraparound 57 may contain a nylon and said housing to facilitate rotation Of said Stem 
fabric 58 which can be fastened to itself (e.g., VEL- within said housing. 
CRO) for securing the wraparound 57 to the upper arm. 5. A prosthetic hand as recited in claim 2, further 
Ends 54 of the brace 51 are secured to the housing 20, comprising roller bearings located between said cylin- 
preferably with screws. 10 drical anchor and said housing to facilitate rotation of 
The present invention is utilized by placing an arm said Stem within said housing. 
has ken amputated below the elbow into the 
cuff. '& adjustable wraparound is then secured to the 
6. A prosthetic hand as recited in Claim 3, further 
comprising roller bearings located between said CYrin- 
upper ne housing is thus heid stationary with 
respect to the upper arm by the brace which C O M ~ C ~ ~  Is said stem within said housing- 
the to the housing. When the lower - is 
to the housing. Since the elastic band holds the fingers 
against the cam end of the stem, the cam end moves the 
fingers either apart or together as the stem is rotated 
with the lower arm. Thus, this invention provides a 
below-the-elbow amputee with a clamping mechanism 
which can be used to perform a number of tasks. By 
varying the orientation of the housing relative to the 25 
brace and the stem relative to the cuff, the amputee can 
control the orientation of the fingers as well as the 
opened and closed positions of the fingers. 
drical anchor and said housing to facilitate rotation of 
7. A prosthetic hand as recited in claim 1, wherein 
rotated, the cuff and stem assembly rotate with respect said ends Of said fingers have a roughened 
surface* 
8. A prosthetic hand as recited in claim 1, wherein 
20 said means for holding said bearing surfaces of said 
fingers against said cam end of said stem, comprises an 
elastic band wrapped around said fingers. 
9. A prosthetic hand as recited in claim 1, wherein 
said brace, comprises: 
a first bar having two-ends and also having a pivot 
between said two ends, one of said two ends is 
attached to one of said opposite sides of said hous- 
a second bar having two ends and also having a pivot 
between said two ends, one of said two ends is 
attached to other said opposite side of said housing 
whereby said pivot point of said second bar is 
aligned with said pivot point of said first bar; and 
a strap connected to said other ends of said first and 
second bars. 
10. A prosthetic hand as recited in 9, wherein 
said strap, further comprises an adjustable means fas- 
tened to said strap for tightening said strap. 
11. A prosthetic hand as recited in claim 10, wherein 
end whereby said first bearing surface 40 said adjustable means, comprises a nylon fabric which 
ing; What is claimed is: 
1. A prosthetic hand, comprising: 
a cuff, said cuff having an open end and a closed end; 
a stem, said stem having a plain end and a cam end, 
said plain end is attached to said closed end of said 
cuff; 
a housing pivotally mounted on said stem whereby 35 
said stem is free to pivot within said housing, said 
housing having two opposite sides; 
a first finger pivotally mounted to said housing, said 
first finger having a first bearing Surface and a first 
rides against said cam end of said stem; 
a second finger pivotally mounted to said housing, 
Said second finger having a Second bearing surface 
and a second Clamping end whereby said second 
bearing surface rides against said Cam end of said 45 
stem; hole; 
against said cam end of said stem; and 
housing whereby said Cuff Can Pivot said stem 50 
within said housing moving said first clamping end 
relative to said second clamping end by action of 
said cam end rotating against said bearing surfaces. 
2. A prosthetic hand as recited in claim 1, wherein 
said attachment of said plain end of said stem to said 55 
cuff, comprises: 
a cylindrical anchor attached to said closed end of 
said cuff and enclosing said plain end of said stem; 
and 
a pin, said pin extending from said cylindrical anchor 60 
into said plain end of said stem whereby said stem 
is locked to said cylindrical anchor. 
3. A prosthetic hand as recited in claim 1, wherein 
said attachment of said plain end of said stem to said 
cuff, comprises: 
a cylindrical anchor attached to said closed end of 
said cuff and enclosing said plain end of said stem, 
said cylindrical anchor having a threaded hole; and 
30 
can be fastened to itself. 
12. A prosthetic hand, comprising: 
a cuff, said cuff having an open end and a closed end; 
a cylindrical anchor attached to said closed end of 
said cuff, said cylindrical anchor having a threaded 
means for holding said bearing surfaces of said fingers 
a brace attached to said housing for Stabdhiing said 
a set screw within said threaded hole of said cylindri- 
a stem, said stem having a plain end and a cam end, 
cal anchor; 
said plain end is inserted within said cylindrical 
anchor and is locked to said cuff by said set screw; 
a housing pivotally mounted on said cylindrical an- 
chor whereby said stem is free to pivot within said 
housing, said housing having two opposite sides; 
roller bearings located between said cylindrical an- 
chor and said housing to facilitate rotation of said 
stem within said housing; 
a first finger pivotally mounted to said housing, said 
first finger having a first bearing surface and a first 
clamping end whereby said first bearing surface 
rides against said cam end of said stem, said first 
clamping end further having a roughened surface; 
a second finger pivotally mounted to said housing, 
said second finger having a second bearing surface 
and a second clamping end whereby said second 
bearing surface rides against said cam end of said 
stem, said second clamping end further having a 
roughened surface; 
65 
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5,02 1,065 
5 
means for holding said bearing surfaces of said fingers 
against said cam end of said stem; 
a first bar having two ends and also having a pivot 
between said two ends, one of said two ends is 5 
attached to one of said opposite sides of said hous- 
ing; 
whereby said pivot point of said second bar is 
aligned with said pivot point of said first bar; 
strap connected to said other ends of said first and 
second bars; and 
a nylon fabric which can be fastened to itself is at- 
tached to said strap for adjusting size of said strap. 
13. A prosthetic hand as recited in claim 12, wherein 
said means for holding said bearing surfaces of said a second bar having ends and having a pivot fingers against said cam end of said stem, comprises an 
* * * * *  
between said two ends, one of said two ends is 10 elastic band wrapped around said fingers. 
attached to other said opposite side of said housing 
15 
20 
25 
30 
.35 
40 
45 
50 
55 
60 
65 


Rotationally actuated prosthetic helping hand

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