Energy responsive prosthetic leg

A prosthetic leg component substantially encompasses the tibia or shin portion of the leg and is removably attached to any one of several available prefabricated prosthetic foot devices. Included is a substantially L-shaped member providing for efficient kinetic recoil energy about the ankle upon application of a given load on the device which allows for torsional replication about the tibia while simultaneously providing medial-lateral stability for the user.

BACKGROUND OF THE INVENTION 
FIELD OF THE INVENTION 
This invention relates to prosthetic devices or artificial limbs, and more 
particularly, to a device for use either by below-knee or above-knee 
amputees. 
The typical or normal walking cycle includes two phases: (a) stance or 
weight bearing phase and (b) swing phase. Stance phase initiates the 
instant the heel contacts the ground and terminates when the toes push off 
the ground (toe-off). Swing phase initiates at toe-off and terminates at 
heel contact. 
It has been noted in prior art leg prosthesis that complete prosthetic 
restoration of normal functioning during "push-off" is difficult, if not 
impossible. A proprioceptive sense of knee position is necessary, as well 
as an active or responsive source of energy in the ankle. 
The present invention will be understood to be directed toward a prosthetic 
leg which is inexpensive in construction and which may be removably 
secured to any one of a multiplicity of available prosthetic foot devices 
and whereby, upon placing a load thereon, initiates moments about the knee 
and ankle, respectively, to transform those respective moments and provide 
for an active source of energy about the ankle. 
The method and construction of the invention is more fully described 
herein. 
DESCRIPTION OF THE PRIOR ART 
Various prior art leg prosthesis and the like, as well as the method of 
their construction in general, are known and are found to be exemplary of 
the U.S. prior art. They are: 
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U.S. Pat. No. Inventor 
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4,547,913 Phillips 
4,463,459 Shorter et al. 
4,461,045 Shorter et al. 
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U.S. Pat. No. 4,547,913 issued to V. L. Phillips discloses a composite leg 
and foot prosthetic device which utilizes a resin impregnated high 
strength filament structure for the leg portion, foot portion, and heel 
portion, all three of which are rigidly joined at the ankle. 
U.S. Pat. No. 4,463,459 issued to J. J. Shorter et al. discloses an 
artificial leg having a ball and socket ankle joint connected together and 
clamped over the ball by a turnbuckle ring. 
U.S. Pat. No. 4,461,045 also issued to J. J. Shorter et al. discloses an 
artificial leg which is seen to provide relatively more resistance to 
dorsi-flexion than to plantar-flexion. 
These patents, or known prior art uses, teach and disclose various types of 
prosthetic devices of sorts and of various manufactures, and the like, as 
well as methods of their construction; but none of them, whether taken 
singly or in combination, disclose the specific details of the combination 
of the invention in such a way as to bear upon the claims of the present 
invention. More specifically, none of the prior art inventions disclose a 
prosthetic leg which is selectively attachable to any one of a variety of 
prefabricated artificial foot members, and furthermore provides for an 
active source of energy about the ankle. This active source of energy, 
provided for in the present invention, allows for simulation of normal 
gait and improved prosthetic restoration relative to the "Push-off" phase 
of the walking cycle. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide for a leg prosthesis which 
is safe in use and which is selectively attachable to any one of a number 
of available prefabricated artificial foot members, e.g., prosthetic foot 
devices having energy responsive elements (springs) therein. 
Another object of the present invention is to provide for a prosthetic leg 
which initiates moments about the knee and ankle portions and transforms 
these moments into an active source of energy about the ankle. 
A further object of the present invention is to provide for a prosthetic 
leg which simulates the properties involved in the two stages of the 
normal walking cycle, i.e., stance phase through swing phase. 
Another object of the disclosed invention is to provide for a prosthetic 
device which simulates the interaction between the knee and ankle, 
respectively, of a normal leg during a normal walking cycle. 
A still further object of the present invention is to provide for a 
complete prosthetic system which will decrease the amount of stress on the 
traumatized area, thereby providing for long term prosthetic 
rehabilitation. 
Another object of the present invention is to provide for a prosthesis 
which is psychologically as well as physiologically acceptable to the 
user. 
With these and other objects in view which will more readily appear as the 
nature of the invention is better understood, the invention consists in 
the novel construction, combination and arrangement of parts hereinafter 
more fully described, illustrated and claimed, with reference being made 
to the appended drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, wherein like numerals refer to like parts, 
there is seen in FIGS. 1 and 2 the prosthetic leg 10, including a 
substantially L-shaped resilient member 11 rigidly affixed to a stump 
receiving member or socket 50, at one end thereof, and removably attached 
to an artificial foot member 30 at the opposite lower end thereof. 
A distinct advantage, as more fully described below, of the prosthetic leg 
10 lies in its interchangeable capabilities with respect to currently 
available artificial foot members, such as foot member 30. The prosthetic 
foot devices available in today's prosthesis environment are seen to 
include fastening means, such as pin member 36, wherein the foot members 
30 are readily attached to, and removed from, the residual ankle area. The 
present invention complements this technology by providing for user 
selective attachment of a multiplicity of artificial foot members. As seen 
in FIGS. 1A and 1B, disparate artificial or prosthetic foot members, such 
as foot members 30, 30A, and 30B, are illustrated which have different 
spring coefficients. FIG. 1A illustrates an artificial foot member 30A 
which includes a horizontally disposed leaf spring-type mechanism 34A, 
while the device of FIG. 1B illustrates a foot member 30B including a 
vertically disposed helical spring mechanism 34B. Either may be 
selectively provided, or chosen, in accordance to each amputee's physical 
needs and capabilities. For example, a patient experiencing difficulty 
during the "push-off" phase of the walking cycle, may require additional 
reactive loads substantially spanning the lower plane of the "foot" , in 
which case, a device such as that shown in FIG. 1A would produce the 
desired effect, while the user simulates conventional walking procedure. 
Referring now to FIG. 2, the device 10 includes a substantially L-shaped 
shin member 11 including a resilient vertical member 14 integral with a 
lower ankle portion 22 in turn joined to an elliptic base member 12. A 
bore 16 is provided so that, as previously mentioned, a multiplicity of 
readily available artificial foot members, e.g., helical spring type 30B, 
may be selectively and removably affixed to the L-shaped shin member 11. 
Pin member 36 is also provided, and is seen to substantially extend from, 
and pass through, the lower portion of the prosthetic foot 30. The pin 
member and foot will be seen to be secured to the shin member 11 by 
conventional fastening means, such as nut member 38. 
Alternately, a second embodiment of the L-shaped member 20 is shown in FIG. 
2A and includes an ankle portion 22' essentially disposed in perpendicular 
relationship to the resilient shin member 24'. Herein, the L-shaped member 
20 is seen to provide controlled medial-lateral flexion of the prosthetic 
leg 20 upon applying a load thereon during use of same. In each L-shaped 
member embodiment, the shin member 14, 24', will be understood to comprise 
a transversely disposed flat, blade member. 
The geometric shape and recoil properties provided by the device 10 are 
essential for the two stages of the walking cycle, i.e., stance phase and 
swing phase. The device is seen to simulate both "push-off" and forward 
propulsion at the end of the midstance phase. Furthermore, dorsiflexion is 
important in preventing toe drag after "push-off" and thus requires 
approximately 15-20 degrees reflection angle with respect to the shin in 
order to provide substantial kinetic energy about the ankle, thereby 
initiating the required angular movements in the succeeding swing phase. 
The acute angle formed between the lower portion of the vertical member 14, 
24' and the elliptical base member 12 provide for an active source of 
energy in the ankle portion 22 of the L-shaped member 11, 20 during the 
walking cycle. Herein, upon placing a load on the prosthetic member, the 
device 10 allows for intiation of knee flexion and assists in the swing 
phase of the cycle. It should be emphasized here that complete prosthetic 
restoration in "push-off" phase is difficult to obtain. In prior art 
inventions an active source of energy about the ankle was not provided 
for. The present invention alleviates this lack of active energy by 
initiating moments about the knee and ankle, and also by geometrically 
providing for an energy responsive system, originating at the residual 
stump S and terminating about ankle portion 22 of the device, thus greatly 
enhancing the prosthetic restoration relative to the "push-off" phase of 
the walking cycle as the user's weight is cyclically applied to the shin 
member. 
Another function provided by the L-shaped member 11 of the present 
invention 10 is to simulate the interaction between the knee and ankle of 
the normal leg, wherein the two combine to provide for fluent absorption 
of the shock caused by heel contact and also to maintain a continuous path 
relating to the body's center of gravity during this heel-contact phase. 
As seen in FIGS. 4 and 5, the present invention further discloses a 
composite energy responsive prosthetic leg 100, including user variable 
pressurized air members or bellows 64. Herein, socket member 62 is 
provided along with a disparate inner bladder 60. The bladder 60 is 
disposed between socket 62 and the residual stump S of the amputee. The 
bladder 60 acts as a socket liner. Its variable volume allows for a 
comfortable, adjustable fit for the stump. Prior to the use of this 
variable volume air bladder 60, stump socks of single, triple and 5-ply 
nature were used to adjust the fit between the socket 62 and the stump of 
the patient's leg. The atrophy of the stump over time would require the 
addition of more stump socks. The bladder 60 provides a variable size 
adjustment means. The bellows 64 as seen in FIG. 4, may be displaced 
adjacent the heel portion of the prosthetic foot 30, or alternately, may 
be incorporated therein as shown in FIG. 6 (working in conjunction with 
the S.A.C.H.--Soft Ankle Cushioned Heel--of available prosthetic foot 
devices). An expansion conduit 66 and contraction conduit 68 provide for 
the supply and release of pressurized air between the pliable bladder 60 
and dual-bellows members 64. This may be accomplished via user regulated 
expansion valve 70 and user regulated contraction valve 72, respectively, 
both of which are disposed in readily accessible user areas, such as the 
medial-lateral portion of socket member 62 of the apparatus. The user can 
pump up the bladder 60 by opening expansion valve 70 and striking the heel 
of the prosthetic foot 30 against the bellows 64 to pump up the bladder to 
a desired fit. Closing valve 70 maintains the pressure fit. Opening valve 
72 will reduce the bladder 60 size by releasing air. 
Upon complete assembly of the composite energy responsive prosthetic leg 
100, as illustrated in FIG. 5, the device allows not only for the dynamic 
and geometric attributes proposed earlier, i.e., efficient initial loading 
moments, posterior plantar flexion and dorsiflexion, increased and much 
desired medial lateral stability, along with an active source of energy 
about the ankle portion, but also provides for decreased stress on the 
traumatized area, which is required in a for long term prosthesis. 
The cosmetic value of prefabricated prosthetic feet, along with the advent 
of skin-toned foam rubber latex covering allow for a prosthesis which is 
natural looking, and therefore psychologically as well as physiologically 
acceptable to the user. 
The foregoing is considered as illustrative only of the principles of the 
invention. Further, since numerous modifications and changes will readily 
occur to those skilled in the art, it is not desired to limit the 
invention to the exact construction and operation shown and described, and 
accordingly, all suitable modifications, and equivalents which may be 
resorted to, fall within the scope of the invention.