CA2063504C - Foot prosthesis having auxiliary ankle construction - Google Patents
Foot prosthesis having auxiliary ankle constructionInfo
- Publication number
- CA2063504C CA2063504C CA 2063504 CA2063504A CA2063504C CA 2063504 C CA2063504 C CA 2063504C CA 2063504 CA2063504 CA 2063504 CA 2063504 A CA2063504 A CA 2063504A CA 2063504 C CA2063504 C CA 2063504C
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- foot
- section
- ankle
- prosthesis
- forefoot
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Abstract
A prosthetic foot characterized by a forefoot portion having a heel portion demountably and interchangeably connected thereto. The forefoot portion and heel portion are fabricated from polymer impregnated and encapsulated laminates or other reinforcing fiber, including such materials as carbon fibers and/or fiberglass or synthetic fibers such as Kevlar. interchangeablility of heel and forefoot portion permits interchangeability of heel and forefoot portions to match the weight, stride and activity schedule of the wearer utilizing the prosthetic foot. Auxiliary ankle member and wedge means between the forefoot portion and the heel portion provide additional adjustability.
Description
FOOT PROSTHESIS HAVING AUXILIARY ANKLE CONSTRUCTION
Backqround of the Invention:
This invention relates to foot prostheses in general, and speclflcally to a prosthetlc foot characterized by a unltary foot and heel constructlon, and/or an auxlliary ankle construction whlch permlts the flexlblllty of the prosthesls to be selectlvely determlned and easily changed. The inventlon also includes an improved coupllng for attachlng sald foot prosthesls to an auxiliary pylon tube.
The prior art is replete with various types of mechanical devices purporting to solve the foot prosthesis problem. Typical of early devices is U.S. Patent No. 2,075,583 issued June 30, 1937 naming Lange as lnventor, whlch incorporates a rubber form mounted ln operatlve relationshlp with a rigid metalllc core. Exemplary of the latest developments ln the fleld ls U.S. Patent No. 4,645,509 naming Poggl as inventor and issued February 24, 1987, whlch teaches a prosthetic foot incorporatlng a monollthlc keel or beam of relatlvely masslve proportions lntended to react to the load of an amputee's body durlng walking, running, iumping, and the like and to rel'ease the resultant stored energy to create foot lift and thrust complementlng the amputee's natural strlde.
., ~
- However, each of the prior art devices has significant deficiencies; specifically, the component parts of the prosthesis, as in Lange, are too heavy and too rigid or, as in Poggi, are too masslve and monolithic to respond properly to the nuances of stress-response gradients characteristic of the human foot.
One of the primary factors which has inhibited the creation of a truly successful prosthetic foot has been the fixation of the prior art with the duplication of the structural aspects of the skeletal and muscular components of an actual human foot. In many instances, as exemplified by Poggi '509, mentioned hereinabove, even the toes of the foot are attempted to be duplicated by providing simulacra thereof. It is this fixation upon the mechanical elements of the human foot which has restricted the art to an attempt to duplicate the human foot components, a tendency which is particularly exemplified in U.S.
Patent No. 3,335,428 issued August 15, 1967 naming Ga~dos as inventor.
My U.S. Pat. No. 5,037,444, issued August 6, 1991, 'discloses certain concepts relating to a prosthetic foot characterized by a forefoot portion and a heel portion which may be permanently or demountably associated with each other whereby both the forefoot portion and the heel portion can be readily exchanged with correspondingly constructed heel and forefoot portions. This exchangeability permlts size B
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adjustment or accommodation of different spring rates to suit the size of foot of the amputee or the stride and weight of the amputee, yielding an almost infinite range of combinations of spring rate and size to the amputee, and allowing a natural stride and resilience of gait which has to been obtainable by prior art prosthetic devices. The invention of my U.S. Pat.
No. 5,307,444 utilizes a horizontal attachment surface for attaching the prosthesis to a pylon, however; this horizontal attachment surface imparts some limitations on size, weight and performance of the prosthesis, as well as in difficulty and expense of manufacture, which limitations are not present in the instant invention.
Summary of the Invention:
In one embodiment my invention provides a foot prothesis which is characterized by a fore-foot portion and a heel portion which may be permanently or demo~ntably associated with each other, with the forefoot portion having an upwardly extending attachment section providing ease of manufacture and resistance to rotation, whereby both the forefoot portion and the heel portion can be readily exchanged with correspondingly constructed forefoot and heel portions to provide size adjustment or accommodation of different spring rates to suite the size of foot of the amputee or the stride and weight of the amputee, and further adjustments can be made by the use of an auxiliary ankle spring member. Therefore, an almost infinite combination of spring rate and size can be provided CA 02063~04 1998-03-0~
to the amputee, achieving a natural stride and resilience of gait, which has not been obtainable by prior art prosthetic devices.
In another embodiment the invention provides a prosthetic foot of the aforementioned character having an interchangeable or permanent forefoot portion which has a toe section, an arch section, a curvilinear ankle section, and an upwardly extending attachment section, all constructed without the necessity of tapering of the thickness thereof. Also incorporated in the aforementioned foot is a heel portion which has an attachment section secured to the intersection of the arch and toe sections of the forefoot portion and a heel section extending beyond the curvilinear ankle and attachment sections of the forefoot portion. The heel section extends beyond the curvilinear ankle and attachment sections of the forefoot portion.
As previously indicated, the forefoot portion can be provided in different sizes and spring rates, and an auxiliary ankle member may be utilized, thus permitting the gait, weight, and activity level of the amputee to be readily accommodated. Correspondingly, the forefoot portion can be demountably associated with the heel portion of the foot to permit different sizes of heel portion having different spring rates to be mounted in operative relationship with the forefoot portion.
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In another embodiment the invention provides a prosthetic foot of the aforementioned character in which both the forefoot and heel portions of the foot are fabricated, and the auxiliary ankle may be fabricated, from superimposed laminates maintained in operative relationship by an encapsulating polymers, and further in which said toe, arch, ankle and attachment sections of said forefoot portion, said heel section of said heel portion, and said auxiliary ankle attachment are susceptible to bending stress determined by the number of the laminates and polymers in the respective toe, arch, ankle and attachment sections of said forefoot portion, in said heel section of said heel portion, and in said auxiliary ankle attachment. Thus, the various portions and sections thereof are encapsulated in a polymer and capable of spring stress response as ankle loads are imposed thereupon during the utilization of said foot.
In another embodiment the invention provides a prosthetic foot of the aforementioned character, having a forefoot portion which consists of continuous, integrally and simultaneously formed toe, arch, ankle and attachment sections, said sections being fabricated as a unitary structure by polymer impregnation of superimposed reinforcing laminae maintained in the desired configuration of said forefoot portion and said toe, arch ankle and attachment sections being capable of spring stress generated energy storage whereby the subjection of the toe sections to bending moments will cause uniform transmission of spring stress CA 02063~04 1998-03-0~
through said arch section and through said curvilinear ankle section of said forefoot portion to said attachment section thereof.
Alternatively, chopped fiber or other suitable reinforcing material may be utilized instead of or in addition to the aforementioned laminates.
In another embodiment the invention provides a prosthetic foot in which the curvilinear ankle section of said forefoot portion has its upper extremity constituted by said upper attachment section and its lower extremity extending into and constituting said arch section, said lower extremity, said curvilinear ankle section and said upper attachment section maintaining an approximately uniform thickness transversely of the longitudinal axis of said sections. Similarly, said heel portion and its various sections are provided with an approximately uniform thickness transversely of the longitudinal axis of said sections.
In another embodiment the invention provides an auxiliary ankle attachment, which is associated with the ankle section of said forefoot portion to increase the resistance of said ankle section to loads imposed upon the toe section of said forefoot portion. The concept of the auxiliary ankle involves the provision of ankle members characterized by different spring rates, which permits the resistance of the ankle section to deflection to be precisely adjusted to the weight, CA 02063~04 1998-03-0~
activity level and other characteristics of the individual for whom said foot is being adjusted.
The polymers utilized to encapsulate the fibrous laminae are characterized by elastlcity and flexibility so that the forefoot and heel portions deflect proportionally to the engagement of said forefoot portion with an adjacent surface, causing the resultant energy to be stored and subsequently released when the gait of the amputee incorporating thrust and lift components results in the utilization of the stored energy and a consequent reduction of the energy expended by the amputee. There is a gradual increase in stiffness as the lever arm of the toe section of the forefoot portion shortens due to gradual deflection thereof.
In another embodiment my invention provides an improved coupling mechanism for attaching a prosthetic foot of the above mentioned character to an auxiliary pylon tube which is in turn attached to the wearer's leg.
In order to impart a cosmetic aspect to the prosthetic foot, after proper fitting of the foot to insure that the forefoot and heel portions and the auxiliary ankle are properly balanced and of appropriate size, the prosthesis may be encapsulated in a suitably shaped foot-like shroud to facilitate the utilization of the prosthetic foot with a conventional shoe. The enclosure must be sufficiently flexible so as not to inhibit the free movement and flexure of CA 02063~04 1998-03-0~
. .
the forefoot and heel portions and the auxiliary ankle of the prosthetic foot, but, because of the inherently resilient and stress-absorbing characteristics of said foot, little dependence is needed upon the ancillary cushioning action of the enclosure.
In another embodiment my invention provides a prosthetic foot characterized by extreme light weight, instantaneous response to imposed loads and correspondingly instantaneous delivery of stored energy when the gait of the wearer indicates that such stored energy is to be released.
Moreover, the foot may be readily mounted in operative relationship with conventional ancillary pylons and couplings, and can be fine-15= ~
~=
~tuned by the blending of the forefoot and heel portions andauxiliary ankle characteristics to achieve the ultimate ln operatlve response to the needs of the wearer.
Consequently, the wearer of the foot may engage in a wlde variety of actlvities which were precluded ln the past because of the structural llmltatlons and correspondlng performances of prior art prostheses. Running, ~umping and other activities are sustained by the foot and it amy be utilized ln the same manner as the normal foot of the wearer.
In accordance with one aspect of the lnvention, there is provided a foot prosthesis adapted to be demountably secured to a vertlcally orlented rlgld pylon member for provldlng kinematlc support to an amputee relative to the ground, comprlslng:
a forefoot member detachably secured to and extendlng relatively downward and forward from the rigld pylon member. The forefoot member is formed of a resillent and flexlble material and ls adapted to store and release energy by bending ln response to a downward compressive force exerted by the amputee. The forefoot member foot comprlses:
a substantlally vertically oriented upper attachment sectlon adapted to detachably secure sald forefoot member to the rlgid pylon member;
a relatively stiff ankle section capable of resisting excessive bendlng of the forefoot member, the ankle section ls configured to bend in a manner analogous to the manner in which ~-a normal human foot pivots about a normal ankle ioint;
a relatively compliant toesection extending relatlvely forward from the ankle section defining a forward lever arm of said foot prosthesis; and a heel member detachably secured to and extending relatively downward and rearward from said forefoot member defining a rearward lever arm of sald foot prosthesis.
The forefoot member can be readily detached from the rigid pylon member and is interchangeable with like forefoot members having different resiliency characteristics such that a wide range of varying actlvity levels may be sustained ln a single foot prostheses.
In accordance with another aspect of the present invention, there is provided a lower limb prosthesis adaptable to a socket fitted to the stump of a lower-limb amputee for providing resilient kinematic support to said amputee during normal walking, running and ~umping activities, comprising:
a substantially rigid tubular pylon member having a proximal end adapted to engage said socket and a distal end extending substantially vertically and termlnating at about the location of said amputee's normal ankle ~oint, said distal end having front and rear sides; and a detachable flexible foot prosthesis comprising a spring-like foot member adapted to be selectively attached to said distal end of said tubular pylon member according to a particular desired activity or a particular desired degree of kinematic resilience, said foot member further comprising:
9a _ an upper attachment sectlon havlng a substantlally vertlcal mountlng surface adapted to closely recelve a correspondlng substantially vertlcal mountlng surface dlsposed on said rear side of said distal end of said tubular pylon member;
an intermediate ankle section formed integrally wlth and curving substantially continuously downward and forward from said upper attachment section such that bending stress is distributed substantially evenly therethroughout;
a toe section having a proximal end and a distal end, said proxlmal end being formed integrally with said intermediate ankle section and said distal end extending forwardly to correspond to the toe of the user, said toe section curving substantially continuously forward from said proximal end to said distal end thereof such that bending stress is distributed substantially evenly therethroughout, said toe section meeting the ground at a point near said distal end of sald toe section to define, together with said ankle section, a forward lever arm for said foot member for returning substantial energy to said ~0 user during toe off; and a heel member extending substantially contlnuously rearward and downward from a polnt tangentlal to sald lntermedlate ankle sectlon such that bendlng stress is distrlbuted substantlally evenly throughout sald heel member, sald heel member providing a rearward lever arm for said foot member;
sald heel member and said toe section providing substantially the sole support for loads incurred by sald flexlble foot prosthesls 9b -durlng heel strike and toe off, respectlvely;
whereby said foot member can be readily detached from said tubular pylon member and is interchangeable with like feet members having different resiliency characteristics without having to change or adiust sald socket or the length of said tubular pylon member, such that a wide range of varylng actlvlty levels may be sustained in a slngle prosthetic device.
In accordance with yet a further aspect of the present invention, there is provlded a lower limb prosthesis adaptable to a socket fitted to the stump of a lower-limb amputee for providing reslllent kinematic support to sald amputee durlng normal walklng, running and ~umping actlvltles, comprlslng:
a substantlally rlgld tubular pylon member having a proximal end adapted to engage said socket and a dlstal end extendlng substantially vertically downward and terminatlng at about the locatlon of sald amputee's normal ankle ~olnt; and a detachable flexlble foot prosthesls comprlslng a sprlng-llke foot member adapted to be selectively attached to sald dlstal end of said tubular pylon member according to a particular desired activity or a particular desired degree of kinematic resilience, said foot member further comprising:
an upper attachment section having a substantially vertically oriented attachment surface adapted to attach sald ~5 foot member to sald tubular pylon member;
an lntermedlate ankle sectlon formed lntegrally wlth and curvlng substantially continuously downward and forward from said upper attachment section such that bending stress is i ,~, CA 02063~04 1998-03-0~
distributed substantially evenly therethroughout, said intermediate ankle section providing substantially the sole support for all vertical, transverse and torsional loads transmitted through said tubular pylon member to said flexible foot prothesis;
a resilient toe section formed integrally with said intermediate ankle section and curving substantially continuously forward therefrom such that bending stress is distributed substantially evenly therethroughout, said toe section defining a forward lever arm for providing substantially the sole support for all vertical, transverse and torsional loads transmitted through said flexible foot prosthesis during toe off; and ~5 a resilient heel member extending substantially continuously rearwardly from said intermediate ankle section such that bending stress is distributed substantially evenly throughout said heel member, said heel member defining a rear lever arm for providing substantially the sole support for all vertical, transverse and torsional loads transmitted through said flexible foot prosthesis during heel strike;
whereby said foot member can be readily detached from said tubular pylon member and is interchangeable with like feet members having different resiliency characteristics without having to change or adjust said socket or the length of said tubular pylon member, such that a wide range of 9d CA 02063~04 1998-03-0~
varying activity levels may be sustained in a single prosthetic device.
Other embodiments and modifications of the invention will be apparent from the following specification and the accompanying drawings, which are for the purpose of illustration only.
Brief Descri~tion of the Drawinqs:
FIG. 1 is a side elevation view of portion of a prosthesis constructed in accordance with the teachings of the invention;
FIG. 2 is a partially sectional plan view, taken along line 2-2 of FIG. 1;
FIG. 3 is a front elevation view, taken along line 3-3 of FIG. 2; and qe 2063~04 FIG. 4 i~ a partially sectional side ele~ation ~iew, taken along l~ne 4-4 of ~IG. 2.
Pescri~t;on o~ Pr~ferred F~?di~
Referring to t~e dxawin~c, and particularly to FI~S. 1 and 2 thereof, ~ ~how a foot prosthe8i~ lO con-~tructed in accoraance with the toAc~gs of the invention and including a forefoot portion ~0 an~ a ~eel portion 84 operatively and demountably connectea to each other by bolt an~ nut combinations 104 associated wit~ load-~ransmitting metallic plates lO~. If indicated, the forefoot and heel portions can be permanentl~ Se_~L~ to each other, as by epoxy adhesive or the like.
The for~oot portion 80 of the pro ~hesis lO in-clude~ a substanti~l~y rigid upper a~tachment ~ection 92 r a cur~ilinear a~kle sRction 94, ~n arch ~ection 96 and a toe section 82. The sections 92, 94, 96 and 82 of the ankle portion 8~ are preferably formed integrally with one another and simultaneously by 5he incorporation of a plurality of laminae embedded ~n a hardened, flexible polymer. Altern~-tively, chopped fiber or other suitable reinfor~ing materialmay be ~t~l~zed instead of or in addition to the afore~en-tion~d laminae.
,.
The attachment ~ection 92 inçoL~o~ates two cen-trally-lo~ated openings 88, FIG. 4. The attachment se~tion 92 i~ ~ubstantially rigid and capable of sust~ining tor-sional, imp~ct and other loads i~pressed thereupon by t~e an~le portion 80 and heel portion 84 of the pro~thesis. In additio~, the inherent rigidity of the attachment section 92 cause~ t~e e~fecti~e transm~sion of the aforesaid load~ ~m-posed theLeupG~I to a ~uita~le ancillary prost~etic py~on 30, by bolt and nut com~inations 98 assembled thr~ugh openings 88 ~o a pylon coupling 9~. A s~rew loo or other suita~le attachment means Be~ S the anc~l~ary pylon 30 in the cou-pling 90.
In the partlcular embodiment o~ ~IGS. 1-4, the auxili~ry ankle 86 is mounted b~tw~en the coupl1ng 90 and 1~ ankle por~ion 80, and ~s ~ec~L~d in operative relat~onship with the ankle portion ankle se~tion 94 through the use o~
centrally-loçated or6~n7~ in an atta~hment section 1~2 o~
the ankle member 86, wh~ch o~o~;n~c are substantially aligned with o~in~s 88 of t~e ankle portion attach~ent section 92. Bo~t ~na nut combinations 98 retain the variou~
com~G,.2nts in the aforecaid operati~e relationship. Al~er-nati~e ~h~mentS would in~lu~e securing the aux~liary an-kle 86 to a rearwa~d ~urface o~ the attachment section ~2.
In the preferred e~bodi~ent, bolt and n~7t combina-tions 104, in conj~nction with the load-~istributing metal-1ic plate~ 106, serve to sec~re the heel port~on 84 in oper-ative re~ationchip with ths forefoot portion 80 of the pros-t~esis. Thi~ mode o~ affixation facil~tates the assembly ordismounting of ~elected heel portions 84 in operati~e rela-tionship with selected foxe~oot portions 80, thus per~itting a wide range of differen~ ~izes and stress load r~on~e characteristics to be r~lated to each other to accomplish the optim~m functional co~l~O~,or~nce between the forefoot and heel portions ~0 a~d 84.
An auxil~ary an~le me~ber 86 can be util;z~d to decrease ~he flexibility of the ~ore~oot heel porti~n 80.
The ~Y~ ry ankle 86 i~ form~d fro~ fibrous la~inate~ of the 6ame c~arac~er as the ~arious portionf of ~he pro~the~;is 10. In the prefsrred s~bodimsnt, the auxiliary ankle 86 in-c~,~oYate~ an atta~hment ~ection 102 which is operat~vely associated wi~h the couplin~ 90 and the upper attachment ~ection 92 of t~e forefoo~ portion 80, and pre~erably there-20 beL~raes~. The auxiliary an~le 86 is preferably S~L~ inoperative relatiQ~ r with ~he curvilinear ankle se~tion 94 of forefoot portion 80 through the aforementionQd assembly of the coupling 90 with the bol~ and nu~ combinations 98.
On its end opposite ~rom the attachment section ~2, ankle member 8~ ~as a tapered section 1~8 which provide~ a varying flexibility along the length of the ankle member 86 and al~o lessen~ the likelihood that the a~kle member 86 will be un-desirably ~nagged or restrained in it~ cooperat~e rela-s tionship with ~orefoot ~oxtion 80 and the cos~etic cover o~
the prosthesi~, ~ore thG~ vuy~ di~cu~e~ beloW. In alter-native e~bodiments, as will be understood by tho~e skilled in tne art, ~uch tape~ing is not required i~ order to prac-~ice the invention, and accor~in~ly, the ankle member 86 can be provided with a xelat~ely uniform thio~ along the length thereof.
In the preferred e~odi~ent, the auxiliary ankle ~e~er 86 is se~e~ against the ~elatively internal radius of the curvilinear an~le section 94, so that t~e anticipated u~war~ deflection of a toe section ~2 of the for~foot por-tion 80, as more t~oroughly described be~ow, will ev~ ually cause de~ormation o~ t~e auxiliary anXle 86 as well as de-formation of t~e an~le section 94, e~fectively combining the deformation resistance and el,~.yy s~orage ch~racteri~tics of the auxiliary an~le ~em~er 86 with tho~e of the ankle sec-tion 94. Alte~native em~od~ment~ would includQ securing the auxi~iary ankle 86 ~o the rearward surface of the attachment ~ection 92 and further securing the auxiliary ankle apered section 108 to an under 6urfac~ 62 of the anXle ~ection 9~
206~04 in order to achieve the aforedescribed desirsd com~ination of the deformation resistance and energy ~torage character-istics of the auxil~ary ankle me~ber 86 with tho~e of the ankle section 94.
The auxilia~y ankle ~ember 86 can be pro~ide~ wit~
different number6 of laminates to ma~e it ~ore or les~ co~-pliant to loads ~ransmitted throug~ the ankle ~ec~ion ~4.
Con~equently, w~en con~ronted with various anomalies in an amputee, such as over~eight or exc~ss ac~ivity levels, the ba~ic structure of tne forefoot portion 80, and mo~e partic-ular~y the ankle section 94, can be materiall~ modi~ ed to proYide ankle portion action wh~c~ is precisely ad~u~ted to the needs of the amputee. Moreover, a variety of auxiliary an~le membexs B6 can be mad~ ~ailable to an ampuSee, allow-ing the flexibility of the prosthesi~ to be ~djusted on the ~asi~ of the particular activity which the ~mput~e i6 under-taking~
As previou~ly ment~oned, a cosmetic cover, not shown, can be pro~ided to ~hroud the prosthe~i~ 10 a~ter t~e optimum assemblage of the forefoo~ and heel portions 80 and 84 and any ~xiliary ankle member 86 has ~een acco~pli~ed.
Unlike prior art construction~, hc~ , the cosmetic cover, which may be formed of low-density formed polymer, i5 not regu~red to ser~e any anc~llary shoc~-absorbing or other stre~s-isolating f~nction since all of ~he loads im~G~6A
upon the prosthesi~ ~an be a~sorbed, transmitted and re-as~erted in a manner to be descri~ed in grQater detail be-low.
The bolt and nut combination~ 104, in conjunction with ~he load-di~ri~uting metallic p~ate~ ~06, ser~e to se-cure the heel portion 84 in operat~ve relation~p with the forefoot portion 80 of the prosthesis.10, a~ b~st shown in FIGS. 1-2 of t~e drawings. The aforesaid mode of affixation facilitate~ the ~ssembly or dismounting of ~elected heel portions 84 in operativ~ ~elationship with selected forefoot portion~ 80 of t~e pros~hesis 10, thu~ permitting a wide range of di~ferent eizes and stre~s load response char-acteristics to ~e ~elated to each otber t~ accompl~sh the optimu~ functional cG L~on~le~ce ~etween the forefoot a~d heel p~rtions 80 ana 84 to ac~ommodate to the m~ximum extent the needs of ~he wearer of the prosthesis, and, al~o, to pro~ide for a proper mating of the prosth~sis 10 with 8 ~e-lected, ancillary py~on 3~ or the like.
The ~orefoot portion 80, as ~est ~own in ~IG. 1 of t~e drawings, includes a toe Qection 82, an arch sectioh g6, a curvilinear ankle section 94, and an a~tac~ment sec-tion 9~. T~e heel portion 84 in~lude~ an attachment se~tion 22 and a heel sec~on 28 which preferably has its rearwaxd 206350~
extre~i~y 56 ext~n~ing beyond an ~xtreme rQarward ~urf~ce 58 of ~e forefoot portion attachmen~ section 92 of the pros-thecis 10. Mating ~ores, not shown, in the arch section 96 of ~e forefoot por~ion 80 and the heel portion 84 ~eceive the re~pective bolt and nut combinations 104 to pro~i~e ~or t~e aforesaid facility in a~embling and ~ rcmbling of the forefoot and heel portions 80 and 84. In the p~efe~red emb~diment, the various ~ection~ of the forefoot port~on 80 are all constructed withou~ the necessity of tapering ~f the thickne~s thereof, alt~ough tho8e skill~d in the art will understand th~t the invention ~ not limited to such non-ta-pering ~n~uction.
Interpo~ed between ~he under surfa~ 62 of the an-~le sec~ion 94 of the heel por~on 8~ and an upper sur~ace 64 of the heel section 28 is a resilient, spring action function ~lock 70 of wed~ ape~ configuration to ~etermine the le~er arm of t~e heel ~ection 28 and ~olate the under surface 62 of t~e anXle section 94 and ~he U~L surface 64 of the heel section 28 fro~ each other. T~e fun~tion block 70 may ~e fabricated fro~ a wide ~a~iety of r~silien~ mate-rials, including natural and synthetic ~bbers or ~e like.
The materi~ls ~rom wh~ch the ~orefoot portion 80 ~nd heel portion 84 and the auxiliary anXle 86 are fabri-ca~ed ~us~ ~e such ~s to pro~ide an energy-storing, re-206350~
silient, spring-lik~ effect. ~hi# ic nece~sary because each engagement of the prosthecis 10 with an adjacent ~urface im-precse~ compression, torsional and ot~er loads upon the pro~thesis 10 which m~st be stored within ~e prosthe~is and then, dependent upon ~he stride o~ the ~earer, ~e reim-pressed upon said surface to achie~e a natural stride con-foxming, ideally, în all re~ s to t~e stride of the unim-paired l~mb o~ ~he w~arer of the ~rost~e~is 10.
~e forefoot and hee~ portions 80 and 84 and the a~xiliary ankle 86 of ~he prosthesis are pre$erab1y molded ~-~ unitary co~ponents and are carefully formed to prov~de for uniform absorption of stress imposed the~u~ . m e configuxat~on of both portlons 80 and 84 i~ o~ utmost impor-tance and the ~l.o~d f~ers, laminates, or other reinforc-lS ing material~, and the poly~er or polymer~ from whi~h theport~ons 80 and 84 are fabricated ~u~t be resil~ent and ca-pa~le of absorbing the compre~sive, torsional and other etre~ses referred to herei~hove and of rest~ring the stored energy created by such s~e~es, in a na~ral ~anner, to the impacted surface w~ic~ orlginally imro~e~ ~u~h ~tres~es upon the pros~hesis 10.
It has been found that there ~ a lim~ted number of polymers capabl~ of s~st~ini~ the significan~ stresses and repetitive loads impose~ upon the prosthes~s 10, partic-'~ 206350a~
ularly in the l~ght of the countless number~ of ~y~les to which the pro~thesi~ 10 is subjected ~uring normal, everyday use .
At present, the best materials for the pro~thesi~
are a composite o~ high-~trength graphite fiber in a hig~-toll7h~C epoxy ther~o6ettin~ resin system. ~here are sev-eral reasons for this: t~ high str~ngth; t2~ gtiffness to weight rat~o o~ graphite as compared to oth~r ~at~rial~; t3) the almost comple~e return of input or stored energy: (4) ligh~ weight; ~5) high fatigue s~rength; and ~) minimal creep. As an alternative material, fiberglassfepoxy is a fair choice, but it is not ~s good as graphite because of lower fatigue st~ength and highe~ den~ity. ~evlar i~ e~en le~s acceptable due to poor compression and shear strength, althou~h it is the lowe~t density of those mentioned~
An i~portant ~spect of t~e polymers and chopped fibers or lami~ates referred to ~ereinabov~ i~ tha~ they are characterized by n~e~o~, but not eY~-r_ci~e, flexural deflec-tion under lo~d, which'characteri~tic permits the ~hoc~-ab-sorption stress lo~ng o~ the pros~he~is 10 while ~R~ntain-ing sufficien~ sta~ility to ~vcn~ the collap~e o~ the forefoot ana heel portions 80 and 84 and She ankle member 8 of the prosthesis 10 while loads are imposed t~ere~.,.
To achie~e the relatively thin ~o~ ruction of the foot and ankle portions 80 and ~4 and the auxiliary ankle me~er 86 of the pro~;thesi~ 10, the afore~aid polymers are utilized in c~njunction with va~ous reinforclng or laminat-ing materialc. Variou~ types o~ fibrous laminae can be uti-lized to achieve the contin~um requ~red by the design of the foot and ankle portions 80 and 84 and the ankle member 86 to ~omplement the stress-ab~or~ing and storing c~aracteri~tics ~f the polymers in which said fibrous lam~nae are em~ A~.
0~ course, t~ere ~s a wide ~ariety of f~brous re-infor~ements in the form of laminae available at the ~l~_cnt ~ime, including such inorganic ~ibers a~ gla~s or carbon fiber~. ~hese inorganic fib~rs are cus~omar~ly pro~ided in tape or s~eet form and can be readily ~uperi~posed in the mold to penmi~ the~ ~o be encapsulated in the selected poly-mer~ As set forth above, the fibers may ~lso be chopped or in ot~er form.
O~iously, the number of superlmposed laminae or other reinforcing laminae ~nd ~hQ lengths thereof, togeeher with the thickness of the en~psulating polymer, deter~ine the stress characteristics of the resultant foot and ankle portions 80 and 84 and the an~le member 86 and, co~Le~ d-ingly, determine the total weig~t o~ She prosthes~s 10. As w~ e apparent ~rom the di~c~lr~ion hereinbeloW, the indi-20635Q~
vidual foot and anXle portions 80 and 84 and an~le member g~
are de~igned to specifically aCCOmmodate individuals having different foot cizes, different weights and different strides and the indi~id~al design of the f~ot and an~le por-tions 80 and 84 and the ankle member 86 pro~ides for matc~-ing, to an extent previou~ly unknown in the art, the natural chara~teri~tics of t~e ~earer'~ uninjured limb.
~urthermore, the function block 70 can be provided in different sizes and in material~ having different ccm-pre~sion character~gtics ~o tha~ the lever ar~ and the cor-r~ ndi~ deflection~ of the heel section 2~ may ~e in-cre~s*d or decrea6ed.
As previously mentioned, the ankls ~ection 94 is formed integrally with the ~pper ~ttachment ~ection 18 and said attachmen~ ~ection constitutes the upper ex~remity of the ankle ~ection ~4, while the ~ nitiat~on of the arch sec-tion 96 of the forefoot portion 80 oonstitutes the lower ex-trem~t~ of the an~le 6ection 94. The configuration of the ankle ~ection 94, in con3unction ~ith the auxiliary ankle ~o member 86, i~ the means whereLy comprQssive lo~ds im~
during impinge~ent of the foot and ankle por~ions 80 and 84 ~pon an adjacent surfaoe are a~~G~L~d and subsequently reim-po~ed upon said ~urface. The an~le portion 94 and the aux-ilia~y ankle member 86 are ~o designed that they Punction, 206350~
s~bstantially, as an an~le joint to permit pi~oting of the forefoot portion 80 thereabout in a manner analogous to the manner in ~hich ~he normal foot pi~o~s about the normal an-~le joint about an axi~ transversely of sAid ankle jotnt.
The radii of curvature of the ankle section 94 and any auxiliary ankle member 86 correspon~ to provide ~or ~he inherent re~liance and deflection of the ~orefoot portion 80 while inhib~ting un~e~ired, excessi~e collap~e of the ~n-kle section 94.
It will ke noted that the attachment ~ection 22 of ~he heel portion 84 i~ substantia~ly rigid and that the ini-t~a~ de~lection of the heel gection 28 v~ c i~mediately adjacen~ t~e rearward extrem~ty 56 of ~aid h~el ~ection, terminating immeaiately adjacent the ~unction block 70. Ob-~iously, a greater length or le~ resilient function block 70 reduces the lever ar~ of the heel seo~ion 28 of the hPel porti~n 84 and co~e~ y re~uces the ~odulu~ of de-fl~ction of caid ankle section, while a smaller l~ngth or more re~ilient function bloc~ 70 incr~ases the lever arm and correspond~ngly inrreases the de~lection of ~e ~eel sectio~
28 under load.
The toe section 82 and heel ~ection ~8 can be pro-~ided In different leng~hs to corr~o,.~ to the size of the foot of the wearer of the prosthesi-~ 10. When ~uch differ-20635~4 ent lengths are pro~ided, corre~.r~dj ng reduction or ~n-crease in the number of la~inae and thic~-eFc of taper o~
the resp2ctive toe section 82 and heel section 28 can be made to provide for t~e proper flexure of said toe and heel section~. It should also ke noted that, e~en with th~
shortest heel section 28, the re~rward ~x~mity 56 thereof preferably projects ~_y~l~ the rearward 6urface 58 of the ~refoo~ portion 80. Co~,~eyu~ ly, ~he stabllizing and ~ ab80rption chara~terist~c~ of the heel section 28 of the prosthe~is lo are always mainta~ned.
Those skilled in the ar~ will understand that many alternative embodiments of the coupling 90 can be con-s~ructed and practiced ~nterc~angeably in oPnnQct~on ~ith the many alte~nati~e embodiment~ of the rest o~ the inven-1~ t~on.
It will, of course, be o~ious to those skilled i~~Ae art that, with re~p~ct ~o any smbodim~nt of th~ ~nven-tion, the ~ibrous reinforcements in ~he form of laminae plies e~ sul~ted ~n the prosthesis may be fayed-o~ tapere~
to acco~plis~ a gra~u~l tran~i~i~n as the number o~ p3ie8 ~S
~e~ in any ~rea o~ the fore~o4~ or heel port~on~
210~e6~eL, if a relati~ely lightweigh~ indi~idual partakes in sports o~ other ac~ ies which ~ub~oc~ the prosthesis 10 to grea~e~ loads, a ~eel or for~foot poxtion . .
., .; .
~
84 or 80 will be ~it~ed which will accommodate for tho3e greater loads.
The an~le ~ection g4 o~ the forefoot portion 80 deflects under load and the auxiliary ankle member 86 si~i-S larly deflect~. Additionally, the toe and arc~ ~ections 82 and 96 of the forefoo~ portion 80, and the heel section 28 of the heel portion 84, de~1ect under ~uch loa~. Therefore, when ~ubjected to vertical compression lo~ds, the ankle sec-tion 94, the auxiliary an~le membex 86, the arc~ sec~ion 96, and the toe and heel sections 82 and 28 absorb such load~.
Consequently, there is no ~tress concentration, e~ther ~n ~he impa~t pha~e when the adj~en~ ~urface is ini-tiall~ contacte~ ~y the wearer of the prosthesis ~0, or when return o~ the a~cumula~ed forces ~tored in the prosthesis 10 is acco~plished.
~he cur~ature of the toe section 82 provide~ fo~
maximum accommodation of said sectio~ during ~ur~ace contact in both the impac~ and del~very ph~se5 of the prosthesi~ 10.
Similar con~iderations apply ~o the curvature o~ th~ heel ~ection 28 of the heel portion 84 of the prosthesis 10. It will be noted tha~ the curva~ures of the toe and heel sec-tionc 82 and 28 pro~ide for rela~vely extended levRr arm~
Which achie~e stability and, a}~o, stres~ ~torage and stres~
reaction.
206350~
The prefer~ed ~ethod of ~anu~acturing t~e ~orefoot and ~eel portions 80 ana 84 a~d the auxiliary ankle member 86 of t~e prosthesi~ 10 is by a thermo~etting ~olding pro-cess including the utilization of molds having properly ~peA an~ sized ca~it~e~. m e ca~ities are designed to re-ceive the requi~ite num~er of laminates and the ~e~ ~ol-ume of polymer.
Unlike priox art unitary de~ice~, the f itting o~
the prosthe~is 10 in~olves the judic~ous aaiustment of the pxo~thesis by the prop~r combinat~on of for~foot and heel portions 80 and 84 and auxiliary anXle member 86, ~
tively. It al~o ~nvolve~ the selection of the properly de-signed ancil~ary pylon 30 which can be s~ e-1 by mean~ o~
the coupling gO to the a~tachment ~;ection g2 of the forefoot portion 80. only when the proper correl~t~on beL~en ~he forefoot portion 80, ~eel portion 84, auxiliary anXle member 8fi, and ancillary pylon 30 has been accomplished, can ~he ¢osmetic sh~oud, not shown, ~e instailed upon the assembled, Le~e~ e porti~ns of'the pr~sthe~is lo.
By the pro~thesis of ~y inven~io~ I provide a foot which can be carefully matched to the weight, ~tride and physical characteri~tics of the wearer. Thi~ is accom-plished by carefully bal~nci n~ the L~e -~ive physical char-~cteristics of the ~orefoo~ poxtion 80, the heel portion 84, '~ 2063504 the auxiliary ankle memker 86, an~ t~e various ~ections ~hereof.
Moreover, the a~embled prosthesis i8 ~ar lightex in weight than prior art pros~b~-e~ ~nce the inherent de-S ~ign and structure of the pros~h~ , the material~ u~ed andthe careful calculation of -~res~ factors o~ the ~om~vn~L~
of t~e pro~thesis permit fin~ L~ in7 of the prosthesis to the needs of the wearer t~e~eof.
The pros~he~is of my invention has been ~e~cribed with some particularity ~ut the specific design~ and con-struction~ disclo~ed are not to ~e ta~en as ~elimiting of t~e inven~ion in that ~ariou~ mo~ification~ w~ll at once ma~e themselves apparent to those of ordinary ~kill in the art, all of which will not depar~ fro~ ~he e~sence o~ the lS in~ention and all such chA~eo and modi~ications are in-tended to be encompA~s~A within the ~ o~R~ claims.
Backqround of the Invention:
This invention relates to foot prostheses in general, and speclflcally to a prosthetlc foot characterized by a unltary foot and heel constructlon, and/or an auxlliary ankle construction whlch permlts the flexlblllty of the prosthesls to be selectlvely determlned and easily changed. The inventlon also includes an improved coupllng for attachlng sald foot prosthesls to an auxiliary pylon tube.
The prior art is replete with various types of mechanical devices purporting to solve the foot prosthesis problem. Typical of early devices is U.S. Patent No. 2,075,583 issued June 30, 1937 naming Lange as lnventor, whlch incorporates a rubber form mounted ln operatlve relationshlp with a rigid metalllc core. Exemplary of the latest developments ln the fleld ls U.S. Patent No. 4,645,509 naming Poggl as inventor and issued February 24, 1987, whlch teaches a prosthetic foot incorporatlng a monollthlc keel or beam of relatlvely masslve proportions lntended to react to the load of an amputee's body durlng walking, running, iumping, and the like and to rel'ease the resultant stored energy to create foot lift and thrust complementlng the amputee's natural strlde.
., ~
- However, each of the prior art devices has significant deficiencies; specifically, the component parts of the prosthesis, as in Lange, are too heavy and too rigid or, as in Poggi, are too masslve and monolithic to respond properly to the nuances of stress-response gradients characteristic of the human foot.
One of the primary factors which has inhibited the creation of a truly successful prosthetic foot has been the fixation of the prior art with the duplication of the structural aspects of the skeletal and muscular components of an actual human foot. In many instances, as exemplified by Poggi '509, mentioned hereinabove, even the toes of the foot are attempted to be duplicated by providing simulacra thereof. It is this fixation upon the mechanical elements of the human foot which has restricted the art to an attempt to duplicate the human foot components, a tendency which is particularly exemplified in U.S.
Patent No. 3,335,428 issued August 15, 1967 naming Ga~dos as inventor.
My U.S. Pat. No. 5,037,444, issued August 6, 1991, 'discloses certain concepts relating to a prosthetic foot characterized by a forefoot portion and a heel portion which may be permanently or demountably associated with each other whereby both the forefoot portion and the heel portion can be readily exchanged with correspondingly constructed heel and forefoot portions. This exchangeability permlts size B
CA 02063~04 1998-03-0~
adjustment or accommodation of different spring rates to suit the size of foot of the amputee or the stride and weight of the amputee, yielding an almost infinite range of combinations of spring rate and size to the amputee, and allowing a natural stride and resilience of gait which has to been obtainable by prior art prosthetic devices. The invention of my U.S. Pat.
No. 5,307,444 utilizes a horizontal attachment surface for attaching the prosthesis to a pylon, however; this horizontal attachment surface imparts some limitations on size, weight and performance of the prosthesis, as well as in difficulty and expense of manufacture, which limitations are not present in the instant invention.
Summary of the Invention:
In one embodiment my invention provides a foot prothesis which is characterized by a fore-foot portion and a heel portion which may be permanently or demo~ntably associated with each other, with the forefoot portion having an upwardly extending attachment section providing ease of manufacture and resistance to rotation, whereby both the forefoot portion and the heel portion can be readily exchanged with correspondingly constructed forefoot and heel portions to provide size adjustment or accommodation of different spring rates to suite the size of foot of the amputee or the stride and weight of the amputee, and further adjustments can be made by the use of an auxiliary ankle spring member. Therefore, an almost infinite combination of spring rate and size can be provided CA 02063~04 1998-03-0~
to the amputee, achieving a natural stride and resilience of gait, which has not been obtainable by prior art prosthetic devices.
In another embodiment the invention provides a prosthetic foot of the aforementioned character having an interchangeable or permanent forefoot portion which has a toe section, an arch section, a curvilinear ankle section, and an upwardly extending attachment section, all constructed without the necessity of tapering of the thickness thereof. Also incorporated in the aforementioned foot is a heel portion which has an attachment section secured to the intersection of the arch and toe sections of the forefoot portion and a heel section extending beyond the curvilinear ankle and attachment sections of the forefoot portion. The heel section extends beyond the curvilinear ankle and attachment sections of the forefoot portion.
As previously indicated, the forefoot portion can be provided in different sizes and spring rates, and an auxiliary ankle member may be utilized, thus permitting the gait, weight, and activity level of the amputee to be readily accommodated. Correspondingly, the forefoot portion can be demountably associated with the heel portion of the foot to permit different sizes of heel portion having different spring rates to be mounted in operative relationship with the forefoot portion.
CA 02063~04 1998-03-0~
In another embodiment the invention provides a prosthetic foot of the aforementioned character in which both the forefoot and heel portions of the foot are fabricated, and the auxiliary ankle may be fabricated, from superimposed laminates maintained in operative relationship by an encapsulating polymers, and further in which said toe, arch, ankle and attachment sections of said forefoot portion, said heel section of said heel portion, and said auxiliary ankle attachment are susceptible to bending stress determined by the number of the laminates and polymers in the respective toe, arch, ankle and attachment sections of said forefoot portion, in said heel section of said heel portion, and in said auxiliary ankle attachment. Thus, the various portions and sections thereof are encapsulated in a polymer and capable of spring stress response as ankle loads are imposed thereupon during the utilization of said foot.
In another embodiment the invention provides a prosthetic foot of the aforementioned character, having a forefoot portion which consists of continuous, integrally and simultaneously formed toe, arch, ankle and attachment sections, said sections being fabricated as a unitary structure by polymer impregnation of superimposed reinforcing laminae maintained in the desired configuration of said forefoot portion and said toe, arch ankle and attachment sections being capable of spring stress generated energy storage whereby the subjection of the toe sections to bending moments will cause uniform transmission of spring stress CA 02063~04 1998-03-0~
through said arch section and through said curvilinear ankle section of said forefoot portion to said attachment section thereof.
Alternatively, chopped fiber or other suitable reinforcing material may be utilized instead of or in addition to the aforementioned laminates.
In another embodiment the invention provides a prosthetic foot in which the curvilinear ankle section of said forefoot portion has its upper extremity constituted by said upper attachment section and its lower extremity extending into and constituting said arch section, said lower extremity, said curvilinear ankle section and said upper attachment section maintaining an approximately uniform thickness transversely of the longitudinal axis of said sections. Similarly, said heel portion and its various sections are provided with an approximately uniform thickness transversely of the longitudinal axis of said sections.
In another embodiment the invention provides an auxiliary ankle attachment, which is associated with the ankle section of said forefoot portion to increase the resistance of said ankle section to loads imposed upon the toe section of said forefoot portion. The concept of the auxiliary ankle involves the provision of ankle members characterized by different spring rates, which permits the resistance of the ankle section to deflection to be precisely adjusted to the weight, CA 02063~04 1998-03-0~
activity level and other characteristics of the individual for whom said foot is being adjusted.
The polymers utilized to encapsulate the fibrous laminae are characterized by elastlcity and flexibility so that the forefoot and heel portions deflect proportionally to the engagement of said forefoot portion with an adjacent surface, causing the resultant energy to be stored and subsequently released when the gait of the amputee incorporating thrust and lift components results in the utilization of the stored energy and a consequent reduction of the energy expended by the amputee. There is a gradual increase in stiffness as the lever arm of the toe section of the forefoot portion shortens due to gradual deflection thereof.
In another embodiment my invention provides an improved coupling mechanism for attaching a prosthetic foot of the above mentioned character to an auxiliary pylon tube which is in turn attached to the wearer's leg.
In order to impart a cosmetic aspect to the prosthetic foot, after proper fitting of the foot to insure that the forefoot and heel portions and the auxiliary ankle are properly balanced and of appropriate size, the prosthesis may be encapsulated in a suitably shaped foot-like shroud to facilitate the utilization of the prosthetic foot with a conventional shoe. The enclosure must be sufficiently flexible so as not to inhibit the free movement and flexure of CA 02063~04 1998-03-0~
. .
the forefoot and heel portions and the auxiliary ankle of the prosthetic foot, but, because of the inherently resilient and stress-absorbing characteristics of said foot, little dependence is needed upon the ancillary cushioning action of the enclosure.
In another embodiment my invention provides a prosthetic foot characterized by extreme light weight, instantaneous response to imposed loads and correspondingly instantaneous delivery of stored energy when the gait of the wearer indicates that such stored energy is to be released.
Moreover, the foot may be readily mounted in operative relationship with conventional ancillary pylons and couplings, and can be fine-15= ~
~=
~tuned by the blending of the forefoot and heel portions andauxiliary ankle characteristics to achieve the ultimate ln operatlve response to the needs of the wearer.
Consequently, the wearer of the foot may engage in a wlde variety of actlvities which were precluded ln the past because of the structural llmltatlons and correspondlng performances of prior art prostheses. Running, ~umping and other activities are sustained by the foot and it amy be utilized ln the same manner as the normal foot of the wearer.
In accordance with one aspect of the lnvention, there is provided a foot prosthesis adapted to be demountably secured to a vertlcally orlented rlgld pylon member for provldlng kinematlc support to an amputee relative to the ground, comprlslng:
a forefoot member detachably secured to and extendlng relatively downward and forward from the rigld pylon member. The forefoot member is formed of a resillent and flexlble material and ls adapted to store and release energy by bending ln response to a downward compressive force exerted by the amputee. The forefoot member foot comprlses:
a substantlally vertically oriented upper attachment sectlon adapted to detachably secure sald forefoot member to the rlgid pylon member;
a relatively stiff ankle section capable of resisting excessive bendlng of the forefoot member, the ankle section ls configured to bend in a manner analogous to the manner in which ~-a normal human foot pivots about a normal ankle ioint;
a relatively compliant toesection extending relatlvely forward from the ankle section defining a forward lever arm of said foot prosthesis; and a heel member detachably secured to and extending relatively downward and rearward from said forefoot member defining a rearward lever arm of sald foot prosthesis.
The forefoot member can be readily detached from the rigid pylon member and is interchangeable with like forefoot members having different resiliency characteristics such that a wide range of varying actlvity levels may be sustained ln a single foot prostheses.
In accordance with another aspect of the present invention, there is provided a lower limb prosthesis adaptable to a socket fitted to the stump of a lower-limb amputee for providing resilient kinematic support to said amputee during normal walking, running and ~umping activities, comprising:
a substantially rigid tubular pylon member having a proximal end adapted to engage said socket and a distal end extending substantially vertically and termlnating at about the location of said amputee's normal ankle ~oint, said distal end having front and rear sides; and a detachable flexible foot prosthesis comprising a spring-like foot member adapted to be selectively attached to said distal end of said tubular pylon member according to a particular desired activity or a particular desired degree of kinematic resilience, said foot member further comprising:
9a _ an upper attachment sectlon havlng a substantlally vertlcal mountlng surface adapted to closely recelve a correspondlng substantially vertlcal mountlng surface dlsposed on said rear side of said distal end of said tubular pylon member;
an intermediate ankle section formed integrally wlth and curving substantially continuously downward and forward from said upper attachment section such that bending stress is distributed substantially evenly therethroughout;
a toe section having a proximal end and a distal end, said proxlmal end being formed integrally with said intermediate ankle section and said distal end extending forwardly to correspond to the toe of the user, said toe section curving substantially continuously forward from said proximal end to said distal end thereof such that bending stress is distributed substantially evenly therethroughout, said toe section meeting the ground at a point near said distal end of sald toe section to define, together with said ankle section, a forward lever arm for said foot member for returning substantial energy to said ~0 user during toe off; and a heel member extending substantially contlnuously rearward and downward from a polnt tangentlal to sald lntermedlate ankle sectlon such that bendlng stress is distrlbuted substantlally evenly throughout sald heel member, sald heel member providing a rearward lever arm for said foot member;
sald heel member and said toe section providing substantially the sole support for loads incurred by sald flexlble foot prosthesls 9b -durlng heel strike and toe off, respectlvely;
whereby said foot member can be readily detached from said tubular pylon member and is interchangeable with like feet members having different resiliency characteristics without having to change or adiust sald socket or the length of said tubular pylon member, such that a wide range of varylng actlvlty levels may be sustained in a slngle prosthetic device.
In accordance with yet a further aspect of the present invention, there is provlded a lower limb prosthesis adaptable to a socket fitted to the stump of a lower-limb amputee for providing reslllent kinematic support to sald amputee durlng normal walklng, running and ~umping actlvltles, comprlslng:
a substantlally rlgld tubular pylon member having a proximal end adapted to engage said socket and a dlstal end extendlng substantially vertically downward and terminatlng at about the locatlon of sald amputee's normal ankle ~olnt; and a detachable flexlble foot prosthesls comprlslng a sprlng-llke foot member adapted to be selectively attached to sald dlstal end of said tubular pylon member according to a particular desired activity or a particular desired degree of kinematic resilience, said foot member further comprising:
an upper attachment section having a substantially vertically oriented attachment surface adapted to attach sald ~5 foot member to sald tubular pylon member;
an lntermedlate ankle sectlon formed lntegrally wlth and curvlng substantially continuously downward and forward from said upper attachment section such that bending stress is i ,~, CA 02063~04 1998-03-0~
distributed substantially evenly therethroughout, said intermediate ankle section providing substantially the sole support for all vertical, transverse and torsional loads transmitted through said tubular pylon member to said flexible foot prothesis;
a resilient toe section formed integrally with said intermediate ankle section and curving substantially continuously forward therefrom such that bending stress is distributed substantially evenly therethroughout, said toe section defining a forward lever arm for providing substantially the sole support for all vertical, transverse and torsional loads transmitted through said flexible foot prosthesis during toe off; and ~5 a resilient heel member extending substantially continuously rearwardly from said intermediate ankle section such that bending stress is distributed substantially evenly throughout said heel member, said heel member defining a rear lever arm for providing substantially the sole support for all vertical, transverse and torsional loads transmitted through said flexible foot prosthesis during heel strike;
whereby said foot member can be readily detached from said tubular pylon member and is interchangeable with like feet members having different resiliency characteristics without having to change or adjust said socket or the length of said tubular pylon member, such that a wide range of 9d CA 02063~04 1998-03-0~
varying activity levels may be sustained in a single prosthetic device.
Other embodiments and modifications of the invention will be apparent from the following specification and the accompanying drawings, which are for the purpose of illustration only.
Brief Descri~tion of the Drawinqs:
FIG. 1 is a side elevation view of portion of a prosthesis constructed in accordance with the teachings of the invention;
FIG. 2 is a partially sectional plan view, taken along line 2-2 of FIG. 1;
FIG. 3 is a front elevation view, taken along line 3-3 of FIG. 2; and qe 2063~04 FIG. 4 i~ a partially sectional side ele~ation ~iew, taken along l~ne 4-4 of ~IG. 2.
Pescri~t;on o~ Pr~ferred F~?di~
Referring to t~e dxawin~c, and particularly to FI~S. 1 and 2 thereof, ~ ~how a foot prosthe8i~ lO con-~tructed in accoraance with the toAc~gs of the invention and including a forefoot portion ~0 an~ a ~eel portion 84 operatively and demountably connectea to each other by bolt an~ nut combinations 104 associated wit~ load-~ransmitting metallic plates lO~. If indicated, the forefoot and heel portions can be permanentl~ Se_~L~ to each other, as by epoxy adhesive or the like.
The for~oot portion 80 of the pro ~hesis lO in-clude~ a substanti~l~y rigid upper a~tachment ~ection 92 r a cur~ilinear a~kle sRction 94, ~n arch ~ection 96 and a toe section 82. The sections 92, 94, 96 and 82 of the ankle portion 8~ are preferably formed integrally with one another and simultaneously by 5he incorporation of a plurality of laminae embedded ~n a hardened, flexible polymer. Altern~-tively, chopped fiber or other suitable reinfor~ing materialmay be ~t~l~zed instead of or in addition to the afore~en-tion~d laminae.
,.
The attachment ~ection 92 inçoL~o~ates two cen-trally-lo~ated openings 88, FIG. 4. The attachment se~tion 92 i~ ~ubstantially rigid and capable of sust~ining tor-sional, imp~ct and other loads i~pressed thereupon by t~e an~le portion 80 and heel portion 84 of the pro~thesis. In additio~, the inherent rigidity of the attachment section 92 cause~ t~e e~fecti~e transm~sion of the aforesaid load~ ~m-posed theLeupG~I to a ~uita~le ancillary prost~etic py~on 30, by bolt and nut com~inations 98 assembled thr~ugh openings 88 ~o a pylon coupling 9~. A s~rew loo or other suita~le attachment means Be~ S the anc~l~ary pylon 30 in the cou-pling 90.
In the partlcular embodiment o~ ~IGS. 1-4, the auxili~ry ankle 86 is mounted b~tw~en the coupl1ng 90 and 1~ ankle por~ion 80, and ~s ~ec~L~d in operative relat~onship with the ankle portion ankle se~tion 94 through the use o~
centrally-loçated or6~n7~ in an atta~hment section 1~2 o~
the ankle member 86, wh~ch o~o~;n~c are substantially aligned with o~in~s 88 of t~e ankle portion attach~ent section 92. Bo~t ~na nut combinations 98 retain the variou~
com~G,.2nts in the aforecaid operati~e relationship. Al~er-nati~e ~h~mentS would in~lu~e securing the aux~liary an-kle 86 to a rearwa~d ~urface o~ the attachment section ~2.
In the preferred e~bodi~ent, bolt and n~7t combina-tions 104, in conj~nction with the load-~istributing metal-1ic plate~ 106, serve to sec~re the heel port~on 84 in oper-ative re~ationchip with ths forefoot portion 80 of the pros-t~esis. Thi~ mode o~ affixation facil~tates the assembly ordismounting of ~elected heel portions 84 in operati~e rela-tionship with selected foxe~oot portions 80, thus per~itting a wide range of differen~ ~izes and stress load r~on~e characteristics to be r~lated to each other to accomplish the optim~m functional co~l~O~,or~nce between the forefoot and heel portions ~0 a~d 84.
An auxil~ary an~le me~ber 86 can be util;z~d to decrease ~he flexibility of the ~ore~oot heel porti~n 80.
The ~Y~ ry ankle 86 i~ form~d fro~ fibrous la~inate~ of the 6ame c~arac~er as the ~arious portionf of ~he pro~the~;is 10. In the prefsrred s~bodimsnt, the auxiliary ankle 86 in-c~,~oYate~ an atta~hment ~ection 102 which is operat~vely associated wi~h the couplin~ 90 and the upper attachment ~ection 92 of t~e forefoo~ portion 80, and pre~erably there-20 beL~raes~. The auxiliary an~le 86 is preferably S~L~ inoperative relatiQ~ r with ~he curvilinear ankle se~tion 94 of forefoot portion 80 through the aforementionQd assembly of the coupling 90 with the bol~ and nu~ combinations 98.
On its end opposite ~rom the attachment section ~2, ankle member 8~ ~as a tapered section 1~8 which provide~ a varying flexibility along the length of the ankle member 86 and al~o lessen~ the likelihood that the a~kle member 86 will be un-desirably ~nagged or restrained in it~ cooperat~e rela-s tionship with ~orefoot ~oxtion 80 and the cos~etic cover o~
the prosthesi~, ~ore thG~ vuy~ di~cu~e~ beloW. In alter-native e~bodiments, as will be understood by tho~e skilled in tne art, ~uch tape~ing is not required i~ order to prac-~ice the invention, and accor~in~ly, the ankle member 86 can be provided with a xelat~ely uniform thio~ along the length thereof.
In the preferred e~odi~ent, the auxiliary ankle ~e~er 86 is se~e~ against the ~elatively internal radius of the curvilinear an~le section 94, so that t~e anticipated u~war~ deflection of a toe section ~2 of the for~foot por-tion 80, as more t~oroughly described be~ow, will ev~ ually cause de~ormation o~ t~e auxiliary anXle 86 as well as de-formation of t~e an~le section 94, e~fectively combining the deformation resistance and el,~.yy s~orage ch~racteri~tics of the auxiliary an~le ~em~er 86 with tho~e of the ankle sec-tion 94. Alte~native em~od~ment~ would includQ securing the auxi~iary ankle 86 ~o the rearward surface of the attachment ~ection 92 and further securing the auxiliary ankle apered section 108 to an under 6urfac~ 62 of the anXle ~ection 9~
206~04 in order to achieve the aforedescribed desirsd com~ination of the deformation resistance and energy ~torage character-istics of the auxil~ary ankle me~ber 86 with tho~e of the ankle section 94.
The auxilia~y ankle ~ember 86 can be pro~ide~ wit~
different number6 of laminates to ma~e it ~ore or les~ co~-pliant to loads ~ransmitted throug~ the ankle ~ec~ion ~4.
Con~equently, w~en con~ronted with various anomalies in an amputee, such as over~eight or exc~ss ac~ivity levels, the ba~ic structure of tne forefoot portion 80, and mo~e partic-ular~y the ankle section 94, can be materiall~ modi~ ed to proYide ankle portion action wh~c~ is precisely ad~u~ted to the needs of the amputee. Moreover, a variety of auxiliary an~le membexs B6 can be mad~ ~ailable to an ampuSee, allow-ing the flexibility of the prosthesi~ to be ~djusted on the ~asi~ of the particular activity which the ~mput~e i6 under-taking~
As previou~ly ment~oned, a cosmetic cover, not shown, can be pro~ided to ~hroud the prosthe~i~ 10 a~ter t~e optimum assemblage of the forefoo~ and heel portions 80 and 84 and any ~xiliary ankle member 86 has ~een acco~pli~ed.
Unlike prior art construction~, hc~ , the cosmetic cover, which may be formed of low-density formed polymer, i5 not regu~red to ser~e any anc~llary shoc~-absorbing or other stre~s-isolating f~nction since all of ~he loads im~G~6A
upon the prosthesi~ ~an be a~sorbed, transmitted and re-as~erted in a manner to be descri~ed in grQater detail be-low.
The bolt and nut combination~ 104, in conjunction with ~he load-di~ri~uting metallic p~ate~ ~06, ser~e to se-cure the heel portion 84 in operat~ve relation~p with the forefoot portion 80 of the prosthesis.10, a~ b~st shown in FIGS. 1-2 of t~e drawings. The aforesaid mode of affixation facilitate~ the ~ssembly or dismounting of ~elected heel portions 84 in operativ~ ~elationship with selected forefoot portion~ 80 of t~e pros~hesis 10, thu~ permitting a wide range of di~ferent eizes and stre~s load response char-acteristics to ~e ~elated to each otber t~ accompl~sh the optimu~ functional cG L~on~le~ce ~etween the forefoot a~d heel p~rtions 80 ana 84 to ac~ommodate to the m~ximum extent the needs of ~he wearer of the prosthesis, and, al~o, to pro~ide for a proper mating of the prosth~sis 10 with 8 ~e-lected, ancillary py~on 3~ or the like.
The ~orefoot portion 80, as ~est ~own in ~IG. 1 of t~e drawings, includes a toe Qection 82, an arch sectioh g6, a curvilinear ankle section 94, and an a~tac~ment sec-tion 9~. T~e heel portion 84 in~lude~ an attachment se~tion 22 and a heel sec~on 28 which preferably has its rearwaxd 206350~
extre~i~y 56 ext~n~ing beyond an ~xtreme rQarward ~urf~ce 58 of ~e forefoot portion attachmen~ section 92 of the pros-thecis 10. Mating ~ores, not shown, in the arch section 96 of ~e forefoot por~ion 80 and the heel portion 84 ~eceive the re~pective bolt and nut combinations 104 to pro~i~e ~or t~e aforesaid facility in a~embling and ~ rcmbling of the forefoot and heel portions 80 and 84. In the p~efe~red emb~diment, the various ~ection~ of the forefoot port~on 80 are all constructed withou~ the necessity of tapering ~f the thickne~s thereof, alt~ough tho8e skill~d in the art will understand th~t the invention ~ not limited to such non-ta-pering ~n~uction.
Interpo~ed between ~he under surfa~ 62 of the an-~le sec~ion 94 of the heel por~on 8~ and an upper sur~ace 64 of the heel section 28 is a resilient, spring action function ~lock 70 of wed~ ape~ configuration to ~etermine the le~er arm of t~e heel ~ection 28 and ~olate the under surface 62 of t~e anXle section 94 and ~he U~L surface 64 of the heel section 28 fro~ each other. T~e fun~tion block 70 may ~e fabricated fro~ a wide ~a~iety of r~silien~ mate-rials, including natural and synthetic ~bbers or ~e like.
The materi~ls ~rom wh~ch the ~orefoot portion 80 ~nd heel portion 84 and the auxiliary anXle 86 are fabri-ca~ed ~us~ ~e such ~s to pro~ide an energy-storing, re-206350~
silient, spring-lik~ effect. ~hi# ic nece~sary because each engagement of the prosthecis 10 with an adjacent ~urface im-precse~ compression, torsional and ot~er loads upon the pro~thesis 10 which m~st be stored within ~e prosthe~is and then, dependent upon ~he stride o~ the ~earer, ~e reim-pressed upon said surface to achie~e a natural stride con-foxming, ideally, în all re~ s to t~e stride of the unim-paired l~mb o~ ~he w~arer of the ~rost~e~is 10.
~e forefoot and hee~ portions 80 and 84 and the a~xiliary ankle 86 of ~he prosthesis are pre$erab1y molded ~-~ unitary co~ponents and are carefully formed to prov~de for uniform absorption of stress imposed the~u~ . m e configuxat~on of both portlons 80 and 84 i~ o~ utmost impor-tance and the ~l.o~d f~ers, laminates, or other reinforc-lS ing material~, and the poly~er or polymer~ from whi~h theport~ons 80 and 84 are fabricated ~u~t be resil~ent and ca-pa~le of absorbing the compre~sive, torsional and other etre~ses referred to herei~hove and of rest~ring the stored energy created by such s~e~es, in a na~ral ~anner, to the impacted surface w~ic~ orlginally imro~e~ ~u~h ~tres~es upon the pros~hesis 10.
It has been found that there ~ a lim~ted number of polymers capabl~ of s~st~ini~ the significan~ stresses and repetitive loads impose~ upon the prosthes~s 10, partic-'~ 206350a~
ularly in the l~ght of the countless number~ of ~y~les to which the pro~thesi~ 10 is subjected ~uring normal, everyday use .
At present, the best materials for the pro~thesi~
are a composite o~ high-~trength graphite fiber in a hig~-toll7h~C epoxy ther~o6ettin~ resin system. ~here are sev-eral reasons for this: t~ high str~ngth; t2~ gtiffness to weight rat~o o~ graphite as compared to oth~r ~at~rial~; t3) the almost comple~e return of input or stored energy: (4) ligh~ weight; ~5) high fatigue s~rength; and ~) minimal creep. As an alternative material, fiberglassfepoxy is a fair choice, but it is not ~s good as graphite because of lower fatigue st~ength and highe~ den~ity. ~evlar i~ e~en le~s acceptable due to poor compression and shear strength, althou~h it is the lowe~t density of those mentioned~
An i~portant ~spect of t~e polymers and chopped fibers or lami~ates referred to ~ereinabov~ i~ tha~ they are characterized by n~e~o~, but not eY~-r_ci~e, flexural deflec-tion under lo~d, which'characteri~tic permits the ~hoc~-ab-sorption stress lo~ng o~ the pros~he~is 10 while ~R~ntain-ing sufficien~ sta~ility to ~vcn~ the collap~e o~ the forefoot ana heel portions 80 and 84 and She ankle member 8 of the prosthesis 10 while loads are imposed t~ere~.,.
To achie~e the relatively thin ~o~ ruction of the foot and ankle portions 80 and ~4 and the auxiliary ankle me~er 86 of the pro~;thesi~ 10, the afore~aid polymers are utilized in c~njunction with va~ous reinforclng or laminat-ing materialc. Variou~ types o~ fibrous laminae can be uti-lized to achieve the contin~um requ~red by the design of the foot and ankle portions 80 and 84 and the ankle member 86 to ~omplement the stress-ab~or~ing and storing c~aracteri~tics ~f the polymers in which said fibrous lam~nae are em~ A~.
0~ course, t~ere ~s a wide ~ariety of f~brous re-infor~ements in the form of laminae available at the ~l~_cnt ~ime, including such inorganic ~ibers a~ gla~s or carbon fiber~. ~hese inorganic fib~rs are cus~omar~ly pro~ided in tape or s~eet form and can be readily ~uperi~posed in the mold to penmi~ the~ ~o be encapsulated in the selected poly-mer~ As set forth above, the fibers may ~lso be chopped or in ot~er form.
O~iously, the number of superlmposed laminae or other reinforcing laminae ~nd ~hQ lengths thereof, togeeher with the thickness of the en~psulating polymer, deter~ine the stress characteristics of the resultant foot and ankle portions 80 and 84 and the an~le member 86 and, co~Le~ d-ingly, determine the total weig~t o~ She prosthes~s 10. As w~ e apparent ~rom the di~c~lr~ion hereinbeloW, the indi-20635Q~
vidual foot and anXle portions 80 and 84 and an~le member g~
are de~igned to specifically aCCOmmodate individuals having different foot cizes, different weights and different strides and the indi~id~al design of the f~ot and an~le por-tions 80 and 84 and the ankle member 86 pro~ides for matc~-ing, to an extent previou~ly unknown in the art, the natural chara~teri~tics of t~e ~earer'~ uninjured limb.
~urthermore, the function block 70 can be provided in different sizes and in material~ having different ccm-pre~sion character~gtics ~o tha~ the lever ar~ and the cor-r~ ndi~ deflection~ of the heel section 2~ may ~e in-cre~s*d or decrea6ed.
As previously mentioned, the ankls ~ection 94 is formed integrally with the ~pper ~ttachment ~ection 18 and said attachmen~ ~ection constitutes the upper ex~remity of the ankle ~ection ~4, while the ~ nitiat~on of the arch sec-tion 96 of the forefoot portion 80 oonstitutes the lower ex-trem~t~ of the an~le 6ection 94. The configuration of the ankle ~ection 94, in con3unction ~ith the auxiliary ankle ~o member 86, i~ the means whereLy comprQssive lo~ds im~
during impinge~ent of the foot and ankle por~ions 80 and 84 ~pon an adjacent surfaoe are a~~G~L~d and subsequently reim-po~ed upon said ~urface. The an~le portion 94 and the aux-ilia~y ankle member 86 are ~o designed that they Punction, 206350~
s~bstantially, as an an~le joint to permit pi~oting of the forefoot portion 80 thereabout in a manner analogous to the manner in ~hich ~he normal foot pi~o~s about the normal an-~le joint about an axi~ transversely of sAid ankle jotnt.
The radii of curvature of the ankle section 94 and any auxiliary ankle member 86 correspon~ to provide ~or ~he inherent re~liance and deflection of the ~orefoot portion 80 while inhib~ting un~e~ired, excessi~e collap~e of the ~n-kle section 94.
It will ke noted that the attachment ~ection 22 of ~he heel portion 84 i~ substantia~ly rigid and that the ini-t~a~ de~lection of the heel gection 28 v~ c i~mediately adjacen~ t~e rearward extrem~ty 56 of ~aid h~el ~ection, terminating immeaiately adjacent the ~unction block 70. Ob-~iously, a greater length or le~ resilient function block 70 reduces the lever ar~ of the heel seo~ion 28 of the hPel porti~n 84 and co~e~ y re~uces the ~odulu~ of de-fl~ction of caid ankle section, while a smaller l~ngth or more re~ilient function bloc~ 70 incr~ases the lever arm and correspond~ngly inrreases the de~lection of ~e ~eel sectio~
28 under load.
The toe section 82 and heel ~ection ~8 can be pro-~ided In different leng~hs to corr~o,.~ to the size of the foot of the wearer of the prosthesi-~ 10. When ~uch differ-20635~4 ent lengths are pro~ided, corre~.r~dj ng reduction or ~n-crease in the number of la~inae and thic~-eFc of taper o~
the resp2ctive toe section 82 and heel section 28 can be made to provide for t~e proper flexure of said toe and heel section~. It should also ke noted that, e~en with th~
shortest heel section 28, the re~rward ~x~mity 56 thereof preferably projects ~_y~l~ the rearward 6urface 58 of the ~refoo~ portion 80. Co~,~eyu~ ly, ~he stabllizing and ~ ab80rption chara~terist~c~ of the heel section 28 of the prosthe~is lo are always mainta~ned.
Those skilled in the ar~ will understand that many alternative embodiments of the coupling 90 can be con-s~ructed and practiced ~nterc~angeably in oPnnQct~on ~ith the many alte~nati~e embodiment~ of the rest o~ the inven-1~ t~on.
It will, of course, be o~ious to those skilled i~~Ae art that, with re~p~ct ~o any smbodim~nt of th~ ~nven-tion, the ~ibrous reinforcements in ~he form of laminae plies e~ sul~ted ~n the prosthesis may be fayed-o~ tapere~
to acco~plis~ a gra~u~l tran~i~i~n as the number o~ p3ie8 ~S
~e~ in any ~rea o~ the fore~o4~ or heel port~on~
210~e6~eL, if a relati~ely lightweigh~ indi~idual partakes in sports o~ other ac~ ies which ~ub~oc~ the prosthesis 10 to grea~e~ loads, a ~eel or for~foot poxtion . .
., .; .
~
84 or 80 will be ~it~ed which will accommodate for tho3e greater loads.
The an~le ~ection g4 o~ the forefoot portion 80 deflects under load and the auxiliary ankle member 86 si~i-S larly deflect~. Additionally, the toe and arc~ ~ections 82 and 96 of the forefoo~ portion 80, and the heel section 28 of the heel portion 84, de~1ect under ~uch loa~. Therefore, when ~ubjected to vertical compression lo~ds, the ankle sec-tion 94, the auxiliary an~le membex 86, the arc~ sec~ion 96, and the toe and heel sections 82 and 28 absorb such load~.
Consequently, there is no ~tress concentration, e~ther ~n ~he impa~t pha~e when the adj~en~ ~urface is ini-tiall~ contacte~ ~y the wearer of the prosthesis ~0, or when return o~ the a~cumula~ed forces ~tored in the prosthesis 10 is acco~plished.
~he cur~ature of the toe section 82 provide~ fo~
maximum accommodation of said sectio~ during ~ur~ace contact in both the impac~ and del~very ph~se5 of the prosthesi~ 10.
Similar con~iderations apply ~o the curvature o~ th~ heel ~ection 28 of the heel portion 84 of the prosthesis 10. It will be noted tha~ the curva~ures of the toe and heel sec-tionc 82 and 28 pro~ide for rela~vely extended levRr arm~
Which achie~e stability and, a}~o, stres~ ~torage and stres~
reaction.
206350~
The prefer~ed ~ethod of ~anu~acturing t~e ~orefoot and ~eel portions 80 ana 84 a~d the auxiliary ankle member 86 of t~e prosthesi~ 10 is by a thermo~etting ~olding pro-cess including the utilization of molds having properly ~peA an~ sized ca~it~e~. m e ca~ities are designed to re-ceive the requi~ite num~er of laminates and the ~e~ ~ol-ume of polymer.
Unlike priox art unitary de~ice~, the f itting o~
the prosthe~is 10 in~olves the judic~ous aaiustment of the pxo~thesis by the prop~r combinat~on of for~foot and heel portions 80 and 84 and auxiliary anXle member 86, ~
tively. It al~o ~nvolve~ the selection of the properly de-signed ancil~ary pylon 30 which can be s~ e-1 by mean~ o~
the coupling gO to the a~tachment ~;ection g2 of the forefoot portion 80. only when the proper correl~t~on beL~en ~he forefoot portion 80, ~eel portion 84, auxiliary anXle member 8fi, and ancillary pylon 30 has been accomplished, can ~he ¢osmetic sh~oud, not shown, ~e instailed upon the assembled, Le~e~ e porti~ns of'the pr~sthe~is lo.
By the pro~thesis of ~y inven~io~ I provide a foot which can be carefully matched to the weight, ~tride and physical characteri~tics of the wearer. Thi~ is accom-plished by carefully bal~nci n~ the L~e -~ive physical char-~cteristics of the ~orefoo~ poxtion 80, the heel portion 84, '~ 2063504 the auxiliary ankle memker 86, an~ t~e various ~ections ~hereof.
Moreover, the a~embled prosthesis i8 ~ar lightex in weight than prior art pros~b~-e~ ~nce the inherent de-S ~ign and structure of the pros~h~ , the material~ u~ed andthe careful calculation of -~res~ factors o~ the ~om~vn~L~
of t~e pro~thesis permit fin~ L~ in7 of the prosthesis to the needs of the wearer t~e~eof.
The pros~he~is of my invention has been ~e~cribed with some particularity ~ut the specific design~ and con-struction~ disclo~ed are not to ~e ta~en as ~elimiting of t~e inven~ion in that ~ariou~ mo~ification~ w~ll at once ma~e themselves apparent to those of ordinary ~kill in the art, all of which will not depar~ fro~ ~he e~sence o~ the lS in~ention and all such chA~eo and modi~ications are in-tended to be encompA~s~A within the ~ o~R~ claims.
2$
Claims (36)
1. A foot prosthesis adapted to be demountably secured to a vertically oriented rigid pylon member for providing kinematic support to an amputee relative to the ground, comprising:
a forefoot member detachably secured to and extending relatively downward and forward from said rigid pylon member said forefoot member being formed of a resilient and flexible material and being adapted to store and release energy by bending in response to a downward compressive force exerted by said amputee, said forefoot member foot comprising:
a substantially vertically oriented upper attachment section adapted to detachably secure said forefoot member to said rigid pylon member;
a relatively stiff ankle section capable of resisting excessive bending of said forefoot member, said ankle section being configured to bend in a manner analogous to the manner in which a normal human foot pivots about a normal ankle joint; and a relatively compliant toe section extending relatively forward from said ankle section defining a forward lever arm of said foot prosthesis; and a heel member detachably secured to and extending relatively downward and rearward from said forefoot member defining a rearward lever arm of said foot prosthesis;
whereby said forefoot member can be readily detached from said rigid pylon member and is interchangeable with like forefoot members having different resiliency characteristics such that a wide range of varying activity levels may be sustained in a single foot prostheses.
a forefoot member detachably secured to and extending relatively downward and forward from said rigid pylon member said forefoot member being formed of a resilient and flexible material and being adapted to store and release energy by bending in response to a downward compressive force exerted by said amputee, said forefoot member foot comprising:
a substantially vertically oriented upper attachment section adapted to detachably secure said forefoot member to said rigid pylon member;
a relatively stiff ankle section capable of resisting excessive bending of said forefoot member, said ankle section being configured to bend in a manner analogous to the manner in which a normal human foot pivots about a normal ankle joint; and a relatively compliant toe section extending relatively forward from said ankle section defining a forward lever arm of said foot prosthesis; and a heel member detachably secured to and extending relatively downward and rearward from said forefoot member defining a rearward lever arm of said foot prosthesis;
whereby said forefoot member can be readily detached from said rigid pylon member and is interchangeable with like forefoot members having different resiliency characteristics such that a wide range of varying activity levels may be sustained in a single foot prostheses.
2. The foot prosthesis of claim 1, further including an auxiliary member associated with said ankle section to resist the excessive upward bending of said ankle section and to provide additional energy storage and release characteristics to said foot prosthesis.
3. The foot prosthesis of claim 1, wherein said forefoot member is demountably secured to said pylon member by one or more nut and bolt members permitting said amputee to utilize various sizes of forefoot members having various energy storage characteristics
4. The foot prosthesis of claim 1, wherein said ankle section and sald toe section are integrally formed to form said forefoot member, wherein said heel member is secured to the underside of sald forefoot member.
5. The foot prosthesis of claim 4, wherein said forefoot member has an underside and said heel member has a top side, wherein a resilient member is positioned adjacent said underside of said forefoot member and said top side of said heel member to determlne the lever arm of said heel member.
6. The foot prosthesis of claim 4, wherein said heel member is demountably and/or adjustably secured to said forefoot member by one or more nut and bolt members.
7 . The foot prosthesis of claim 6, wherein one or more plates are provided to distribute the stress concentrations imposed by said one or more nut and bolt members acting on said sections of said forefoot member and said heel member.
8. The foot prosthesis of claim 1, wherein an attachment device is positioned adjacent said pylon member and said forefoot member to secure said forefoot member to said pylon member.
9. The foot prosthesis of claim 1, wherein one or more nut and bolt members are provided to secure said forefoot member to said pylon member.
10. The foot prosthesis of claim 8, wherein said attachment device has a bracket to secure said forefoot member to said pylon member.
11. The foot prosthesis of claim 2, wherein said ankle section is curved and said auxiliary member extends along the internal radius of said ankle section.
12. The foot prosthesis of claim 2, wherein said auxiliary member is tapered to provide varied resistance to excessive bending of said ankle section.
13. The foot prosthesis of claim 2, wherein said ankle section and/or said auxiliary member is comprised of superimposed laminates maintained in operative relationship by an encapsulating polymer.
14. The foot prosthesis of claim 2, wherein said ankle section is curved and said auxiliary member has substantially the same radius of curvature as said ankle section.
15. The foot prosthesis of claim 2, wherein said auxiliary member is demountably secured between said pylon member and said forefoot member, wherein said auxiliary member extends downward and forward therefrom.
16. The foot prosthesis of claim 2, wherein said auxiliary member is positioned adjacent said ankle section to resist the upward bending of said ankle section and the upward deflection of said ankle section causes an immediate and equal upward deflection of said auxiliary member.
17. The foot prosthesis of claim 2, wherein said auxiliary member is demountably associated with said ankle section such that the flexibility characteristics of said ankle section can be adjusted by utilizing auxiliary members having different thicknesses and flexing characteristics.
18. The foot prosthesis of claim 1, wherein said pylon member is tubular.
19. A lower limb prosthesis adaptable to a socket fitted to the stump of a lower-limb amputee for providing resilient kinematic support to said amputee during normal walking, running and jumping activities, comprising:
a substantially rigid tubular pylon member having a proximal end adapted to engage said socket and a distal end extending substantially vertically and terminating at about the location of said amputee's normal ankle joint, said distal end having front and rear sides; and a detachable flexible foot prosthesis comprising a spring-like foot member adapted to be selectively attached to said distal end of said tubular pylon member according to a particular desired activity or a particular desired degree of kinematic resilience, said foot member further comprising:
an upper attachment section having a substantially vertical mounting surface adapted to closely receive a corresponding substantially vertical mounting surface disposed on said rear side of said distal end of said tubular pylon member;
an intermediate ankle section formed integrally with and curving substantially continuously downward and forward from said upper attachment section such that bending stress is distributed substantially evenly therethroughout;
a toe section having a proximal end and a distal end, said proximal end being formed integrally with said intermediate ankle section and said distal end extending forwardly to correspond to the toe of the user, said toe section curving substantially continuously forward from said proximal end to said distal end thereof such that bending stress is distributed substantially evenly therethroughout, said toe section meeting the ground at a point near said distal end of said toe section to define, together with said ankle section, a forward lever arm for said foot member for returning substantial energy to said user during toe off; and a heel member extending substantially continuously rearward and downward from a point tangential to said intermediate ankle section such that bending stress is distributed substantially evenly throughout said heel member, said heel member providing a rearward lever arm for said foot member;
said heel member and said toe section providing substantially the sole support for loads incurred by said flexible foot prosthesis during heel strike and toe off, respectively;
whereby said foot member can be readily detached from said tubular pylon member and is interchangeable with like feet members having different resiliency characteristics without having to change or adjust said socket or the length of said tubular pylon member, such that a wide range of varying activity levels may be sustained in a single prosthetic device.
a substantially rigid tubular pylon member having a proximal end adapted to engage said socket and a distal end extending substantially vertically and terminating at about the location of said amputee's normal ankle joint, said distal end having front and rear sides; and a detachable flexible foot prosthesis comprising a spring-like foot member adapted to be selectively attached to said distal end of said tubular pylon member according to a particular desired activity or a particular desired degree of kinematic resilience, said foot member further comprising:
an upper attachment section having a substantially vertical mounting surface adapted to closely receive a corresponding substantially vertical mounting surface disposed on said rear side of said distal end of said tubular pylon member;
an intermediate ankle section formed integrally with and curving substantially continuously downward and forward from said upper attachment section such that bending stress is distributed substantially evenly therethroughout;
a toe section having a proximal end and a distal end, said proximal end being formed integrally with said intermediate ankle section and said distal end extending forwardly to correspond to the toe of the user, said toe section curving substantially continuously forward from said proximal end to said distal end thereof such that bending stress is distributed substantially evenly therethroughout, said toe section meeting the ground at a point near said distal end of said toe section to define, together with said ankle section, a forward lever arm for said foot member for returning substantial energy to said user during toe off; and a heel member extending substantially continuously rearward and downward from a point tangential to said intermediate ankle section such that bending stress is distributed substantially evenly throughout said heel member, said heel member providing a rearward lever arm for said foot member;
said heel member and said toe section providing substantially the sole support for loads incurred by said flexible foot prosthesis during heel strike and toe off, respectively;
whereby said foot member can be readily detached from said tubular pylon member and is interchangeable with like feet members having different resiliency characteristics without having to change or adjust said socket or the length of said tubular pylon member, such that a wide range of varying activity levels may be sustained in a single prosthetic device.
20. The lower limb prosthesis of claim 19 wherein said tubular pylon member is constructed of high-strength graphite fiber in a high-toughness epoxy thermosetting resin system.
21. The lower limb prosthesis of claim 19 further comprising a coupling adapted to secure said detachable flexible foot prosthesis to said distal end of said tubular pylon member.
22. The lower limb prosthesis of claim 21 wherein said coupling comprises at least one substantially flat mounting surface adapted to closely receive said mounting surface of said upper attachment section of said foot member and at least one substantially cylindrical mounting surface adapted to closely receive said mounting surface of said tubular pylon member.
23. The lower limb prosthesis of claim 19 further comprising an auxiliary ankle member attached at one end between said upper attachment section of said foot member and said distal end of said tubular pylon member and extending downward and forward therefrom to resiliently resist deflection of said intermediate ankle section in response to flexure of said foot member, wherein said auxiliary ankle member and said intermediate ankle section cooperate to determine the bending characteristics of said flexible foot prosthesis.
24. The lower limb prosthesis of claim 23 wherein said auxiliary ankle member is slightly tapered to provide varied resistance to excessive bending of said intermediate ankle section of said foot member.
25. The lower limb prosthesis of claim 19 wherein said upper attachment section, said intermediate ankle section and said toe section of said foot member are integrally formed from superimposed laminates maintained in operative relationship by an encapsulating polymer.
26. The lower limb prothesis of claim 25 wherein said superimposed laminates taper slightly from a relatively thick portion at said upper attachment section to a relatively thin portion at said toe section in order to provide desired bending characteristics along the length thereof.
27. The lower limb prosthesis of claim 19 further comprising a cosmetic cover formed of a low-density polymer adapted to shroud said foot member during normal use.
28. A lower limb prosthesis adaptable to a socket fitted to the stump of a lower-limb amputee for providing resilient kinematic support to said amputee during normal walking, running and jumping activities, comprising:
a substantially rigid tubular pylon member having a proximal end adapted to engage said socket and a distal end extending substantially vertically downward and terminating at about the location of said amputee's normal ankle joint;
and a detachable flexible foot prosthesis comprising a spring-like foot member adapted to be selectively attached to said distal end of said tubular pylon member according to a particular desired activity or a particular desired degree of kinematic resilience, said foot member further comprising:
an upper attachment section having a substantially vertically oriented attachment surface adapted to attach said foot member to said tubular pylon member;
an intermediate ankle section formed integrally with and curving substantially continuously downward and forward from said upper attachment section such that bending stress is distributed substantially evenly therethroughout, said intermediate ankle section providing substantially the sole support for all vertical, transverse and torsional loads transmitted through said tubular pylon member to said flexible foot prosthesis;
a resilient toe section formed integrally with said intermediate ankle section and curving substantially continuously forward therefrom such that bending stress is distributed substantially evenly therethroughout, said toe section defining a forward lever arm for providing substantially the sole support for all vertical, transverse and torsional loads transmitted through said flexible foot prosthesis during toe off; and a resilient heel member extending substantially continuously rearwardly from said intermediate ankle section such that bending stress is distributed substantially evenly throughout said heel member, said heel member defining a rear lever arm for providing substantially the sole support for all vertical, transverse and torsional loads transmitted through said flexible foot prosthesis during heel strike;
whereby said foot member can be readily detached from said tubular pylon member and is interchangeable with like feet members having different resiliency characteristics without having to change or adjust said socket or the length of said tubular pylon member, such that a wide range of varying activity levels may be sustained in a single prosthetic device.
a substantially rigid tubular pylon member having a proximal end adapted to engage said socket and a distal end extending substantially vertically downward and terminating at about the location of said amputee's normal ankle joint;
and a detachable flexible foot prosthesis comprising a spring-like foot member adapted to be selectively attached to said distal end of said tubular pylon member according to a particular desired activity or a particular desired degree of kinematic resilience, said foot member further comprising:
an upper attachment section having a substantially vertically oriented attachment surface adapted to attach said foot member to said tubular pylon member;
an intermediate ankle section formed integrally with and curving substantially continuously downward and forward from said upper attachment section such that bending stress is distributed substantially evenly therethroughout, said intermediate ankle section providing substantially the sole support for all vertical, transverse and torsional loads transmitted through said tubular pylon member to said flexible foot prosthesis;
a resilient toe section formed integrally with said intermediate ankle section and curving substantially continuously forward therefrom such that bending stress is distributed substantially evenly therethroughout, said toe section defining a forward lever arm for providing substantially the sole support for all vertical, transverse and torsional loads transmitted through said flexible foot prosthesis during toe off; and a resilient heel member extending substantially continuously rearwardly from said intermediate ankle section such that bending stress is distributed substantially evenly throughout said heel member, said heel member defining a rear lever arm for providing substantially the sole support for all vertical, transverse and torsional loads transmitted through said flexible foot prosthesis during heel strike;
whereby said foot member can be readily detached from said tubular pylon member and is interchangeable with like feet members having different resiliency characteristics without having to change or adjust said socket or the length of said tubular pylon member, such that a wide range of varying activity levels may be sustained in a single prosthetic device.
29. The lower limb prosthesis of claim 28 wherein said tubular pylon member is constructed of high-strength graphite fiber in a high-toughness epoxy thermosetting resin system.
30. The lower limb prosthesis of claim 28 further comprising a coupling adapted to secure said detachable flexible foot prosthesis to said distal end of said tubular pylon member.
31. The lower limb prosthesis of claim 28 further comprising an auxiliary ankle member attached at one end between said upper attachment section of said foot member and said distal end of said tubular pylon member and extending downward and forward therefrom to resiliently resist deflection of said intermediate ankle section in response to flexure of said foot member, wherein said auxiliary ankle member and said intermediate ankle section cooperate to determine the bending characteristics of said flexible foot prosthesis.
32. The lower limb prosthesis of claim 31 wherein said auxiliary ankle member is slightly tapered to provide varied resistance to excessive bending of said intermediate ankle section of said foot member.
33. The lower limb prosthesis of claim 28 wherein said upper attachment section, said intermediate ankle section and said toe section of said foot member are integrally formed from superimposed laminates maintained in operative relationship by an encapsulating polymer.
34. The lower limb prosthesis of claim 33 wherein said superimposed laminates taper slightly from a relatively thick portion at said upper attachment section to a relatively thin portion at said toe section in order to provide desired bending characteristics along the length thereof.
35. The lower limb prosthesis of claim 28 wherein said upper attachment section is adapted to attach said foot member to a back surface of said tubular pylon member.
36. The lower limb prosthesis of claim 28 wherein said upper attachment section is adapted to attach said foot member to a front surface of said tubular pylon member.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2063504 CA2063504C (en) | 1992-03-19 | 1992-03-19 | Foot prosthesis having auxiliary ankle construction |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2063504 CA2063504C (en) | 1992-03-19 | 1992-03-19 | Foot prosthesis having auxiliary ankle construction |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2063504A1 CA2063504A1 (en) | 1993-09-20 |
| CA2063504C true CA2063504C (en) | 1998-08-11 |
Family
ID=4149463
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2063504 Expired - Lifetime CA2063504C (en) | 1992-03-19 | 1992-03-19 | Foot prosthesis having auxiliary ankle construction |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2063504C (en) |
-
1992
- 1992-03-19 CA CA 2063504 patent/CA2063504C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2063504A1 (en) | 1993-09-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |