US2667644A - Anatomical knee and hydraulic snubber - Google Patents

Description

Feb. 2, 1954 o. s. JOHNSON ANATOMICAL KNEE AND HYDRAULIC SNUBBER 4 Sheets-Sheet l Filed July 5. 1948 GEV/N .5. JOHNSON INVENTOR.

HTTONEV Feb.. 2, 1954 0, s, JOHNSON 2,667,644

ANATOMICAL KNEE AND HYDRAULIC SNUBBER Filed July 3, 1948 4 Sheets-Sheet 2 zu .55 es @QV/N 6'. JOHNSON,

INVENTOR.

Feb. 2, 1954 o. s. JoHNsoN ANAToMIcAL KNEE AND HYDRAULIC SNUBBER Filed July 3. 1948 4 Sheets-Sheet 3 76 I 'z2 50 75 42 52 74 4Q,

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IN V EN TOR.

TTOENE'V Feb. 2, 1954 o. s. JOHNSON ANATOMICAL KNEE AND HYDRAULIC SNUBBER Filed July 5. 1948 4 Sheets-Sheet 4 OQl//N- L/HNSON, INVENTOR.

Patented Feb. 2, 1954 ANATOMICAL KNEE AND HYDRAULIC SNUBBER Ojrvin Si Johnson, -Manhattan Beach, Calif., as-

signor toNorthrop Aircraft, Inc.,

Hawthorne,

Calif., a corporation of California Application'July 3, 1948, Serial No. Zi(i,957f-r 16 Claims.

The present invention relates to artificial legs for above-knee amputations, and its primary object is-to provide-an artificial leg that dupli- Cates the actionof the` natural leg ina more nearly exact manner than has f heretofore been possible; In this-connection, one of the important2 objects-.of the invention is'to provide new and-improvedI mea-ns for applying a cushioned braking action on the kneevmechanism, slightly checking or retarding the freeforward swinging movement? of the lower leg with respect to the upperlegduring-thefwalking cycle,r` so as to simulate theforward swinging rate of the natural lege Locomotion studies of human gaits have established the fact that during each complete walking: cycle, the'natural vknee locks in two separate positions; the rst being when the heel strikes the ground atvthe forwardA end of the leg swing;v and the second; being at the Arear end of thev legswing; when the weight isi-momentarily supported on the toes-duringthepush-off phase. Betweenv the rst and secondl locked positions, r While* the .bodyf' issupported onA the leg, the knee unlocksr and'exes slightly-to cushionthe shock1of impact. A" further object of; they invention, therefore, isto duplicate thisY sequence of.A` actiom anw-te provide a mechanism that eX- erts a cushioned braking action on the knee, tending to lock the sameV whenzthe heel strikes the ground, andV again during the push-off phase when .the weightis -carried'on the toes;

Another object of the invention/is to provide a mechanism responsive to the, sudden applica-- tionzof an excessive loaden the heei or toe ofthe foot; for applying'a cushioned braking action on the-kneeatianv position of flexion thereof, which will prevent the leg. fromcolla-psing under-the wearer` in the f event iof stumbling or,v momentarily 105mg. balance. The. resulting"v slow, controlled flexion of theknee checks the fall witha cushicned: action; givingthe-'amputee opportunity to recover;

Still alfurtheryobject of the* present invention is to provide an artificial leg having a new and improved knee joint mechanism that reproduces almost exactly the geometry of the natural knee. Prior'knee jointsA have,` forV the most, employed simple hinge pivots; but these fail to duplicate thenormal knee action because of the factA that the natural kneejoint is not a true hinge.v Instead,v the shape-of the femoralcondyles, andthe naturefof their4 attachment tothe tibialcondyles are-.suchthat the T tibia: glides posteriorly on the condyles` as theknee isz exed, producing. a com bination ofrrollingfand sliding movements.v Such a motion obviously could not take place about one fixed center, and an analysis of the geometry involved reveals, the fact that the ycond-yles `of the tibia glide along a curved pathl approximating thelcontour of the. femoral condylea while the rate of 'angular displacement of the tibia with respect t0Y the .femurv varies with the position` lof the tibial condyl'es` relative to the femoral condyles. As the tibial condyles approach the upper rear end of their curveczlpath,l their rate of. travel along that pathslows. down, whilethe rate of angularv displacement of the tibia accelerates.

During flexion and extension of. the knee, the length of the natural legchanges slightly as a result ofthe relative sliding. movement between the tibialandfemoral condyles, and this` changing length enters into vthe pattern ofmuscular activity and bodily coordinationduring the walking cycle to produce the, smooth.rhythmicI motion characteristic of thenormal gai-t.v When alsingle pivot is usedattheknee, the leg remains at a Vconstant, lengthfor all positions of flexion and extension, and the amputee. iindsthatthe foot tends tostrikethe ground during the swinging phase of the walking cycle, unless compensated for by rolling-,the hips or by-raisingslightlyon the toesof the other, foot. The result-of such compensatory movement is a. limping gait. The improved knee JOint. mechanism of the present invention. reproduces in the articial leg the same, lengthening and. shortening action which takes place in thenatural leg, makingit possible for the amputee to vWalk with a symmetrical and natural gait.,

Anotherl object of the invention is. to provide an artificial leg embodying the features described above, whichA is, at, the same time, extremely simple irl-construction, smoothvandsilent in operation, andffree from trouble.

The foregoingr andother objects and advantages ofthe presentY invention will become-apparent to thoseskilled in the -art upon considerotion of the following. detailed description of the preferred embodiment` thereof, reference being had to theaccompanying drawings, wherein:

Figure l. issaperspective view of an artificial leg embodying. the. principles of the invention;

Figure 2, isapartially'cutaway side elevational view of the saine;`

Figure 3 .is `av front elevation .of the. leg;

liigure tris.; a, sectional view through the ankle andfoot, showing. the manner inwhich thehydraulicsnubberj control` mechanism is actuated by. lnzlwardlv deilection,l of the toe portion under load;l l i Figure 5 .is a View.similarA to. Figure 4., butshow` ing the ,manner in which thecontrol mechanism is actuated by plantar exion of the foot;

Figure 9 is a side elevational view of the knee 1110 mechanism bent to approximately'90;

Figure 10 is a schematic diagram, showing the manner in which the geometry of the natural knee was derived; Y

Figure 11 is a side elevational view of another form of the invention embodying a single pivot knee mechanism with a hydraulic s'nubber for checking the forward swinging movement ofthe lower leg with respect to the upper; and

Figure 12 is a front elevational View of the same.

Before launching into the detailed description of the construction and operation of the preferred 4 the load center line of the tibia for the position of the condyles shown in Figure 10. Points ai to a9 and b1 to b9 were then plotted for nine different positions of the tibia, following which, cor- `responding pairs of points were connected, and `perpendicular bisectorsrci to C9 were erected. It

might be well to explain, at this point, that the nine positions of the tibia giving the above-mentioned points in Figure lvare not spaced apart iii '10 increments, as in the case of the X-ray photographs, but are merely nine arbitrarily selected positions lying on the patternv obtained from the X-ray pictures.

Y The points of intersection of each of the lines c with its corresponding line d-b, were then connected by a smooth curve C, which might be for the tibial condyle.

Vfound by plotting the points di to da formedv by 20.

embodiment of my invention, it might be well to describe briefly the preliminary steps which were necessary in order to derive the geometry of the natural knee in flexion, so that the action might be accurately duplicated in the mechanical knee.

The first step of thepreliminary investigation was to take a series of X-ray pictures of the naturalV knee in progressive stages of flexion, using 10 increments from the eXtended-leg'position of 2 hyper-extension, kto the fully vexed position of approximately 135. Vellum tracings of the femur and tibia were then taken from these X-ray pictures, and the tracings used as templates to make upplastic models of the bones and their condyles. These models were then placed on drawingY paper in the exact relative positions occupied by the bones in the series of X-ray pictures, and a composite drawing was made, comprising a series of superimposed outlines which were drawn around the vmodels; keeping the femur in a single xed position, and changing the position and angularity of the tibia.

The outlines and relative positions of the femoral and tibial condyles for the fully extended leg condition are shown in broken lines at F and T,

respectively, in Figure 10. It will be noted that L evident, Vfrom termed the centrode curve of the load center The centrode, itself, is

the intersection of eachof the lines c with vthe preceding" line c.V Thus, pointdi represents `the intersection of line c1 with line co; while d2 designates theintersection of c2 with c1, and so on.

The generally triangular ligure D in Figure l0 iis' the centrode of the tibiaand clearly illustrates the eccentric displacement of vthe instantaneous centerl of rotation of the tibia which takesplace Since the center of load une for 'the tibiagudes Ypcsteriorly along the centrode curve C, it became the start, that the pivot axis of a mechanical knee would have to follow the same curved path C, and that the Yangular position of the lower leg component about the said pivot axis would have to be controlled in some manner 1 as ,af function of the linear positionef the pivot axis along the curve.,

VInasmuch as the curve C is non-circular, it was "deemed that the pivot axis Could best be heid to that path by a system of interconnected linkage operating from two fore and aft spaced points on the upper leg component, and that the angularity Vof the lower leg component might be controlled by a link connected into therst-named linkage. It was from the foregoing derivation and analysis of the geometry of the natural knee that the anatomical knee ef the present invention was the tibial condyle has an upwardly curvedloadbearing surface, which is separated VVfrom the 5 femoral condyle by an appreciable distance. This space is occupied, in the normal knee, by elastic cartilage which provides a cushion between the condyles.

In order to nd the centrode of the tibia, which might be defined as thev path of the instantaneous center of pure rotation of the tibia as it moves with respect to the femur, it was deemed subsequently borne out by the ultimate results. The location of the load center line was established by selecting the two points do and bn on the tibial condyles at the ends of the load bearing surface. These points were connected by a line, Y Vand the perpendicular bisector co of that line was then constructed. The line co represents developed.

The principles of my invention will best be understood by referring now to Figures l to 9, inclusive, wherein the articial leg representing the preferred embodiment of the invention is designated in its entirety by the reference numeral 20, and is seen to comprise upper and lower leg components 2l and 22, respectively, which are connected together by a knee joint 23 for relative swinging movement. Mounted on the bottom end of the lower leg component 22 is a foot 215 having a hinged toe portion 25. The upper legv component 2l may take any desired form, and in the present instance comprises a suction socket 26 of the type which isad'apted to be held on the stump by a slight suction pressure within the socket.

Attached to the bottom of the suction socket 26 and preferably adjustable angularly with respect thereto about a vertical axis, is a base mem- Vand spaced a short distance laterally from the flange 3l; the two flanges 33 and t! being drilled to receive a transversely disposed front pivot tshaft 34, and the flanges 32 and 3l being drilled to receive-a rearV pivotf shaft 3.51 which'isparallel to thefront pivot shaft andspaced" rearwardly from andslightly above'thelatter. The: pivots Stand 35 are the two fore -and'raftspacedpoints about which the knee linkage operatesq to move the lower leg pivotaxis along a path corresponding to the'eentrod'e-curva@ of lf"igure 10i- T-he lower legl pivot axis, referred toin the claims asthe third pvot, isdesignatedin the draw-ings by theY reference numeral 36': As best shown in Figure 8; the pivot aXis-tiiextends Coaxially through the cylindrical chambery 3l and operating shaft 381 oia hydraulicv snubber lll). The hydraulic snubber` lll-'comprises a housing l1 which is lxedly mounted on the topendofi a tube 12- forming the shank of the lower leg component 22. rlhe lower leg component 2251s preferably, although not necessarilyv of the pylon type shown in the drawings, butmight take any other desired form. In the case ofI the pylon construction shown herein, the tube 2; kneel-I3, and.z ankle d3 may be enclosed by a cosmetic shell for the salie of improved appearance and to protect the clothes.

Projecting laterally from one end of the hous ing il coaxial with the pivot axis Sis a stud te' that forms the pivot connection for one-ofthe links L35 in the knee mechanism; said link being journaled on a bushing dii which is pressedonto the stud. At the opposite end of the housing di and' also coaxiall with thepivot axis 36 is another stud 2l which projects from the outer face of a cover platermember- 5G. Stud el formsl the pivot connection for anotherY link 5i in the knee mechanism, and to this end is provided with a f bushing 52: The-member 5d isattached to the outer end of housing @l by aplurality of bolts, and hasv a cylindrical portion 53 (see Figure 8) projecting into the cylindrical chamber 3l. A circumferential groove 54 is cut into the periphery of the cylindrical portion and av rubber O-ring .'55V is seated within the groove tov seal the clearances between the cylindrical'porticn' and the inner wall of chamber 3'?. The member 5i) is formed with a cylindricall bore It which receives the operating shaft 33, and the inner end ofthe latter is journaled in a bushing 631 which is pressed into a'rrecess El in the inner end w-all of the housing di. The outer end of theshaft 33' projects beyond the stud il and is serrated at t2' to receive a link 63-in a rigid interconnection. A split ring tellsy seatedwithin a groove in the end of shaft 3&2 to hold the'link 63 in'place. An annular channel is formed in they surface of the bore 55, and seated therein is an O-ringA 6l which seals the clearances between the shaft 38 and bore et.

Formed integrally with the member eti and projecting laterally therefrom to the inner end of the chamber 3l is a wedge-shapedpa1tition member which is shaped' to illthe space between the wall of chamber t'l'f and the peripheral surfaceV of' shaft 38'. A cylindricalrv valve: charnber l! extends into the partition 'it from the inner end: thereof, and' rotatable within: this chamber is a valve plug T2 having a generally cone-shaped port l3- provided therein, the purpose of which will become apparent. presently. The valve plugv 'l2 has a'steml'fl projecting axially therefrom through an opening inthe housing 41, and mounted on the outer end of the: stem is` an operating arm l5. An O-ring le sealsl the stern 'la against leakage.

rwo passagewaysV 8a; and 6l are-4` d-rilledv. into the valvechamber lh from' opposite; sides.I off thel partition' 1u", and these passagewaysn cooperate with/the" valver port. T3? toY providefrestricted communication betweenvl the two-.sides of the partition. 'ItheLcylindrical chamber 3i? is lledwith hydraulicfluid,`l whch'is forcedlthroughthe passageways-inthe partition 'l0.by a vane 82 on the shaft 3S. The vane S! isk keyedinto the shaft 38 and cooperates with the partition member l) todivide the-chamber 31 into two compartments. As the Vane 82: rotates with the shaft 38, nuid is-'forcedfromsone ofthe compartments through the-passages 8U; ai; and-valve port 'lt'into the other compartment. Asshown-in Figure 7, the valve plug l2 is normally positioned so that the port- I3 is fully registered with passageways 8U and; gli When the valve plugA l2 isA rotated in a clockwise-v direction, the small end of the valve port l3fpasses beyond theopening of passageway thereby stopping the circulation of iluid from one side of the partition to the other. The large endof valve port '13,A however, remains in communication with passageway ti when the valve is closed, with the result that high pressure nuid in line-'81 causes the valve plug 'l2 to be pressed tightly-against its seat at the far side of the .chamber 1l; thereby sealingy the valve against leakage. A wiper-seal d3 around the edgesy of vane 82 closes the clearancesbetween the vane and the walls of chamber 3l against leakage.

They construction an'darrangement of the linkage in the knee mechanism Ztl-will best be understoodY by referring now-to Figures 2 and 3, wherein it will be seen that link et isconnected at its top end by a pivot bolt te to one arm 87 ofthe bell crank 38; The bell crank t is journa'led'on the front' pivot shaft tl between supporting flanges Si and 335 and has a second arm 3Sv spaced 180i from arm 821; Arm d'2' extends downwardly and rearwardly trom pivot 3d, while arm 891 extends upwardly and forwardly therefrom, and is connected by a pivot bolt se to the front end of a-link- QI'. The'rear end of link di is connected by a pivot bcltt2 toanlarrn $33 of a bell crank 94 which is journaled on the rear pivotf 35. Another arm- @5f of` the bell crank all extends downwardly andl forwardly from the pivot 35* and isconnected by a pivot bolt Se to the top end'of link 45.

It will be noted in-Fgure 3 that the hub of bell cranh- 9dv is quite elongated and extends across the width of the base member Slfrom flange El to flange 32.' Arm 53 is at the leit hand endof the bellcrank 9e; while arm. is at the right handr end thereof;` Another arm t? (see Figure 1) extendsL downwardly and forwardly trom the bell crank.` '.'ltf parallel to arm. S51 and of the same length asthevlatter, but at. the same end of the bell crank as armv 83'. ArmV elle connected by a pivot bolt ltonlink 55S which is'parallel andedual inlength to link` 45.; andthe two laterally spaced arms 95, 9T, and-links-fi 51; provide lateral rigidity-.I in.. the'. knee .structure;

Anotherarm 95S.extendsdownwardly and rearwardly, from theA bell crank: .filliadjacent the arm 95', andthislast-,namedA army is connected by a pivot bolt' Mw' tok a forwardly extending link ltl. The front end ofthelink mi. is connected by a pivot; boltf lll'itoy an. arm le@ which is formed integrally withthe'housing al. and extends upwardly: and; forwardly therefrom.

The linkage system formedl by links 55', 5,9, t1?. and; 9|, andlby: bell cranks Stand te! serves to control: the: travel.; of: the;l bottom pivot; 35 to a curved path:substantallydentical to the; centrode curvefC shown-inzFgure 10; Whilebell .crank arm 99 and link IUI serve to stabilize the lower leg about the bottom pivot 35 and to control the angularity of the lower leg to the-flexion pattern indicated by the lines ca -o9. The particular geometric patterns of Figure 1G are obtained in the mechanical knee 23 by virtue of certain angular relationships and proportional lengths which will now be described.

Reference is had now to Figure 2, which shows the knee 23 in the extended-leg position. 1n this condition, link 55 is disposed at an angle of approximately 135 to bell crank arm Sl, while the other bell crank arm 3S is disposed at an angle of approximately 62 to link 9|. Each of these angular relationships is measured as the included angle between intersecting lines drawn through the centers of the pivot connections at the ends of the members involved. Link 9i is at approximately 92 to bell crank arm $3, while the latter is approximately 135c to bell crank arms 95 and l, respectively. Bell crank arm 55 is approximately 58 to bell crank arm or 167 to arm 93. Link l5! is at approximately 62 to arm S9, and approximately 74 1K2" to a line drawn through the center of pivot bolt it and bottom pivot 35. One other angle which enters into the picture is the included angle between the axes of pivots 35, 35 and 35; the said angle being approxi mately 28. Y y

The proportional lengths of the several parts are best disclosed by giving the actual dimensions, in inches, of a typical knee designed for a man of average height and bone structure. The center-to-ccnter distance from pivot axis 35 to pivot bolt 55 (i. e., the effective length of link 53) is approximately 33/8. The center-to-center distance from pivot bolt 85 to pivot 35, and from 34 to pivot bolt 95 is 1" and l", respectively. The distance from the center of pivot bolt 55 to pivot bolt 92 (the effective length of link 9|) is approximately 21/2". The distance from the center of pivot bolt 92 to the axis of pivot 35 is approximately l1/4, while the distance from the axis of pivot 35 to the center of pivot bolt 55 is approximately 11/4". The distance from the center of pivot S5 to pivot axis 35 (i. e., the effective length of link 65) and from pivot bolt Q3 to pivot axis 35 (the effective length of link 5l) is approximately 3%," each. The distance from the axis of pivot 55 to the center of pivot bolt |55 (bell crank arm 59) approximately 2-g; from the center of pivot bolt 55% to the center of pivot bolt H32 is approximately .B3/8; and from the center of pivot bolt |52 to the pivot axis 35 is approximately 2%". lt should be understood that the actual dimensions given above are not, in themselves, significant, but rather, it is the proportional lengths of the several members with respect to the others that is critical. in the case of a man of shorter than average height, the correct lmee action would be obtained by reducing all of the dimensions by the same proportional amount; while the reverse procedure would be followed in the case of a man of greater than average height. The angular relationship between the several parts, would, of course, remain the same for all sizes of the knee mechanism.

It might be noted at this point that when the leg is fully extended, as in Figure 2,7the axis 36 of the hinge pivot is located posterior to the vertical line of the center of gravity of the body, causing the pivot to go past the centerline as the leg is extended, giving about two 'degrees of hyper-extension, which' gives stability to Athe `joint. The knee joint is stopped at this 2 of 'hyper-extension by means of a limit stop bracket |05 which straddles the front edges of flanges 3| and 33. A strip |55 of composition material is attached to the inside face of the bracket |55 and serves as a bumper for the bell crank arm S5 to limit the counterclockwise rotation of the latter.

When the knee is flexed, the rearward swinging movement of the lower leg 22 about the pivot axis 36 causes the arm |03 to swing downwardly and forwardly ina counterclockwise direction (Fig. 2), pulling the link forwardly and rocking bell crank 94 in a clockwise direction. Bell crank 9d, `acting through link 9|, rocks the bell crank 88 in a clockwise direction. As the pivot moves downwardly and forwardly with clockwise rotation of bell crank 88, the distance between front pivot 34 and bottom pivot 35 increases -at a diminishing rate of'change, while the distance from pivot axis 36 to rear pivot 35 decreases yat an increasing rate of change. This condition continues until the lower leg component 22 reaches an angle of about 50 to the upper leg component, at which point the pivot bolt 85 passes dead center between pivots 35 and 35. 1From that point on, the distance from pivot 34 to pivot axis 36 decreases at an increasing rate of change, while the distance between rear pivot 35 and bottom pivot 35 continues to diminish at an accelerated rate of change.

One of the more important aspects of the invention has to do with the application of a cushioned braking action on the knee 23 responsive `to plantar flexion of the foot 25, or to upward deflection of the hinged toe portion 25. This braking action gives the same sequence of locking and unlocking at the knee which is obtained in the natural leg during the walking cycle, and also enables the amputee to recover from a fall by restraining the flexion of the knee Ato a slow, controlled rate when the weight is thrown suddenly on either the heel or toe portion. Still another advantageous feature of the above-mentioned locking action is that it enables the amputee to walk down an inclined surface without having the knee fold up beneath him.

The braking action referred to above is obtained by controlling the valve 12 in the hydraulic snubber lll with linkage means actuated by the foot 24 and hinged toe portion 25. To this end, the operating lever 15 of the valve 'i2 is connected by a link |||l to a lever arm which is pivoted at ||2 on the snubber housing 4|. A push-rod H3 is connected at H4 to the arm and extends downwardly therefrom through the center of the hollow tube 42. The bottom end ofthe push rod extends through and is slidable within a guide bushing I l5 which is pressed into a hole in a circular plate H6 at the bottom end of the tube 42; said plate being held in place by a cap member |26 which is riveted or otherwise suitably fixed to the bottom end of the tube 42.

The cap member |25 has a pair of laterally spaced ears |2| on the bottom end thereof which are drilled and bushed to provide a journal for a transverse tubular shaft |22, forming the hinge pivot foi` the angle 43. The ends of the tubular shaft |22 project beyond the ears i2| and are xedly received within holes in the ends of arms |23 of a saddle member |24. A thread-ed stud |25 extends downwardly from the bight portion of the saddle IM through a hole in the foot 2d, and is secured by a nut |26.

Projecting forwardly from the front of the cap member |20 at the lower end thereof is a horizontal shelf |35, whichis engageable with the top 'rend Yof .a rubber instep bumper |32'that is setinto a recess inthe top surface of thefoot, An upwardly-inclined rear shelfv 53| projects from the back of member |25 and is vengageable with the top end of a rubber heel cushion |33. The two .cushions 32 and i engage their respective shelves to locate the ioot in its normal position, as shown in Figure 2. The instep-cushion |32, being rather short, permits .only .a very liniited amount of dorsiiexion of the foot, while the heel cushion |33, being quite long vand resilient, permits a greater degree of plantar flexion.

The toe portion 25 is connected to the Vfoot-.lili by a transverse hinge |35 which permitsA the toe to deflect upwardly with respect to the foot. The r toe portion 25 is yieldingly held in the extended position shown in Figure .2 by a rubber cushion |36 which is compressed, as shown in Figure 4, when the toe portion is deflected upwardly. Mounted onv the back side of the toe `portion. .25 is a bracket tite that is connected :by a `pinziti to the front end of a turnbuckle link |62; the rear end of said being'connected ibya pin 43 to an arm idd extending downwardly from a cam M5. rIhe cani l is journaled on the ankle pivot shaft i222 between the ears 25, and is provided with a lobe fl which is normally positioned las shown in Figure :2. Bearing downwardly on the peripheral edge of the cani Edt from above is a cam follower, preferably in the form of a roller i@ which is coniined within a `U- shaped recess i lin the bottom of .a `guide member |52. The guide member i5?! is screwed onto the bottom end of push rod lit, and is provided on its front and rear sides with flanged portions,I

which slide up and down in vertical ways |f53in the cap member Eile. The roller itil is held downwardly `against the periphery of the cam lli-5 by ya compression spring itil which encircles the push rod i i3 and bears downwardly against Ya spring keeper 555. The roller i5@ is confined against axial displacement from the recess Edi by the side walls iii (see Figure 6)of the cap member |21, which lie nclosely adjacent the -ends of the roller.

When the hinged toe portion bis deilected upwardly with respect to the foot,.as shown in Figure 4, the turnbuckle link M2 is. pushedrearwardly,.rocl=:ing the cani ide in a counterclockwisedirection. The roller tot is lifted by the cam lobe pushing the roti M3 upwardly and raising the valve operating lever l5, which closes the valve port i3 with respect to the passageway 8o. Flexion of the knee causes the vane 82 to rotate in a clockwise direction, as seen in Figure 7, and this forces hydraulic iluid from the bottom side of the partition it' to the top side thereof through the passageways Si, :and valve port l. Partial closing of the valve member i2 throttles this now of hydraulic fluid through the partition member, creating resistance to rotation of the vane 232 and thereby restraining the knee against further flexion. 't/'hen the kweight is removed from the toe portion 2o, the resiliency of rubber cushion i235 causes the toe portion to be returned to its initial position, thereby restoring the cam member'i to the position shown in Figure "2; while the spring urges the push rod iifdownwardly to reopen the valve member l2.

The hydraulic snubber valve l2 is also 4moved toward the closed position when the footiltis deilected to the position of plantar flexion shown in Figure 5. This is the condition which is .obtained when the weight is thrown on theheel at the end of the forward swing'phase fof the'leg duringzthe-walking cycle. Theiresistance of the rubberfcushion |36 toco-mpression causes the toe portion 25 to 'be heldin its normal position, with the result that theiturnbuckle'link |42 and cam ist yremain'stationary with respect to the foot while the latter is rocked about the ankle pivot |22. As thecarn-llrotates with the foot, the lobe'fill raises the rollerfltiil and thek rod i i3 uplwardly-againstrthe pressureoi `spring |54, to rotate the valve plug?? toward' the closed .positlon. Whenithe weight is removed from the heel, the 'resiliency of the compressed heel bumper i 33 the foot to be' returned` to its normal posi- Y tion,rwhichhas the-eiect-oflrestoring the valve ping l? to its normal open position.

Another .forni of the invention, featuring the hydraulic snubber-and brake ina singlepivot kneefis shown in- Figures l-4and 15, to which refence will-now rbe had. :In this embodiment,.parts having thefsamefunctions -as those in Figures `1 to l0 -have been `giventhe sainereference numerals lwith the-suffix fof The base member'lla has two laterally spaced, downwardly extending fears iet and which pass down overopposite ends of the hydarulic snubber housing l4l, which is xedly mounted on the topi-end of the lower ieg tube 220. Ear |61 is drilled toreceive-thestationary stud vifi-0L at one end of the housing Ma, `and is rotatable thereon. Mlil-ar ilisdrilled -coa'Xi-al 'with the hole in the `other :earfand receives the serratedl projecting end of the operating shaft Y33a of Vthe snubber. The operating shaft 330: is thus held stationary with respect to the upper leg component .2 lo, whilethe snubber housing lila, being rigidly mounted on the upper end of the lower leg. component 22a, rotates 'with' the latter. rEhe mechanism in thehydraulic snubber :etais-the same as that-shown in Figures 7 and'S, and therefore need not bedescribedin detail again. The control .mechanism in the foot for operating the valve ofthe hydraulic snubber is likewise the same as that shown in Figures 4, 5 and 6, and its operation is also-thesame. Thus, the hydraulic snubberand the controlmechanism for applying a cushioned braking .action fon vthe flexion of the knee Ais adapted for use in a .single pivot 'knee as well as in an anatomical knee or" the type shown in Figs.' 1 to 1G.

While Il have shown rand `described in `cony sideral-ble detail what I believe to bethegpreferred form of my invent-ion, it to beunderstood that such .details are not restrictive, land that" Various changesr `may be Vmade `in vthe shape fandarrangement of the several parts withoutidepartingfrom the ybroad scope of'the'invention,.asldeiined in the appended' claims.

.I claim:

1.In an articialleg havingtupper and lower leg components, vand a knee; joint -.connecting Asaid components togetherfor relativeiswinging movement, aA hydraulic rsrrubberzror vcheck-ing thea relativeswinging:movement :of said components cornprising, in combination, a housing attached ."to one of said components, said housing having .a cylindrical chamber ,.forined therein .concentric with the pivot axiso'fsaidtknee joint, sai'olrchan ber being rllleol` with hydraulic iluid, a rotatable shaft disposed coaXially cwithinsaid chamber .and connected to .the .other of said componente vforrotation therewith, va valieron said shaft, .a 4partition extending from the sidewall or" said .chamber to thefzperiphery oisaiidzshaft and .cooperating with said Nvane "to 'divideisaidvchamber. into two` conipartments`,=andi restricted passage means interconnecting said COmpartmentswhereby fluid displaced from one of said compartments by rotation of said vane is forced through said restricted passage means, creating resistance to rotation of said Vane and shaft, and thereby retarding the swinging movement of said leg components with respect to one another.

2. In an artificial leg having upper and lower leg components, a knee joint connecting said components together for relative swinging movement, and a foot pivoted on the bottom end of said lower leg component and having a hinged toe portion, a hydraulic snubber for checking the relative swinging movement of said components comprising, in combination, a housing attached to one of said components, said housing having a chamber formed therein which is filled with hydraulic iluid, a movable member disposed within saidchamber and dividing the saine into two compartments, said member being attached to the other of said leg components for movement therewith, valve means interconnecting said compartments, whereby fluid displaced from one of said compartments by movement of said member is forced through said valve means into the other compartment, a cam rotatably mounted on said foot coaxial with the pivot axis thereof, a link connecting said cam with said toe portion, whereby the cam is rotated when said toe portion is deflected upwardly about its hinge, and means operable by said cam for closing said valve means to increase the resistance to angular movement between said leg components either when said foot is displaced in plantar flexion or when said toe portion is deflected upwardly within respect to said foot.

3. In an artificial leg having upper and lower leg components, a knee joint connecting said components together for relative swinging movement, and a foot pivoted on the bottom end of said lower leg components, a hydraulic snubber for checking the relative swinging movement of said components comprising, in combination, a housing attached to one of said components, said housing having a cylindrical chamber formed therein concentric with the pivot axis of said knee joint, said chamber being lled with hydraulic fluid, a rotatable shaft disposed coaxially within said chamber and connected to the other of said components for rotation therewith, a vane on said shaft, a partition extending from the side wall of said chamber to the periphery of said shaft and cooperating with said vaneto divide said chamber into two compartments, valve means providing communication between said compartments, whereby uid displaced from one of said compartments by rotation of said vane is forced through said valve means into the other compartment, and means responsive to angular deflection of said foot with respect to said lower leg component for closing said valve means to increase the resistance to relative swinging movement between said leg components.

4. In an artificial leg having upper and lower leg components, a knee joint connecting said components together for relative swinging movement, and a foot pivoted on the bottom end of said lower leg component, a hydraulic snubber for checking the relative swinging movement of said components comprising, in combination, a housing attached to one of said components, said housing having a cylindrical chamber formed therein concentric with the pivot axis of said knee joint, said chamber being lled with hydraulic fluid, .a rotatable shaft disposed coaxially within-v said chamber and connected to the other of said components for rotation therewith, a vane on said shaft, a partition extending from the side wall of said chamber to the periphery of said shaft and cooperating with said vane to divide said chamber into two compartments, valve means providing communication between said compartments, whereby iluid displaced from one of said compartments by rotation of said vane is forced through said valve means into the other compartment, a cam attached to said foot and rotatable therewith, a cam follower bearing on said cam, and linkage connecting said cam follower with said valve means, whereby the latter is moved toward the closed position to increase the resistance to angular movement between said leg components when said foot is displaced in plantar flexion.

5. In an artificial leg having upper and lower leg components, a knee joint connecting said components together for relative swinging movement, and a foot pivoted on the bottom end of said lower leg component and having a hinged toe portion, a hydraulic snubber for checking the relative swinging movement of said components comprising, in combination, a housing attached to one of said components, said housing having a cylindrical chamber formed therein concentric with the pivot axis of said knee joint, said chamber being filled with hydraulic fluid, a rotatable shaft disposed coaxially within said chamber and connected to the other of said components for rotation therewith, a vane on said shaft, a partition extending from the side wall of said chamber to the periphery of said shaft and cooperating with said vane to divide said chamber into two compartments, valve means providing communication between said compartments, whereby fluid displaced from one of said compartments by rotation of said vane is forced through said valve means into the other compartment, and means responsive to upward deflection of said toe portion about its hinge pivot for closing said valve means to increase the resistance to relative swinging movement between said leg components.

6. In an artificial leg having upper and lower leg components, a knee joint connecting said components together for relative swinging movement, and a foot pivoted on the bottom end of said lower leg component and having a hinged toe portion, a hydraulic snubber for checking the relative swinging movement of said components comprising, in combination, a housing attached to one of said components, said housing having a cylindrical chamber formed therein concentric with the pivot axis of said knee joint, said chamber being filled with hydraulic fluid, a rotatable shaft disposed coaxially within said chamber and connected to the other of said components for rotation therewith, a Vane on said shaft, a partition extending from the side wall of said chamber to the periphery of said shaft and cooperating with said vane to divide said chamber into two compartments, valve means providing communication between said compartments, whereby fluid displaced from one of said compartments by rotation of said vane is forced through said valve means into the other compartment, and means responsive either to angular deection of said foot with respect to said lower leg component or to upward deflection of said toe portion about f its hinge for closing said valve means to increase theY resistanceto angular movementbetweenfsaid leg components.

f7. In an artificial leg'having upper' and lower leg components, a knee joint connecting said componentstogether for relative swinging movement, and a foot pivoted lon the bottom -end of said lower leg component and havinga hinged toe portion, a hydraulic snubber for checking ythe relative swinging movement 'of said components comprising, in combination,a housing attached to one of said'components, said housing having a cylindrical chamber formed therein concentric with the pivot -aXis `of said vknee joint, said chamber being filled with hydraulic fluid,-a rotatable shaft disposed coaxially within said chamber and connected to the other -of :said-com-ponents'for rotation therewith, a vaneon said shaft,a partition extending from the side'wall-of-said chamber tothe periphery of said shaft-and cooperating withv said Vane to `divide saidvchamber-into two compartments, valve means providing com-munication between said compartments, wherebyduid displaced from done of said compartments by -rotation of 'said vane-:fis forced through vsaid valvemeans into vvthe other-compartment, a cam -rotatably mounted on zsaid foot coaxial with the pivot axis thereof, a link connecting said cam with said .toe portion, whereby the cam is rotated whenv said toe portion vis deiieoted upwardly about its hinge, and '.meansoperable by said cam for closing said-valve means to increase the resistance to angular movement between said leg components when `said -foot is displaced in plantar flexion or whenfsaid 4toe portion is deiiected upwardly with respect to said foot.

V8. In an artincial leg having upper and lower leg components, a knee joint connecting said components together for relative swinging movement, comprising front and rear pivots on said upper leg component A'which are spaced apart from one another in afore and aft direction, a third pivot on `said lower leg component spaced downwardly from said front and rear pivots, the included .angle lbetween said front pivot, third pivot, and rearpivot Abeing approximatelyvZS?, a bell crank .journaled on said front pivot and having an arm'extending downwardly and rearwardly therefromga link connecting said third pivot with vsaid arm, the included angle .between said linkY and said arm being approximately 135, another bellfcrank journaled on said rear pivot and having an arm extending downwardly and forwardly therefrom, a link connecting said-third pivot with said 'lastnamed arm, the included angle between said last-named link and said last-named arm being approximately 168, said iirst-named'bell cran-khaving a second arm disposed at -180`to the first-named arm thereof, said last-named bell:Y crank having a second arm extending upwardly and forwardly from the pivot-axis -thereof at an angle of approximately 1135to the vfirst arrnthereof, a link connecting saidlsecond-arm Of-Sa'id first-named bell crank with-said second yarm -of said last-named bell crank, said links and 'said bell cranks coacting with one -anotherto constrain the'movement of saidithird pivot to'a'rearwardly and upwardly curved,non-circular path corresponding to the centrodecurve of the loadV center' for the tibial condyles ofthe natural knee, a third arm extending downwardlyA and rearwardly from said last-named-bell crank at an angle of approximately 58 to the iirst arm thereof,l a link' connectingsaid'thirdarm'with said lower leg component at'a point spaced upwardly and forwardly' from* said third pivot, the in'cludedi angle between vsaid third arm and said last-named link being approximatelyeZ", and the included angle between said last-named link and a ,line drawn through thepivot axis of its'connection to said lower legcomponent and the center of said third pivot being approximately 74, whereby said lower leg component is constrained vto rotate about said third pivot in a manner closely approximatingthe angular flexion pattern of the tibia in the natural leg, a housing mountedon said lower leg component, said housing having a cylindrical chamber formed therein concentric with the axis 4of said third pivot, said chamber being filledwith hydraulic-fluid, a rotatable shaft disposed coaXially within said chamber and having a vane mounted thereon, a partition extending'from .the side wall of said chamber to the periphery o-f said shaft and cooperating with said vanetto divide said chamber into two compartments, said shaft being nxedly attached to the link connecting said third pivot with the first-named arm on said last-named bell crank, whereby said shaft is rotated with said link, and restricted passage means interconnecting said compartments, whereby fluid displaced from one kof said compartments by rotation of said vaneiis forced through said restricted passage means, creating resistance to rotation of said vane and shaft, and thereby retarding the swinging movement of said leg components withv respect to one another.

9. A prosthetic knee joint comprising: an upper knee joint member and a lower knee joint member connected to each other by means of -a horizontal `pivot shaft; a pump housing including a substantially cylindrical hydraulic pump chamber iixedly connected to one of said members, said pump chamber being concentric with and surrounding the end of the pivot shaft; a radial vane carried by the end of the pivot shaft within said pump chamber, said shaft being connected to the other of said joint members; a stationary radial partition in said chamber, said partition'and vane dividing lthe pump chamber into two variabley volume chambers; a by-pass conduit connecting said variable volume chambers; and a valve means in said conduit for selectively opening and closing the conduit.

10.` A prosthetic joint comprising: an upper jointmember and a lower joint member connected to each other by means of a horizontal pivot shaft; a pump housing including a substantially cylindrical hydraulic pump chamber nxedly connected to one of said members, said pump chamber being concentric with and surrounding the end of the pivot shaft; a radial vane carried by the end of the pivot shaft within said pump chamber, said shaft being connected to the 'other of said joint members; a stationary radiallpartition in said chamber, said partition and vane vdividing the pump chamber into two variable volume chambers; a by-pass conduit connecting said variable volume chambers; and a valve means in said conduit for selectively opening and closing the conduit.

l1. A prosthetic joint adapted 'to pivotally join two prosthetic vlimb members together and adapted to `be controllably locked in any selected positionfwithin its operating' range of relative pivotal movement, comprising: a liquid-containing hydraulic pump including a relatively movable pumping element and casing and a lclosed circuit from outlet to inlet thereof; and a valve in sai'd closedcircuitgsaid pumping element being operatively connected to one of the limb portions and said casing being operatively connected to the other of the limb portions whereby relative pivotal movement of the two limb portions causes said pumping element to move with respect to said casing to force liquid through said valve when open, and whereby closure of said valve will prevent said passage of liquid therethrough to immobilize the pumping element and casing, thus locking the limb portions in a selected position.

l2. A prosthetic joint adapted to pivotally join prosthetic upper and lower limb portions and adapted to be controllably locked in any selected position within its operating range of relative pivotal movement and controllably unlocked for damped relative pivotal movement, comprising: a base adapted to 'be attached to one of said limb members and provided with spaced, parallel ears having laterally alined ports therein; a shaft carried by said ported ears and connected to said one of said limb members; a hollow, cylindrical, liquid-containing drum mounted on the other of said limb members parallel to said ears, with the shaft rotatably passing through the center thereo; a ported plug closing one side of said drum; a valve mounted in the said ported plug to control passage of the liquid through said ported plug; a rotor vane movable in said hollow drum and operably connected to said shaft, said rotor vane being in sliding contact with the walls of said drum to divide the latter into two variable volume chambers separated by said plug, said vane being rotatable with said shaft by relative pivotal movement of the said upper and lower limb members to force liquid contained in the drum from one of said variable volume chambers through the ported Vplug into the other of said chambers whenever the valve is open and to restrain the upper and lower limb members against relative movement when the valve is closed; and selectively operable means for opening and closing said valve.

i3. A prosthetic joint adapted to pivotally join prosthetic upper and lower limb members together and adapted to be controllably locked in any selected position within its operating range of relative pivotal movement and controllably unlocked for damped relative pivotal movement comprising: a base adapted to be attached to one or" said limb members and provided with spaced, parallel ears having laterally alined ports therein; a shaft carried by said ported ears and adapted to be connected to said one of said limb members; a hollow, cylindrical, liquid-containing drum mounted on the other of said limb members parallel to said ears, with the shaft rotatably passing through the center thereof; a ported plug closing one side of said drum between the shaft and the periphery thereof; a rotary valve mounted in said ported plug adapted to allow the passage of liquid through said ported plug when open and to prevent the passage of said liquid therethrough when closed; a rotor vane radially positioned in said hollow drum between the interior circumferential wall thereof and the shaft passing through the center thereof, said vane being operably connected to said shaft and dividing said drum into two annular, variable volume chambers separated by said vane and said plug, said vane being arranged to be rotated with respect to the drum by relative pivotal movement of the prosthetic upper and lower limb members to force liquid contained in the drum from one of said variable volume chambers through the ported plug and valve into the other of said variable volume chambers whenever the valve is open, and said vane being relatively immobilized with respect to the drum whenever said valve is closed, thus relatively immobilizing the prosthetic upper and lower limb portions; biased, reciprocal cam-actuated means operably connected to the valve for operating the same; and selectively operable means for reciprocating said cam-actuated means.

14. A prosthetic joint adapted to pivotally join two prosthetic limb portions together and adapted to be controllably restrained against relative pivotal movement in any selected position within its operative range, comprising; a base adapted to be attached to one of said prosthetic limb portions and provided with ears having laterally alined ports; a shaft carried by said ears and connected to said one of said limb portions; a hollow liquid-containing drum mounted on the other of said limb portions with the shaft rotatably passing through the center thereof; a ported plug closing one side of said drum to form an arcuate drum chamber; a valve mounted in said ported plug adapted to allow the passage of liquid from opposite ends of said annular drum chamber through said ported plug when open and to prevent the passage of said liquid therethrough when closed; a vane in said hollow drum and operably connected to said shaft, said vane dividing the arcuate chamber into variable volume chambers; and selectively operable means for controlling the position of said valve.

15. A prosthetic joint adapted to pivotally join prosthetic limb members together comprising: a shaft carried by one of said limb members in non rotatable relation thereto and a hollow drum mounted on the other of said limb members and rotatable therewith around the shaft, said drum encircling said shaft; a fixed partition within the drum on one side of the shaft, said partition forming an arcuate, liquid-receiving drum chamber around said shaft; a, valved conduit through said partition connecting the ends of said arcuate drum chamber; and a rotor vane carried by the shaft within the drum and in sliding contact with the walls thereof, said rotor vane dividing the arcuate drum chamber into two variable volume chambers connected by said valved conduit, whereby relative pivotal movement of said limb members may be restrained by adjustment of a valve in said valved conduit.

16. A prosthetic joint for pivotally joining two prosthetic limb portions and adapted to be controllably restrained against relative pivotal movement, comprising: a base attached to one limb portion; a hollow, liquid-carrying drum mounted on the other of said limb portions; a shaft extending through the center of the drum for rotation relative to said drum; an arm carried by the shaft ior attachment to said one of said limb portions; a xed segmental partition Within said drum forming an arcuate drum chamber around the shaft; a conduit through said partition connecting the opposite ends of said drum chamber; a rotary valve in said partition arranged to open and close said conduit; a rotor vane connected to the Shaft and extending radially in the arcuate drum chamber to the outer wall thereof and dividing said chamber into two Variable volume chambers separated by said vane and partition; and means for controlling the positi-on of said rotary valve.

ORVIN s. JOHNSON. j Y

(References on following page) References Cited in the le of this patent UNITED STATES PATENTS Number Name Date Cotty Dec. 9, 1862 Webb Aug. 12, 1919 Loth Sept. 13, 1921 Habermann June 27, 1922 Stewart Oct. 3, 1939 McCann July 16, 1940 Stewart Aug. 9, 1949 18 FOREIGN PATENTS Number Country Date 316,515 Germany Dec. 2, 1919 523,329 France Apr. 19, 1921 5 530,623 France oct. e, 1921 530,887 France Oct. 12, 1921 OTHER REFERENCES Terminal Research Reports on Articial Limbs 10 by Committe on Articial Limbs, National Re search Council. A copy was received in Div. 55 of the Patent Oce on November 13, 1947. Pages 27 and 28.

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