Action of the Subtalar and Ankle-Joint Complex During the Stance Phase of Walking

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1964;46:361-464. J Bone Joint Surg Am.D. G. WRIGHT, S. M. DESAI and W. H. HENDERSON

Phase of WalkingAction of the Subtalar and Ankle-Joint Complex During the Stance

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Action of the Subtalar and Ankle-Joint Complex

During the Stance Phase of Walking

BY D. G. WRIGHT, M.D.f, s. �i. DESAI, M.E4, AND

W. H. HENI)ERSON, B.54, SAN FRANCISCO, CALIFORNIA

From tile Biomechanics Laboratory, University of California, San Francisco and Berkeley

Tim this study, a continuation of previous work on human locomotion 2,3,4,5,9�

the nmotioim between shoe and leg during the staimce phase of walking was analyzed

jIm terimms of rotation about the axes of the subtalar and ankle joints.

Location of Axes

It is generally believed that motion of the subtalar and ankle joints closely

appioximates that of a simple hinge � and that the joints should therefore have

simple axes of motion. The location of these axes has occupied many investigators.

In geimeral, it may be said that the axes are located as follows: The ankle axis passes

traimsversely through the body of the talus ; and the subtalar axis is located distal

to time talus and runs obliquely downward, outward, and backward.

Hicks did a comprehensive study of this subject (Fig. 1). He found two axes

of ankle nmotion, one in dorsiflexion and one in plantar flexion. They will be referred

to here as a single axis, the ankle axis. Hicks also found three axes immediately

distal to time talus: time talocalcaneonavicular, the oblique mid-tarsal, aimd time antero-

posterioi nmid-tarsal (Fig. 1). The first two have imearly ideimtical actions. Hicks re-

ferred to timem together as time oblique hinge ; they will be referred to imere as time

subtalar axis. The other axes described by Hicks, includiimg the aimtei-oposterior

mid-tai-sal, ai-e co�mcerned only with motion of the fore part on the hind part of the

foot mmd will not be discussed here. In all the studies to be described here, a firm shoe

was woiii by the subject and rotation about timese other axes was considered to be

pi-actically absent. Other investigators are in agreement with Hicks’ locatirnm of

t.imese axes 1.8 � is important to note (Fig. 1) that the ankle axis lies in a Imorizontal

plamme aimd is externally rotated in this plane so that it is oblique to the frontal plane

of time foot. rfhe obliquely located subt.alar axis usually forms aim angle of 10 to IS

degrees witim time sagittal plaime and 45 degrees witim the horizoimtal plane of the foot 8#{149}

Terminology

Coimsiderable confusioim exists in the terminology used to describe IflovelflentS

of the foot and its joints. Often there is inadequate distinction nmade betweeim the

two. In this paper, we slmall use two different sets of terms to distinguish foot move-

nmeimts from joint movenmemits.

Time traditional terms in anatonmical writing, do�-siflexion-plaiitai- flexioii, in-

version-eversion, and abduction-adductioim, are used to describe movemeimts of

time foot relative to time sagittal, frontal, and transverse planes. Stated in a different

Immalmner, immovement about a hypothetical axis passing transversely through the foot

would be doi-siflexion-plantar flexion, about a vertical axis would be abduction-

* TE’iiis inVestigation was supported by Veteraims Administration Contract VIOO5M-2075

lI1(l Faster Seal I�)uIl(1ation (1r:ttit VJ-29.

t 2313 \\(�5t Marston 1.)rive, Anchorage, Alaska.:1:Biome(-hanics LaI.)orat.ory, University of California \Iedical Center, 8:111 }rancisco, Cali-

fornia 94122.

VOL. 46-A, NO. 2. MARCH 1964 361

Orientation

Scale� 10cm.

4 T.

,d.a.

362 D. G. WRIGHT, S. M. DESAI, AND W. H. HENDERSON

THE JOURNAL OF BONE AND JOINT SURGERY

adduction, and about a longitudinal axis would be inversion-eversion. As mentioned

in the previous section, however, the observed axes of motion in the foot do not

coincide with the hypothetical ones ; movement about the ankle axis combines

dorsiflexion-plantar flexion with a slight degree of abduction-adduction, and subtalar

motion combines dorsiflexion-abduction-eversion in one direction and plantar

flexion-adduction-inversion in the other. These subtalar motions have been called

pronation and supination, respectively, in traditional terms.

We have chosen to speak of motion about the joint axes as either negative or

positive rotation. Negative rotation appears as a downward deflection on the

patterns of rotation recorded in this study ; at the ankle joint this negative rotation

represents plantar flexion-adduction and at the subtalar joint it represents dorsi-

fiexion-abduction-eversion. When it is necessary to describe the amount of rotation

that has occurred about an axis at a given instant in the walking cycle, it will be

done in terms of angular rotation relative to a neutral position which will be dis-

cussed later.

Fm. 1

Location of joint axes. The axes of all the foot joints (except those of the middle three rays)adapted from roentgenograms of the experimental foot. Foot in basic position of relaxed flatstanding, the ankle being in a position of moderate extension, the talocalcaneonavicular and mid-tarsal joints at or near full pronation, the first ray at full extension-supination, and the fifth raynear to full flexion-supination. d.a., dorsiflexion ankle axis; p.a., plantar flexion ankle axis; ten.,talocalcaneonavicular axis; o.m.t., oblique mid-tarsal axis; a.p.m.t., anteroposterior mid-tarsalaxis; lr., first ray axis; 5r., fifth ray axis. (Reprinted from The Mechanics of the Foot: I. TheJoints by J. H. Hicks. J. Anat., 87 : 350, 1953.)

x

V

(a) (b)

ACTION OF THE SUBTALAII AND ANKLE-JOINT COMPLEX 31;::;

VOL. 46-A, NO. 2, MARCh 1964

V

Y

PLANE OF MOTIONPERPENDIGUL�R TO X-AXIS

PLANE OF MOTION

PERPENDICULAR TO NEITHER AXIS

TOP VIEW

V

SI DE VIEW

FIG. 2

l)iagranm of uni��ersal joint.


Action of Axes

The subtalar and ankle-joint complex permits flexion of the foot on the leg.

The manner in which this is accomplished can be visualized through the analogy

of a universal joint. Figure 2 shows such a joint, with its two axes, x and y. Through

various amounts of rotation about these axes, flexion of one member of the joint on

the other may be accomplished in any vertical plane.

It can be seen (Fig. 2,a) that rotation about one axis (x) to the exclusion of the

other (y) can be accomplished only if the plane of motion is perpendicular to the

axis about which rotation occurs (x) ; or, stated differently, no rotation about the

axis (y) which lies within the plane of motion. When a rotation is imposed on the

system in a plane that is perpendicular to neither axis, rotation will take place iim

part about each axis (Fig. 2,b) . The amount of rotation occurring about eaclm axis is

a function of how closely that axis approximates the perpendicular to the plane of

motion. This analogy to the ankle-subtalar joint is an oversimplification but illus-

trates the mechanical principles involved.

When the analogy is applied to the shoe and leg relationships, the shoe, or foot,

becomes one member of the joint; the leg, the other; and the subtalar and ankle-

joint system, the interposed axes. In flexion of the leg on the shoe, the plane of the

motion will determine how much of the motion occurs as subtalar rotation and how

much as ankle rotation. In ordinary walking, the ankle axis lies nearly perpendicular

to the plane of flexion of the leg on the shoe, and rotation around timis axis accounts

for most of the walking motion. It was shown 1.7,8� however, that the ankle axis is

not perfectly perpendicular to the long axis of the foot or to the plane of motion;

therefore, a portion of the motion must occur as rotation around the subtalar axis.

Two further examples of the application of this principle to the actioim of the

subtalar and ankle-joint complex should be noted. First, during stance phase the

tibia rotates about its long axis, but the foot is not permitted to adduct or abduct

because it is fixed to the floor by body weight. Therefore, this tibial rotation must

be resolved at the subtalar or ankle axis. The ankle axis lies within the Imorizontal

plane of this motion. Thus, this motion of the tibia cannot be resolved about the

ankle axis and takes place wholly about the axis of the subtalar joiimt ; therefore,

interimal rotation of the tibia acts through the subtalar axis to produce pronation

which is dorsiflexion-abduction-eversion of the foot relative to the leg.

The other example is active plantar flexion. The triceps surae, in plantar flexing

the foot, rotates the foot in a plane perpendicular to the ankle-joint axis. This

rotation may be entirely accomplished at the ankle joint, and the integrity of the

foot as a lever is preserved by other factors which provide immobilization of the

subtalar joint.

Forces and Displacements

Figure 3 shows some of the forces and displacements that are associated with

function of the subtalar and ankle joints during walking. This information is

derived from previous locomotion studies done at the University of California 2,9�

Some of these findings may be summarized briefly here:

Stance phase occupies the first 60 per cent of the walking cycle. During timis

phase the tibia, as it moves forward over the foot, remains in a parasagittal plane,

not deviating medially or laterally (Fig. 3,B and C). From 0 to 15 per cent of the

cycle, the foot plantar flexes on the leg and is placed flat on the ground (Fig. 3,C);

the anterior tibial muscles act to decelerate this motion (Fig. 3,F) ; the tibia rotates

internally (Fig. 3,A) ; and weight is gradually applied to the foot until by the end of

this period the foot is supporting the entire body weight (Fig. 3, D). At 15 per cent


t

4

©

40 60

PER CENT OF WALKING CYCLE

VOl.. 46-A, NO. 2, MARCh

ACTION OF TILE SUBTALAIt ANI) ANKLE-JOINT COMPLEX 365

of the cycle timere is a chaimge in direction in most gait patterns, and between 15

amI(l 50 pei- cent of the cycle time foot dorsiflexes on time leg (Fig. 3,C) ; the tibia i-otates

exterimally and toi-que is developed i)etween time foot amid time floor (Fig. 3,E). The

postei-ior nmuscles of time leg simow progressively greatei activity throughout the

latter half of timis pei-iod, umitil nmaxilmmiiimi activity is i-cached at 45 per cemmt of the

cycle (Fig. 3,G).

Dorsiflexiomi of time foot ott the leg is then replaced by plantar flexion and

immaxiimmunm vertical force is developed (l�ig. 3,C and D). 1)uring the end of the stance

phase, wheit time foot is plantar flexing sharply, time vei-tical force and immuscie activity

fall oil mmmai’kedly (I�ig. 3,C, I), Ii’, aII(I G).

:c�c. #{149}EL�PER CENT OF WALKING CYCLE

#{174} 20 40 60 80 00

TIBIALROTATION-TOPVIEW �

XI-

c.�0

FIG. 3

Forces aiid displacenmetmts during walking.

1964

4

FIG. 4

Mechanical analog of subtalar and ankle-joint system.


THE JOURNAL OF BONE ANI) JOINT SURGERY

Testing Equipment

Methods

The testing unit used was the mechanical analog of the subtalar and aimkle-

joint complex developed by the orthotics research group and described imma previous

report 6� Briefly, timis device duplicates externally time internal-joint system of time

ankle and subtalar joiimts. When time unit is adjusted so timat the axes of time nmechaimi-

cal and anatomical joints are coiimcident, the wearer feels no interferelmce with Imis

normal motions. 1’or this study, the unit was attached to the leg witlm a plaster cast

( Fig. 4) and to the simoe with a stirrup. Potentionmeters ms-ei-e incorporated in the

mechanical axes so that rotations about both axes could be recorded individually

and simultaneously. The testing unit is shown on a subject in Figure 5.

Contacts made of conductive rubber were placed at the heel and toe of time shoe

worn by time subject. Wires from the potentiometers aimd fronm the coimtacts were

carried by aim overhead track to the recording equipnment.

Walkways were covered with copper sheeting to complete time circuits for the

heel amid toe contacts and were long enough to permit six or seven consecutive steps.

For uphill, downhill, and sidehill walking, an adjustable copper-covered ramp was

constructed wimicim allowed for three consecutive steps.

Im(;. 5

lestitig uiiit imi 1)1�(e oIl SUII)j(’(t.

ACTION OF THE SUBTALAR AN1) ANKLE-JOINT COMPLEX 367

\.OL,. 46-A. NO. 2. MARC!! 1964

Recording of lValking Patterns

The electronic systeni ‘K continuously recoided the position of time subtalar

almd ankle joints during the walking cycle in the form of three tracings. Typical

traciimgs are simowim in Ii�igure 6. The top line simows rotation about time ankle

axis. Aim upward deflectioim occurs with positive rotation (dorsiflexion-abduc-

tion) ; a dowimward deflection, with negative rotation (plaimtar flexion-adductioim).

The nmiddle line represents rotation about time subtalar axis. Here a�m upward de-

flection occurs with positive rotation (supination) , a downward deflection with

negative rotation (pronation). The bottom liime shows time imeel contact nmade and

time toe contact broken at the beginning ammd cud, respectively, of stance plmase.

This imeel-aimd-toe record makes it possible to orieimt time iotatioimal patterns in

relation to time walkiimg cycle. Two complete cycles are simowim iii the figure.

All ti-aeings progress fi-oimm left to right. A standard calil)I-atiomi was used so

timat omme ceimtimeter of vertical deflection represemmt.s 8 degrees of rotation. Time paper

speed was kept constalmt imm all ti-acings so that temi centimeters along time imorizoimtal

scale repieseimts one second of elapsed time. Tracings in every case are of time left

foot and leg.

Wimen time tracings obtained from each trip along the walkway (five consecutive

steps) were superimposed, they showed a imigh degree of similarity (Fig. 7). Results

from the first step were generally discarded since the normal walkilmg speed imad not

yet been attained and time traciimgs of time first step along time imorizoimtal axis varied

fm-oimm time others. The tracings presented here as illustrations are either average

curves drawn from the means of the superimposed recordimmgs or typical tm-acings.

* The sensing device was a \Viieatstone bridge. ‘flie l)otemltionm(!ter in time unit fornmed the

varial)le elenmemit. iim the bridge circuit. Initial 1)alance (zero output) could be estal)lished at any

1)05iti�11 of the suhtalar or ankle joint. To acimieve balance, a I)oterltionmeter was adjusted iii serieswith the transducer. Calibration was effected by selecting tue appropriate resistance inserted inseries with the op�)osing leg. The voltage changes in the circuit were recorded by an Olimier 1)vno-graph, MO(l(l 504 it.

FIG. 6

Typical record of ankle and subtalar rotations.

negative

4

STANCE PHASE

FIG. 7



A typical section of the records obtained is shown in Figure 6 ; Figure 7 simows a

series of these tracings superimposed. The graphic average or best line of the lines in

Figure 7 is represented in Figure 8.

The neutral position was the position of the ankle and subtalar joint wimen the

subject was standing relaxed with the knees fully extended, the arms at the sides,

feet six inches apart, and a comfortable amount of toeing-out. This position was

taken as zero degree of rotation for both joints and was also the position cimosen

for balancing the electronic recording equipment at zero. This neuti-al position is

shown by the horizontal straight line passing through all tracings.

tpositive

ANKLEROTAT ION

tpositive

Su BTALARROTATION

negative

‘I

Superinmposed records of ankle and subtalar rotations (five consecutive steps).

The positive rotation that occurred at the subtalar joint during staimce phase

was measured from its onset to the time at which the ankle joint began imegative

rotation for the second time (at heel rise). The ankle-joint motion, also positive

rotation, was measured over the same period.

Measurement of Toeing-out

1\’Ieasurement of the amount of toeing-out (abduction) during walking was

(‘ormdit ions

First nornmal

run 8.3 6.6 7.8 6.2 8.6 6.9

Second normal

run 8.2 6.6 7.4 5.9 7.4 5.9

No arnm swing 7.8 6.2 7.9 6.3 7.6 6.1

Exaggeratedarnm swirmg 9.4 7.5 9.0 7.0 7.8 6.2

Toeing-out 11.8 9.5 13.3 10,6 Not done

Toeing-in 3.1 2.5 4.4 3.5 Not done

Long stride Not done 8.6 6.9 8.5 6.9

Short stride Not done 7.4 5.9 7.7 6.2

TABLE II

EFFECT OF CADENCE ON 1)EGREES OF ROTATION

(Subject 1)GW)

Subtalar Axis Ankle Axis Stance Phase Cadence(Degrees ( Degrees (Duration (Cycles

of Rotation) of Rotation) in Seconds) per Minute)

Nornmal gait:

average values forseventeemi steps 6 (5.7) 17 (16.8) .80 48

Ra1)id gait:

average values for

eleven steps 6 (6.4) 17 (16.8) .67 56

Slow gait:

average values fortwelvesteps 6(6.1) 18(18.4) .96 41

ACTION OF THE SUBTALAR ANI) ANKLE-JOINT COMPLEX 369

VOL. 4k-A, NO. 2. MARCH 1964

made possible by ink-marking devices fixed to the heel and toe of the shoe (Fig. 5).

The aimgie formed on the walkway by the intersection of a line connecting these

two points with a line along the center of the walkway was measured, and the two

poiimts on the shoe were then related to the long axis of the foot by means of a

roentgeimogram made through the shoe. The true amount of toeing-out was calcu-

lat.ed by applying the appropriate correction to the angle measured from the ink

marks. Time long axis of the foot was considered to bisect the tuber calcanei and

pass between the heads of the first and second metatarsals 8#{149}

TABLE I

FACTORS AFFECTING AMOUNT OF SUBTALAR ROTATION

1)egrees of Rotation(Average Measurements of 20 to 30 Consecutive Steps)

Run #1 Run #2 Run #34/8/60 4/12/60 4/15/60

(Millimeters) ( Degrees) (Millimeters) ( Degrees) (Millimeters) ( Degrees)

Measurement of Axes on Testing Unit

Time axes as described by Hicks and others were assumed to be correct and the

unit was so adjusted. Further adjustments were then made ummtil time subject had

freedom of motion about time subtalar and ankle axes. In order to determine the

fiimal locatioim assumed by the axes, two points were chosen on time unit which lay

aloimg each axis and could be measured wimile time unit was on the subject. I\Ieasure-

ments ��‘ere made in three dimensions. While the subject stood on a piece of ruled

paper, a perpendicular was dropped to the paper from each point on the unit.

Time poimmts so located on the paper established two dimensions. The third dimension

was obtaiimed by measuring the length of each perpendicular by means of a surface

gauge. Projections of these points (and the axes which they defined) were plotted

HEEL CONTACT TOE OFF HEEL CONTACT

T�STANCE PHASE � -�. �FOOT IMMOBILE+

0 100

HEEL

ANKLEROTATION

�FOOT IMMOBILE



in two plaimes, time horizontal and the vertical. In this way, the inclination of timese

axes relative to the floor and to the long axis of the foot could be determined.

Experimental Studies

Effect of Various Factors on Subtalar Rotation

The objective of the first study was to determine how much subtalar rotation

takes place during normal walking and what variables in walking affect it. For this

investigation, the testing unit was adjusted to record only subtalar rotatioim.

ANKLEROTATiON �

SUBTALARROTATION �

20 40 60 80

PER GENT OF WALKING CYCLE

FIG. 8

Aimkle mmd subtalar rotations during normal walking (subject DGW),

SUBTALARROTATION

FIG. 9

Ankle and subtalar rotations during walking with toeing-out (subject DGW).

.iCTION OF THE SUBTALAII ANI) ANKLE-JOINT COMPLEX 371

HEELCONTA�T I TOEOFF

RO�AT�gN� � � I’

� +FOOT IMMOBILE

SUBTALAR � � ______

FIG. 10

Aiikle 1.11(1 sul)talar rotations (luring walking with toeing-in (subject 1)(�\V).

It was anticipated that increasiimg the rotation of time tibia about its loimg

axis would immcrease time amoummt of subtalar rotatioim through the mechanism de-

scl’ibe(l previously. To test this concept, walking was studied witim increased arm

swing and with leimgtimened stride. Both of these variables should increase rotation

of time tibia about its loimg axis during walkiimg. Lengtlmeimed stride should also produce

greater ankle motiomm.

Toenmg-imm and tceimmg-out were also studied in order to observe the effect of

cimamiges iii placement of time foot relative to time plaime of progressiomm.

Tai)le I gives time results of timis study. Readings for normal walking were

obtained at the i)eginnilmg and cud of each run and the same subject was used for

all I�tIflS. Time data in Table I are averages of measurements of twenty to thirty

commsecutive steps ummder that particular condition on that particular day. All

nmeasui-emmments weie nmade during the positive-rotation component of stance phase.

It cami be seen from Table I timat time normal amount of positive rotation during

staimce phase was of time order of 5.9 to 6.9 degrees and timat time only deviations of

iiote were pi-oduced by toeing-in aimd toeiimg-out. The explanation for the lack of

effect of time other variables probably lies in time fact timat their effect depends on

the axial motation of the tibia being transmitted through time subtalar axis to the

foot, as discusse(1 previously. However, during niost of stance phase-time phase

dut-itig w-hich the rotations were measured-time shoe with its relatively flat sole

was fixed to time floor by body weight and very little inotioim was permitted between

time shoe and time floor. The effect of toeing-in and toeing-out, however, was not to

cause nmotion of time shoe relative to the floor i)ut ratimer to alter the position of the

foot, and imence of the joint axes, relative to the plane of progiession.

If w-e return to the analogy of the universal joint (Fig. 2), we see that three

conditions are imecessary for this principle to apply to the ankle and subtalar axis

systeni:

1. One menmber of the system must be immobile, aimd so we must consider only

timat portion of stance phase during which the foot is flat on the ground;

2. We must know the plane in which the otlmer member is moving and so must

vor.. 46-A, NO. 2, MARCH 1964


accept the evidence from Figure 3,B that the tibia moves in a plane parallel to the

plane of progression of the body as a whole;

3. We must assume that, during the time under consideration, the only rotation

imposed on the system is that imposed by the flexing of one member on the other.

Effect of Various Positions of the Axis System

If the conclusions of the preceding section are correct, time axis system should

behave in a predictable manner when placed in various positions. Thus, the more

nearly time ankle axis is perpendicular to the plane of progression, the greater should

HEELCONTACT TOEOFF HEELCONTACT

, �.

ANKLE � _ ,�::::::::::::::b�_��ROTATION I

I � STANCE PHASE� P

-40H� +FOOT IMMOBILEU#{216}�

I� �;

PER CENT OF WALKING CYCLE

FIG. 11

Ankle and subtalar rotations during normal walking (subject JM).

be its role in the rotation which is imposed by flexion of time tibia. Similarly, immotion

about the axis of time subtalar joint should increase as the axis of the aimkle joint

is positioned farther from the perpendicular. The second study attempted to con-

firm these assumptions by obtaining patterns of subtalar and ankle-joint rotation

for various positions of their axes relative to the plane of progression.

1 . Toeing-in and Toeing-out

Figures 8, 9, and 10 show the mean or best curves plotted from superimposed

patteins of consecutive steps in normal, toeing-out, and toeing-in walkiimg. All

patterns were taken from the same subject on the same day. It was assumed timat

the foot was flat mm the ground during the time between the vei-tical markings

(broken lines on the tracings) and that, duriimg this time, the axis system beimaved

ili a predictable manner as indicated previously. We have seen that the axis of time

ankle joiimt iii nornial walking lies in time horizoimtal plane amid is externally rotated

with respect to the frontal plane of the foot. One would, therefore, expect that, as time

foot position was shifted from toeing-in to normal to toeing-out, time ankle axis

would be positioned progressively farther from the pei-peimdicular to the plane of

progression, amid rotation about the ankle axis would decrease pi-ogressively, while

rotation about the subtalar axis would increase progressively.

THE JOURNAL 01’ BONE AND JOINT SURGERY

HEEL CONTACT‘r I

TOE OFF

ANKLEROTAT ION

Su BTA LARROTATION

100 +FOOT IMMOBILE�

‘V

ANKLEROTATION

I�FOOT IMMOBILE+�!

ROTATION

FIG. 13

Jim Figum’es 8 timrougim 10 it can be seen for subject DGW that rotation about time

axis of the subtalai joint did increase as expected. Time pattern of rotation about

time axis of time aimkle jonmt also changed, but the amount of rotation about this axis

during stance phase was essentially unchanged.

VOL. 46-A, NO. 2, MARCh 1964

ACTION OF THE SUBTALAII AN!) ANKLE-JOINT COMPLEX

I if I I’

FIG. 12

Ankle and suhtaiar rotations (luring walking with toeing-out (subject J�\I).

Armkle 911(1 slli)taltlr rotations during walking with toeing-in (subject J \I).

373

374 D. G. WRIGHT, 5. M. DESAI, AND W. H. HENDERSON

This study was repeated with a second subject (JM) who imad an habitual

toeing-out gait. His patterns for these three conditions are shown in Figures 11

through 13. Again, the subtalar motion progressively increased from toeing-iim to

toeing-out and the ankle patterns showed a change in form but not in degree of

rotation. In an attempt to quantitate this increase in subtalar rotation, a study

20 -

(1)wwa:

Lii I6 -

2 S

0 5 5

�I2-

I-0 S

a: S S

�8- .5

_J S

< ..I- .5

cx�

C’)

0 � I I I 1 I I I 1 I I I 1 1�_�_I

0 4 8 12 I6 20 24 28

TOE-OUT DURING WALKING, DEGREES

FIG. 14

Effect on subtalar rotation of walking with increased toeing-out (subject DGW).

S S

20 -

U) 5 5w .5 5Lii #{149} Sa:I6- S

� S S

c� -

S S S

z 555�I2-.. S

I-

I-0a: 8-

w-I

z44

0 � I I I I I I I 1 1 1 I

0 4 8 12 16 20 24 28

TOE-OUT DURING WALKING, DEGREES

FIG. 15

Effect on ankle rotation of walking with increased toeing-out (subject DUW).


HEEL CONTACT TOE OFF

Ib) EVERTED (HIGHER) FOOT

F’m�. 1#{128})


R�A�N

�. 4�FOOT IMMO8ILE-.#{216}�

J�L �

SUB�LAR

a) ASCENT OF SLOPE

FIG. 17

PIEELCOP4TACT � TOEOFF

vol.. 46-A, NO. 2, MARCH 1964

ACTION OF THE SUBTALAR AND ANKLE-JOINT COMPLEX 375

was made irm which time degree of toeing-out, measured for many steps, was plotted

agaiimst subtalar and ankle rotation. During this study, toeing-out was progressively

iimcreased by conscious effort. Subtalar rotations increased as anticipated but ankle

rotations remained essentially unchanged (Figs. 14 and 15).

�c

�


R��N

IO#{149}� .�FOOT IMMOB�LE-4

(a) INVERTED ILOWER) FOOT

Ankle 911(1 subtalar rotations during sidehull walking (subject l)G\V).

I/\� �2’ � � �_-�----��1 � �. � I

� �. I

.+

IO#{149} .�FOOT IMMOBILE -0.

b) DESCENT OF SLOPE

Ankle amid sul)talar rotations (Itiring slope walking (subject DG”IV).

2. Sidehill Walking

This coimditiomm requires that time uphill foot be placed in an attitude of eversion

and the downimill foot in inversion iii stance pimase. Eversion of the foot, acting

tlmrough time subtalar joint, results in internal rotatioim of the tibia amid inversion re-

stilts in external rotation. We would, them-efore, expect that, during walking with

time foot everted, time amikle axis would be rotated into a position more nearly per-

pemidicular to time plane of progm-essiomi and that the opposite would occur with the

foot in inversiomi. The rotation about time ankle axis should 1)e greatest in eversion

�O_ .4-FOOT IMMOBILE -+


and least in inversion, whereas motion at the subtalar joint should be greatest in

inversion and least in eversion. (The assumption is made hem-c that the degree of

toeing-in and of toeing-out was consistent duriimg both situations. Altimougim this

factor was not measured, no subjective difference was noted.)

Figure 16 shows patterns recorded during horizontal walking aloimg time side of

a 9.5-degree slope. With eversion of the foot, ankle motion was greatly increased,

whereas subtalar motion was only slightly altered.

HEELCONTACT TOEOFF HEELCONTACT TOEOFF

�

�

(CI ASCENT OF SLOPE Ib) DESCENT OF SLOPE

FIG. 18

Ankle and subtalar rotations during slope walking (subject DGW).

TOECONTACT , IIEELOFF TOECONTACT IIEELOFF

R��N

IO#{149}� 4FOOT IMMOBILE��

=I� � ..�-__.__.________j__t�--

(0) SUBJECT DGW

FIG. 19

Ankle and subtalar rotations during backward walking.

3. Uphill and Downhill 1Valking

The subjects were studied walking up and down a ramp with a 15-degree iii-

dine. Each foot, during stance phase, was in dorsiflexion ascending and in plantar

flexion descending the slope. Since the orientation of both joint axes with respect to

the plane of progression was essentially unchanged in this situation, the net rota-

tional changes about the axes were expected to be the same going up and going

down. However, as shown in Figures 17 arid 18, the rotations about the aimkle axis

were much greater during descent on the ramp, presumably because of inactivity

of the triceps surae ; this factor will be considered in the iiext section. Subject J\i

showed increased subtalar and ankle motion, while subject DGW did not.

4. Backward Walking

It was anticipated that backward walking would produce a revem-sal of the

Ib) SUBJECT JM


ANKLEROTATION

_4. L10 � 4FOOT IMMOBILE+

SUBTALAR

ROTATION

� I

HEEL OFF

--.H� IIO#{149}� 14 FOOT IMMOBILE �I

�+�L �

ACTION OF THE SUBTALAR AND ANKLE-JOINT COMPLEX 377

VOL. 46-A, NO. 2. MARCH 1964

imormal displacements. In Figure 19, displacement patterns are presented for the two

subjects walking backward with their normal patterns obtained on the same day

shown reversed in broken lines. It can be seen that the backward-walking patterns

were very similar to the reversed normal patterns except for a much greater range

of ankle motion. This effect, again, was presumably associated with elimination of

time action of the triceps surae.

Effect of Action of the Triceps Surac

i\Iaxinmunm ankle motion was produced by backward walking, downhmill walking,

amid also by eversion while walking. In each of timese commditions, the action of the

triceps surae was decreased or eliminated, although the mechanism of this decrease

during eversioim is not clear.

In order to confirm the idea that this pattern was indeed associated with

inactivity of time triceps surae in producing heel rise, a subject (WHH) with paralysis

ANKLEROTATION

SUBTALAR _________ __________________________ROTATION �N-. � ]-� - -----�---r-- - -

Fm;. 20

Ankle 9.11(1 subtalar rotations iim I)aralytic gait (subject \VHH).

of time leg was studied. Time only functional muscle in the leg was a weak tibialis

anterior. The ankle pattern here (Fig. 20) showed time same maximum excursion

and time same nearly linear development of that excursion thmat were seen in the

pattermms just mentioimed.

It must be realized that time pattern of knee motion (and therefore of tibia!

displacemeimt and of ankle motion) was altered in this subject and may also have

been altered in backward walking, ramp walking, and sidehill walking. The most

important associated finding imere was the effect of inactivity of the triceps surae

jim producing heel rise, but altered rotational patterns of the other joints may also

have aim important effect on time amount of ankle-joint rotation.

Effect of Tarious Cadences

Time anmoumit of rotation was compared for rapid, nornial, and slow gait. No

siglmificalmt differences w’ere found (Table II).

S4thlalar and .1 nkle Rotation During Normal Level Walking

Fimially, the raimge of motion in time subtalar and ankle joints was nmeasured

duiiimg level walking. The informatiomm gained iim previous studies was used to deter-

mine wimich factors should affect these measurements. Time degree of toeing-out

assunmed with eacim step was nmeasured and time location of time axes on time unit was

recorded after eaclm ruim.

FIG. 21

Recordings showing early heel rise (subject DGW).

378 D. G. WRIGHT, 5. M. DESA!, AND W. H. HENDERSON


Values for certain steps were discarded as not being those of normal walking.

For example, when the subject lost balance, there was a sharp deflection in the

subtalar pattern. Also not considered were steps in which there was premature heel

rise as indicated by a negative deflection in the ankle patterns during time latter

half of stance phase. Such steps were not taken into account because they produced

a reduction in the amount of subtalar rotation. Figure 21 shows two consecutive

steps with premature heel rise taking place in the first.

In Table III, measurements are listed of the amount of rotation about the

subtalar and ankle axes that occurred in stance phase during normal level walking.

The amount of toeing-out for subject DGW had been established as between

5 and 6 degrees on several previous occasions. On the second day of this study, his

average toeing-out was, after correction, 5.5 degrees to the true longitudinal axis

of the foot. The axis location assumed in adjusting the unit was similar on the two

days. The average subtalar rotation was 6 degrees and the average ankle rotation

was 14 degrees on both days.

Discussion

Location of Axes

The testing unit used in these studies can best be described as a detector

system, fixed to the foot and leg and adjusted to record rotation around certain

axes. The unit was first adjusted to the positions of the ankle and subtalar axes

described in previous anatomical studies 1,7,8#{149}Then, to allow for individual differ-

ences, further adjustments were made until the subject had freedom of motion.

The objection may be made that the unit is less adaptable than the foot and hence

that the unit rather than the foot dictates the motions occurring during walking

and that lack of feeling of restriction by the wearer could be simply a manifestation

of the adaptability of the foot. However, in view of the careful anatomical studies

to which the original adjustment conformed and the final individual adjustment

made to allow freedom of movement, it is believed that the subtalar and ankle

motions allowed by the unit were not significantly different from those that would

have occurred in the unencumbered state.

Ankle and Subtalar Rotations in Relation to Other Events of the Walking Cycle

As the foot approaches heel strike, positive rotation takes place (Figs. 8 and

ACTION OF THE SUBTALAII AND ANKLE-JOINT COMPLEX 379

TABLE III

TAILE 3 - MEASUREMENTS OP ROTATI�W4 ABOUT SUBTALkR MID AIIKI.E AXES DURING NORMAL LEVEL WALKINGSubject 11GW

Millimeters of v,rtical deflection; 1 a. � 0.8#{176}

TIRSTD)�.T SECOND DAY

�2

AX IS LOCATION AX IS LOCATION

Ankle: horizontal, 102#{176}with long &xi. Ankle: horizontal, 990 wttm� long axis0 0 0 o

Subtalar: 48 with floor; 12 with long axis Subtalar: 38 with floor; 12 with long axis

ANKLE RIYEATION SUBTALAR ROTATION ANKLE ROTATION SIIBTALAR ROTATION

21 S 14 519 4 11 819 4 13 11

17 6 18 7

18 6 19 10

15 7 17 315 8 21 9

14 5 15 7

18 S 19 9

19 7 21 7

� � � � ANKLE ROTATION SIBTALAR ROTATION TOE OUT

17 6 17 7 14 10 13

20 9 20 9 15 9 11

21 6 20 7 13 7 14

17 7 14 N 15 10 1218 11 18 10 15 5 10

18 6 1� 9 20 8 12

18 8 16 7 16 8 13

16 9 18 5 20 5 10

17 8 17 9 11, 4 10

19 6 16 10 18 T 13

17 4 19 7 18 7 13

15 9 19 10 12 5 7

18 5 20 10 14 11 10

17 7 18 10 14 4 9

15 7 17 6 18 7 Il

17 7 17 5 15 9 15

� � � � Average 15.8 (12.6#{176}) :‘ 3 (5.8#{176}) 11.5#{176}

18 7 15 8

18 8 17 8

19 6 13 818 8 14 8

16 9 16 7

17 10 19 6

Is 6 20 820 13 16 5

18 8 [6

A vera,c 18 1 (14.4#{176}) 7 1 (5 7#{176}) 21 7

Average 17.2 (13.8#{176}) 7 5 (6.0

AIICLE ROTATION: 14#{176}

AWLE ROTATION: 14SUBTALAR ROTATION: 6

SUBTALAR ROTATION: 6TOE OUT (corrected): 5.5

11). ‘[he pretibial nmuscles wimicim show increasiimg electrical activity during timis time

(1�ig. 3,F) are no doubt responsible for this motiolm. Immediately after heel strike,

there is a sharp negative rotatioim about both axes during time first 5 pei� cent of time

cycle (Fig. 8). This movement results in the foot beiimg placed flat on time floor with

the position of the aimkle 8 to 10 degrees past neutral aimd the position of time subtalar

joimmt 4 degiees past imeuti’al. During timis 5 per cent of time cycle, time pretibial

VOL. 46-A, NO. 2, MARCH 1964

380 D. G. WRIGHT, S. M. DESAI, AND \V. H. HENDERSON

muscles show their peak activity, their function being to decelerate this motion

and thus prevent a slap of the foot on the floor. The small deflection which next

occurs in both patterns is possibly a rebound effect produced by the elasticity of

the shoe. At about 10 per cent of the cycle, positive rotation begins at the ankle

joint. Our data are in accord with the curve of ankle motion obtained by photo-

graphic methods (Fig. 3,C). By the time 20 per cent of the cycle has been reached,

the ankle has rotated a few degrees past neutral. The full body weight is now beitmg

carried by the extremity (Fig. 3,D) and the opposite extremity is in swing pimase.

From 20 per cent to 50 per cent of the cycle, the body is moving forward over the

foot, which is immobilized on the ground by body weight (Fig. 3,D). During this

time, there is progressive positive rotation at both the ankle and the subtalar joint,

until at 50 per cent both patterns change direction. There is then sudden negative

rotation at the ankle joint, and rotation ceases at the subtalar joint. The posterior

muscles halt rotation at the ankle joint in a way analogous to that imi wimichm the

anterior muscles halt the plantar flexion of the foot early in stance phase. From

50 to 65 per cent of the cycle, negative rotation occurs at the ankle joint as the heel

is lifted from the ground, ending the period of immobilization of the foot. As would

be expected, the vertical force falls to zero during this period (Fig. 3,D). At 65 per

cent of the cycle, the toe leaves the ground, ending the stance phase. At timis poimmt,

the foot is in 6 to 8 degrees of negative rotation at the ankle joint and jim 4 to 6

degrees of negative rotation at the subtalar joint. During swing phase, the foot is

returned to neutral position.

One factor which has not yet been taken into account is the rotatiomi of time

tibia about its long axis. Figure 3,A is a curve representing this rotation drawn

from highly variable data 2,9#{149}In general, it may be said that during the first 15 per

cent of the cycle the tibia rotates internally, and during the remainder of time stance

phase it rotates externally. While the tibia rotates internally, there is negative

rotation at both the ankle and the subtalar joint ; and while the tibia rotates exter-

naliy, both joints show positive rotation. This action will be discussed again later.

Analogy of Universal Joint

As previously stated the ankle and subtalar joints act together to provide a

universal-joint type of linkage between the foot and the leg. As the foot dorsiflexes

on the leg in walking, it does so in a plane that is not perpendicular to the aimkle

axis, so that rotation is necessary about the subtalar as well as the ankle axis.

However, there is one feature of the action of the ankle and subtalar-joint

system which is not made apparent by the simplified analogy of the universal joint

(Fig. 2). In contrast to the axes of the universal joint, the ankle axis and the subtalar

axis do not intersect and are not mutually perpendicular. If a model of the system

is made, it can be seen that flexion of the leg with respect to the shoe not oimly

requires rotation about both axes but also requires rotation of the tibia about its

long axis. This theoretical tibia! rotation has been experimentally observed (Fig.

3,A).

The analogy of the universal joint was used to predict the action of the joint

system in each situation studied. Figures 8 through 13 show that the subtalar

motion is predictable during the segment of the stance phase in which the foot is

flat on the ground. Thus, progressing from toeing-in to normal to toeing-out walk-

ing, the subtalar axis becomes progressively closer to being perpendicular to the

plane of motion and as predicted shows progressively greater rotation.

It has been noted from the anatomical studies that the ankle axis is exterimally

rotated in the horizontal plane and hence is oblique to the frontal plane of the foot.

As a result, this axis is not perpendicular to the plane of motion eveim with no


ACTION OF THE SUI3TALAR ANI) ANKLE-JOINT COMPLEX 381

toeimig-out. It would be progressively farther from that perpendicular as the walking

position changed from toeing-ui to normal to toeing-out. The amount of ankle

rotatiomi, then, would be expected to become progressively less duriimg this sequence.

In 1’igures 8 through 13, it can be seen that the amount of ankle rotation was 12 to

14 degrees in all tracings, but that the pattern of ankle rotation changed. When

subtalar and ankle rotations were plotted against the degree of toeing-out, the

filmdimmgs were the same (Figs. 14 and 15) . Subtalar rotation increased as toeing-out

ilmcreaSed in an approximately linear manner, whereas ankle rotation was unaffected.

rfhmree explanations for this lack of effect on the ankle-joint rotations can be

suggested. First, the effect of toeing-out on the ankle joint may be too small to be

detected by our metimods. Second, the muscle effort required to maintain the

positiomms of toei�mg-out aimd toeing-in may have exerted a selective suppressive effect

oim ankle motion through the triceps surae. Third, with toeing-out, the movement

of time tibia may have deviated from the parasagittal plane and hence imot conformed

to time limitations of our analogy.

It is interestiimg that the pattern of ankle rotation for DGW in toeing-out was

sinmilar to the normal pattern for JM, who habitually walked toeing-out.

When the subjects walked along aim inclined surface with 9.5 degrees of eversion

of time uphill foot and 9.5 degrees of inversion of the downhill foot (Fig. 16), it was

expected that the resultant altered staimce-phase position of each foot would cause

loimgitudiimal rotation of the tibia through the action of the subtalar joint, which

would in turn change the orientation of the ankle joint with respect to the plane of

progression. Eversion of the foot should rotate the tibia internally bringing the

ankle axis more nearly perpendicular to the plane of progression and immversion

should do the opposite. In theory, therefore, the ankle-joint rotation should be

greater in eversion than in inversion. In our studies, ankle rotation was twice as

great in eversion. This difference was mcre than had been anticipated.

As imoted already the ankle pattern in eversion was similar in configum-ation

and degree to the patterns obtained when the triceps surae was known to be mac-

tive. Possibly, the triceps is inactive in the limb with the everted foot because this

foot (Fig. l6,b) was at the higher level on the incline and the correspondimmg ankle

and kmmee had to go through a greater range of motion on this side to achieve effective

simortening of the extremity and so prevent excessive vertical oscillation of the

body’s center of gravity. It must be concluded that this portion of the study would

have been better done with the feet at equal levels.

Time rotation of the tibia, produced by inverted amid everted foot positions,

must imave affected the knee joint as well as the ankle. Alteration of the rotational

amid displacement patterns of the femur, tibia, and knee may well have affected

ankle rotation as al ready suggested.

Time subtalar patterns in Figure 16 show the expected displacenment above and

below the neutral position produced by eversion and inversion during walking.

Timese patterns also show that slightly niore rotation occurred in inversion than in

eversioim. This is presumably the anticipated effect of placing the subtalar axis more

nearly perpeimdicular to the plane of moti.n.

Time patterns obtained for walking up and down a 15-degree incline (Figs. 17

amid 18) simow the effect of time triceps sum-ae on ankle rotation. In walking up the

ranmp, time foot was placed in an attitude of slight positive rotation about the ankle

axis at time onset of the stance phase amid this positive rotation immcreased by only 8

to 10 degrees as stance phase progressed. Walking dowim the ranip, when the energy

contl-ibutioim of the triceps was ummecessary, time ankle simowed a total positive

i-otation of 28 to 30 degrees. Imi walking down time ramp, .JM showed mnore subtalar

motiomi aimd less ankle motion timan did l)GW. Since JM had aim hal)itual toeimmg-out

VOL. 46-A, NO. 2, MARCH 1964

382 D. G. WRIGHT, 5. M. DE5AI, AND W. H. HENDERSON

walk, the results were compatible with the universal-joint analogy.

It is interesting that the subtalar motion shown by JM during descent of the

ramp was entirely absent during ascent. This immobilization of the subtalar joint

allows the foot to be used as an efficient lever during active contraction of the

triceps surae.

In an attempt to minimize the effect of muscle action, tracings were made as

the subjects walked backward (Fig. 19). These patterns were similar to the reversed

normal patterns for the same subjects, except that the ankle patterns showed the

increased rotation associated with absence of action of the triceps surae. The pat-

terns for backward walking, if reversed, would be similar to those for walking down

the ramp. They also show more subtalar and less ankle motion for JM as compared

with DGW.

These tracings provide one of the most convincing arguments for ascribing a

universal-joint type of action to the subtalar and ankle-joint system. During stance,

with every positive rotation of the ankle joint, the subtalar joint shows positive

rotation. For every negative rotation of the ankle joint, the subtalar joint shows

negative rotation. If the original records are examined, the paired events are

seen to coincide. The implication is that the joints are interdependent, rota-

tion in one necessitating rotation in the other. The same coordination of the two

joints is seen in the other conditions of walking except when unusual muscle effort

is required, as in toeing-in, toeing-out, or uphill walking.

Normal Range of Subtalar and Ankle Motion

In the final study, an attempt was made to determine the normal range of

subtalar and ankle motion for one subject during level walking. The preceding

sections had established that a toeing-in or toeing-out position of the foot and

action of the triceps surae significantly altered subtalar and ankle motion, whereas

changes in cadence, stride length, and extent of arm swing did not.

The location of each axis was measured from the unit and was seen to be in

general agreement with the anatomical studies.

The average values for motion about the subtalar and ankle joints for the

first subject in stance phase were 6 degrees and 14 degrees of positive rotation, re-

spectively. The value of 6 degrees appears to be small, but when it is realized that

the ankle motion over the same period was only 14 degrees it can be appreciated

that the subtalar joint contributes significantly to the motion of normal level walk-

ing. This fact may explain the progressive laxity which has been observed to de-

velop in the ankle joint after subtalar fusion.

Conclusions

It is concluded that the subtalar joint plays a small but essential role iii the

motion occurring between the foot and the leg during the stance phase of mmormal

walking. It is further believed that the subtalar and ankle joints are interdependent

and in general act as a single mechanism during walking. The average subtalar

and ankle rotations for the stance phase were found to be 6 degrees and 14 degrees,

respectively, for one subject.

References

1. BARNErF, C. H., and NAPIER, J. R.: The Axis of Rotation of the Ankle Joint in Man. Its In-fluence upon the Form of the Talus and the Mobility of the Fibula. J. Anat., 86 : 1-9, 1952.

2. CALIFORNIA, UNIVERSITY OF, Prosthetic Devices Research Project: Fundamental Studies ofHuman Locomotion and Other Information Relating to Design of Artificial Limbs. [Report tothel Advisory Committee on Artificial Limbs, National Research Council. Berkeley, TheProject, June 1947.

(Continued on page 464)


464 PROCEEDINGS

patients. Shoulder flexion had decreased an average of 23 per cent; shoulder abduction, 28 percent; flexion at the elbow, 16 per cent; and extension of the elbow, 14 per cent. The normal forcedecrease of the left arm was found to be approximately 5 per cent, as compared with the right shoul-

der and arm in right-handed patients. Arm-length discrepancies were most sigimificalmt. Roent-

genograms made of both arms revealed an average loss of length of 1.5 centimeters of the left arm.The greatest arm-length difference was 2.2 centimeters. The longer after operation, the greater the

arm-length difference.

The author suggested that additional studies need to be made, such as the effect of left lateral

thoracotomy on the strength of the arm. After this procedure, endurance exercises proved ad-

ditional weaknesses of the left arm as compared with the right.

Dim. JOHN H. MOON 19 discussed a current therapy of multiple myeloma in wimicim he used

1-phenylalanine mustard to treat fourteen consecutive patients with multiple myelolmma at the

Medical College of Virginia. The criteria for judging results were: ( 1 ) improvement in anemia or

thrombopenia, (2) reduction in the amount of abnormal protein in the serum or urine, (3) decrease

in bone pain or healing of bone lesions, or both, (4) decrease in the amoummt of plasma cell infiltra-

tion of marrow, (5) increased resistance to infection, and (6) survival. This series of ulmselected

patients was compared with a published series in regard to the response rate. In this series of

patients, 43 per cent achieved some significant degree of palliation, which is considerably better

than the 20 per cent remission rate claimed for urethane. Although 1-phenylalanine nmustard is

not the complete answer to the therapy of multiple myeloma, it seems to he the best agent that is

currently available.

DR. EDWIN M. HAKALA 20 discussed the problems of fitting prostheses in juvenile amputees.

19. Medical College of Virginia, Richmond, Virginia.20. 2222 Monument Avenue, Richmond, Virginia.

REFERENCES

AevIoN OF THE SUBTALAR AND ANKLE-JOINT COMPLEX DURING STANCE PHASE OF \‘SALKING

(Continued from page 38�)

3. CALIFORNIA, UNIVERSITY OF, Prosthetic Devices Research Project: The Pattern of MuscularActivity in the Lower Extremity During Walking. A Presentation of Summarized 1)ata. lReportto thel Advisory Committee on Artificial Limbs, National Research Council. Series 11, Issue25, September 1953.

4. CLOSE, J. R., and INMAN, V. T.: The Action of the Ankle Joint. [Report to thel Advisory Com-mittee on Artificial Limbs, National Research Council. Prosthetic Devices Research Project,University of California, Berkeley, Series 11, Issue 22, April 1952.

5. CLOSE, J. It., and INMAN, V. T.: The Action of the Subtalar Joint. [Report to timej Advisor?Committee on Artificial Limbs. National Research Council. Prosthetic 1)evices ResearcProject, University of California, Berkeley, Series 1 1, Issue 24, �1ay 1953.

6. DESAI, S. M., and HENDERSON, W. H. : Engineering Design of an Orthopedic Brace. Bio-mechanics Laboratory, University of California, San Francisco and Berkeley. Technical ReportNo. 45. October 1961.

7. HICKs, J. H.: The Mechanics of the Foot: I. The Joints. J. Anat., 87 : 345-357, 1953.8. MANTER, J. T. : Movements of the Subtalar and Transverse Tarsal Joints. Anat. Rec., 80:

397-410, 1941.9. RYKER, N. J., JR.: Glass Walkway Studies of Normal Subjects During Normal Level Walking.

[Report to thel Advisory Committee on Artificial Limbs, National Research Council. Prosthetic

Devices Research Project, University of California, Berkeley, Series 1 1, Issue 20, January 1952.


Documents

Action of the Subtalar and Ankle-Joint Complex During the Stance Phase of Walking