Note: Descriptions are shown in the official language in which they were submitted.
~ackground o~ the Invention
This invention relates generally to orthopedic braces,
and has particular reference to a novel knee brace construction
which permits the flexing movement of the brace to closely
simulate the rolling and sliding movement of the human knee. At
the same time, the brace is constructed so that when worn it
exerts pressure above and below the wearer's knee in the most
desirable manner from an orthopedic standpoint.
There is an extensive amount of prior art directed to
orthopedic braces and particularly knee braces, including U.S.
Patent No. 3,194,233 granted July 13, 1965 to A. C. Peckham, one
of the applicants herein. Most of the knee braces that have been
developed heretofore have a simple pivot connection between the
upper and lower portions oE the brace but it has become widely
accepted in recent years that the actual bending movement of
the human knee is a combination rolling and sliding movement.
Because of this, many of the braces with simple pivot type hinges
have caused discomfort to the wearers by restricting movement or
by binding and chafin~
Knee braces having hinge means which attempt to simulate
the actual bending movement oE the human knee are disclosed in
the following U~S. patents: No. 2,883,982 issued Apri] 28, 1959
to F. F. Rainey; No. 3,581,741 issued June 1, 1971 to M. Rossman;
No. 3,779,654 issued December 18, 1973 to R. V. Horne; No.
3,817,244 issued June 18, 1974 to G. No Taylor; No. 3,885l252
issued May 27, 1975 to H~ Nakajima; No. 3,945,053 issued March 23,
1976 to B. M. Hillberry et al and W. German Patent No. 28 23 302
issued December 14, 1978 to J. W. Goodfellow et al. Of these,
the Horne, Taylor, Hillberr~ and Peckham patents represent -the
closest prior art known to the applicants.
The Horne patent is actually directed to an artificial
knee joint bu-t the problem, of course, is the same. In the
Horne joint, first and second pivot hearing elements engage
first and second arcuate bearing surfaces on a pair of over-
lapping plates to interconnect the plates for controlled sliding
and pivoting action relative to one another. The Horne construc-
tion might allow the knee to follow a correct path while bending
but does not constrain the knee to follow such a path as does the
brace of the present invention. This is because at any point
either of the Horne joint halves is free to rotate about either
of the pivot elements and this means that at any point an
incorrect motion as well as a correct motion is possible.
In the Taylor patent, the knee brace comprises inner
and outer bracing structures each comprising two substantially
rigid, elongated arms. The first arm is bifurcated to provide
two parallel plate portions and the second arm has an end portion
that is received between the plate poxtions for articular motion
of the second arm relative to the first arm. The articular
motion is not constrained to follow any defined path as in -the
present invention but rather follows the action oE the individual
wearer's knee. This allows the Taylor brace to fulfill a pro-
tective function for a normal knee but it is not able to provide
a corrective function in an unstable knee.
The Hillberry patent discloses a prosthetic knee joint
including two bodies having surface portions in contact. The
bodies are movable relative to one another and are constrained
in the movement by the nature or the surfaces in contact and
flexible straps that are positioned about and also in contact
with the bodies. The construction of the Hillberry knee joint
is somewhat similar to that of the invention but, because it is
a prosthesis that replaces the natural joint, it cannot properly
simulate the movement of -the human knee during bending. Thus,
the correct path that -the knee must follow in bending is not
at the point of contact of the femur and tibia but i5 located
above the point o~ contact as will be explained hereinafter.
The knee brace of the Peckham patent differs from that of
the invention in that it has but a simple pivot connection
between the upper and lower portions of the brace and therefore
cannot simulate the rolling and slidiny movement of the knee.
The Peckham patent does disclose a pressure exerting means that
]0 has a counterpart in the brace disclosed herein. However, in
the patented brace the pressure means completely encircles the
knee and generates force essentially through tension whereas
in the brace of the invention the pressure means extends only
half way around the knee and generates force primarily through
torque~
Summary of the Invention
. . ~
The disclosure herein makes particular reference to a
knee brace. However, it is not intended that the invention be
restricted to a brace for the knee as it will be apparen-t from
~0 the descr~ption to follow that the construction of the brace
enables it to be advantageously used with other joints having a
bending motion similar to the knee.
Ideally, a knee brace should prevent unphysiologic motion
in a normal knee and also prevent unphysiologic motion in an
unstable knee, thus performing both protective and corrective
functions. To achieve these goals, the brace should cancel or
prevent abnormal knee motion, duplicate normal knee motion,
provide rigid fixation and do no damage to the tissue. Stated
another way, the brace should be as rigid as practicable while
at the same -time simulating normal knee motion. Other desirable
features of a knee brace are to allow full range of motion, be
lightweight and durable, be painless in application and be
adaptable to many sizes.
The ]cnee brace of the invention closely simulates the
normal rolling and slidin~ movement oE the knee t provides the
desired rigidity and also includes the other desirable fea-tures
mentioned above. The simulated knee movement is accomplished
in the brace by a novel roller and inclined plane mechanism
coacting with flexible interconnecting cables, the movement of
the roller being both rotational and transla-tional. The cables
provide for movement that is smoo~h and also serve to connect
the upper and lower portions of the brace togetherO The roller
and plane mechanism is located so that when the brace is worn
the mechanism is above the point of contact of the femur and tibia
as it must be to properly simulate the movement of the knee
during bending.
The upper portion of the knee brace includes a pair of
pressure pads engageable with opposite sides of the wearer's
leg above the knee, and the lower portion of the brace includes
a pair of pressure pads engageable with opposite sides of the
~0 wearer's leg below the knee. The brace is also provided with
a toggle mechanism that operates when ~he brace is worn to
cause the upper and lower pressure pads to exert inward pressure
on the wearer's leg above and below the knee. The toggle mechanism
and pads thus coact to provide the desired rigidity, and the
inward pad pressure also functions to force the femur and tibia
towards one another by means of vector forces as will be ex-
plained in more detail hereinafter.
Brief Description of the Drawings
Fig. 1 is a front elevation of a knee brace of the inven-
tion with parts broken away and shown in section to he-tter
illustrate the details of construction;
Fig. 2 is a left side elevation o-E the brace of Fig. l;
Fig. 3 is a top plan view of the brace of Fig. 1 with
certain parts omitted for clarity;
Fig. 4 is a horizontal section through one of the strap
latch members taken on line 4-4 of Fig. 2;
Fig. 5 is a simplified diagram illustrating the rolling
and sliding movement of the knee as it bends;
Fig. 6 is a diagram illustrating the resultant forces
of the pressure pad pressures on the leg bones;
Fig. 7 is a vertical section taken on line 7-7 of Fig. 1,
the section showing details of the hinge mechanism of the
invention;
Fig. 7A is a simplified view corresponding to Fig. 7
illustra-ting the location of the hinge mechanism relative to the
contact area of the femur and tibia;
Fig. 8 is a view corresponding to Fig. 7 but showing the
parts rotated with respect -to one another;
Fig. 9 is a fragmentary front elevation of the toggle
mechanism showing the toggle latch in open position;
Fig. 10 is a view corresponding to Fig. 9 but showing the
toggle latch in closed position;
Fig. 11 is a transverse section through the latch taken
on line 11-11 of FigO 9;
Fig~ 12 is an e~ploded view of the right side of the
brace, with straps omitted, looking from outside -the brace a-t
the rear thereof;
Fig. 13 is an enlarged cross section through the roller
of the mechanism shown in Figs. 7 ~nd 8; and
Fig. 14 is a longitudinal cross section through the
toggle latch mechanism taken on line 14-1~ of Fig. 10.
-- 5 ~
Description of the Preferred Embodimen-t
Having reference now to the drawings, and wi-th par-ticular
reference to Figs. 1-3, -the knee brace of the invention is
essentially comprised of a pair of upper pressure pads 14~14,
a pair of lower pressure pads 15-15 and means connecting the
upper and lower pads together for relative movement therebetween,
the connecting means being generally indicated at 16-16. Each
upper pad 14 comprises a rigid pad holder 17, preferably of
plastic, and a flexihle pad 18 that is preferably filled with a
commercially available ma-terial marketed under the name l~ansen
Flowlit ~. Similarly, each lower pad 15 has a rigid pad holder
20 and flexible pad 21.
A generally rectangular plate 22 is secured as by screws
2~ to the outside of the pad holder 17 of each upper pad 14.
These plates extend downwardly for a distance below the pads as
best shown in Fig. 1, and each plate is offset inwardly at its
approximate midpoin-t as best shown at 25. The lower portion
of each plate 22 is wider than the upper portion and is rounded
to a g~nerally circular shape as shown at 26 in Fiys. 7 and 12
A pair of plates 27, similar in shape to plates 22, are
respectively secured to the lower pressure pads 15 as by
screws 28, Figs. 1, 2 and 7. Plates 27 extend upwardly into
spaced, confronting relation with the inwardly offset portions
of plates 22 as shown in Fig. 1.
Fig. 1 is a front elevation of a brace for -the right
knee. Accordingly, the upper and lower pressure pads 14,15
on the left side of Fig. 1 engage the outside of the wearer's
leg and pads 14,15 on the right side engage the inside. In
this connection, it will be seen that the pads 14,14 on the
right or inside are spaced from their respective plates 22 and
30 27 by posts 30 and 31 through which the connecting screws 24
38~
and 28 respectively pass. This arrangement is necessary in
that it allows the pad positions to substantially conform to
the taper of the leg while enabling the two sets of confronting
plates 22,27 on the opposite sides of the brace to be parallel
to each other as is necessary for proper operation of the plate
connecting means. The connecting means are positioned between
~he plates and are to be presently described.
The lower pressure pads 15 are rigidly secured to their
respective plates 27 by upper and lower posts 31 and screws
28, Figs. ] and 2. The upper pressure pads 14 are connected to
their respective plates 22 adjacent the upper edges of the
pads only, resultlng in connections that are more flexible.
This permits a fine ad~ustment of the angular position of the
pads to conform closely to the wearer's leg.
The upper pad adjustment is carried out by a generally
U~shaped spring member 32 and an adjustment screw 34, Fig. 1,
for each pad. Each spring member is secured at one end to
plate 22 as by a screw 35 and the opposite end of the spring is
free and bears against the outside of the pad 14 as shown. The
~0 inner end of the adjustment screw 3~ normally engages the free
end of the spring member and the position of the pad is adjusted
by moving the screw in or out. The adjustment screw is suppor-ted
by a bloc~ 36, Figs. 1, 2, 7 and 12, connected as by screws 37
to a 90 flap or flange 38 on plate 22 and a similar flap ~0
on an outer plate 41. The plate 41 on each side of the brace,
Fig. 1~ is conne~ted as by screws 42 to pla-te 22, there being a
-! bearing plate 44 of Teflon or the like between plates 22 and 41.
The connecting means 16, Figs. 1, 2 and 7, for the upper
and lower pressure pads includes the previously described upper
and lower plates 22,27 and a roller and inclined plane mechanism
that coacts with flexible interconnecting cables. The roller-
inclined plane mechanism and cables are located between the
confronting portions of plates 22,27 on each side of the brace
and permit the upper and lower portions of the brace to move
relative to one another with a rotational and translational
movement that closely simulates the hending movement of the human
knee. Since the roller-inclined plane mechanism is the same for
each side of the brace only one such mechanism will be described.
Referring to Figs. 1, 7 and 12, the mechanism includes a
bearing pad 46 secured to the llpper plate 22 and a bearing pad
47 secured to the lower plate 27, both bearing pads being made
10 of a plastic material such as Teflon. A roller 48 is positioned
between the bearing plates, the roller being rotatably connected
to- plate 27 only as by a screw 50O Roller 48 is received with a
clearance in an arcuate recess 51, Fig. 7, in bearing pad 47
and engages a straight, inclined surface 52 on bearing pad 46.
~s used herein, "inclined" is intended to mean an obliquely
disposed surface or one inclined to ~he horizontal. In the
embodiment disclosed, the surface or plane 52 is disposed at an
ancJle of approximately 30 to the horizontal, and its location
is important to the proper operation of the knee brace.
A pair of flexible cables 54 and 55 of constant length
coact with the roller 48 and inclined surface 52, Figs~ 7 and
12, the cables engaging a portion of the periphery of the roller
as shown in Fig. 7 and being received in a peripheral recess 56,
Figs. 1 and 13. Cable 54 is anchored at one end 57, Fig. 7,
to the lower bearing pad 47 and at its other end to a screw type
tension adjustment 58 adjacent the upper bearing pad. See also
Fig. 12, Cable 55 i5 anchored at one end 60 to bearlng pad 47
and at its other end to a tension adjustment 61 adjacent the upper
bearing pad. The tension adjustments 58 and 61 are respectively
30 sec~lred to flaps or flanges 62 and 63 on the upper bearing pad
-- 8 --
plate 22, the flaps being integral with the plate and disposed
at right angles there-to, Fig. 12.
Cables 54,55 control the relative movement between roller
48 and the inclined surface 52 on bearing pad 4~; the cables also
operate to hold the upper and lower plates 22,27 together and thus
the upper and lower pressure pads 14,15. When plate 22 moves
relative to plate 27 or vice ~ersa, ~he roller 48 rotates about
its center and at the same time the center of the roller itself
moves linearly because the entire roller moves along the inclined
surface 52. The linear movement of the center of the roller
parallel -to the inclined surface is referred to herein as trans-
lational movement by which is meant the roller moves along a
defined path. S~ated another way, roller 48 rolls wi-thout slippage
along the path defined by the inclined surface 52. This can be
best seen from a comparison of Figs. 7 and 8 wherein upper plate
22 has moved in a clockwise direction relative to lower plate 27
as when the wearer of the brace moves from a standing position
(Fig. 7) to sitting or squatting position (Fig. 8).
From comparing Fig. 8 with Fig. 7, it can be seen that
~0 pxessure pad 46 with its inclined surface S2 has been rotated
thxou~h approximately 115 in the clockwise direction and that
the position of the roller 48 relative -to inclined surface 52
has changed. Thus, in Fig. 7 the roller is positioned near the
upper end of the incline, whereas in Fig. 8 it is positioned
adjacent the lower end. The movement just described simulates
the bending movement of the human knee as shown diagrammatically
in Fig. 5.
The motion or ]cinematic ac-tion of the knee as it bends
was analyzed by Drs. Fran]cel and Burstein in their book
30 Orthopaedic Biomechanics (I,ea & Febiger, 1970, pp. 138 and 13g)~_
_ g _
and Fig. 5 is derived from this book. In FigO 5, as the femur
64 mo~es clockwise from its solid line to its phantom line
position, the "instant centers" or pivot points for both the femur
and tibia 65 change, the instant centers for the -tibia being
i, indicated by the dots 66 and the instant centers for the Eemur
being indicated by an almost straight line 67. From this diagram
it can be seen that the line 67 for the femur appears to roll
clockwise around and along the arcuate path outlined by the
dots 66 as the femur 64 moves clockwise. In the rotating and
10 translating mechanis~l of the invention, the inclined surface
52 corresponds to line 67 and the path of the contact points of
the roller 48 corresponds to the arcuate path formed by dots 66.
In this connection, it should be noted that the inclined surface
52 could be contoured slightly -to conform to the path of move~
ment of -the knee of a particular individual in which case the
brace would be completely customized.
From Fig. 5 it can be seen that the path of movement
of a stable, normal knee is located above the point of contact
or contact area o-E the femur and tibia. Accordingly, in order to
20 properly simulate the movement of the knee, it is very important
that the roller-incllned plane mechanism of the invention be
cor.respondin~ly located when the brace is worn. This is best
shown in Fig. 7A where it can be seen that the roller 48 and
inclined surface 52 are located above the contact area of the
femur 64 and tibia 65 when the brace is properly positioned on
the leg. ~t is to be noted that the brace will naturally tend
to self-locate in the proper position during -fitting.
The upper pressure pads 14 are encircled by a lea-ther
or fabric strap 69, Figs. 1-3~ the strap being connected to -the
30 right hand plate 22 by a metal strip 70 and to the left hand
plate 22 as by rivets 71, F~g. 2. The strap 69 has a buckle 72
-- 10 --
a-t the front of the brace for providing an approxima-te length
adjustment~ The strap also has a free end 74 with a heavy
wire loop 75 that is engageable with a quick opening and
closing over-center latch 76. The latch 76 is connected as
by a screw or rivet 77, Fiy. 1, to the left hand plate 22
and has a series of notches 78, Figs. 3 and 4, for providing
a flne adjustment for the strap length.
The lower pressure pads 15 are encircled by a leather
or fabric strap 80 having essentially the same construction
as strap 69 and connected in the same manner to lower plates
27. Strap 80 is also provided with a quick opening and closing
over-center latch 81, Figs. 1 and 2.
The pressure pad encircling straps 68 and 80 help to
hold the brace in position on the wearer's leg but the means
~or applying inward pressure through the pressure pads is a
toggle mechanism ~enerally indicated at 82 in Figs. 1 and 2.
Toggle mechanism 82 comprises a pair of rigid, curving arm
members 84 and 85 that extend from points 86 on the opposite
sides of the knee joint forwardly and downwardly -to a point in
front of the leg below the knee wtlere the arm members are
connected together by a linkage to be described~ At the points
86 on the opposite sides of the knee joint, the upper ends of
the toggle arms 84,85 are respectively connected to opposite
plates 27 as by screws 87. While the toggle mechanism is shown
in the drawings as being located at the anterior side of the
knee, it may be advantageous for certain applications of the
brace to locate it at the posterior side.
The linkage connec-ting the lower encls of -toggle arms
84,85 includes a front plate 88, Figs. 9, 10 and 14, having
a circular boss 90, Fig. 1~, on i-ts back sicle to which -the
ends of the toggle arms are pivotally connec-ted by means of a
screw pivot connection 91. The boss 90 serves to space the
plate 88 from the arms, and in t:he space provided there is a
)d~
latch arm 92 one end of which is pivotally connected at 9~
to toggle arm 84, Figs. 9 and lO. A link plate 95 is also
positioned in the space between the front plate and arm 84
with one end of the link plate being pivotally connected at
96 to the front plate and its other end being pivotally
connected at 97 to latch arm 92. The latch arm and link pla-te
thus have an over-center relationship as may be seen from
Figs. 9 and lO.
Moving the latch arm 92 from its open position of
Fig. 9 to its closed position of Fig. 10 causes the pivot
point 94 between the latch arm and toggle arm ~4 to move counter
clockwise around the link plate pivot 97, and this moves the
toggle arm upwardly or in a clockwise direc-tion as viewed in
Figs. l, 9 and lO. Upward movement of the toggle arm 84
relative to the other arm 85 has the effect of moving the upper
ends of the two arms closer together at the points 86, Fig. l,
and this results in a positive inward pressure at the opposite
sides of the knee which is necessary for the brace to perform
effectively. Referring to the diagram of PigO 6, the pressure
applied by the toggle mechanism at points 86 on the brace is
indicated by the arrows 98 and because of the shape of the
leg bones the horizontal forces represented by arrows 98 have
resultant forces as shown by the oblique arrows 100, these
being the forces applied by upper and lower pressure pads 14
and 15. The forces represented by arrows lO0 urge the ends
of the femur and tibia toward.s one another which is very
desirable as it minimizes the possibility of twisting.
Referring again to the toggle mechanism, FigsO 9~11,
a size adjustment is provided at lOl comprising a boss 102
on the front plate 88 having a tapped hole and a boss 104
on the toggle arm 85 having an untapped hole~ A knurled headed
adjustment screw 105 passes with a free fi-t through the boss 104
and is threaded into boss 102. The underside of the head 106
of the screw bears against a notch 107 in toggle arm 85 and
by turning the screw in or out the angular adjustment between
the toggle arm and front plate 88 can be changed. This causes
the distance between the upper ends o~ the toggle arms at
points 86 to increase or decrease regardless of the position
of the front latch mechanism~
When applying the brace to the wearer 15 leg, upper and
lower strap latches 76 and 81 are open as is the la-tch arm
92 of the toggle mechanism. The brace is put on the leg with
the upper and lower pressure pads 14,15 comfortably positioned
above and below the knee and the latches 76 and 81 are then
engaged with their respective wire loops to hold the brace
in place without exerting any significant pressure on the knee.
In an initial wearing~ the upper and lower straps 69 and ~0
may be adjusted at their respective buckles but thereafter this
usually need not be done. After the brace is in position on
the leg, the latch arm 92 of the toggle mechanism is closed
to cause pressure to be exerted on opposite sides of the knee
as described above. The toggle mechanism, in conjunction
with the upper and lower pressure pads and pressure pad
plates 22 and 27, also imparts to the overall rigidity that
is desired.
From the foregoing description, it will be apparent
that the invention provides a relatively simple yet very
advantageous knee brace or the like having a novel mechanism
to enable the brace -to simulate the rolling and sliding
movement of the human knee and also having a novel toggle
mechanism that causes pressure to be exerted in a most bene-
ficial manner on the opposite sides of the knee. As will beunderstood by those familiar wi-th the art, the invention may
be embodied in other specific forms without departing from the
spirit or essential characteristics thereof.
- 13 -
