Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a prosthetic device used to treat
a human joint by applying "continuous passive motion".
This application is a divisional of Application Serial No.
388,659, filed October 23, 1981.
The concept of "continuous passive motion" is described in
the article "Joints Were Meant to Move - And Move Again" by Ohlendorf
in "The Graduate", published by The Department of Information Services,
University of Toronto, September/October 19~0.
Briefly, according to this concept, a human joint, for example,
a knee, elbow, or finger joint, is kept under slow continuous con-
strained motion as distinct from being held motionless or being moved
intermittently. Keeping an injured or post-operative joint mobile
rather than immobilizing it in a cast is beneficial to the cartilage.
Attempts which have been made to provide machines that
exercise joints are designed for intermittent operation and do not
supply continuous passive motion.
An apparatus, according to the invention, includes a support
structure, usually a housing containing working parts. Harness means
mounts the support structure on the patient's body or, in an alter-
native arrangement, the support structure may be mounted on a crutchor bed. Traveller means is carried by the housing for reciprocating
movement relative to it and is connected to an extremity of thc limb
having the joint to be exercised so that the joint completes the
linkage. Motor means in the housing drives the traveller means back
and forth through a predetermined stroke with a slow rhythmic motion.
The present invention relates to an actuator for a prosthetic
device. The actuator includes an elongated support, traveller means on
the support for reciprocating linear movement relative thereto, and
means connected to the traveller means for operatively engaging a limb
of the body connected to a joint to be mobilized. There is motor means,
preferably on the support, for driving the traveller means back and
forth through a reciprocating linear stroke in a slow rhythmic cycle,
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whereby the limb is moved relative to the support so that the joint is
kept continually in motion. The motor means embodies means for revers-
ing the direction of travel o~ the traveller means at any point in its
path of travel responsive to a predetermined load.
In a preferred construction, the support is a housing having a
longitudinal slot defining a guide track, a traveller mounted for back
and forth motion relative to the housing, an inner tubular housing
mounted in the support housing, a longitudinally extending slot offset
relative to the guide track. A drive member is mounted inside the
tubular housing to drive the traveller in said back and forth motion.
The traveller includes a travelling element mounted inside the support
housing operatively connected through the longitudinally extending slot
in the tubular housing to the drive member. The travelling element is,
in turn, connected to a travel member mounted for travel along the
guide track. Desirably, the motor means is contained inside the housing.
The housing may be centrally disposed in the support and the drive
member centrally disposed in the housing.
The drive member may comprise a drive screw, mounted for
rotation inside the tubular housing, with the travelling element mounted
on the drive screw. The travelling element is restrained against
rotary movement so that rotary movement of the drive screw is con-
vertedintolongitudinal movement of the travelling element to move the
travel member along the guide track. The travelling element preferably
comprises nut means.
Desirably, the travelling element comprises an inner nut member
mounted on the drive screw, inside the tubular housing, and an outer
member held to the nut member by connecting means extending through the
longitudinal slot in the tubular housing. The outer member is mounted
to travel between the support housing and the tubular housing, and
includes a pair of spaced-apart terminal stops in the support housing
to define the predetermined normal stroke. The motor means is rever-
sible so thatitdrives the traveller ~irst in one direction and then
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in the other. Preferably, the means to reverse the direction of the
motor is also actuatable by predetermined resistance of the screw
member to rotation. Desirably, also, the motor means is housed inside
the support housing and the tubular housing is centrally disposed in the
support housing and the drive screw centrally disposed in the tubular
housing. Preferably, the motor means is carried by the support. Pre-
ferably, also, the motor means includes an electric motor, in which
case the means for reversing may be means to monitor electrical power
consumption as a measure of the appliecl load. The means reversing the
motor may also include a switch operatively connected to the motor
means to reverse the motor means responsive to the predetermined
excessive load.
Having thus generally described the invention, it will be
referred to more specifically by reference to the accompanying drawings,
which illustrate preferred embodiments, and in which:
Fig. 1 is a perspective view showing a unit for treating
an elbow ~oint;
Fig. 2 is a greatly enlarged fragmentary perspective view
showing the wrist connection in the unit of Fig. 1;
Fig. 3 is a schematic perspective diagram, of an exploded
nature, showing the arrangement of the parts in a unit;
Fig. 4 is a side elevation showing a unit for treating the
knee joint in which the unit forms part of a crutch;
Fig. 5 is a side elevation of a variation of the unit of Fig. 4;
Fig. 6 is a fragmentary perspective view showing an operating
unit for treating the knee joint and which is connected
to a bed on which the patient is reclining;
Fig. 7 is a fragmentary perspective view showing a unit for
treating a finger or thumb joint;
Fig. 8 is a perspective view of the unit shown in Fig. 7,
illustrating the drive rnechanism.
Referring more particularly to Fig. 1, the device is made
up of a support structure which, in this case is
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an elongated housing A connected to the shoulder by a harness
B and to the waist by a belt D. Actuator or traveller means,
movable relative to the housing, is connected to the wrist by
a cuff C. The traveller means is supported by the housing
for linear reciprocating movement relative to it. Motor
meanS drives the traveller means back and forth through a
~ predetermined stroke in a slow rhythmic cycle. This imparts
a corresponding reciprocating motion to the arm, thus impart-
ing continuous passive motion to the elbow joint.
The speed of movement of the actuator means would,
in the embodiment shown range from one-half foot to four
feet per minute or from one-third to two cycles per minute.
In order to supply supination and pronation to the
wrist, the cuf~ C is connected (see Fig. 2) to a special
mechanism. Mo~nted for rotation on a U-shaped bracket 15 is
a shaft 17, carrying a bevel gear 19, which meshes with a
crown gear 21, carried on a hub 23, mounted on a plate 25
forming a part of the traveller means.
The plate 25 moves back and forth, along the
housing A, and the flexing of the elbow causes rotation of
the arm at the wrist, by virtue of its connection to the
bevel gear 19 as it is ca~sed to ride around the crown gear
21. At the same time, the wrist is held to the plate 25 so
that it makes longitudinal movements with the latter along
the housing A.
Fig. 3 shows in detail the support housing,
actuating means, motor mea~s and associated parts. A motor
31 drives an elongated screw 33 whose opposite end is rota-
tably held in a recirculating ball-type nut 3~. ~A cylindri-
cal slide 35 is connected to the nut 32 and moved linearlyunder the drive of the screw 33 between the limiting stops
; 37 and 39, which are locked to the housing A by thumb screws.
The mechanism is encased in an outer tube 41 and
an inner concentric tube 42. m e tube 41 is provided with
a longitudinal slot 43 and the concentric tube 42 with an
elongated slot 45. The slot 43 accommoda-tes the flange
connection 48 between the slide 35 and the plate 25~ The
slot 45 accommodates the flange connection 46 between the
ball nut 33 and the slide 35.
The motor 31 is powered by batteries 47 which
operate through circuits on a circuit board 49 and is
governed by controls 51. The tube 41 is provided with a
gooseneck part 53 about which khere extends a bracket 55
connecting it to the harness B. The other end of the tube
41 has a terminal 56 provided with an eye 57 so that it can
be hung from a suitable hook when required.
The motor 31 is a reversible motor. It will
reverse as soon as an excessive load is applied~ This may
be, for example, where the actuator or traveller reaches
the end of its stroke and is halted by the stop 37 or 3g
as the case may be. Or, it may be where there is some
unplanned obstruction, for;example, sheets jamming in the
mechanism or where the patient offers undue resistance. A
safety function is thus performed as well as a prime actuat-
ing function.
Examples of suitable ~otors are geared D.C. Brush
type motors made by Faulhaber, Escap, and Maxon Precision,
all of Switzerland.
Fig. 4 describes an apparatus for flexing the knee
joint. Similar numbers have been applied to similar parts,
as on FigsO 1 and 3, with the excep-tion that they have been
raised by 100 and the letters have been given a subscript 1.
In this case, the support housing Al forms part of
a crutch for supporting the patient and embodies operating
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mechanism similar to~that shown in Fig. 3, except that the
housing Al is straight instead of having a gooseneck end.
It has a rubber foot 157 taking the place of the terminal 56.
A handle Bl takes the place of the harness B and is provided
with an armpit bar 159. The part Bl slides on the top end of
the support housing Al. Taking the place of the plate 25 is
a simple foot plate with straps, as compared with the supina-
tion and pronation mechanism for rotating the wrist.
Fig. 5 shows an alternative arrangement in which a
waistband B2 is employed to connect the top of a support
housing A2 to the body. A separate crutch D supports the
patient.
Fig. 6 illustrates a further form of leg exercising
device. In this case, the support housing of Figs. 4 and 5
is connected to a bed. It is retained by spaced-apart
brackets 61 and 62. The leg of a patient lying on the bed
is connected to the foot plate as in Figs. 4 and-5.
Fig. 7 illustrates a device for flexing finger or
thumb joints. Here aga~n a support housing A4 is connected
to a cuff B4 mounted on the wrist and hand in place of the
harness of Fig. 1. An actuator wire 425 moves back and forth
from the housing A4, through a flexible guide tube`441, to a
connection with the thumb.
The connection from the actuator wire ~25 to-the
thumb is through a hinge 443 to a small plate 445, adhesively
connected to the th~mbnail. Alternatively, the actuator
member 445 can be connected to any of the fingers or several
fingers at a time.
A mechanism for moving the actuator wire 425 is
shown in Fig. 8. The support structure is fashioned from a
hlock of plastic in which recesses have been made to accommo-
date the various parts. A geared motor 447 drives a sprocket
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432 about which there is trained a chain 433 which is also
trained about a spaced-apart sprocket 435. The actuator wire
425 is connected at 437 to one of the links of the chain 433.
Batteries 446 are accommodated within the block as is an
operating switch 451~ The motor moves the chain continuously
so that the actuator wire 425 moves in one direction along
the top run of the chain and then down along the bottom run
in the other direction so as to impart substantially con-
tinuous reciprocating movement to the wire 425 and conse-
qu~ntly to the hand joint.
From this detailed description it will be evident
that various modifications can be made within the spirit of
the invention to treat various joints of the body under
appropriate conditions~
SUPPLEMENTA~Y DISCLOSURE
This Disclosure and the Principal Disclosure are
concerned with a portable apparatus for imparting continuous
passive motion to a human joint~
Figs. 7 and 8 of the Parent Disclosure show a
device specifically directed to mobiliziny joints of hand
digits D
The applicant now aiscloses an apparatus within the
broad concept of the Parent Disclosure, but having mechanism
for mobilizing a plurality of digits of the hand, i~e. the
fingers and/or thumb. This mechanism is made up of a support
in the form of a cuff and means for mounting the support on
the forearm. Motor and transmission means is carried by the
support. Travelling means is movable by the transmission
means through an elongated path in a reciprocatingimovement.
A connecting rod is connected at one end of the travelling
means and connected to a manifold block or yoke. There is
means for connecting the block to several fingers whereby
their joints are mobilized as the manifold block is moved
back and forward by the travelling means.
In a preferred construction, the connecting rod
extends through an opening in the manifold to which it is
held by a set screw. Beyond the manifold the connecting rod
is pivotally connected to clevis means, mounted on a finger.
A separate wire connects the manifold bLock with clevis
means connected to several other fingers and/or to the
thumb, if desired.
A preferred way of connecting the clevis to the
finger incLudes a plate which rests on the surface of the
finger and a central lug extending -from it. An adhesive
strip having a central slot for the lug to project through
the slot surrounds the finger and holds the p:Late to it.
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A preferred form of this aspect of the invention
is illustrated in the following drawings in which:
Fig. 9 is a perspective view showing a hand
digit mobilizing device, according to
the invention, mounted on the forearm
of a patient and connected to several
fingers;
Fig. 10 is an exploded perspective view showing
the elements of the finger mounting means;
Fig. 11 is an enlarcJed plan view showing the
relationship between the manifold,
connecting rod and wire,
Fig. 12 is an exploded perspective view looking
at the top of the cuff and showing the
interlocking fabric connecting it to the
supporting housing, and
Fig. 13 is a side elsvation, enlarged in compari-
son with Fig. 12, illustrating particularly
the construct on of the mounting arrange-
ment on the ar~ and its relationship to
the drive housing.
Referring more particularly to the drawin`gs, Figs.
9 through 13 show an alternative form of device for mobiliz-
ing a joint of the hand as compared with that shown in Figs.
7 and 8.
The same reference numerals, in terms of tens and
digits, have been used to identify like parts, as in Figs.
7 and 8, but they have been raised into 500's and the
reference letters have been given the subscript S.
~he housing A5 is carried by a mounting arxangement,
indicated generally by B5. The arrangement B5 is supported
by the forearm and wrist.
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This mounting arrangement includes an extensive
~oam pad 553, which engages the surface of the forearm and
wrist. The pad 553 narrows to a neck part 555 which extends
over the palm of the hand. For mounting the pad 553 is a
saddle 554, of relatively rigid thin plastic, which also
narrows to a neck 556 which overlies the neck 555~
Mounted above the saddle 554 is a plate 557, which
narrows to a neck 559 which is held to the necks 555 and 556
by a--rivet 560.
la At its opposite or rearend, the plate 557 is
spaced from the saddle 554 by a ~rop 580, which in the form
shown is a tube having one end screwed to the plate 557 and
having the other screwed to the saddle 559.
A fabric anchoring loop 563 is riveted to the
margin of the saddle 554 midway along its length and carries
a metal eye 565 to receive a belt/ for surrounding the fore-
arm, which extends through an adjustable buckle anchored to
the other side of the saddle 554.
A belt 569, to surround the hand, is riveted to
the assembly of necks 555, 556 and 559. r~he belt 569 is
provided at one end with a buckle 570. The belt 569
encircles the hand just in front of the root of thè thumb.
By this arrangement, the plate 557 is supported
from the forearm with Its forepart strapped relatively
firmly to the palm of ~he hand and its rear part held
relatively firmly to the forearm. The plate is thus fully
supported from the forearm in a position for mounting the
housing A5~
To this end, the plate 557 carries a pad 551 of
the well known VELCR0 (trade mark) fabric having a pile
surface made up of a mass of small loops to engage a
complementary pad 550 on the undersurface of the drive
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housing A5, having the VELCR0 fabric surface made up of a
mass of hooks which anchor themselves to the loops of the
pad 551. The ~ELCRO anchorage of the pad 550 to the pad 551
is adequate to hold the housing in place in normal usage.
But, the pads 550 and 551 may readily be peeled apaxt by
pulling hard enough, for removal of the housing A5 from the
mounting arrangement B5.
In accordance with this form of the invention, an
actuator wire extends from reciprocating mechanism inside
the housing A5 (as illustrated in Fig. 8). There is slidably
mounted on the actuator wire 525 a cylindrical manifold block
or yoke 560, the block 560 having an axial opening through it
to accommodate the wire 525. There is a set screw 561
operating in a transverse tapped opening in the block 560 to
engage the wire 525 and maintain it in position.
The end of the wire 525 carries a clevis 582 pro-
vided with a tapped opening receiving the threaded end of
the wire 525. The clevis has a slot 562 dividing its end
into fingers 563 through which there extends a pin 564 to
engage a connecting pin and finger connector, as will be
described.
The connector includes a plate 565a which rests
against the surface of the distal part of the finger and is
held to it by an adhesive strip surrounding the finger. A
perforated lug 567 extends from the plate 565 through an
opening 562 in the strip 566 into the slot 562 and is
engaged by the pin 564. So with the strip 566 engaging the
finger, the clevis is pivotally held to the distal end of
the finger.
In a similar manner, the other fingers are connec-
ted to the block 560 by respective wires 572 each having a
threaded inner end, engaging a tapped opening in the b:Lock
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560, and a threaded outer end engaging a tapped opening in
a clevis similar to the clevis 582 and held to the finger in
the same way.
A preferred actuator wire 525 is of 16 gauge solid
music wire. Preferred wires 572 are of stranded 16 gauge
metal, e.g. steel, wire to give them more flexibility.
The operation of the djevice is as previously
described. The drive mechanism moves the actuator wire
525 back and forth in reciprocal movement which is trans-
mitted to the fingers through the wires 525 and 572 so that
the joints of all the fingers connected to the actuator are
mobilized at the same time.
Likewise, the thumb may be linked to the manifold560 by another wire as can the little finger which is shown
- free in the drawing.
