U.S. patent number 3,701,349 [Application Number 05/142,907] was granted by the patent office on 1972-10-31 for bi-valved cast.
Invention is credited to Leighton W. Larson.
United States Patent |
3,701,349 |
Larson |
October 31, 1972 |
BI-VALVED CAST
Abstract
A bi-valved cast for immobilizing broken limbs in which
complementary rigid shells, each having an inflatable liner, are
releasably secured together about the limb or other body portion to
be immobilized, so that upon pressurizing the liners, the limb or
other body portion will be immobilized. A significant feature of
the disclosed invention resides in the provision of air entry
passages through which ventilating air reaches the interface
between the immobilized limb and the inner surfaces of the
inflatable liners.
Inventors: |
Larson; Leighton W. (Waconia,
MN) |
Family
ID: |
22501762 |
Appl.
No.: |
05/142,907 |
Filed: |
May 13, 1971 |
Current U.S.
Class: |
602/14;
602/13 |
Current CPC
Class: |
A61F
5/05816 (20130101) |
Current International
Class: |
A61F
5/058 (20060101); A61F 5/04 (20060101); A61n () |
Field of
Search: |
;128/87-89,93,82.1,DIG.20 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Trapp; Lawrence W.
Claims
The invention is defined by the following claims:
1. In a bi-valved cast for immobilizing a body portion, wherein the
cast comprises complementary separate rigid shells, which when
joined together form a rigid cast conforming in contour to the body
portion to be immobilized, wherein means are provided to releasably
secure the shells in joined relation, and wherein each shell has an
inflatable liner extending over substantially the entire inner
surface thereof so that the introduction of air under pressure into
the liners after the shells are secured in joined relation
immobilizes the body portion in the cast, the improvement which
resides in:
means for introducing air from the exterior of the cast to the
inner surface of the liners so that the interface between an
immobilized body portion and the liners is ventilated.
2. The bi-valved cast of claim 1, wherein said means for
introducing air to the inner surface of the liners comprises
perforated tube means on the inner surface of the liners, said
perforated tube means having open ends opening to the exterior of
the cast.
3. The bi-valved cast of claim 2, wherein said tube means comprises
open ended perforated tubes affixed to the inner surface of the
liners, with at least one open end thereof projecting beyond an
extremity of the liner so as not to be closed when the liner is
pressurized.
4. The bi-valved cast of claim 1, wherein said means for
introducing air to the inner surface of the liners comprises means
sealing the inner and outer walls of the liners to one another at
spaced apart localized areas, openings through said localized
areas, and openings through the walls of the shells.
5. In the bi-valved cast of claim 1, the further improvement which
resides in the means for releasably securing the rigid shells in
joined relation and which comprises:
A. a locking pin rotatably mounted on an edge portion of one shell
and protruding therefrom for entry into a hole in the adjacent edge
portion of the other shell;
B. interengageable means on the locking pin and said adjacent edge
portion of said other shell to secure the locking pin against
withdrawal from said hole when the locking pin is turned; and
C. means on the locking pin by which the same may be turned,
said last named means requiring the use of a special tool.
6. A bi-valved walking type cast for immobilizing a foot,
comprising:
A. complementary separate rigid shells which, when joined together,
form a rigid cast conforming in contour to the foot to be
immobilized,
said shells being generally channel shaped in cross section and
having edges which mate when the shells are joined, one of said
shells being shaped to embrace the heel of the foot and the other
shell being shaped to overlie the front of the foot;
B. retaining means on the shells for releasably securing the same
in joined relation;
C. inflatable liner means in each shell extending over
substantially the entire inner surface thereof,
the liner means in said shell which embraces the heel of the foot
being divided into two separate compartments, one of which
underlies the sole of the foot and the other of which embraces the
back of the lower leg; and
D. air introduction means on said liner means including one for
each of said separate compartments of the liner means in the shell
which embraces the heel, through which said inflatable liner means
may be pressurized to immobilize the foot in the cast.
7. The bi-valved cast of claim 6, further characterized by a heel
secured to the underside of the shell which is shaped to embrace
the heel of the foot.
Description
BACKGROUND OF THE INVENTION
The invention relates to the field of immobilizing broken limbs and
other body parts through the use of a cast or splint. In the past,
this was customarily done by a plaster-of-paris cast formed in situ
about the body part to be immobilized. Since a plaster-of-paris
cast can not be opened or removed without destroying it, such a
cast could not be re-used, nor did it permit visual inspection of
the limb, and of course adjustment of the cast to compensate for
swelling and contraction of the immobilized limb was out of the
question.
There have been a number of efforts to depart from the traditional
plaster-of-paris cast in favor of a lighter, reuseable and
adjustable cast. There have also been efforts to make casts which
may be opened for visual inspection of the limb, and reclosed when
the inspection is completed. None of these prior art devices,
however, offer the advantages of the present invention.
The Ramirez U.S. Pat. No. 3,032,033, for example, discloses a
resin-impregnated fiberglass shell which includes two halves that
are secured together to form a cast that conforms to the shape of
the limb to be immobilized. The Ramirez cast, however, does not
include any means for adjusting or compensating for the difference
in configuration between the limb and the shell of the cast. In
other words, the rigid shell portion must be formed with extreme
care to insure taht it conforms accurately to the shape of the limb
which is to be immobilized. By contrast, the present invention
provides for substantial adjustment to insure that the immobilized
limb will be tightly held even though there may be differences in
shape and size between the cast and the limb. Moreover, the present
invention allows for continued adjustment to compensate for
swelling or a decrease in size of the immobilized limb.
The Gottfried U.S. Pat. No. 3,153,413 discloses an inflatable
pressure bandage-splint which provides adjustability to compensate
for swelling or decrease in size, but it does not include a rigid
outer protective shell. In addition, the Gottfried bandage-splint
provides for visual access and reclosing of the device. There is,
however, a lack in uniformity in the thickness of the inflatable
liner from a maximum thickness opposite the closure means to a
complete lack of thickness at the closure means. The lack in liner
thickness at the closure means along with the lack of a protective
rigid outer shell limits the value of the Gottfried design to
temporary or first-aid type applications.
Casts have also been made of plastic foam, as disclosed in the
Gibbons U.S. Pat. No. 3,403,676. While initially there is excellent
conformance between the plastic foam cast and the immobilized limb,
there is no way of adjusting the inside cavity of the cast as the
immobilized limb swells or decreases in size.
S U M M A R Y
THe present invention is an improvement over that of the copending
application, Ser. No. 780,335, filed Dec. 2, 1968, now U.S. Pat.
No. 3,580,248. As disclosed and claimed in said U.S. Pat. No.
3,580,248, the device of the instant invention comprises two rigid
complementary shells releasably secured together to form a rigid
cast which conforms in shape to the limb or other body portion to
be immobilized, and which may be opened to afford access to the
immobilized body portion. An inflatable liner disposed in each of
the rigid shells extends over substantially its entire inner
surface, and valved air introduction means on the outside of the
rigid shells provide for inflating each of the liners. A layer of
absorbent material is preferably placed between the liners and the
immobilized body portion.
In addition to the provision of convenient access without
destruction of the cast, the present invention, like that of the
aforesaid U.S. Pat. No. 3,580,248 makes adjustment of the cast a
simple matter. More particularly, as the limb swells or contracts,
the pressure in the inflatable liners may be varied to compensate
for the swelling or contraction and thereby maintain a constant
pressure on the limb. Moreover, pressure may be varied, within the
limits necessary to immobilize the limb, to provide for individual
patient comfort.
The bi-valved cast of the present invention also need not conform
accurately to the shape of the body portion which is to be
immobilized, since the inflatable liners can compensate for such
difference as might be encountered. And, finally, as in the patent,
the cast of the present invention is substantially lighter than
most casts, particularly the plaster-of-paris cast, yet provides
equivalent protective and immobilization strength.
One of the objects of this invention is the provision of means for
ventilating the interface between the immobilized limb and the
layer of absorbent material in which it is wrapped.
It is also an object of the present invention to provide a
walking-type cast embodying the advantages of the bi-valved
formation of the aforesaid patent.
Still another object of the instant invention is to provide
improved locking means for securing together the complementary
sections or half shells of the bi-valved cast, by which the
securement is more readily effected and unauthorized opening of the
cast -- as by the patient himself -- is precluded.
With these observations and objectives in mind, the manner in which
the invention achieves its purpose will be appreciated from the
following description and the accompanying drawings, which
examplify the invention, it being understood that changes may be
made in the specific structure disclosed herein without departing
from the essentials of the invention set forth in the appended
claims.
The accompanying drawings illustrate several complete examples of
the embodiments of the invention constructed according to the best
modes so far devised for the practical application of the
principles thereof, and which:
FIG. 1 is a perspective view of the bi-valved cast of the present
invention, in its closed position, but without association with the
limb -- in this case the lower leg -- for which it is intended;
FIG. 2 is a cross sectional view of the cast shown in FIG. 1,
applied to the limb to be immobilized;
FIG. 3 is an enlarged sectional view of the means for releasably
securing the two complementary shells together, as employed in that
embodiment of the invention illustrated in FIGS. 1 and 2;
FIG. 4 is a longitudinal sectional view of the cast showing the
relationship between the cast, the inflatable liners, the absorbent
padding material and the immobilized limb;
FIG. 5 is a perspective view similar to FIG. 1, illustrating an
improved embodiment of the bi-valved cast of this invention;
FIG. 6 is a cross sectional view through FIG. 5 on the plane of the
line 6--6;
FIG. 7 is a cross sectional view through FIG. 6 on the plane of the
line 7--7;
FIG. 8 is a perspective view of the upper end portion of the lower
shell of the cast shown in FIG. 5, and illustrating one way of
providing ventilating air circulation to the immobilized limb;
FIG. 9 is a longitudinal sectional view showing another way of
achieving the desired ventilating air circulation; and
FIG. 10 is a vertical section view of a walking type cast embodying
the principles of this invention.
Referring now more particularly to the accompanying drawings, and
initially to FIG. 1, it will be seen that the bi-valved cast 10 in
accordance with the present invention, includes an upper rigid
shell 11 and a lower rigid shell 12. The shells 11 and 12 are
complementary and coact to provide a rigid enclosure conforming to
the general shape of the limb or body portion which is to be
immobilized -- which, in the case illustrated, is a leg. Each of
the shells has a generally channel-shaped cross section, the two
edges of which mate, as at 13 and 14, with the edges of the other
shell.
Each of the shells is provided with an inflatable liner. Liner 15
is nested in the rigid shell 11 and liner 16 is nested in rigid
shell 12. These liners extend over substantially the entire inner
surface of rigid shells 11 and 12, respectively.
A valve 20 protrudes from the rigid shell 11 through which the
liner 15 may be inflated, and a similar valve 21 protrudes from the
lower rigid shell 12 to provide for inflating the liner 16.
Layers of absorbent material, such as sheet wadding 22 and 23, line
the inner walls of the inflatable liners 15 and 16, respectively,
to make direct contact with and enwrap the immobilized limb.
THe means for releasably securing the rigid shells 11 and 12 in
mating relationship, as shown in FIG. 1, comprises a bracket 25
secured to the upper rigid shell 11, as by rivets 26, and a lower
bracket 27 secured to lower shell 12, as by rivets 28. A screw eye
29 is pivoted to each lower bracket 27 and passes through a slot in
its companion bracket 25 so that, by tightening a wing nut 30,
which is threaded onto the screw eye, the two shells can be held
tightly together. The brackets 25 project beyond the adjacent edge
of the shell 11 to engage the edge portion of the shell 12 and
thereby hold the shells against lateral displacement when the
bi-valved cast is in its closed condition. The pivotal connection
between the screw eyes and the lower brackets 27 enables the
bi-valved cast to be opened with a hinge action upon loosening of
the wing nuts along one of the two mating edges.
While the specific embodiment shown is for immobilization of the
lower leg from a point above the knee to a point below the heel,
the bi-valved cast which comprises the present invention may be
used for a wide variety of other applications. More particularly,
it may be formed with a rigid shell conforming in shape to other
parts of the body, so that it may be used for fractures of the
calcaneus, metatarsals, fibulas, tibias, femure, fractures of the
body of vertebra, fractures of vertebral bodies, clavicular
fractures, metacarpal fractures, etc. It is therefore contemplated
that the present invention may be used as an upper leg cast, lower
leg cast, an upper arm cast, a lower arm cast, a body spica, a foot
cast, a neck cast, and a hand cast.
As shown in FIG. 10, the invention is especially well adapted to a
walking type cast. In this case, the lower rigid shell 12' defines
the heel portion of the cast and the upper shell 11' supplies the
front part of the cast. A significant feature of this embodiment of
the invention resides in the fact that the inflatable liner 16' of
the lower shell is divided into two separate chambers or
compartments 33 and 34 by a transverse seal 35. This seal can be
formed in any suitable way as long as it is air tight and is so
located that one of the two resulting chambers or compartments --
in this case, the one designated by the numeral 33 -- underlies the
sole of the foot and the other embraces the back of the heel and
lower portion of the leg. These two chambers or compartments have
their own air admission valves, indicated at 36 and 37.
As will no doubt be obvious, the separation of the inflatable liner
16' into a sole compartment and a leg compartment enables
maintenance of the desired pressure within the cast, despite the
added pressure resulting from the weight placed on the sole during
walking. It should also be apparent that the two compartments could
be provided by two separate appropriately shaped liners, each
individually placed in the shell 12'.
The lower shell 12' is preferably increased in thickness at the
bottom of its shell portion, as at 38, to facilitate attachment
thereto of a rubber heel 39.
An especially valuable attribute of the present invention is the
provision for ventilating the interface between the encased limb or
body portion and the directly adjacent absorbent material. Two
different ways of achieving this objective are illustrated. In one
of these, most clearly shown in FIGS. 5 and 8, the inner wall of
each inflatable liner, i.e. the wall that is adjacent to the
absorbent material, has a plurality of tubes 40 fixed thereto.
These tubes have open ends contiguous to the opposite extremities
of the cast, but so placed that they will not be closed when the
liners are inflated, and perforations 41 along the length thereof
opening to the absorbent material.
In the other embodiment of the ventilating feature, illustrated in
FIG. 9, the inner and outer walls of the inflatable liners are
adhered together at spaced localized areas, as at 42, and these
adhered areas have holes 43 which align with holes 44 in the rigid
shells.
Another improvement upon the embodiment of the invention
illustrated, disclosed and claimed in the aforesaid U.S. Pat. No.
3,580,248 concerns the manner in which the complementary shells are
secured together. As shown in FIGS. 5, 6 and 7, the mating edges of
the shells are rabbetted all along the length thereof, as at 45, to
hold the shells against relative transverse displacement. At spaced
intervals, the edges of the shells have integral lugs or
enlargements 46 and 47 in line with one another. The lugs 46, which
are on the upper shell 11, have a counterbored hole 48 in which a
rotatable pin 49 is located. The pin has a head 50 which is
received in the counterbore of the hole, with a compression spring
51 between its underside and the bottom of the counterbore. The pin
projects from the bottom of the lug 46 where it has diametrically
opposite projections 52 to engage the underside of the adjacent lug
47 when the pin is inserted through a hole 53 in the lug 47. As
shown in FIG. 7, the hole 53 has diametrically opposite grooves 54
to accommodate the projections 52, providing the pin is in proper
rotational orientation with the hole 53. Hence, upon entry of the
pin into the hole 53 and the application of downward pressure on
the pin to compress the spring 51, the pin can be rotated to
disengage its projections 52 from the grooves 54 and engage them
under the bottom of the lug 47.
The operation of depressing the pin 49 and rotating it is best done
with a special wrench, such as an Allen head wrench, shaped to fit
a specially shaped socket 55 in the head of the pin. By this
expedient, unauthorized opening of the bi-valved cast is
precluded.
The complementary shells of the bi-valved cast may be formed of a
wide variety of materials, the primary requirements being
radiolucense and adequate rigidity without excessive weight.
Aluminum, resin-impregnated fiberglass and plastics are examples of
materials that meet these requirements.
The inflatable liners may be formed of rubber, plastic or other
pliable air impervious material.
The layers of absorbent material which cover the inner walls of the
inflatable liners, may be formed of gauze or sheet wadding, or a
sponge material.
In addition to the means specifically disclosed for releasably
securing the two rigid shells together, a wide variety of
conventional fasteners may be employed, including the non-metallic
fastener sold under the trademark "VELCRO", a product available
commercially, which consists of mating hooked pile fabric.
Although sufficient adhesion normally exists between the inflatable
liners and the rigid shells to preclude relative shifting
therebetween, where it is deemed necessary a suitable adhesive may
be used to assure against such relative shifting.
The pressure in the inflatable liners should be 75 to 95 percent of
diastolic pressure for best results. Such a pressure range provides
substantial immobilization of the encased body portion and yet does
not inhibit or prevent circulation of blood in the arteries and
veins.
Although the operation of the invention is no doubt readily
understood from the foregoing description and the drawings, for
sake of completeness, in applying the cast to a limb, the limb L is
placed in the lower shell 12-12' and then the upper shell 11-11' is
closed upon the limb. After the shells are secured in mating
relationship, air is introduced into inflatable liners through the
inlet valves 20 an 21. A conventional pressure device may be
readily employed to measure the pressure in the liners. The
inflated liners provide a uniform pressure on the immobilized limb
and automatically compensate for any variation in distance between
the shells and the limb. As the limb swells or contracts, the
volume of air in the liners may be varied to maintain the limb
under a constant pressure.
The bi-valved cast may be reused by simple removing and replacing
the layers of absorbent material, following washing of the cast, if
needed.
Those skilled in the art will appreciate that the invention can be
embodied in forms other than as herein disclosed for purposes of
illustration.
* * * * *