U.S. patent application number 16/054948 was filed with the patent office on 2018-11-29 for overmolding for an orthopedic walking boot.
The applicant listed for this patent is OVATION SYSTEMS D/B/A/ OVATION MEDICAL, OVATION SYSTEMS D/B/A/ OVATION MEDICAL. Invention is credited to Ryan C. Cohn, Tim Crowley, Tracy E. Grim, Steven L. Hecker, Kenji Watabe, Veneza Yuzon.
Application Number | 20180338851 16/054948 |
Document ID | / |
Family ID | 51524007 |
Filed Date | 2018-11-29 |
United States Patent
Application |
20180338851 |
Kind Code |
A1 |
Grim; Tracy E. ; et
al. |
November 29, 2018 |
OVERMOLDING FOR AN ORTHOPEDIC WALKING BOOT
Abstract
A method of manufacturing an orthopedic walking boot, comprising
providing a base configured to support a user's foot and receive a
support assembly configured to support the user's lower leg; and
overmolding an outer sole to the base.
Inventors: |
Grim; Tracy E.; (Thousand
Oaks, CA) ; Hecker; Steven L.; (Los Angeles, CA)
; Watabe; Kenji; (Ventura, CA) ; Cohn; Ryan
C.; (Torrance, CA) ; Crowley; Tim; (Ventura,
CA) ; Yuzon; Veneza; (Calabasas, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OVATION SYSTEMS D/B/A/ OVATION MEDICAL |
Agoura Hills |
CA |
US |
|
|
Family ID: |
51524007 |
Appl. No.: |
16/054948 |
Filed: |
August 3, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14214319 |
Mar 14, 2014 |
10039664 |
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16054948 |
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61916077 |
Dec 13, 2013 |
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61801843 |
Mar 15, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29C 45/14008 20130101;
A61F 5/0111 20130101; B29C 2045/1454 20130101; A61F 5/0195
20130101; B29C 45/14467 20130101 |
International
Class: |
A61F 5/01 20060101
A61F005/01; B29C 45/14 20060101 B29C045/14 |
Claims
1. A method for constructing an orthopedic walking boot,
comprising: providing a plantar boot base having a substantially
smooth lower surface; placing the plantar boot base into a mold;
introducing a molten resin material into the mold to form a
overmolded outer sole, the overmolded outer sole covering a lower
surface and peripheral edges of the plantar base, wherein the
molten resin material is selected to chemically bond to the plantar
boot base without adhesive; and connecting a vertically disposed
leg support member to the plantar base.
2. The method for constructing an orthopedic walking boot of claim
1, further comprising forming a plurality of channels on the lower
surface of the plantar boot base, and wherein the molten resin
material fills plurality of channels to add shear strength to a
mating of the overmolded outer sole and the plantar boot base.
3. The method for constructing an orthopedic walking boot of claim
2, wherein a density of channels in the plantar boot base is higher
near a toe portion.
4. The method for constructing an orthopedic walking boot of claim
2, wherein the channels comprise stepped walls.
5. The method for constructing an orthopedic walking boot of claim
1, wherein the plantar boot base is formed from a
polypropylene.
6. A method for constructing an orthopedic walking boot,
comprising: providing a plantar boot base having a substantially
smooth lower surface; placing the plantar boot base into a mold;
introducing a molten resin material into the mold to form a
overmolded outer sole, the overmolded outer sole covering a lower
surface of the plantar base, wherein the molten resin material is
selected to chemically bond to the plantar boot base without
adhesive; and connecting a vertically disposed leg support member
to the plantar base.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation based on U.S. Ser. No.
14/214,319, filed on Mar. 14, 2014, which claims the benefit of
U.S. Provisional Application Ser. No. 61/801,843, filed on Mar. 15,
2013; and 61/916,077, filed on Dec. 13, 2013, each of which is
expressly incorporated by reference herein in their entirety.
BACKGROUND
Field
[0002] The present disclosure relates generally to orthopedic
walking boots.
Background
[0003] It is common that people, especially active and/or frail
people, experience a variety of lower leg and ankle injuries. To
aid in the treatment of the injuries it is desirable to immobilize
the injury, typically above and below the affected joint.
[0004] Physicians traditionally place a patient's leg in a short
leg cast, which is a cast that begins at the patient's toes and
ends below the patient's knee. Generally, casts retain heat, cause
an itching sensation on the skin, and rub against the leg after
swelling of the leg subsides.
[0005] An alternative to the short leg cast is an orthopedic
walking boot, or a premanufactured orthopedic walking boot, that is
made of a rigid plastic frame lined with a soft component (e.g, a
soft padding) to accommodate the leg comfortably. Often, the liner,
or soft component, may house a series of air bladders that can be
adjusted by the patient to improve the fit and help compress the
swelling to reduce pain and increase stability. The orthopedic
walking boots can be removed to treat skin problems, such as, to
remove sutures or conduct passive range of motion exercises. Short
leg casts do not offer the luxury of easy on/off.
[0006] An orthopedic walking boot is primarily a rigid encasing
that envelopes the leg and immobilizes the foot and ankle at a
neutral position (e.g., the foot extends 90 degrees relative to the
leg). The patient can walk easiest if the ankle is fixed at 90
degrees. At angles other than 90 degrees the patient will be
walking on the toes or on the heel. The sole of the foot is
generally curved from front to back in a rocker bottom fashion. The
curvature of the sole provides a smoother stride from front to back
allowing the heel to strike the ground first, followed by a rocking
of foot forward, and finally a push off on the toes for a
successful step.
SUMMARY
[0007] Aspects of a method of manufacturing an orthopedic walking
boot may include providing a base configured to support a user's
foot and receive a support assembly configured to support the
user's lower leg; and overmolding an outer sole to the base.
[0008] Another aspect of a method of manufacturing an orthopedic
walking boot may include providing a base configured to support a
user's foot and receive a support assembly configured to support
the user's lower leg; and integrally forming an outer sole to the
base.
[0009] Another aspect of a method of manufacturing an orthopedic
walking boot may include providing a base configured to support a
user's foot and receive a support assembly configured to support
the user's lower leg, the base comprising a section configured to
support the user's posterior portion of the heel; and overmolding
an outer sole and at least one of a heel cushion and heel bumper to
the base using a single shot process with said at least one of the
heel cushion and heel bumper being arranged with the section.
[0010] Another aspect of a method of manufacturing an orthopedic
walking boot may include providing a base configured to support a
user's foot and receive a support assembly configured to support
the user's lower leg, the base comprising a first section to
protect the forward end of the user's toes and a second section to
support the user's posterior portion of the heel; mating a shock
absorber insert with the base to provide shock absorption to the
user's foot; and overmolding an outer sole, a toe bumper, a heel
cushion and a heel bumper to the base using a single shot process;
wherein at least a portion of the outer sole is overmolded to the
base and the shock absorber insert, the toe bumper is overmolded to
the first section, the heel cushion is overmolded to an interior
portion of the second section, and the heel bumper is overmolded to
the second section with at least a portion of the heel bumper
arranged with an exterior portion of the second section.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a perspective view of an orthopedic walking boot,
in accordance with aspects of the present invention;
[0012] FIG. 2 is an bottom perspective view of a base of the
orthopedic walking boot of FIG. 1, without an outer sole;
[0013] FIG. 3 is cut perspective view of the orthopedic walking
boot of FIG. 1;
[0014] FIG. 4A is a side view of a base of an orthopedic walking
boot in accordance with other aspects of the present invention;
[0015] FIG. 4B is a top perspective view of the base of FIG. 4A
prior to overmolding;
[0016] FIG. 5 is a top perspective view of a base of an orthopedic
walking boot in accordance with other aspects of the present
invention;
[0017] FIG. 6 is a perspective view an orthopedic walking boot, in
accordance with other aspects of the present invention;
[0018] FIG. 7A is a partial perspective view of a base of an
orthopedic walking boot prior to overmolding, in accordance with
other aspects of the present invention;
[0019] FIG. 7B is a partial perspective of the base of FIG. 7A
after overmolding; and
[0020] FIG. 8 is a side view of an orthopedic walking boot, in
accordance with other aspects of the present invention.
DETAILED DESCRIPTION
[0021] Various aspects of the present invention will be described
herein with reference to drawings that are schematic illustrations
of idealized configurations of the present invention. As such,
variations from the shapes of the illustrations as a result, for
example, manufacturing techniques and/or tolerances, are to be
expected. Thus, the various aspects of the present invention
presented throughout this disclosure should not be construed as
limited to the particular shapes of elements (e.g., regions,
layers, sections, substrates, etc.) illustrated and described
herein but are to include deviations in shapes that result, for
example, from manufacturing. Thus, the elements illustrated in the
drawings are schematic in nature and their shapes are not intended
to illustrate the precise shape of an element and are not intended
to limit the scope of the present invention, unless intentionally
described as such.
[0022] It will be understood that when an element such as a region,
layer, section, or the like, is referred to as being "on" another
element, it can be directly on the other element or intervening
elements may also be present. In contrast, when an element is
referred to as being "directly on" another element, there are no
intervening elements present. It will be further understood that
when an element such as a structure is referred to as being coupled
to another element, it can be directly connected to the other
element or intervening elements may also be present. Similarly, two
elements may be mechanically coupled by being either directly
physically connected, or intervening connecting elements may be
present. It will be further understood that when an element is
referred to as being "formed" on another element, it can be
deposited, attached, connected, coupled, or otherwise prepared or
fabricated on the other element or an intervening element.
[0023] Furthermore, relative terms, such as "lower" or "bottom" and
"upper" or "top," may be used herein to describe one element's
relationship to another element as illustrated in the drawings. It
will be understood that relative terms are intended to encompass
different orientations of an apparatus in addition to the
orientation depicted in the drawings. By way of example, if the
orientation of an orthopedic walking boot shown in the drawings is
turned over, elements described as being on the "lower" side of
other elements would then be oriented on the "upper" side of the
other elements. The term "lower", can therefore, encompass both an
orientation of "lower" and "upper," depending of the particular
orientation of the orthopedic walking boot. Similarly, if the
orientation of an orthopedic walking boot shown in the drawing is
turned over, elements described as "below" or "beneath" other
elements would then be oriented "above" the other elements. The
terms "below" or "beneath" can, therefore, encompass both an
orientation of above and below.
[0024] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and this disclosure.
[0025] It will be further understood that the terms "comprises"
and/or "comprising," when used in this specification, specify the
presence of stated features, integers, steps, operations, elements,
and/or components, but do not preclude the presence or addition of
one or more other features, integers, steps, operations, elements,
components, and/or groups thereof. The term "and/or" includes any
and all combinations of one or more of the associated listed
items.
[0026] The detailed description set forth below in connection with
the appended drawings is intended as a description of various
aspects of the present invention and is not intended to represent
all aspects in which the present invention may be practiced. The
detailed description includes specific details for the purpose of
providing a thorough understanding of the present invention.
However, it will be apparent to those skilled in the art that the
present invention may be practiced without these specific details.
In some instances, well-known structures and components are shown
in block diagram form in order to avoid obscuring the concepts of
the present invention.
[0027] Various aspects of the present invention may provide an
orthopedic walking boot that may be fitted around the leg to
provide support and allow ambulation for the affected limb.
[0028] Reference to various ranges may be used to describe certain
aspects of the present invention. By way of example, a range may be
used to describe variations of the bonding force at different
points on an outer sole to describe an evenly distributed bonding
of the outer sole to the base of the orthopedic walking boot. By
way of an example, an outer sole which provides evenly distributed
bonding to the base of the orthopedic walking boot may exhibit a
narrower tolerance band of force values at all x,y coordinates on
the bonding surface than tolerance band of any other attachment
method of the outer sole to the base of the orthopedic walking
boot.
[0029] People often experience injuries to the lower leg and ankle.
For example, blunt trauma, sports injuries and common falls are the
primary causes. Injuries such as fractures of the bones or soft
tissue injuries (e.g., ligamentous tears) have similar symptoms.
Swelling, pain and inability to ambulate without support are
expected and predictable. Some injuries need to be immobilized for
a period of time for the injury to heal. The time required for
ligamentous injuries to heal is similar to the time required for
fractures to heal. A period of 4 to 6 weeks of immobilization is
common. Different injuries require different rehab times and
regimes.
[0030] Aspects of the present invention are directed to orthopedic
walking boots. In an aspect of the prevention invention, an
orthopedic walking boot may include bilateral struts which connect
a base of the orthopedic walking boot to an upper portion of the
orthopedic walking boot. The struts may be rigid and provided on
either side of the leg. The bilateral struts may be held onto the
limb with strapping systems that encircle at least a portion of the
limb. In another aspect, the base may be attached a posterior piece
which extends from the foot to the back of the leg and calf forming
a clamshell configuration. In the clamshell configuration, a single
piece encompasses the side of the leg (similar to the bilateral
configuration) as well as the rear of the leg. The orthopedic
walking boot may include an adjoining anterior piece that joins or
overlaps the posterior piece and is held on by a traditional
strapping system or with mechanical attachment mechanism. In
another aspect, the orthopedic walking boot may comprise a "hybrid"
configuration (also referred herein as a "multi-sectioned"
configuration). In the hybrid configuration, the base may be
attached to the bilateral struts of the bilateral configuration and
also attached a separate/non-integral posterior element that
encompasses the rear of leg (similar to the rear portion of the
clamshell). In this manner, the bilateral struts surround the side
of the legs while the separate posterior portion encompasses the
rear of the leg. Thus, the hybrid configuration achieves a similar
result as the clamshell with multiple sections, hence,
"multi-sectioned."
[0031] In an aspect, the orthopedic walking boot may be configured
such that the portion that receives the user's foot (e.g., the base
portion) extends at 90.degree. degrees or at substantially
90.degree. relative to a longitudinal axis of the portion that
receives the user's leg (e.g., the upper portion). In another
aspect, the orthopedic walking boot may include two struts rising
from the base. The orthopedic walking boot may further include a
soft component within the constraints of the struts and on top of
the base. The soft component may be held by straps.
[0032] The orthopedic walking boot may include an outer sole
overmolded onto the base. Traditionally, the soles of orthopedic
walking boots are die-cut or molded separately from the base into
the shape needed to mate with the base. Traditionally, the outer
sole is then adhered onto the rigid walker by an adhesive.
Traditionally, both the outer sole and the base of the rigid walker
surface are treated with the adhesives. Attaching the separately
formed sole to the base via an adhesive has several problems.
Adhesives can be difficult to apply, have a limited shelf life, are
affected by humidity or temperatures, and have a variety of set
times. Furthermore, it can be difficult to apply additives to all
desired surfaces. Often, there is an over spray of adhesives when
precise metering is difficult. Manufacturers may apply too much
adhesive which results in failed or reduced joining and external
leakage or inconsistent curing. Conversely, insufficient adhesive
can result in failures. The adhesives have to be correctly applied
in a controlled environment for the high shear and peel strength to
be accomplished predictably in a medical grade product.
[0033] Furthermore, there is a growing awareness regarding the
toxicity of many adhesives and for using them in medical products
placed next to the skin or close to wounds and broken skin.
Additionally, it is nearly impossible to thoroughly test the bond
strength when a sole is attached to a base via an adhesive. Since
the outer sole is fully attached to the base, it is impossible to
visually identify where the adhesive is located as compared to
where it is supposed to be. Only destructive testing can provide
the necessary information. Adhesives are often applied manually by
humans, allows for human error.
[0034] The problem of adhesives peeling is of particular concern
for orthopedic walking boots because, unlike footwear, if the outer
sole of an orthopedic walking boot begins to separate from the
base, a patient cannot easily replace or repair it. Because the
orthopedic walking boot protects a fractured leg, a patient is not
able to take the time necessary to remove the orthopedic walking
boot and repair it. Due to the shuffling gait patterns that many
patients initially exhibit, the toe portion of the orthopedic
walking boot walker is placed under long-term extreme shear and
peel forces which are difficult for adhesives to withstand.
Therefore, with adhesives the tip or the toe of the outer sole may
begin to separate during use. Every time the toe shuffles, the soft
outer sole is forced to stretch and deform as compared to the base
it is attached to. As this happens, the separating outer sole may
catch onto the surface the patient is walking upon, which can cause
the patient to trip and fall.
[0035] In an effort to ensure a more aggressive, permanent,
predictable and safe attachment of an outer sole to the base, one
aspect of the present invention includes a method of attaching the
outer sole directly onto the base of the orthopedic walking boot by
overmolding, e.g., without the need for an adhesive. Overmolding
ensures a permanent bond because the process molds the outer sole
under high heat and pressure directly onto the base of the
orthopedic walking boot. No separate adhesive layer is needed
between the outer sole and the base. Overmolding provides a
permanent chemical joining of the two materials such that the outer
sole is integrally formed with the base. This arrangement provides
high peel and shear strength.
[0036] Overmolding is a process of injection molding one material
onto a second (typically rigid plastic) to achieve a combination of
properties (mechanical, aesthetic, etc.) in specific zones, often
resulting in an integral bond between the two materials.
Overmolding is stronger, safer, and more consistent than other
attachment method such as an adhesive, and has a lower long-term
cost. The majority of the overmolding described herein will pertain
to the outer sole of the orthopedic walking boot, i.e., the soft
underside of the orthopedic walking boot that contacts the floor as
the patient walks. In an aspect of the present invention, the
overmolding process includes placing the base into a die (also
referred herein as "mold"). The die may be particularly shaped to
receive the base and to inject molten resin precisely where
desired. Once the base is secured in the die, the molten resin is
injected into the mold and flows around precise portions of the
base. The flow of resin may be restricted by the geometry of the
die. Once the resin hardens, the base, having the outer sole
overmolded onto it, may be removed from the die.
[0037] The outer sole may be overmolded to the base such that the
outer sole is continuous (FIG. 1) or segmented (FIG. 4). The outer
sole may be molded at a different time than the base. In addition,
the base and the outer sole may be molded within a very short
interval of time between each other while the base is still warm,
which in turn can increase the surface acceptance of the outer sole
to the base. The outer sole may be made of a material that is
chemically compatible with the base of the orthopedic walking
boot.
[0038] In an aspect, the outer sole may be applied to the base of
the orthopedic walking boot to ensure a continuous, or near
continuous surface for the patient to pivot upon while turning
during ambulation. Furthermore, a plurality of through-holes may be
distributed on the bottom surface of the base, which is discussed
in more detail below. After the outer sole has been overmolded to
the base, a tool may be inserted and pressed against the inside
surface of the outer sole to determine peel strength and shear
strength. Furthermore, an undercut around the perimeter of the base
may secure the outer sole mechanically from removal in a direction
normal to the base (i.e., a force pulling the outer sole off the
base).
[0039] Another aspect may include overmolding the outer sole onto
an orthopedic walking boot having a bilateral strut configuration,
a clamshell configuration, or a hybrid configuration. The
overmolding provides a safe way to attach the outer sole to the
base of the orthopedic walking boot without using an adhesive to
connect the outer sole to the base. In another aspect, the
orthopedic walking boot may comprise a posterior splint that is
removable and attached to the posterior component of the orthopedic
walking boot. For this type of orthopedic walking boot, overmolding
of the outer sole to the base of the orthopedic walking boot may be
accomplished in the same manner discussed above.
[0040] As discussed above, an aspect of the present invention
includes an orthopedic walking boot with an outer sole that is
bonded to the base of the orthopedic walking boot without an
adhesive. FIG. 1 illustrates an orthopedic walking boot 100 with an
outer sole 104 which may be overmolded to the base 102 of the
orthopedic walking boot 100. The outer sole may be elastomeric. The
orthopedic walking boot 100 may include a support assembly 106. The
support assembly 106 shown in FIG. 1 is the bilateral type.
However, the orthopedic walking boot may have support assemblies
consistent with the clamshell or hybrid types discussed above.
[0041] FIG. 1 illustrates an outer sole 104 that may completely
cover the bottom surface of the base 102, and in particular,
portions of the base 102 that contact the ground during use. The
outer sole 104 may extend up the sides of the perimeter of the
walker base 102 to maximize surface contact between the outer sole
104 and the base 102. In an aspect, the outer sole 104 may comprise
a thermoplastic elastomer bonded by overmolding to the base 102.
The base 102 may comprise a rigid polypropylene material.
Alternatively, a number of different material pairs may be bonded
in a similar manner, as long as they are chemically and thermally
compatible. The bottom surface of the outer sole 102 may include
tread 103 formed during the overmolding process. Various tread
patterns may be applied by using a series of inserts in the
overmold tool, where each insert is designed aesthetically or
otherwise, to provide a different appearance of the tread while
maintaining the desired physical properties, e.g., water
channeling, grip on slippery surfaces, etc. Furthermore, the
longitudinal axis of the outer sole 104 may be defined as the axis
along the direction from the heel of the outer sole 104 to the toe
of the outer sole 104. The outer sole may further include apertures
107 formed during the overmolding process similar to the tread.
[0042] FIG. 2 is shows a bottom perspective view of the base 102 of
the orthopedic walking boot prior to overmolding the outer sole
onto the base. FIG. 2 illustrates one aspect of the base 102 which
utilizes a plurality of fastening techniques to secure the outer
sole to the base 102 via overmolding. The base 102 may include a
substrate section 112 having a substantially smooth surface. The
smooth surface facilitates flow of the outer sole resin material
longitudinally from front to back (e.g., heel to toe) during the
overmolding process. The smooth quality of the base substrate
section 112 has a low surface roughness which allows for less
turbulence in the resin at the substrate surface, allowing for the
superior surface adhesion. The chemical bond between the substrate
and the overmolded material in this case represents a high peel
strength type of adhesion.
[0043] The base 102 may include first blind holes 114 passing
partially through the thickness of the base substrate section 112.
In another aspect, the holes 114 may be through holes that pass
entirely through the base 102. As shown in FIG. 2, the geometry of
the blind holes 114 may be rectangular. The blind holes 114,
passing partially through the thickness of the base substrate,
allow the outer sole resin material to fill into the holes during
the overmolding process and chemically bond to the inside surface
of holes. As shown in FIG. 2, the blind holes 114 may be disposed
adjacent the periphery of the substrate section 112. The blind
holes 114 may have a substantially rectangular shape that extends
in the direction of the flow of the outer sole resin material
during the overmolding process (e.g., in a direction from heel to
toe). When the resin material adheres to the inside surface of the
blind holes 114 it creates a shear-type connection to the base.
This connection is a significantly stronger type of bond than a
peel-type bond that adhesion alone would provide.
[0044] The geometry of the blind holes 114 required to provide an
adequate shear bond is not limited to a rectangular geometry
described above and is only one of a number of appropriate shapes
that will provide the proper bond. The particular geometry may
depend on the flow characteristics of the selected overmolding
resin, and may include stepped walls, circular or non-circular
holes, and/or other geometry. Orientation of the hole geometry with
respect to the surrounding geometry of the orthopedic walking boot
may be determined by the loading conditions anticipated in a
particular area. Specifically, in an aspect, the holes may include
linearly extending holes at varying angles relative to the primary
axis extending along the length of the orthopedic walking boot
(i.e., from heel to toe). The linear holes may provide strength to
the overmold in an area of the base where patients drag or rotate
more than in other zones, thus providing an elevated amount of
applied stress to the overmolded outer sole in that area.
[0045] Similarly, the spacing from one hole to another may vary
depending on the manner in which the orthopedic walking boot is
used. The spacing may be determined based upon use patterns (e.g.,
a pattern that indicates which portion of the sole has heavier wear
during use of the orthopedic walking boot). For example, the
placement of linear holes may be denser in areas of base that
correspond to portion of the sole that experience higher stress
during uses. Additional aspects may include linear holes that are
less densely distributed in areas of the base where peel adhesion
alone is sufficient, while having a higher density of linear holes
in areas of the base where more wear occurs.
[0046] It should also be noted that in other types of plastic
molding, a generally accepted practice of "steel-safe" design can
reduce the risk that pairs of parts intended to mate fit correctly,
by adjusting the sizing after the mold has been tested. The shear
features as described above make use of this principle, by
reserving appropriate real estate such that additional shear holes
may be added if testing shows the need for a more secure bond.
[0047] The base 102 may further include second blind holes 116 that
perform a similar function of a providing a shear-type bond when
the overmold resin flows over the surface of the base. The series
of second blind holes 116 in the base (for example at the toe
section as shown) similarly do not pass entirely through the base
substrate 112, and therefore do not need to be shut off by the
steel on the core side of the injection mold at the opposite side
as the holes 116. In addition, the density of the blind holes 116
creates a locally stronger shear-type bond while maintaining the
strength of the base substrate 112 in this area. The high density
of these shear features is useful in the particular region shown,
because the region near the toe exhibits a relatively high amount
of wear when high mobility patients drag the toe of the orthopedic
walking boot, or shuffle aggressively, for example. The specific
geometry and spacing may be optimized based on the flow
characteristics of the resin being injected. The specific geometry,
spacing and orientation of the shear feature shown in FIG. 2 is one
possible configuration, which may address unique concerns in
specific zones of the walker, including high wear or areas of more
frequent impact, etc. Those skilled in the art may derive similar
configurations for geometry, spacing and orientation that address
similar concerns.
[0048] Referring to FIG. 2, the base 102 may include through holes
or apertures 118 which pass entirely through the base. The through
holes 118 increase in diameter or overall cross section at an
elevation away from the bottom surface of the base and into the
base substrate 112. The resulting geometry of the hardened resin
creates a physical interference or interlock which resists
separation of the outer sole from the base. Thus, the physical
interference serves a similar function as a nail used to secure a
sole to a base.
[0049] FIG. 3 shows a cut view of the base 102 of the orthopedic
walking boot after the outer sole 104 has been overmolded onto the
base 102. As best seen in FIG. 3, the base 104 may include a
section 125 configured to support the user's posterior portion of
the heel. FIG. 3 shows through holes 118 providing the entry point
of the molten overmold material resin on the bottom surface side of
the orthopedic walking boot 100. FIG. 3 further shows one example
of the interlock 120 between the base 102 and the outer sole 104.
For example, as shown in FIG. 3, a portion of the outer sole (i.e.,
a portion of the resin) extends from an outer surface of the base
102 into an inside surface of the base 102, thereby forming the
interlock 120. This interlock 120 serves a similar function as a
nail.
[0050] While FIGS. 2 and 3 show several example locations of
through holes 118 (and thus locations of the mechanical interlocks
120 after overmolding), the through holes 118 can vary and size and
position. It should also be noted that the larger cross section of
the mechanical interlock feature 120, as compared to the throat,
does not have to rest entirely above the wall of the base substrate
102. It may be configured such that the hole in the base substrate
102 is a chamfered hole, with the larger part of the resin still
captured within the thickness of the wall section, such feature not
needing to emerge above the floor of the base substrate 102 since
the mechanical interlock is contained entirely within the thickness
of the wall.
[0051] In an aspect, the outer sole may have a variety of colors by
changing the color of the overmold resin in the hopper of the
injection molding machine. This may be done on demand thereby
reducing the need to inventory many outer soles as would be
necessary if the soles were molded as a separate part that is then
mechanically or adhesively attached to the base at a later time.
This results in more flexibility of inventory and just-in-time
manufacturing and lower ultimate cost.
[0052] As shown in FIGS. 2 and 3, the base 104 may include a pocket
150 (FIG. 2) for receiving a shock absorber insert 122 (FIG. 3).
The perimeter of the pocket 150 may be defined by a receiving
channel 152. The channel 152 is configured to receive a lip 124 of
the shock absorber insert 122. The orthopedic walking boot may
further include the shock absorber insert arranged with the base
and the outer sole to provide shock absorption. The shock absorber
insert may be arranged along a section of the base configured to
support the user's plantar portion of the heel. As shown in FIG. 2,
several of the through holes 118 may be disposed in pocket 150 of
the base 104. These apertures located at the pocket may cooperate
with corresponding through holes of the shock absorber insert. In
another aspect, the through holes may not be present in the pocket
area, in which case a shock absorber insert may be adhered within
the pocket via an adhesive. The base portion in the pocket area may
further include posts (not shown) extending from the underside
surface of the base and extending in a direction toward ground/away
from the bottom of the users foot. Similarly, the shock absorber
insert may include corresponding receiving portions to mate with
the posts. The mating of the posts with the receiving portions
provide further stability of the shock absorber insert within the
pocket.
[0053] In an aspect, the outer sole may comprise a first durometer,
and the shock absorber insert may comprise a second durometer lower
than the first durometer of the outer sole. For example, the shock
absorber insert may have a Shore A durometer of 30 while the outer
sole may have a Shore A durometer of 60.
[0054] In another aspect, as shown in FIGS. 1 and 3, the orthopedic
walking boot may include a heel cushion 105. In another aspect, as
shown in FIG. 4A, the base 302 may include a heel cushion 305 and a
heel bumper 306. The heel bumper may protrude from the heel portion
310. In an aspect, the heel portion of the base may have an
aperture 312 extending through the thickness of the heel and
communicating with a connective tunnel 314 that extends to the
bottom surface of the base. FIG. 4A shows the resin material filled
in the aperture 312 and the connective tunnel 314. FIG. 4B shows
the base 302 prior to the molding process. As shown in FIG. 4B,
prior to the molding process, the connectives tunnel 314 would not
contain the solidified resin.
[0055] As noted above, the base 104 may include a section
configured to support the user's posterior portion of the heel. In
an aspect, the heel cushion 105 may extend along an interior
portion of the section of the base configured to support the user's
posterior portion of the heel. The molding of the outer sole and
heel cushion may be performed such that the outer sole and the heel
cushion comprise a continuous material overmolded to the base. In
this case, the connective tunnel formed in the heel portion of the
base provides a passageway for the resin to flow up the connective
tunnel and solidify into the heel cushion. In another aspect, the
outer sole and the heel bumper comprise a continuous material. In
this case, the resin flows up the connective tunnel, into the
aperture, and the hardened resin will form the bumper. In another
aspect the outer sole, the heel cushion, and the heel bumper
comprise a continuous material. In this case, the resin would flow
up the connective tunnel to form the heel cushion and through the
aperture to form the bumper.
[0056] Furthermore, the heel cushion may extend along the interior
portion of the section of the base configured to support the user's
posterior portion of the heel. FIG. 5 shows a top perspective view
another aspect of the present invention of a base 404 having a heel
cushion 402 extending to the left and right lateral sides 406 of
the base 404. A rear section (also referred herein as "distal
section") of the base 404 is shown in a configuration where the
soft heel cushion 402 extends to the left and right lateral sides
406 of the inside of the base 404, providing additional cushion for
patient physiology. In other words, the heel cushion may be
arranged with a section of the base to engage the user's posterior
portion of the heel and may wrap around a distal end of the section
of the base. The heel cushion may also extend along an interior
portion of the section of the base between distal and proximal ends
thereof.
[0057] Aspects of the present invention include a method of
manufacturing an orthopedic walking boot. The base may be formed
through injection molding by injecting a first material into a
mold. Next, the outer sole may be overmolded on the base. The base
may be provided within a mold, and the overmolding of the outer
sole may include injection a material into the mold and allowing
the material to form to the base. The overmolding of the outer sole
may include injecting a second material into the mold and allowing
the second material to form to the base. The shock absorbing insert
may be overmolded to the base. In an aspect at least a portion of
the outer sole is overmolded to the base through the shock absorber
insert. The method may include overmolding a heel cushion to an
interior portion of heel of the base. The outer sole and the heel
cushion may comprise a continuous material overmolded to the base
using a single shot process. Additionally, the outer sole and the
heel bumper may be overmolded to the base using a single shot
process.
[0058] In another aspect, the outer sole may be non-continuous.
FIG. 6 is a perspective view of an orthopedic walking boot 200
comprising of an outer sole overmolded in a plurality of overmolded
sections 202, 204. By forming the outer sole in discrete sections,
different materials can be used for each section, and therefore,
different properties can be exhibited. For example, the different
materials may have different colors, strengths, rigidity, grip,
durometers, and the like.
[0059] To overmold two different sole sections, several methods may
be used, including dual shot molding, where one material is molded
onto the substrate, after which a second injection molding cavity
is shuttled into position, and a second material is injected to be
in contact with the substrate as well as the previously overmolded
material. In another process, co-molding, the first material is
shot into the mold containing the rigid substrate, while a movable
part of the tool prevents material from entering a certain area.
Once material is cured, the movable section of the tool changes
position, and a new material is injected into the newly formed
void, making bonding contact with the rigid substrate as well as
the previously shot material. In a further aspect, two separate
overmold tools are utilized.
[0060] In a further aspect, an outer sole section with one of the
desired material properties (such as high-grip) is molded
separately, and is placed against the substrate in the overmold
tool. When the second material is injected into the mold, it bonds
to both of the substrates that are in the tool. The result is an
outer sole with two separate material properties.
[0061] FIG. 7A is a partial perspective view of a base 502 of an
orthopedic walking boot, prior to overmolding the outer sole to the
base 502. As shown in FIG. 7A, prior to overmolding the outer sole
to the base 502, the portion of the base 502 that protects the toe
of the user during use may include a plurality of through holes
504. The plurality of through holes may extend entirely through the
base 502. The through holes 504 may be separated from each other by
a plurality of separators 506. As shown in FIG. 7A, the separators
506 may be disposed on top of the surface of the base that the
through holes 504 extend through, Thus, the through holes reside is
a smaller thickness portion 308 of the base relative to the
separators 506. During overmolding of the outer sole, a portion of
the resin material will flow through the through holes 504 an fill
in the reduced thickness portion 508. FIG. 7B is a partial
perspective view of the base 502 after overmolding the outer sole
to the base 502. As shown in FIG. 7B, after overmolding, the base
502 may include a toe bumper 510. The toe bumper is formed when the
molten resin material flows through the through holes 504, fills
the reduced thickness portion 508, and then hardens. Thus, the toe
bumper 510 may be overmolded on to the base. In an aspect, the toe
bumper 510 can be overmolded onto the base separately or at the
same time as overmolding the outer sole onto the base. When the
resin of the outer sole passes through the through holes to form
the toe bumper, the toe bumper is continuous with the outer sole.
The method of manufacturing the orthopedic walking boot may include
overmolding a toe bumper to a toe protecting section of the base.
The outer sole and the toe bumper may be overmolded to the base
using a single shot process.
[0062] The through holes in the toe protecting section of the base
that allows for the toe bumper to be overmolded onto the base may
also be applied to any of the aspects described above. For example,
the through holes may be provided in the base shown in FIG. 2.
Accordingly, by using a base having the holes for bonding the resin
material to form the outer sole, the connective tunnels to allow
the resin to form the heel cushion, the aperture through the heel
portion to allow the resin to form the heel bumper, and the holes
in the toe portion to allow the resin to form the toe bumper, one
can form all of the outer sole, heel cushion, the heel bumper, and
the toe bumper with a continuous material and with a single
injection.
[0063] FIG. 8 shows a base 600 of an orthopedic walking boot having
a strap fastener 602, 604 and heel cushion 608. The strap fasteners
602, 604 have a region of overmolding directly adjacent to the
strap holding feature. This boundary includes a region made with a
material having a substantially lower modulus of elasticity, and
allows for flexible controlled movement that would not be provided
with other means of geometry. The strap fasteners 602, 604 may be
fabricated separately to include an overmolded flexible zone, and
then attached via conventional means including adhesives, fasteners
etc. The use of the overmolding material elsewhere in the
orthopedic walking boot allows for the use of flexible material in
the area of the strap connectors 602, 604. FIG. 8 includes a
blown-up portion of the strap connector 602. As shown in FIG. 6,
overmolding 612 surrounds the strap fastener 602. Strap fastener
604 may comprise a different structure than strap fastener 602.
[0064] In addition, other elements of the orthopedic walking boot
may be fastened by engagement or encapsulation with a soft
overmolded material which may be used elsewhere in the design.
These features may be parts or assemblies that are not intended to
be removed and may be connected via conventional fastening methods.
By way of example, FIG. 8 shows an orthopedic walking boot with an
overmolded outer sole featuring a rigid insole, said insole
assembled permanently to the rigid base by the interference created
between the softer overmold material originating from the outer
sole of the orthopedic walking boot, as the outer sole overmold
material is channeled up through tunnel features in the rigid base
to engage with the insole part.
[0065] In an aspect of the present invention, prior to overmolding,
a piece of plastic softer than the base may be adhered to the
bottom surface of the base. The base with or without the added
softer plastic piece may then be placed inside a steel injection
molding tool that has been preheated to an operating temperature
that will facilitate the flow of the resin. One half of the
injection molding tool comprises the cavity. When the tool is in
the closed position in captures the base and holds it securely
under pressure at predetermined locations. The pressure being
applied particular locations serves to confine the resin material
to the proper locations, and also may prevent deflection of
portions of the base geometry that would otherwise occur due to the
high pressure necessary inside the mold to push the molten resin
throughout the tool. The cavity also defines the volume of space
where the overmold material is desired.
[0066] After the mold is closed, the molten resin is injected into
the mold with a specific injection speed and injection pressure
(also referred herein as the injection cycle). The injection
pressure is then held for a period of time while cooler liquid is
circulated through pipes inside the steel adjacent to, but not in
contact with the resin itself. Next, the cavity part of the tool
moves to an open position where the base, with resin overmolded
onto it, is ejected from its position in the tool (also referred
herein as the ejection cycle).
[0067] The particular combination of injection speed and injection
pressure has a direct impact on the properties of the final molded
product such as bond strength, aesthetics, and surface geometry.
For example, the resin can be heated to a particular temperature to
facilitate the correct flow of the molten resin when inside the
mold.
[0068] With respect to bond strength, the injection speed and hold
time, and injection pressure may be chosen to ensure optimal bond
strength between the base and the overmolded resin. Another aspect
that that affects the bond strength is the surface finish of the
finish bottom of the base, which may be optimally polished. For
example, the bottom surface of the base (for example substrate
section 112 shown in FIG. 2), may have a polish of at least B-2 as
determined by Society of the Plastics Industry (SPI)
Guidelines.
[0069] Additionally, the location of the injection gate in the tool
is a factor that affects the minimum level in turbulence
experienced by the resin as it fills the mold.
[0070] With respect to aesthetics, maintaining specific overmold
parameters can avoid poor aesthetics. If the hold pressure of the
overmold process is insufficient, visible surfaces overmold
surfaces may become wavy or bumpy. If the injection and hold
pressures are beyond certain limits, the overmold may travel past
the intended boundaries, resulting in an inferior product. Also,
careful monitoring of the temperature of the barrel of the
injection machine will prevent excessively heated resin from
causing thin portions of the base to detach and/or melt, would
result in visible discoloration to the overmold.
[0071] The operating parameters may vary depending on the
particular size of the base being used in the mold. The following
example parameters are for a thermoplastic elastomeric. Example
injection temperatures may include 23.degree. C. to 25.degree. C.
Example cycle times may include 85 seconds to 88 seconds. Example
pressure may include 45 Mpa to 80 Mpa. Example injection speeds (as
percent of max speed) may be 43% to 78%. Example temperatures of
the barrel may include 210.degree. C. to 215.degree. C.
[0072] When including the shock absorber insert in the orthopedic
walking boot, additional steps may be performed. The shock absorber
insert is first mated with the pocket of the base as described
above. This assembly may occur in the cavity of the molding tool
such that fingers pass through voids in the base to push against
inside surfaces of the shock absorbing insert. The steel fingers
perform the function of keeping the shock element in position
without collapsing under the pressure of the injected resin.
[0073] The claims are not intended to be limited to the various
aspects of this disclosure, but are to be accorded the full scope
consistent with the language of the claims. It is noted that
specific illustrative embodiments of the invention have been shown
in the drawings and described in detail hereinabove. It is to be
understood that various changes and modifications may be made
without departing from the spirit and scope of the invention. All
structural and functional equivalents to the elements of the
various aspects described throughout this disclosure that are known
or later come to be known to those of ordinary skill in the art are
expressly incorporated herein by reference and are intended to be
encompassed by the claims. Moreover, nothing disclosed herein is
intended to be dedicated to the public regardless of whether such
disclosure is explicitly recited in the claims. No claim element is
to be construed under the provisions of 35 U.S.C. .sctn. 112, sixth
paragraph, unless the element is expressly recited using the phrase
"means for" or, in the case of a method claim, the element is
recited using the phrase "step for."
* * * * *