CA2719771A1

CA2719771A1 - Ankle foot orthosis

Info

Publication number: CA2719771A1
Application number: CA2719771A
Authority: CA
Inventors: Gerry J. Sawatsky
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-10-26
Filing date: 2010-10-26
Publication date: 2012-04-26

Abstract

An ankle foot orthosis comprising: a cuff for securement around a user's ankle, and an elastic component comprising an attached first end and a second end;
wherein the elastic component has an inherent bias to assume a condition in which a distance between the first end and the second end is an unextended length; wherein when tension is applied to the elastic component against the inherent bias, the distance between the first end and the second end increases to an extended length, and the inherent bias attempts to return the elastic component to the unextended length; wherein the first end of the elastic component is permanently fastened to the cuff at the front of the user's ankle; wherein the second end of the elastic component is fastened to a vamp of a footwear garment being worn on the user's foot at a location above the user's foot and closer to the user's toes than to the user's ankle.

Description

Title ANKLE FOOT ORTHOSIS
Scope of the Invention [0001] The present invention relates to orthotics, and in particular, to an ankle foot orthosis for correcting foot drop symptoms.

Background of the Invention [00021 Foot drop is a condition where a person has a limited ability or an inability to raise his or her foot at the ankle joint due to weakness or paralysis of the muscles that lift the foot. This leads to difficulty in walking. When the user raises his or her foot to take a step, the toes tend to drag on the ground or the person must use their hip muscles to exaggerate lifting the foot above the ground.
[0003] Foot drop may be caused by muscle or nerve damage, muscle or nerve disorders, or central nervous system disorders. For example, an injury to the muscles that control the ankles and toes can cause foot drop. As another example, disorders that affect the spinal cord or brain, such as amyotrophic lateral sclerosis (ALS) or stroke, may cause foot drop. In addition, foot drop may be an unwanted side effect of various medications, including some chemotherapy drugs used to treat cancer and some drugs used to treat multiple sclerosis.
[0004] Ankle foot orthoses (AFO) are known devices which are used to remediate foot drop symptoms.
100051 Known ankle foot orthoses include large splints which extend from the top of the user's calf down to the back of the heel and forward to the middle of the foot or to the toes.
Examples of such splints are taught in U.S. Patent No. 6,827,696 to Maguire and U.S. Patent No. 7,270,644 to Ingimundarson. These splints lock the ankle joints so that the sole of the foot is kept perpendicular to the tibia axis, and prevent the toes from dragging on the ground.
Such splints are uncomfortable and heavy, making it cumbersome to walk. These splints are also large and unsightly, thus drawing attention to the user's foot drop condition. These splints are generally not bendable, and therefore, prone to breakage.

[0006] Many known ankle foot orthoses require professional fitting procedures, which includes taking impressions of the affected foot to be used in manufacturing a custom sized and shaped ankle foot orthosis. Such professional fittings procedures are costly and there is a delay between the fitting and the user receiving the ankle foot orthosis.
[0007] Many ankle foot orthoses also require the use of customized shoes. Such customized shoes are costly, and do not allow users to buy conventional shoes.
Summary of the Invention [0008] To at least partially overcome the disadvantages of previously known ankle foot orthoses, the present invention provides a new ankle foot orthosis.
[0009] An object of the present invention is to provide a new ankle foot orthosis to correct foot drop symptoms.
[0010] Another object of the present invention is to provide an ankle foot orthosis which is comfortable to wear and light in weight.
[0011] A further object of the present invention is to provide an ankle foot orthosis which is durable and washable.
[0012] Yet another object of the present invention is to provide an ankle foot orthosis which is relatively small in size and discrete.
[0013] Another object of the present invention is to provide a ankle foot orthosis which is inexpensive and which can be transferred from one piece of footwear to another without any difficulty.
[0014] A further object of the present invention is to provide an ankle foot orthosis which can be used with conventional shoes, boots, slippers and sandals.
[0015] Another object of the present invention is to provide an ankle foot orthosis which does not require the user to have a professional fitting.
[0016] The present invention provides a novel ankle foot orthosis. In one aspect, the present invention provides an ankle foot orthosis for correcting foot drop symptoms.
[0017] The ankle foot orthosis comprises a cuff for securement around a user's ankle, and an attached elastic component comprising a first attached end and a second closed-hook end; wherein the elastic component has an inherent bias to assume a condition in which a distance between the first end and the second end is an unextended length;
wherein when tension is applied to the elastic component against the inherent bias, the distance between the first end and the second end increases to an extended length, and the inherent bias attempts to return the elastic component to the unextended length; wherein the first end of the elastic component is fastened to the cuff at the front of the user's ankle; wherein the second end of the elastic component is fastened to a vamp of a footwear garment being worn on the user's foot at a location above the user's foot and closer to the user's toes than to the user's ankle.
[0018] The angle between the sole of the user's foot and an axis of the user's tibia is referred to as a drop angle. Preferably, the elastic component is in a condition without tension when the drop angle is less than 90 degrees, and the elastic component is first placed in a condition under a tension when the drop angle is an initial tension angle in the range of 90 degrees to 100 degrees.
[00191 Preferably, when the user lifts his or her foot above the ground with the user's tibia generally vertical and the user's foot is relaxed, an equilibrium condition occurs in which the inherent bias of the elastic component equals a force required to support the foot and the drop angle is an equilibrium angle of 90 degrees.
[00201 Preferably, the inherent bias prevents the drop angle from exceeding a maximum angle of 135 degrees.

[0021] The initial tension angle is more preferably about 90 degrees. The equilibrium angle is more preferably in the range of 90 degrees to 100 degrees, and more preferably about 90 degrees.
[0022] Preferably, the cuff is wrapped securely around the user's ankle so as to conform to the size and shape of the user's ankle. The cuff is engaged around the ankle to resist sliding downwardly relative to the ankle.
[0023] Preferably, the cuff may be a panel which wraps around the user's ankle. The panel has two ends, such that when the panel is wrapped around the user's ankle, one end is secured to the other end to form a closed loop.

[00241 The first end of the panel may, for example, be secured to the second end of the panel using a velcro hook and loop fastener. A fabric hook section is present on the first end of the panel and a fabric loop section is present on the second end of the panel. When the fabric hook section and the fabric loop section are pressed together, hooks in the fabric hook section catch loops in the fabric loop section to secure the first end and the second end together.
[00251 The panel may be made of many different types of materials, such as an elastomer or a textile. Preferred textiles are cotton, polyester, acrylic, nylon, spandex and blends thereof.
[00261 The cuff preferably has an outer layer and an inner layer. For example, the cuff may have an outer layer comprising an elastomer or a textile and an inner layer comprising a padding material selected from the group consisting of foam, felt, and neoprene.
[00271 The elastic component may be, for example, an elastic band, an elastic cord or a shock cord.
[00281 The first end of the elastic component is preferably permanently fastened to the cuff at the front of the user's ankle by sewing, gluing or heating the elastic to the cuff.
[00291 The permanently fastened end of the elastic component is preferably protected by a grommet that surrounds the elastic at the outer surface. The grommet may be made from plastic or metal.
[00301 The second end of the elastic component is preferably fastened to the vamp of the footwear garment by a snap hook. The snap hook may have a spring-loaded closure.
Preferably, the snap hook is attached to the laces on the footwear garment.
Alternatively, this snap hook may be attached to a closed loop or a closed band which is part of the footwear garment. Alternatively, this snap hook may be attached to one or more holes in the footwear garment.
[00311 The second end of the elastic component preferably fastens to the vamp at a location proximal to or at the user's toes.
[00321 The footwear garment to be used with the ankle foot orthosis of the present invention is preferably a shoe, a boot, a sandal, a slipper or a sock.

Brief Description of the Drawings [0033] Further aspects and advantages will become apparent from the following description taken together with the accompanying drawings in which:
[0034] Figure 1 is a perspective view of an ankle foot orthosis in accordance with a preferred embodiment of the present invention.
[0035] Figure 2 is a partial perspective view of the ankle foot orthosis shown in Figure 1 when applied to a user wearing a conventional shoe.
[0036] Figure 3 is a side view of the ankle foot orthosis applied to a user wearing the conventional shoe shown in Figure 2.
[0037] Figure 4 is a side view of the ankle foot orthosis applied to a user wearing the conventional shoe shown in Figure 2 when the user's foot is resting flat on a horizontal surface.

[0038] Figure 5 is a side view of the ankle foot orthosis applied to a user wearing the conventional shoe shown in Figure 2 when the user lifts his or her foot above the horizontal surface to take a step.

[0039] Throughout all the drawings in the disclosure, similar parts are indicated by the same reference numerals.

Description of the Preferred Embodiment [0040] Reference is made to Figures 1 to 5 which show a preferred embodiment of the present invention.
[0041] Figure 1 illustrates a preferred embodiment of the present invention.
The ankle foot orthosis 10 includes: a cuff 12 which is to be secured around a user's ankle; and an elastic component 14.

[0042] The cuff 12 is a panel which is generally rectangular in shape.
Preferably, the cuff 12 is about 15 cm to 40 cm long and about 8 cm wide, which allows for wrapping the cuff 12 around ankles of many different sizes.
[0043] The cuff 12 has an outer surface 70 and an inner surface 72. When wrapped around an ankle, the outer surface 70 faces outwards and away from the ankle, while the inner surface 72 faces inwards and is in direct contact with the ankle, with or without a sock wrapped around the ankle.
[0044] The cuff 12 has a first end 16 and a second end 18. The first end 16 has a fabric hook section 20 on the outer surface 70 of the cuff 12. The second end 18 has a fabric loop section 22 on the inside of the extended outer surface 70 of the cuff 12.
[0045] When in use, the cuff 12 is wrapped around the user's ankle. The fabric hook section 20 on the first end 16 is pressed together with the fabric loop section 22 on the second end 18, such that the hooks in the fabric hook section 20 catch in the loops in the fabric loop section 22, thus securing the two ends 16, 18 to each other, and forming a closed loop around the ankle. The cuff 12 is wrapped securely around the user's ankle such that is resists sliding above the ankle and resists sliding below the ankle.
[0046] Any portion of the fabric hook section 20 can be pressed together with any portion of the fabric loop section 22 to secure the cuff 12 around the user's ankle. This allows the length of the cuff 12 to be adjusted to ankles of many different sizes.
[0047] The cuff 12 can be made from many different types of materials. For example, the cuff 12 may be made of conumn textile materials such as cotton, polyester, acrylic, nylon, neoprene and blends thereof. The cuff 12 may also be made of stretchable textile materials such as spandex. Alternatively, the cuff 12 may be made of an elastomer.
[0048] The cuff 12 is preferably padded. For example, the cuff 12 may have an outer layer and an inner layer. The outer layer can be made, for example, from any of the different textile materials described above. The inner layer can be made from foam to provide padding. The foam may be a closed cell structured foam, such as a compressible closed cell foam neoprene, or an open cell structured foam, such as an open cell polyurethane.

[0049] The padded inner layer will be wider by 4 to 5 cm to allow for comfort and to prevent slippage on the ankle.
[0050] The inner layer preferably has a thickness of about 3 to 5 mm. The outer layer preferably has a thickness of about 1 to 2 mm.
[0051] The elastic component 14 can be an elastic band, elastic cord, or shock cord such as a bungee cord.
[0052] The elastic component 14 is protected by a grommet 24 that is permanently fastened to the outer surface 70.
[0053] The grommet 24 can be made of many different types of materials, such as plastic or metal.
[0054] There is a fastener 32 at a second end of the elastic component 14.
[0055] The preferred fastener 32 is a snap hook with a closed gate 36. The fastener 32 is to be attached to the vamp of a footwear garment being worn on the user's foot.
[0056] The fastener 32 can be made of many different types of materials, such as plastic or metal.
[0057] Figures 2 and 3 illustrate the preferred ankle foot orthosis 10 when applied to a user. The cuff 12 is wrapped around the user's ankle 50. The fabric hook section 20 on the first end 16 of the cuff 12 is pressed together with the fabric loop section 22 on the second end of the cuff 12 to secure the two ends 16, 18 to each other and to form a closed loop around the ankle 50. Any portion of the fabric hook section 20 can be pressed together with any portion of the fabric loop section 22, allowing the user to adjust the length of the cuff 12 so as to form a snug fit which conforms to the size and shape of the ankle 50.
The snug fit helps to prevent the cuff 12 from sliding above the ankle 50 or below the ankle 50.
[0058] The cuff 12 can be wrapped so that it is in direct contact with the skin around the user's ankle 50. Alternatively, the cuff 12 can be wrapped over a sock worn by the user and around the user's ankle 50.
[0059] Preferably, the cuff 12 has an inner layer of foam padding inside an outer layer of textile to provide cushioning.

[0060] In the preferred embodiment illustrated in Figures 2 and 3, the user is wearing a conventional shoe 60. The shoe 60 has a vamp 62 with two parallel rows of holes 64. The two parallel rows of holes 64 extend from a location proximal to the front of the ankle to a location proximal to the toes. A lace 66 is threaded through the two parallel rows of holes 64 in a crisscross configuration with the two ends of the lace 66 extending out the top pair of holes closest to the user's ankle. The user ties the two ends of the lace 66 together.
[0061] The elastic component 14 is attached to both the cuff 12 and the shoe 60.
[0062] The user pushes the spring-loaded closure 36 of the fastener 32 inwards to open it.
The fastener 32 is hooked around lace 66 on the vamp 62 of the shoe 60. The user releases the closure 36 so that it closes, thus forming a secure attachment between one end of the elastic component 14 and the lace 66 on the shoe 60. Preferably, the fastener 32 attaches to the lace 66 at the bottom pair of holes 64 which are closest to the user's toes.
[0063] In alternative embodiments, the ankle foot orthosis 10 of the present invention can be used with any other type of footwear garment, including boots, slippers, sandals and socks.
[0064] In one alternative embodiment, the fastener 32 can be attached to the laces of a boot, slipper or sandal. In another alternative embodiment, the fastener 32 can be attached to a closed ring or closed band, where the ring or band is part of a shoe, boot, slipper or sandal.
In yet another alternative embodiment, holes can be punched, drilled or cut into the vamp of a shoe, boot, slipper, sandal or sock to allow the fastener 32 to attach thereto.
[0065] As illustrated in Figures 4 and 5, when the ankle foot orthosis 10 of the present invention is applied to the user, the user's foot drop symptoms are corrected.
Without the ankle foot orthosis 10, the user would only have a limited ability or an inability to raise his or her foot at the ankle joint. As such, when the user raises his or her foot to take a step, the user's toes will tend to drag on the ground. When the ankle foot orthosis 10 is applied to the user, such foot drop symptoms are corrected.
[0066] As shown in Figure 4, before taking a step, the user's foot 200 rests flat on the ground 100. The ground 100 prevents the user's foot 200 from dropping about the user's ankle 50. There is a drop angle D of 90 degrees between the sole of the user's foot 200 and the axis of the user's tibia 300. This is the initial tension angle where the elastic component 14 is first placed in a condition under tension and there is no slack.
[0067] As shown in Figure 5, when the user lifts his or her foot above the ground 100 to take a step with the user's tibia 300 generally vertical and the user's foot 200 is relaxed, the user's foot 200 will begin to drop at the toes. When this drop occurs, an equilibrium condition occurs in which the inherent bias of the elastic component 14 equals a force required to support the foot and the drop angle D is an equilibrium angle of from 90 degrees to 100 degrees.
[0068] The cuff 12 serves as an anchor for the elastic component 14. The tensile force necessary to support the foot 200 in an orientation where the sole of the foot 200 is approximately perpendicular to the axis of the tibia 300 is transmitted through the elastic component 14. The entire tensile load is diffused through the cuff 12 and distributed around the ankle 50, including the lateral and medial sides.
[00691 The elasticity of the elastic component 14 helps the user to create a natural gait when walking. When the user raises his or her foot 200 above the ground to take a step, the elastic component 14 keeps the drop angle D at the equilibrium angle in the range of 90 degrees to 100 degrees which effectively positions the foot 200 for a natural and comfortable heel to toe step, followed by a natural and comfortable lifting of the foot 200 after each step.
[0070] The attachment of the elastic component 14 to the cuff 12 at the front of the user's ankle 50 provides a simple, stronger and more effective anchor for the elastic component 14.
By attaching to the cuff 12 at the front of the ankle 50, the elastic component 14 does not need to extend around to the side or back of the user's ankle 50. By attaching to the cuff 12 at the front of the ankle 50, the elastic component 14 can raise the toes directly towards the front of the ankle 50, instead of towards the side of the ankle 50, thus allowing for a more natural and comfortable heel to toe step.
[0071] The attachment of the elastic component 14 to the vamp 62 at a location proximal to or at the user's toes is preferred. This allows the elastic component 14 to raise the foot 200 close to or at the location which experiences the largest drop when the user cannot raise his or her foot 200 at the ankle joint.

100721 The ankle foot orthosis of the present invention is more comfortable and lighter in weight than previous devices, such as splints. Unlike the previous splints, the ankle foot orthosis of the present invention is not prone to breakage. The ankle foot orthosis of the present invention is easily washed. It is relatively small in size and discrete for the user to wear, especially if hidden under pant legs. The ankle foot orthosis can be transferred from one footwear garment to another because it is easily attachable and detachable. Many conventional shoes, boots, slippers and sandals can be used with the ankle foot orthosis of the present invention.
[00731 Although this disclosure has described and illustrated preferred embodiments of the invention, it is to be understood that the invention is not restricted to these particular embodiments. Rather, the invention includes all embodiments that are functional or mechanical equivalents of the specific embodiments in features that have been described and illustrated herein. Many modifications will now occur to those skilled in the art. For a definition of the invention, reference is made to the following claims.

Claims

1. An ankle foot orthosis comprising:
a cuff for securement around a user's ankle, and an elastic component comprising a first end and a second end;
wherein the elastic component has an inherent bias to assume a condition in which a distance between the first end and the second end is an unextended length;
wherein when tension is applied to the elastic component against the inherent bias, the distance between the first end and the second end increases to an extended length, and the inherent bias attempts to return the elastic component to the unextended length;
wherein the first end of the elastic component is fastened to the cuff at the front of the user's ankle;
wherein the second end of the elastic component is fastened to a vamp of a footwear garment being worn on the user's foot at a location above the user's foot and closer to the user's toes than to the user's ankle.

2. The ankle foot orthosis of claim 1, wherein the cuff is engaged around the ankle to resist sliding downwardly relative to the ankle.

3. The ankle foot orthosis of claim 1, wherein the angle between the sole of the user's foot and an axis of the user's tibia is a drop angle, wherein the elastic component is in a condition without tension when the drop angle is less than 90 degrees, and wherein the elastic component is first placed in a condition under a tension when the drop angle is an initial tension angle greater than 90 degrees.

4. The ankle foot orthosis of claim 3, wherein when the user lifts his or her foot above the ground with the user's tibia generally vertical and the user's foot is relaxed, an equilibrium condition occurs in which the inherent bias of the elastic component equals a force required to support the foot and the drop angle is an equilibrium angle in the range of 90 degrees to 100 degrees.

5. The ankle foot orthosis of claim 4, wherein the inherent bias prevents the drop angle from exceeding a maximum angle of 135 degrees.

6. The ankle foot orthosis of claim 3, wherein the initial tension angle is about 90 degrees.

7. The ankle foot orthosis of claim 4, wherein the equilibrium angle is in the range of 90 degrees to 100 degrees.

8. The ankle foot orthosis of claim 4, wherein the equilibrium angle is about degrees.

9. The ankle foot orthosis of claim 1, wherein the cuff is a panel which wraps around the user's ankle, said panel comprising a first end and a second end, wherein the first end of the panel is secured to the second end of the panel to form a closed loop when the cuff is wrapped around the user's ankle.

10. The ankle foot orthosis of claim 1, wherein the cuff comprises an outer layer and an inner layer, wherein the outer layer comprises an elastomer or a textile, and wherein the inner layer comprises material selected from the group consisting of foam, felt and neoprene.

11. The ankle foot orthosis of claim 1, wherein the elastic component is an elastic band.

12 12. The ankle foot orthosis of claim 1, wherein the elastic component is an elastic cord.

13. The ankle foot orthosis of claim 1, wherein the elastic component is a shock cord.

14. The ankle foot orthosis of claim 1, wherein the first end of the elastic component is permanently sewn to the cuff.

15. The ankle foot orthosis of claim 14, wherein the shock cord is attached between the outer surface and the inner surface of the cuff at the front of the user's ankle.

16. The ankle foot orthosis of claim 1, wherein the second end of the elastic component is fastened to the vamp at a location proximal to or at the user's toes.

17. The ankle foot orthosis of claim 1, wherein the second end of the elastic component is fastened to the vamp by a snap hook.

18. The ankle foot orthosis of claim 17, wherein the snap hook attaches to laces of the footwear garment.

19. The ankle foot orthosis of claim 17, wherein the snap hook attaches to a closed ring or loop or a closed band, wherein the closed ring or loop or the closed band are part of the footwear garment.

20. The ankle foot orthosis of claim 1, wherein the footwear garment is selected from the group consisting of a shoe, a boot, a sandal, a slipper and a sock.