Abstract:
An ankle-foot orthotic is provide for assisting persons having lower extremity weakness including weak dorsiflexor and plantar flexor muscle groups. A combination of flexible and stiff polypropylene and polyethylene materials are used to assist in the transfer of energy along the components of the ankle-foot orthotic to mimic normal gait.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to devices for supporting the ankle and foot for persons who experience lower extremity weakness. More particularly, the invention relates to a novel laminate structured ankle-foot orthotic for preventing the foot from limited or uncontrolled rotation at the ankle resulting in the dropping of the foot, dragging of the toe upon, or slapping of the foot while walking 
       BACKGROUND OF THE INVENTION 
       [0002]    Lower extremity weakness is a concern for many persons and often affects the gait of the person. An example of the manifestation of lower extremity weakness is a condition called foot drop where the foot falls forward while walking due to weak or decreased (or lost) motor control of the dorsiflexors muscles. The plantar flexors muscles assist in control the movement of the foot after planting of the heel towards the end of the stride called heal strike. If the plantar flexor muscle group is weak or injured the toes and forward portion of the foot may uncontrollably slaps the ground upon heal strike. Various medical conditions can manifest in the weakening of the dorsiflexor and plantar flexor muscles such as nerve damage from injury, diabetes or motor neuron diseases such as amyotrophic lateral sclerosis (“ALS”), multiple sclerosis, post-polio syndrome, and brain, spinal cord or back injuries. 
         [0003]    To compensate for foot drop, the person may exaggerate the swinging motion at the hip of the affected leg, leading with the knee to prevent the toes from dragging or catching on the ground. Some instances of foot drop can be corrected by surgery. However, in those cases in which surgery is ineffective, orthotic devices are typically used to maintain the forward portion of the foot forward or prevent or limit downward motion of the toes as the foot is carried forward during a stride. These orthotic devices, typically called an ankle-foot orthotics, often limit the range of downward motion of the foot at the ankle or completely prevent the downward motion. In use, these orthotics devices often result in an awkward gait. Often these ankle-foot orthotics utilize a stiff plate that the foot rests upon and a support member that travels from the heal of the orthotic to the back of the calf of the leg with a calf strap to hold the orthotic to the leg. The foot plate of these stiff orthotics are often difficult to place in the user&#39;s shoes and are uncomfortable. 
         [0004]    Another method of preventing the toe portion of the foot from uncontrollably rotating at the ankle is with the use of a top position ankle-foot orthotic that supports the affected foot from the top of the foot and shin. A stiff “L” shaped support member is attached on the top of the foot and above the ankle on the shin. These front-support ankle-foot orthotic devices are often more comfortable than the anterior positioned orthotic, but are difficult to walk in and are best used during less active times when the user does less walking. An more active type front support method uses straps attached at the ball of the foot portion of the user&#39;s shoe with stiff straps that cross around the ankle to prevent the toe from dropping downward. Similar designs may use less noticeable, small straps such as cording with an ankle high shoe device such as a high-top athletic shoe. Most of these top of the foot support devices result in a stiff gait because the orthotic limits the rotation at the ankle. 
         [0005]    It is desirable to have an ankle-foot orthotic that allows some controlled downward rotation of the foot about the ankle and provide rebound of the foot to allow the user to mimic normal gait without the user exaggerating the throw of the leg from the hip. Likewise, it is desirable to provide an orthotic that is easy to wear and comfortable to increase the use of the orthotic. 
       SUMMARY OF THE INVENTION 
       [0006]    An improved, back support ankle-foot orthotic is provided in various embodiments that allow for downward plantar flexion, upward dorsiflexion, and utilizes the kinetic energy of the orthotic as it compresses and extends during walking motions. It is advantageous to provide an ankle-foot orthotic that utilizes a flexible, light-weight material that provides some flexing of the leg support and a flexible foot plate capable of transferring energy along the components of the ankle-foot orthotic. 
         [0007]    The foregoing and other objects are intended to be illustrative of the invention and are not meant in a limiting sense. Many possible embodiments of the invention may be made and will be readily evident upon a study of the following specification and accompanying drawings comprising a part thereof. Various features and subcombinations of the invention may be employed without reference to other features and subcombinations. Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example, an embodiment of this invention. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0008]    Preferred embodiments of the invention, illustrative of the best modes in which the applicant has contemplated applying the principles, are set forth in the following description and are shown in the drawings and are particularly and distinctly pointed out and set forth in the appended claims. 
           [0009]      FIG. 1  shows a right side elevation view of an embodiment having a vertical, reinforced strut support member, calf cuff and attachment strap, reinforced heal cup and foot plate; 
           [0010]      FIG. 2  is front elevation view of an embodiment illustrating a vertical reinforced strut, calf cuff and attachment strap, heal cup and foot plate; 
           [0011]      FIG. 3  is a top plan view of an embodiment illustrating internal location of reinforced strut, foot plate, heel cup and calf cuff and attachment strap; 
           [0012]      FIG. 4  is a cross-sectional view at plan created by line  4 - 4  in  FIG. 2  showing the internal reinforcement of the strut. 
           [0013]      FIG. 5  is a right side elevation view of an embodiment fitted on a leg at the heal strike position during walking and illustration of resulting ground reactive force; 
           [0014]      FIG. 6  is a continued right side elevation view of an embodiment fitted on a leg after heal strike and into midstance; 
           [0015]      FIG. 7  is a continued right side elevation view of an embodiment fitted on a leg at midstance into heel off; and 
           [0016]      FIG. 8  shows a continued right side elevation view of an embodiment fitted on a leg at heel off into toe off; 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0017]    As required, detailed embodiments of the present inventions are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. 
         [0018]    Referring to  FIGS. 1 and 2 , an embodiment of the invention, ankle-foot orthotic  10  is shown comprising a vertical strut  12 , calf cuff  14  and an attachment strap  16  with hook and loop fastening material to secure ankle-foot orthotic  10  to the leg of the user. Ankle-foot orthotic  10  has a heal cup  18  which transitions into a foot plate  20 . An embodiment of ankle-foot orthotic  10  is constructed from plastic materials that provide rigidity to support the foot and ankle and, at the same time, may be compressed and rebound to the uncompressed condition. Kinetic energy is converted into potential energy when material is compressed and when the material is released from its compressed state, the potential energy is converted to kinetic energy and acts upon the supported structure—the foot and lower leg. 
         [0019]    One embodiment of ankle-foot orthotic  10  is composed of a combination of polyethylene which provides flexibility and polypropylene which contributes stiffness. The actual ratios of the materials may be adjusted to obtain the adequate stiffness and flexibility of the ankle-foot orthotic  10  for a specific embodiment. Moreover, various thicknesses of polyethylene and polypropylene may be to create desirable physical properties. Likewise, hybrid materials and copolymers comprised of both polyethylene and polypropylene may be used. 
         [0020]    The build up of materials of one embodiment is shown in  FIG. 4  and is illustrates the cross-section of vertical strut  12  along line  4 - 4  of  FIG. 2 . In this embodiment, the posterior outer layer  22  of vertical strut  12  is constructed of polypropylene which provides stiffness to the structure. Moreover, the curvature of posterior outer layer  22  also contributes to the stiffness of vertical strut  12 . To provide flexibility and allow compression of vertical strut  12 , an interior strut bead  24  is located down the interior center of vertical strut  12 . Polyethylene is used to provide flexibility of vertical strut  12  and allow for the compression of vertical strut  12  to store and transfer energy in compression and tension. Likewise, an anterior layer  26  of vertical strut  12  may also be composed of polyethylene to increase the flexibility of vertical strut  12 . However, if greater strength is need, anterior layer  26  may be composed of either polypropylene or a hybrid material of polypropylene/polyethylene. The left  28  and rights  30  edges or side margins of vertical strut  12  may be construed of polypropylene to provide rigidity of the edges of vertical strut  12 . 
         [0021]    Returning to  FIGS. 1 through 3 , the stiffer polypropylene posterior layer  22  of vertical strut  12  portions of the provide pathways for transferring kinetic energy of the ankle-foot orthotic  10 . An energy pathway  32  along vertical strut  12  is shown in  FIGS. 1 and 2  as the area between the dashed lines. Energy pathway  32  travels along the vertical strut  12  and branches outwardly at heal cup  18  at left  28  and right  30  side margins and terminates in foot plate  20 . The termination of energy pathway  32  in foot plate  20  is also shown in  FIG. 3 . The termination line provides for flexing of foot plate  20  as when the foot plate is flexed during the conditions of walking. Also note that flexible interior strut bead  24  communicates with energy pathway  32  along vertical strut  12  and terminates at the split of energy pathway  32  along left  28  and right  30  margins of heal cup  18 . (See  FIG. 2 .) 
         [0022]    Turning to  FIGS. 5-8 , the ankle-foot orthotic  10  is illustrated undergoing the walking process and acting ground reaction forces.  FIG. 5  shows the ankle-foot at the “heel strike” position. In position, the brace supports the plantar flexes of the lower leg to allow for the foot to come to “foot flat” and the ground reaction forces acting upon the vertical strut  12  and calf cuff  14 , pushes the knee into flexion. Ankle-foot orthotic  10  helps limit “foot slap” by controlling the downward and forward motion of the foot. Once the foot is in the flat the position is referred to as “midstance”. At. midstance the lower leg is perpendicular to the floor and the ground reactive forces acting upon ankle-foot orthotic are negligible. From this midstance position, the leg and ankle-foot orthotic  10  progress forward and the orthotic and the dorsiflexors resist the forward motion which pushes the knee into extension as seen in  FIG. 6 . Also, this movement forces foot plate  20  to flatten and store energy as shown in  FIG. 7 . From this midstance position the forward movement causes the heel to lift, “heel off” to “toe off” shown in  FIG. 8 . In the heel off position, the foot flexes at the joints of the foot metatarsals and the phalanges of the toes. At this position, flexible foot plate  20  and vertical strut  12  rebound driving the toe of the foot and the knee upward to prevent “foot drop” and the dragging of the toes. 
         [0023]    In the foregoing description, certain terms have been used for brevity, clearness and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed. Moreover, the description and illustration of the inventions is by way of example, and the scope of the inventions is not limited to the exact details shown or described. 
         [0024]    Certain changes may be made in embodying the above invention, and in the construction thereof, without departing from the spirit and scope of the invention. It is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not meant in a limiting sense. 
         [0025]    Having now described the features, discoveries and principles of the invention, the manner in which the inventive neonate nutrition warming device and heat transfer for warming formula and nutritional media for babies are constructed and used, the characteristics of the construction, and advantageous, new and useful results obtained; the new and useful structures, devices, elements, arrangements, parts and combinations, are set forth in the appended claims. 
         [0026]    It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.