Abstract:
A knee orthosis comprising of at least one deflection limiter ( 66 ) separated by gaps ( 10 ) on one or more struts ( 67 ), which are attached to a thigh shell ( 18 ) and a calf shell ( 68 ). The stiffness of the brace can easily be controlled in sagittal, transverse, and coronal planes whereby a person may obtain improved gait.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/663556 filed Mar. 18, 2005. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH  
       [0002]     The U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by the terms of Grant No. H133E003001 awarded by the U.S. Department of Education. 
     
    
     SEQUENCE LISTING OR PROGRAM  
       [0003]     Not applicable  
       BACKGROUND—FIELD OF THE INVENTION  
       [0004]     The present invention relates to improvements in a knee orthosis (KO) used for supporting a person&#39;s knee along with extensions for supporting the user&#39;s hip and ankle. The orthosis of the present invention assists the user in extension and flexion of the user&#39;s hip, knee, and ankle while controlling sagittal, transverse, and/or coronal plane stiffnesses and deflections.  
       BACKGROUND—DISCUSSION OF PRIOR ART  
       [0005]     Knee Orthoses are currently used to support the knee when there is muscle weakness, bone deformity, joint deformity, joint damage, tendon damage, ligament damage, and/or whenever the loads and moments applied are higher than the person&#39;s physiology can handle.  
         [0006]     Knee orthoses are commonly used in combination with ankle-foot orthoses to make knee-ankle foot orthoses (KAFO&#39;s), and hip orthoses to make Hip-knee-ankle-foot orthoses (HKAFO&#39;s).  
         [0007]     The disadvantages of current KO&#39;s are that they cannot apply a moment across the knee that is biomechanically suitable. The human body uses its muscles to apply a non-linear moment across the knee for a full range of motion of the knee.  
         [0008]     Current knee joints lock the knee entirely, lock the knee for all of stance phase of the gait cycle, or allow it to flex during stance phase, but not during swing phase. The normal human has high stiffness knee flexion during the load response part of stance phase, and low stiffness knee flexion during swing phase. No current knee orthoses provide these stiffness and range of motion properties.  
         [0009]     The stiffness of an individual&#39; knee varies with their weight, height, activity level, loads carried, strength and other factors. This brace allows an orthosis with a particular stiffness to be fabricated for a particular individual or class of individuals.  
         [0010]     Current braces have very rigid flexion stops and/or extension stops, which cause sudden decelerations. These decelerations over time can damage a patient&#39;s knee and hip joints. Slower decelerations such as those applied by a normal person&#39;s muscles may be better.  
         [0011]     U.S. patent application Ser. No. 11/111,973 by Reynolds et al shows a technology for controlling the ankle joint using segments on at least one strut.  
         [0012]     There is a need for a knee orthosis, which applies a controlled non-linear stiffness across the knee in both flexion and extension that is similar to the stiffness applied by a normal person&#39;s muscles during gait. This stiffness needs to be reduced for sitting and swing phase.  
       SUMMARY  
       [0013]     The knee orthosis described in this application provides significantly enhanced performance compared to currently available knee orthoses. This orthoses has at least one strut, a thigh shell, a calf shell and at least one deflection limiter with gaps between the deflection limiter and the calf and thigh shell. 
     
    
     DRAWINGS  
       [0014]      FIG. 1  is a perspective right-side view of a right leg knee orthosis constructed in accordance with the invention. The knee orthosis used for the left leg is a mirror image.  
         [0015]      FIG. 2  is a lateral side view of  FIG. 1 . It shows a thigh shell, defection limiters, and the spacers between the deflection limiters.  
         [0016]      FIG. 3  is a view in detail of the portion indicated by the section line  3 - 3  in  FIG. 2 . It shows the spacers between the deflection limiters, and the holes for a knee extension assist device, and a locking/unlocking linkage.  
         [0017]      FIG. 4  is a posterior perspective view of the knee orthosis with optional hip extension, optional Posterior Strut Ankle Foot Orthosis extension and optional Medial Lateral Strut Ankle Foot Orthosis extension. The orthoses used for the left leg are mirror images. 
     
    
     NUMERALS IN DRAWINGS  
       [0000]    
       
         
           
               7  Comfort Liner  
               10  Knee orthosis tab for attachment to ankle foot orthosis  
               11  Hole for Pin#  52   
               12  Knee hinge  
               13  Lock/Unlock Rod  
               14  Spacers  
               15  Extension assist  
               16  Thigh straps with hook and loop closure  
               17  Lock/unlock drive rod  
               18  Thigh shell  
               20  Hook and loop closure  
               22  Hook and loop closure  
               24  Hip joint  
               26  Pin to retain tab  62   
               27  Strut with slot for attachment to knee orthosis  
               28  Slot for attachment to Tab ( 10 ) on knee orthosis  
               30  Lock/unlock drive rod  
               32  Lock/unlock drive tube  
               34  Medial lateral strut AFO calf shell  
               36  AFO lateral support strut  
               38  Lock/unlock drive rod length adjustment  
               40  Lock/unlock drive rod length adjustment  
               42  Drive rod attachment to foot shell  
               44  Lateral ankle joint  
               46  Foot shell  
               48  Lock/unlock drive rod  
               50  Posterior strut AFO calf shell  
               52  Pin to hold knee orthosis tab in place  
               54  Rocker to change direction of drive rod  
               56  Lock/unlock drive rod connector  
               62  Tab for attachment to hip extension  
               63  Hole for Pin # 26   
               64  Hook and loop closure  
               66  Deflection limiters  
               67  Strut  
               68  Calf shell  
               70  Hip band  
           
         
       
     
       DESCRIPTION OF THE INVENTION  
       [0055]     The present invention relates to a knee orthosis (“orthosis”) worn by a user on the user&#39;s leg or optionally on the user&#39;s hip and leg. The orthosis supports and assists users who have difficulty in standing and walking. Additionally, a user having no such difficulty can use the orthosis to assist their normal movement, which may assist the user&#39;s performance and endurance.  
         [0056]      FIG. 1  shows a knee orthosis constructed and arranged in accordance with the invention. It consists of a thigh shell  18 , which is securely attached to the wearer&#39;s thigh. It could be a generic shape or it may be custom made for a particular individual&#39;s leg. It could have anterior segments and/or posterior segments connecting the medial and lateral sides, and/or it could be spiral shaped and wrap around the thigh, and/or it could have straps with hook and loop closures and/or buckles or other attachments across the anterior sides  16 ,  4 , and/or posterior straps, and/or encircling straps, and or no straps.  
         [0057]     Attached to the thigh shell on the medial and lateral sides are struts  67 (seen in the cross-section  FIG. 3 ) which could consist of one piece or multiple struts. A single strut on only the medial or lateral side is also possible. The preferred embodiment has two struts on the medial and lateral side of the leg.  
         [0058]     The orientation of the struts  67  from the thigh shell  18  to the knee joints  12  can be set at an angle to the line between the center of the wearer&#39;s anatomical hip joint to the center of the wearer&#39;s anatomical knee joint. This in combination with the below knee struts  67 , and locked knee joints  12  allows the knee angle that the brace applies zero moment to the leg to be controlled. For example, if the knee joints  12  lock at 180 degrees and the above knee struts are oriented in 10 degrees of flexion to the hip to knee line, and the below knee struts  67  are oriented in 0 degrees of flexion to the knee to ankle line then the orthosis will apply zero moment at 10 degrees of knee flexion. This angle can be customized to the needs of the user.  
         [0059]     Below the thigh shell, a one or more rigid segments called deflection limiters  66  surround the struts  67  or are attached to the struts  67 . The deflection limiters  66  can be tapered, expanded, or parallel on the proximal and/or distal edges of the posterior and/or anterior sides to allow a different deflection or stiffness in flexion than in extension (tapering on the posterior side shown). Between the thigh shell  18  and the deflection limiters  66 , and between the deflection limiters  66  themselves are rigid spacers  14  which allow the struts  67  to bend in a very controlled manner. The height of the spacers  14  and the shape of the deflection limiters  66  controls when the deflection limiters touch each other and the calf shells  68  and thigh shells  18  as the struts bend. These spacers could be separate pieces or incorporated into the shape of the deflection limiters  66 . As strut  67  bends, the gaps controlled by the spacers  14  and the shape of the deflection limiters  66  progressively close. When the deflection limiters  66  touch each other or the thigh shell  18  or the calf shell  68 , they effectively shorten the unsupported length of strut  67 , increasing the stiffness of the knee orthosis.  
         [0060]     Attached to the strut  67 , below the deflection limiters  66 , are the knee joints  12 . This can be any type of knee joint such as a locking joint, a ratcheting lock joint, a stance-locking joint, range of motion-limited joint, and/or a free joint. The medial and lateral knee joints  12  may be of different types. In an additional configuration, both knee joints  12  can be removed allowing the strut to continue through this area and adding deflection limiters and spacers (if needed). In a further configuration, if only minimal support is needed, the medial knee joint  12 , deflection limiters  66  and strut  67  may be removed entirely.  
         [0061]     Below the knee joint  12  is another section of medial-lateral struts  67  with spacers  14  and deflection limiters  66  constructed in the same manner as above. The number of deflection limiters  66  and spacers  14  may vary as needed.  
         [0062]     Towards its distal end, the strut  67  is attached to a calf shell  68 . The calf shell  68  may be a generic shape or it may be custom made for a particular individual&#39;s leg. It could have anterior and/or posterior bars (not shown) connecting the medial and lateral sides, and/or it could be spiral shaped and wrap around the calf (not shown), and/or it could have straps with hook and loop closures  16 ,  4  and/or buckles-across the anterior side, and/or posterior straps, and/or encircling straps, and/or it can be constructed so that when it mates with an AFO, the AFO helps hold it on the lower leg (shown in  FIG. 1 ,  FIG. 2 ,  FIG. 3 , and  FIG. 4 ).  
         [0063]     The orientation of the struts  67  from the calf shell  68  to the knee joint  12  can be set at an angle to the line between the center of the wearer&#39;s anatomical knee joint and the center of the anatomical ankle joint. This in combination with the strut  67  above the knee joints  12  allows the knee angle that the brace applies zero moment across the knee to be controlled. For example, if the knee joints  12  lock at 180 degrees and the above knee struts  67  are oriented in 0 degrees of flexion to the hip to knee line, and the below knee struts  67  are oriented in 10 degrees of flexion to the knee to ankle line, then the orthosis will apply zero moment at 10 degrees of knee flexion. This angle can be customized to the needs of the user.  
         [0064]     The gaps between the deflection limiters  66  themselves and between the calf shells  68  and thigh shells  18  and the deflection limiters  66  can be controlled by a variety of means such as through an integral step in the deflection limiters and the shells, through tapering or expanding the deflection limiters  66  or calf shells  68  and thigh shells  18  (shown in  FIG. 2 ), and/or through the addition of rigid spacers  14  (as in  FIG. 1 ,  FIG. 2 ,  FIG. 3 ., and  FIG. 4 ), and by attaching the deflection limiters  66  directly to the strut  67 .  
         [0065]      FIG. 2  shows the lateral side view of the knee orthosis shown in  FIG. 1  for use on the right leg. There is a comfort liner  63  on the inside of the thigh shell  18  and calf shell  68  to provide padding next to the wearer.  
         [0066]      FIG. 3  shows the cross-section of the knee orthosis at section line  3 - 3 . Visible are the struts  67  which each could consist of a single strut or multiple smaller struts, spacers  14 , lock unlock rods  16  which could be round or square, and the holes  15  through which the extension assist mechanism passes. A cross-section through the struts  67  above the knee joints  12  would be similar.  
         [0067]     Along the anterior side of each strut is an optional knee extension assist mechanism located in holes  15 . This consists of a bungee cord, spring, flexible rod or combination of similar devices that is attached to the deflection limiters or the thigh and calf shells and crosses the knee joint on its anterior side. When the joint is unlocked and the knee bends the device resists flexion.  
         [0068]     Along the posterior side of each strut is a lock/unlock rod  17  in a hole or channel. This can be used when a locking knee joint or stance control knee joint is used. This rod allows the knee brace to be unlocked during swing and locked during stance by the angle of the ankle (shown in  FIG. 4 ) or by contact with the ground, or a foot switch, or a solenoid or other mechanism (not shown). If the direction of the lock/unlock rod  48 ,  17 ,  13  needs to be changed, a simple mechanism  54  such as a pivot can be used. The lock/unlock rod  13  can cross into the AFO adjacent to tab  10 . It engages automatically when the AFO is attached. It may also be unlocked by full knee extension.  
         [0069]     In an alternate configuration, some stance locking knee joints such as the Stance Phase Lock by Basko Healthcare do not require this lock/unlock rod  17 . In an alternate configuration, a knee joint can be locked and unlocked by a lever or other mechanism that is triggered by knee flexion and weight bearing  
         [0070]     In another embodiment, the length of the lock/unlock rod  48 , 13 , 17  and when it triggers can also be easily adjusted by a mechanism  38 ,  40  which consists of a bar attached to the footshell of the AFO by connector  42  which slides on the drive rod when the ankle is rotated. This bar which will only move the lock/unlock rod  13  when it contacts blocks attached to the drive rod. Other similar mechanisms such as those found on bicycle brakes will also work.  
         [0071]     A stance locking knee joint can also be fabricated in this orthosis by using a freely rotating knee joint and a lock/unlock rod  17  made of a durable material such as metal. During plantarflexion of the ankle or some other locking signal, the rod pushes up and inserts into a slot or hole on the other side of the knee joint. This prevents rotation of the knee. If this hole is in a lock/unlock rod  17  that extends into the thigh shell, the knee joint  12  can be manually locked or unlocked by the wearer by lowering this lock/unlock rod  17  across the joint.  
         [0072]     A separate or connected lock/unlock rod  17  can also extend from the knee joint into the thigh shell allowing the knee to be manually locked, unlocked, or placed into automatic stance control mode by the wearer or an assistant.  
         [0073]      FIG. 4  is a posterior perspective view of the knee orthosis with optional hip extension, optional Posterior Strut Ankle Foot Orthosis extension and optional Medial Lateral Strut Ankle Foot Orthosis extension.  
         [0074]      FIG. 4  also shows the optional pins bolts, rivets, ball snaps, pip pins or other connector  52 , which attach the tabs  10 ,  62  to the AFO and hip orthosis. The shape of the knee orthosis calf shell  68  can be made with a step on the distal surface with a matching step on the proximal ankle foot orthosis calf shell  50  to facilitate connection and enhance support between the AFO and the knee orthosis.  
         [0075]     At the bottom of the calf shell  88  are optional tabs  10  that allow the knee orthosis to be attached to an optional medial-laterally jointed AFO or posteriorly jointed AFO.  
         [0076]     At the top of the thigh shell  18  is an optional tab  62  that allows the knee orthosis to attach to an optional hip orthosis.  
         [0077]     The parts of a typical medial/laterally jointed AFO are the footshell  46 , the ankle joint  44  which could be a free joint, a dorsiflexion assist joint, a dorsiflexion stop joint, a plantarflexion stop joint or a locked joint. Medial lateral struts  36  take the loads in the AFO. It has slots  28  for accepting tab  10 . It has a lock/unlock actuator rod  30  in a tube  32  and an ankle foot orthosis calf shell  34 .  
         [0078]     The parts of a posterior strut AFO are a foot shell  46 , an AFO calf shell  50 , and a drive rod  48 , 13  attached to the footshell with a connector  56 .  
         [0079]     The parts of a typical hip orthosis are a hip band  70  a strap  20  with a buckle, connector or hook and loop closure  22 . A hip joint  24  and a strut  27  with a slot to accept tab  62 .  
         [0080]     The same techniques used for adjusting flexion/extension stiffness described previously in this specification, such as adjusting the size of the spacers  14 , the size or number of struts  67 , or the shape of the deflection limiters  66 , can be used to control medial and lateral knee stiffness and deflection in the transverse plane, as well as torsion in the coronal plane. This can be useful for compensating for knee and ankle varus/valgus.  
         [0081]     The knee orthosis can be fabricated using various materials such as a fibrous material such as carbon fiber or fiberglass impregnated or pultruded with thermoset resin such as acrylic or epoxy, or out of metals such as aluminum or stainless steel. Additionally, it can be made using thermoplastic materials such as polyethylene and polypropylene.  
       Preferred Embodiment  
       [0082]     The preferred embodiment will depend on a particular patients needs. This knee orthosis provides a convenient selection of devices and characteristics to allow it to be tailored to allow a wide variety of patients the ability walk with an improved gait.  
         [0083]     Many patients with severe calf and thigh weakness would use a configuration comprising of a posterior strut AFO connected to the knee orthosis. The knee orthosis strut  67  would be oriented 5 degrees forward of the line between the wearer&#39;s anatomical knee joint and hip joint, and 5 degrees forward of the line between the anatomical knee and ankle joints. This would make the knee moment equal to zero at a knee flexion angle of 10 degrees. There would be a knee extension assist consisting of elastic material. The knee joints  12  would be locking/unlocking knee joints with a lock/unlock rod  48 , 13  attached to the foot shell  46  of a posterior strut AFO connected through a pivot  54 . The orthosis knee joint would be located near or slightly posterior to the anatomical knee joint.  
       OPERATION OF THE INVENTION  
       [0084]     The knee orthosis is attached to or around the lower leg of the wearer. First, the AFO is attached to the foot using straps if necessary. The shoe is then placed over the footshell  46 . It is also possible to design the footshell  46  to fit over the shoe or not require a shoe at all.  
         [0085]     The knee joints  12  are manually unlocked by moving the lock/unlock rod  17  inside the thigh shell  18  and the thigh shell  18  is placed around the wearers thigh and tab  10  is placed in slot  28 . Straps  16  are then secured. If used, the hip orthosis is placed around the waist and tab  62  is attached to strut  27 . Strap  20  is then secured. The wearer then extends their legs, manually locks the knee joints  12 , stands up and walks. Sometimes additional assistive aids such as canes or walkers are also needed for ambulation. To remove the orthosis, the process is reversed.  
         [0086]     In operation, almost any kind of knee stiffness curve can be predictably obtained using this invention. The size of the struts  67  determines the initial stiffness. The size of the spacers  14  and the shape of the deflection limiters  66  and calf shell  68  and thigh shells  18  determine how fast the stiffness increases. As the struts  67  bend, the gaps between the deflection limiters  66  progressively close and eventually touch each other or the calf shells  68  and thigh shells  18 . This prevents further bending and the effective length of the struts  67  are shortened, increasing their stiffness. The width of the gaps is measured from the struts&#39;  67  neutral axis and the gap height in an anterior/posterior manner determines how fast the stiffness increases. The smaller the gaps on the anterior side of the strut, the faster the stiffness in knee extension increases. The smaller the gaps on the posterior side, the faster the knee flexion stiffness increases.  
         [0087]     The stiffer the extension assist material  15 , the higher the extension assist force when the joint is unlocked.  
         [0088]     The desired initial stiffness of the knee orthosis can be determined by dividing the normal knee moment by the normal knee angle at every point in the gait cycle. This desired value can be modified depending on the wearer&#39;s strength, and needs of the wearer. Standard beam bending equations applied to the struts  67  can be used to predict the initial stiffness of the knee orthosis in the sagittal plane. As each gap closes, the new stiffness can be calculated with the same equations by progressively shortening the effective length of the struts  67  by the height of deflection limiters  66  with their gaps closed. The maximum deflection can be calculated through basic geometrical formulas.  
         [0089]     During gait, when the ankle plantarflexes under body weight, the knee is unstable and needs to be supported. When the ankle dorsiflexes, the ground reaction forces extend the knee joint so it does not need to be prevented from flexion. So a linkage across the ankle can be used to lock and unlock a knee joint  12 .  
         [0090]     In another embodiment, during gait, a ground reaction force corresponding to the weight of the wearer applied posterior to the ankle joint creates a flexion moment on the knee. So when a pushrod near the heel is compressed by body weight, it can trigger a lock at the knee. When the heel lifts up such as during push off, the spring-loaded pushrod returns to its original position and the knee is unlocked for swing through.  
         [0091]     During the load response part of the gait cycle, a normal human flexes their knee. This brace allows the knee to be supportably flexed with a controlled stiffness during load response when the knee joint  12  is locked.  
         [0092]     To sit down the wearer puts their knee into a neutral angle, pulls on the lock/unlock rod  17  in the thigh shell  18  to unlock the knee joint  12 . Then the wearer sits down. The orthosis allows the knee to flex past 90 degrees. To stand up, the process is reversed.  
       Description and Operation of Alternative Embodiments  
       [0093]     An alternate configuration, to allow a variable stiffness curve, for a patient with a changing clinical picture, for changing terrain conditions, for more accurate initial stiffness setting, or many other reasons, consists of replacing some or all of the rigid spacers  14  with elastic spacers  14  made out of a material such as rubber and adding a device to compress the elastic spacers  14  such as a cam located medially or laterally to the strut (not shown) or a mechanism as simple as two locknuts on a threaded rod inserted into holes (not shown) fabricated in the deflection limiters  66  and the thigh shell  18  and calf shell  68 . The holes would be located equidistant on the anterior and posterior sides of the strut. When the locknuts are turned in opposite directions on the threaded rod (or the cam rotated), the deflection limiters  66  and therefore the elastic spacers  14  are placed under compression, reducing the gaps between the deflection limiters  66  and between the thigh shells  18  and calf shells  68  thereby stiffening the knee orthosis. This configuration allows quick and simple brace stiffness modification.  
         [0094]     Another alternative embodiment of this knee orthosis is where the deflection limiters  66  are two separate rectangular blocks attached solely to the anterior and posterior sides of the struts rather than a single piece that surrounds the strut as shown in  FIG. 1 . These rectangular blocks would work in the same as the previously described deflection limiters  66 . The calf shell  50  and foot shell  52  would be similar to those previous described.  
       CONCLUSION, RAMIFICATIONS, AND SCOPE OF INVENTION  
       [0095]     Thus the reader will see that the knee orthosis which allows controlled non-linear knee stiffness in both flexion and extension comprising of deflection limiters  66  attached and/or surrounding a strut  67  which is attached to a thigh shell  18  and a calf shell  68 , provides significant improvements in the ability to fit a particular patient&#39;s knee stiffness needs.  
         [0096]     While principles of the invention are amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure and claims.