Abstract:
An assembly for an orthosis includes a flexure unit for joining two parts of the orthosis, such as a foot shell and an ankle or leg shell. One end portion of the flexure unit is supported on a housing that permits angular adjustment of the end portion of the flexure unit relative to the section of the orthosis on which the end portion is mounted. The angular adjustment is accomplished by utilizing a positive drive between a base portion and a housing that traps the end portion of the flexure in position on the base. This permits varying the assisting force, for example, toe lift, of the flexure unit between orthosis shell parts when the orthosis is worn.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to mountings for flexure units that are used as hinges, specifically on orthosis to provide adjustability of the angular position of the ends of the flexure units about mounting pins used for the ends. This adjustment provides a variable assist for toe lift on an ankle joint orthosis.  
           [0002]    Flexure units are used to provide joint motion, such as at an ankle joint, between a leg supported shell and a foot shell or stirrup. Flexure units or flexures are short columns or straps of polyurethane or other suitable thermoplastic materials. The column or strap lengths have sufficient thickness to provide a resilient bendable coupling connected between two components, for example, two parts of an orthosis shell. The flexure units function like a spring loaded hinge, and can be mounted in pairs on opposite sides of the ankle joint, for example. When used in pairs the flexure units form a joint system with a single axis of rotation passing through the flexure column midsections, that is, the elastomeric or polyurethane center portions of the flexure length. Flexures are secured, generally on pins, to the two hinged parts, such as components of a typical orthosis, including a lower leg shell and the foot support component which is called a foot shell. The elastomeric column will provide a biasing force to urge the toe of the person wearing the orthosis upwardly when no load is being exerted on the foot shell. The amount of toe lift force needed may be different for wearers, and can change from time to time.  
           [0003]    It has been found in the prior art that flexure units can be provided with a preset angular configuration that when secured to the mounting components on the orthosis shell, the parts that are hinged together will be at an angle and when worn will provide a bias force. In the case of an ankle joint the toe lift force can be increased by angling the central longitudinal axis of the flexure unit.  
           [0004]    In many cases it is desirable to have an adjustable amount of resilient force tending to lift the toe of a foot supported in a foot shell for meeting individual patient&#39;s needs.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention relates to end supports for flexure hinge units, which are generally mounted in pairs to form a resilient pivoting joint. Flexure units that are secured between two parts of an orthosis shell including a leg shell and a foot shell, form an ankle joint hinge. At least one end of each flexure unit is mounted on the two parts, respectively, through adjustable housings that permit a change in the “at rest” angular position of the flexure unit mounted end relative to a support on the shell. The adjustment of the angular position of the one flexure end results in the ability to adjust assisting or lifting force on a foot shell, when the orthosis is worn. For example, in an orthosis shell for a foot, the amount the outer end of the foot shell portion is angled upwardly relative to the lower leg shell can be adjusted. When the orthosis is installed, and the foot shell is moved to conform to the ankle position of the wearer, the flexure units will yield to permit conforming, but a biasing force tending to return the foot shell to its at rest position will be provided. The person wearing the shell will have a force providing toe lift. Such lift force can be adjusted with the present invention.  
           [0006]    The present invention mounting housings for the flexures include, as shown, a base that mounts onto one orthosis shell part. The base is held from rotating so it stays in position. The base has a support post that receives the end of the flexure unit or column, and adjustable housing fits over the end of the flexure unit. The housing has an opening that fits over and pivots on the post and thus pivots relative to the base and the pivotal position is adjustable. As shown, a pinion and pinion gear drive is provided between the base and the housing at one end of the flexure. The other end of the flexure can be mounted in a conventional rivet or pin support on the other shell part, or if desired it also can be mounted with an angle adjustment housing.  
           [0007]    The flexure unit or column used is unrestrained in its center portions between the orthosis shell parts.  
           [0008]    The flexure end mounting housing of the present invention thus provides an adjustable angular position of the mounting housing and the end of the flexure unit held therein, about the central axis of the post that mounts the flexure unit.  
           [0009]    In the specific form shown, the base mounts a pinion or screw, which engages rack or pinion teeth on the outer end surface of the mounting housing. By turning the pinion, a rack and pinion drive is provided to pivot the mounting housing relative to the base to its desired angular position. The change in angle varies or changes the assisting force for toe lift. The pinion and gear effect can be calibrated so the change in assisting force for each turn of the pinion may be determined.  
           [0010]    If desired, both of the mountings for the flexure unit may have this adjustable end supports that can be changed in angular orientation about the mounting axis of the flexure unit relative to its support.  
           [0011]    The unrestrained central portion of the flexure forms a hinge, and resiliently conforms to pivoting action to provide an ankle joint or other suitable joint where a controlled pivotal mounting is desired.  
           [0012]    In the case of an ankle-foot orthosis, the dorsiflexion/planterflexion of the patient&#39;s ankle can be differently loaded by adjusting the angular position of the mounting housings for the flexure ends relative to their base supports.  
           [0013]    Other types of angular adjustment drives between the mounting housings and the base or mounting components can be used. For example various threaded components that would act against portions of the flexure mounting housing to provide a positive change in angular position and hold the mounting housing in such changed angular position can be used. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is a side elevational view of an orthosis shell having an orthosis foot support shell and lower leg shell held together with a flexure unit hinge mounted in accordance with the present invention;  
         [0015]    [0015]FIG. 2 is a rear view of the orthosis shell of FIG. 1;  
         [0016]    [0016]FIG. 3 is a bottom view of the othosis shell of FIG. 1;  
         [0017]    [0017]FIG. 4 is a sectional view taken as in line  4 - 4  in FIG. 3;  
         [0018]    [0018]FIG. 5 is a fragmentation side elevational view of a flexure unit mounting housing and base according to a preferred embodiment of the present invention with the shell covering broken away;  
         [0019]    [0019]FIG. 6 is a sectional view taken on line  6 - 6  in FIG. 5;  
         [0020]    [0020]FIG. 7 is a perspective view showing an interior of the outer mounting housing of the present invention;  
         [0021]    [0021]FIG. 8 is a perspective view of a typical base portion showing a mounting post for a flexure unit; and  
         [0022]    [0022]FIG. 9 is a schematic side view of an alternate embodiment with angle adjustments at both ends of the flexure. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    An orthosis assembly  10  is used in connection with an ankle joint, and the assembly includes a leg support shell  12  that fits around rear portions of a lower leg of a wearer, and it can be strapped in place in a normal manner. A foot shell  14  is used for supporting the foot of a wearer and moves about an ankle joint of the wearer. Shell sections  12  and  14  are joined together with a flexure assembly  16  on each side of the shells, forming an ankle joint. The flexure assembly  16  has right and left forms, and the right hand assembly is shown in detail. The left side is a mirror image of the right side.  
         [0024]    The flexure assembly  16  made to provide a biasing force for positioning the foot shell  14  relative to the lower leg shell section  12 , and to provide a certain amount of bias in an upward direction so that there is a “toe lift” action or assist by the flexure assembly  16 . The flexure assembly, as can be seen, includes a flexure unit or column  20  which is made of a suitable elastomeric material, such as polyurethane material. The flexure unit can be made in the manner shown in U.S. Pat. No. 5,826,304. The flexure unit or column  20  has a center elastomeric column portion  22  that is in turn extends between end or fastening portions  24  (see FIG. 5). The lower end of the flexure unit or column  20  as shown is connected to the foot shell  14  with a non-adjustable connection  15  such as a rivet or screw, as is done in prior art.  
         [0025]    The upper end portion  24  is mounted as shown, in an angularly adjustable flexure unit mounting assembly  26 , that permits pivoting the end portions  24  about a central axis of a bore  29  in each end portion  24  that is used for mounting the flexures. The bores  29  may have bushings in the bores for strength. The bores  29  fit on posts  34  on the base plates  28 .  
         [0026]    Each of the adjustable mounting assemblies  26  includes a base plate  28  that is on the interior of an inwardly opening recess  27  formed by walls  27 A, B and C that protrude on the sides of shell section  12 . The base plates are held securely on shell section  12 .  
         [0027]    The base plates  28  have upper end lugs  33  that fit into a slot in the top wall  27 A forming part of recess  27  to prevent rotation of the base plate  28  relative to the shell post  12 . Other types of fasteners can be used to insure the base plate  28  will not move relative to the shell.  
         [0028]    The end portion  24  of each flexure unit or column  20  is retained on a post  34  on the base plate  28  within an overlying adjustable housing  30 . The housing  30  captures and supports the respective end portion  24  of a flexure unit. The housing  30  has a wall  31  (FIGS. 6 and 7) at a side thereof which is parallel to the base plate  28 , and adjacent wall  27 B forming a recess  27  on shell post  12 . (See FIG. 4) A bore  50  fits over the post  34  mounted on the respective base plate for pivotally mounting the housing  30 . A threaded screw  36  is threaded into a bore in the post  34  and has a head that bears on wall  27 B for retaining the cover member  30  in position on the respective post  34 . The base plate  28  and post  34  is integral with the base plate and the base plate is secured to wall  27 B forming part of recess  27  with the screw  36  as well. The head of the screw clamps the wall  27 B against the end of post  34 . The housing  30  traps the associated end portion  24  of the flexure unit  20  for pivotal movement about the post  34 . The screw  36  and lug  33  serve to mount the base  28  securely.  
         [0029]    An integral edge wall  38  curves around the end of the housing  30  as seen in FIG. 5, and wall  38  joins reaction walls  40  at the first and rear sides of the housing  30  that restrict movement of the flexure end  24  relative to the housing. Walls  38  and  40  are perpendicular to wall  31  and the end portion  24  is confined so the end of the flexure moves with the housing. The respective end portion  24  of the flexure unit held in the respective housing  30  will pivot on post  34  only by pivoting the housing  30 . The pivoting of the housing  30  about its mounting post  34  is controlled with an adjustment device  42  that in the form shown, comprises a threaded pinion or screw  44  supported in a pinion retainer frame  46  on the upper portion of the base plate  28 . The pinion is positioned to engage rack teeth or pinion gear teeth  48  on the upper periphery of wall  38  of housing  30 , when housing  30  is in place on pin  34 .  
         [0030]    As shown in FIGS. 5 and 6, the pinion  44  has screw threads that engage the teeth  48 , and when the pinion  44  is rotated, the housing  30  will be caused to pivot about the axis of post  34 , and change the angular orientation of the end portion  24  of the flexure unit  20  held by that housing. The thread lead angle of the pinion  44  is such that the housing  30  is held in position, because loads the housing  30  cannot drive the pinion  44  in reverse. The pinion  44  has a drive head  44 H accessible through an opening  27 D in a rear wall  27 C of the recess  27 .  
         [0031]    Again, the housing  30  has side or edge walls  40  that engage and trap edges of the end portions  24  of the flexure unit  20  in position. The end portion  24  of the flexure unit  20  is changed in mounting angle when the housing  30  is adjusted with the pinion and pinion gear.  
         [0032]    In FIG. 7, the gear teeth  48  are shown as well as the interior of the housing  30 .  
         [0033]    In FIG. 8, a perspective view of a base plate  28  is shown, in its preferred form. As can be seen, the post  34  protrudes from the base plate  28  at right angles. It can be seen that the pinion housing  46  has end walls  46 A with recesses  46 B that will receive the center rotatable shaft portion of the pinion  44 . The threads of the pinion fit inside the housing  46 . The relationship between recesses  46 B and the post  34  can be maintained so that the gear teeth  48  of the housing  30  are engaged by the threads on the pinion when post  34  is in the bore  50 .  
         [0034]    In order to adjust the toe lift or assist force, the housings  30  on each side of the orthosis can be pivoted about the axis of the posts  34  on the respective base plate  28 , by rotating the pinions. As shown in FIG. 1, the bottom of foot shell  14  has a lift angle  70  at rest, which is the toe lift, and that angle can be changed by moving the housings  30  on each side of the orthosis. The mounting of the base plates  28  and housings  30  is done so that the axis of pivoting of the center portions of the flexure units  20  is substantially aligned with the axis of movement of the ankle of a wearer. The ankle axis can actually shift slightly as the foot as moved, and by proper adjustment the center portions  22  of the flexures  20  can be aligned appropriately.  
         [0035]    The adjustable mounting housing  30  is preferably on only one of the ends of the flexure units  20 , as shown, but if desired, both ends of each flexure can be adjustably mounted for obtaining adjustable toe lift as shown schematically in FIG. 9 where a lower angle adjustment device  72  is illustrated. The lower adjustment device operates as described. The inner surfaces of the base plates can be suitably padded to provide comfort.  
         [0036]    The base plates  28 , as shown in FIG. 8, also have stop walls  64  along the edges at the ends of the base plate opposite from the pinion housing  46 , to limit the amount of pivotal movement of the mounting housings  30  so that they do not move excessively.  
         [0037]    The edges of the walls  40  of the mounting housing  30  can be flared and radiused to avoid unnecessary wear on the flexure units. The amount of toe lift can be easily adjusted to accommodate individual users.  
         [0038]    Again, mounting housings  30  are used on the opposite sides of one or both of the flexure shells, and certain parts will have to be right and left hand orientation, or in other words mirror images of each other. The base plates  28  and housings  30  can be molded, cast metal, or machined as desired.  
         [0039]    The material used for the flexure units  20  is not critical, as long as the material is elastomeric, and flexible, to permit adequate hinging movement for the orthosis.  
         [0040]    The adjustment devices can be on the exterior of the shells, if desired.  
         [0041]    Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.