Abstract:
The present invention concerns a system that is useful to apply controlled, gradual muscular stretching, and is particularly useful for knee extension therapy.

Description:
TECHNICAL FIELD 
       [0001]    This application relates to a system for stretching a person&#39;s muscles, such as the hamstring muscles as well as the muscles and other tissues comprising the articular capsule of the knee joint. 
       BACKGROUND 
       [0002]    The terms “hamstring,” “hamstrings” or “hamstring muscle” are generally used to refer to the three large muscles constituting the back of the upper leg. The hamstrings serve to flex the knee joint and extend the hip. Everyday activities as well as most athletic activities involve the repetitive contraction of the hamstring muscle. The hamstring muscle tightens as a result, and requires effective stretching to retain its full range of motion. In the absence of such stretching, the tight hamstrings will have a deleterious effect on the person&#39;s skeletal alignment, typically resulting in lower back and knee pain, as well as problems with posture. 
         [0003]    Full extension of the knee is often lost as a result of knee injury and related surgery. Careful and sustained physical therapy is required for a patient after surgery in order to regain full knee extension. A patient can be instructed by a physical therapist as to the proper way to stretch the leg to recover knee extension, and a patient is often left responsible to carry out the therapy on their own at frequent intervals between visits with the physical therapist. 
         [0004]    Stretching any muscle is best done at a slow rate. Attempting to quickly stretch the muscle will rouse the muscle&#39;s inherent tendency to contract when pulled, thereby resisting the sought-after lengthening of the muscle. 
         [0005]    Also, knee extension therapy is often most successful when the stretching applied to the muscles is done in increments separated in time by relaxation of the muscles. This may be referred to as a contraction/relaxation therapy technique. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention concerns a system for knee extension therapy that is useful for controlled, gradual muscular stretching, and is particularly useful for controlled stretching of the hamstring muscle, ligaments, and tendons of the knee, including the entire the articular capsule of the knee joint. 
         [0007]    In a preferred embodiment, the system for knee extension therapy includes an elongated base and a thigh strap configured to strap a patient&#39;s thigh to the base. A boot member is supported on the base to receive the patient&#39;s foot. An expandable member is connected to the boot member and supported by the base away from the thigh strap. The expandable member is configured so that expansion of the expandable member causes movement of the boot member away from the base, thereby forcing extension of the knee. 
         [0008]    In another embodiment, the system can be modified for primarily stretching the hamstring muscles. In this embodiment, the stretched leg extends generally vertically upwardly adjacent to a stationary vertical surface. The stretched leg is supported for controlled, slow, forced rotation about the hip, away from that surface, thereby to stretch the hamstring muscle. 
         [0009]    Preferably, the user of the system is situated so that, apart from the stretched leg, the remainder of the person&#39;s muscle groups are relaxed, thereby allowing a focused effort for stretching the hamstring muscle. 
         [0010]    Other advantages and features of the present invention will become clear upon study of the following portion of this specification and drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0011]      FIG. 1  is a diagram illustrating in a side view one embodiment of a system made in accordance with the present invention. 
           [0012]      FIG. 2  is an enlarged view of an expandable part of the system of  FIG. 1 . 
           [0013]      FIG. 3  is a diagram illustrating in side view a portion of an alternative embodiment of the present invention. 
           [0014]      FIGS. 4A and 4B  are side views showing another embodiment of the present invention. 
           [0015]      FIG. 5A  is a bottom view of the embodiment of  FIGS. 4A and 4B . 
           [0016]      FIG. 5B  is an enlarged detail view taken from  FIG. 5A . 
           [0017]      FIG. 6  is a perspective view showing a portion of another alternative embodiment. 
           [0018]      FIGS. 7A and 7B  are side views showing another embodiment of the invention, comprising a system for knee extension therapy. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0019]    The first portion of this description relates to an embodiment comprising a system made in accordance with the present invention that is amenable for use in yoga exercises or physical therapy, with or without additional components for supporting or isolating the hamstring muscles to be stretched. This embodiment and alternatives are described in the following text associated with  FIGS. 1-6 . That discussion is followed by another embodiment of the invention that supplements the foregoing with the text associated with  FIGS. 7A and 7B , which illustrate the system for knee extension therapy. 
         [0020]      FIG. 1  illustrates a stretching system that is employed by a user  20  for controlled, gradual stretching of the hamstring muscle. The system may be operated while the user  20  is reclined, on his back, with one “rested” leg  22  extending horizontally on a flat surface  28 . The other “stretched” leg  24  is rotated at the hip and extends vertically upwardly, with the knee held straight. The back of the stretched leg  24  is adjacent to the surface of a stationary, rigid member  26 . 
         [0021]    In one embodiment, the member  26  may be an existing doorjamb, which is the vertical component of a door frame. In such an embodiment, the components of the stretching system include an expandable member  30  that will hereafter also be referred to as an expander  30 . The expander  30  is located adjacent to the vertical member  26  between that member and the back of the user&#39;s stretched leg  24 . The expander  30  may abut or be removably attached to the stationary surface of the vertical member. 
         [0022]    The expander  30  is cushioned and/or contoured to comfortably receive the stretched leg, preferably in the vicinity of the user&#39;s Achilles tendon. In this regard, the expander  30  may have a boot-like configuration as shown in  FIG. 2  and discussed more below. 
         [0023]    The expander  30  is controlled for providing incremental or gradual expansion from a contracted position to an expanded position for correspondingly gradual stretching of the user&#39;s hamstring muscle. As one aspect of this invention, the user may maintain the reclined position while remotely controlling the expander  30 . 
         [0024]    In the contracted position of the expander  30 , the user&#39;s stretched leg  24  is generally vertical, thus making an angle “A” of about 90 degrees with the horizontal surface  28 . The contracted position of the expander  30  appears in  FIG. 1  as cross-hatching of the back portion of the expander  30  that is between the leg  24  and the vertical member  26 . Movement of the expander  30  toward the expanded position (shown in dashed lines in  FIG. 1 ) increases the angle between the stretched leg  24  and the surface  28  by angle “B” from vertical. The act of gradually moving the user&#39;s leg  24  through the angle “B” effectively stretches the hamstring muscle of that leg. 
         [0025]    As noted, the expansion of the expander  30  is controlled by the user in a manner that permits the user to maintain an otherwise relaxed, reclined position. To this end, a remote control  32  is positionable near the hand  34  of the user. The expansion of the expander  30  may be provided by a pneumatic system, and the control  32  may comprise a hand pump or other valving that communicates with the expander  30  via line  36  for directing pressurized air into the expander  30  to expand it. The control  32  may also include a release valve for slowly returning the expander to the contracted state upon completion of the desired stretching time. A conventional sphygmomanometer bulb will suffice as the pump and release valve. 
         [0026]    It is also contemplated that the control can be electronically automated with a simple controller for activating an air pump and associated valves for inflating and deflating the expander  30  in accord with built-in or user-defined programming. 
         [0027]      FIG. 2  illustrates in greater detail a preferred embodiment of the expander  30 . In this embodiment, the expander  30  has a boot-like configuration that includes a bottom  42 , a back  44 , and two opposing sidewalls  46 ,  48 . The expander  30  may be formed of, for example, sewn synthetic material, such as nylon, that forms the outer casing for internal cushioning and an expandable air bladder  50 . The bottom  42  of the expander  30  extends across the sole of the user&#39;s foot  25 . The back  44  of the expander  30  extends from the rearward end of the bottom and along the back of the user&#39;s leg  24  generally adjacent to the Achilles tendon. 
         [0028]    The sidewalls  46 ,  48  are attached to or integrally formed with the bottom  42  and back  44  and extend therefrom in a generally parallel relationship across the sides of the user&#39;s foot  25 , ankle, and lower leg. Between the sidewalls  46 ,  48  at the forward edge of the expander  30  (that is, the leftmost side in  FIG. 2 ) there is an open space to permit the user to insert the foot  25  into the expander. Preferably, the sidewalls  46 ,  48  carry one or more straps  52  with associated hook and loop fastening to secure the sidewalls together with the foot inserted into the expander  30 . 
         [0029]    The bottom  42  and sidewalls  46 ,  48  may be filled with cushioning (shown cross-hatched in  FIG. 2 ), such as foam, to provide a snug, comfortable fit when the expander is worn. The back  44  houses the expandable air bladder  50  to which the pneumatic line  36  is coupled. As described above, the system is controlled by the user to direct pressurized air through the line  36  for controlled expansion of the bladder  50  and consequent stretching of the hamstring muscle. 
         [0030]    In a preferred embodiment, the bladder  50  and back  44  are configured so that the portion of the back  44  that is placed in contact with the vertical member  26  remains relatively flat or planar, and the expansion of the bladder  50  is thus primarily directed toward the user&#39;s leg  24 . Moreover, the bladder  50  is shaped so that in expanding away from the stationary surface the bladder enlarges by a progressively greater amount in the direction toward its outermost (upper) part (note the broken line  30  in  FIG. 1 ), so that the portion of the leg that contacts the back  44  of the expander  30  is supported in a generally straight line. 
         [0031]      FIG. 3  shows an alternative embodiment of the invention whereby the vertical member  126  is integrated with the system. In one approach, the vertical member  126  is in a stationary vertical position and carries the expander  30  ( FIGS. 1 and 2 ). Branching from the vertical member is a brace  38  that is configured to provide contact with the knee of user&#39;s rested leg  22 , so that leg  22  does not bend upwardly (as it otherwise tends to do) while the other leg  24  is being stretched. 
         [0032]    As another approach to the integrated vertical member embodiment ( FIG. 3 ), the vertical member  126  is constructed to rotate about a pivot point  40  to provide the user-controlled increase in angle “B” mentioned above. Any suitable pneumatic, hydraulic or mechanical system would be employed for moving the member  126 . This type of movable member could be used without, or in combination with, an expander  30 . 
         [0033]      FIGS. 4A and 4B  illustrate another preferred embodiment of the present invention. These figures show a side view of this embodiment, which includes a rigid, thin back plate  144 . The back plate  144  comprises two layers: a rigid plastic layer  146 , such as acrylonitrile butadiene styrene (ABS) to which is bonded an outer layer  148 , such as polyester felt. The outer layer  148  bears against a stationary surface  150 , such as the surface of a doorjamb, and permits slight vertical sliding movement of the system along the doorjamb without marring that surface. 
         [0034]    It is noteworthy here that the back plate  144  may be constructed in a variety of other configurations. For example, the back plate could be mounted to a vertical pole or other structure in a fitness club and adjustable in height to enable use of the system by users of various heights (that is, leg lengths). It will be appreciated that the presently described embodiment, featuring abutting contact with a doorjamb, for example, provides a readily portable and compact system that may be used in various locations around the user&#39;s house, hotel room, etc. 
         [0035]    A generally U-shaped linkage  152  (see especially,  FIG. 5A ) is pivotally mounted to the back plate  144 . That linkage includes a pair of arms  154 , one arm extending from each of the opposing ends of a connector part  156  of the linkage that extends across the inner surface  158  of the back plate  144 . The connector part  156  is secured by spaced-apart sleeves  157  that are fastened to the back plate  144  to make a hinge-like, pivoting connection of the linkage  152  so that the arms  154  are able to swing about the long axis of the connector part  156  toward and away from the back plate  144 . 
         [0036]    The free end of each arm  154  of the linkage is pivotally attached as at  159  to opposite sides of a boot member  160 . The linkage arms  154  are rigid, preferably metal, and serve to stabilize the position of the boot member  160  relative to the back plate  144 . The linkage  152  also controls or guides the movement of the boot member as it moves away from and toward the plate. 
         [0037]    The boot member  160  may be a molded plastic member, or cut from a flat sheet of plastic (such as polyethylene) and bent and joined to define a bottom  162  and sidewalls  164 ,  166  into which fits the foot  125  of a user. 
         [0038]    One of the sidewalls  164 ,  166  carries a strap  168  with associated hook and loop fastening. The free end of the strap is threaded through an aperture in the other sidewall so that the strap may be folded back on itself to secure the sidewalls together and hold the user&#39;s foot within the boot member  160 . 
         [0039]    The boot member  160  may be formed solely of somewhat rigid plastic or, preferably, lined with foam cushioning to enhance the comfort of the boot member. 
         [0040]    An expandable bladder  170  is connected to the boot member  160  and to the inner surface  158  of the back plate  144 . The bladder  170  is formed or two air-impermeable plastic sheets that are heat-welded together at their peripheral edges. Preferably, the heat-welded edge of the bladder is made wide enough to define a flange  173  ( FIG. 5B ) to which are riveted the male portions  172  of conventional snap fasteners. The male portions  172  on the bladder flange engage corresponding female portions  174  of snap fasteners that are carried on the both the back  176  of the boot member  160  and on the inner surface  158  of the back plate. In this embodiment, two spaced-apart snap fasteners are thus provided for attaching part of the bladder flange  173  to the boot member, and two fasteners are so used to attach another part of the bladder flange to the back plate  144 . It will be appreciated that there may be a variety of alternative ways to attach the bladder between the boot member and back plate. For example, the bladder flange may be stapled or bonded to those respective components. 
         [0041]    A pneumatic line  178  couples to the bladder for conducting air to and from the bladder as discussed above in connection with the earlier-described embodiment. 
         [0042]    It is noteworthy that the bladder  170  is somewhat trapezoidal in shape (See  FIG. 4B ) when fully inflated. In this regard, the bladder  170  is connected along a length of the back  176  of boot member, generally adjacent to the user&#39;s Achilles tendon, and configured to expand between the boot member  160  and the stationary surface  150  by a varying amount along the length of the boot member in the direction toward the heel  180  of the user. This configuration of the bladder, in conjunction with the pivotal connection with the linkage  152 , causes rotation of the boot member as the boot member moves away from the stationary surface so that the stretched leg can be held straight as it rotates about the hip. 
         [0043]      FIG. 6  is an isometric view showing a portion of another alternative embodiment that employs a linkage  182  that is essentially a modification of the linkage  152  described above. The bladder and other components have been omitted for illustration purposes. The modified linkage provides the same stability and guidance as mentioned above, but also provides a relatively greater travel distance for the boot member  184  away from the back plate  186 , thereby to provide a greater amount of muscular stretching. 
         [0044]    The linkage of  FIG. 6  includes two pivotally attached parts: a plate-mounted part  188 , and a boot-mounted part  190 . The plate-mounted part  188  is generally U-shaped and includes a pair of arms  192 , one arm extending from each of the opposing ends of a connector part  194  of the linkage that extends across the inner surface  258  of the back plate  186 . The connector part  194  is secured to the surface  258  by spaced-apart sleeves  196  that are fastened to the back plate  186  to make a hinge-like, pivoting connection of the plate-mounted linkage part  188  so that the arms  192  are free to swing about the long axis of the connector part  194  toward and away from the back plate  186 . 
         [0045]    The free end of each arm  192  is pivotally joined to the U-shaped, boot-mounted part  190  of the linkage at the location  204  where the connector part  200  of that linkage joins the arms  202 . The free ends of those boot-mounted linkage arms  202  are each pivotally attached as at  206  to opposite sides of the boot member  184 . As mentioned, this two-bar linkage  188 , although able to collapse so that the boot member  184  can move adjacent to the back plate  186 , also permits a relatively large travel distance for the boot member away from the back plate. 
         [0046]    Turning now to the embodiment preferred for knee extension therapy, reference is made primarily to  FIGS. 7A and 7B . This system includes a boot member  360  that, unless discussed otherwise below, is constructed like boot member  160  or  184  of the prior embodiments and includes a bottom  362 , and sidewalls  366  between which fits the foot  325  of a user, such as a patient undergoing post-operative knee extension therapy. 
         [0047]    The boot member  360  carries a strap  368  with associated hook and loop fastening. The free end of the strap is threaded through an aperture in the other sidewall so that the strap may be folded back on itself to secure the sidewalls together and hold the user&#39;s foot within the boot member  360 . 
         [0048]    A back plate  344 , like the back plate  144  discussed above, comprises a rigid plastic layer to which is bonded an outer layer, such as polyester felt. The outer layer bears against a thin, rigid base  350 . The base may be, for example, rigid plastic or wood. 
         [0049]    A generally U-shaped linkage (like  152  in  FIG. 5A ) is pivotally mounted to the back plate  344 . That linkage includes a pair of arms; with one arm  354  extending from each of the opposing ends of a connector part of the linkage that extends across the inner surface (that is facing away from the base  350 ) of the back plate  344 . The connector part makes a hinge-like, pivoting connection of the linkage to the back plate  344  so that the arms  354  are able to swing toward and away from the back plate  344 . 
         [0050]    The free end of each arm  354  of the linkage is pivotally attached as at  359  to opposite sides of the boot member  360 . The linkage arms  354  are rigid, preferably metal, and serve to stabilize the position of the boot member  360  relative to the back plate  344 . The linkage also controls or guides the movement of the boot member as it moves away from and toward the back plate. 
         [0051]    An expandable bladder  370  is connected to the boot member  360  and to the inner surface of the back plate  344 . The bladder  370  is preferably formed and attached as discussed above with respect to bladder  170   
         [0052]    A pneumatic line  378  couples to the bladder for conducting air to and from the bladder under the control of the user as discussed above in connection with the earlier-described embodiment. In this embodiment the control for inflating and deflating the bladder is preferably a conventional sphygmomanometer bulb  332  ( FIG. 7B ), that can be squeezed by the patient for inflating the expandable bladder. The bulb  332  includes a normally-closed deflation valve  333  that, upon manipulation by the user, can be opened for venting the bladder  370  to atmosphere and thus allowing the bladder to collapse. 
         [0053]    This embodiment the system also includes a thigh strap  340  that is employed for securing the patient&#39;s leg  324  to the rigid base  350  at the patient&#39;s thigh so that the patient&#39;s knee is between the thigh strap  340  and boot member  360 . The strap  340  may be an suitable material for comfortably securing the leg  324  in place, with sufficient tensile strength for resisting movement of the patient&#39;s thigh away from the base  350  as the bladder  370  ( FIG. 7A ) is fully inflated ( FIG. 7B ). A single woven nylon strap with cooperating hook and loop fastening may be employed. 
         [0054]    With reference to  FIG. 7A , the leg  324  of a patient seeking knee extension therapy is located adjacent to the base  350 , with the foot  325  strapped into the boot member  360 . The patient&#39;s thigh is then snugly strapped  340  to the base. In this position, the patient&#39;s knee is not fully flexed, as illustrated by the knee-extension angle “E” of  FIG. 7A , which is substantially less than 180 degrees. 
         [0055]    The patient then repeatedly squeezes the bulb  332  for gradually inflating the bladder  370 , thereby lifting the boot member  360  (hence the foot  325 ) above the base  350 , while the thigh strap prevents the leg above the knee from lifting from the base. As a result, the hamstring muscle stretches and the tissues surrounding the knee react such that the knee extends to increase the knee-extension angle “E” toward 180 degrees or beyond. 
         [0056]    It will be appreciated that the patient-operated bulb  332  enables the patient to personally control the rate of forced knee extension and attendant pain level. Moreover, the hand manipulated deflation valve  333 , allows the patient to occasionally deflate the bladder for temporarily relaxing the amount of stretch. As a result, the knee extension is done in increments separated in time by relaxation of the muscles to accomplish the contraction/relaxation therapy technique mentioned above. 
         [0057]    It will also be appreciated that the patient may partially extends the knee joint by partly inflating the bladder  370  so that (while the deflation valve  333  is closed) the leg is held in a desirable position for effective isometric training of the affected joint muscles. 
         [0058]    While the present invention has been described in terms of preferred embodiments, it will be appreciated by one of ordinary skill in the art that modifications may be made without departing from the teachings and spirit of the invention. For example, it is contemplated that the back plate  344  be readily removed from the base, and the base  350  may be hinged in one or more locations to enable the base to be made more compact for storage or transportation when not in use. Also, the function of the thigh strap could be accomplished with any of a variety of mechanisms, such as hoops or brackets, for keeping the thigh against the base. The general notion of “strapping” the thigh to the base thus includes such mechanisms. 
         [0059]    Moreover, the air bladder could be replaced with a foam- and/or compression-spring-filled interior that is compressed before use and controlled so that the natural resilience of the foam and/or spring expands the bladder and displaces the boot member from the back plate. A fluid-driven, lightweight telescoping member might also be used alone or with a bladder to expand the distance between the boot member and the back plate.