Patent Publication Number: US-6702768-B2

Title: Foot bending and stretching apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus for forcibly bending a foot about a foot joint of an inferior limb of a living person, while pressing a sole (planta pedis) of the foot, thereby preventing foot-drop (talipes equinus) and deep venous thrombosis. 
     2. Related Art Statement 
     A patient who has been ill in bed for a long time is likely to suffer foot-drop, i.e., the disease that foot joint cannot be bent from its stretched position. Some patients suffer this disease in two weeks only. A patient who suffers foot-drop cannot easily walk and needs a long time to achieve rehabilitation. Thus, it is strongly desirable to prevent foot-drop. Foot-drop can be prevented by sometimes bending the foot. However, many patients who suffer foot-drop cannot bend their feet without help, because of, e.g., paralysis of peroneal nerve. 
     There has been developed no apparatus for preventing foot-drop, and there has been proposed only a training apparatus for restoring the function of a foot suffering foot-drop. For example, Japanese Patent Document No. 9-253144 discloses a function-restoring training apparatus. This training apparatus includes an air bag which is provided in vicinity of an ankle on the side of an instep (dorsum pedis); a support band which has a shape of loop, is wound around a portion of a lower leg located between the ankle and the knee, is connected at one end thereof to the air bag, and fixes the air bag to the ankle; and a tension band which has a shape of loop, is wound around a portion of a sole located between toes and a heel, and is connected at one end thereof to an upper surface of the air bag. When the air bag is charged with air and the air is discharged from the air bag, the air bag pulls, and loosens, the tension band, thereby forcibly bending the foot about the foot joint. 
     It is speculated that if a patient uses the above-indicated function-restoring apparatus before he or she suffers foot-drop, he or she can prevent the disease. On the other hand, a patient who has been ill in bed for a long time is likely to suffer deep venous thrombosis (DVT), i.e., the disease that blood clots develop and float in veins of an inferior limb, and even clog the veins, because his or her blood is likely to stay in the veins. This disease is accelerated if the patient has the problem of abnormal coagulation or dehydration, and may develop in from several hours to one day. 
     There has been proposed an apparatus for preventing the above-indicated deep venous thrombosis. This apparatus includes a support belt which supports an air bag and is worn on a foot of a living person such that the air bag is positioned on the sole of the foot and so that the air bag is supplied with pressurized air and is inflated to press the sole. When a living person walks, venous blood is pumped up from the veins of the sole of foot by the pressure caused by load, and is conveyed from the inferior limb to the heart. However, a patient who has been ill in bed for a long time is short of the pressure applied to his or her sole and accordingly is likely to suffer venous thrombosis. Hence, if the above-indicated apparatus is used to press the sole, deep venous thrombosis can be prevented. However, the apparatus that can only press sole cannot prevent foot-drop. 
     Thus, according to the conventional art, both a foot-drop preventing apparatus and a deep-venous-thrombosis preventing apparatus must be used to prevent foot-drop and deep venous thrombosis. That is, first, a patient wears the foot-drop preventing apparatus on his or her foot, performs a prescribed operation to prevent foot-drop, then puts the apparatus off the foot, subsequently wears the deep-venous-thrombosis preventing apparatus on the foot, and then performs a prescribed operation to prevent deep venous thrombosis. These actions are very cumbersome and time-consuming. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide an apparatus for simultaneously preventing foot-drop and deep venous thrombosis. 
     The above object has been achieved by the present invention. According to a first feature of the present invention, there is provided an apparatus for bending and stretching a foot of a living person by pressing at least an arch of a sole of the foot and stopping the pressing of the arch. 
     According to this feature, while at least the arch of the foot is pressed, the foot is bent; and when the pressing of the arch is stopped, the foot is naturally returned to its stretched state. When these actions are repeated, the bending and stretching of the foot are repeated. Thus, the foot is prevented from foot-drop. In addition, since at least the arch of the foot is pressed while the foot is bent, the foot is prevented from deep venous thrombosis. 
     According to a second feature of the present invention, there is provided an apparatus for bending and stretching a foot of a living person, comprising a pressurized-gas supplying device which supplies a pressurized gas; and an inflatable bag which is provided in vicinity of an arch of a sole of the foot, and is inflated by the pressurized gas supplied by the pressurized-gas supplying device, so as to press at least the arch of the sole of the foot. 
     According to this feature, when the inflatable bag is inflated by the pressurized gas supplied by the pressurized-gas supplying device, the inflated bag presses at least the arch of the sole, thereby bending the foot. When the inflation of the bag is stopped, the pressing of the sole is also stopped, so that the foot is naturally returned to its stretched state. Since the foot can be iteratively bent and stretched by repeating these actions, the foot can be prevented from foot-drop. In addition, since at least the arch of the foot is pressed while the foot is bent, the foot is prevented from deep venous thrombosis. 
     According to a third feature of the present invention, there is provided an apparatus for bending and stretching a foot of a living person, comprising a support plate including a base portion which is adapted to be worn on a lower portion of an inferior limb of the person such that the base portion is not movable relative to the inferior limb, and an end portion which is inclined relative to the base portion in a direction away from the foot of the inferior limb and is opposed to an instep of the foot; an inflatable bag which is provided on one of opposite sides of the end portion of the support plate that is opposite to the instep; a pressurized-gas supplying device which supplies a pressurized gas to the inflatable bag; a pressing member which is provided in vicinity of an arch of a sole of the foot; and a binding member which binds the end portion of the support plate, the inflatable bag, and the pressing member, around the foot, such that the bag is inflatable by the pressurized gas supplied by the pressurized-gas supplying device. 
     According to this feature, the binding member binds the end portion of the support plate, the inflatable bag, and the pressing member, around the foot. Therefore, if the bag is inflated inside the binding member, the pressing member presses at least the arch of the sole and simultaneously the pressing member and the foot are moved toward the end portion of the support plate. In addition, since the base portion of the support plate is fixed to the lower leg and the end portion thereof is inclined relative to the base portion in a direction away from the foot, the foot is bent when the inflatable bag is inflated and the foot is moved toward the end portion. Moreover, when the inflation of the bag is stopped, the pressing member also stops pressing the sole, so that the foot is naturally returned to its stretched state. Since the foot can be iteratively bent and stretched by repeating these actions, the foot can be prevented from foot-drop. In addition, since at least the arch of the foot is pressed while the foot is bent, the foot is prevented from deep venous thrombosis. 
     According to a fourth feature of the present invention, there is provided an apparatus for bending and stretching a foot of a living person, comprising an inflatable bag which is opposed to an instep of the foot and a shin of a lower portion of an inferior limb of the person, the inflatable bag including a first portion which is opposed to the instep and is deformed, when the bag is inflated, to form a curved portion, the inflatable bag additionally including a second portion which is opposed to the lower portion and is worn on the lower portion such that the second portion is not movable relative to the lower portion; a pressurized-gas supplying device which supplies a pressurized gas to the inflatable bag; a pressing member which is provided in vicinity of a sole of the foot; and a connecting member which connects the inflatable bag and the pressing member to each other such that a distance between the inflatable bag and the pressing member is substantially unchangeable. 
     According to this feature, a portion of the inflatable bag is opposed, and fixed, to the lower leg, and the distance between the inflatable bag and the pressing member is kept unchanged by the connecting member. Therefore, when the inflatable bag is inflated and accordingly a portion of the bag that is opposed to the instep is deformed to form a curved portion, the pressing member is moved toward the sole to press the sole and thereby bend the foot. Meanwhile, when the inflation of the bag is stopped, the pressing member also stops pressing the sole, so that the foot is naturally returned to its stretched state. Since the foot can be iteratively bent and stretched by repeating these actions, the foot can be prevented from foot-drop. In addition, since at least the arch of the foot is pressed while the foot is bent, the foot is prevented from deep venous thrombosis. 
     According to a fifth feature of the present invention, there is provided an apparatus for bending and stretching a foot of a living person, comprising a bending device including an elongate flexible plate and a bellows tube held in close contact with the flexible tube, the bellows tube being opposed to an instep of the foot, one of lengthwise opposite end portions of the bending device being worn on a shin of a lower portion of an inferior limb of the person such that the one end portion of the bending device is not movable relative to the lower portion; a pressurized-gas supplying device which supplies a pressurized gas to the bellows tube of the bending device; a pressing member which is provided in vicinity of a sole of the foot; and a connecting member which connects the bending device and the pressing member to each other such that a distance between the bending device and the pressing member is substantially unchangeable. 
     According to this feature, when the bellows tube is supplied with the pressurized gas and is inflated, the flexible plate is so curved that the curved flexible plate is located inside the inflated bellows tube. Since one of lengthwise opposite end portions of the bending device is fixed to the shin of the lower leg, a portion of the bending device that is opposed to the instep is curved in a direction away from the instep, when the bending device is curved. In addition, since the distance between the bending device and the pressing member is kept unchanged by the connecting member. Therefore, when the bending device is curved in a direction away from the instep, the pressing member presses the sole and thereby bends the foot. Meanwhile, when the pressurized gas is discharged from the bellows tube, the pressing member also stops pressing the sole, so that the foot is naturally returned to its stretched state. Since the foot can be iteratively bent and stretched by repeating these actions, the foot can be prevented from foot-drop. In addition, since at least the arch of the foot is pressed while the foot is bent, the foot is prevented from deep venous thrombosis. 
     According to a sixth feature of the present invention, the foot bending and stretching apparatus further comprises an annular inflatable bag which is adapted to support a heel of the foot, the annular bag being inflated to lift the heel off a floor. 
     When the annular bag of this foot bending and stretching apparatus is inflated, the heel is lifted off the floor. When the heel is sometimes lifted off the floor, the foot can be prevented from bedsore. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and optional objects, features, and advantages of the present invention will be better understood by reading the following detailed description of the preferred embodiments of the invention when considered in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a view for explaining a construction of a foot bending and stretching apparatus to which the present invention is applied; 
     FIG. 2 is a block diagram for explaining a construction of an air charging and discharging device shown in FIG. 1; 
     FIG. 3A is a view of a first pressure-increase pattern pre-stored in a ROM shown in FIG. 2; 
     FIG. 3B is a view of a second pressure-increase pattern pre-stored in the ROM; 
     FIG. 3C is a view of a third pressure-increase pattern pre-stored in the ROM; 
     FIG. 3D is a view of a fourth pressure-increase pattern pre-stored in the ROM; 
     FIG. 4A is a view showing a state in which a bending and stretching device shown in FIG. 1 is worn on an inferior limb of a patient who is taking a face-up position and an air bag of the apparatus is fully inflated; 
     FIG. 4B is a view showing a state in which the bending and stretching device is worn on the inferior limb and the air bag of the device is fully deflated; 
     FIG. 5A is a view showing a state in which a bending and stretching device of another foot bending and stretching apparatus as a second embodiment of the present invention is worn on an inferior limb and a foot of the limb is bent by the bending and stretching device; 
     FIG. 5B is a view showing a state in which the bending and stretching device is worn on the inferior limb and the foot is stretched by the bending and stretching device; 
     FIG. 6A is a view showing a state in which a bending and stretching device of another foot bending and stretching apparatus as a third embodiment of the present invention is worn on an inferior limb and a foot of the limb is bent by the bending and stretching device; 
     FIG. 6B is a view showing a state in which the bending and stretching device is worn on the inferior limb and the foot is stretched by the bending and stretching device; 
     FIG. 7A is a view showing a state in which a bending and stretching device of another foot bending and stretching apparatus as a fourth embodiment of the present invention is worn on an inferior limb and a foot of the limb is stretched by the bending and stretching device; 
     FIG. 7B is a view showing a state in which the bending and stretching device is worn on the inferior limb and the foot is bent by the bending and stretching device; and 
     FIG. 8 is a view of a bending and stretching device of another foot bending and stretching apparatus as a fifth embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Hereinafter, there will be described a preferred embodiment of the present invention in detail by reference to the accompanying drawings. FIG. 1 shows a view for explaining a construction of a foot bending and stretching apparatus  10  to which the present invention is applied. The apparatus  10  includes a bending and stretching device  12  which is adapted to be worn on an inferior limb, not shown, of a living person, and an air charging and discharging device  14 . 
     The bending and stretching device  12  includes an elongate support plate  16  which has a considerably high rigidity and supports the inferior limb, not shown. The support plate  16  has a length of from 30 to 80 cm, and a width (e.g., from 20 to 30 cm) slightly greater than a width of a lower leg (i.e., a portion of a leg between its knee and its foot joint). An air bag  18  functioning as a gas bag is fixed to one of lengthwise opposite end portions of the support plate  16 . In a state in which the air bag  18  is fully inflated, the air bag  18  takes a generally cylindrical shape. The air bag  18  has an axial length substantially equal to the width of the support plate  16 , so that opposite end walls  20  of the air bag  18  are substantially aligned with opposite long sides of the support plate  16 , respectively. The diameter of the cylindrical shape taken by the air bag  18  is equal to from one third, to a full size, of a foot of a common adult person. 
     The air bag  18  has a foot fastening  24  which is engageable with an instep of a foot, not shown, of the person, so as to fasten the foot against a cylindrical surface  22  of the bag  18 . The pedal belt  24  is provided at a position on the cylindrical surface  22  that is distant from a top position of the surface  22  by a distance equal to from one sixth to one fourth of a circumferential length of the surface  22  in a direction toward the other end portion of the support surface  16  that is opposite to the one end portion thereof to which the air bag  18  is fixed. An air hose  26  is connected to one of the two end walls  20  of the air bag  18 , so as to be communicated with an inner space of the air bag  18 . 
     An annular bag  28  is fixed to an upper surface of the support plate  16 , such that an axis of the annular bag  28  is perpendicular to the support plate  16 . The annular bag  28  is provided at a widthwise, substantially middle position on the support plate  16 , and at a position distant from the position where the air bag  18  is fixed, by a distance equal to from the radius, to the diameter of, the air bag  18 , in the direction toward the above-indicated other end portion of the support surface  16 . The annular bag  28  supports a heel of the foot, not shown, such that the heel fits in an inner space of the annular bag  28 . The position where the annular bag  28  is provided is so determined that when the heel fits in the annular bag  26 , the arch of the foot can contact the cylindrical surface  22  of the air bag  18 . The annular bag  28  has a diameter (e.g., 5 cm) which is equal to, or greater by several centimeters than, the diameter of a circle of substantially the same size as that of an area of the heel that supports the weight of the heel in a state in which the person is taking a face-up position. The annular bag  28  has an axial length, e.g., 5 cm, which assures that when the annular bag  28  is fully inflated, the heel supported thereby does not contact the support plate  16 . The air hose  26  is connected to the annular bag  28  via a branch pipe  30 . 
     The support plate  16  has, at a lengthwise, substantially middle position thereof, a pair of lower-leg fastening belts  32  whose respective one ends are fixed to the plate  16 , such that each of the fastening belts  32  extends in a direction substantially perpendicular to the lengthwise direction of the plate  16 . The fastening belts  32  are wound around a portion of the lower leg, not shown, to fasten the lower leg against the support plate  16 . A mail fastener sheet  34  is adhered to an inner surface of a free end portion of one of the two belts  32 , and a female fastener sheet  36  is adhered to an outer surface of a free end portion of the other belt  32 . 
     The air charging and discharging device  14  includes an operation panel  38  which has a highest-pressure setting knob  40  which is operable for setting a highest air pressure P MAX  (Pa) in the air bag  18 ; a pressure-increase-pattern setting knob  42  which is operable for setting a pressure-increase pattern according to which the air pressure is increased up to the highest air pressure P MAX ; a time-interval setting knob  44  which is operable for setting a time interval from the end of one pressure increasing operation to the start of another pressure increasing operation; a start button  46  which is operable for starting a pressure increasing operation to increase the air pressure of the air bag  18 ; a stop button  48  which is operable for stopping a pressure increasing operation; and a display device  50  which displays the air pressure in the air bag  18 , etc. 
     FIG. 2 is a diagrammatic view for explaining a construction of the air charging and discharging device  14 . In FIG. 2, an air pump  52 , an air-discharge valve  54 , and a pressure sensor  56  are connected to one another via a piping  58 . A connection end of the piping  58  is connected to the air hose  26 . The air pump  52  functions as a pressurized-gas supplying device which supplies a pressurized air to the air bag  18  and the annular bag  28  via the piping  58  and the air hose  26 . The air-discharge valve  54  discharges the pressurized air from the air bag  18 . The pressure sensor  56  detects an air pressure in the piping  58 , i.e., an air pressure in the air bag  18 , and supplies a detection signal representing the detected air pressure, to a control device  62  via an A/D (analog-to-digital) converter  61 . 
     The control device  62  is provided by a so-called microcomputer including a CPU (central processing unit)  64 , a ROM (read only memory)  66 , a RAM (random access memory)  68 , and an I/O (input-and-output) port, not shown. The CPU  64  processes signals according to the control programs pre-stored in the ROM  66  by utilizing the temporary-storage function of the RAM  68 , and controls the air pump  52  and the air-discharge valve  54  to increase the pressure in the air bag  18 , up to the highest pressure PMAX set by the highest-pressure setting knob  40 , according to the pressure-increase pattern selected by the pressure-increase-pattern setting knob  40  from a plurality of pressure-increase patterns pre-stored in the ROM  66 . FIGS. 3A,  3 B,  3 C, and  3 D show the stored pressure-increase patterns, respectively. 
     FIGS. 4A and 4B show respective states in which the bending and stretching device  12  is worn on an inferior limb  72  of a patient  70 . More specifically described, FIG. 4A shows a state in which the air bag  18  is fully inflated; and FIG. 4B shows a state in which the air bag  18  is fully deflated. In FIGS. 4A and 4B, the air hose  26  and the branch pipe  30  are omitted. In the state, shown in FIG. 4B, in which the air bag  18  is fully deflated, a foot  74  is stretched and is placed on the air bag  18 . As the pressurized air is supplied, in this state, to the air bag  18 , the bag  18  is inflated to press an arch of a sole  76  of the foot  74  placed on the bag  18 , in a circumferential direction of a circle whose center is on a foot joint  78 , so that because of the pressing force, the foot  74  is bent eventually to the state shown in FIG.  4 A. When the air bag  18  is supplied with the pressurized air, simultaneously the annular bag  28  is inflated to lift a heel  80  off the support plate  16 . 
     As is apparent from the foregoing description of the foot bending and stretching apparatus  10 , when the air bag  18  is inflated by the air pump  52 , the air bag  18  presses the arch of the sole  76  of the foot  74  and thereby bends the foot  74 . In addition, when the inflation of the air bag  18  is stopped, the pressing of the sole  76  is also stopped, so that the foot  74  is naturally returned to the stretched state. When the present apparatus  10  repeats this operation, the foot  74  is iteratively bent and stretched. Thus, the foot  74  can be prevented from foot-drop. Moreover, since the arch of the sole  76  is pressed while the foot  74  is bent, the foot  74  is also prevented from deep venous thrombosis. 
     In addition, in the foot bending and stretching apparatus  10 , when the annular bag  28  is inflated, the heel  80  is lifted off the floor. If the heel  80  is frequently lifted off in this may, the foot  74  is prevented from bed sore. 
     Next, there will be described a second embodiment of the present invention. In the following description, the same reference numerals as used in the preceding, first embodiment shown in FIGS. 1,  2 ,  3 A to  3 D,  4 A, and  4 B are used to designate the corresponding elements of the present embodiment, and the description thereof is omitted. 
     FIGS. 5A and 5B show a state in which a bending and stretching device  90  which may be employed in place of the bending and stretching device  12  in the first embodiment shown in FIG. 1 is worn on a lower leg  92  of a living person. More specifically described, FIG. 5A shows a state in which a foot  74  is bent by the bending and stretching device  90 , and FIG. 5B shows a state in which the foot  74  is stretched by the device  90 . 
     The bending and stretching device  90  includes a support plate  94  which is adapted to be worn on a shin of the lower leg  92 . The support plate  94  is provided by an elongate plate having a considerably high rigidity, and includes a base portion  96  which is adapted to be worn on the shin; an end portion  98  which is inclined by from 20 to 90 degrees (e.g., 45 degrees) with respect to the base portion  96 , in a direction away from the foot  74 , and which is opposed to an instep  97  of the foot  74  when the foot  74  is bent; and a tip portion  99  which is located at an end of the end portion  98  and is inclined with respect to the end portion  98  in a direction away from the foot  74 . The support plate  94  has a width substantially equal to that of the lower leg  92 . 
     A buffer member  100  is fixed to a lower surface of the base portion  96  of the support plate  94 , and is positioned between the support plate  94  and the shin of the lower leg  92 . The buffer member  100  is larger than a portion of the support plate  94  that contacts the lower leg  92 . In addition, a fastening belt  102  is fixed to an upper surface of the base portion  96  of the support plate  94  and, when the fixing belt  102  is wound around the lower leg  92 , the support plate  94  is attached to the lower leg  92  with the buffer member  100  being interposed between the plate  94  and the leg  92 . 
     An air bag  104  functioning as a gas bag is fixed to one of opposite surfaces of the end portion  98  of the support plate  94  that is opposite to the other surface that is opposed to the foot  74 . The air bag  104  is connected to an air hose  26  and is supplied with a pressurized air from an air pump  52  of an air charging and discharging device  14  (shown in FIG.  1 ). The air bag  104  has such a shape (e.g., a spherical shape) which assures that the air bag  104  is inflated in a direction substantially perpendicular to the end portion  98  of the support plate  94 . 
     A cushion member  106  is fixed to the other surface of the end portion  98  of the support member  94  that is opposed to the instep  97  of the foot  74 . The cushion member  106  has a great expansion and contraction efficiency and is considerably soft. In addition, a pressing air bag  108  functioning as a pressing member is provided in the vicinity of an arch of a sole  76 , so that the air bag  108  contacts the arch. The air bag  108  is connected to the air hose  28  via a branch pipe  30 . Thus, the two air bags  104 ,  108  are concurrently inflated and deflated. 
     The air bag  104  is provided between the end portion  98  of the support plate  94  and a first rectangular plate  110 , and the pressing air bag  108  is provided between the sole  76  and a second rectangular plate  112 . Each of the two rectangular plates  110 ,  112  has a considerably high rigidity, and has a width substantially equal to that of the foot  74  and a length equal to from one third to two thirds of that of the foot  74 . The air bag  108  is fixed to the second plate  112 . 
     A binding belt  114  as a binding member binds the rectangular plate  110 , the air bag  104 , the end portion  98  of the support plate  94 , the cushion member  106 , the foot  74 , the pressing air bag  108 , and the rectangular plate  112 , with one another, in such a manner that the air bag  104  is inflatable. That is, the rectangular plate  110 , the air bag  104 , the end portion  98  of the support plate  94 , the cushion member  106 , the pressing air bag  108 , and the rectangular plate  112  are worn on the foot  74 , with the help of the binding belt  114 , such that the air bag  104  is inflatable. The binding belt  114  includes an engaging portion  116  which extends from a sole-side portion thereof and engages a heel  80  of the foot  74 , so as to prevent the binding belt  114  from coming off the foot  74 . 
     The present foot bending and stretching apparatus includes the bending and stretching device  90  constructed as describe above, and the air charging and discharging device  14  connected to the device  90 . Since, in this apparatus, the end portion  98  of the support plate  94 , the air bag  104 , the pressing air bag  108 , and the foot  74  are bound by the binding belt  114 , the pressing air bag  108  presses the arch and other portion of the sole  76 , and the pressing air bag  10  and the foot  74  move toward the end portion  98  of the support plate  94 , when the air bag  104  is inflated inside the binding belt  114 . In addition, since the base portion  96  of the support plate  94  is fixed to the lower leg  92  and the end portion  98  is inclined relative to the base portion  96  in a direction away from the foot  74 , the foot  74  is bent when the air bag  104  is inflated and the foot  74  moves toward the end portion  98  of the support plate  94 . Meanwhile, when the inflation of the air bag  104  is stopped, the pressing air bag  108  also stops pressing the sole  76 , so that the foot  74  is returned to its stretched state. When these actions are repeated, the foot  74  is repetitively bent and stretched and accordingly is prevented from foot-drop. Moreover, since the arch and other portion of the sole  76  is pressed while the foot  74  is bent, the foot  74  is also prevented from deep venous thrombosis. 
     Next, there will be described a third embodiment of the present invention. FIGS. 6A and 6B show a state in which a bending and stretching device  120  which may be employed in place of the bending and stretching device  12  in the first embodiment shown in FIG. 1 is worn on a lower leg  92  of a living person. More specifically described, FIG. 6A shows a state in which a foot  74  is bent by the bending and stretching device  120 , and FIG. 6B shows a state in which the foot  74  is stretched by the device  120 . 
     The bending and stretching device  90  includes a foot belt  124 , a considerably soft, rectangular top plate  126 , a flexible, rectangular bottom plate  128 , a generally cylindrical air bag  130  functioning as a gas bag, and a pressing air bag  132  functioning as a pressing member. The foot belt  124  is wound around a foot  74 , a foot joint  78 , and a lower portion of a lower leg  92 , in such a manner that toes  122  and a heel  80  of the foot  74  are exposed. The top plate  126  is adhered to an outer surface of an instep-side portion of the foot belt  124 . The bottom plate  128  is adhered to an outer surface of a sole-side portion of the foot belt  124 . The air bag  130  is adhered to an outer surface of the top plate  126 , such that an axis of the cylindrical air bag  130  is perpendicular to a lengthwise direction of the top plate  126 . The pressing air bag  132  is fixed to an inner surface of the sole-side portion of the foot belt  124 , at a position where the air bag  132  contacts an arch of a sole  76 . Thus, the air bag  130  is fixed via the top plate  126  to a portion of the foot belt  124  is opposed to the lower leg  92 . The foot belt  124  is formed of a material having a considerably low degree of stretch, so that a distance between the top plate  126  or the air bag  130  adhered to the plate  126 , and the bottom plate  128  is kept substantially unchanged. Thus, in the present embodiment, the foot belt  124  functions as a connecting member. 
     An air hose  26  is connected to the air bag  130 , and an air pump  52  of the air charging and discharging device  14  supplies a pressurized air to the air bag  130  via the air hole  26 , so as to inflate the air bag  130 . In addition, a branch pipe  130  is connected to the pressing air bag  132 , so that the pressing air bag  132  is inflated together with the air bag  130 . 
     Since the air bag  130  has a cylindrical shape, when the pressurized air is supplied to the air bag  130  in its deflated state shown in FIG. 6B, so as to inflate the air bag  130 , a surface of the air bag  130  that is adhered to the top plate  126  is deformed to form a curved surface  134 , as shown in FIG.  6 A. 
     The present foot bending and stretching apparatus includes the bending and stretching device  120  constructed as describe above, and the air charging and discharging device  14  connected to the device  120 . Since, in this apparatus, the air bag  130  and the pressing air bag  132  are connected to each other by the foot belt  124 , such that the distance between the two air bags  130 ,  132  is kept substantially unchanged, the pressing air bag  132  presses the sole  76 , and thereby bends the foot  74 , when the air bag  130  is inflated and accordingly the portion of the air bag  130  that is opposed to the instep  97  is deformed to form the curved surface  134 . Meanwhile, when the inflation of the air bag  130  is stopped, the pressing air bag  132  also stops pressing the sole  76 , so that the foot  74  is naturally returned to its stretched state. When these actions are repeated, the foot  74  is repetitively bent and stretched and accordingly is prevented from foot-drop. Moreover, since the arch and other portion of the sole  76  is pressed while the foot  74  is bent, the foot  74  is also prevented from deep venous thrombosis. 
     Next, there will be described a fourth embodiment of the present invention. FIGS. 7A and 7B show a state in which a bending and stretching device  140  which may be employed in place of the bending and stretching device  12  in the first embodiment shown in FIG. 1 is worn on a lower leg  92  of a living person. More specifically described, FIG. 7A shows a state in which a foot  74  is stretched by the bending and stretching device  140 , and FIG. 7B shows a state in which the foot  74  is bent by the device  140 . 
     The bending and stretching device  140  includes a bending device  142 ; a flexible rectangular bottom plate  144 ; and a connecting member  146 . The bending device  142  is opposed to an instep  97 , a foot joint  78 , and a lower portion of a shin of the lower leg  92 . The bottom plate  144  is opposed to toes  122 , a sole  76 , and a heel  80 . The connecting member  146  connects between respective toe-side end portions of the bending device  142  and the bottom plate  144 . The connecting member  146  is formed of a material having a considerably high degree of rigidity and a considerably low degree of stretch, and includes a main portion  148  which is opposed to the toes  122 , and two projecting portions  150 ,  152  which project toward the bending device  142  and the bottom plate  144  and are fixed to respective outer surfaces of those elements  142 ,  144 . 
     A cushion member  154  is adhered to an inner surface of an end portion of the bending device  142  that is located on the side of the foot joint  78 . A fastening belt  156  is fixed to the end portion of the bending device  142 , and is wound around the lower leg  92  to fasten the end portion of the bending device  142  via the cushion member  154  to the lower leg  92 . 
     The bending device  142  includes an elongate flexible plate  158 , and a bellows tube  160  which is closely adhered to an inner surface of the flexible plate  158  that is opposed to the instep  97 . A plurality of bellows tubes  160  may be employed and provided such that the bellows tubes  160  extend parallel to each other. The flexible plate  158  includes a base portion  162  to which the fastening belt  156  is fixed; and a main portion  164  which is inclined, with respect to the base portion  162 , by an angle (e.g., from 5 to 20 degrees) substantially equal to an angle by which the foot  74  in its stretched state is inclined with respect to the lower leg  92 , in a direction in which the foot  74  is bent from its stretched state. One end of the bellows tube  160  is contiguous with the cushion member  154 , and an air hose  26  is connected to the one end of the bellows tube  160 . The bellows tube  160  has, in its deflected state, a length substantially equal to that of the main portion  164  of the flexible plate  158 , and has, in its inflated state, a length longer than that of the main portion  164 . 
     When an air pump  52  of the air charging and discharging device  14  supplies a pressurized air to the bellows tube  160  of the bending device  142 , the bellows tube  160  is expanded in its lengthwise direction, so that a free end portion of the tube  160  contacts the main portion  148  of the connecting member  146 . When the pressurized air is further supplied to the bellows tube  160 , the flexible plate  158  of the bending device  142  is deformed, i.e., is curved outward in a direction away from the instep  97 , because of a difference between respective expansion amounts of the bellows tube  160  and the flexible plate  158 , that is, the same principle as the principle of operation of a bimetal. 
     A pressing air bag  166  functioning as a pressing member is fixed to an inner surface of the bottom plate  144 , at a position where the air bag  166  contacts an arch of the sole  76 . A branch pipe  30  is connected to the pressing air bag  166 . Thus, the pressing air bag  166  is inflated together with the bellows tube  160 . A bottom-plate fastening belt  168  is fixed, at one end thereof, to a heel-side end portion of the bottom plate  144 , and is fixed, at the other end thereof, to a shin-side end portion of the fastening belt  156 . Thus, the bottom-plate fastening belt  168  prevents the heel-side end portion of the bottom plate  144  from being separate from the heel  80 . The bottom-plate fastening belt  168  includes an engaging belt  170  which is fixed to a heel-side portion of the fastening belt  168 , and engages the heel  80  to prevent the bending and stretching device  140  from coming off the foot  74 . 
     The present foot bending and stretching apparatus includes the bending and stretching device  140  constructed as describe above, and the air charging and discharging device  14  connected to the device  140 . When the bellows tube  160  is supplied with the pressurized air from an air pump  52  of the air charging and discharging device  14 , and accordingly is inflated, the flexible plate  158  of the bending device  142  is curved outward. Since the bending device  142  is fixed, at one of the lengthwise opposite ends thereof, to the shin-side portion of the lower leg  92 , the flexible plate  158  is curved outward means that the portion of the flexible plate  158  that is opposed to the instep  97  is curved in a direction away from the instep  97 . In addition, since the bending device  142  and the pressing air bag  166  are connected to each other by the connecting member  146  such that the distance between the two elements  142 ,  166  is kept substantially unchanged, that the flexible plate  158  is curved in the direction away from the instep  97  means that the pressing air bag  166  presses the sole  76 , and thereby bends the foot  74  about the joint  78 . Meanwhile, when the inflation of the bellows tube  160  is stopped, the pressing air bag  166  also stops pressing the sole  76 , so that the foot  74  is returned to its stretched state. When these actions are repeated, the foot  74  is repetitively bent and stretched and accordingly is prevented from foot-drop. Moreover, since the arch and other portion of the sole  76  is pressed while the foot  74  is bent, the foot  74  is also prevented from deep venous thrombosis. 
     Next, there will be described a fifth embodiment of the present invention. FIG. 8 shows a state in which a bending and stretching device  180  which may be employed in place of the bending and stretching device  12  in the first embodiment shown in FIG. 1 is worn on a leg of a living person. The bending and stretching device  180  employs an air bag  182  including a bellows  188 , in place of the generally cylindrical air bag  18  of the bending and stretching device  12  shown in FIG.  1 . Thus, in the present embodiment, the air bag  182  functions as a gas bag. 
     The air bag  182  has a top surface  184  on which a foot  74  is placed, and a bottom surface, not shown, which is fixed to a support plate  16 . Each of the top surface  184  and the bottom surface has a generally semicircular shape. A chord  186  of the top surface  184  also defines a chord of the bottom surface. Thus, the top surface  184  is pivotable about the chord  186  as a pivot axis relative to the bottom surface. The bellows  188  provides a side surface connecting between the top surface  184  and the bottom surface, and thereby defines a locus of pivotal movement of the top surface  184  relative to the bottom surface. The top surface  184 , the bottom surface, and the bellows  188  cooperate with one another to provide the air bag  182 . 
     A projection member  190  which is formed of a considerably hard material is fixed to the top surface  184 , at a position where the projection member  190  contacts an arch of a sole  76 . A pair of foot fastening belts  192  are provided on both sides of the projection member  190 , such that respective one ends of the two belts  192  are fixed to a peripheral edge of the top surface  182 . 
     An air hose  26  is connected to the air bag  182  and, when an air pump  52  of an air charging and discharging device  14  supplies a pressurized air to the air bag  182  via the air hose  26 , the air bag  182  is inflated, so that the top surface  184  is pivoted about the chord  186  in a direction away from the bottom surface, not shown. Thus, the air bag  182  presses the arch and other portion of the sole  76  of the foot  74  placed on the top surface  184 , indirectly via the projection member  190 , so that the foot  74  is bent about the joint  78 . 
     The present foot bending and stretching apparatus includes the bending and stretching device  180  constructed as describe above, and the air charging and discharging device  14  connected to the device  180 . When the air bag  182  is supplied with the pressurized air from the air pump  52 , and accordingly is inflated, the air bag  182  indirectly presses the arc and other portion of the sole  76 , thereby bends the foot  74 . Meanwhile, when the inflation of the air bag  182  is stopped, the pressing of the sole  76  is also stopped, so that the foot  74  is returned to its stretched state. When these actions are repeated, the foot  74  is repetitively bent and stretched and accordingly is prevented from foot-drop. Moreover, since the arch and other portion of the sole  76  is pressed while the foot  74  is bent, the foot  74  is also prevented from deep venous thrombosis. 
     While the present invention has been described in its preferred embodiments by reference to the drawings, it is to be understood that the invention may otherwise be embodied. 
     For example, in each of the second to fourth embodiments, the pressing air bag  108 ,  132 ,  166  which is inflated by the pressurized air is employed as the pressing member and, in the fifth embodiment, the projection member  190  which has a considerably high rigidity and has a shape corresponding to the arch of the foot  74  is employed as the pressing member. However, in each of the second to fourth embodiments, the air bag  108 ,  132 ,  166  may be replaced with the projection member  190 . 
     In the third embodiment shown in FIGS. 6A and 6B, the cylindrical air bag  130  is employed. However, since it is required that only the portion of the air bag  130  that is opposed to the instep  97  be deformed, when the bag  130  is inflated, so as to form the curved surface  134 , the cylindrical air bag  130  may be replaced with a semi-cylindrical air bag having a shape obtained by cutting a cylinder along a plane passing through its axis. 
     In each of the illustrated embodiments, the air pump  52  is employed as a pressurized-gas supplying device. However, a pressurized-air supplying piping which is provided in each ward may be used as the pressurized-gas supplying device. In addition, the pressurized gas may be different from the pressurized air, for example, pressurized carbonic acid gas or nitrogen gas. In the latter case, a gas cylinder in which pressurized carbonic acid gas or nitrogen gas is charged, or a piping which supplies pressurized carbonic acid gas or nitrogen gas is used as the pressurized-gas supplying device. 
     It is to be understood that the present invention may be embodied with other changes, improvements and modifications that may occur to a person skilled in the art without departing from the spirit and scope of the invention defined in the appended claims.