BACKGROUND TO THE INVENTION Circulatory ailments generally relate to disorders in the blood circulation system, and one common circulatory ailment is deep vein thrombosis (DVT). DVT is a condition that typically occurs when a blood clot develops in a vein, and usually occurs in the veins of the lower legs. A clot, so formed, will not only result in potentially severe pain and discomfort, but can also be life threatening. If a clot is large enough it may start to interfere with the circulation of blood in the affected area, and even block blood flow from the legs to the heart. In addition a blood clot may become dislodged from the vein where it was formed, and travel to the lungs with potentially fatal consequences.

Various factors may influence and prompt the formation of blood clots in veins. Of major concern is the forming of blood clots due to pooling of blood in the veins, which may in turn be caused by insufficient blood circulation. When a person, for instance, remains immobile for prolonged periods, the inactivity of the leg muscles may cause the natural pumping action caused by flexing and relaxing of the calf muscles to cease, thus resulting in pooling of the blood. The probability of the occurrence of DVT will further be increased by the presence of inherent risk factors, for example the use of medication that may render the blood more likely to clot, or vein walls being in a damaged condition.

DVT most frequently, albeit not exclusively, develops in the veins of the lower leg. Of particular concern are the deep veins in the lower legs as well as the superficial veins in the lower legs (great and lesser saphenous veins). DVT can also develop in the thigh, and even in the pelvis or arm regions, but the occurrence of DVT in these areas are substantially less common.

Many solutions have been proposed to reduce the risk of DVT in persons subjected to limited mobility. A common preventative measure is to take medication in the form of anti-coagulants that reduces the tendency of blood to clot. However, these medications may result in the risk of excessive bleeding should a person be injured, due to the very purpose why the medication was administered. A further solution is to ensure that a person gets sufficient exercise so as to facilitate proper circulation via the natural pumping action induced by flexing and relaxing of the muscles. It will however be appreciated that this is not always feasible, as the very reason for low mobility may be the inability to stand up, or may be the result of being confined to a small space such as when travelling by aeroplane. In certain situations a person may at most be able to do foot exercises such as rotating the ankle and wiggling the toes, which will assist to prevent blood pooling in the feet. However, these marginal exercises are by no means sufficient to result in proper blood circulation.

Various systems have been proposed for overcoming the shortcomings due to the inability to properly exercise the leg muscles. Most of these systems are aimed at mechanically inducing and/or improving blood circulation. One such system is the use of compression stockings, which comprises socks that are tighter at the foot than higher up the leg so that there is a pressure gradient from the foot to the knee.

Although this system does aid blood circulation, it will be appreciated that there is no active muscle flexing and relaxing, and the effect is thus limited.

A still further preventative measure may be to utilise devices that pressurises the feet by means of inflatable chambers located inside a sock-like device. These devices may be limited to only covering a foot, but may also be configured to extend up to the knee. In addition such devices may include a plurality of inflatable chambers that may be sequentially inflated and deflated so as to achieve a proper pumping action.

Typical examples of such devices are described in United States Patents 4 624 244, 4-841 956-and-5 443 440. These type of devices substantially enhances blood circulation, but have the common disadvantage of requiring an extensive pressure supply and control system, thus making the systems heavy and bulky and also rendering it unsuitable for use in situations where the user is not in the vicinity of a suitable power source.

OBJECT OF THE INVENTION It is accordingly an object of this invention to provide an alternative device for reducing the risk of the developing of deep vein thrombosis that will, at least partially, alleviate the disadvantages as mentioned hereinbefore.

SUMMARY OF THE INVENTION According to the invention there is provided a device, suitable for reducing the risk of developing deep vein thrombosis in the human leg, the device comprising: a first engagement member, suitable for in use engaging a thigh of a human user of the device; a second engagement member, suitable to be engaged by a corresponding foot of the user when in use; the engagement members being resiliently connectable to one another; and being resiliently displaceable away from one another when a parting force is imparted on the connected engagement members; and an abutment member for abutting a calf of the user when in use; the abutment member being located between the first engagement member and the second engagement-member ; and- the abutment member in use being displaceable relative to one of the engagement members, and substantially stationary relative to another of the engagement members thereby to be displaced relative to the calf when the engagement members are displaced relative to one another.

The abutment member in use may be displaceable relative to the first engagement member, and substantially stationary relative to the second engagement member.

There is further provided for the first engagement member and a first end of the abutment member to be connected by way of an elastic connecting means, and for the second engagement member and an opposing end of the abutment member to be connected by way of an inelastic connecting means.

The elastic connecting means may be in the form of an elongate rubber band, and the inelastic connecting means may be in the form of a cord made of inelastic material.

Alternatively there is provided for the abutment member to be connected to an inelastic connecting means extending from the second engagement beyond the abutment member towards the first engagement member.

A further feature of the invention provides for the first engagement member to comprise at least two primary connecting members being inter-connectable so as to form a loop suitable for engaging the thigh.

The primary connecting members may be adjustably connectable relative to one another so as to adjust the size of the loop, and thus the distance between the first engagement member and the abutment member.

There is further provided for the first engagement member to include secondary connecting members extending from the primary connecting members, the secondary connecting members being adjustably connectable to one another so as to form an intermediate link between the primary connecting members, in so doing enabling the first engagement member to completely encircle a human thigh.

The first engagement member may further include a liner disposed towards an inner surface of the first engagement member, the liner being configured to be interposed between the connecting members and the thigh when in use.

The liner may include at least one gap toward an operatively upper part of the first engagement member.

There is provided for the liner to be made from foam rubber or other forms of padding. A still further feature of the invention provides for the second engagement member to comprise a ring-like structure made from at least partially tubular, flexible material.

An aperture formed by the ring-like structure may define a foothold for receiving a human foot.

The ring-like structure may be diametrically adjustable for snugly receiving feet of different sizes.

The second engagement member may also include a rigid support member being encapsulated in a remote part of the ring-like structure, with the inelastic connecting means being securable to ends of the rigid support member.

The second engagement member may further include a foot-retaining member for retaining a foot in the ring-like structure.

The foot-retaining member may be in the form of a pliable sheet extending between opposing sides of the ring-like structure. A yet further feature of the invention provides for the abutment member to comprise a pliable sheet extending between two spaced apart side supports.

The side supports may be substantially rigid so as to prevent the pliable sheet from folding when the abutment member is displaced relative to a calf of a user.

In yet a further embodiment there is provided for the abutment member to comprise a plurality of spaced apart elongate sections extending between opposing side supports.

The abutment member according to this embodiment may include rollers mounted on the elongate sections, the rollers being adapted to rotate about the elongate sections when the abutment member is displaced relative to the calf.

In a further embodiment the abutment member may be substantially rigid and semi- cylindrical so as to approximate the shape of a human calf. The abutment member may in addition be at least partially conical so as to more accurately approximate the shape of a human calf.

At least one edge of the abutment member may be outwardly flared so as to prevent the edge from biting into the calf when the abutment member is displaced relative to the calf. Preferably both edges that are orientated transverse to the direction of displacement of the abutment member will be outwardly flared.

The abutment member may also include a pliable bladder located on an inner surface thereof.

The bladder may comprise a pocket filled with a yieldable medium such as silicon gel, a lubrication fluid or air.

According to a further aspect of the invention there is provided a method for reducing the risk of developing deep vein thrombosis in the lower leg including the steps of: connecting the device according to any of the preceding claims to the leg of a user; extending the lower leg until a lower leg is at an obtuse angle relative to an upper leg ; and oscillating a foot engaging the device between a relaxed position, wherein the foot is substantially perpendicular to the lower leg, and a flexed position, wherein the foot is at an obtuse angle relative to the lower leg.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention are described by way of non-limiting examples, and with reference to the accompanying drawings in which: Figure 1 shows a first embodiment of a device for preventing deep vein thrombosis in accordance with the invention; Figure 2 shows a second embodiment of the device of figure 1; Figure 3 shows a third embodiment of the device of figure 1; Figure 4 shows a fourth embodiment of the device of figure 1; Figure 5 is a perspective view of a calf abutment member in accordance with the invention; Figure 6 is a perspective view of a foot support member in accordance with the invention; Figure 7 is a cross-sectional front view of the foot support member of figure 6, with the foot support member in a relaxed position; Figure 8 shows the foot support member of figure 7 in the contracted position; and Figure 9 shows the device of figure 1 in use on a human leg.

DETAIL DESCRIPTION OF THE INVENTION With reference to the drawings, in which like numerals indicate like features, a device for use in preventing deep vein thrombosis is generally indicated by reference numeral 10. The device 10 includes a first engagement member 12, which is suitable adapted to engage a thigh of a human leg, an abutment member 30 for abutting a calf of the leg, and a second engagement member 40 suitable for receiving a foot of a user. Various embodiments of the first engagement member 12, abutment member 30 and second engagement member 40 are described in more detail hereinbelow. It will be appreciated that any combination of these components can be combined in order to obtain any suitable arrangement.

The first engagement member 12 may comprise various configurations, as is for example depicted in figures 1,2 and 3. The first engaging member 12 typically comprises a pair of elongate primary connection members 14, which may be in the form of elastic chords as is shown in figure 1, or substantially rigid flat strips as shown in figures 2 and 3. A connecting mechanism 16 is used to adjustably connect the pair of primary connection members 14. The connection members 14 can thus be adjusted so as to fit the thigh of a particular user. The connection members 14 form a loop 17 that can be fitted around the upper part of the thigh of a user of the device. The first engaging member 12 as shown in figure 1 may also comprise two or more pairs of elongate primary connection members 14 being disposed substantially parallel relative to one another.

The first engagement means 12, as shown in figures 2 and 3, also include an upper liner 18 made of a soft, resilient material such as foam rubber, which in use is sandwiched between the connecting members 14 and the thigh of the user, so as to distribute the forces imparted in use on the leg of the user. Distribution of such forces serves to prevent pain due to the connecting members biting into the leg, and also to prevent excessive forces being exerted on the great saphenous vein.

In the embodiment shown in figure 3, the first engagement member 12 includes a pair of secondary connecting members 20, which is again adjustably connectable by means of a connecting mechanism 21. In this arrangement the first engagement member completely encircles the upper leg of the user so as to result in a more secure connection. A lower liner 22 is interposed between the leg and the secondary connecting members 20 for the reason as set out before. A gap 23 is left between the upper liner 18 and the lower liner 22 so as to prevent excessive forces being exerted on the great saphenous vein.

The abutment member is generally indicated by reference numeral 30, and three non-exhaustive embodiments of the abutment member are shown in figures 1,2 and 4 respectively. The abutment member as shown in figure 1 comprises a pliable sheet 39 extending between two opposing side supports 38. The pliable sheet 39 may be made of substantially inelastic material such as cotton, denim, leather or a thin sheet of polymeric material, but may alternatively be made from elastic material such as rubber or stretchable denim. A pliable bladder 33 may be located on an inner surface of the abutment member for assisting in reducing the friction of the abutment member relative to the calf of the user. The bladder 33 may for instance be in the form of a pocket filled with silicone gel, a lubricating fluid or air, and may be interposed between two layers of material making up the pliable sheet 39 of the abutment member 30. It will however be appreciated that such bladder 33 is by no means essential, and that the device 10 can be used without it.

The abutment member as shown in figure 2 comprises a semi-cylindrical open sleeve 31 which is at least partially conical in order better to match the profile of the user's calf. Upper and lower edges 32 of the abutment member 30 are outwardly flared so as to prevent the edges of the abutment member to bite into the calf of a user when it is displaced relative to the calf. A pliable bladder 33 may again be located on an inner surface 37 of the abutment member 30. In this embodiment the abutment member may be connected to the first 12 and second 40 engagement members in a plurality of ways. In a first method two pairs of inelastic connecting means may extend from opposing sides of the abutment member 30, and may for instance be connected to receiving apertures provided on the abutment member. This method of attachment is shown in figure 1. A further option, as shown in figure 5, may be to provide hook formations 60 on the abutment members. These hook formations 60 are suitably dimensioned to engage a rubber sleeve 61 that is located on the inelastic connecting means 26. The connection between the hook formations 60, sleeve 61 and inelastic connecting means 26 are sufficiently tight to prevent the abutment member 30 from being displaced relative to the second engagement member 40 when in use. However, it is possible to move the abutment member 30 by hand so as to adjust the distance between the abutment member 30 and second engagement member 40 if required. In addition, this configuration provides for easy replacement of the abutment member 30 with an abutment member of smaller or larger size so as to accommodate different calf sizes.

A further embodiment of the abutment member 30 is shown in figure 4. In this case the abutment member comprises a plurality of spaced apart elongate sections 35 extending between opposing side supports 38 of the abutment member. The elongate sections 35 shown in the particular embodiment are in the form of inelastic strings, but it will be appreciated that elongate rods, or partially elastic chord may also be used. A plurality of rollers 36 are mounted on the elongate sections 35, and are adapted to rotate about the elongate sections 35 when the abutment member 30 is displaced relative to the calf of a user. The rollers 36 depicted in figure 4 is of a spherical configuration, but any shape that would allow easy rotation will suffice. The rollers may for instance be oval or cylindrical.

The upper end of the abutment member 30 is connected to the first engagement member 12 by means of elongate, resilient connection means 25 which may for instance be in the form of rubber bands. The resilient connection means allow the abutment member 30 to be resiliently displaceable relative to the first engagement member 12. A lower end of the abutment member 30 is connected to the second engagement member 40 by means of elongate, inelastic connection means 26 which may for instance be in the form of an inelastic string or chord. The rigid and inelastic connection means causes the abutment member 30 to be stationary relative to the first engagement member 12.

The second engagement member 40 is described in more detail with reference to figure 6 to 8. One embodiment of the second engagement member 40 typically comprises a ring-like structure 41 or stirrup, which is at least partially tubular so as to define a passage 43 for receiving the inelastic connection means 26 therein. A rigid foot support member 42, which may for instance be in the form of a flat elastomeric strip or a substantially rigid rubber rod, is located inside the passage 43 in the ring- like structure 41. The rigid foot support member 42 is shorter than the width of the foot of a user, and ends of the foot support member are connected to ends of the inelastic connection means 26. When a force is exerted on the inelastic connection means 26, the ring-like structure 41 is deformed in the direction indicated by arrow A in figure 8. This causes a foot (not shown) of a user to be gripped by the contracted ring-like structure 41 so as to prevent the foot from moving relative to the second engagement member 40 or stirrup. The second engagement member 40 or stirrup may also include a foot-retaining member 44 that abuts the front part of a foot when in use, so as to prevent the foot from protruding too far through the ring-like structure 41. The foot-retaining member is typically in the form of a pliable sheet extending between opposing sides of the ring-like structure 41. The foot-retaining member 44 may include an aperture 45 for receiving the front end of the foot, and may alternatively be dish-shaped so as to approximate the profile of the front end of the foot. The circumference of the ring-like structure 41 is furthermore adjustable in order to accommodate feet of different sizes.

The use of the device 10 is described with reference to figure 9 in which a human leg 53 is shown to include a thigh 50, calf 51 and foot 52. A purely schematic representation of the device 10 as described hereinbefore is mounted on the leg 53 so that the first engagement member 12 engages the thigh 50, and the foot engages the second engagement member 40 or stirrup. The foot is kept in position by abutting the foot retaining cover 44 whilst simultaneously being gripped by the contracted ring-like structure 41 as described hereinbefore. The leg is now slightly extended to form an angle of approximately 135 degrees, and a slight force is exerted on the resilient connecting means 25.

The forces exerted on the device 10 are essentially in the directions as indicated by arrows B and C. Due to the orientation of the leg the first engagement member 12, abutment member 30 and second engagement member 40 form an arc indicated by broken line D. The forces B and C are applied to the ends of the arc D, and thus induce a resultant force E on the abutment member that forces the abutment member into contact with the calf 51.

Once the device 10 has been installed as per figure 9, the user pushes down with his or her foot 52 against the resilience provided by the elastic connecting means 25, as is indicated by arrow F. The large muscles in the calf, being the soleus and gastronemius muscles, are used to effect this foot movement, and repetitive flexing and relaxing of these muscles result in increased arterial blood flow. As the foot move back towards a relaxed position, the abutment member is displaced upwardly relative to the calf, and imparts a frictional and normal force on the calf due to resultant force E acting on the abutment member. The net result is that a massaging action is applied to the calf, and more particularly to the two large superficial veins, being the greater and lesser saphenous veins, so as to stimulate the venous outflow of the leg. It will be appreciated that the effect of repetitive flexing and relaxing of the soleus and gastronemius muscles, combined with the massaging action due to the abutment member, will result in at least improving and ideally maintaining proper blood circulation in the leg, and more particularly the lower leg.

It will be appreciated that this invention will solve or at least alleviate the problems associated with the prior art in that the device 10 is compact, does not need any external support or utilities, and still succeeds in at least improving blood circulation.

It will be further appreciated that the above are only some embodiments of the invention, and that many variations are possible without departing from the spirit and scope of the invention.