WO2006136024A1

WO2006136024A1 - Cast venting devices made of two flexible layers

Info

Publication number: WO2006136024A1
Application number: PCT/CA2006/001032
Authority: WO
Inventors: Alessandro Barberio
Original assignee: Alessandro Barberio
Priority date: 2005-06-23
Filing date: 2006-06-22
Publication date: 2006-12-28

Abstract

Venting device for surgical cast or brace comprises two elongate strips of flexible material with an inner one of the strips being porous. The two strips are spaced apart from each other and extend parallel to each other. On an inner face of the outer strip is an array of protrusions made by a thermoforming process and acting as spacers between the two strips. Preferably the two strips are connected to each other by a series of spaced-apart, flattened loops. The loops extend around the outer strip and are attached to the inner strip. They allow relative movement between the two strips in the longitudinal direction. The venting device can be wrapped in a spiral manner around a body part. Venting devices of this type can be used in combination with an elicoidal net to which a number of these devices can be attached.

Description

CAST VENTING DEVICES MADE OF TWO FLEXIBLE LAYERS

This invention relates to venting devices for surgical casts and medical devices such as braces and splints, and in particular, to devices for circulating air under a rigid cast, brace, or splint that may be applied, for example, to permit healing of a broken bone.

A variety of devices for venting devices for surgical casts have been proposed in the past but generally speaking these devices have not met with much commercial success at the present time. Some of these devices have tubes which form air passageways to permit air circulation between the rigid cast and the patient's skin. One such venting device is taught in U.S. Patent No. 4,898,160 which issued February 6, 1990 to Alliance Group Inc.

Canadian Patent No. 2,254,492 which issued December 9, 2003 describes a surgical cast venting device comprising an elongate strip of porous fabric material and a number of relatively short, elongate plastic tubing members distributed over and attached to the elongate strip on one side thereof. The tubing members each extend substantially parallel to this one side and are open ended. The elongate strip is adapted for winding around part of a human body prior to application of a surgical cast. Preferably the tubing members each have holes distributed along their respective lengths so as to permit the passage of air in and out of these members.

In published U.S. Patent Application No. 10/436,566 filed May 13, 2003, there are disclosed a variety of venting devices for a surgical cast or brace. One of these devices having a length and a width comprises two elongate strips of flexible material, with the material of the inner strip being porous. The two strips are spaced apart from each other by means of flexible spacer members, which also connect the two strips together. The spacer members form air passageways between one another so that air is free is pass along the passageways so as to permit air circulation. A moisture-absorbent porous fabric layer extends in a longitudinal direction along an outer side of the inner strip and covers this outer side. Preferably the inner strip of material is made of ethyl vinyl acetate (EVA). The descrϊption and drawings of this pending U.S. application are incorporated herein by reference.

Disclosed herein are several improved forms of venting devices for use with a surgical cast, brace, splint or other orthopedic device. According to one embodiment of the present invention, a venting device for use with a surgical cast, brace, or splint includes elongate, inner and outer strips of flexible material, the inner strip being porous and spaced apart from the outer strip. An array of protrusions is provided on and distributed over an inside surface of one of the strips and projects towards and engages an inside surface of the other of the strips. The protrusions act as spacers between the inner and outer strips and maintain the outer strip in a substantially parallel relationship to the inner strip when these two strips are arranged in a flat condition. There is also a series of spaced-apart loops connecting together the inner and outer strips, each loop being fixedly attached to respective one of the strips and extending around the strip to which the respective loop is not fixedly attached. In this way, the inner and outer strips are able to move longitudinally relative to one another when the venting device is being applied to a human or animal body part for use under the cast, brace or splint.

According to a first preferred form of this venting device, the array of protrusions act as spacer members between the two strips and form or create a gap between the two layers, wherein air is normally free to pass along and circulate both lengthwise and widthwise. The loops are preferably flattened and made of a suitable plastic. The preferred loops extend around the outer layer or strip and they are connected to the inner layer. Some longitudinal movement of the outer layer relative to the inner layer when the venting device is being applied to or wrapped around a patient's limb permits a better fit of the venting device around or on the limb prior to application of the cast material.

According to another embodiment of the invention disclosed herein, a venting apparatus for use with a surgical cast, brace or splint includes a porous, flexible tube having at least some elasticity, having two opposite ends which are open and has inner and outer surfaces. A plurality of strip-like venting devices are attached to the inner surface of the flexible tube and are arranged to form an internal structure having a tubular shape with two opposite open ends. The venting devices are arranged in a substantially side-by-side manner and each venting device includes elongate inner and outer strips of flexible material. The inner strip is porous and spaced apart from the outer strip and spacers are distributed over the inner surfaces of the strips, these inner surfaces facing each other, so as to maintain a substantially uniform space between the inner and outer strips of each venting device. Each spacer is connected to a respective one of the strips. A series of longitudinally spaced loops connect together the inner and outer strips and each loop is fixedly connected to a respective one of the respective strips and extends around the other respective strip.

The tube is preferably an elicoidal tube or net device in order to provide a tubular venting apparatus that can be slipped over a patient's limb or body part and then adjusted in size to fit snuggly around the body part before the cast material is applied around the exterior thereof.

According to a further aspect of this disclosure, a venting device can be provided by using two separate elongate strips of flexible material which are wrapped in spiral fashion around the patient's limb or body part. At least the inner strip of this material is porous while the outer strip of material is provided with an array of bumps or protrusions on one side thereof, which are made by thermoforming and which act as spacers when this strip is wrapped around the exterior of the other strip of flexible material. These two strips of material are wrapped in an opposite spiral manner around the limb or body part so that the outer layer of material crosses over the inner layer of material at a relatively large angle thereto, for example, 45 degrees of more.

According to a further embodiment of the present invention, a venting device for use with a surgical cast, brace or splint, includes two inner sections made of porous, thin flexible material, the inner sections each being formed with two opposite edges. These inner sections in use are arranged to extend around a body part of a human or animal in a close fitting manner with two opposite edges of one inner section meeting - A - respectively with the two opposite edges of the other inner section. There are also two preformed outer sections each formed with two opposite edges and each having a respective inner section receiving cavity between the opposite edges. The outer sections in use are arranged to extend around the two inner sections after the latter have been arranged on the body part with the two opposite edges of one outer section meeting respectively the two opposite edges of the other outer section. Spacers are arranged on at least one of the two inner and two outer sections and are distributed over inner surfaces thereof. These inner surfaces during use of the venting device face the other of the two inner sections and two outer sections. During use of this venting device on the body part, an air gap is provided between each inner section and its respective adjacent outer section.

According to one particular embodiment of this venting device, the preformed sections have been thermoformed to fit snuggly around a person's limb or body part to which a cast is to be applied. The two inner sections can comprise two thermoformed parts made of a perforated material such as EVA. The two outer sections can be two thermoformed parts of flexible material which, when placed together around the body part, form an outer layer that extends completely around the body part. These outer sections or parts can each be formed with an array of protrusions on their inner surfaces, and these act as the spacers between the inner and outer sections.

Further features and advantages become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate various preferred embodiments.

BRIEF DESCRIPTION QF THE DRAWINGS:

Figure 1 is an isometric view of a first embodiment of venting device constructed in accordance with the invention; Figure 2 is an isometric detail view showing an inner flexible layer of the venting device with a loop attached thereto;

Figure 3 is an isometric detail view similar to Figure 2 but showing an outer flexible layer mounted over the inner layer and held in place by the loop; Figure 4 is an isometric view of the outer layer of the venting device, this view showing an inner face thereof with protrusions formed thereof;

Figure 5 is an isometric view similar to Figure 4 showing an alternate form of outer layer wherein the longitudinal edges are serrated;

Figure 6 is an isometric view of an alternate form of the inner layer of the venting device, this inner layer having serrated edges similar to the outer layer of Figure 5;

Figure 7 is a cross sectional detail along a plane perpendicular to the patient's skin surface and showing a venting device according to the present invention positioned between the skin surface and a rigid cast, only a small portion of which is shown;

Figure 8 is an isometric view of another embodiment of the venting device of the invention, this view showing a separated loop connector at the right end of the device for ease of illustration;

Figure 9 is an isometric view of a flexible tube made of a net material which can be used in constructing a further embodiment of a venting device;

Figure 10 is an isometric view of a flexible tube constructed from a number of the venting devices of Figure 1 arranged side-by-side in a spiral manner, this flexible tube being insertable into the tubular net of Figure 9;

Figure 11 is an isometric view of a venting device constructed with the tubular devices of Figures 9 and 10, with the flexible tube of Figure 10 being inserted inside the tubular net; Figure 12 is a perspective view illustrating a venting device of the type shown in Figure 11 extending around a patient's elbow and extending over the wrist region;

Figure 13 is a side elevation illustrating a venting device of the type shown in Figure 11 mounted on a person's leg and located above the person's ankle;

Figure 14 is an isometric schematic view illustrating an elongate venting device constructed in the manner of Figure 1 wrapped in a spiral manner around a patient's limb; Figure 15 is a schematic side view illustrating how a single, elongate, porous strip can be wrapped in a spiral fashion around a patient's limb;

Figure 16 is a schematic illustration similar to Figure 15 but showing an outer layer of a venting device wrapped in an opposite spiral around the patient's limb (compared to the spiral wrap of Figure 15);

Figure 17 is a schematic side view showing the combination of the two layers applied to a patient's limb with the inner layer of Figure 15 shown mostly in dashed lines; Figure 18 is an exploded perspective view illustrating another embodiment of a venting device of the invention, this venting device being constructed with thermoformed, inner and outer sections; and

Figure 19 is a front view of the venting device of Figure 18 mounted on a patient's foot and ankle. One preferred form of venting device 10 is shown in Figure 1 and is elongate with a length substantially longer than its width W. For many applications, the venting device is substantially longer than illustrated in Figure 1, so that it can be wrapped around a patient's limb or body part prior to the application of cast forming material. The device 10 includes an inner strip 12 and an outer strip 14 both made of a suitable flexible material. In one preferred from of the device, the material of both layers is elastomeric. The strip 12 is referred to as the inner strip for purposes of the present application, as this is the strip which is closest to the skin surface when the venting device is used on a patient. The strip 14 is the outer strip as it is located on the exterior of the inner strip and extends completely over the inner strip. At least the inner strip 12 is porous as can be seen from Figures 2 and 3. Preferably the inner strip is made porous by the distribution over its surface of numerous small holes 16 in a manner known per se. These holes are distributed evenly along the length and width of the strip and extend from the outside of the inner strip to the inner surface at 18. These holes act to allow air to flow from the interior of the venting device, that is the region of a gap 20, to the adjacent skin of the patient. The outer strip 14 is formed with an array of bumps or protrusions 22 which can have a flat distal end 24 as shown in Figure 4 or a rounded end as shown in Figure 7. Figure 4 illustrates how the bumps can be distributed over the length and width of the outer strip 14. It will be understood that the bumps 22 do not connect the inner and outer strips and in fact, some movement, particularly in the longitudinal direction of the venting device, is permitted between the two strips.

However the two strips 12 and 14 are connected to each other by means of a series of spaced-apart loops 26 which can have a generally rectangular shape as shown. The width X of each loop corresponds substantially to the width of the inner and outer strips. The height H of each loop, and in particular the internal height, corresponds substantially to the thickness of the outer strip, including the bumps or protrusions 22. In this way, the outer strip 14 is able to be inserted into and slides through the loops 26 in order to be connected to the inner strip 12. Preferably each loop 26 is made from suitable, thin plastic material. If desired, each loop 26 can be formed with extensions 28 and 30 on each side of a bottom section 32 of the loop. The extensions 28, 30 facilitate attachment of the loop to the inner strip 12. One or more attachment methods can be used to attach each of the loops 26. For example, each loop can be attached by means of well known double-sided tape (not shown) which tape can be applied to the bottom surface of the loop in the region of the extensions 28, 30. In addition to the adhesive tape or as an alternative form of attachment, one or more stitches 34 can be used to connect the bottom section 32 of the loop to the inner strip 12. Instead of stitches, it is also possible to use a stainless steel staple (not shown) which joins together the inner strip 12 and the bottom section 32 and which has its flat side at the inner surface 18 of the strip. If desired, or if necessary to prevent skin contact by the staple, the staple can be covered with suitable adhesive tape that is capable of adhering to the flexible material from which the inner strip 12 is made.

The width Y of each loop 26 can vary but in a preferred embodiment of the venting device, the width Y is about one-half inch. The loop should not be too wide in this direction because the more rigid plastic forming the loop generally does not bend when the underlying inner strip 12 is bent. The bumps or protrusions 22 can be readily formed on the flexible plastic outer strip 14 by a known thermoforming process. A preferred material for both the inner and outer strips is ethyl vinyl acetate (EVA) which is amenable to this thermoforming process. It should be appreciated that an advantage of the evenly distributed, well spaced bumps 22 as compared to the elongate spacer members disclosed in the aforementioned U.S. Patent Application No. 10/436,566 is that they allow the airflow in the gap 20 to flow both in the longitudinal direction of the venting device 10 and in the lateral direction. Moreover, because the airflow is able to move laterally, the air can flow from one winding of the venting device to an adjacent winding when the venting device has been wrapped in a spiral manner about a limb, as shown for example in figure 13. Furthermore, because the bumps 24 are integrally formed on the outer strip 14, it is not necessary to attach these bumps by use of adhesive or double-sided tape. Moreover, the bumps are securely held in their position, unlike spacer members held in place by double-sided adhesive tape, or by adhesive, both of which may be subject to failure during some applications of a venting device that uses adhesive for this purpose.

Figure 5 illustrates an alternate form of outer strip 40 which can be used instead of the outer strip 14 of Figure 4. The only difference in the construction of the outer strip 40 is the use of longitudinally extending serrated edges at 42 and 44 instead of straight edges. The outer strip 40 can be used in combination with the thin, flexible inner strip 46 illustrated in Figure 6. It will be understood that the inner strip 46 is substituted for the inner strip 12 used in the embodiment of Figure 1. The inner strip 46 also has serrated longitudinal edges at 48 and 50. An advantage achieved with the use of serrated longitudinal edges is that it permits adjacent edges of an elongate venting device that has been wrapped around a limb or body part (as illustrated in Figure 13) to lock together so that there is no relative movement between them or very little movement after the venting device has been put in place. This is turn can help to hold the wrapped venting device in its proper position, prior to and during application of the cast forming material.

Figure 7 illustrates the application of and use of the present venting device 10 on a patient. The skin surface is indicated at 52. A thick layer of cast material 54 is shown extending over the venting device 10, which, it will be understood, has been wrapped around the patient's body part, preferably in the spiral manner shown in Figure 14. The thermoformed bumps 22 formed on the outer strip 14 effectively function as spacer members, creating the gap 20 for aeration purposes. Air flowing through the gap 20 is able to reach the skin surface by means of the aforementioned small holes 16 distributed evenly over the inner layer 12. Also as illustrated in Figure 7, the inner layer 12 can be substantially thinner than the outer strip 14, even if one does not include the thickness of the bumps 22. Thus, the inner strip 12 is able to conform closely to the contours of the patient's skin. With reference now to Figure 14, this figure illustrates schematically how air circulates through a spirally wrapped venting device 10 constructed in accordance with the invention. The venting device has been applied to an elongate limb having a generally cylindrical exterior, this limb being indicated schematically at 60. Because the venting device 10 has been constructed using the bumps 22 to form the gap 20, there is an air gap 20 at both the upper end 62 of the wrapped venting device and at the bottom end 64. The gap 20 in each loop of the venting device is open to the similar gap 20 in the adjacent loop or loops. This permits an air stream or air flow indicated by the long arrows 66 to pass from one end of the coiled venting device to the other end. Although the illustrated arrows show this airflow passing from the bottom end to the upper end 62, the airflow could of course be in the opposite direction, or could in some cases be in both directions. The shorter arrows 68 that extend from the arrows 66 illustrate schematically how the air flow turns 90 degrees in the gap 20 to pass through the inner strip 12 to the skin of the limb or body part.

Thus, this venting device does provide good air circulation to most regions of the skin below the cast, which is not shown in Figure 14. If desired, a porous fabric layer, such as a layer of gauze, can be wrapped or otherwise placed over the skin prior to the wrapping of the venting device about the body part.

The width of the elongate strips forming the venting device for use in the manner shown in Figure 14 can vary, but in one preferred embodiment, these strips range between one and a half inches and three inches in width.

Another form of venting device 150 constructed in accordance with the invention is illustrated in Figure 8. This venting device 150 is similar in its construction to the venting device 10 of Figures 1 to 3 except for the differences described herein. The venting device 150 includes an inner strip 152 and an outer strip 154 both made of a suitable flexible material such as EVA. The inner strip 152 is porous with numerous small holes distributed over its surface similar to the holes 16 shown in Figure 2.

The two strips 152 and 154 are connected together by means of a series of spaced-apart loops 156, one of which is shown separately at the right end of the device 150 in Figure 8. Again the width of each loop corresponds substantially to the width of the inner and outer strips. However, the height H' of each of the strips in this embodiment corresponds substantially to the thickness of the complete venting device 150 including both the inner and outer strips. In this way, each loop 156 extends over the top of the outer strip 154 and extends across the bottom of the inner strip 152 where it can be attached to the inner strip. Again each loop 156 can be made from a suitable, thin plastic material or it can be made from a softer material such as suitable, thin foam material, the latter material being quite comfortable when applied to the user's skin. This foam or sponge material is flexible and elastomeric and easily bends with the contour of the user's skin. Each loop can be formed as a complete loop as shown or it can be formed from an elongate strip of material as is bent at several locations to form a flattened loop with the two ends of the strip meeting at the middle of the outer layer approximately at the location 160 indicated in Figure 8. The adjoining ends of the strip can be connected together at 160 by a suitable one-sided tape or by adhesive. If the loops 156 are made from sponge or foam material rather than non- porous plastic, then the loops themselves are porous and allow the passage of air where they extend between the user's skin and the inner strip 152. In one embodiment, the loops are made from thin, perforated Eva material. The strips can be pre-perforated with a number of small holes similar to the holes 16 of the inner strip illustrated in Figure 2. Each loop 156 can be secured to the inner strip 152 in the same manner that the loops 26 are secured except for being secured to the bottom of the inner strip and in particular, it is possible to secure the loops by means of double sided adhesive tape or by stitches.

Turning now to another form of venting device illustrated by Figures 9 to 11, this venting device 70 is similar in its construction to the venting apparatus described and illustrated in my pending U.S. Patent Application No. 10/436,566, the description and drawings of which are incorporated herein by reference. However, the venting device 70 incorporates a number of venting devices 10 constructed in the manner illustrated in Figures 1 to 3 or in the manner illustrated in Figure 8 and includes the use of the loops 26 on these devices. The venting device 70 includes a porous, flexible tube, 72, shown separately in Figure 9. This tube has at least some elasticity and is preferably in the form of a net structure wherein the tube has two opposite ends 72 and 76, which are open and inner and outer surfaces 78 and 80. This tube in one preferred embodiment comprises Surgilast (registered trade-mark) net which is a stretchable piece of fabric material having a significant amount of elasticity. As such, this material allows the venting device 70 to be slid over the desired body party i.e. a body part with a broken bone, which must be kept immobile by means of a cast. This tube can preferably be adjusted in its diameter by twisting its end sections in opposite directions about its central axis.

The venting device 70 includes a plurality of elongate venting devices 10 which are arranged in the form of an internal tube 82. The venting devices 10 are attached to the inner surface of the flexible tube 72 so that, as shown in Figure 11, the tube 82 is located within the tube 72 and the combination forms the venting device 70 of Figure 11. Each venting device 10 can be arranged in a spiral manner and can as shown extend from one open end of the tube 72 to the opposite open end. The venting devices 10 are arranged in a side-edge to side-edge manner relative to one another. The venting devices 10 can be attached to the tube 72 by means of adhesive, double-sided adhesive tape or stitching. In a preferred embodiment of the venting device 70, the internal diameter of the device is sized so as to fit reasonably close to the exterior of the body part on which the venting device is mounted. Because body parts differ in size, depending on such factors as the nature of the body part to be covered and the size of the person or animal requiring the cast, the venting apparatus can be provided in several different standard sizes. Thus the doctor or veterinarian can use the venting device 70 that is closest in size, i.e. internal diameter, to the width or diameter of the body party, and can select a venting device which is slightly larger in its internal diameter than the body part. The venting device can then be reduced in its diameter to fit the body part by twisting the tube 72 about its longitudinal axis.

Figure 12 illustrates use of one of the venting devices 70 on a person's elbow and forearm, the patient's arm being indicated at 85 and his hand at 86. If required, an opening can be formed at 88 to accommodate the patient's thumb. Because the venting device 70 is flexible and bendable, it is able to bend around a sufficiently large obtuse angle formed at the elbow as shown in Figure 12. Figure 13 illustrates the use of the venting device 70 on a person's leg 90. This is a straightforward use of the venting device 70 as illustrated leg 90 is relatively straight. It will be noted that the bottom end 92 of this venting device is located above the ankle 94 of the patient. Generally speaking, because of the sharp angle formed at the patient's ankle, a venting device constructed in the manner illustrated in Figure 11 is not used in this region, but an alternative venting device illustrated and described hereinafter (see Figure 18 and 19) can be used to cover the foot and ankle of a patient.

An alternate form of the present invention is illustrated in Figures 15 to 17. In these figures, a person or animal's limb is indicated schematically at 96. The limb is generally long and approximately cylindrical in shape and it will be appreciated that the region of the limb shown is to be enclosed and covered by a rigid cast. Prior to the application of the cast material, there is first wrapped around the limb an elongate strip of flexible material 98 which can be constructed in the same manner as the aforementioned inner strip 12 of the first embodiment. The preferred material from which this strip is made is EVA and it is covered with numerous perforations indicated at 100. The strip is wrapped in a spiral manner as shown and it can be wrapped either clockwise or counterclockwise. The strip is wrapped so that the longitudinal edges 102 of adjacent loops are side-by-side and the loops do not overlap. By way of further explanation, the doctor or nurse can start wrapping at the top at point A and then wrap in a spiral fashion to a bottom point B. The next step in the formation of this venting device is the wrapping of an outer layer 104 about the same limb section. This outer layer is preferably constructed in the same manner as the outer strip 14 of the embodiment of Figure 1 with its inner surface covered by numerous spaced-apart bumps 22. It will be understood that this outer layer 104 is wrapped around the inner layer shown in Figure 15. In a preferred embodiment, this outer layer is also made of EVA material and the bumps thereon are formed by a thermoforming process. An important aspect of this venting device is that the outer layer 104 is wrapped around the limb in the opposite direction to the spiral wrap of the inner layer 98. Again, the doctor or nurse can start wrapping the outer layer at A' and can continue wrapping in a spiral manner to the bottom end location indicated at B'. By wrapping the two layers in this manner so that the outer layer crosses the inner layer at a substantial angle, a more thorough wrapping of the body part is provided and the end result is the venting device illustrated generally at 106 in Figure 17 that has few if any gaps or slots between adjacent loops that form the venting device.

With this construction, there is no need for the aforementioned loops 26 since there is no need to keep the outer layer or strip directly over and aligned with the strip forming the inner layer. It will be understood that the cast material will normally only be placed over the section of the limb that is covered by both the inner layer 98 and the outer layer 104. After the cast material has been put in place and has hardened, any sections or portions of either the inner or outer layers that project beyond the end of the cast can be trimmed or cut away. Another form of venting device 110 is illustrated in Figures 18 and 19. The venting device 110 is particularly suitable for use around a body part having a sharp bend therein, for example the ankle and foot region. A patient's foot is indicated at 112 and it will be understood that an ankle, which forms an approximate 90 degree bend is located at 114. The bottom portion of the person's leg is indicated at 116. The illustrated venting device 110 is preferably made with four separate sections, two inner sections 118 and 120 and two outer sections 122, 124. The two inner sections are generally similar in size and shape but are mirror images of each other. Similarly the two outer sections are similar in size and shape but are mirror images of each other. The two inner sections 118, 120 can be made of the same material (EVA) as the inner strip 12 of the first embodiment. The inner sections are flexible and are covered with numerous perforations 126. It will be understood that both the inner and outer sections are carefully cut and formed so that they will completely enclose and cover the body part or body section to be covered by the rigid cast. Both the inner and outer sections can be thermoformed using a suitable mould to have the required shape to fit a particular person's limb or body party. As thermoforming is a well-known process in the plastic molding art, a further description of this process herein is deemed unnecessary. Nevertheless it will be appreciated that a mould of a person's body part can first be created and then the inner and outer sections can be thermoformed using this specifically designed mould. The two outer sections 122, 124 can be constructed of the same thermoformed material as the outer strip 14 of the first embodiment. Again the inner surface of each outer section 122, 124 is covered by a number of bumps or protrusions 22 and these bumps or protrusions created an air gap between the inner section and the adjacent outer section. Instead of the short cylindrical bumps shown in Figures 18 and 19, it is of course possible for the protrusions to take a variety of shapes including rectangular and elliptical and this applies to the other embodiments of the invention described above. In some cases, it may not be necessary to thermoform the shape of the inner sections 118, 120 as the material forming these inner sections is quite thin and therefore very flexible and easy to conform to the shape of the body party. However, the outer sections 122, 124 are generally thermoformed, particularly where these outer sections must extend around a substantial bend.

It will be appreciated that when each of the inner sections are brought together (as indicated by the arrows Z in Figure 18), the curved edges 130 will meet each other along their length, while the rear edges 132 will also meet each other along their length. The same applies to the curved edges 134 and 136 of the two outer sections. When the inner and outer sections are brought together in this manner, they will form a completely enclosing venting device 110 as illustrated in Figure 19.

An advantage of using thermoforming to form the inner and outer sections in the manner illustrated in Figures 18 and 19 is that it can reduce the amount of gluing required to attach various components of the venting device together. Creating a specially formed venting device using thermoforming also enables the venting device to fit snuggly and in a well fitting manner about the body part, even one which bends substantially. In addition to the foot region or ankle region, venting devices constructed using a thermoforming process can also be quite useful for application around a patient's elbow or around a person's wrist (where there is a substantial variation in the dimension of the section of the body between the wrist and the adjacent hand). Of course it is also possible to use venting devices constructed in the manner illustrated in Figures 18 and 19 on other body parts such as a whole arm or a whole leg, if desired.

It will be appreciated that various modifications and changes can be made to the described and illustrated embodiments of venting devices without departing from the spirit and scope of this invention. For example, in the elicoidal venting device 70 of Figure 11, the number of elongate venting device strips that will be used will vary depending upon the particular application and the size of the venting device 70, but typically four or so venting devices 10 are coiled around the inside of the net tube 72. When one is using simply wrapped venting devices 10 in the manner of Figure 14, the number of venting devices that are used will depend upon different factors including the width of the venting devices 10 and the length of the cast required by the patient.

Claims

CLAIMS:

1. A venting device for use with a surgical cast, brace, or splint, said device comprising: elongate inner and outer strips of flexible material, said inner strip being porous and spaced-apart from said outer strip; an array of protrusions provided on and distributed over an inside surface of one of said strips and projecting towards and engaging an inside surface of the other of said strips, said protrusions acting as spacers between said inner and outer strips and maintaining said outer strip in a substantially parallel relationship to said inner strip when these two strips are arranged in a flat condition; and a series of spaced-apart loops connecting together said inner and outer strips, each loop being fixedly attached to a respective one of said strips and extending around the strip to which the respective loop is not fixedly attached, wherein said inner and outer strips are able to move longitudinally relative to one another when said venting device is being applied to a human or animal body part for use under said cast, brace or splint.

2. A venting device according to claim 1 wherein said protrusions are integrally formed on said one strip by a thermoforming process.

3. A venting device according to claim 2 wherein said protrusions are formed on said outer strip and said loops are attached to said inner strip and extend around and over said outer strip.

4. A venting device according to any one of claims 1 to 3 wherein each strip has two longitudinally extending edges on opposite sides of the respective strip and said longitudinally extending edges are serrated so that when said venting device is wrapped in a spiral manner around said body part, adjacent edges of adjacent loops of the venting device lock together, thereby preventing relative longitudinal movement between these adjacent edges.

5. A venting device according to any one of claims 1 to 4 wherein each loop is generally rectangular, has a width corresponding substantially to the width of said inner and outer strips, and has an internal height corresponding substantially to the combined thickness of the strip around which the loop extends and said protrusions.

6. A venting device according to any one of claims 1 to 5 wherein each loop is made from thin plastics material and is attached to its respective one strip by means of adhesive material.

7. A venting device according to any one of claims 1 to 6 wherein said inner and outer strips are made of ethyl vinyl acetate material which is elastomeric.

8. A venting apparatus for use with a surgical cast, brace or splint, said device comprising : a porous, flexible tube having at least some elasticity, having two opposite ends which are open, and having inner and outer surfaces; and a plurality of strip-like venting devices attached to said inner surface of the flexible tube and arranged to form an internal structure having a tubular shape with two opposite open ends, said venting devices arranged in a substantially side-by-side manner, each venting device including elongate inner and outer strips of flexible material, said inner strip being porous and spaced-apart from said outer strip spacers distributed over inner surfaces of said strips, these inner surfaces facing each other, so as to maintain a substantially uniform space between the inner and outer strips of each venting device, each spacer being connected to a respective one of said strips; and a series of longitudinally spaced loops connecting together said inner and outer strips, each loop being fixedly attached to a respective one of said respective strips and extending around the other respective strip.

9. A venting apparatus according to claim 8 wherein said spacers are protrusions integrally formed on one of said inner and outer strips of each venting device by a thermoforming process.

10. A venting apparatus according to claim 9 wherein said protrusions are formed on said outer strip of each venting device and said loops are attached to the inner strip of each venting device and extend around and over their respective outer strip.

11. A venting apparatus according to any one of claims 8 to 10 wherein each loop is substantially rectangular when viewed in a lengthwise direction of the respective venting device and has a width corresponding to the width of its respective inner and outer strips.

12. A venting apparatus according to any one of claims 8 to 11 wherein each loop is made from a thin plastics material and is attached to its respective one strip by means of adhesive material.

13. A venting apparatus according to any one of claims 8 to 12 wherein said flexible tube is made of Surgilast™ net which is stretchable and has a substantial degree of elasticity and wherein the diameter of said venting apparatus is adjustable by twisting one end of said tube relative to the opposite end about a central axis of the tube.

14. A venting apparatus according to any one of claims 8 to 13 wherein the outer strip of each venting device is attached to said tube by adhesive bonding and both inner and outer strips of each venting device are made of ethyl vinyl acetate.

15. A venting device for use with a surgical cast, brace or splint, said device comprising: two inner sections made of porous, thin flexible material, said inner sections each being formed with two opposite edges, said inner sections in use being arranged to extend around a body part of a human or animal in a close fitting manner with the two opposite edges of one inner section meeting respectively the two opposite edges of the other inner section; two preformed outer sections each formed with two opposite edges and having a respective inner section receiving cavity between said opposite edges, said outer sections in use being arranged to extend around the two inner sections after the latter have been arranged on said body part with the two opposite edges of one outer section meeting respectively the two opposite edges of the other outer section; and spacers arranged on at least one of said two inner and two outer sections and distributed over inner surfaces thereof, these inner surfaces during use of the venting device facing the other of said two inner sections and two outer sections, wherein, during use of said venting device on said body part, an air gap is provided between each inner section and its respective adjacent outer section.

16. A venting device according to claim 15 wherein said two inner sections, said two outer sections and said spacers are formed by thermoforming using a mould apparatus having a mould cavity corresponding in shape and size to said body part.

17. A venting device according to claim 15 or 16 wherein said opposite edges of both inner sections and both outer sections are curved in order to accommodate a bend in said body part.

18. A venting device according to any one of claims 15 to 17 wherein said spacers are protrusions integrally formed on the inner surface of each outer section.

19. A venting device according to any one of claims 15 to 18 wherein said two inner sections are made of ethyl vinyl acetate and have numerous small perforations distributed over their respective surfaces for air ventilation.

20. A venting device according to claim 13 wherein each inner section is preformed so as to have a body part receiving cavity between the opposite edges of the inner section.