Title of Invention	"IMPROVED ORTHOPAEDIC ARTICLE FOR THE IMMOBLISATION OF THE LIMB OF A PATIENT AND PROCESS FOR THE MANUFACTURE THEREOF"
Abstract	The present invention relates to an improved orthopaedic article or device for the immoblisation of the limb of a patient and to a process for the manufacture of such an article. The improved article comprises an endless substrate made from fabric knitted on a crochet or raschel knitting machine or a needle loom from 100 to 500 denier yarn of natural or man-made fibres or blends thereof and has applied to the surface thereof a water-curable isocyanate prepolymer. The prepolymer consists of a balanced combination of an aromatic isocyanate and a polyol in a specific ratio by weight conforming to the percentage of the weight of the NCO group in the resultant prepolymer. The water curable prepolymer is one which is not adversely affected in tropical climates.

Title of Invention

"IMPROVED ORTHOPAEDIC ARTICLE FOR THE IMMOBLISATION OF THE LIMB OF A PATIENT AND PROCESS FOR THE MANUFACTURE THEREOF"

Abstract

The present invention relates to an improved orthopaedic article or device for the immoblisation of the limb of a patient and to a process for the manufacture of such an article. The improved article comprises an endless substrate made from fabric knitted on a crochet or raschel knitting machine or a needle loom from 100 to 500 denier yarn of natural or man-made fibres or blends thereof and has applied to the surface thereof a water-curable isocyanate prepolymer. The prepolymer consists of a balanced combination of an aromatic isocyanate and a polyol in a specific ratio by weight conforming to the percentage of the weight of the NCO group in the resultant prepolymer. The water curable prepolymer is one which is not adversely affected in tropical climates.

Full Text	The present invention relates to an improved orthopaedic article or device for the immoblisation of the limb of a patient. The best known example of such orthopaedic immobilisation devices is the plaster of paris bandage which has been known and employed in the art for years for the purpose of immoblising the limb of patient. In general, the prior art plaster of paris bandage comprises an endless strip of gauze or the like fabric which constitutes a substrate upon which a layer or coating of of plaster of paris is deposited. This provides a ready-to-use article capable of being employed simply dipping it in water and then wrapping it around the patient's limb to be immobilised to form what is known as a cast. Unfortunately, plaster of paris bandages suffer from a basic drawback arising out of the fact that plaster of paris possesses the characteristics of being extremely sensitive to water. Hence, the person wearing a cast made of plaster of paris has to be extremely careful at all times to protect it from water. This makes matters very difficult for the patient concerned since he or she cannot with impunity perform simple everyday acts which, in normal conditions would come naturally to them, such as having a bath or taking a shower. Secondly, prior art plaster of paris bandages suffered from the drawback of weight. Plaster casts made from plaster of paris bandages tended to be very heavy which made it extremely uncomfortable for the wearer over a protracted period of time. What is more, in addition to their weight, prior art orthopaedic immobilisation devices were in general not porous. Hence in the summer in warm climates, the perspiration generated by the user of such devices did not evaporate but remained trapped underneath the device on the surface of the skin of the wearer. Over a prolonged period, this frequently caused irritation and itchiness to occur. In view of the inherent drawback of water sensitivity of prior art orthopaedic immobilisation devices made from plaster of pan's, efforts continued to be made to improve these devices. One such improvement is described in and formed the • subject of Indian Patent No. 148709 of Johnson & Johnson. This Indian patent provided a water-resistant orthopaedic bandage comprising a hardenable plaster of paris composition including a reactive silicone polymer supported on a known flexible carrier wherein the plaster of paris content ranged from 100 to 600 grams per square yard of the carrier and the reactive silicone polymer ranged from 0.5 to 10 parts per hundred parts of plaster of paris. The Johnson & Johnson bandage was only slightly less heavy than hitherto known bandages. However, the major problem which it exhibited was that although the water resistance was better, the bandages had virtually no porosity. This fact nullified the advantage of having a slightly better water-resistant bandage because in the event that the cast got wet, the cast might dry on the outside but because the plaster was not porous, it remained damp on the inner side which was in contact with the wearer's skin. This made it very uncomfortable for the wearer. Other efforts to remove the drawbacks inherent in plaster of paris orthopaedic immobilisation devices were also made. These attempts were geared at the replacement of the plaster of paris component of the bandages by alternative substances which provided better water resistance. The results of these efforts are evidenced, inter alia, in Indian Patents Nos. 143546 and 147226 which made-use of synthetic chemical cements. The procedure involved the coating of one synthetic component on to a length of fabric such as gauze and adding the other component to the water in which the bandage to be employed on a patient had to be dipped. These bandages when made into plasters were fairly water-proof but the major drawback to them was that they took too long to set and were not porous enough to make the wearer comfortable. During the 1970's, a new type of orthopaedic immobilisation article appeared in the market. This comprised a bandage in which a fibreglass fabric substrate was coated with the reaction product of isocyanates and polyols. Regretably, these bandages did not find favour with orthopaedic surgeons who, accustomed as they were to using the prior art plaster of paris bandages, disliked the newer orthopaedic immobilisation articles which they found bulky, slow to set and tacky. In addition, the fact that these bandages incorporated a fibreglass fabric base, they were difficult to cut when it was time to have the plaster removed. In view of the reservations of many orthopaedic surgeons to bandages with a synthetic component coated on the fabric substrate, successive efforts were made to overcome the drawbacks to which the surgeons objected. These efforts did indeed overcome some of the drawbacks and the usage of such bandages grew but the latter were not universally accepted as meeting every orthopaedist's precise requirements. One such bandage which came out of these efforts forms the subject matter of prior Indian Patent No. 177417. This Indian patent provided an orthopaedic article comprising a fabric sheet and a water-curable isocyanate-functional prepolymer resin coated on to the fabric sheet, said pre-polymer resin having a stable dispersion of hydrophobic polymeric particles therein. Prior art bandages such as that of Indian Patent No. 177417 suffered a number of problems essentially because the fabric substrate employed therefor was made of fibreglass or a comparable material. Fibreglass is not a soft material. In fact, it is a rather rough one and so bandages where the substrate was fibreglass were very harsh on a patient's skin and therefore most uncomfortable for him. Moreover, because fibreglass does not adhere well to polyurethanes, it became the practice to abrade purposely the fibreglass in order to promote better adherence between the substrate and the coating thereon. Furthermore, fibreglass happens to be one of the heavest yarns, that is to say, it has a very high density in comparison to other materials. As a result, the overall weight of these prior art bandages went up. Added to that was the reduced ability of the resin to adhere to the fibreglass which meant that an increased amount of resin had to be applied to the substrate making the weight of the prior art bandages heavier and therefore more uncomfortable for a wearer. Fibreglass being a synthetic material is very difficult to cut. It was thus found that bandages such as those of Indian Patent No. 177417 which employed a fibreglass substrate could not be cut by hand saw as used to be the case of the older plaster of paris bandages. In order to remove a cast having a fibreglass substrate, it was necessary to cut it away using an oscillating plaster saw. In doing this an oscillating plaster saw generated a lot of fibreglass dust which was very harmful for the lungs if inhaled by either the patient or orthopaedic doctor. A still further drawback resided in the fact that after a fibreglass bandage is removed from a patient's limb, it cannot be burned in an incinerator along with other hospital waste as it is now mandatory to do. Other drawbacks of prior art bandages employing fibreglass as a substrate reside in the fact that the fabric was not woven in the required width but was woven and/or knitted on wide looms known as Raschel Machines in in widths of 1 meter or more and then slit to the required width of 7.5 cm to 12.5 cm. This caused the cut threads at the slit edges to protude out of the fabric and when coated with the polyurethane adhesive, these hardened into a number of sharp points which caused severe discomfort to any wearer of the bandage by irritating, abrading or puncturing his skin. Yet again, prior art bandages were made purposely using coarse counts of fibreglass yarn mostly of the order of 800 to 1200 denier in order to achieve better green strength and better cured strength. These coarse thick yarns made the bandages difficult to apply and wrap around the tapered or irregularly shaped body parts. Most of the more sophisticated prior art bandages were developed by and manufactured for use in advanced countries where the climate is temperate to downright cold. That being so, the aspect of storage stability in hot and/or humid climates of the tropics was never taken into account since it was never thought of. As a result, prior art bandages tend to evince very poor shelf life in tropical countries and in less than six months more than 50% of imported bandages become unusable in the tropics. Hence, some bandages come with the labelled instructions "To Be Kept In Refergrator At Or Below 25° C". The basic object of the present invention is to remove the shortcomings and deficiencies of the prior art and to provide an improved orthopaedic article for the immoblisation of the limb of a patient which has none of the disadvantages of the prior art. Specifically, it is the object of the present invention to provide an improved orthopaedic article for the immoblisation of the limb of a patient which is extremely user friendly, such user friendness being evinced in an article which is gentle on the skin of the user, light-weight and thus overall more comfortable and yet having increased strength over prior art bandages to provide adequate support and immobility to the limb to which it is applied. A further object of the invention resides in an orthopaedic article for the immoblisation of the limb of a patient which avoids the sharp edges and protruding fibres of prior art orthopaedic articles which made such prior art articles so uncomfortable for users thereof. A still more specific object of the invention is an improved orthopaedic article for the immoblisation of the limb of a patient which, by selection of an appropriate substrate and the application thereto of a coating of specially selected curable resinous material, provides the improved orthopaedic article. Yet another object of the invention is the provision of an improved orthopaedic article for the immoblisation of the limb of a patient which can be easily applied to and removed from the limb in question and which is particularly suitable for employment in hot and tropical climates without subjecting the wearer to problems of discomfort associated in the past with prior art orthopaedic articles. A further object of the invention is the provision of an improved orthopaedic article for the immoblisation of the limb of a patient which is storage stable and exhibits extended shelf life even in tropical climates. Towards achieving these objects, the applicant has conducted his research under two aspects, first in respect of the fabric forming the substrate in respect of such orthopaedic articles and secondly, from the point of view of the water-curable resinous coating applied to such substrate. The research conducted was directed to the provision of a substrate and a coating which were not only compatible with each other but which, in combination, also exhibited the qualities desired for such an improved orthopaedic article including an enhanced shelf life. In general, prior art orthopaedic bandages employed substrates made of fibreglass which, as stated earlier, is one of the heaviest yarns with very high density, all of which made it very unsuitable for an orthopaedic bandage and most uncomfortable for a user of an orthopaedic bandage made therefrom. Moreover, it was believed that the higher the denier of the fibreglass yarn, the better the performance which is why earlier patents for orthopaedic articles showed a preference for coarse denier fibreglass yarns. With such an established preference for coarse denier yarns, it would have been quite reasonable to expect the applicant to confine his investigations to such yarns. In fact, it reinforces the novelty of the present invention that the applicant decided to ignore and go beyond the accepted theory and to investigate the suitability of fabrics made from fine denier yarns other than fibreglass. Thus, as opposed to the prior art which employed 800 to 1200 denier fibreglass yarn, the applicant has discovered that by employing fabric made from 100 to 500 denier yarn for the substrate, a cast bandage not only lighter in weight but of remarkably soft texture can be produced which bandage surprisingly evinced better storage stability in hot and humid climates than fibreglass bandages. In this connection, it is preferred to employ fabric made from yarns which have a greater number of filaments for the same denier. For example, if a 300 denier yarn is selected, it is preferred to employ a 300/144 yarn to a 300/96 yarn or a 300/96 yarn to a 300/36 yarn. The reason for this is that the greater the number of filaments for a given final count of the yarn, the finer the individual filaments would be. This has been found to enhance the desired property of softness in the resultant substrate over substrates known in the prior art. The applicant has established that the fabric from which the substrate of the orthopaedic article of his invention is made may be prepared from yarns of any of a number of natural or man-made fibres. These include cotton, rayon, jute, hemp, sisal, flax, polyethylene terephthalate, polypropylene, nylon, polyurethane, P.O.Y., polyester, Elastane, rubber thread fibres, aramid fibres, carbon fibres or blends of any of these. For example, one such preferred blend comprises polyester yarn with Elastane yarn. Elastane is a polymeric elastic yarn made of a polyurethane elastomer and, therefore, evinces good compatibility with the resin used for coating the substrate. Where Elastane is used, it may be used either per se or covered by or intermingled ith other yarns to enable easier handling. For the reasons mentioned, it is preferred to use low denier Elastane in order to get less stretch. However, the yarn most preferred for preparation of the fabric from which the substrate of the applicant's orthopaedic article is made is fully drawn multifilament polyester yarn. In a still further preferred embodiment, the novel fabric consists of a single-width knitted polyester fabric having fast edges. This provides the advantage that when such fabric is made into the substrate which constitutes the orthopaedic article or bandage, the width of the fabric is equal to the width of the substrate or bandage thereby avoiding the need to cut the fabric to the desired width of the substrate. When a fabric knitted out of such novel yarn is made into a substrate for a casting bandage, the softness of the bandage is remarkably increased. In addition to the yarn content of the fabric forming the substrate of his improved orthopaedic article, the applicant has also investigated the actual weave of earlier substrates in which the spaces between the yarns comprising the fabric were sufficiently narrow to be entirely clogged by the resin when the latter was applied thereto. The applicant discovered that if the substrate were to be prepared from fabric knitted on crochet knitting machines, such substrate was found to have larger spaces within the weave thereof which did not get completely blocked when the resin was coated thereon. A substrate prepared from fabric produced in this manner was found to result in a casting bandage which was porous but nevertheless possessed more strength while it was drying and setting and comparable weight bearing capacity to prior art bandages. It was found that a similar porous effect could be obtained when the fabric of the substrate was prepared on a raschel knitting machine or employing a needle loom. Alternatively, it was possible to employ either a thicker fabric into which holes of an enlarged diameter were physically punched or even a net-like fabric. The second area of research by the applicant related to the water-curable resinous coating applied to such substrate. As an initial investigation, the applicant researched water-curable isocyanates employed for the article of prior Indian Patent No. 177417. It was found that that TDI based isocyanates are toxic and require careful storage at low temperatures. Accordingly, the study of such TDI based was abandoned and other non-TDI isocyanates were studied and taken up for trials. To that end, the applicant examined aliphatic and aromatic isocyanates. It was found that aliphatic isocyanates cured far too slowly which made it impractical to obtain the required properties for the provision of a polyurethane precursor for application to the proposed orthopaedic article. Furthermore, the handling characteristics of aliphatic isocyanates left much to be desired. This led the applicant to investigation of aromatic isocyanates. The applicant's research was conducted with the object of obtaining a water- curable polyurethane precursor which displayed increased stability at higher ambient temperatures such as those usually encountered in tropical climates and, therefore, possessed a longer shelf life than precursors of the prior art. These efforts by the applicant have resulted in a water-activated isocyanate prepolymer comprising a balanced combination of an aromatic isocyanate and a polyol in a specific ratio by weight conforming to the percentage of the weight of the NCO group in the resultant prepolymer, optionally in the presence of a catalyst therefor and one or'more initiators, accelerators and excipients. The novelty of the present invention resides in the provision of an improved orthopaedic article or device for the immoblisation of the limb of a patient which comprises a specially created fabric substrate upon which a water-activated isocyanate prepolymer comprising a balanced combination of an aromatic isocyanate and a polyol in a specific ratio by weight is applied. Such ratio will vary depending on the precise isocyanate and polyol employed but would generally be in the range of from 1 : 1 to 1.8 : 1. Accordingly, the present invention provides an improved orthopaedic article for the immoblisation of the limb of a patient which comprises an endless substrate made from fabric knitted on a crochet or raschel knitting machine or a needle loom from 100 to 500 denier yarn of natural or man-made fibres or blends thereof having applied to one surface thereof a water-curable isocyanate prepolymer comprising a balanced combination of an aromatic isocyanate and a polyol in a specific ratio by weight of from 1 : 1 to 1.8 : 1 corresponding to the desired percentage by weight of the NCO group in the prepolymer, said prepolymer optionally containing a predetermined amount of strengthening agents such as herein described. The natural or man-made fibres from which the 100 to 500 denier yarns are made include cotton, rayon, jute, hemp, sisal, flax, polyethylene terephthalate, polypropylene, nylon, polyurethane, polyester, rubber thread fibres, aramid fibres, carbon fibres or blends of any of these. A particularly preferred yarn blend comprises a blend of polyester and polyurethane yarn. However, the yarn most preferred for preparation of the fabric from which the substrate of the orthopaedic article is made is fully drawn fine denier multifilament polyester yarn. When knitted from such yarn, the substrate exhibits a remarkable degree of increased softness. According to a preferred embodiment, the fabric of said substrate comprises a single-width knitted polyester fabric having fast edges, the width of the knitted fabric being equal to the width of the substrate constituting the bandage. The present invention also provides a process for the manufacture of an improved orthopaedic article for the immoblisation of the limb of a patient which comprises applying a water-curable isocyanate prepolymer comprising a balanced combination of an aromatic isocyanate and a polyol in a specific ratio by weight of from 1 : 1 to 1.8 :1 corresponding to the desired percentage by weight of the NCO group in the prepolymer to one surface of an endless substrate fabric knitted on a crochet or raschel knitting machine or a needle loom from 100 to 500 denier yarn of natural or man-made fibres or blends thereof to form a coated substrate, wherein said prepolymer optionally contains a predetermined amount of strengthening agents such as herein described, and storing the coated substrate in a moisture-proof environment. Although it does not form part of the invention, the prepolymer applied to the substrate can be prepared by subjecting a mixture of an aromatic isocyanate and a polyol in the said specific ratio by weight to controlled heat to obtain the desired prepolymer having a predetermined percentage of the weight of the NCO group. By the appropriate selection of the aromatic isocyanate and polyol, the water curable polyurethane prepolymer is able to evince greater stability at higher ambient temperatures as are normally encountered in tropical climates. This provides a significant advantage when employing such prepolymer in the manufacture of the casting bandage of this invention. Suitable polyols are those found to provide greater stability at room temperature for the resultant precursor. These include the polyether and polyester polyols and it is preferred to use the medium and low molecular weight polyether polyols as these afford enhanced strength and stability to the coated substrate. Optionally, the reaction of the aromatic isocyanate and the polyol is effected in the presence of a surfactant and/or a catalyst for the reaction. Also present may be one or more conventional initiators, accelerators and/or excipients. The preferred initiator or accelerator used is benzoyl peroxide but it is used at a very low percentage. The strength of the casting bandage can be increased by adding to the prepolymer prior to application thereof to the substrate a predetermined amount of one or more strengthening agents such as herein described. Examples of such said strengthening agents are calcium carbonate, small fibres of polyester, nylon or polypropylene or other conventional strengthening agents. Examples of such fillers or bulking agents include hollow glass beads, hollow microspheres, gas-filled microspheres or other conventional strengthening agents. However, a significant feature of the casting bandage of the present invention is thai no such strengthening or bulking agents are normally required since the desired degree of strength is provided by the unique fabric employed for the substrate. The invention will be described in greater detail in the following Example.. EXAMPLE To 160 grams of aromatic socyanate in a reaction vessel there were added 100 grams of poly ether polyol. The ingredients were mixed together and mixture then subjected to controlled heating to a temperature in the range of 80 °C to 100°C. in the presence of Benzoyl Peroxide as catalyst until a prepolymer having a predetermined percentage of the weight of the NCO group was formed (eg 16%). To the thus formed precursor there were added 20grams hollow glass beads and 10 grams hollow microspheres as strengthening agents. The polyurethane precursor thus prepared was then removed form the reaction vessel, stored for a predetermined period of time and later, while still in fluid condition, coated on to a fabric substrate made of fully drawn 300 denier/ 96 filaments multifilament polyester yarn knitted on a crochet knitting machine of between 180 to 300 grams per meter square knitted in the required width of the bandage. The coated substrate comprising a casting bandage was thereafter rolled on a core, placed within a pouch and the pouch heat sealed. The heat sealed pouch containing the rolled bandage was placed within another pouch which was likewise heat sealed. The sealing was checked and the sealed pouches were labelled with the batch number, date of manufacture, expiry date, size, price and other labelling information as required. Optionally, several sealed pouches containing coated and rolled bandages can be packed further into an overall outer metal or plastic container or cardboard box. To determine the shelf life of the coated substrates, the latter were subjected to a procedure known as accelerated ageing. Selected pouches within which the coated substrates were heat sealed were maintained at varying temperatures as follows: a) Room Temperature ( 25° C. to 30 ° C.) b) Hot Temperature (50° C.) c) Accelerator Ageing Temperature (70° C.) The RH was also monitored and recorded. In the normal course of transit or during storage, the coated substrates are not likely to be subjected to temperatures as high as 70° C. However, by exposing them to such temperatures, it was possible to assess the viability of the coated substrates and to extrapolate the expected shelf life thereof at room temperature. For example, if the coated substrate did not deteriorate or cure for three weeks at 70° C. or three months at 50° C., it was possible to predict a shelf life of three years for the product if maintained at room temperature. After the accelerated ageing procedure was complete, the properties of the poly urethane precursor coated upon the substrate were tested. Essentially, this test was to ascertain the free NCO percentage remaining in the precursor and to determine whether the precursor was still in pasty or liquid form or had cured and therefore solidified as result of the heat. As part of an effort to ensure that the improved orthopaedic article or casting bandage of the present invention is preserved in optimum condition for the end user, the applicant has also devised a novel packaging enclosure for the polyurethane precursor coated substrates. In the past, coated bandages were sealed individually within stiff pouches or envelopes made of polyethylene having rather sharp edges and corners. As many as ten to twenty individually sealed pouches were then packed into a larger outer carton in very close proximity to one another. As a result, during transit or movement, the sharp corners of one individual pouch frequently punctured the envelopes or the pouches of adjacent to it. This would ruin the sealed condition of the punctured pouches and allowed the ingress of moisture thereinto leading to premature curing of the coated substrates which were rendered unusable thereafter. In this connection, it should be noted that the polyurethane precursor if maintained at 25 ° C. and 65% RH for a period of from 4 to 12 hours will cure within the pouch and no amount of effort will cause the rolled bandage to unroll. The situation is aggravated by the fact that polyethylene is permeable to moisture and has a much higher moisture vapour transmittal rate (MVTR) in comparison to other packaging material. Some efforts have been made to improve the packaging of polyurethane casting bandages but even these are not suitable keeping in view the nature of the product. Packaging for polyurethane casting bandages currently available comprise a single pouch of thick gauge aluminium foil laminated with polyester film on the outside and heat sealable film on the inside. The thick aluminium foil is brittle and tends to break or tear even under the least pressure permittng ingress of moisture. This causes the ready-to-set polyurethane precursor coated on the bandages to cure and make the bandages hard and useless. Towards overcoming the defects of earlier packaging of precursor-coated substrates, the applicant has created an improved packaging and this is described in greater detail with reference to the accompanying drawings in which: Figure 1 represents an isometric view, partly in section, of the single-pouch packing of prior art casting bandages; Figure 2 represents an isometric view, partly in section, of the improved multi-envelope packaging for polyurethane precursor-coated casting bandages of the present invention; Figure 3 represents an isometric view, partly in section, of a further embodiment of the improved multi-envelope packaging for polyurethane precursor-coated casting bandages of the present invention; Figure 4 represents a flowsheet illustrating the various stages in the preparation of the novel polyurethane precursor-coated casting bandages of the present invention from commencement to final packaging thereof; and Figure 5 illustrates a preferred design of weave of knitted fabric employed for the substrate of the novel polyurethane precursor-coated casting bandage of the present invention. The prior art packaging of Figure 1 clearly shows a coated casting bandage 10 sealed within an individual polyethylene envelope 12. Figure 2 of the drawings discloses an improved coated substrate 14 according to the present invention sealed within a first or inner moisture-proof pouch 16. This pouch is made of a multi-layered laminated heat sealable film comprising at least one layer of an elastomeric polymer such as LDPE, LLDPE, HOPE or other thermoplastic polymers laminated with one or more layers of metallised film, aluminium foil, paper or polyester film. Preferably, inner pouch 16 includes at least one layer of aluminium foil and should consist of a minimum of three laminated layers. Inner pouch 16 is located within an outer sealed pouch 18 which is likewise made of a flexible material which is virtually impermeable to water vapour and which is neither rigid nor brittle. As in the case of inner pouch 16, outer pouch 18 is made of a multi-layered laminated heat scalable film comprising at least three layers of metallised film, aluminium foil or paper located between other layers of polymeric film. Preferably, outer pouch 18 contains at least one layer of aluminium foil. As shown in Figure 2, outer pouch 18 is provided within a larger overall external packaging envelope 20. It will be observed that external packaging envelope 20 is large enough to make provision for a plurality of coated substrates 14 within their inner and outer pouches 16, 18. Figure 3 illustrates an alternative embodiment of the packaging shown in Figure 2 in which a coated substrate 14 located within its inner and outer pouches 16, 18 is provided within a container 24 of metal or plastics having an air-tight, moisture proof lid 22 fitted thereon. This may also be a corrugated carton. Preferably, the inner pouches 16 and the outer pouches 18 are packed under vacuum or flushed with dry air or nitrogen in order to increase further the shelf life of the coated substrates 14. These steps for ensuring enhanced shelf life can be carried out in any combination and in any order. The inner and outer pouches 16, 18 may also contain a desiccant bag filled with any suitable desiccant material for example silica gel, molecular sieves or calcium chloride. This desiccant will absorb any humidity permeating the pouch so that it does not reach the bandage and will increase the storage stability of the bandage. The improved packaging produced by the applicant is not restricted to the specific material described herein for manufacture of the pouches. Any equivalent material having the same properties could be substituted without affected adversely the invention in question. The flow chart of Figure 4 is pre-eminently clear in itself and requires no elucidation. Figure 5 illustrates by way of example a preferred design of weave of knitted fabric employed for the substrate of the novel polyurethane precursor-coated casting bandage of the present invention. However, it must be understood that any other comparable weave or knitted pattern could be employed with equal effect. For a practical application of the improved orthopaedic article of the present invention, the following description is provided by way of instructions. The patient is made to wear stockinette and then cotton wool or orthopaedic cast padding is wrapped on the part where cast is to be applied. Then the required amount of water is taken in a container and the outer pack of the bandage is opened. Then with gloved hands the outer and inner pouch of bandage is opened and bandage taken out. It is immediately dipped in water for 1 - 3 seconds & bandage squeezed lightly. Now the bandage is wrapped around the fractured limb without tightening and the desired shape is given while soft. It generally sets hard in 3 to 8 minutes of taking out of water but the preferred version sets in 4 to 6 minutes. The improved orthopaedic article of the present invention is a versatile product having multiple uses. It can be used by orthopaedic surgeons for short or long time immobilisation of a limb. It can also be used as a do it yourself (DIY) item for the repairs of broken of leaking pipelines such as water pipes without having to shut down the entire water flow line and as a repair and maintenance tool to mend broken articles. It can also act as strong reinforcing tape for example for broken hockey sticks and similar articles of household or industrial use whenever a proper reinforcement or adhesive is not immediately available. The polyurethane casting bandage of the present invention is endowed with long shelf life and a soft feel as an immobilising product. All these qualifications should change the image of orthopaedic plasters by presenting something which is more acceptable to a patient and is less likely to generate perspiration and irritation in the wearer. WE CLAIM: 1. An improved orthopaedic article for the immoblisation of the limb of a patient which comprises an endless substrate made from fabric knitted on a crochet or raschel knitting machine or a needle loom from 100 to 500 denier yarn of natural or man-made fibres or blends thereof having applied to one surface thereof a water-curable isocyanate prepolymer comprising a balanced combination of an aromatic isocyanate and a polyol in a specific ratio by weight of from 1 : 1 to 1.8 : 1 corresponding to the desired percentage by weight of the NCO group in the prepolymer, said prepolymer optionally containing a predetermined amount of strengthening agents such as herein described. 2. An improved orthopaedic article as claimed in claim 1 wherein said natural or man-made fibres include cotton, rayon, jute, hemp, sisal, flax, polyethylene terephthalate, polypropylene, nylon, polyurethane, polyester, rubber thread fibres, aramid fibres, carbon fibres or blends of any of these. 3. An improved orthopaedic article as claimed in claim 1 or 2 wherein blend of yarns comprises a blend of polyester and polyurethane yarn. 4. An improved orthopaedic article as claimed in any of claims 1 to 3 wherein the yarn from which the fabric forming the substrate is prepared is preferably polyester yarn. 5. An improved orthopaedic article as claimed in any of claims 1 to 4 wherein said strengthening agents are selected from one or more of calcium carbonate, small fibres of polyester, nylon or polypropylene or other conventional strengthening agents. 6. An improved orthopaedic article for the immoblisation of the limb of a patient substantially as herein described. 7. A process for the manufacture of an improved orthopaedic article for the immoblisation of the limb of a patient which comprises applying a water-curable isocyanate prepolymer comprising a balanced combination of an aromatic isocyanate and a polyol- in a specific ratio by weight of from 1 : 1 to 1.8 : 1 corresponding to the desired percentage by weight of the NCO group in the prepolymer to one surface of an endless substrate fabric knitted on a crochet or raschel knitting machine or a needle loom from 100 to 500 denier yarn of natural or man-made fibres or blends thereof to form a coated substrate, wherein said prepolymer optionally contains a predetermined amount of strengthening agents such as herein described, and storing the coated substrate in a moisture-proof environment. 8. A process as claimed in claim 7 wherein said polyol is a polyether polyol. 9. A process as claimed in claim 7 or 8 wherein said strengthening agents are selected from one or more of calcium carbonate, small fibres of polyester, nylon or polypropylene or other conventional strengthening agents. 10. A process for the manufacture of an improved orthopaedic article for the immoblisation of the limb of a patient substantially as herein described.

Full Text

The present invention relates to an improved orthopaedic article or device for the immoblisation of the limb of a patient.
The best known example of such orthopaedic immobilisation devices is the plaster of paris bandage which has been known and employed in the art for years for the purpose of immoblising the limb of patient. In general, the prior art plaster of paris bandage comprises an endless strip of gauze or the like fabric which constitutes a substrate upon which a layer or coating of of plaster of paris is deposited. This provides a ready-to-use article capable of being employed simply dipping it in water and then wrapping it around the patient's limb to be immobilised to form what is known as a cast.
Unfortunately, plaster of paris bandages suffer from a basic drawback arising out of the fact that plaster of paris possesses the characteristics of being extremely sensitive to water. Hence, the person wearing a cast made of plaster of paris has to be extremely careful at all times to protect it from water. This makes matters very difficult for the patient concerned since he or she cannot with impunity perform simple everyday acts which, in normal conditions would come naturally to them, such as having a bath or taking a shower.
Secondly, prior art plaster of paris bandages suffered from the drawback of weight. Plaster casts made from plaster of paris bandages tended to be very heavy which made it extremely uncomfortable for the wearer over a protracted period of time. What is more, in addition to their weight, prior art orthopaedic immobilisation devices were in general not porous. Hence in the summer in warm climates, the perspiration generated by the user of such devices did not evaporate but remained trapped underneath the device on the surface of the skin of the wearer. Over a prolonged period, this frequently caused irritation and itchiness to occur.
In view of the inherent drawback of water sensitivity of prior art orthopaedic immobilisation devices made from plaster of pan's, efforts continued to be made to improve these devices. One such improvement is described in and formed the
•
subject of Indian Patent No. 148709 of Johnson & Johnson. This Indian patent provided a water-resistant orthopaedic bandage comprising a hardenable plaster of paris composition including a reactive silicone polymer supported on a known flexible carrier wherein the plaster of paris content ranged from 100 to 600 grams per square yard of the carrier and the reactive silicone polymer ranged from 0.5 to 10 parts per hundred parts of plaster of paris.
The Johnson & Johnson bandage was only slightly less heavy than hitherto known bandages. However, the major problem which it exhibited was that although the water resistance was better, the bandages had virtually no porosity. This fact nullified the advantage of having a slightly better water-resistant bandage because in the event that the cast got wet, the cast might dry on the outside but because the plaster was not porous, it remained damp on the inner side which was in contact with the wearer's skin. This made it very uncomfortable for the wearer.
Other efforts to remove the drawbacks inherent in plaster of paris orthopaedic immobilisation devices were also made. These attempts were geared at the replacement of the plaster of paris component of the bandages by alternative substances which provided better water resistance. The results of these efforts are evidenced, inter alia, in Indian Patents Nos. 143546 and 147226 which made-use of synthetic chemical cements. The procedure involved the coating of one synthetic component on to a length of fabric such as gauze and adding the other component to the water in which the bandage to be employed on a patient had to be dipped. These bandages when made into plasters were fairly water-proof but the major drawback to them was that they took too long to set and were not porous enough to make the wearer comfortable.
During the 1970's, a new type of orthopaedic immobilisation article appeared in the market. This comprised a bandage in which a fibreglass fabric substrate was coated with the reaction product of isocyanates and polyols. Regretably, these bandages did not find favour with orthopaedic surgeons who, accustomed as they were to using the prior art plaster of paris bandages, disliked the newer orthopaedic immobilisation articles which they found bulky, slow to set and tacky. In addition, the fact that these bandages incorporated a fibreglass fabric base, they were difficult to cut when it was time to have the plaster removed.
In view of the reservations of many orthopaedic surgeons to bandages with a synthetic component coated on the fabric substrate, successive efforts were made to overcome the drawbacks to which the surgeons objected. These efforts did indeed overcome some of the drawbacks and the usage of such bandages grew but the latter were not universally accepted as meeting every orthopaedist's precise requirements.
One such bandage which came out of these efforts forms the subject matter of prior Indian Patent No. 177417. This Indian patent provided an orthopaedic article comprising a fabric sheet and a water-curable isocyanate-functional prepolymer resin coated on to the fabric sheet, said pre-polymer resin having a stable dispersion of hydrophobic polymeric particles therein.
Prior art bandages such as that of Indian Patent No. 177417 suffered a number of problems essentially because the fabric substrate employed therefor was made of fibreglass or a comparable material. Fibreglass is not a soft material. In fact, it is a rather rough one and so bandages where the substrate was fibreglass were very harsh on a patient's skin and therefore most uncomfortable for him. Moreover, because fibreglass does not adhere well to polyurethanes, it became the practice to abrade purposely the fibreglass in order to promote better adherence between the substrate and the coating thereon.
Furthermore, fibreglass happens to be one of the heavest yarns, that is to say, it has a very high density in comparison to other materials. As a result, the overall weight of these prior art bandages went up. Added to that was the reduced ability of the resin to adhere to the fibreglass which meant that an increased amount of resin had to be applied to the substrate making the weight of the prior art bandages heavier and therefore more uncomfortable for a wearer.
Fibreglass being a synthetic material is very difficult to cut. It was thus found that bandages such as those of Indian Patent No. 177417 which employed a fibreglass substrate could not be cut by hand saw as used to be the case of the older plaster of paris bandages. In order to remove a cast having a fibreglass substrate, it was necessary to cut it away using an oscillating plaster saw. In doing this an oscillating plaster saw generated a lot of fibreglass dust which was very harmful for the lungs if inhaled by either the patient or orthopaedic doctor. A still further drawback resided in the fact that after a fibreglass bandage is removed from a patient's limb, it cannot be burned in an incinerator along with other hospital waste as it is now mandatory to do.
Other drawbacks of prior art bandages employing fibreglass as a substrate reside in the fact that the fabric was not woven in the required width but was woven and/or knitted on wide looms known as Raschel Machines in in widths of 1 meter or more and then slit to the required width of 7.5 cm to 12.5 cm. This caused the cut threads at the slit edges to protude out of the fabric and when coated with the polyurethane adhesive, these hardened into a number of sharp points which caused severe discomfort to any wearer of the bandage by irritating, abrading or puncturing his skin.
Yet again, prior art bandages were made purposely using coarse counts of fibreglass yarn mostly of the order of 800 to 1200 denier in order to achieve better green strength and better cured strength. These coarse thick yarns made the bandages difficult to apply and wrap around the tapered or irregularly shaped body parts.
Most of the more sophisticated prior art bandages were developed by and manufactured for use in advanced countries where the climate is temperate to downright cold. That being so, the aspect of storage stability in hot and/or humid climates of the tropics was never taken into account since it was never thought of. As a result, prior art bandages tend to evince very poor shelf life in tropical countries and in less than six months more than 50% of imported bandages become unusable in the tropics. Hence, some bandages come with the labelled instructions "To Be Kept In Refergrator At Or Below 25° C".
The basic object of the present invention is to remove the shortcomings and deficiencies of the prior art and to provide an improved orthopaedic article for the immoblisation of the limb of a patient which has none of the disadvantages of the prior art.
Specifically, it is the object of the present invention to provide an improved orthopaedic article for the immoblisation of the limb of a patient which is extremely user friendly, such user friendness being evinced in an article which is gentle on the skin of the user, light-weight and thus overall more comfortable and yet having increased strength over prior art bandages to provide adequate support and immobility to the limb to which it is applied.
A further object of the invention resides in an orthopaedic article for the immoblisation of the limb of a patient which avoids the sharp edges and protruding fibres of prior art orthopaedic articles which made such prior art articles so uncomfortable for users thereof.
A still more specific object of the invention is an improved orthopaedic article for the immoblisation of the limb of a patient which, by selection of an appropriate substrate
and the application thereto of a coating of specially selected curable resinous material, provides the improved orthopaedic article.
Yet another object of the invention is the provision of an improved orthopaedic article for the immoblisation of the limb of a patient which can be easily applied to and removed from the limb in question and which is particularly suitable for employment in hot and tropical climates without subjecting the wearer to problems of discomfort associated in the past with prior art orthopaedic articles.
A further object of the invention is the provision of an improved orthopaedic article for the immoblisation of the limb of a patient which is storage stable and exhibits extended shelf life even in tropical climates.
Towards achieving these objects, the applicant has conducted his research under two aspects, first in respect of the fabric forming the substrate in respect of such orthopaedic articles and secondly, from the point of view of the water-curable resinous coating applied to such substrate. The research conducted was directed to the provision of a substrate and a coating which were not only compatible with each other but which, in combination, also exhibited the qualities desired for such an improved orthopaedic article including an enhanced shelf life.
In general, prior art orthopaedic bandages employed substrates made of fibreglass which, as stated earlier, is one of the heaviest yarns with very high density, all of which made it very unsuitable for an orthopaedic bandage and most uncomfortable for a user of an orthopaedic bandage made therefrom. Moreover, it was believed that the higher the denier of the fibreglass yarn, the better the performance which is why earlier patents for orthopaedic articles showed a preference for coarse denier fibreglass yarns.
With such an established preference for coarse denier yarns, it would have been quite reasonable to expect the applicant to confine his investigations to such yarns. In fact, it reinforces the novelty of the present invention that the applicant decided to ignore and go beyond the accepted theory and to investigate the suitability of fabrics made from fine denier yarns other than fibreglass.
Thus, as opposed to the prior art which employed 800 to 1200 denier fibreglass yarn, the applicant has discovered that by employing fabric made from 100 to 500 denier yarn for the substrate, a cast bandage not only lighter in weight but of remarkably soft texture can be produced which bandage surprisingly evinced better storage stability in hot and humid climates than fibreglass bandages. In this connection, it is preferred to employ fabric made from yarns which have a greater number of filaments for the same denier. For example, if a 300 denier yarn is selected, it is preferred to employ a 300/144 yarn to a 300/96 yarn or a 300/96 yarn to a 300/36 yarn. The reason for this is that the greater the number of filaments for a given final count of the yarn, the finer the individual filaments would be. This has been found to enhance the desired property of softness in the resultant substrate over substrates known in the prior art.
The applicant has established that the fabric from which the substrate of the orthopaedic article of his invention is made may be prepared from yarns of any of a number of natural or man-made fibres. These include cotton, rayon, jute, hemp, sisal, flax, polyethylene terephthalate, polypropylene, nylon, polyurethane, P.O.Y., polyester, Elastane, rubber thread fibres, aramid fibres, carbon fibres or blends of any of these.
For example, one such preferred blend comprises polyester yarn with Elastane yarn. Elastane is a polymeric elastic yarn made of a polyurethane elastomer and, therefore, evinces good compatibility with the resin used for coating the substrate. Where Elastane is used, it may be used either per se or covered by or intermingled
ith other yarns to enable easier handling. For the reasons mentioned, it is preferred to use low denier Elastane in order to get less stretch.
However, the yarn most preferred for preparation of the fabric from which the substrate of the applicant's orthopaedic article is made is fully drawn multifilament polyester yarn.
In a still further preferred embodiment, the novel fabric consists of a single-width knitted polyester fabric having fast edges. This provides the advantage that when such fabric is made into the substrate which constitutes the orthopaedic article or bandage, the width of the fabric is equal to the width of the substrate or bandage thereby avoiding the need to cut the fabric to the desired width of the substrate. When a fabric knitted out of such novel yarn is made into a substrate for a casting bandage, the softness of the bandage is remarkably increased.
In addition to the yarn content of the fabric forming the substrate of his improved orthopaedic article, the applicant has also investigated the actual weave of earlier substrates in which the spaces between the yarns comprising the fabric were sufficiently narrow to be entirely clogged by the resin when the latter was applied thereto. The applicant discovered that if the substrate were to be prepared from fabric knitted on crochet knitting machines, such substrate was found to have larger spaces within the weave thereof which did not get completely blocked when the resin was coated thereon. A substrate prepared from fabric produced in this manner was found to result in a casting bandage which was porous but nevertheless possessed more strength while it was drying and setting and comparable weight bearing capacity to prior art bandages.
It was found that a similar porous effect could be obtained when the fabric of the substrate was prepared on a raschel knitting machine or employing a needle loom.
Alternatively, it was possible to employ either a thicker fabric into which holes of an enlarged diameter were physically punched or even a net-like fabric.
The second area of research by the applicant related to the water-curable resinous coating applied to such substrate. As an initial investigation, the applicant researched water-curable isocyanates employed for the article of prior Indian Patent No. 177417. It was found that that TDI based isocyanates are toxic and require careful storage at low temperatures. Accordingly, the study of such TDI based was abandoned and other non-TDI isocyanates were studied and taken up for trials.
To that end, the applicant examined aliphatic and aromatic isocyanates. It was found that aliphatic isocyanates cured far too slowly which made it impractical to obtain the required properties for the provision of a polyurethane precursor for application to the proposed orthopaedic article. Furthermore, the handling characteristics of aliphatic isocyanates left much to be desired. This led the applicant to investigation of aromatic isocyanates.
The applicant's research was conducted with the object of obtaining a water- curable polyurethane precursor which displayed increased stability at higher ambient temperatures such as those usually encountered in tropical climates and, therefore, possessed a longer shelf life than precursors of the prior art.
These efforts by the applicant have resulted in a water-activated isocyanate prepolymer comprising a balanced combination of an aromatic isocyanate and a polyol in a specific ratio by weight conforming to the percentage of the weight of the NCO group in the resultant prepolymer, optionally in the presence of a catalyst therefor and one or'more initiators, accelerators and excipients.
The novelty of the present invention resides in the provision of an improved orthopaedic article or device for the immoblisation of the limb of a patient which comprises a specially created fabric substrate upon which a water-activated
isocyanate prepolymer comprising a balanced combination of an aromatic isocyanate and a polyol in a specific ratio by weight is applied. Such ratio will vary depending on the precise isocyanate and polyol employed but would generally be in the range of from 1 : 1 to 1.8 : 1.
Accordingly, the present invention provides an improved orthopaedic article for the immoblisation of the limb of a patient which comprises an endless substrate made from fabric knitted on a crochet or raschel knitting machine or a needle loom from 100 to 500 denier yarn of natural or man-made fibres or blends thereof having applied to one surface thereof a water-curable isocyanate prepolymer comprising a balanced combination of an aromatic isocyanate and a polyol in a specific ratio by weight of from 1 : 1 to 1.8 : 1 corresponding to the desired percentage by weight of the NCO group in the prepolymer, said prepolymer optionally containing a predetermined amount of strengthening agents such as herein described.
The natural or man-made fibres from which the 100 to 500 denier yarns are made include cotton, rayon, jute, hemp, sisal, flax, polyethylene terephthalate, polypropylene, nylon, polyurethane, polyester, rubber thread fibres, aramid fibres, carbon fibres or blends of any of these.
A particularly preferred yarn blend comprises a blend of polyester and polyurethane yarn. However, the yarn most preferred for preparation of the fabric from which the substrate of the orthopaedic article is made is fully drawn fine denier multifilament polyester yarn. When knitted from such yarn, the substrate exhibits a remarkable degree of increased softness.
According to a preferred embodiment, the fabric of said substrate comprises a single-width knitted polyester fabric having fast edges, the width of the knitted fabric being equal to the width of the substrate constituting the bandage.
The present invention also provides a process for the manufacture of an improved orthopaedic article for the immoblisation of the limb of a patient which comprises applying a water-curable isocyanate prepolymer comprising a balanced combination of an aromatic isocyanate and a polyol in a specific ratio by weight of from 1 : 1 to 1.8 :1 corresponding to the desired percentage by weight of the NCO group in the prepolymer to one surface of an endless substrate fabric knitted on a
crochet or raschel knitting machine or a needle loom from 100 to 500 denier yarn of natural or man-made fibres or blends thereof to form a coated substrate, wherein said prepolymer optionally contains a predetermined amount of strengthening agents such as herein described, and storing the coated substrate in a moisture-proof environment.
Although it does not form part of the invention, the prepolymer applied to the substrate can be prepared by subjecting a mixture of an aromatic isocyanate and a polyol in the said specific ratio by weight to controlled heat to obtain the desired prepolymer having a predetermined percentage of the weight of the NCO group. By the appropriate selection of the aromatic isocyanate and polyol, the water curable polyurethane prepolymer is able to evince greater stability at higher ambient temperatures as are normally encountered in tropical climates. This provides a significant advantage when employing such prepolymer in the manufacture of the casting bandage of this invention.
Suitable polyols are those found to provide greater stability at room temperature for the resultant precursor. These include the polyether and polyester polyols and it is preferred to use the medium and low molecular weight polyether polyols as these afford enhanced strength and stability to the coated substrate.
Optionally, the reaction of the aromatic isocyanate and the polyol is effected in the presence of a surfactant and/or a catalyst for the reaction. Also present may be one or more conventional initiators, accelerators and/or excipients.
The preferred initiator or accelerator used is benzoyl peroxide but it is used at a very low percentage.
The strength of the casting bandage can be increased by adding to the prepolymer prior to application thereof to the substrate a predetermined amount of one or more strengthening agents such as herein described.
Examples of such said strengthening agents are calcium carbonate, small fibres of polyester, nylon or polypropylene or other conventional strengthening agents.
Examples of such fillers or bulking agents include hollow glass beads, hollow microspheres, gas-filled microspheres or other conventional strengthening agents. However, a significant feature of the casting bandage of the present invention is thai no such strengthening or bulking agents are normally required since the desired degree of strength is provided by the unique fabric employed for the substrate.
The invention will be described in greater detail in the following Example..
EXAMPLE
To 160 grams of aromatic socyanate in a reaction vessel there were added 100 grams of poly ether polyol. The ingredients were mixed together and mixture then subjected to controlled heating to a temperature in the range of 80 °C to 100°C. in the presence of Benzoyl Peroxide as catalyst until a prepolymer having a predetermined percentage of the weight of the NCO group was formed (eg 16%). To the thus formed precursor there were added 20grams hollow glass beads and 10 grams hollow microspheres as strengthening agents.
The polyurethane precursor thus prepared was then removed form the reaction vessel, stored for a predetermined period of time and later, while still in fluid condition, coated on to a fabric substrate made of fully drawn 300 denier/ 96 filaments multifilament polyester yarn knitted on a crochet knitting machine of between 180 to 300 grams per meter square knitted in the required width of the bandage.
The coated substrate comprising a casting bandage was thereafter rolled on a core, placed within a pouch and the pouch heat sealed. The heat sealed pouch containing the rolled bandage was placed within another pouch which was likewise heat sealed. The sealing was checked and the sealed pouches were labelled with the batch number, date of manufacture, expiry date, size, price and other labelling information
as required. Optionally, several sealed pouches containing coated and rolled bandages can be packed further into an overall outer metal or plastic container or cardboard box.
To determine the shelf life of the coated substrates, the latter were subjected to a procedure known as accelerated ageing. Selected pouches within which the coated substrates were heat sealed were maintained at varying temperatures as follows:
a) Room Temperature ( 25° C. to 30 ° C.)
b) Hot Temperature (50° C.)
c) Accelerator Ageing Temperature (70° C.)
The RH was also monitored and recorded.
In the normal course of transit or during storage, the coated substrates are not likely to be subjected to temperatures as high as 70° C. However, by exposing them to such temperatures, it was possible to assess the viability of the coated substrates and to extrapolate the expected shelf life thereof at room temperature. For example, if the coated substrate did not deteriorate or cure for three weeks at 70° C. or three months at 50° C., it was possible to predict a shelf life of three years for the product if maintained at room temperature.
After the accelerated ageing procedure was complete, the properties of the poly urethane precursor coated upon the substrate were tested. Essentially, this test was to ascertain the free NCO percentage remaining in the precursor and to determine whether the precursor was still in pasty or liquid form or had cured and therefore solidified as result of the heat.
As part of an effort to ensure that the improved orthopaedic article or casting bandage of the present invention is preserved in optimum condition for the end user, the applicant has also devised a novel packaging enclosure for the polyurethane precursor coated substrates.
In the past, coated bandages were sealed individually within stiff pouches or envelopes made of polyethylene having rather sharp edges and corners. As many as ten to twenty individually sealed pouches were then packed into a larger outer carton in very close proximity to one another. As a result, during transit or movement, the sharp corners of one individual pouch frequently punctured the envelopes or the pouches of adjacent to it. This would ruin the sealed condition of the punctured pouches and allowed the ingress of moisture thereinto leading to premature curing of the coated substrates which were rendered unusable thereafter.
In this connection, it should be noted that the polyurethane precursor if maintained at 25 ° C. and 65% RH for a period of from 4 to 12 hours will cure within the pouch and no amount of effort will cause the rolled bandage to unroll. The situation is aggravated by the fact that polyethylene is permeable to moisture and has a much higher moisture vapour transmittal rate (MVTR) in comparison to other packaging material.
Some efforts have been made to improve the packaging of polyurethane casting bandages but even these are not suitable keeping in view the nature of the product. Packaging for polyurethane casting bandages currently available comprise a single pouch of thick gauge aluminium foil laminated with polyester film on the outside and heat sealable film on the inside. The thick aluminium foil is brittle and tends to break or tear even under the least pressure permittng ingress of moisture. This causes the ready-to-set polyurethane precursor coated on the bandages to cure and make the bandages hard and useless.
Towards overcoming the defects of earlier packaging of precursor-coated substrates, the applicant has created an improved packaging and this is described in greater detail with reference to the accompanying drawings in which:
Figure 1 represents an isometric view, partly in section, of the single-pouch packing of prior art casting bandages;
Figure 2 represents an isometric view, partly in section, of the improved multi-envelope packaging for polyurethane precursor-coated casting bandages of the present invention;
Figure 3 represents an isometric view, partly in section, of a further embodiment of the improved multi-envelope packaging for polyurethane precursor-coated casting bandages of the present invention;
Figure 4 represents a flowsheet illustrating the various stages in the preparation of the novel polyurethane precursor-coated casting bandages of the present invention from commencement to final packaging thereof; and
Figure 5 illustrates a preferred design of weave of knitted fabric employed for the substrate of the novel polyurethane precursor-coated casting bandage of the present invention.
The prior art packaging of Figure 1 clearly shows a coated casting bandage 10 sealed within an individual polyethylene envelope 12.
Figure 2 of the drawings discloses an improved coated substrate 14 according to the present invention sealed within a first or inner moisture-proof pouch 16. This pouch is made of a multi-layered laminated heat sealable film comprising at least one layer of an elastomeric polymer such as LDPE, LLDPE, HOPE or other thermoplastic
polymers laminated with one or more layers of metallised film, aluminium foil, paper or polyester film. Preferably, inner pouch 16 includes at least one layer of aluminium foil and should consist of a minimum of three laminated layers.
Inner pouch 16 is located within an outer sealed pouch 18 which is likewise made of a flexible material which is virtually impermeable to water vapour and which is neither rigid nor brittle. As in the case of inner pouch 16, outer pouch 18 is made of a multi-layered laminated heat scalable film comprising at least three layers of metallised film, aluminium foil or paper located between other layers of polymeric film. Preferably, outer pouch 18 contains at least one layer of aluminium foil.
As shown in Figure 2, outer pouch 18 is provided within a larger overall external packaging envelope 20. It will be observed that external packaging envelope 20 is large enough to make provision for a plurality of coated substrates 14 within their inner and outer pouches 16, 18.
Figure 3 illustrates an alternative embodiment of the packaging shown in Figure 2 in which a coated substrate 14 located within its inner and outer pouches 16, 18 is provided within a container 24 of metal or plastics having an air-tight, moisture proof lid 22 fitted thereon. This may also be a corrugated carton.
Preferably, the inner pouches 16 and the outer pouches 18 are packed under vacuum or flushed with dry air or nitrogen in order to increase further the shelf life of the coated substrates 14. These steps for ensuring enhanced shelf life can be carried out in any combination and in any order. The inner and outer pouches 16, 18 may also contain a desiccant bag filled with any suitable desiccant material for example silica gel, molecular sieves or calcium chloride. This desiccant will absorb any humidity permeating the pouch so that it does not reach the bandage and will increase the storage stability of the bandage.
The improved packaging produced by the applicant is not restricted to the specific material described herein for manufacture of the pouches. Any equivalent material having the same properties could be substituted without affected adversely the invention in question.
The flow chart of Figure 4 is pre-eminently clear in itself and requires no elucidation.
Figure 5 illustrates by way of example a preferred design of weave of knitted fabric employed for the substrate of the novel polyurethane precursor-coated casting bandage of the present invention. However, it must be understood that any other comparable weave or knitted pattern could be employed with equal effect.
For a practical application of the improved orthopaedic article of the present invention, the following description is provided by way of instructions. The patient is made to wear stockinette and then cotton wool or orthopaedic cast padding is wrapped on the part where cast is to be applied. Then the required amount of water is taken in a container and the outer pack of the bandage is opened. Then with gloved hands the outer and inner pouch of bandage is opened and bandage taken out. It is immediately dipped in water for 1 - 3 seconds & bandage squeezed lightly. Now the bandage is wrapped around the fractured limb without tightening and the desired shape is given while soft. It generally sets hard in 3 to 8 minutes of taking out of water but the preferred version sets in 4 to 6 minutes.
The improved orthopaedic article of the present invention is a versatile product having multiple uses. It can be used by orthopaedic surgeons for short or long time immobilisation of a limb. It can also be used as a do it yourself (DIY) item for the repairs of broken of leaking pipelines such as water pipes without having to shut down the entire water flow line and as a repair and maintenance tool to mend broken articles. It can also act as strong reinforcing tape for example for broken hockey
sticks and similar articles of household or industrial use whenever a proper reinforcement or adhesive is not immediately available.
The polyurethane casting bandage of the present invention is endowed with long shelf life and a soft feel as an immobilising product. All these qualifications should change the image of orthopaedic plasters by presenting something which is more acceptable to a patient and is less likely to generate perspiration and irritation in the wearer.

WE CLAIM:
1. An improved orthopaedic article for the immoblisation of the limb of a
patient which comprises an endless substrate made from fabric knitted on a
crochet or raschel knitting machine or a needle loom from 100 to 500 denier yarn
of natural or man-made fibres or blends thereof having applied to one surface
thereof a water-curable isocyanate prepolymer comprising a balanced
combination of an aromatic isocyanate and a polyol in a specific ratio by weight of
from 1 : 1 to 1.8 : 1 corresponding to the desired percentage by weight of the NCO
group in the prepolymer, said prepolymer optionally containing a predetermined
amount of strengthening agents such as herein described.
2. An improved orthopaedic article as claimed in claim 1 wherein said natural
or man-made fibres include cotton, rayon, jute, hemp, sisal, flax, polyethylene
terephthalate, polypropylene, nylon, polyurethane, polyester, rubber thread fibres,
aramid fibres, carbon fibres or blends of any of these.
3. An improved orthopaedic article as claimed in claim 1 or 2 wherein blend of
yarns comprises a blend of polyester and polyurethane yarn.
4. An improved orthopaedic article as claimed in any of claims 1 to 3 wherein
the yarn from which the fabric forming the substrate is prepared is preferably
polyester yarn.
5. An improved orthopaedic article as claimed in any of claims 1 to 4 wherein
said strengthening agents are selected from one or more of calcium carbonate,
small fibres of polyester, nylon or polypropylene or other conventional
strengthening agents.
6. An improved orthopaedic article for the immoblisation of the limb of a
patient substantially as herein described.
7. A process for the manufacture of an improved orthopaedic article for the
immoblisation of the limb of a patient which comprises applying a water-curable
isocyanate prepolymer comprising a balanced combination of an aromatic
isocyanate and a polyol- in a specific ratio by weight of from 1 : 1 to 1.8 : 1
corresponding to the desired percentage by weight of the NCO group in the
prepolymer to one surface of an endless substrate fabric knitted on a crochet or
raschel knitting machine or a needle loom from 100 to 500 denier yarn of natural
or man-made fibres or blends thereof to form a coated substrate, wherein said
prepolymer optionally contains a predetermined amount of strengthening agents
such as herein described, and storing the coated substrate in a moisture-proof
environment.
8. A process as claimed in claim 7 wherein said polyol is a polyether polyol.
9. A process as claimed in claim 7 or 8 wherein said strengthening agents are
selected from one or more of calcium carbonate, small fibres of polyester, nylon or
polypropylene or other conventional strengthening agents.
10. A process for the manufacture of an improved orthopaedic article for the
immoblisation of the limb of a patient substantially as herein described.

Documents:

63-DEL-2001-Abstract.pdf

63-DEL-2001-Claims.pdf

63-del-2001-complete specification (granted).pdf

63-del-2001-correspondence-others.pdf

63-del-2001-correspondence-po.pdf

63-DEL-2001-Description (Complete).pdf

63-DEL-2001-Drawings.pdf

63-DEL-2001-Form-1.pdf

63-del-2001-form-13.pdf

63-DEL-2001-Form-2.pdf

63-del-2001-form-3.pdf

63-del-2001-form-4.pdf

63-del-2001-form-5.pdf

63-del-2001-gpa.pdf

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Patent Number

230956

Indian Patent Application Number

63/DEL/2001

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

28-Feb-2009

Date of Filing

24-Jan-2001

Name of Patentee

SABHARWAL MANISH

Applicant Address

117/H-2/160,PANDU NAGAR,KANPUR-208 005,INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	SABHARWAL MANISH	117/H-2/160,PANDU NAGAR,KANPUR-208 005,INDIA.
2	SABHARWAL,AJIT RAI	B-4,SARVODAYA NAGAR,KANPUR-208 005,INDIA

PCT International Classification Number

A61F 005/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA