Orthopedic supports and material for making same

Abstract: Orthopedic supports (10, 36, 42, 46) are made from a flexible, resilient composite material (12) which includes a base layer (28) of a flexible, closed cell elastomeric material such as neoprene rubber in thin sheet form, with a multiplicity of relatively large air holes (30) extending through the depth of the sheet and dispersed across the surface of the sheet. A skin-­ protecting first layer (32) of a soft, flexible, stretchable porous knitted fabric is adhered to a first face of the base layer (28). A protective second layer (34) of a flexible, stretchable porous knitted fabric is adhered to the second face of the base layer (28). The composite material (12) is porous to air and water passing through the depth of the composite layer. Orthopedic supports (10, 36, 42, 46) made from the material (12) are sufficiently elastic to provide compression around a body part supported by the composite material (12) in its stretched condition. The composite material (12) is sufficiently porous to ventilate the supported body part during use such that elasticity and support is provided while heat discomfort and perspiration are prevented. Another embodiment includes a prosthetic stocking (62) made from the composite material (64) which is porous to fluids to provide air circulation during use to avoid heat discomfort.

Description: FIELD OF THE INVENTION This invention relates to a composite material for use in making orthopedic supports having improved properties during use. More particularly, the composite material provides a novel combination of elasticity and good compression support, shear resistance, and porosity to air and water sufficient to avoid heat discomfort and perspiration of the user during prolonged periods of use. BACKGROUND OF THE INVENTION Orthopedic supports are available in many forms. A common orthopedic support is a rigid knee brace worn by persons who suffer knee instabilities and by those engaged in sporting activities to prevent injuries to the knee. A common purpose of the knee brace is to provide exterior support for the knee to prevent any unnatural movements of the knee joints which could injure or reinjure the knee ligaments, while allowing the normal swinging movement of the knee joint. Such knee braces are commonly used for post-operative patients who have had knee surgery. These knee braces commonly include metal bars and pivot joints to provide a rigid means of support. Such knee braces are sold by a physician's prescription only and require a skilled orthotist to fit them properly to the patient. Other orthopedic supports are the so-called "soft supports" which are sold in drug stores, hospitals and doctors' offices. The soft supports provide a modest amount of support for an injured joint. These types of supports do not include rigid metal bars or stays, but are simply made from a soft, stretchable material. They are often purchased without prescription or the need for skilled professional fitting. The soft orthopedic supports have been used for a number of years and have been commonly available as supports for the knee, ankle, thigh, wrist, elbow, chest or lower back. These soft orthopedic supports are normally worn for sprains and strains, arthritis, tendonitis, bursitis, inflammation, or to reduce discomfort during post-operative use or to treat post-trauma discomfort. The soft orthopedic supports are often made from neoprene rubber. This material is desirable because of its combination of favorable properties useful in orthopedic supports. Neoprene rubber has good elasticity and a relatively high density, properties which combine to provide good compression support and resistance to shear forces. A soft support or physiological protector, comprising a laminated structure preferably using NEOPRENE as a base material, is disclosed in WO-A-8101240, disclosing the closest prior art. Neoprene rubber is a closed cell material and therefore does not dissipate heat very well during use. Its closed cell characteristics can be useful in retaining heat during use by reflecting emitted heat back into the bones and joints of the affected area. This localized concentration of heat can aid venous flow, help reduce edema, and make the soft tissues less susceptible to injury. Although use of neoprene rubber in orthopedic supports can be useful because of its ability to concentrate heat, the natural tendency of the closed cell material to prevent heat dissipation creates problems for the user. The neoprene rubber supports are stretched when applied so that the material can compress around the affected area. This tight compression fit combined with the high density of the material and the lack of air circulation and dissipation through the material, causes heat discomfort and perspiration and often leads to heat rashes. Prolonged use of such neoprene rubber supports can cause the user to perspirate constantly, causing discomfort to such a degree that the user often stops wearing the support prematurely. In effect, the material itself dictates the length of time that the orthopedic supports can be worn. It is not uncommon for users to stop wearing such supports after about one to two hours. Replacing the closed cell neoprene rubber with an open cell material does not provide an acceptable solution to the heat discomfort problem. Open cell materials, such as sponge rubber or plastic foam materials such as high density polyester or polyurethane foams, are materials characterized by their ability to "breathe". That is, they are porous to air and water. Such materials can ensure good air circulation and good heat dissipation and absorption of body fluids during use. However, such open cell materials do not inherently possess the high density necessary for the materials to provide sufficient compressive strength to serve as an orthopedic support. Thus, there is a need for an orthopedic support having sufficient elasticity and density to offer a necessary level of compression support, while also dissipating heat during use sufficient to avoid undue perspiration and heat discomfort during prolonged use of the support. There is also a need to provide a liner for use with a prosthesis for an amputee. The process of custom molding a liner for the definitive prosthesis is time-consuming and expensive. Moreover, this cost is amplified because these liners wear out and require replacement by further custom-made liners. Further, if the patient gains or loses weight the volume of the stump changes; so there is an ongoing need to provide a liner that accurately and comfortably fits between the stump and socket of the permanent prosthesis. Closed cell material also can produce heat discomfort during long periods of use because of the closed cell material's inability to "breathe", i.e., to provide sufficient air circulation to the protected area. SUMMARY OF THE INVENTION Briefly, this invention provides a flexible, resilient composite material for use in making elastic orthopedic supports for supporting a body part by compression. The composite material includes a base layer of a flexible, elastomeric closed cell material in thin sheet form having a multiplicity of air holes extending through the depth of the sheet and dispersed across the surface of the sheet. A skin-protecting first layer of a soft, flexible, resilient porous fabric is adhered to a first face of the base layer. A protective second layer of a flexible, resilient porous fabric is adhered to an opposite second face of the base layer. The composite material is porous to air and water passing through the depth of the composite material. When used as an orthopedic support, it allows sufficient air circulation to avoid perspiration and heat discomfort during prolonged use. The air holes in the elastomeric base layer of closed cell material combine with the porous first and second layers of knitted fabric to enhance air circulation and reduce heat build-up during use. The high density of the closed cell material provides sufficient compression support for the affected area during use. The first and second knitted fabric layers provide elasticity on opposite sides of the elastomeric base layer. They reinforce the strength of the composite material to overcome any level of elasticity or strength lost because of the added hole pattern in the elastomeric base layer. Experimental use of orthopedic supports made from this composite material has demonstrated substantial improvements in absence of perspiration and attendant heat discomfort from long periods of use. The invention also includes novel orthopedic supports made from the new composite material. In addition, a prosthetic stump sock made from the composite material provides a useful combination of elasticity for compression-type support while being sufficiently porous to avoid heat discomfort and perspiration during prolong use. These and other aspects of the invention will be more fully understood by referring to the following detailed description and the accompanying drawings. DRAWINGS FIG. 1 is a side elevation view semi-schematically illustrating a knee support made from an orthopedic material according to principles of this invention. FIG. 2 is a semi-schematic perspective view of the knee support shown in FIG. 1. FIG. 3 is a cross-sectional view schematically illustrating components of a composite orthopedic material of this invention. FIG. 4 is a fragmentary plan view illustrating a perforated closed cell elastomeric layer of the composite material. FIG. 5 is a perspective view illustrating an elbow support made from the composite material. FIG. 6 is a perspective view illustrating a wrist support made from the composite material. FIG. 7 is a side view illustrating an ankle support made from the composite material. FIG. 8 is a side elevation view showing a completed prosthetic stocking made from a composite orthopedic material according to principles of this invention. FIG. 9 is a fragmentary schematic cross-sectional view taken on line 9-9 of FIG. 8. FIG. 10 is a fragmentary plan view illustrating a perforated closed cell elastomeric layer of the composite material. DETAILED DESCRIPTION FIGS. 1 and 2 illustrate a knee support 10 made from an orthopedic material according to principles of this invention. The orthopedic material is illustrated in FIGS. 3 and 4. The knee support is a soft orthopedic support made entirely from a flexible, resilient composite material 12 shown in flat form in FIGS. 3 and 4. The flat form composite material is folded over and seamed to form the finished tubular knee support 10 illustrated in FIGS. 1 and 2. Referring to FIGS. 1 and 2, a piece of the composite material 12 in flat sheet form is folded over on itself and cut inwardly from the middle of the overlapping long edges on the side opposite the fold. The cut-out portion is a V-shaped region extending from the overlapping long edges toward the fold at the opposite side. The overlapping edges along the central region of the folded material are fastened by left and right stitched seams 14 and 16, respectively. The overlapping long edges on the opposite side of the fold are fastened by a long upright seam 18. This produces an angular knee support of generally tubular form having an open top 20 and an open bottom 22. Peripheral stitching 24 at the upper edge and similar peripheral stitching 26 at the bottom edge provide finished edges for the completed knee support. The materials which comprise the composite material 12 are understood best by referring to FIGS. 3 and 4. The composite material includes a flexible and foldable elastomeric base layer 28 in thin sheet form made from a closed cell material. The preferred elastomeric closed cell material is neoprene rubber. The neoprene rubber layer 28 is perforated by a multiplicity of holes 30 dispersed across the surface of the neoprene rubber layer and extending through the entire depth of the neoprene rubber layer so that fluids can pass through the holes from one side of the layer to the other. The perforations 30 are not shown in FIG. 3 for simplicity. The hole pattern shown in FIG. 4 is somewhat exaggerated in relative size, but illustrates the preferred technique of forming the holes in a uniform pattern in which all holes are of uniform diameter and spaced apart uniformly across the face of the neoprene rubber layer. In one embodiment, the neoprene rubber layer has a 0,57 mm (0.090 inch) hole diameter with 6,35 mm (1/4 inch) on-center diagonal spacing between adjacent holes in the uniform pattern. Preferred neoprene materials are sold by Rubatex Corporation, Bedford, Virginia, and sold under stock numbers G-231-N, G-207-N, or R-411-N. These materials have a density in the range of about 160 Kg/m³ to about 480 Kg/m³ (about 10 to about 30 pounds per cubic foot). In experimental tests, these materials have provided good results when used in orthopedic supports. The size of the holes and their distribution across the face of the neoprene rubber layer are such that the holes can provide immediate heat dissipation during use of the material in a composite orthopedic support. The holes must not be so large or spaced so close together that the overall elasticity or density of the neoprene rubber layer is reduced beyond the ability of the material to provide sufficient orthopedic compression support during use. A useful hole pattern is one in which the total area of the holes in a given section of the flat-form material occupies between about 3% and about 10% of the overall area of the perforated sheet section. The preferred hole pattern occupies about 5% of the surface area of a given perforated sheet section. By increasing the aggregate area of the holes in a given sheet, elasticity and strength are reduced; but the density of the material can be increased proportionately to compensate and therefore maintain a necessary level of elasticity and resulting orthopedic compression force. The desired thickness of the neoprene rubber layer is about 3,17 mm (1/8 inch). Good results are obtained with sheet thicknesses in the range of about 1,6 mm (1/16 inch) to about 6,35 mm (1/4 inch). The preferred method for forming the hole pattern in the neoprene rubber layer is by a roller forming technique in which the roller (not shown) has a cylindrical outer surface with projecting punches in the desired hole pattern so that rolling the roller over the flat surface of the neoprene rubber sheet punches out holes in the desired pattern. The composite material also includes a soft, flexible, resilient, porous skin-protecting inner layer 32. The presently preferred material is known by the trademark Tricot. This material is a knitted flexible and foldable, stretchable cloth fabric which is porous to air and water because of the pores inherently formed by the knitted fabric. Thus, the individual pores in the perforated neoprene rubber layer are substantially larger in area than the individual pores formed by the knitted fabric. The holes in the neoprene rubber layer are larger in area by at least an order of magnitude. The composite material also includes a flexible and elastic, porous, protective outer layer 34 which is also made from a stretchable knitted fabric. The protective outer layer is preferably made from the material sold under the trademark Tricot. The inner and outer layers 32 and 34 also may be made from other stretchable knitted fabrics comprising nylon, dacron or other synthetic fibers. In the flat form material illustrated in FIGS. 3 and 4, the inner layer 32 and the outer layer 34 overlie opposite faces of the perforated neoprene base layer 28. After the neoprene rubber layer is perforated, the inner and outer fabric layers are bonded to opposite faces of the perforated base layer. A conventional adhesive provides the desired surface adhesion over the entire contacting surface areas of the perforated base layer and the adjoining knitted fabric layers 32 and 34. The adhesive does not disrupt the porosity of the perforated base layer and the knitted fabric layers 32 and 34. The knee support made from the composite material has sufficient porosity that internal heat build-up during use is essentially avoided. One experimental test of a knee support made with the composite material 12 of this invention has demonstrated that the knee support provides sufficient ventilation to be worn for a two hour period without causing undue perspiration or other heat discomfort. By comparison, the same knee support made with the identical composite material, except that the neoprene layer was not perforated, produced perspiration almost immediately and was uncomfortable to wear for the same two hour period. The knee support of this invention is believed to be capable of being worn indefinitely without perspiration or heat discomfort problems. The level of comparison support provided by the knee support of this invention also was sufficient for the intended purpose of the knee support. The knee support is sufficiently elastic and of sufficient density to provide the compression necessary to serve as a useful knee support. Any elasticity lost by perforation of the neoprene rubber layer can be compensated for by a proportionate increase in the density of the neoprene rubber layer. In addition, the inner and outer layers 32 and 34 of the resilient, flexible knitted fabric provide resilience on their own to reinforce the elasticity of the perforated neoprene rubber, so that the composite material has the necessary level of elasticity for orthopedic use. The inner and outer layers of resilient knitted fabric also add strength to the composite material. It has been discovered that elimination of the inner fabric layer does not provide a useful orthopedic support, because direct skin contact by the larger air holes in the perforated neoprene rubber layer is discomforting to the user. The inherently formed small pores in the knitted inner fabric layer provide good porosity for air circulation The inner resilient fabric layer enhances comfort as well as adding useful levels of elasticity and strength to the overall composite material. A preferred combination is provided by inner and outer knitted fabric layers, each having greater elasticity than the elasticity of the perforated neoprene rubber layer. The material comprising the inner and outer layers may have different elasticity in mutually orthogonal directions. The material can be used in combination with the perforated neoprene layer so that the resulting orthopedic support has greater stretchability laterally, i.e., in a direction parallel to its top and bottom edges while the resulting support has greater resistance to stretching longitudinally, i.e., perpendicular to its top and bottom edges of the support. FIGS. 5 through 7 illustrate further uses of the composite material 12 in orthopedic supports. FIG. 5 shows an elbow support 36 in which the composite material is folded and seamed along its length, with an intermediate seam 38 to form a somewhat L-shaped tubular elastomeric support. Top and bottom edges of the tubular support have stitched peripheral seams 40 for edge reinforcement. FIG. 6 illustrates a wrist support 42 made from the composite material 12 in which the material is folded and seamed lengthwise to form a straight tubular support having peripheral stitching 44 at its opposite ends for edge reinforcement. FIG. 7 illustrates an ankle support 46 made from the composite material. The ankle support is formed as a generally L-shaped tubular support with peripheral stitching 48 at its opposite ends, peripheral stitching 50 around an edge portion of the support that fits around the heel of the user, and intermediate stitching 52 fastening adjoining intermediate edges of the L-shaped ankle support. These orthopedic supports can be used to provide required levels of anatomical compression support while improving air circulation to the supported area sufficient to prevent the discomfort caused by perspiration and over-heating. The improved composite material of this invention is thus responsible on its own for improving the anatomical support provided by such orthopedic supports, because the user is able to wear the support indefinitely rather than removing the support prematurely because of heat discomfort. FIGS. 8 through 10 illustrate a further embodiment of the invention which comprises a prosthetic stump sock made from the flexible, resilient composite material which includes a base layer of a flexible, elastomeric closed cell material in thin sheet form having a multiplicity of holes extending through the depth of the sheet and dispersed across the surface of the sheet. A skin-protecting first layer of a flexible, resilient porous fabric is adhered to a first face of the base layer. A protective second layer of a flexible, resilient porous fabric is adhered to the second face of the base layer. The composite material is porous to air and water passing through the depth of the composite material. When the composite material is formed as a prosthetic stocking, it allows sufficient air circulation to avoid perspiration and heat discomfort during prolonged use. The holes in the elastomeric base layer of closed cell material combine with the porous first and second layers of knitted fabric to enhance air circulation and reduce heat build-up during use. The high density of the closed cell material provides sufficient compression support reinforced by the strength and elasticity of the first and second fabric layers so as to be useful as a prosthetic stocking. FIG. 8 illustrates a prosthetic stocking 62 made from the composite orthopedic material of this invention. The orthopedic material is illustrated in FIGS. 9 and 10. The flat form composite material is cut, folded over and seamed at 66 with peripheral edge stitching at 68 to form the finished prosthetic stocking illustrated in FIG. 8. The materials which comprise the composite material 64 include the flexible and foldable elastomeric base layer 70 in thin sheet form made from a closed cell material, preferably neoprene rubber. The neoprene rubber layer 70 is perforated by the holes 72 dispersed across the surface of the neoprene rubber layer and extending through the entire depth of the neoprene rubber layer so that fluids can pass through the holes from one side of the layer to the other. The composite material also includes the soft, flexible, resilient, porous skin-protecting inner layer 74, preferably Tricot. The composite material also includes the flexible and elastic, porous, protective outer layer 76 which is also made from a stretchable knitted fabric, preferably Tricot. The inner and outer layers 74 and 76 also may be made from other stretchable knitted fabrics comprising nylon, dacron or other synthetic fibers. In the flat form material illustrated in FIGS. 9 and 10, the inner layer 74 and the outer layer 76 overlie opposite faces of the perforated neoprene base layer 70. After the neoprene rubber layer is perforated, the inner and outer fabric layers are bonded to opposite faces of the perforated base layer. A conventional spray-on adhesive provides a desired surface adhesion over the entire contacting surface areas of the perforated base layer and the adjoining knitted fabric layers 74 and 76. The prosthetic stocking made from the composite material has sufficient porosity that internal heat buildup during use is essentially avoided. One experimental test of a prosthetic stocking made with the composite material of this invention has demonstrated that the prosthetic stocking provides sufficient ventilation to be worn for a two hour period without causing undue perspiration or other heat discomfort. By comparison, the same prosthetic stocking made with the identical composite material, except that the neoprene layer was not perforated, produced perspiration almost immediately and was uncomfortable to wear for the same two hour period. The prosthetic stocking of this invention is believed to be capable of being worn indefinitely without perspiration or other heat discomfort problems. The prosthetic stocking of this invention is sufficiently elastic and of sufficient density to provide the compression necessary to serve as a useful prosthetic stocking. Any elasticity lost by perforation of the neoprene rubber layer can be compensated for by a proportionate increase in the density of the neoprene rubber layer. In addition, the inner and outer layers 74 and 76 of the resilient, flexible knitted fabric provide resilience on their own to reinforce the elasticity of the perforated neoprene rubber, so that the composite material has the necessary level of elasticity of orthopedic use. The inner and outer layers of resilient knitted fabric add strength to the composite material. It has been discovered that elimination of the inner fabric layer does not provide a useful prosthetic stocking because direct skin contact by the perforated neoprene rubber layer is discomforting to the wearer. The inner resilient fabric layer enhances comfort as well as adding useful levels of elasticity and strength to the overall composite material. A preferred combination is provided by inner and outer knitted fabrics, each having greater elasticity than the elasticity of the perforated neoprene rubber layer. The material comprising the inner and outer layers also may have different elasticity in mutually orthogonal directions. The material can be used in combination with the perforated neoprene layer so that the resulting orthopedic support has greater stretchability laterally, i.e., in a direction parallel to the top edge of the prosthetic stocking while the resulting prosthetic stocking has greater resistance to stretching longitudinally, i.e., perpendicular to the top edge of the stocking. The composite orthopedic material can be used to provide a temporary prosthetic stocking as well as the permanent prosthetic stocking. These prosthetic stockings are used in the manner described above for the temporary and permanent stockings illustrated in FIGS. 1 through 7. The prosthetic stockings made with the composite material provide required levels of anatomical compression support while improving air circulation to the supported area sufficient to prevent the discomfort caused by perspiration and overheating. The improved composite material of this invention is thus responsible on its own for improving the anatomical support provided by the prosthetic stockings because the user is able to wear the stockings indefinitely rather than removing them prematurely because of heat discomfort.

Claims: A flexible, resilient composite material (12,64) for use in making elastic orthopedic compression supports for surrounding and supporting a body part by compression in which the composite material (12,64) comprises a porous base layer (28,70) of a flexible, closed cell elastomeric material in thin sheet form; a skin-protecting first layer (32,74) of a flexible, resiliently elastic porous fabric adhered to a first face of the base layer; and a protective second layer (34,76) of a flexible, resiliently elastic porous fabric adhered to an opposite second face of the base layer; characterised in that the porous base layer of closed cell elastomeric material has a multiplicity of holes (30,72) extending through the entire depth of the sheet and distributed across the surface area of the sheet, the closed cell elastomeric material (12,64) having sufficient elasticity and a density of at least 160 kg/m³ (10 pounds per cubic foot) to provide orthopedic compression support, in which the first (32,74) and second layers (34,76) provide a means for reinforcing the elasticity of the porous base layer (28,70) so that the composite material (12,64) consisting of the combination of said base layer (28,70), first layer (32,74), and second layer (34,76) maintains sufficient elasticity and density to provide a useful level of orthopedic compression support, and in which said composite material (12,64) is porous to air and water passing through the depth of the composite material (12,64) to provide a means of heat and moisture dissipation for the surrounded body part during use of such an orthopedic compression support. The article according to claim 1 in which the first (32,74) and second layers (34,76) are knitted fabrics having pores naturally formed in the fabric, and the individual holes (30,72) in the base layer have a substantially larger area than the area of the individual pores formed in the knitted fabric. The article according to claims 1 or 2 in which the base layer (28,70) is made of neoprene rubber. The article according to claims 1 or 2 in which the holes (30,72) occupy about three percent to about ten percent of the surface area of the base layer (28,70). The article according to claims 1 or 2 in which the thickness of the base layer (28,70) is about 0,158 cm (1/16 inch) to about 0,635 cm (1/4 inch). The flexible, resilient composite material of claim 1, characterised in that the composition material (12,64) is formed as a tubular orthopedic compression support for applying compression-type support to a surrounded body part in which the composite tubular support has sufficient elasticity and density to provide a useful level of orthopedic compression support, and in which the tubular composite support is porous to air and water passing through the depth of the composite material (12,64) from the surrounded body part to thereby provide a means of heat and moisture dissipation during use of such a tubular orthopedic compression support. An orthopedic support for supporting the knee (10), elbow (36), wrist (42), or the like, made from the composite material (12,64) of claims 1, 2 or 6, wherein the composite layer is overlaid and seamed (18) to form a tubular support open at both ends (20,22). An ankle support (46) made from the composite material of claims 1, 2 or 6, wherein the composite material (12,64) is overlaid and seamed (52) to form a generally L-shaped tubular support open at opposite ends. The article according to claim 1 in which the holes are substantially uniform in size and are spaced apart substantially uniformly across the surface of the base layer. The article according to claims 1 or 6 in which the density of the base layer (28,70) is about 160 kg/m³ (10 pounds per cubic foot) to about 480 kg/m³ (30 pounds per cubic foot. The article according to claim 6 in which the elastomeric closed cell base layer (28,70) comprises neoprene rubber. The article according to claim 6 in which the resulting orthopedic support has mutually orthogonal lateral and longitudinal dimensions, and in which the support has greater stretchability laterally than longitudinally.

Inventors: LERMAN MAX, LERMAN, MAX
Applicants: LERMAN MAX, LERMAN, MAX
Application year: 1988
Main classification: A61F13
IPC codes: A61F2, A61F13