Orthopedic device

1 2

The orthopedic device has both sides of the plastic ORTHOPEDIC DEVICE sheet member covered. The side covered with the insu

This is a division of application Ser. No. 600,082, filed lating layer is the inside surface of the device and is the July 29, 1975, now U.S. Pat. No. 4,006,741 which in side intended to be placed against the body surface turn is a continuation-in-part application of Ser. No. 5 during service. The other side (the outside of the de465,404 filed Apr. 29, 1974, now U.S. Pat. No. vice) is covered with a fabric layer (referred to herein as 3,906,943. the "outside" or "other" of "protective" which is pref

erably fabric and protects the plastic. The insulating BACKGROUND OF THE INVENTION jayer is bonded to the plastic and the outside fabric layer

This invention relates to orthopedic devices having 10 is bonded to the plastic sheet member. The outside broad medical applications. These devices are used to fabric layer is preferably between about 4 and 22 mils support, position, protect, immobilize and/or restrain thick.

portions of the body. ... BRIEF DESCRIPTION OF THE DRAWINGS

Orthopedic devices is a broad term that is used to described medical structures such as casts, splints, sup- 15 FIG-1 is a rectangular blank having a construction in ports, braces and other means utilized to support, immo- accordance with the present invention, bilize, restrain, protect and position body portions. FIG. 2a an enlarged cross section along the line 2—2 They are used in many fields, including the physical of FIG- \°? one embodiment of the mvention. medicine and rehabilitation field, general medicine, „ FIG; ^» an enlarged cross section along the line neurological field, and the veterinary field. They are 20 2~? °f FJ?-1 °f another embodiment of the invention, also used to prevent recurrance of previous disabilities, FIG- 3 is a perspective of a formed back support and to prevent discomfiture and subsequent disability. havmg a construction m accordance with the embodi

Different types of the known orthopedic devices TMTM5.1C*- ^ andt. e c . .....

have specific uses and it has been necessary to select a „ FIG; 4 » a Perspective of a formed arm qrimt havmg specificType of orthopedic device to meet the require- 25 ^jg*?"**TM m accordance wlth the embodiment of ments of a specific intended usage. The treatment of

fractures usually requires total immobilization. Casts When the insulating layer is a fabric, it may be a woven, made of Plaster of Paris (plaster) are commonly used for felted matted, batted or knitted fabric. When it is a this purpose. Plaster casts have the disadvantage that it 3Q woven fabric, it is preferably between about 10 mils and takes hours to harden, the cast is excessively heavy, it 22 mils thick. Some fabrics, e.g., felt, may be

has poor compression strength and is readily crushed or considerably thickner and provide cushioning. The broken, and it has poor resistance to water and poor preferred insulating fabric is a woven blend, preferably x-ray penetrability. Splints have been made of wood 50:50, of a high-temperature aromatic polyamide now and metal and even plastic. Those synthetic base ortho- 35 generically classified as an aramid, and a

pedic devices which have been proposed and/or intra- high-temperature cross-linked phenol-formaldehyde duced commercially by others have had disadvantages fiber, such as the no-burn fabrics marketed by Collins & inherent in some or all uses. Aikman Corp. which are blends of 50% Kynol and 50%

Orthopedic devices should desirably be lightweight. Nomex. Nomex is a trademarked product of the Du They should be capable of immobilizing a portion of the 40 Pont Company and is the high-temperature aromatic body when that is the intended purpose. Similarly, they polyamide. Kynol is a trademarked product of the should be capable of resiliant support and/or cushion- Carborundum Company and is a cross-linked

ing when that is required. The orthopedic device should phenol-formaldehyde fiber, such as that described in be capable of being formed in a practical manner and USP Pat. No. 3,650,102. An aramid fabric may also be without discomfort to the patient. Additionally, the 45 used. orthopedic device should not have properties which The insulated fabrics may be used in weights of about irritate the patient during the period in which it is in 4 oz. per square yard, up to about 16 oz. per square service. Orthopedic devices fulfilling these require- yarcj. The preferred weight is about 5 to 8 oz. per square ments are disclosed in my copending application, Ser. yard.

No. 465,404, filed Apr. 29, 1974. 50 The insulating layer preferably should have a coeffi

It is an object of this invention to provide orthopedic cient of heat transfer below about 2 cal/devices having wide applicability and a unique combi- sec/cm2/cm/°CX 10-4, and more preferably below nation of desirable properties. about 1.6 cal/sec/cm2/cm/°CX 10-4.

SUBJECT MATTER OF THE INVENTION When the msulatinS layer is a fabric layer>il is Prefer

55 ably affixed to the central plastic member with an adhe

The orthopedic device of the present invention is a sive, preferably a thermoplastic adhesive. Since rela

plastic sheet member having at least one side covered tively high shaping and molding temperatures, e.g, 400°

with a thermally insulating layer. The plastic sheet F, may be used to shape the orthopedic device, the

member is at least about 40 mils thick. The insulating thermoplastic adhesive should be one which will remain

layer is at least about 10 mils thick. It is capable of being 60 bonded to the fabric and to the central plastic member

molded (formed) with application of normal finger pres- at the temperatures used to heat and form the device. It

sure when the plastic is at a temperature above about is preferred that it should retain said property at temper

120° F. When the device is heated to substantially above atures above 200° F amnd for an added safety factor, it

its molding temperature, e.g. 165-350° F, and allowed is preferred that it should retain said property at above

to cool in air and ultimately on the patient as it is being 65 about 350° F for devices which will be shaped before

formed, the temperature at the outside of the insulating services.

layer is at least about 25° F cooler than the plastic mem- The outside adhesive may be a polyurethane; prefera

ber and preferably at least 40° F cooler. bly a flexible thermoplastic polyester type polyurethane 3 4

adhesive. This material also has the advantages of good without the possibility of movement is desired, rela

resistance to perspiration, washing and dry cleaning. tively thin foam layers e.g., between about 25 and 75

Although the polyester type polyurethanes are pre- mils thick are useful. In some applications, a thin foam

ferred, polyether types may also be used. Thermoset- layer may be used largely because there is no further

ting polyurethane adhesives may also be used, such as S advantage to a thicker layer and the thin layer would be

hydroxyl terminated hexanediol adipate polyester more economic.

cross-linked with about 4% of 4,4'-diphenyl methane It is preferred that the foam layer should be relatively

diisocyanate, which is preferably halogenated to im- stiff so that it does not readily compress under pressure,

prove its flame retardancy. This has the dual advantages that the insulating charac

10 teristic of the foam is retained when the foam layer is

An extruded polyester sheet about 2 J-3 mils thick is under pressure. This is particularly important since the

also a preferred adhesive. It is positioned between the orthopedic device is usually "pressed" against the body

central plastic sheet and the fabric layer and the materi- when it is formed. A relatively stiff foam layer is also an

als heated to about 350° F at a pressure of 1-2 psi to affix advantage in that it provides more accurate positioning

the fabric to the central plastic member. 15 and minimizes the amount of permissible movement of

Alternate but less preferred adhesives include the the body portion against which the orthopedic device is

acrylates, such as polyethyl acrylate, polybutyl aery- applied. The foam layer comprises a cellular structure

late, and polyethylhexyl acrylate; and a polyvinyl ace- having a great many pores in the plastic material. The

tate homopolymer and a copolymer of ethylene and foam may be of a closed pore construction or of an

vinyl acetate. The adhesive may also be blends of the 20 interconnected (open) pore construction, or a combina

foregoing. tion of both as is the usual instance. The relative stiff

The adhesive may be coated as a thin layer on the ness of the foam is preferably controlled by the selection

central plastic member and the fabric layer positioned of polymer constituents which produce a relatively stiff

on the adhesive, usually with the application of pres- foam.

sure. This will usually result in the adhesive penetrating 25 When the orthopedic device is heated sufficiently so

into the fabric layer. With a combination of a suffi- that it will remain soft for several minutes during which

ciently thin adhesive layer and sufficient pressure dur- it is shaped and formed, the plastic sheet member is

ing application, there may be some direct contact of usually heated to a temperature well above 200° F and

some of the fabric with the central plastic member is often heated to temperatures of at least 300° F and

The fabric, particularly when woven, may be par- 30 sometimes up to as much as about 350°-375° F. The tially or wholly impregnated with a plastic adhesive insulating foam layer must remain stable at the temperabefore being applied to the central plastic layer. The ture to which the orthopedic device is heated. If the preferred insulating fabric layers are partially impreg- foam layer is not stable at these temperatures, the cellunated, with the impregnating plastic being applied from lar structure would collapse as a consequence of viscous one surface to a depth of between about 0.1 mil and 7 35 flow, particularly when pressure is applied. Since demils and preferably between about 0.05 and 5 mils. This struction of the cellular structure would impair the results in a thin coating on the surface of the fabric, insulating characteristics of the foam and also the cushwhich is applied hot (or heated after application) and ioning characteristics of the foam, those foams which affixes the impregnated fabric to the central plastic are stable at above 200° F are preferred and those foams member. 40 which are stable at temperatures as high as at least 300°

The fabric layer may also be bonded to the plastic F are particularly preferred,

member by fusing, i.e., heating until the plastic is vis- It is preferred that the foam layer should not support

cous, at a temperature above about 325° F, and then combustion, i.e., not burn, or that it should have at least

contacting the fabric with pressure so that the surface of as good flame-retardant characteristics as the plastic

the plastic partially impregnates the fabric and upon 45 sheet member which is preferably a polyvinyl chloride

cooling is bonded thereto. composition. It is preferred that the foam layer should

The insulating layer may also be a plastic foam layer. not support a flame in the absence of an external flame. The foam layer provides sufficient insulation so that the The preferred materials for use as the foamed layer outer surface of the foam layer may contact the person are those which are (i) fire-retardant and (ii) stable at without severe discomfort while the plastic sheet mem- 50 temperatures up to about 200° F, and preferably up to ber is still soft and usually at a temperature substantially about 325° F. The foam materials that meet these charin excess of about 120-130° F. The insulating foam layer acteristics are thermosetting materials, or if they are may also function to cushion the portion of the person thermoplastic, very high temperature thermoplastics, against which the orthopedic device is applied. The foam should also be sufficiently flexible so that it

Since foam layers may be produced having substan- 55 may be bent during forming, and is preferably resistant

tially differing insulating characteristics and since the to perspiration and washing, and even dry cleaning,

amount of padding desired varies in different applica- The following are the preferred materials for forming

tions, the thickness of the foam layer may vary from as the foam layer:

little as about 10 mils up to about 300 mils. For most (1) Polyolefin foams such as prepared from polyethservice applications in which some cushioning is desired 60 ylene, cross-linked polyethylene and polypropylene, and/or is not detrimental, foam layers having a thick- Characteristics of polyethylene foams are disclosed in ness of between about 125-250 mils are preferred. Even the Journal of Cellular Plastics, January, 1969, at pages thicker layers, e.g., up to about 500 mils, may be useful 46-50, which disclosure is incorporated herein by referto pad a portion of an orthopedic device which will ence. Particularly preferred are fire retardant polyolefin contact a boney portion of the person, particularly 65 foams, such as fire retardant polyethylene. A useful when pressure may be applied by this boney portion method for fire retarding polyethylene and other polyagainst the orthopedic device. In some applications in olefins is to incorporate into the polymer fire retardant which very precise positioning of the body portion additives such as the Diels-Alder adducts of a hex