Orthopedic casts with controlled flexibility

Details Orthopedic casts with controlled flexibility Orthopedic casts with controlled flexibility

2001-02-01

2004-01-06

Morris, Terrel (Department: 1772)

Fabric (woven, knitted, or nonwoven textile or cloth, etc.)

Coated or impregnated woven, knit, or nonwoven fabric which...

Coating or impregnation improves elasticity, bendability,...

C442S169000, C442S171000, C442S175000, C442S180000, C442S415000, C442S416000, C602S008000, C523S111000

Reexamination Certificate

active

06673727

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to novel materials for making orthopedic casts. In particular, this invention relates to urethane resin systems useful in making orthopedic casts that have levels of flexibility that can be controlled depending on specific therapeutic needs.
A variety of materials are known in the art for protecting or immobilizing arms, legs, or other body members. Casts and splints are used, for example, to protect a body part from injury, or to allow a broken bone to heal properly. Historically, such casts were made of plaster of paris. However, plaster casts have recently been largely replaced in many applications by orthopedic bandages or sheets impregnated with synthetic resin mixtures. The synthetic resins used in combination with certain knitted or woven substrates offer a number of advantages over the old plaster materials. In particular, casts made from the synthetic materials are lighter, stronger, harden more quickly, allow for better air circulation, and are not water sensitive.
Among the synthetic resin compositions used to prepare casting materials are water-activated or water-curable synthetic resin compositions, and thermoplastic resin compositions. The water-activated or water-curable synthetic resin is impregnated auto bandages or sheets, which are typically referred to as “tapes”. As with old plaster casting materials, these resin-impregnated sheets are wetted before application to the body member. The water begins the curing reaction that hardens the cast. Other compositions for casting materials use synthetic resin compositions employing different kinds of curing mechanisms, for example crosslinking through unsaturation.
Particularly preferred synthetic resins for orthopedic casts are the polyurethanes. Such resin systems comprise a water-curable mixture of an isocyanate and a hydroxy-containing compound. Casts made with such materials are disclosed in, for example, Japanese Patent Publication 54-100181, Takazawa et al., published Aug. 7, 1979; British Patent Specification 1,578,895, Straube et al., published Nov. 12, 1980; U.S. Pat. No. 4,131,114, Kirkpatrick et al., issued Dec. 26, 1978; U.S. Pat. No. 4,376,438, Straube et al., issued Mar. 15, 1983; U.S. Pat. No. 4,411,262, von Bonin, et al., issued Oct. 25, 1983, issued Feb. 28, 1984; U.S. Pat. No. 4,433,680, Yoon, issued Feb. 28, 1984; U.S. Pat. No. 4,473,671, Green, issued Sep. 25, 1984; U.S. Pat. No. 4,502,479, Garwood et al., issued Mar. 5, 1986; U.S. Pat. No. 4,609,578, Reed, issued Sep. 2, 1986; U.S. Pat. No. 4,667,661, Scholz et al., issued May 26, 1987; U.S. Pat. No. 4,774,937, Scholz et al., issued Oct. 4, 1988 and U.S. Pat. No. 4,968,542, Gasper et al., issued Nov. 6, 1990.
Such casts are typically rigid when cured, with no flexibility. As with plaster casts, such rigid urethane casts may be useful in therapeutic applications where total immobilization is desired. Non-rigid casts are also known in the art, for use in applications where some degree of movement is permissible or desired. The use of such casts for prevention of injuries (e.g., sports injuries) is described in U.S. Pat. No. 4,968,542, Gasper et al. However non-rigid casts among those known in the art may be too soft for many applications, and afford a limited range of uses unless combined with more rigid materials during the cast formation process. Moreover, such casts may also have limited durability during use, resulting in delamination where layers of the cast separate, compromising the structural integrity of the cast.
SUMMARY OF THE INVENTION
The present invention provides improved casting materials that have an optimal degree of flexibility relative to rigid and semi-rigid casting materials known in the art. Preferred compositions of this invention comprise a substrate impregnated with a water-curable resin comprising an aromatic polyisocyanate and a polyol, wherein the free NCO level of said resin is from about 6% to about 10%. Preferably the free NCO level is from about 7% to about 10%, more preferably from about 7% to about 8%.
Applicants have found that the methods and articles of this invention provide benefits versus casting compositions among those in the art. Such benefits, including enhanced ability to be used in a variety of therapeutic and preventative applications, improved usage characteristics, and improved stability of casts made using the compositions.
DETAILED DESCRIPTION
The invention provides compositions that are used to make orthopedic casts. As referred to herein, an “orthopedic cast” is a device that encloses, in whole or in part, a body member (e.g., a leg) of a human or other animal subject. Such casts may be used for the prevention of injury, or in the treatment of disorders such as broken bones. Specific compounds, compositions and other components to be used in such orthopedic casts must, accordingly, be pharmaceutically and cosmetically acceptable. As used herein, such a “pharmaceutically and cosmetically acceptable” component is one that is suitable for use with humans and/or animals without undue adverse side effects (such as toxicity, irritation, and allergic response) commensurate with a reasonable benefit/risk ratio.
Curable Resin:
The compositions of this invention comprise a water-curable resin. As referred to herein, a “water-curable resin” is a polyurethane prepolymer that is curable upon contact with water. Such contact may be to water vapor (e.g., through exposure to air), through immersion of the composition in water, or through any other means which effects sufficient exposure of the composition to water so as to initiate curing of the resin.
Curable resins of this invention comprise, and may be prepared by reacting, one or more polyisocyanates and one or more polyols. The polyisocyanate may be aliphatic, cycloaliphatic, or aromatic diisocyanates, triisocyanates, or tetraisocyanates, as well as biurets, isocyanurates, and similar oligomers of these. Examples of useful polyisocyanates include, without limitation, toluene diisocyanates (TDI), including the 2,4 and 2,6 isomers and mixtures of these isomers; diphenyhnethane diisocyanates (MDI), including the 4,4′, 2,4′, and 2,2′ isomers and mixtures of these isomers; hydrogenated diphenylmethane diisocyanates, aromatic polyisocyanates derived from phosgenation of the condensation product of aniline and formaldehyde (polymeric MDI), hexamethylene diisocyanate, isophorone diisocyanate, octamethylene diisocyanate, trimethylhexane diisocyanates, dodecamethylene diisocyanates, cyclopentane diisocyanate, cyclohexane diisocyanate, tetramethylxylene diisocyanate, and biurets, allophonates, isocyanurates, and substituted derivatives of these, such as carbodiimide-containing polyisocyanates. (As used herein, the words “include” and “including” are intended to be non-limiting, such that items that are included in a list are not to the exclusion of other like items that may be useful in the compositions and methods of this invention.) Preferred isocyanates include polymeric diphenylmethane diisocyanates (polymeric MDI's).
The polyisocyanate is reacted with at least one polyol. Examples of suitable polyols include, without limitation, polyether polyols, polyester polyols including polycaprolactone polyols, and monomeric diols and triols such as 1,6-hexanediol. Preferred polyols include polyethylene oxide and polypropylene oxide diols and triols, having a molecular weight of at least about 2,000, preferably from about 2,000 to about 4,000, more preferably from about 3,000 to about 4,000. Preferably the polyol has a hydroxyl number of from about 28 to about 56, preferably from about 28 to about 46, more preferably from about 35 to about 40. As referred to herein, the “hydroxyl number” is the number of milligrams, per gram of polyol, of potassium hydroxide having an acid neutralization capacity equal to the polyol. Preferred polyols include PPG 3025, having a molecular weight of about 3,000 and a hydroxyl number of from about 35 to about 40, sold by Lyondell Chemical Company, and QO Polym

Affiliated with

Also associated with

Rating

Orthopedic casts with controlled flexibility does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Orthopedic casts with controlled flexibility, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Orthopedic casts with controlled flexibility will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3227691