CA2173967A1 - Orthopedic casts - Google Patents

Abstract

Heat-recoverable orthopedic casts include a support which is maintained in an elastically deformed condition by a casting polymer, e.g. a polycaprolactone (PCL) or a side chain crystallizable polymer having a relatively low melting point. The cast is placed around the limb and is then heated. The casting polymer softens and the cast recovers around the limb. A liner is preferably placed between the cast and the limb, especially when the casting polymer is PCL or has a comparable or higher melting point. For high strength casts, the support is preferably an open-mesh knitted fabric which, when fully relaxed, contains at most 300 holes per inch2 (at most 45 holes per cm2). Such a fabric, when it is extensible to a maximum of 15 to 40 %, is also useful as casting tape which comprises a curable polymer casting composition, e.g. a water-curable polyurethane prepolymer. As illustrated in Figures 1 and 2, a stockinette liner (2) is preferably placed between the cast (1) and the limb as a thermal barrier. A reinforcing component may be used to strengthen the recovered cast. Suitable reinforcing components include (A) polyurethane precursors which are applied to the cast before or after recovery, and are polymerized during or after recovery, and (B) thermoplastic materials which are applied hot to the recovered cast. Casts made in this way can be divided to make splints which can be easily removed and replaced.

Description

ORTHOPEDIC CASTS

CROSS-RE~ERENCE TO RELATED APPLICATIONS

This application is a co~ AI;on-in-part of, and claims priority under the Tnt~rn~tional Convention from, copending, co.~ -ol-ly ~c~i n~l U.S. Patent Application Serial No. 08/150,683 filed November 9, 1993, by Larson, Bitler, Greene, and Taft (Docket No. 9218-2US) and is also a con~ ;on-in-part of copen-ling, co~ only nçd U.S. Patent Application Serial No. 08/092,351, filed July 14, 1993, by Stewart, Yoon, Larson, Ross~, Greene, Kamp and Schmitt (Docket No. 9218.1), each of which is a co..l;-~ ioll-in-part of Patent Application Serial No. 07/875,776 filed April 29, 1992, by Stewart, Larson and Yoon, now ~b~n~oneA (Docket No. 9218). This application is also related to Il,t~ aLional Application No. PCT/US93/03962 filed April 28, 1993, cl~imin~ priority from U.S. Serial No. 07/875,776 (Docket No. 9218.1-PCT). The 15 disclosure of each of those four applications is inc~l~,ul~t~d herein by reference.

RAcKGRouND OF THE INVENTION
This invention relates to orthopedic casts.
It is well known to make orthopedic casts, splints, ~iU~)Ul ~i, braces, shields, sheets, tapes, wound covers, and like orthopedic devices (all of which are referred to herein simply as "casts") from calcined gypsum (Plaster of Paris), from a polymer which is formed into shape while hot and hardens on cooling, or from a prepolymer which is formed into shape 25 and then ~oly. . .~ . ;7P~l in situ, e.g. a polyule~ e prepolymer which is hardened by water.
The term "casting co...l o~;l;on" is used herein to denote a polymeric cul~o~iLion which can be f~med into shape around a substrate (l~f~.lc;l to herein simply as a limb) and then ha~ ,ncd by ch~ l reaction or by cooling. Known casting culllposiLions can comprise a single polymer or a llfL~Lul~, of two or more polymers, and can contain additional ingredients such as ill~ lC fill-o,rs,~n~ can be ~oçi~te~ with a flexible support, which may have some elasticity, for example a fabric or a foam sheet. Reference may be made for example to US Patent Nos. 3,692,023 (Phillips), 3,728,206 (Buese), 3,809,600 (Larson), 4,019,505 (War~nan), 4,105,025 (Wang), 4,193,295 (Gruber), 4,231,356 (Usukura), 4,273,115 (Holland), 4,326,509 (Usukura), 4,404,333 (Watanabe), 4,427,002 (Baron), 4,433,680 (Yoon), 4,502,479 (Garwood), 4,770,299 (Parker), 4,473,671 (Green), 4,483,333 (War~nan), 4,609,578 (Reed), 4,627,424 (Baron), 4,643,909 (l~mmerer)~
4,661,535 (Borroff), 4,668,563 (Buese), 4,784,123 (Robeson), 4,912,174 (Grouiller), WO9S/13039 ' ' ' 2 1 73967 PCI/US94/13007 4,937,145 (Dull), 4,946,726 (Sandvig), 4,951,656 (Gorka), 4,984,566 (Sekine), 5,014,403 (Buese), and 5,027,804 (Forsyth), Eul~ean Patent Publication Nos. 0086686, 0110860, 0169037, 0338815 and 0358451, and PCT Publication Nos. WO 90/14060 and 91/09909. The ~ o~.e of each of those (iOC...,,f ~ is inco,~ul~lcd herein by reference.

All the known rn~.th~l~ of making casts require excessive time, skill and care for good results. Prepolymers offer advantages over Plaster of Paris, but the use of water is messy and incc,l,~ e nient, and L~ucnlly ~csults in nnt1fxir~hle wetting of bandages and cast linings. Thermoplastic cc""~osilions avoid the use of water, but they have not so far 10 proved s~ti~f~t~ry in use. When using casts which include an elastic support, the practice has been to stretch the cast as it is w,~ed around the patient; this leads to variable results, with excessive and/or illsurr~cient ~l~S~ulc, even when very skillfully applied.

The related U.S. application Nos. 08/092,351 and 07/875,776 and International Application No. PCI/US93/03962 (none of which had been published at the priority date of No~cl"l~el 9, 1993 cl~imeci by this Tnt~rn~tion~l appli~tio~) describe novel casts, novel ~ plastic casting compo~ition~, and novel measures for obtaining improved results with ILcl,~lastic casting c~,l"l,osilions in g~nr~l In p,-cr~,l,cd embo li. ,.el~ls~
these related applications describe novel heat-~hrink~ble casts comprising a support which is held in an el~cti~lly ~ ,l.;hcd state by a ll.cl"loplastic casting com~osilion, and the app!i~tion of such a cast by placing it around a patient, and then heating it in situ, preferably by means of hot air, thus soÇt~,llillg the casting com~osilion and permitting the cast to shrink low~.ls the patient.
SUM~RY QF T~IE INVENTION
In the further development of heat-recoverable casts as described in the relatedapplications, we have discovered, in accol.lallce with a first aspect of the present invention, that if a flexible interior m.o.mber (referred to herein as a liner) is placed between the patient and the cast while the heat-recoverable "~..ohe. is being heated, it provides a thermal barrier which increases the ...~x;.~ lelllpf ~IIIIG which the casting composition can reach during the application of the cast, and thus broadens the range of compositions which can be used wilLoul danger of h~rrning the patient~ For example, we have 3s s~lcces~fully used casting col~osilions CO~ g polycaprolactone (PCL), even though PCL melts above the Il~ lulll h-~ dh~re which can be t--le~t~A by human patients.
The p~sence of the liner also incl~,ases the reliability with which a satisfactory cast can be ` 2173967 ~l~cd. These benefits are particularly a~a-cnt when the liner inclll~les paddingm~t~risll which is com~ ,sed during recovery of the cast.

We have also discovered, in acco~-ce with a second aspect of the present 5 invention, that the p,u~,.Lies of a heat-recovered cast (whether or not it includes a liner as ~çs~ibe~l above) can be further improved by providing a flexible l~,;nfc,l-;h~g con~olle"t on at least part of the cast and treating the c~ on~n~, during and/or after recovery of the cast, to make the com~nenl relatively rigid. The flexible cc"lll)onent can be present on the heat-recoverable cast, in which case it plef~l~bly does not subst~nti~lly impede 0 recovery of the cast. ~ltern~tively or ~ lition~lly, the flexible ccu~ll,o"ent can be applied to the cast after it has been recovered. The flexible com~one.lt is preferably a prepolymer which is poly..-~ . ;7A on the cast. The flexible colll~)ollent can also be a thermoplastic casting composition which (a) is applied hot to the outside of the recovered cast, or (b) is applied cold to the outside of the recovered cast and is then heated in place. For example, 15 the flexible Co",pol,~,l,L can be a second heat-recoverable cast. When a flexible cc,lll~)onent is used in this way, the physical l~up~ ies and the appearance of the ~lni~hecl colll~osite cast depend on both the heat-recovered colll~ollcllt and the hardened flexible colll~one-lt. Indeed, the heat-recovered cast can serve prim~rily as a mold for the flexible col~one.lt and make a relatively small contribution to the physical ~ ies of the20 fini~he-l composite cast.

We have also discovered, in accc,nl~nce with a third aspect of the present invention, that when the support is a knitted fabric compri~ing at least one çl~tic~lly eYt~-nsible yarn, l,ler~lably an e~ ",.~ yarn, and at least one relatively inextensible 25 yarn, ~l~Ç~,lably a fiberglass or other high SL~ glll yarn, the size of the holes in the fabric has an Ll~l)ul~t effect on the ease with which the cast can be recovered and the strength of the recovered cast. For many types of cast, Ih~,ler(,l~" especially casts which are l~~il~d to have high strength, it is ~l~,r. ll~d to use a fabric which has a relatively large mesh such that the fabric (in a fully relaxed state) has at most 300 holes per inch2 (at most 30 45 holes per cm2). When a cast is made by heating a heat-recoverable cast comprising an el~tic~lly derolll,ed support and a heat-soft~ hl-q casting co.ll~osilion, it is usually I~S~i11 r, in order for the cast to have ~deqn~te strength, for the cast to have more than one ll-~hless of the support. In principle, this can be achieved by recovering a single cast compri~ing m-lltiple layers of the support, or by sllcces~ive recovery of two or more 3s casts, one on top of the other, each of the casts cont~inin~ one or more supports. In pr~tice, it is more cc, .~,nienl to use a single cast which is a l~min~te of two or more supports, each m~int~inç~l in a stretched con-lition by the solid casting composition, because the cast can be pre~emhled at a m~nllf~ctllring site and because multiple steps, one after the other, are not required. On the other hand, the smaller thelU~ of layers in a cast, the easier it is to l~CO . e, the cast. In our earlier work, as ~i~close 3 in Applir~tion No. PCT/US93/03962, we found that when making a high strength cast, the best col~l~lllise was to use a two-layer cast (i.e. a cast made by assembling a l~min~t~ of two layers of heat-~hrinl~hle fabIic/polyrner), and to apply a first two-layer cast around the !imb, and then to apply a second two-layer cast around the recovered first cast. This procedure, and the res~lting casts, show many improvements 10 over the previously available techniques. However, we have now found that by increasing the open area of the support fabric, yet further improvements can be obtained, especially when making a high strength cast. For exarnple, a three-layer cast (i.e. a cast ma~e by l~min~ting three layers of heat-~hrink~hle fabric/polymer) can be effectively recovered around a limb in a time which is not subst~nti~lly longer than the time needed to recover a two-layer cast and a great deal shorter than the time needed to recover two two-layer casts previously employed, and provides a fini~h~A cast of co,ll~dble strength.

We have also discovered, in accor~ce with a fourth aspect of this invention, that after ~hrinking down a heat-shrink~hle cast Cc~ illg a support which is held in an 20 el~tic~lly ~ ch~l state by a th~noplastic casting composition, the recovered cast can be co~ d into a removable splint by dividing it along one or more lines so that it can be removed from the limb, and secnring one or more f~teners, e.g. straps, to the cast so that, after the cast has been removed from the limb (e.g. so that the limb can be inspected by a doctor), it can be re-placed around the limb and secured in position. The cast is 25 preferably divided along a single line and then has snffirient flexibility to be opened up and removed from the limb. In many cases, the shrunk cast can be easily cut by means of a pair of shears. The creation of a closely fitting and removable splint in this way provides great advantages over the techniques now available.

We have also discovered, in accol~ance with a fifth aspect of this invention, that the open mesh fabrics used in the third aspect of the invention, particularly when they have a l~laXilllUIll elastic eYt~n~ihility of 15 to 40%, preferably 20 to 35%, are also useful in casting tapes which are ~ll.,tchcd as they are applied, the fabric being coated with a curable prepolymer composition, e.g. a water-curable polyurethane precursor, which is 35 treated with a curing agent just before, or during, application of the casting tape. The term ~ WO 9S/13039 2 1 7 3 9 6 7 PCT/US94/13007 "curing agent" is used herein to include chemi~l curing agent and electromagnetic or other ion which will cure the prepolymer.

In the casts used in this invention which comprise a l~ h~te of two or more S ~u~yClLS, each ,.lh;..l~infA in a ~LI~,Lched condition by the casting col~yosiLion~ the layers are preferably seF~rnts from each other except for s--ffi~ent ~ cl..-.f nt to prevent their relative displ~em~nt during h~ntlling~ especi~lly when the cast is placed around a limb.
Such attachment can be provided, for example, by a strip of hot melt adhesive which extends through the layers.

The invention in~ hl-lss yl~lucls and processes which make use of the various aspects of the invention, incl~l~ling c(j...hii~liQnc of any two, or three, or all four, of the first, second, third and fourth aspects of the invention, as well as combinations thereof with one or more other features disclosed in the related applic~tioll c or in the prior 15 doculllenl~ incorporated herein by lerc.Gnce.

The heat-recoverable articles used in the present invention are generally heat-shrink~hle, and the ~Uy~l~ therein col-c*Jondillgly are gentorally el~ti~lly stretched.
The invention is, ~ "er~,c, chiefly descrihed by reference to such articles.

A first yrer~,llcd emhodiment of the present invention is an ollhoyedic cast which compri~es (1) a heat-chrink~hle main lll~lllbel which colnrri~es (a) an el~ct~ lly ~Ll~,Lclled support, and (b) a casting com~o~iLion which collllll;ces a casting polymer having a tr~n~ition point Ts, which contacts the support and m~int~in.c it in an el~ctic~lly stretched con-lition, and which, when the cast is heated to a t~,lll~.dtul~, above Ts after it has been placed around a limb, softens and permits ~hrink~ of the heat-shrinkable member towards the limb, and

(2) a liner which is secured to the inside of the main member and which, when the cast is heated after it has been placed around a limb, provides a thermal balrier b~,lwe~;n the limb and at least part of the main member.

WO 9S/13039 ~ I ~ . 2 1 7 3 9 6 7 PCT/US94113007 ~

The term "transition point" is used herein to denote either a crystalline melting point (Tm) or a glass tr~n.~itic)n point (Tg). The term "soften" is used herein to denote softening of the casting polylll~l as it undergoes crystalline melting or as it passes through a glass transition.
s A second ~l~r~,~ clllbo~ nt of this invention is an orthopedic cast which comr~es (1) a heat-~hrink~ble main . ~ rGI as defined in the first ~lcrcll~,d embodiment of the invention, and (2) a flexible lGillrul.;il~g COlll~l~.~t which is provided on at least a part of the main member and which can be subjected to a ~ t~"~ which will reduce its flexibility.

The cast optionally includes a liner as required by the first plGr~,llGd embodiment of the invention.
A third ~ Ç~,IlGd embodiment of the invention is a heat-~hrink~ble article which(1) is suitable for use as an orthopedic cast or can be converted into an article suitable for use as an orthopedic cast;
(2) comprises (a) a knitted fabric support which (i) is in an el~tic~lly ~ ,t~;hcd condition, (ii) cc-mpri~es at least one e~ ti~ ly ~llc~Lcd yarn and at least one relatively inexten~ible. yarn, and (iii) when on its own in a fully relaxed state, has at most 300 holes per inch2 (at most 45 holes per cm2); and (b) a solid casting composition which (i) comrri.~es a casting polymer having a tr~n~itiQn point, Ts, which is above 40C, and (ii) GOl.~ L` the support and ...~ .c it in the el~tic~lly ~llG~hed condition, but does not fill the holes of the ~iU~)Ul ~, ~
and

(3) when heated above Ts in the absence of any lG~Ll~lilll, shrinks so that at least one rlim~.n~ion of the article declcases from a first value x to a second value y which is at rnost O.9~x, said shrink~ge being due at least in part to elastic ~hrink~ge of the el~cti~lly ~ ~hed yarn.

~ WO95/13039 21 73967 PCT/US94/13007 A fourth ~,Ç~ d embo~ of this invention is a heat-shrinkable article which is ~uilable for use as an olll,~edic cast in conj~ ;on with a liner in accc,r~lce with the first aspect of the invention, or which can be converted into such a cast, and which S cc~ s (a) an çlzt~ti~z~lly ~lletclled support, and (b) a casting co~ silion which (i) comrri~es a casting polymer having a i~n point Ts, which is higher than can be tolerated by a patient in the absence of the liner, e.g. at least 55C, optionally at least 60C, e.g. 55 to 85C or 55 to 65C, preferably polycapr~k~r~to~, (ii) contacts the support and ~ ;nli-;n~ it in an ek~cti~Stlly ~ tcl,~ condition, and (iii) when the cast is heated to a t~ pGl~lUl~ above Ts after it has been placed around a limb, softens and permits shrinkage of the heat-shrinkable member towards the limb.

A fifth pl~Gr~l,~l embo lim~nt of the invention is a method of forming orthopedic casts around a limb, which method comprises (A) placing around the lirnb an article accor~ g to the first, second or third ~l~,Ç~.l~ embo lim~nt of the invention which, when in position around the limb, has a closed cross-section (as defined below); and (B) heating the article so as to soften the casting cc.~ osi~ion and cause ~hrinkz~ge of the heat-shrinkzthle aTticle towards the limb.

When the article in~ (les a flexible, l~.r~,l.;i,~g co~ nt, the method includes 2s ~ubje~,~i,lg the lcillrc~l~;u~g COlll~)OnGIll to a ~ -t which reduces its flexibility.

The term "closed cross-section" is used herein to denote an article which, when viewed in cross section~ sllbst~zmtiz~lly çnc~oses an open area co..~ g the limb and has a C~ illuous or sllbst~z~ntiz~lly continllon~ l,e,iphe.y such that ~hrin~z~ge of the article 30 CC",Çolll~s it to the general shape of the limb (around a liner and/or pz~ np~ if present).
Thus the article is preferably in the form of a tube.

A sixth ~l~,r~ d c.l~bo~ of the invention is a method of forming an orthopedic cast around a limb, which method comprises 3s (A) placing around the limb an orthopedic cast which has a closed cross-section and which comprises a heat-~hrinkz~hle main lll~,mb~,l which comprises (a) an e.l~tic~lly ~I-elclled support, and (b) a casting cc"llposilion which contacts the support and m~int~ins it in an ~l~ctir~1ly ~llet~;h~d con-lition;
(B) heating the ~1 ll.ul.~c cast so as to soften the casting composition and cause .chrink~e of the heat-shrinl~hle ,~ llb~r ~w~uds the limb; and (C) ~ubj~;ling a flexible l~,inrol~ g col"~u,lcnl on at least part of the main member tu a ~ t which reduces its flexibility, said lle~ t being carried out during step (B), or after step (B), or both.

lo A seventh ~r~ led embo limPnt of the invention is method of forming an orthopedic cast around a limb, which method comprises (A) placing around the limb an orthopedic cast which has a closed cross-section and which comprises a heat-shrin~hle main member which comprises (a) an el~ti~lly ~ lched support, and (b) a casting composition which conlacls the support and m~int~in~ it in an el~ti~lly ~ tclled con~lition;
(B) placing a liner between the cast and the limb; and (C) heating the orthopedic cast so as to soften the casting composition and cause ~hrink~e of the heat-shrink~ble ,~ember towards the limb.

In this emborlim~nt of the invention, the liner can be secured to the cast (as in the first ~-~fe.led emb~limPnt) or can be placed around the limb before the cast.

An eighth ~l~,Çe.l~d ell,bodi"ænl of the invention is a method of making an orthopedic cast according to the second ~rGrGll~d emboflimPnt of the invention, which method comprises (A) providing an el~ti~lly stretchable ~uppc,-l, (B) contacting the support, while it is el~cti~lly stretched, with a casting composition which comlllises a casting polymer having a transition point Ts and which is at a telll~l~lulG above Ts;
(C) cooling the casting cc,ll~o~ilion to a lGUIPG1~tI11G below Ts to produce a heat-~hrink~hle main mGlllbel wh .~h~ the casting co"l~ûsilion m~int~ins the support in an çl:~;ti~:~lly :~LI`G`l~hed con-lhion; and (D) providing on the main lllGIll~- a flexible lGinrol~;illg component which canbe ~ubje~;led to a l~ lrlll which will reduce its flexibility.

WO 9S/13039 2 1 7 3 9 b 7 PCT/US94/13007 In this m~thod, the hot casting cc ll,l)o~.ilion is preferably applied to the support while it is ~l~ctic~lly .lletched, e.g. b~ween rollers or over a form. However, it is also possible to apply the casting cc..i.po~;l;on to the support while the support is in its relaxed state, and then to stretch the coated support, with heating before, during or after the ~ c~ g The 5 l~,;nÇol.;ing co~ enl can be provided at any con~enient stage. For example, it can be placed on the support before or after the support is el~ti~ y stretched; it can be applied before or after the casting co~ osilion, or be a part of the casting composition; it can be provided on all or on select~A part(s) of the main member, inch~-ling parts which are not conlA~ d by the casting composition; and it can be present as a continl~o~l~ or in~~ le.~l 10 coating or as a st~alalG, e.g. a self-sup~olling, film. The support can be a sheet or a tape, but in the final product is preferably of closed cross-section, particularly a tube, thus providing a cast of closed cross-section which can if desired be modified by cutting, e.g.
to a desired shape or to provide a cast of open cross-section. ~lt~rn~tively, the support can be a sheet or a tape which is formed into a cast of closed cross-section at any 15 convenient stage of the process. For example, a heat-recoverable sheet or tape can be wrapped around a form and the outer end secured to the wlalJ~ed material beneath it. The ~ ;nÇ~ g cc,lll~nenl can be provided on the sheet or tape before it is wrapped, or as it is wrapped, or after it has been wla~ed.

A ninth ~lGr~,~lGd embo~liment of the invention is a method of making a removable splint which comrri~es (A) placing around the limb an orthopedic cast which has a closed cross-section and which com~i.ces a heat-shrink~ble main l~ be. which comprises (a) an el~ti~lly sll~,t~;l ed support, and 2s (b) a casting col~posilion which COlll~;lS the support and ~ i"~ it in an cti~ ly ~llGlcll~,d co~tlitil~n;
(B) heating the orthopedic cast so as to soften the casting composition and cause shrinkage of the heat-shrinkable m~mber tOwalds the limb;
(C) after the cast has cooled, dividing it along one or more lines so that it can be removed from the limb; and (D) secl ring f~ to the cast so that the cast, after it has been removed from the limb, can be replaced and secured around the limb.

The f~ten~.rs are typically straps which are secured to the cast by means of, for example, 35 a hot melt adhesive, preferably through a patch which co.~ es a fabric support and a ~; 21 73967 WO 9!i/13039 PCT/US94/13007 hot melt adhesive and which is sewn to the strap; the hot melt adhesive is preferably the same as the casting polymer.

A ten~ ~lGr~l~l embo~lim~nt is a removable splint which comprises S (1) a flexible polymeric cast which is divided along at least one line so it can be placed over and removed from a limb, said cast comprising a fabric support and thcllllu~lastic polymer cont~cting the support, and (2) f~ten.-,rs which can be used to secure the cast around a lirnb.

0 An eleventh ~,~r~ ,d embotlim~q-nt of the invention is an article which is suitable for use as an or~opedic casting tape and which compri~es (a) a knitted fabric support which (i) c~ es at least one çl~tir~lly extensible yarn and at least one relatively ine~ct.on~ible yarn (ii) when on its own in a fully relaxed state, has at most 300 holes per inch2 (at most 45 holes per cm2) and can be el~ctic~lly extended in a lengthwise direction to an elastic limit at which its length is b~,lween 1.15 times and 1.4 times its fully relaxed length, and (b) a polymeric casting co-"~o~iLion which contacts the support and which compri~es a curable ~,~;u,~" for a polymer.

A twelfth y,er~,~d embodim~ont of the invention is a method of forming an orthopedic cast around a limb which cc.. . ~ es (A) Wld~ g around the limb a casting tape accol.lillg to the eleventh preferred embo lim~ont of the invention while the casting colllposilion is in a state which permits elastic e~hon~ion of the support, and (B) treating the casting composition so that, after the casting tape has been wl~ed around the limb, the co,llposiLion hardens to form a relatively rigid cast.
BRlEF DESC~I~IION OF THE DRAWING
The invention is illustr~t~ in the acccll,p~lying drawings, in which:
Figure 1 is a dia~,.. ,-.. -~lic lon~ l cross-section of a cast according to the first ~ ;Ç~,ll~l embodiment of the invention, Figure 2 is a transverse cross-section on line II-II of Figure 1, and ~ WO9S/13039 2 1 7 3 9 67 PCT/US94/13007 Figure 3 is a plan view of a fl~ttf~ne~l heat-recoverable main member.

7~ETAILED DESCRIPIION OF THE INVEN~ON
S Definitions. Abbreviations and Measu~
In this specifi~tion, parts, amoulll~. and ~~ f s are by weight. Tell-p~ l~tul~,s are in C. ~Sole~ r weights are weight average mnl-clll~r weights e~ ssed in Daltons and are clct~ f'~ by gel ~ f l ;nn cl~o,.lal~ hy (GPC) in tetrahydluru.an (THF).
First ~rder transition points (often GÇ~d to as mf ltin~ points), glass tr~nC~itinn points, andheatsoffusionare-l~ t~-~ Il;llf'~ byaDirrG.~.~tialSc~nningCalc, ime~ (DSC) usingthe second heat cycle and a heating rate of 10C/minute. The sor~ g point, Tm~ for crystalline polymers is the peak of the DSC curve. (~yst~lli7~tion le,ll~el~tures are flf,te~ n;l~f~ by a DSC at a cooling rate of 10C/minute.
The "power" of a m~teri~l is defined as the force in pounds required to stretch a 1 inch (2.54 cm) wide sample of the material to twice its original length. Melt Index values are lllea~u,~l by ASTM D1238 (1ll~1;1;~1). Tensile modulus values are c~lc~ te~laccording to ASTM D638 after testing the m~tf ri~l by ASTM D1708 at a crosshead speed of 1 inchtminute (2.54 cm/minute). Strength values given herein are the tensile modulus of the m~t~ri~l (psi) multiplied by the thir~ sc of the mzlt~ri~l (inch). Strength values for casts above Tm are lllea;,ul~d after heating the m~t~ri~l to (Tm +10)C and allowing it to equilibrate at that ~,~ t~, for 5 Ill;ll~ s~ Strength values for molded casts are measured at 25C after heating the cast to at least (Tm +10)C, allowing the cast to recover ~,vithout any ~ l, cooling it to 25C and allowing the cast to equilibrate at 25C for 1 hour. Air flow perm~hility (AFP) values given herein are measured as follows. An air gun is secured in a jig, and an ~ne.~OIl Irlr~ iS placed in a lGÇel~l,ce position at the center of the air stream at a distance of 5 inch (12.7 cm) from the tip of the gun. The gun is adjusted so that the air is cold and the air flow recorded by the a"~ e~ is about 1700 ft/min (570 m/min). A flat sample of the heat-recoverable ,l~t;ll,bel or the liner (or a collG~nding sample -- see below) in the shape of a circle 2 inch (5.1 cm) in ~ meter, or a larger s~mple, is placed across the air flow at right angles to the air flow, at a distance of S inch (13 cm) from the tip of the gun. The air flow is l~,cc,nled by the ~ l l lo,--eter at - three dirrGl~n~ spots within about 0.5 inch (1.2 cm) of the lerelGnce position, and is averaged. The AFP of the cast is the average air flow, e,~ ssed as a percentage of the air flow without the cast. Since the sample must be flat, and the heat-recoverable member, both before and after molding, is usually not flat, it is usually n~ess~ry to measure AFP

wo 9S/13039 2 1 7 3 9 6 7 PCT/US94/13007 ~

values on cu~ onding samples, i.e. on sheets obtained by fl~ttening out a portion of the cast, taking care not to change its pc)lu~ y, or on sheets which are flat but which have otherwise been pl~,d in the same way as the heat-lGco~e.able ~ er. For example, after ..~ g the A~P of an unused sample using cold air, the air gun can be adjusted to s provide hot air which will effect recovery of the sample, and the A~P of the recovered sample can be ll~asul~

Crush strengths are llleasul~d on an Instron 1122 tensile tester by placing the product ~l~b~n the plates of a crushing jig and forcing the plates together at room t~ lul~.

Castin~ Polymers Firt to Tenth Embo~ e.~ls The casting cc,~ o~.itions used in the first to tenth em~lim-o.nt~ of this invention contain a casting polymer having a ~r~n~ition point Ts, preferably a crystalline melting point (Tm)~ of at least 40C, particularly at least 45C, especi~lly at least 48C, to ensure that the cast does not soften under normal al-llos~h~,lic contlition~. Ts should also be such that the casting polylll~. will soften and permit recovery at l~ ,.alulGs which do not cause distress to human patients. When the cast in~hlcles a liner which acts as a thermal barrier to the heat applied to the cast to cause its recovery, Ts can be for example as high as 85C, but is preferably not more t'nan 70C. When no such liner is present, Ts is preferably no more than 60C, particularly no more than 55C. Softening preferably takes place over a range of less than 20C, particularly less than 15C, especially less than 10C, more espe~i~lly less than 5C. If the casting polymer is a polyolefin, it preferably consists esse.)l;~lly of a single tactic form, i.e. is wholly atactic or synrliot~ti~ or isotactic, so that its melting point is sharp. It is ~lcrt.~,d that l~har~n~g should take place Mpidly on cooling from above Ts to below Ts, so that the patient does not have to remain still for an e~t~n-l.oA time while the cast hardens; we have found that eYcell~nt results are obtained in practice if, when the cast is heated above Ts and then cooled to (Ts - 10)C at a rate of 10C/min, the casting polymer rehardens in not more than 2 min-~tes, preferably not more than 1 minute, after it has cooled to Ts .

When a liner is used, casting polymers having Ts's above 55C, e.g.
polycaprolactone-based coll~osi~iuns, can be used will~ut causing distress to the patient, and are often ~l~L.l~d bccause of their ready availability. Suitable polycaprolactone-Wo sstl3039 Pcrtuss4/l3007 based casting polymers include co~ osilions disclosed in the do~;umell~s incorporated herein by l~Ç~ ce. The polycaprolactone preferably has a Tm of about 55C to about 60C, and a molec~ r weight of 20,000 to 80,000, particularly 30,000 to 40,000.
Exarnples of such polycaprnl~tones which are co....-~ -.;ially available include the product 5 sold by Solvay Interox Ch~ mi~ (W~rrington, Great Britain) under the trade narne CAPA-640, which has a l~)Ul b d molec~ r weight of about 37,000 and a Tm of about 57C, and the product sold by Union Carbide (Danbury, C'o.-nr,cl;~ u~, USA) under the trade name Tone 767E, which has a reported molecular weight of about 40,000 and a Tm of about 55C. Polycaprol~cton-os of molecul~r weight less than 40,000 are generally 10 ~ d because of their lower melt viscosity.

Also useful as casting polyrners in the present invention, particularly when the heat-recoverable cast does not include a liner, are crystalline polymers in which the crystallinity results exclusively or predominantly from side chains which are ~tt~-~he~l to the polymer 5 backbone. Such polymers are often l~re~lc;d to as side chain cryst~lli7~ble polymers, or SCC's, and are described in detail in the three copenclin~ applications referred to above and in Int~..lational Patent Application No. PCT/US92/08508 filed October 6, 1992 (Docket No.
9213.2-PCI) and copending co.u--.ol-ly ~sign~l US Application Serial No. 08/048,280 (I)ocket No. 9213.2) filed April 14, 1993, the disclosures of which are incorporated herein 20 by reference and to which reference may be made for further details. The SCC polymers can be mixed with other polymers, including for example polycaprolactone, ethylene/vinyl acetate copolymers, ethylene/butyl acrylate copolyrners and ethylene/methyl acrylate copolymers.
The molecular weight of the SCC casting polymer is generally more than ~,000, and 25 when it is the sole polymeric ingredient of the casting con~o~ilion is preferably at least 50,000, for example 60,000 to 300,000, particularly at least 100,000, for example 140,00() to 200,000. When the casting polymer is a block copolymer co"~ i--g SCC blocks, its molecular weight is preferably more than 25,000, especially more than 75,000, with the molec~ r weight of each SCC block preferably being 2,500 to 20,000.
The casting polymer can be cro~linkeA by r~ tiQn or ch~o-mir~l cros~linking m~tho~ls known to those skilled in the art. Radiation cros~linking can be effected, fûr example, by an el~ll~,n beam or Cobalt 60 r~ tion. C~h~mi~l cros~linking can be effected, for example, by means of peroxides or silanes, by ionic cro~slinking, or with the 35 aid of multifunctional agents.

WO 95tl3039 ~,", i 2 1 7 3 9 6 7 PCT/US94/13007 F.l~.venth and Twelfth Embc! liments The clc~ l- and twelfth embo~ of the invention use casting compositions which comrri~e a curable polymeric c<.~ osilion, preferably a water-curable polyurethane S ~ ul~r, for example a co l~o~iLion as ~lesç~ibeA in one of the do~ nl~ incc,.~!uldled he~Gin by lGr~.lc~.

Castin~ Compositions 0 The casting cc,l"l~osilion can contain, in addition to the casting polymer, one or more ~-lrlition~l polymers and/or one or more non-polymeric ing~die"~, e.g. h~ anic fillers, plasticizers, antioxidants, pr~ces~ing aids, and pigm~nt~, for example carbon black, graphite, glass fibers, Kevlar fibers, silica, I;l~ni~ dioxide, talc, m~gnçsium call,onale and calcium c~l~nate. For further details, reference may be made to the five col)e--rli~-g applications referred to above.

Supports First to Tenth Embodi..~ s The SUP~O1~ used in the first to tenth embo 1;., .~ of the present invention arepreferably el~ctir ~lly d~Çullllable. The support preferably has, in the main member before it is recovered, an open ~llu ;lUlG which assists in the heat transfer between dirf.,l~,nl parts of the main lllemb~l, and which, in the fini~he~l cast, remains s~lfficje-ntly porous to ensure that the 2s support has a high moisture vapor ~n~mi~ion rate (MVTR) and thus does not prevent the limb from "bl~,allling". Particularly for making high strength casts, e.g. load-bearing casts.
casts around broken bones, etc., we have obtained eYrell-ont results using a fabric support which cn,nt~in.~ at most 300 holes per inch2 (at most 45 holes per cm2), particularly S0 to 25, especially 80 to 150, holes per inch2 (8 to 40, preferably 12 to 25, holes per cm2).
30 However, for cases where less strength is adequate or is desired, e.g. around sprained limbs, soft tissue injnries~ carpal tunnel injuries, gree-n~tir~ fractures, and fractures which are mostly healed, ~U~ having a greater number of holes, e.g. 300 to 600 holes per inch2 (45 to 90 holes per cm2) may be ~ler~l~d. ~Gr~l~d ~U~O1~ are knitted fabrics (preferably warp-knitted, especially Raschel knitted, fabrics) which compri~e one or more elastomeric yarns 35 and one or more high strength yarns, particularly glass fiber yarns. The yarns in the fabric preferably consist e sse~ lly of continuous fil~ ont~ which are free from permanent crimps and have a .li~."~ t~-~ of 0.007 to 0.02 inch (0.018 to 0.05 cm). The support may be isotropic or have dasticity or other pl~Lies which vary directionally. Preferably the support can be W O 95/13039 . . P C T~US94/13007 stretched el~ti~lly in at least one direction by at least 25%, preferably at least 50%, e.g. 50 to æ5%, based on the cc,llG~onding ~l;...f l~ion of the support in its unstretched state, i.e. to at least 1.25 times, preferably at least 1.5 times, e.g. 1.5 to 3.25 times, its original en~ion The power of the fabric is preferably 0.1 to 2.0 lbfimch (18 to 360 g/cm), and the fabric may contain for eY~mple 5 to 40%, preferably 10 to 25 %, of the extensible yarn to provide suitable recovery forces.
Fl~venth and Twelfth Embc~

The knitted support fabrics used in the first to tenth embo~lim~nt~ are also useful in the eleventh and twelfth embo~l;...r.,.l~i providing that they are ~ ti~lly extensible to an elastic limit of 15 to 40%, preferably 20 to 35 % . If the extensibility is too low, the tape will not cc,nÇ~ to the limb as the tape is wrapped; if the exten.~ibility is too high, there is a danger that the tape will be wrapped too tightly around the limb so that the hardened cast 15 will cause distress to the patient.

Heat-Recoverable Main Members The casts used in this invention, before they are recovered around a substrate, 20 preferably comprise a heat-recoverable main ll~lllb~r whose heat-recoverability results at least in part from the presence of an el~ u...~ . ;c support which is ~ ed in an elastically deformed (usually ~l~.,~hed) condition by the casting composition, and which recovers Ic,w~.ls an undeformed confi~ ion when the casting polymer is softened by he~tin~
The casts will often comprise two layers, each layer comprising a support m~int~inecl in an 25 el~ti~lly ~ cl,ed con~lition by a casting coll,~osilioll. The layers may be the same or dirr~ ~nt, and are optionally bonded together.

The available recovery of the main lll~ lllbc. will depend on the extent of the der~ n put into the support. Preferably the main .~.r,~..h,-, if heated in the absence of 30 any restraint~ will recover so that at least one dim~n~ion thereof decreases from a first value x to a second value y, where y is at most 0.95x, particularly at most 0.75x. It is generally ~ -ecess~. y fory to be less than 0.4x, and in most cases y is more than 0.45x.
The strength (inclll-ling the crush strength) of the recovered main member depends not only on the support and the casting polymer and the ~iimP.n~ n~ and amounts thereof, but 35 also on the extent of the recovery and the heating used. It is often desirable to continue the heating for a short while after recovery of the main member, e.g. for another 1 to 3 ...;..."rs, in order to con~olitl~te the cast.

wogsll303s 2 1 73967 PCT/US94/13007 The recovery forces in the main ~ bel should be sl~ffi~iPnt to ensure adequate conr,. ~.~A-~ce of the cast to the limb, but not so high as to ~m~ge the patient, or cause pain, or reduce blood flow. The power of the cast, in the direction of recovery, is, s t~ ,rol~, preferably 0.1 to 2.0 lbfinch (18 to 360 g/cm).
We have found that the casts are much easier to apply, without ove. I ,e~t;ng which can cause distress to the patient or the ortho~di~.L, if the main l~-r-..b~, has, before recovery, an open SLlu~;Lul~ which permits rapid and ullir~lll heating of the casting colll~osiLion, especi~lly when using a hot air gun to heat the cast. Thus the main member, before recovery, preferably contains a plurality of apertures having an average area of at least 0.01 cm2, preferably at least 0.02 cm2; on the other hand, the apertures should not be so large as to permit the limb to become o~e.lleAI~l Especially when the cast includes a liner, the size of the a~ ul~s is preferably less than 0.12 cm2, e.g. 0.03 to 0.12 cm2, particularly 0.03 to 0.09 cm2. When no liner is present, the size of the apertures is preferably less than 0.08 cm2, particularly less than 0.06 cm2. In the heat-recoverable article, the number of holes (which is of course ~lepenrl~ont on the number of holes in the relaxed support and the extent to which the support has been stretched) is preferably 20 to 100, particularly 30 to 60, holes per inch2 (3 to 15, particularly 5 to 10, holes per cm2) when making high strength casts, but may be higher, e.g. 100 to 170 holes per inch2 (15 to 25 holes per cm2) when making relatively low strength products. The size and number of the a~llul~,s are preferably such that over ~.ub..~ ial areas of the heat-recoverable member, particularly over the whole of the casting polymer, heating the cast with a hot air gun causes a difference in le~ tule, between the inside and the outside of the heat-2s recoverable . . .- . .~, at any particular point, of not more than 15C. Preferably the main el has, before recovery, an air flow permeability (AFP) of at least 5%, more preferably at least 10%, particularly at least 20%, but less than 60% when a liner is present, and less than 45% when no liner is present, more preferably less than 35%. The AFP of the heat-recovered Illellll)er, after recovery, is preferably at least 1%, more 30 preferably at least 2~o, particularly at least 5%, especially at least 8%, but is preferably less than 25%, more preferably less than 20%, particularly less than 15%, especially less than 10%.
It is desirable that the cast should become relatively inflexible in a short period 35 after mnlfling is complete. Preferably, therefore, the casting con~osiLion, as it cools, ch~ng~s ~m a mold~ble com~osilioll to a relatively stiff coln~o~i~ion over a l~lnp~l~ture range of less than 10C, particularly less than 5C, and preferably does so in less than 5 . . .; . .ules, particularly less than 2 ~ es The casting polymer need not recover all of its crystallinity in order for the casting CC,lllpoSilion to become relatively inflexible. In this sl~;l;r~l;on, the polymer can be leg~lcd as having cooled to a crystalline relatively infl~ible m~t~ri~l if its crystallinity is at least 0.5 X, where X is the crystallinity of the S polymer after it has been cooled from above Tm to (Tm-10)C and ...~ d at (Tm -10)C for four cryst~lli7~tion half lives.
The main llh,l-b~,. preferably has a closed cross-section which is in ~ ately the desired final shape, but sufficiently oversize to allow the cast to be placed around the 10 limb. However, to assist in fitting a cast to a limb, and/or to assist in its later removal, the cast may c~mrri~e at least one cla~LulllGlic cc"lll,onel-t which is free of the casting collJposiLion and is el~ti~lly deformable before or after (preferably both before and after) the cast has been fitted around the substrate. The ela~lulllelic colllpone.lt can be a lon,~ l colll~on~lt which extends over part or all of the length of the cast, or a radial 5 component which extends around part or all of the cil~;ulllrcl~i.lce of the cast. For further details, lefe.GIlce should be made to US application Serial No. 08/092,351, incorporated b~
ler~ ce herein. In ~AAition, it should be understood that the invention also includes heat-recoverable articles, e.g. tapes, which can be used to make heat-recoverable casts of closed cross-section, e.g. by wl~ g around a form to make a pr~rc,lllled cast or by wrapping 20 around the limb itself.
Pre-shaped casts may have a wide variety of shapes, including for example a cylinder for use as a finger splint, a bent cylinder to suTround an ankle, knee or elbow, or a glove to surround part or all of a hand.
2s ion of Castin~ Co,llposilions and Heat-Recoverable Main Members The casting compositions used in this invention can be ~ d by procedures well known in the art, and can be formed or applied to ~u~ ls by procedures well known in the 30 art, e.g. as solutions in organic solvents which are removed by drying, or as molten composition~, e.g. by melt ~ usion onto the support or by hot l~min~tion. When the ccJ~ osi~n is applied as a ~nelt, it preferably has a viscosity at 95C and/or at the le.l~ tUl~i at which it is applied, of 700 to 7,000 poise, preferably 1500 to 7000 poise.
The casting cc,llll)osilion is preferably applied to the ~LIetched support and then cooled while 35 ..~ ;n~ the support in the stretched condition. However, it is also possible to apply the casting cc,l~ll)osi~ion to the non-deformed support, and then to stretch the composite, e.g.
over a mandrel or other form, while the casting composition is at a temperature above Ts, ~' t followed by cooling with the support in its ~ cd condition. Casts having similar shape but dirr~ellt strengths can readily be ~-Gp~.,d by wrapping a cooled, coated, stretched tape over a form twice, or three times, or more than three times. 'T~n~r~lly at least one ~imen~ion of the support is stretched by 40 to 150% of its ullsL-~lcllcd length (i.e. to 1.4 to 2.5 times its unsll~,tclled length), preferably 60 to 150%, for example 100 to 140%, of its un~LI~,tched length. After the coll.~o~ ion has been applied to a support, it may be desirable to heat it, at a ~ n~ , above Ts~ optionally with yl~,s~ " to ensure that it fully penetrates the support The casting cc Illl,o~ilion is preferably applied in a way and in amount such that it does not block the holes in the support, 2nd preferably so that the average area of the holes in 10 the cooled, coated, heat-recoverable product is at least 0.5 times, particularly at least 0.7 times, especially at least 0.8 times, the area of the holes in the ~ tch~d support before it is coated. For this purpose, it may be desirable to blow air through the casting composition to ensure that the open ..1l u~;Lul~ of a porous support is not filled up by the casting polymer.
The casting ccn--~osiLion generally provides 40 to 60% by weight of the heat-recoverable 5 article. In many cases it is desirable that the heat-recoverable main member should be sllffi~çntly flexible to be fl~ttened, e.g. for ease of storage or to enable it to be cut to a desired shape.

When a liner is present, as is ~ Gr~"-cd, the liner provides a thermal barrier between the limb and at least part, preferably all, of the heat-recoverable main member while the main ~m'oe~ is being recovered. Since the liner remains in place between the recovered cast and the limb, it must have s~ti~f~tory pç~,lLies (e.g. permeability to water vapor) for this use.
2s In the cast before it is recovered, the liner is preferably el~tir~lly deforrned so that it fits snugly around the limb after the cast has been recovered. We have obtained excellent results with a liner which is el:~etif~ ly dt;Çoll--able and which has a plurality of a~l~ s through its thirlfn~s5 such that it has an air flow permeability (in the under~ ed state) of less than 25%.
When, as is ~ ~r~--,d, the main mP.mb-o.r has a plurality of a~, ~ S through its thickness, so 30 that it can be more readily recovered by means of a stream of hot air, the liner preferably has an air flow pennP~hility of less than 0.75 times the air flow perme~bility of the main member.

The liner preferably compri~eS a stocL inette fabric, i.e. an el~tic~lly deformable circular knit fabric, preferably a circular rib knit fabric. The stoc~inette may for example 3s COI~ e a natural or synthetic polymeric yarn, e.g. a cotton or other cellulosic ya~n, or a polyester, ~oly~ullide or polyp.~ylene yarn. The ~.locL ;~.clle preferably has a fully recovered .li~"h te~ which enables it to fit snugly around the limb to which the cast is applied. Suitable st~L ;n~ ; fabrics are well known in the art, ~or example for covering a limb before forming a cast around the limb. In the present invention, by contrA~t, the liner is secured to the main " ~ ., .h~ . so that it provides a thermal barrier bCL~ the limb and the heat-recoverable main ....... ~ - The liner;s preferably secured to the main ~ bel by means of end sections which 5 pass around the ends of the main ~ bl,l and are secured to the outside of the main member, preferably by means of elastic forces ~,e~ A by der.)~ g the liner.

While the heat-recoverable rnain llff ~ iS being heated in order to recover it, the ends of the liner are preferably unfolded so that they cover the parts of the patient a~ e1lt l0 to the area to be covered by the cast, thus providing a thermal barrier in these areas as well as Im~ e~ the cast.

The liner preferably cc ~ ,lises a p~lcling material which is cc,m~r~ssed between the limb and heat-recovered main ll,elll~l. Particularly when such p~-lrling material is 15 present, a ulliçullll p,~,s~u,~ en the cast and the limb can readily be achieved.
Suitable p~ 1ing n~t~ri~1~ are typically non-woven fabrics of cotton (or other cellulosic) or synthetic, e.g. acrylic or polyester, fibers, and are well known to those skilled in the art. Foamed polymers can also be used as p~ltling m~t~ri~1 lUAt~iAl~ which combine an tit~s~lly der(.. I l ~Able fabric and p~Adtlin~ m~t~.ri~1 are ccm~ ;ially available and can be 20 used in this invention, including for example the product sold by Landec Corporahon under the trade name C~ 1il-el, which has a knitted outer ply a~n~ g polyester and Lycra fibers and a terry loop inner ply also cc,.u;~ g polyester and Lycra fibers; the product sold by Smith and Nephew Casting under the trade name ProTouch One-Step,which is a cotton/sp~n~lex ~l~L i"~lle having adhesively bonded to it polyester p~ ling 25 which permits the ~I~L i,.~,llt~ to expand without tearing the pAd~ling; the product sold by Balfour Health Care under the trade name Terry Rolls, which is an acrylic/spandex rib knit ~ L ;~el~e with acrylic loops on one surface only; and the ~r~luc~ sold by Knit Rite under the trade name Cast-Rite, which is a thick acrylic/spandex circular knit stockinette fleeced on one surface only.
Rei..rc.l~;in~ Cvmyollen~

- In preferred embo~ of the invention, a flexible leh~ g c(",lpollellt is provided on at least part of the heat-recoverable lll~,.llb~,l, and is treated to reduce its 35 fleYibi1ity while the main . . .~ - is being recovered, and/or after the main member has beenrecovered. The ~ l...f -~ will generally not affect the main ~ h~l, but the . ~ 21 73967 invention includes lGih~fc,l~ g c.,ll,yoilellL~ and l ~ which have s~;y~. nte effects on the le;,-rcl~;ing CC111YOI1GIII and on the Illrlllbel and those which act jointly on the ~IÇul~ g colll~oll~nt and the main ...- ..be- to strçng~h~n the fini~hecl cast.
s The flexible colllyonent can be applied to the main member at any apylc,y,iate stage, for eY~ , 'e before the main rll~.llb~. is s~t ;l~ed at all, after it has been ~LIGlcllGd but before the casting polymer has been applied to it, while it is heat-recoverable (either as a heat-recoverable tape or as an ar~icle made by wl~ypillg a heat-recoverable tape around a form), while it is being heat-recovered, or after it has been heat-recovered. There may be 0 more than one ,~infc,l.;ing collryollent~ applied to the same or different parts of the main m-ombçr, applied at the same or dirr~.~.-t stages, and c~n~i~ting of the same or different m~t~ri~l~

When the leh~rw.;illg cc,m~nen~ is applied to the main m~mber before the main member is recovered, it must not prevent, and preferably does not subst~nti~lly change, recovery of the main ",t;lllber. Preferably it compri~es a prepolymer (i.e. a mixture of mnnomfA~r~ and/or oligomers which can be poly....,. ;7f ~), and which can be treated, during and/or after recovery of the main lllel~ ,., to effect polymçri7~tion The prepolymer can for e~ lc be applied as such or as part of a liquid composition, for example a solution 20 of the prepolymer in a solvent which is at least partially e~ayul~ted before and/or during recovery of the main llle.llbel. The prepolymer can also be applied in association with a substrate, e.g. a knitte~, woven or non-woven fabric or netting, a polymeric film, or lçul-;ing fibers, provided that the ~LIb~Llat~ does not prevent recovery of the main mc.lll)e.. The prepolymer can for example be Suyyul ~d by, e.g. impregn~tecl into, an 25 elastic support which is ~ chcd over the heat-recoverable main n~lnbel and which recovers lJwa.ds a relaxed condition during heat-recovery of the main member. The lllrln to effect poly...~ on can for çY~mple be to apply (e.g. spray) a chemiç~lreagent, preferably water, and optionally a catalyst, to the prepolymer, or to expose the prepolymer to a catalyst and/or radiation which will effect polym~ri7~tion thereof. When 30 applied after recovery of the main - Irl I ~be~, the water or other cl~r~ l reagent can also serve to cool the heat-recovered cast. Par~cularly yl~,r~ ,d prepolymers are polyurethane polymers which can be polym~i7~ by the addition of water, and which typically are reaction Il~ S of at least one polyol with a molar excess of at least one polyisocyanate so that the reaction ll~ ul~ conlains free iso~;ya~alt; groups, generally 4 to 30%, 35 preferably at least 5%, particularly at least 8%, free iso.;yallale groups. Suitable polyui~lhalle prepolymers are disclosed, for example, in the docu,llcnls incorporated ~ Wo 95/13039 2 1 7 3 9 6 7 PCT/USg4/13007 herein by lcrcl~,nce, and often include a~l-lition~l ingredients such as stabilizers (e.g.
benzoyl chlori~e), anti foaming agents (e.g. poly~iloY~nes), viscosity mo~ifiers, and catalysts (e.g. tertiary amines). We have fou~id that casts with higher strengths are often ob~h,cd when the polymPri7~tion of the ~,~oly-llcl takes place at the same time as the 5 recovery of the main n F~ h~- . The heating which causes recovery of the main member U~ ases the rate of l~oly. . IF - ;7~1 ;on and reduces the visco~ily of the polymPri7~tiQn mix, which results in less fr~min~, as CO~ ,d to a se~alale polymPri7~tion step afterlec~, . e.~ of the m-~in mPmhPr When the flexible con~ollcnt is part of the heat-recoverable cast, it is important to store the cast under conditions which prevent the flexible CC ~ OnG1II from becoming inflexible, for e~ )lc in a moisture-L..~G....eable envelope.

When the .~,i-~ing co.nponellt is applied to the cast after it has recovered, it is not 15 n~ces~ry that the lGi,lfol.;ing co,ll~llellt be one which does not impede recovery. Thus the flexible CO11J~One11l can for example comrri~e a prepolymer as described above, and the prepolymer can optionally be coated onto or otherwise associated with a substrate, e.g. a knitte~l, woven or non-woven fabric or netting, a polymeric film, or reinforcing fibers, which, if present before recovery of the cast, would impede recovery of the cast. The 20 ~ub~ G can for eY~mI~le be knitted or woven from glass fiber yarns, polypropylene yarns, or elastic yarns, or colllbh~alions thereof. When the l-,i,lÇc,l~ g collll~ol ent is applied to the recovered cast, it is also possible for it to comprise a thermoplastic m~teri~l, preferably a ll,~,l.l~p!astic polymer, optionally coated onto or otherwise associated with a substrate, e.g.
as just described for a ~ olylllGr. Suitable ~ .ll-~lastic rn~teri~l~ include those already 2s known for use as casting m~teri~l~, in~ in~ those disclosed in the documents incorporated herein by l~,Çt;~.,ce. A pl~f~l~d m~t~ori~l co...~ cs polycaprolactone or a derivative thereof, optionally m~xed with one or more other polymers. The Illel...~lastic m~ttori~l can be r,~l and applied hot to the recovered cast, or laid onto, preferably wrapped around, the recovered cast and then heated in situ.
- The l~ c,l.;ing cc lll~ullenl can also be a second heat-recoverable cast, for c~ le a heat-recoverable cast according to the first ~l~f~ ,d embodiment of the present invention but wilLoul the liner, or a heat-recoverable cast according to the second or third ~l~,f~ ,d em~oflimtont of the present invention, or a heat-recoverable cast as disclosed in US Serial Nos. 07/875,776 and 08/092,351 and Tnttom~tion~l Application No.
PCI~/US93/03962 incorporated by reference herein. The second heat-shrinkable cast re~ro~ s all or sçlecteA parts of the cast which has already been applied. It can also be used to improve the a~e~ ce of the cast and/or to cover the ends of a liner which have been folded back over the ends of the recovered main ...~...hc- For eY~mple the l~lÇC~ g C~ t can be a little shorter than the applied cast, so that it covers the s GA~ ies of the folded ends of the liner, but leaves a margin, e.g. of 0.5 to 2 inch.

Preferably at least a part of the main member lies between the rei--rol~;ing cc,~ ol~e.ll and the limb to which the cast is applied. The main m~mber can then act as a barrier ~l.. ~n the limb and the l~iinr~,lcil,g cu,ll~ol~n~, for ~Y~n~ple to provide a thermal 0 barrier belw~GIl the limb and a hot th~ ~lastic ,~i,.ro,-;"lg colll~n~llt, or to prevent or reduce contact b~L-. ~n the limb (and any b~nd~s or dressings on the limb), and water or other reagent applied to harden a prepolymer.

When a l~"h~rcl.;i,lg colll~ne.lt is used, the lGi~ÇC"~;i"g COlll~unenl iS selected so 15 as to çnh~nce the physical and/or esthetic ylu~llies of the main ,1,~ . Preferably the p,~s~nce of the ~.nro,.;ing coml). "ent results in a fini~herl cast whose crush strength is at least 1.5 times, particularly at least 2 times, the crush strength of a fini~hPA cast which is i(iPnti~l, and has been treated i~lenti~lly, except that it does not include the l~iinfol~;ing CC~ en~. ~deed the l~inr~,lcil~g CO"~pO"~ t can supply almost any ~,lu~llion of the 20 crush strength of the fini~hs~l cast. For example, the heat-soft~n~hle casting polymer can be used in an amount which is sufficient to ,. .~ the support in its el~ctir~lly deformed state but which makes little contribution to the strength of the fini~h~l cast. For example, the finished cast can have a crush strength which is more than 5 times, even more than 10 times, the crush strength of a fini~h-oA cast which is iden~ ~1 except that it does not include 25 the l~ rul~;ing cc,ll-~onent. In this e~ t of the invention, the main member can act principally as a form which, after it has molded to the shape of the limb, distributes the forces of the ~ lfol~ g co,l-~onent, particularly when the l~ir,rul.;i"g com~nent is ~up~ull~d on a sheet or tape, e.g. an elastic sheet or tape, which is wrapped around the recovered main - ~ - - bf , and thus helps to ensure that no undue ~ ,S:iUl~ iS exerted on the 30 limb.

P~eff rring now to the drawings, Figures 1 and 2 are .li~.,,"",~ longit~--lin~l and s~ e cross-sections of a cast according to the invention which includes a heat-recoverable main mf mber 1 and a padded ~lOCLilleLlt; liner 2. The main mt;.llb~l 35 compri~es multiple wraps (usually 2 or 3) of the support, which is held in an el~tic~lly derc~lllled condition by the casting colll~o~ilion. The ends of the liner 2 are folded back Wo 95/13039 2 1 7 3 9 6 7 PCT/US94113007 over the ends of the rnain ~ b~,l. Figure 3 is a dia~, I~l"~tic plan view of a flattened heat-recoverable main l-~embel l which is suitable for use as an arm cast. A main n~lllbe in the form of a ~;ylindel has been fl~tton~A and then cut so as to l~l~luce a thumb hole 11 Of ~ te- b at an axial ~ t~nce a from one corner of the memher. In ~ lition, starting at 5 a radial rli~t~nre c fr~m the same corner and ending at an axial ~ re d below the ol,~osile corner, the end of the cylinder has been cut off along line 12, so that the member will co"rullll better to the palmer creases of the hand.

The invention is ~ by the following Examples.

E~fAMPLES
Examples 1-15 In FY~mrles 1 to 15, the support was made from an el~ctir-~lly extensible fabric15 which is available from Carolina Narrow Fabrics (Winston Salem, North Carolina, USA). The fabric is a three bar knitted warp fabric with ECDE 75 1/0 Z glass fiber yarn in the first and second bars and a natural rubber yarn in the third bar. It has a density (u~ cd) of 800 + 100 g/m2 and will return to subst~nti~lly its originAl length if clled by up to about 2.5 times its ~lrigin~l length.

The liner is made from a padded stor~inette having a fl~tt~ne~l width of about 9 cm (i.e. a ~1;A~ f I of about 5.75 cm) which is availabie from Smith and Nephew Casting (Menomol1ee Falls, Wisconsill, USA) under the trade name Protouch One-Step and which is a cotton/sp~n-leY stoc~;,.e~e with an adhesively bonded polyester padding of low 2s density which can be ~Ir~ ed by the stn~ el~e without tearing.

The polyu,~,lLalle prepolymer coml,osiliol s A and B co~ A the ingredients and alllUUnlS thereof (in grams) set out in the table below.

In~redients _ B
Isonate 143L 200 63 Pluracol P1010 188 19 Poly G 36-232 - 13.5 13-,.1~yl chloride 0.2 0.1 Poly~ Lhyl siloxane0.5 0.3 Isonate 143L is available from Dow (~h~mi~l (Midland, Michigan, USA) and is 10 methylene diphel~ylene diisocyanate and oligomers thereof. Pluracol P1010 is available from BASF Pt~r~ e Ch~mic~l~ (r~si~y, New Jersey, USA) and is polyethylene glycol. Poly G 36-232 is available from Olin Ch~mic~l~ (Cheshire, Connecticut, USA) and is a polyether polyol. DABCO is available from Air ~xlu~;L~ and Chemi~
(Allel,lowll, Pennsylvania, USA) and is triethylene ~ mine; it is a catalyst for the poly.. ~ ;o.- of Isonate 143LandPluracolP1010. AnalternativecatalystisDMDEE
(2,2' dil~ holino listhyl ether), which is available from Texaco Chemicals (Houston, Texas, USA). 13e~lzoyl chlori~le is an inhibitor. Polydilllclllyl siloxane is an antifoaming agent which is available from Dow Corning (Midland, Michigan, USA) or from Huls ~m~ric~ (Bristol, Pennsylvania, USA).

F~ )lC 1 The casting cclll~osilion used in Example 1 was a blend of about 80% of an SCC
polymer having a Tm of about 50C and about 20% of an ethylene/vinyl acetate copolymer 2s (EVA~ which is available from duPont (Wilming~on, Delaware, USA) under the trade name Elvax 210, is reported to contain about 28% vinyl acetate and to have a softening point of about 90C. The blend has a molecular weight of about 200,000. The SCC
copolymer had a molecul~r weight of about 220,000 and contained units derived from about 68% of dodecyl acrylate (C22A), about 4% acrylic acid (AA), and about 28% of styrene (STY). The blend was made by the following procedure. C22A (68 parts), STY
(28 parts), AA (4 parts) and ~ ec~ns thiol (0.04 parts) were mixed. 20 parts of the ul~, were heated to about 120C. The ~ i.,;.,g 80 parts were mixed with t-amyl peroxy-2-ethyl hexanoate (0.5 part) and added over 90 ~ s, m~int~ining the reaction , at 120C. The te. . ,~ , was raised to 140C over a period of about 45 111;1~ " while adding t-amyl peroxy benzoate (0.5 part). The Le~ Gldtule was at 140C for a further 2 hours. EVA (25 parts) and butylated hydroxytoluene (0.3 part) were then added, and the ~ ulc ~ P~ at 40C for a further 1-2 hours, with stirring- The blend was then cooled.

The casting cc,l"~o~ilion was heated to a l~ ~.alulG of about 100C and was thens melt coated onto a length of the support fabric, about 11.4 inch (28.8 cm) long and about 12 inch (30 cm) wide. The coated fabric was ...~;n.l ~;..~1 at a t~ ...e of about 100C
for about 4 hours to ensure that the support was thoroughly i~ ~l by the casting co~ osilioll, and was then cooled. The coated fabric was l~,healt;d by means of a hot air gun to a t~ alul~, of about 90C, ~ilet ;hcd to about 2.5 times its origin~l length, and lo cooled in the ~ lched state. The ~ ,t~hcd fabric was about 28.5 inch (about 72 cm) long and about 12 inch (36 cm) wide, had an open ~llu ;lulc with a plurality of al~ellulGs each having an area of about 0.02 cm2, and had an AFP of about 15.5%. The cooled, sll~,t~,Lcd, coated fabric was wrapped three times around a metal mandrel having a c~.iull~el~ ce of about 9.5 inch (about 24 cm), i.e. a li~m~Pter of about 3 inch (about 7 15 cm), and the outer wrapped end was secured to the layer below with a polyamide hot melt adhesive.

The composite structure was removed from the mandrel. It had an AFP of about 7%. It was fl~t~enP~ and then cut to a shape as shown in Figure 3 (in which the outer edges of 20 the portions removed are shown by the dotted lines) and having .~ cions a, b, c and d a~ ox;...~1y as follows: a, 4 cm; b, 3.8 cm; c, 3 cm; and d, 2 cm.

The cc,mpo~ile ~I1UCIU1G was l.,~ cd to a generally cyli~ 1 shape and a length of the liner fabric was placed inside it. The liner fabric was about 15 inch (38 cm) long, 2s and had a hole about 0.4 inch (1 cm) in ~ t~ - punched in it, the center of the hole being about 2.4 inch (about 6 cm) from one end. The centers of the holes in the heat-able main llh ~llh.,( and the liner were a~lv~ill~lGly ~li nPd, and the ends of theliner were then ~ tched radially and folded back over the ends of the main member.

The resul~ing orthopedic cast could be fl~ P~1 for storage purposes, and then - restored to a genP~lly cylin~lric~l shape before use.

The cast (after being restored to a gene~lly cylin(1ric~1 shape) was slipped over a person's hand, wrist and fc l~,a~ , with the thumb through the holes in the liner and main 35 . . .~ ~, and with the angled end parallel to the palmer creases of the hand. The folded ends of the liner were unfolded over the person's arm and hand. The heat-recoverable WO95/13039 ~ 2 1 73967 PCTJUS94/13007 ~

main m~mber was then heated with a hot air gun to soften the casting composition and cause recovery- of the cast around the wrist and ru,.,allll. This took about 2-5 minlltes The the liner p,~ d the patient from being bumed by the hot air and the heated cast.
After the cast had cooled, the ends of the liner were folded back over the cast, thus S p~ltling its edges.

Fx~mple 2 Example 1 was ,~eat~d except that the casting cc Illpo~ilion was a polycaprolactone comllosilion which is available from Solvay Interox ~hemic~l~
ngt ~n, Great Britain) under the trade name CAPA 640, and which has a Tm of about 57C and a l~ d molec~ r weight of about 37,000.

The casts produced in Examples 1 and 2 had similar crush strengths (about 50 lb), 5 but the adhesion bel~en the layers was better in Example 2 than in Fl~mrle 1. We have found that if the amount of EVA used in Example 1 is increased to about 40%, or if an EVA of higher mole~ r weight (e.g. Elvax 240) is used, the adhesion between the layers improves.

20 F.xample 3 A cooled, ~llet~;h~l, coated fabric was made as in Example 1. A length of the fabric about 4 inch (10 cm wide) was wla~ed twice around a metal mandrel having a cu~;ul~ nce of about 24 cm, i.e. a rli~mçter of about 7.6 cm, and the outer wrapped end 2s was secured to the layer below with a polyamide hot melt adhesive. The composite ~ll uclul~ was removed from the Il~ , placed over a second metal mandrel having a cin~u~ nce of about 19 cm, i.e. a rli~m~ter of about 6 cm, and fully shrunk down onto the second ,lla~ ,l, using a hot air gun. Its weight was about 25 g.

30 F.Y~ml?le 4 Example 3 was ,~e~lYl, and the recovered cast, still on the mandrel, was coated with about 10 g of prepolymer composition A. The coating was then sprayed with water, and as a result poly.~ ~1, with fo~ming The res--lting cooled product had a 35 subst~nti~lly greater crush strength than the product of Example 3.

wo gSl13039 2 1 7 3 9 6 7 PCT/USg4/13007 F.~ ulf S

FY~mrle 3 was repe~tç~l except that before the comrositto structure was shrunk down onto the second m~ndrel, it was coated with about 10 g of prepolymer colllposition 5 A. Just before using the heat gun to shrink the C~....pOS;~t ~LIu;lul~, the prepolymer layer was ~Jlay~d with water. Application of the hot air gun resulted in ~imlllt~n~oous ~hnink~gto of the colllposi~ u~lur~, and poly. . .~ ;on of the prepolymer. The poly. . .~ l ;on mix foamed less and had a lower viscosity during the poly.~ ion than in Ex~mrle 4. The res -lting cooled product had a ~ub~ lly greater crush strength than the product of 10 Example 4.

Example 6 Example 3 was repeated except that the second mandrel had a ch-;u~ ce of 15 about 14 cm, i.e. a tli~meter of about 4.5 cm.

Fx~mIlle 7 F.Y~mple 6 was l~,~e~lled, and the recovered cast, still on the second mandrel, was 20 coated with about 10 g of prepolymer cc, ll~osilion B. The coating was then sprayed with water, and as a result polym~ri7~, with fo~ming Ei$hll~ c 8 FY~mrle 6 was l-_pe~r~l except that before the cc,~ osilt; structure was shrunk down onto the second mandrel, it was coated with about 10 g of prepolymer IlliX~Ule composition B. Just before using the heat gun to shrink the co-l-posiLe structure, the prepolymer layer was ~layed with water. Application of the hot air gun resulted in ~imnl~ eous shrinkage of the co-l-~osile ~l1U~;IU1~ and poly~ ion of the prepolymer.
The polymPri7~tion mix foamed less and had a lower viscosity during the polymerization than in FY~mrle 7.

Example 9 FYAmrle 8 was repeated7 taking particular care to ensure a UlliÇol~ll coating of the prepolymer com~o~ilion.
s F Y ~ j?1e; 10 Example 6 was ~ ~l except that a film of the SCC/EVA casting cc,lll~osilion, about 0.024 inch (about 0.6 mm) thick, was placed be~ ,n the wraps of cooled, 10 ~ ,~hcd, coated fabric before the composite structure was recovered by heating.

The crush strengths of the products obtained in Examples 7-10 are shown below.

EY~mr1e No. 6 7 8 9 10 Crush Strength (lb) 1.7 15.2 14.4 26.2 8. ]

Example 1 1 The procedure of Example 1 was followed up to the stage at which the composite ~lu~;lulc was removed from the mandrel. A piece of the support fabric (19.2 x 30 cm) impregnAt~l with prepolymer colll~o~i~ion B (45% of total weight), was formed into a tube using a polyamide hot melt adhesive. The tube was ~lle~h~d and fitted over the composite structure. The reslllting assembly was placed over a mandrel (rli~m~t~r about

4.5 cm) and then heated with a hot air gun at about 70C for about 5 minlltes so that the cast recovered and conrc,lllled to the mandrel. Water was then sprayed onto the cast, causing poly.~-~.. ;,Alion of the prepolymer. The fini~h~l cast had a substantially greatér crush strength than the product of Ex~mrle 1.

Example 12 Two i(lentir~l composite structures were made by the procedure of Example 1 except that the eYr~n(l~l support fabric was 48 x 10 cm and was wrapped twice around the 24 cm mandrel. The first structure was placed over a mandrel ( liAm~ter 4.5 cm); and heated in an oven at about 70C for about S .-~ es so that it recovered. The second5 ~ll u~ was then placed over the first, and heated in an oven at about 70C for about S
les so that it recovered.

~ WO 95/13039 2 1 7 3 9 6 7 PCT/US94/13007 Exam~le 13 The ~l~Jcedul~, of Example 12 was followed except that a single composite

5 structure was ~ d and recovered.

Exatnples 14-15 The ~lvcedul~s of Ex~mrles 12 and 13, l~.~;Li.~ely, were followed, except that O the casting composition was CAPA 640 as in Example 2.

The crush strengths of the recovered casts in FY~mrles 12-15 are given in the table below.

15 Example No. 12 13 14 15 Crush Strength (lb) 50 9.6 69 26 F.xamples 16-22 FY~mrles 1~22 are :,.. i.. ;7PA in the Table below and illustrate the improved results which can be ob~ by using more open knitted fabric ~ul,~o ts. Example 16shows the results oblilincd with a knitted fabric which is not in accol~lance with the third aspect of the invention because the openings in it are too nu~ ,us and too small.

In each of F Y; - ~ ,les 16-22, an elastic knitted fabric was prepared on a three-bar Raschel knhting m~chin~, using the number of n~e llçs~mch, courses/inch and fabric wales shown in the Table. In each Example, Bar 2 was a fiberglass yarn ((1i~meter about 0.0156 inch~ available from PPG Tn~n~tries Inc. under the trade name ECDE 37 1/0(abbreviated to FG37 in the Table). In Examples 17, 19, 20 and 21, Bar 1 was the same as Bar 2. In FY~mrles 16 and 18, Bar 1 was a fiberglass yarn (tli~m~ter about 0.0106 inch) available from PPG Tn~ triçs Tnc nn~l-or the trade name ECDE 75 1/0 (abbreviated to FG75 in the Table). In each of the Ex~mrles, Bar 3 was a natural rubber monofil~mçnt yarn which had a ~i~m-o~tor of about 0.0165 inch (0.04 cm) in Example 16 (abbreviated to R60 in the Table) and about 0.019 inch (0.05 cm) in Ex~mrles 17-22 (abbreviated to R50 3s in the Table); both yarns are available from Globe Rubber Co. under the trade name GM9.
The fabric, as made and fully relaxed, was ~s~minetl to d~t.,.~ e its density, its - : 2 1 7 3 9 6 7 thic1rness, its power, and the number of holes per inch2; the results are shown in the Table.

In each of the FY5~ 1eS~ the fabric was ~lle~;hed by about 150% in the lon it~ lin~l 5 di~,clion, i.e. to about 2.5 times its f)rigin~l length (the transverse rlimf n~ion changes by less than 10%), and while ~ ,t~hf d was melt-coated with a polycaprolactone (PCL) co...pos;l;on which is available from Solvay Interox Chf mi~ rringtnn, Great Britain) under the trade name CAPA 640, and which has a Tm of about 57C and a reported molec~ r weight of about 37,000. The ~ ,t~;hed, coated fabric was,, ,~ e~l at a 0 ~ dlU~ of about 110C for a time s~fflci~o,nt to ensure that the fabric was thorQughly lcA by the PCL, and was then cooled in the ~ ,~hcd state. The number of holes per square inch, the average hole size, and the AFP, of the cooled, stretched, coated fabric were measured, and the results are shown in the Table under the heading "ready-for-use".

A first sample of each fabric was recovered 20%, and the average size of the holes and the AFP were measured. The results are shown in the Table under the he~Aing "recovered 20%".

A second sample of the coated fabric about 10 cm wide was wrapped 2, 3 or 4 times 20 (as reported in the Table) around a first metal mandrel having a c~u~ ,nce of 24 cm, and the outer wld~ed end was secured to the layer below with a polyamide hot melt adhesive.
The wld~ped fabric was removed from the first mandrel, placed over a second metal mandrel having a ch-;u~ ce of 14 cm, and then heated with a hot air gun until the PCL softened, ~ ....;Il;..g the fabric to recover against the second mandrel and causing the wrapped fabric 2s layers to bond to each other. In one part of Fy~rnrl-~ 16, a first sample of the coated stretched fabric was wld~ed twice around the first lllan&~il, and then heated and recovered around the second Illa~ l; and after the first s2mple had cooled, a second sample of coated stretched fabric was w~a~d twice around the first mandrel, removed from the first mandrel, placed over the second l,~ l and the filrst sample recovered over the second mandrel, and then 30 heated and l~ After cooling, the recovered pl~xlu~;L was removed from the second mandrel and tested for crush strength. The crush strengths are reported in the Table.

TABLE
F l~s..ol,les Barl FG75 FG37 FG75 FG37 FG37FG37 FG37 Bar 2 FG37 FG37 FG37 FG37 FG37FG37 FG37 Bar 3 R60 R50 R50 R50 R50 R50 R50 ~ee~lPsrmch 12 6 6 6 9 9 9 Course/inch 29 13 20 19 22 14 19 Fabric Wales 237 114 120 179 179 179 179 Density (g/m2) 900 570 483 712 1000800 890 Thichless (inch) 0. lOS 0.11 -- 0.1 0.090.13 0.1 Power (lb/inch) 0.55 - - - 0.57 - 0.55 AFP
(i) readyforuse 29 - - 38.6 25 25 27.7 (ii) recovered (20%) 14.5 l9.S16 14.6 12 Hole Size (cm2) (i) ready for use .016 - - .07.045 .048 .048 (ii) recovered (20%) 0.0125 - - O.OSS 0.03 0 033 0 033Holes/square inch (i) as made 440 lOS -- 170 200 126 190 (ii) ready for use 145 35 -- 56 80 48 78 % PCL 44 45 46 47 50 50 50 Crush S~ength (i) 3 wraps 29 -- 34 32 57 54 52 (ii) 2+2 wraps 54 -- -- -- -- -- --(iii) 4 wraps -- 63 48 -- -- -- --

Claims (28)

1. An article which is suitable for use as an orthopedic cast which comprises (1) a heat-shrinkable main member which comprises (a) an elastically stretched support, and (b) a casting composition which (i) comprises a casting polymer having a transition point Ts, (ii) contacts the support and maintains it in an elastically stretched condition, and (iii), when the cast is heated to a temperature above Ts after it has been placed around a limb, softens and permits shrinkage of the heat-shrinkable member towards the limb, and (2) a liner which is secured to the inside of the main member and which, when the cast is heated after it has been placed around a limb, provides a thermal barrier between the limb and at least part of the main member.

2. An article according to claim 1 wherein the liner comprises a tube of elastically stretched stockinette fabric.

3. An article according to claim 1 or 2 wherein the liner comprises a padding material which is compressed when the main member is shrunk by heating the cast after it has been placed around a limb.

4. An article according to any one of the preceding claims wherein the liner has an air flow permeability of less than 25%.

5. An article according to any one of the preceding claims wherein the heat-shrinkable main member has a plurality of apertures through its thickness, each of the apertures having an area of 0.01 to 0.12 cm2, and the liner has an air flow permeability which is less than 0.75 times the air flow permeability of the heat-shrinkable main member.

6. An article which is suitable for use as an orthopedic cast and which comprises (1) a heat-shrinkable main member which comprises (a) an elastically stretched support, and (b) a casting composition which (i) comprises a casting polymer having a transition point Ts, (ii) contacts the support and maintains it in an elastically stretched condition, and (iii), when the cast is heated to a temperature above Ts after it has been placed around a limb, softens and permits shrinkage of the heat-recoverable member towards the limb, and (2) a flexible reinforcing component which is provided on at least part of the main member and which can be subjected to a treatment which will reduce its flexibility.

7. An article according to claim 6 wherein the reinforcing component is precursor for a crosslinked polymer, preferably a water-hardenable precursor for a polyurethane.

8. A heat-shrinkable article which (1) is suitable for use as an orthopedic cast or can be converted into an article suitable for use as an orthopedic cast;
(2) comprises (a) a knitted fabric support which (i) is in an elastically streched condition, (ii) comprises at least one elastically stretched yarn and at least one relatively inextensible yarn, and (iii) when on its own in a fully relaxed state, has at most 300 holes per inch2 (at most 45 holes per cm2); and (b) a solid casting composition which (i) comprises a casting polymer having a transition point, Ts, which is above 40°C, and (ii) contacts the support and maintains it in the elastically stretched condition, but does not fill the holes of the support;
and (3) when heated above Ts in the absence of any restraint, shrinks so that at least one dimension of the article decreases from a first value x to a second value y which is at most 0.95x, said shrinkage being due at least in part to elastic shrinkage of the estically stretched yarn.

9. An article according to claim 8 wherein the support, on its own in a fully relaxed state, has 50 to 250, preferably 80 to 220, holes per inch2 (8 to 40, preferably 12 to 34, holes per cm2).

10. An article according to claim 8 or 9 which has 20 to 100, preferably 30 to 60, holes per inch2 (3 to 15, preferably 5 to 10, holes per cm2).

11. An article according to claim 8, 9 or 10 wherein the average size of the holes is 0.03 to 0.12, preferably 0.03 to 0.09, cm2.

12. A heat-shrinkable article which is suitable for use as an orthopedic cast or which can be converted into an orthopedic cast, and which comprises (a) an elastically stretched support, and (b) a casting composition which (i) comprises a casting polymer having a transition point, Ts, which is at least 55°C, (ii) contacts the support and maintains it in an elastically stretched condition, and (iii) when the cast is heated to a temperature above Ts after it has been placed around a limb, softens and permits shrinkage of the heat-shrinkable member towards the limb.

13. An article according to any one of the preceding claims wherein the casting polymer is polycaprolactone or another crystalline polymer having a melting point, Tm, from 45° to 85°C.

14. An article according to any one of the preceding claims wherein the support comprises at least one yarn composed of an elastomer and at least one high strength inextensible yarn which is substantially free from permanent crimps.

15. An article according to any one of the preceding claims wherein the support is warp-knitted, preferably on a Raschel knitting machine.

16. An article according to any one of the preceding claims which, when heated above Ts in the absence of any restraint, shrinks so that at least one dimension of the article decreases from a first value x to a second value y which is at most 0.75x, the shrinkage being due at least in part to elastic shrinkage of elastically stretched yarns in the support.

17. An article according to any one of the preceding claims which comprises a laminate of two or three supports, each maintained in an elastically stretched condition by a solid casting composition.

18. A method of forming an orthopedic cast around a limb, which method comprises(A) placing around the limb an article as claimed in any one of the preceding claims which, when in position around the limb, has a closed cross-section, and (B) heating the article so as to soften the casting composition and cause shrinkage of the article towards the limb.

19. A method according to claim 18 which includes the steps of (C) providing on at least a part of the main member a flexible reinforcing component which can be subjected to a treatment which will reduce its flexibility; and (D) subjecting the reinforcing component to a treatment which reduces its flexibility.

20. A method according to claim 19 wherein step (C) is carried out prior to step (B); step (D) is carried out simultaneously with step (B) or after step (B); and the reinforcing component is a water-hardenable polyurethane precursor.

21. A method of forming an orthopedic cast around a limb, which method comprises(A) placing around the limb an orthopedic cast which has a closed cross-section and which comprises a heat-shrinkable main member which comprises (a) an elastically stretched support, and (b) a casting composition which contacts the support and maintains it in an elastically stretched composition;
(B) heating the orthopedic cast so as to soften the casting composition and cause shrinkage of the heat-shrinkable member towards the limb;
(C) subjecting a flexible reinforcing component on at least part of the main member to a treatment which reduces its flexibility, said treatment being carried out during step (B), or after step (B), or both.

22. A method of forming an orthopedic cast around a limb, which method comprises(A) placing around the limb an orthopedic cast which has a closed cross-section and which comprises a heat-shrinkable main member which comprises (a) an elastically stretched support, and (b) a casting composition which contacts the support and maintains it in an elastically stretched condition;
(B) placing a liner between the cast and the limb; and (C) heating the orthopedic cast so as to soften the casting composition and cause shrinkage of the heat-shrinkable member towards the limb.

23. A method according to claim 22 wherein the liner is placed around the limb before the cast.

24. A method of making an orthopedic cast as defined in claim 6 or 7, which method comprises (A) providing an elastically stretchable support;
(B) contacting the support, while it is elastically stretched, with a casting composition which comprises a casting polymer having a transition point Ts and which is at a temperature above Ts;
(C) cooling the casting composition to a temperature below Ts to produce a heat-shrinkable main member wherein the casting composition maintains the support in an elastically stretched condition; and (D) providing on the main member a flexible reinforcing component which can be subjected to a treatment which will reduce its flexibility.

25. A method of making a removable splint which comprises (A) placing around the limb an orthopedic cast which has a closed cross-section and which comprises a heat-shrinkable main member which comprises (a) an elastically stretched support, and (b) a casting composition which contacts the support and maintains it in an elastically stretched condition;
(B) heating the orthopedic cast so as to soften the casting composition and cause shrinkage of the heat-shrinkable member towards the limb;
(C) after the cast has cooled, dividing it along one or more lines so that it can be removed from the limb; and (D) securing fasteners to the cast so that the cast, after it has been removed from the limb, can be replaced and secured around the limb.

26 A removable splint which comprises (1) a polymeric cast which is divided along at least one line so that it can be placed over and removed from a limb, said cast comprising a fabric support and thermoplastic polymer contacting the support, and (2) fasteners which can be used to secure the cast around a limb.

27. An article which is suitable for use as an orthopedic casting tape and whichcomprises (a) a knitted fabric support which (i) comprises at least one elastically extensible yarn and at least one relatively inextensible yarn, (ii) when on its own in a fully relaxed state, has at most 300 holes per inch2 (at most 45 holes per cm2) and can be elastically extended in a lengthwise direction to an elastic limit at which its length is between 1.15 times and 1.4 times its fully relaxed length, and (b) a polymeric casting composition which contacts the support and which comprises a curable precursor for a polymer.

28. A method of forming an orthopedic cast around a limb which comprises (A) wrapping around the limb a casting tape according to claim 27 while the casting composition is in a state which permits elastic extension of the support, and (B) treating the casting composition so that, after the casting tape has been wrapped around the limb, the composition hardens to form a relatively rigid cast.