Abstract:
An orthopedic casting system that includes a cast tape having a moisture responsive resin therein, the tape being wound onto a tubular polymeric core for shipment and storage prior to use in forming an orthopedic cast. The tubular core has a wall with an inner and outer surface in a first position comprising a plurality of relatively shallow convex and concave portions that extend linearly of the core. Each of the concave portions provide a longitudinal trough along which water flows adjacent the inner wraps of the cast tape. The wall of core is flexibly resilient so that the upon application of a radial inward force on the cast tape and the core, the wall will flex to a second position in which the troughs are deepened. When the force is released the tubular core returns to substantially the first position.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention is directed to an orthopedic cast tape system, and in particular to a uniquely configured core for use with orthopedic cast tapes that improves the distribution of moisture to the cast tape wrapped around the core. 
       BACKGROUND 
       [0002]    Orthopedic cast tapes with moisture responsive resins conventionally are subjected to water to cure the resin in the tape and form the cast to treat wrist, arm, ankle and leg fractures, as well as muscle strains. Cast tapes have been supplied on cores with an outer packaging used to keep moisture away from the resin impregnated on the cast tape until time for use. Typically, a doctor, nurse, orthopedic technician or other person removes the cast tape from the packaging and, prior to application to the patient, introduces moisture to the resin by exposure to ambient conditions, or by submerging the cast tape still on the core in water. Either method has its drawbacks, in that sufficient moisture may not adequately be exposed to the maximum amount of resin prior to the onset of cure. The patient&#39;s limb is then wrapped with the tape which is then allowed to cure. This in turn may cause an irregular, or even in some cases, an ineffective cure of the tape to form the cast. 
       SUMMARY OF INVENTION 
       [0003]    The inventor has addressed the problem of irregular and inefficient cure of orthopedic casts by developing an improved orthopedic cast system, including a uniquely configured tubular core. An aspect of the invention is an orthopedic casting system with a cast tape having a moisture responsive resin therein and a tubular core. The cast tape is wound onto a tubular core for shipment and storage prior to use in forming an orthopedic cast. The tubular core is formed of a flexible polymeric material and includes a wall with an inner and outer surface. The core wall has a plurality of relatively shallow convex and concave portions that extend linearly of the core. When the cast tape is wound on a core, the concave portions provide a series of longitudinal troughs along which water flows adjacent the inner wraps of the cast tape. Further, the wall of the tubular core is flexibly resilient so that upon application of a radial inward force on the cast tape and the core, the wall will flex to a second position in which the troughs become deepened, allowing even freer flow of moisture. When the force is released, the tubular core returns to substantially its initial position. The plurality of convex and concave portions and the flexible resilience of the wall improve the distribution of moisture along the core and into the cast tape. 
         [0004]    Another aspect of the invention is the tubular core itself upon which an orthopedic cast tape is wound. The core is formed of a tubular flexible polymeric material and has a wall with an inner and outer surface. The core wall has a plurality of relatively shallow convex and concave portions that extend linearly of the core. Again when the cast tape is wound on a core, the concave portions provide a longitudinal trough along which water or moisture flows adjacent the inner wraps of the cast tape. Further, the tubular wall of the core is flexibly resilient so that upon application of a radial inward force on the cast tape and the core, the wall will flex to a second position in which the troughs are deepened. When the force is released, the tubular core returns to substantially the first position. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0005]      FIG. 1  is a perspective view of an orthopedic cast system without the packaging thereon. 
           [0006]      FIG. 2  is a front end view of the orthopedic cast system without the packaging thereon. 
           [0007]      FIG. 3  is a perspective view of a tubular core without the orthopedic cast tape wrapped thereon. 
           [0008]      FIGS. 4A and 4B  are schematic views of the end of a tubular core of the orthopedic cast system. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0009]    Certain exemplary embodiments of the present invention are described below and illustrated in the accompanying figures. The embodiments described are only for purposes of illustrating the present invention and should not be interpreted as limiting the scope of the invention, which, of course, is limited only by the claims below. Other embodiments of the invention, and certain modifications and improvements of the described embodiments, will occur to those skilled in the art, and all such alternate embodiments, modifications, and improvements are within the scope of the present invention. 
         [0010]      FIG. 1  shows an improved orthopedic casting system  5  that includes a cast tape  12  with a moisture responsive resin therein, and a tubular core  10  on which the cast tape  12  is wrapped. The casting system  5  may be stored and shipped in a sealed package (not shown) to prevent the exposure of the cast tape resin to moisture which might otherwise initiate a premature cure of the cast tape. 
         [0011]    The improved orthopedic casting system  5  may be used by an orthopedic technician, doctor, nurse or other person to treat a broken bone or muscle strain as described above. In use, the casting system  5  is first removed from the package. The core  10  with the cast tape  12  thereon is then exposed to moisture or submerged in water. The user applies some radial force, or flexes, the core  10  to help facilitate movement of the water along the core  10  and into the cast tape  12  as will be discussed in more detail below. When the adequate amount of moisture has been exposed to the cast tape and resin, the cast tape  12  is removed from the core  10  and wrapped around the wound site. The cast tape will then set or cure through the normal curing process. 
         [0012]    In exemplary embodiments, the cast tape  12  may be between 3 to 6 inches wide. The length of the core  10  would approximate the width of the cast tape  12 . However, the core  10  can be any length and can correspond to any width cast tape  12  as is needed for the particular wound or injury. 
         [0013]    The cast tapes themselves may be woven or warp knit fabrics. The fabrics may be formed from fiber that include, but are not limited to, glass, polyester, polypropylene, aramid, and polyamides. The cast tape includes a moisture curable resin impregnated thereon. For example, a conventional polyurethane-based resin is an exemplary type of resin used. 
         [0014]    The tubular core  10  is formed primarily of a polymeric material and may be extruded to an indeterminate length and cut to the requisite size for the particular orthopedic cast system to be used. The core  10  may be formed from a group of polymers selected from the group consisting of linear low density polyethylene (LLDPE), low density polyethylene (LDPE), polyethylene (PE), linear high density polyethylene (LHDPE), high density polyethylene (HDPE), and polyester. Although other polymers may be used as needed. 
         [0015]    As shown in  FIGS. 2 and 3 , the core includes a tab  25  extending inwardly from the inner surface  22  of the core  10 . The tab  25  helps wrap the cast tape  12  on the core. For example, winding machines typically include a mandrel for receiving a core  10  (without cast tape). Such mandrels include a slot that extends longitudinally along its length. The core  10  slides longitudinally onto the surface of the mandrel while the tab  25  is received by the slot. One end of the cast tape  12  is positioned on the core  10 , and as the mandrel rotates, the core  10  is driven to wrap a length of cast tape thereon. In other alternate embodiments, however, other mechanisms for securing the core onto a mandrel during winding may be used. For example, the core  10  may not have any tab  25 . In such a situation, the mandrel may be expansible to engage the inner surface of the core. 
         [0016]    Referring to  FIGS. 2 ,  3  and  4 A and  4 B, the wall  20  includes a plurality of convex portions  40  and concave portions  30  that form longitudinal troughs  45  extending linearly down the length of the core  10 . The troughs  45  form an open space between the concave portions  30  of the wall  20  and the inner wraps of the cast tape  12 . The troughs  45  allow water to more easily pass down the length of the core  10  when the cast system  5  is submerged in water. In the embodiment shown, the core  10  has between four (4) and six (6) convex portions and between four (4) and six (6) concave portions. In an exemplary embodiment, the core  10  has six (6) convex portions and six (6) concave portions. 
         [0017]    As suggested above, the core  10  may have any geometry that forms the longitudinal troughs  45  discussed, while also providing for a flexibly resilient wall  20 . Referring again to  FIG. 4A , the wall  20  includes a plurality of points  46  in the bottom of troughs  45  between adjacent convex portions  40 . The distance between two parallel lines that are tangent to the perimeter  48  of the circle subtended by the core peaks  40  and point  46  in the relaxed position, respectively, is referred to as the depth or amplitude, D 1 . In an embodiment, the amplitude (D 1 ) is no less than about 0.10 inches (0.254 cm). In an exemplary embodiment, the distance D 1  is 0.12 inches (0.304 cm). A larger amplitude (D 1 ) corresponds to deeper troughs  45  on the core and as needed, the amplitude (D 1 ) may be larger or smaller. 
         [0018]    An aspect of the core  10  is the ability to distribute water to the cast tape  12 . The relatively shallow troughs characterized by the combination of peak-to-peak distance between adjacent convex portions and the amplitude or depth of the concave portions increase the extent of water surface area to cast tape contact. This improves the distribution of water to the resin and promotes a better cure of the cast tape on the wound site. In a preferred embodiment, the peak-to-peak distance may be about 0.486 inches (1.236 cm) for a 0.93 inches (2.36 cm) diameter core. The peak-to-peak distance, however, may be about 0.25 inches or more. As described above, the amplitude D 1  is preferably greater than about 0.10 inches (0.254 cm). In a preferred embodiment, the amplitude D 1  is preferably about 0.12 inches when in the first, un-flexed position. While this particular trough profile has been found to improve water distribution along the core, the number of convex and concave portions also improve water distribution. In a preferred embodiment, a core having between 4 and 6 convex portions yield the desired moisture distribution to the cast tape. 
         [0019]    Further, the thickness of wall  20  may influence the flexibility of core  10 . Referring to  FIG. 4A , the thickness of wall (W T ) may range between about 0.02 inches and about 0.06 inches. Preferably, the wall thickness should be no less than about 0.02 inches (0.05 cm). In an exemplary embodiment, the wall thickness (W T ) is about 0.04 inches (0.1 cm). 
         [0020]    As described above, an aspect of the invention is the flexible resilience of the core  10  that allows the core to move repeatedly between first and second positions. In the embodiment shown in  FIGS. 4A and 4B , the core  10  may flex between a first position  60  shown in  FIG. 4A  to second position  70  shown in  FIG. 4B . For illustrative purposes, the view shown in  FIG. 4B  is an exaggerated view of the second position  70 . The application of a force (F 1 ) to the cast tape  12  and core  10  deepens the longitudinal troughs  45 . For example, in  FIG. 4A , the wall  20  of the core in its first relaxed position  60  has a first amplitude D 1  and accordingly, a first trough  45 A. As shown in  FIG. 4B , application of a radially-inward force (F 1 ) on the cast system  5  flexes the wall  20  into a second position  70  that yields the plurality of convex and concave portions with a second, larger, amplitude, D 2 . This flexing has the effect of forming deeper troughs  45 B. When the force (F 1 ) is removed, the core  10  flexes back to substantially the first position  60  having troughs  45 A. This action will also force the resin into the inner layers of the wound tape. 
         [0021]    When the cast tape  12  and core  10  are flexed while submerged in water, the deepened troughs  45 B will facilitate migration of water between the core  10  and the cast tape  12 . This improves the likelihood that water will distribute throughout the cast tape more effectively prior to resin cure and setting of the cast tape on the patient. 
         [0022]    Although the present invention has been described with exemplary embodiments, it is to be understood that modifications and variations may be utilized without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the appended claims and their equivalents