Surgery: splint – brace – or bandage – Orthopedic bandage – Splint or brace
Reexamination Certificate
2000-02-16
2002-03-19
Brown, Michael A. (Department: 3764)
Surgery: splint, brace, or bandage
Orthopedic bandage
Splint or brace
C602S005000, C602S006000
Reexamination Certificate
active
06358220
ABSTRACT:
The invention relates to a thermoplastic casting material, especially a thermoplastic casting material in roll form, preferably for orthopedic and other medical applications for immobilization of extremities and/or joints. Additionally, the invention relates to a method for the production of this thermoplastic casting material.
Alternative casting materials based on synthetic polymers have been known for some time in addition to the customary plaster of paris cast materials used for a long time. These possess the advantages compared to plaster of paris casts that they have improved mechanical properties, that they are unaffected by water and, as a consequence, are washable, and ensure an increased wearing comfort and better mobility as a result of their rapid applicability and hardening and due to their light weight. Furthermore, in contrast to plaster materials, casting systems based on synthetic polymers are translucent to x-ray radiation and thus allow x-ray follow-up examinations without having to remove the casting.
Plaster of paris as well as the casting materials based on plastic are essentially composed of an organic or inorganic textile supporting material and the plaster and/or synthetic polymer material applied thereto. With plastic materials, a differentiation is to be made between irreversibly hardenable materials and thermoplastic, reversibly moldable materials.
Among the irreversibly hardenable synthetic polymer casting materials, water-hardening systems have primarily prevailed that contain reactive polyurethane prepolymers as hardenable synthetic polymer components which harden through contact with water. By suitably choosing the formulation, casting materials can be attained that, after dipping in water, harden within a time period that allows the professional application and modeling of the casting material to the human or animal body. As long as the synthetic polymer is not hardened, the individual layers of the casting material are capable of sticking to each other whereby a cast comprising several layers of the casting material is finally obtained.
With thermoplastic, reversibly moldable casting materials, the self-adhesive characteristic is achieved by heating the thermoplastic polymer to or above the respective softening temperature. The material hardens again upon cooling, whereby it remains pliable and capable of being modeled for some time at temperature below the melting point. A multi-layered self-bound casting system is obtained after the hardening of the thermoplastic resin.
Although they dominate the market at the present time, the hardenable synthetic polymer casting materials, i.e. water-hardenable casting materials based on polyurethane resins, are disadvantageous in comparison to thermoplastic systems. A moisture-free production and a complicated packaging of the product that is impermeable to water and air is necessary as a result of the desired property of water-hardenability. Additionally, the water-hardenable resin formulations are complex and correspondingly expensive. By maintaining conditions which are as moisture-free as possible, the storage stability of approximately 24 months is also low. Additionally, the isocyanates contained in the polyurethane resins are sensitizing, irritating and damaging to health and, as a result, are not without risk in use with high-risk patients.
A problem inherent to the hardenable as well as the thermoplastic casting materials is that an adhesion of the layers at the position of application is desired and necessary, but on the other hand, an adhesion of the layers at a point in time other then during the direct application must be avoided.
Thus, WO 95/19751 describes an orthopedic casting material of a support fabric and a material applied thereto of a hardenable resin and a filler bound thereto. In order to prevent the individual layers of the casting material from sticking together during storage, a volatile, water-soluble liner is applied to the material as a separator. This liner is dissolved and removed when the casting material equipped with the water-hardenable resin is brought into contact with water to initialize hardening.
A thermoplastic casting material is described in U.S. Pat. No. 4,445,873. It consists of a flexible fabric substrate, typically of a knitted cotton material, and is coated with a polyester resin. This coated material remains flexible and can be stored in the form of rolls. In order that the individual layers of the material do not adhere to each other when softening the resin in hot water before they are applied to the desired location on the body, a polyethylene oxide layer is applied to the resin/support composite. This layer dissolves upon softening in water and thus releases the self-adhering surface of the thermoplastic resin.
In U.S. Pat. No. 3,420,231 a casting material consisting of a substrate and a thermoplastic resin is described as known which is present in rolled-up form and has a separation material to prevent the adhesion of neighboring layers, for example a paper interlining. This arrangement is regarded as unsatisfactory and U.S. Pat. No. 3,420,231 proposes to replace the interliner to be removed before application with a coating of a water-soluble resin with inverse solubility in water. As a result of the inverse solubility, the interlayers are not dissolved when heating and softening of the thermoplastic resin in hot water. After application of the casting material, the protective layer dissolves in the adhering, now cooled residual water and allows adhesion of the individual layers.
Finally, U.S. Pat. No. 4,143,655 discloses an orthopedic casting material that is constructed of a textile substrate and a thermoplastic polymer applied thereto. A polyethylene film mesh is applied to one side of the coated substrate as a separation layer for preventing the adhesion of neighboring layers. As a result, adhesion of the layers is prevented when heating the casting material. Upon application of the casting material, the polyethylene film is pulled off and an adhesion of the individual layers with each other is thus made possible.
The measures described above for preventing the undesired adhesion of hardenable or thermoplastic polymer casting materials brings about a certain improvement in comparison to completely unprotected casting material systems, but are however still unsatisfactory and not suitable to prevent an undesired adhesion of the casting material with certainty.
Thus, when using a water-soluble separator, the protective effect is already lost in the water bath into which the casting material is brought to the required temperature for softening the thermoplastic polymer or for initializing the hardening of the water-hardenable synthetic polymer. Hence, the possibility exists that an adhesion of the neighboring layers of the casting material which are present for the most part in rolled up form, occurs after removal from the water bath or already in the water bath.
Furthermore, the use of a water-soluble or inverse water-soluble protective film is connected with the limitation that a water bath must be used for heating the material. Heating, for example, via hot air blower or in an oven is not possible.
The use of interlinings that are to be removed before application is unsatisfactory because handling is clearly made more difficult by the separation of the material at the moment of use and, furthermore, unnecessary waste is created. Consequently, the object of the invention was to develop a thermoplastic casting material that allows good adhesion of the neighboring casting material layers upon application but effectively prevents adhesion of the layers up to this time point without the use of a separator such that the material can be easily unrolled and is easy to handle and does not lead to the creation of waste or to the contamination of the water bath used.
Furthermore, a method is to be made available that allows the production of such a casting material in a simple and inexpensive manner.
The above problems could be solved according to the inve
Burger Joachim
Langen Gunter
Meister Marita
Berkowitz Marvin C.
Brown Michael A.
Hamilton Lalita M.
Karl Otto Braun KG
Nath Gary M.
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