DE4013447C1 - Strong moulding net which contains no toxic material - consisting of carbon fibres coated with thermoplastic material pref. poly:ethyl:methacrylate - Google Patents

Abstract

A moulding net for medicinal purposes consists of carbon fibres coated with a thermoplastic material, pref. polyethyl methacrylate with spaces between the fibres. ADVANTAGE - The net is strong, can be shaped at 50-70 deg.C is stable at normal temps., contains no toxic material and can grow into body tissue.

Description

The invention relates to a modeling network for medical Applications.

Nets that are used in surgery are knows and described for example in DE-OS 29 17 446 ben. They consist of threads of absorbable, organic polymers and / or from non-absorbable threads or wires. The resorbable threads can be trical ciumphosphate, which is the bone growth stimulates. The known networks can be used for Supporting organs, such as the kidney, are used where when they are first adapted to their intended use Be brought into shape. However, this form is - esp especially if the nets are used in one layer - not very stable. In their preferred applications therefore the known networks preferably in connection with Bone cement used. Bone cements are ahead draws from autopolymerizable substances, for example the basis of polymethyl methacrylate. When using the  combination of the mesh and the bone cement, fills the bone cement - except for the volume that the Network occupies - the entire space in which the Kombina tion is introduced. The network consists of re sorbable material, so the mesh will re sorbed and the space released successively with living Bone structure, which into the resulting channels grows, filled. The channels that contain the resorbed material cleared for the renewable body tissue, everyone has dings a very small diameter, which is why the Festig the combination of implant and body tissue should be ring.

The strength of the composite could be improved, by combining a relatively large amount of mesh material with bone cement nier, the associated high porosity would significantly weaken the bone cement. The network exists made of non-absorbable material, for example one Metal, the mesh acts as a reinforcement of the bone cement, which gives it high strength. The well-known networks are when used in conjunction with bone cement become, not reversibly deformable. There is also the fact that in the in situ polymerization of the bone cement hochto xical monomers that have not been reacted to lag behind.

Tex impregnated with a water-hardening plastic resin Tile fabrics are used, for example, as orthopedic Support associations are used, but these can be found under On effect of water only once in a particular Model and then irreversibly harden the shape Form from (DE-OS 37 26 268).  

Thermoplastic deformability is also obtained from known implants made of resorbable plastic (EP-A1-0 17 884; DE 38 30 005 C1; DE-U-89 05 423). Close Lich it is known to implant materials through coals reinforcing fabric fibers (DE-Z: Biomedical engineering, Volume 34 (1989), pages 315 to 319).

It is an object of the invention to provide a modeling network gangs described type so that it as a support scaffolding can be used for replacement plastics for example in the case of facial injuries in which a part of the face must be reconstructed plastically. This Modeling mesh should keep its shape at normal temperature and at higher temperatures can be modeled, no toxic Contains substances and is said to be in local body tissue be able to grow in area.

This task is the beginning of a modeling network described type according to the invention solved in that the Fibers consist of carbon and at least partially are coated with a thermoplastic material that is deformable at temperatures between 50 ° and 70 ° C, and that between the coated carbon fibers Lüc ken remain.

Such a network is at normal ambient temperature dimensionally stable, since the thermoplastic material on the Koh lenstoff fibers these fixed. The tensile strength of the Mo delling network is essentially by the carbon Fibers, but the dimensional stability the thermoplastic coating. An adaptation to one  desired shape can be done in a simple manner are sufficient that the modeling network is heated up Temperatures on the order of 50 ° to 70 ° C. Al The modeling network can only be started by this heating adjust a desired shape, this shape remains after the then cooling.

The specified temperature is particularly advantageous rich because such adjustment may be necessary can also take place in the human body without the heating described burns the adjacent Tissue occur. Quite essential for the fiction moderate modeling network, it is that the coating the Ma leaves the net free, i.e. also after heating and Do not deform into a flat, closed structure , but leaves openings open, into which tissues grow can.

The use of carbon as a fiber material has several advantages:
Carbon is not absorbable and is extremely compatible with body tissues. Carbon is also transparent to X-rays and neither para nor ferromagnetic, so that all modern diagnostic methods, such as computer tomography (CT) and nuclear magnetic resonance measurements (NMR), can be performed postoperatively without harm to the patient and while maintaining the informative value. Added to this is the excellent tensile strength of carbon fibers.

It is convenient to use a thin film for the tensile fiber to be coated from thermoplastic material. The Be  Layering material can, for example, polyethyl meth be acrylate.

To specifically influence the growth of local businesses According to tissue, it is advantageous if the modeling network Contains substances for bioactivation. Bone growth can be, for example, by adding tricalcium stimulate phosphate.

The properties of the modeling network according to the invention in in terms of formability and dimensional stability can be in advantageously vary by turning the network on or off is used in multiple layers and / or by the design of the Network is varied. The network according to the invention can special woven, knitted, knitted or braided.

The following description of preferred embodiment Shapes of the modeling network according to the invention is used in the connection with the drawing of the detailed explanation. The Figure shows a section of an embodiment of the Modeling network according to the invention partly in section.

A modeling network 1 according to the invention consists of tensile fibers which are coated with a thermoplastic material. Carbon is used as the material for the tensile fibers 2 , which is very well compatible with body tissue, transparent to X-rays and neither para- nor ferromagnetic.

The thermoplastic material 3 , with which the tensile Fa is coated or impregnated, becomes thermoplastic at 50 ° to 70 ° C. For example, polyethyl methacrylate is suitable for this.

A network is first used to produce the modeling network made from carbon fibers. The network can - depending on the application - knitted, knitted, woven or ge be braided. Also the size of the free spaces between the fibers depend on the application. Are the free spaces very large, the strength of the finished Network than when they are smaller. But large free spaces hinder the growth of the local Body tissue especially little.

The finished mesh is then made with the thermoplastic mate rial coated or impregnated. For this one is put down molecular form of the thermoplastic material on the Net, which is available in one or two layers, applied and then polymerized; this will be so good there is that the finished product is only highly polymeric Contains ingredients. In another manufacturing ver will drive the already highly polymeric form as powder or applied as a thin film and heated to the Fibers melted. This makes any histotoxicity excluded. Due to the type of coating it can be enough that the thermoplastic material saves so sam is applied to the network that only the fibers be be networked and the gaps that already exist in the network Carbon fibers were present, remain free; this means in other words, that the coating is only too egg leads local fiber bonding.

To stimulate ingrowth of local tissue between the stitches of the modeling network according to the invention can substances on the surface for targeted loading  influence of growth can be applied (bioactivity tion). For example, to stimulate bone growth Tricalcium phosphate suitable.

The following are applications of the invention Modeling network described:

In the operational use of a modeling network, wel ches impregnated with polyethyl methacrylate, it will one- or two-layer mesh in sheet form from a sterile Package removed and roughly cut. Then The net is immersed in hot water or else placed in a microwave oven (also heating with electromagnetic induction (see below) is possible Lich) and then modeled in situ, i.e. on the body. The deformability should be maintained over a long period of time ben, the modeling is done under a radiant heater. The implantation is now complete. The materials of the Network are free from histotoxicity, and the network possesses sufficiently large pores so that a good ingrowth behavior ten can be expected. One is postoperative Progress control possible with imaging methods. The modeling network according to the invention hampers due to its Material properties none of the usual methods of determination den (X-rays, CT and NMR). Is the network permanent undesirable in body tissue, it must be removed because it does not consist of an absorbable material. This is made easier if the network is initially exemplary is made malleable by means of a radiant heater. In In this condition, the net can be removed more gently from the body remove per fabric as without the possibility of ver malleability and exposure to heat.  

One can, for example, for use in the facial ski rurgie shape the modeling net outside the body. There to become by means of computer graphics from passport pictures or other ren recordings of the patient an authentic facial modeled the surface and then the ge saved the model by milling into a suitable mate rial transfer. This is then deformed on this "mask" bare modeling network and then modeled implanted after tumor removal. Leave it with this method, for example with purely cosmetics Sheer indication, also model "dream faces" and realize in body tissue.

Claims (6)

1. modeling network for medical applications from tensile fibers, characterized in that the fibers ( 2 ) consist of carbon and are at least partially coated with a thermoplastic material ( 3 ) which is deformable at temperatures between 50 ° and 70 ° C, and that gaps remain between the coated carbon fibers ( 2 ). 2. modeling network according to claim 1, characterized in that the fibers ( 2 ) are coated with a thin film of thermoplastic material ( 3 ). 3. modeling network according to one of the preceding claims, characterized in that the thermoplastic material ( 3 ) is polyethyl methacrylate. 4. Modeling network according to one of the preceding An sayings, characterized in that there are substances contains for bioactivation.   5. modeling network according to one of the preceding claims, characterized in that the network ( 1 ) is one or more layers. 6. modeling net according to one of the preceding claims, characterized in that the network ( 1 ) is woven, knitted, knitted or braided.