Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/06—Polyethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/08—Copolymers of ethene
  • C08L23/0807—Copolymers of ethene with unsaturated hydrocarbons only containing four or more carbon atoms
  • C08L23/0815—Copolymers of ethene with unsaturated hydrocarbons only containing four or more carbon atoms with aliphatic 1-olefins containing one carbon-to-carbon double bond
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/04—Homopolymers or copolymers of ethene
  • C08L23/08—Copolymers of ethene
  • C08L23/0807—Copolymers of ethene with unsaturated hydrocarbons only containing four or more carbon atoms
  • C08L23/0823—Copolymers of ethene with unsaturated hydrocarbons only containing four or more carbon atoms with aliphatic cyclic olefins
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/28—Bones
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2/30756—Cartilage endoprostheses
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2002/30001—Additional features of subject-matter classified in A61F2/28, A61F2/30 and subgroups thereof
  • A61F2002/30003—Material related properties of the prosthesis or of a coating on the prosthesis
  • A61F2002/3006—Properties of materials and coating materials
  • A61F2002/30065—Properties of materials and coating materials thermoplastic, i.e. softening or fusing when heated, and hardening and becoming rigid again when cooled
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2210/00—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
  • A61F2210/0071—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof thermoplastic

Definitions

• the invention concerns thermoplastic polymer compositions for skeletal replacements and methods of their production for utilization in human and veterinary medicine.
• the materials so far used for production of skeletal replacements are suitable in clinical practice but, at the same time, show certain drawbacks.
• the drawback all the materials have in common is their mechanical properties, diametrically different from mechanical properties of the bone tissue they replace. All metal materials exhibit Young moduli higher by several orders of magnitude than any bone tissue (for instance, the Young modulus of the femur amounts to ca 18-23 GPa whereas the Young modulus of alloyed steels is around 200 GPa); on the contrary, all hitherto used polymer materials show Young moduli lower by several orders of magnitude.
• Natural transformation of diaphyses can be provided in certain limits by using composite stems with a gradient of elastic properties (gradient of elasticity moduli), having the surface lamella from a material with the same or near Young modulus as corticalis has (Petrtyl M., Pavlansky R.: Hip Implants, US Patent No. 4743263, May 1989; Petrtyl M., Jira A.: Hip Replacements of the Second Generation, In: Engineering Mechanics, Vol. 11, No. 6, 2004, pp. 429-440; Petrtyl M. et al.: How to Ensure the Stability of Hip Replacements, In: Proc: 15th Annual Meeting of the European Orthopaedic Research Society, June 2005, Lisabon, Portugal).
• gradient of elastic properties gradient of elasticity moduli
• a prospective solution to the problem is the composites based on a polymer tolerated by living tissue and reinforced with appropriate high-modulus fibres (e.g. carbon fibres).
• Mechanical properties of a composite material can be controlled by its composition according to the requirements of the envisaged application. From the latest results of materials research follows that copolymers of ethene with bicyclo[2.2.1]hept-2-ene are an appropriate matrix for the composites.
• the polymers show relatively high toughness and it has been experimentally proved that they are well tolerated by living tissue.
• an essential drawback of the copolymers is their low toughness. The drawback can be eliminated by their modification with a polymer component, which would be dispersed in the above matrix.
• the composition of the thermoplastic composition based on the above copolymer and method of its production and processing to polymer parts of skeletal replacements are the subject of the invention described hereinafter.
• the substance of the invention is a thermoplastic composition for skeletal replacements and method of its production.
• the composition consists of 12 - 91 wt.% of a polyolefin with the glass transition temperature higher than 320 K, represented by an ethene bicyclo[2.2.1]hept- 2-ene copolymer with molar concentration of the latter at least 25 % and 75 % at most, of 2 - 72 wt.
• % of a polyolefin with the glass transition temperature lower than 250 K which is (i) ethene homopolymer of density at least 0.92 g.cm "3 and 0.97 g.cm "3 at most or (ii) copolymer of ethene with an ⁇ -olefm selected from a group consisting of propene, but-1-ene, hex-1-ene, oct-1-ene and dec-1-ene, with density at least 0.85 g.cm "3 and 0.96 g.cm "3 at most or a mixture of ethene homopolymer (i) and ethene - ⁇ -olefin copolymer (ii) in any ratio, and of 5 - 50 wt.% of carbon fibres with the carbon content at least 94 wt.%, density at least 1.80 g.cm "3 and 1.92 g.cm "3 at most and a fibre diameter of at least
• the above composition is prepared by mixing in the melt a polyolefin with the glass transition temperature higher than 320 K and a polyolefin with the glass transition temperature lower than 250 K at a melt temperature at least 430 K, irradiating the formed thermoplastic polymer composition with ⁇ -rays or accelerated electrons at a dose of at least 20 IcGy and 250 IcGy at most, to advantage in inert atmosphere, and mixing the irradiated material in the melt with carbon fibres at a temperature of at least 430 K .
• composition according to the invention and of the method of its preparation is the fact that it enables adjustment of mechanical properties of the material in a sufficiently broad range through modification of the contents of individual components so that the implants produced would show the same deformation behaviour as the parts of bones or also cartilages that should be replaced in specific applications.
• the hitherto known materials and methods of production of skeletal replacements do not make possible adjustment of mechanical properties in such broad range.
• blends of the given polymers where the ethene - bicyclo[2.2.1]hept-2-ene copolymer forms a matrix, modified by ionizing radiation show, in comparison with non- irradiated blends of the same composition, pronouncedly higher toughness while keeping the same level of the other mechanical characteristics.
• encapsulation of fibres with polymer-dispersed phase does not proceed in ionizing-radiation-modified blends, which is accompanied by a lowering of the reinforcing effect of fibres.
• Blends of ethene - bicyclo[2.2.1]hept-2-ene copolymer (component A, ethylene unit content
• Table 1 Selected mechanical properties of ethene - bicyclo[2.2.1]hept-2-ene copolymer and ethene - oct-1-ene copolymer blends
• a blend with the A:B component ratio 70:30 was prepared using the procedure given in Example 1, which was subsequently irradiated with ⁇ -rays in a total dose of 25 kGy.
• the thus modified material was processed in the chamber of a laboratory mixer with an admixture of 30 wt.% of carbon fibres (C) at 190 0 C and at the rate 60 min "1 for 8 min.
• An analogous blend was prepared in parallel from the material that was not modified by radiation (Blend 8).
• the values of impact strength, impact tensile strength and Young modulus (at 23 0 C) as properties characterizing toughness and stiffness of the material are compared with the values for corresponding blends containing 5 % of carbon fibres.
• thermoplastic polymer composition according to the invention can be utilized in production of skeletal replacements for human and veterinary medicine.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Compositions Of Macromolecular Compounds (AREA)

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Citations (4)

• 2006
  • 2006-01-31 CZ CZ2006-70A patent/CZ304799B6/cs not_active IP Right Cessation
• 2007
  • 2007-01-31 WO PCT/CZ2007/000007 patent/WO2007087760A1/en active Application Filing

Patent Citations (4)

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