Howmedica Osteonics Corporation

Pfizer Hospital Products Group, Inc.

Benoist Girard Sas

John H Dumbleton

Aiguo Wang

Shi-Shen Yau

Aaron Essner

Kathy K Wang

Larry J Gustavson

Casper F Stark

Eric Jones

Paul A Higham

Qi-Bin Bao

Ruey Y Lin

Thomas E Crippen

Ruey Lin

A method of producing an improved polyethylene, especially an ultra-high molecular weight polyethylene utilizes a sequential irradiation and annealing process to form a highly cross-linked polyethylene material. The use of sequential irradiation followed by sequential annealing after each irradiation allows each dose of irradiation in the series of doses to be relatively low while achieving a total dose which is sufficiently high to cross-link the material. The process may either be applied to a preformed material such as a rod or bar or sheet made from polyethylene resin or may be applied to a finished polyethylene part.

Sequentially cross-linked polyethylene

A method of producing an improved polyethylene, especially an ultra-high molecular weight polyethylene utilizes a sequential irradiation and annealing process to form a highly cross-linked polyethylene material. The use of sequential irradiation followed by sequential annealing after each irradiation allows each dose of irradiation in the series of doses to be relatively low while achieving a total dose which is sufficiently high to cross-link the material. The process may either be applied to a preformed material such as a rod or bar or sheet made from polyethylene resin or may be applied to a finished polyethylene part. If applied to a finished polyethylene part, the irradiation and annealing must be accomplished with the polyethylene material not in contact with oxygen at a concentration greater than 1% oxygen volume by volume. When applied to a preform, such as a rod, the annealing of the bulk polymer part of the rod from which the finished part is made must take place on the rod before the implant is machined therefrom and exposed to oxygen.

According to the present invention a prosthetic bearing component is formed from a composite synthetic plastics material comprising an injection molded thermoplastic polymeric matrix reinforced by a pitch based carbon fiber and having a bearing surface which has been machined with a surface roughness with a value less than R 2 &mgr;m. Such components have shown superior wear qualities. Preferably the bearing surface shape is machined with tolerances of 0.1 to 0.15 mm. The composite material must be capable of withstanding a radiation value of at least 2.8 Mega Rads (MRad). In components in which the bearing surface is substantially or part spherical a sphericity of 0.3 &mgr;m within a solid angle of 45&deg; is required.

Prosthesis bearing component

An implantable material for promoting bone growth has a microporous structure exhibiting an average pore size of at least 30 .ANG.. The porous biomaterial is capable of retaining macromolecules having a molecular weight of at least 15,000 and up to 500,000.

Bone growth stimulator

A beam adapted for implantation within a bone is able to support bending and torsional loading forces applied thereto. The beam has a stiffness defined by a modulus elasticity, which stiffness varies along the length of the beam to match the corresponding stiffness of the cortical bone adjacent the beam after implantation within the bone. The beam is made from an elongated core formed of continuous filament carbon fibers embedded in a thermoplastic polymer matrix with the carbon filaments extending in a direction substantially parallel to the longitudinal axis of the beam. Encasing the core is a filler molded to the core, which filler is made up of the same thermoplastic polymer as the core but contains no reinforcing carbon fibers. The filler provides the prosthesis with a shape generally conforming to the desired shape of the final prosthetic implant. A sheath formed of carbon reinforced filament fibers embedded in the thermoplastic polymer is wound in spiral formation around the filler and molded thereto. The winding angle and the sheath thickness along the beam may be varied to vary the modulus of elasticity to match that of the cortical bone adjacent thereto.

Composite orthopedic implant

Method for preparing a high strength, low modulus, ductile, biocompatible titanium base alloy containing one or more isomorphous beta stabilizers, eutectoid beta stabilizers and optional alpha stabilizers, characterized by a modulus of elasticity not exceeding 100 GPa; comprising blending pre-selected amounts of the alloying ingredients, melting the blend in a plasma arc furnace, allowing the melt to cool and solidify, vaccum arc remelting and thermomechanically processing the resulting solid to provide the desired alloy.

Method of making high strength, low modulus, ductile, biocompatible

A high strength, low modulus, ductile, biocompatible titanium base alloy containing one or more isomorphous beta stabilizers, eutectoid beta stabilizers and optional alpha stabilizers, characterized by a modulus of elasticity not exceeding 100 GPa; a method for the preparation of said alloy and prostheses made from said alloy.

High strength, low modulus, ductile, biopcompatible titanium alloy

A dispersion strengthened cobalt-chromium-molybdenum alloy produced by gas atomization containing a fine oxide dispersion, and characterized, after fabrication by gas atomization, thermomechanical processing and further high temperature exposure, by excellent corrosion resistance, high fatigue strength, high ductility and high temperature stability; a process for producing said alloy and prostheses formed from said alloy.

Growing community of inventors

Ridgewood, NJ, United States of America

John H Dumbleton