Composite orthopedic implant

US5181930A · kind A · utility

Assignee

• Pfizer Hospital Products Group, Inc. · US

Inventors

• John H. Dumbleton · Ridgewood, US
• Ruey Y. Lin · Williamsville, US
• Casper F. Stark · Pompton Lakes, US
• Thomas E. Crippen · Tyler, US

Key dates

• Filing date: Apr 10, 1991
• Grant date: Jan 26, 1993
• Expiry date: Apr 10, 2011

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B29L2031/7532
• WIPO field: Medical technology
• WIPO sector: Instruments

Abstract

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.