Medical implant or medical implant part comprising porous UHMWPE and process for producing the same

Abstract

The invention provides a medical implant or medical implant part comprising porous ultrahigh molecular weight polyethylene having a weight average molecular weight of about 400,000 atomic mass units or more and a porosity of about 15% to about 65%. The invention further provides a process for producing a medical implant or medical implant part.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS [0001] This patent application claims the benefit of U.S. Provisional Patent Application No. 60 / 504,355, filed Sep. 19, 2003.FIELD OF THE INVENTION [0002] This invention pertains to medical implants and medical implant parts comprising porous ultrahigh molecular weight polyethylene and processes for producing the same. BACKGROUND OF THE INVENTION [0003] The success of orthopaedic implants surgically implanted in living bone substantially depends on achieving and maintaining an enduring bond between the confronting surfaces of the implant and the host bone. Surgical procedures for preparing living bone to receive a surgically implanted orthopaedic device have been known for twenty years or more, but the ideal properties of the surface of the orthopaedic implant which confronts the host bone and processes of preparing the implant surface are the subjects of considerable disagreement. [0004] Ultrahigh molecular weight polyethylene is widel...

AI Technical Summary

Benefits of technology

[0007] The invention provides a medical implant or medical implant part comprising porous ultrahigh molecular weight polyethylene, wherein (i) the ultrahigh molecular weight polyethylene has a weight average molecular weight of about 400,000 atomic mass units or more, (ii) the ultrahigh molecular weight polyethylene has a porosity of about 20% or more, (iii) the average diameter of the pores in the ultrahigh molecular weight polyethylene is about 400 μm or less, and (iv) at least some of the ultrahigh molecular weight polyethylene comprises hydrophilic functional groups attached thereto.

[0008] The invention also provides a medical implant or medical implant part comprising porous ultrahigh molecular weight polyethylene, wherein (i) the ultrahigh molecular weight polyethylene has a weight average molecular weight of about 400,000 atomic mass units or more, (ii) the ultrahigh molecular weight polyethylene has a porosity of about 15% to about 65%, and (iii) at least about 5% (by volume) of the pores in the ultrahigh molecular weight polyethylene have a diameter of about 200 μm or more.

[0009] The invention further provides a process for producing a medical implant or medical i

Problems solved by technology

Surgical procedures for preparing living bone to receive a surgically implanted orthopaedic device have been known for twenty years or more, but the ideal properties of the surface of the orthopaedic implant which confronts the host bone and processes of preparing the implant surface are the subjects of considerable disagreement.

However, virgin ultrahigh molecular weight polyethylene is bio-inert, and living cells (e.g., bone cells, osteoblast-like cells, or soft tissue cells) show relatively little, if any, affinity towards such virgin ultrahigh molecular weight polyethylene.

Accordingly, orthopaedic implants comprising ultrahigh molecular weight polyethylene components that must be anchored to the host bone are at risk for potential failure of the orthopaedic implant unless additional means are undertaken to ensure the establishment and maintenance of a bond between the ultrahigh molecular weight polyethylene component and the host bone.

While each of these means for effectively “bonding” the ultrahigh molecular weight polyethylene component to the host bone have enjoyed varying degrees of success, orthopaedic implants relying on such means are at risk for failure if the particular means (e.g., the ridge, protrusion, or mechanical fastener) fails.

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