US 5,879,407 A · Wear resistant ball and socket joint

Abstract

A ball and socket joint providing longevity especially suitable for use in implants in human bodies. The ball is designed to incorporate specified strength, hardness, and smoothness characteristics. The socket has a cooperating bearing surface which is less hard than that of the ball. This combination of characteristics lead to maximal mutual bearing contact which minimizes local friction and abrasion. Both components are biologically inert. One component is hydrophilic. The ball is preferably formed from a ceramic, such as a metal or silicon oxide or carbide. The socket preferably has a noble metal alloy liner partially surrounding the ball. The socket further includes an insulator isolating the liner from the socket structural member, should the latter be formed from a different metal. The liner can be formed in complementary segments to avoid fracture or splitting. The liner is either mechanically entrapped by the socket structural member or is adhered thereto. The novel ball and socket joint minimizes wear and chemical, electrochemical, and mechanical deterioration in the environment of the human body.

Claims10

Dependent claims

A wear resistant ball and socket joint, comprising:

a socket having a contact surface;
and
a ball disposed in spherical bearing contact relationship to said contact surface of said socket,
one of said ball and said contact surface of said socket having a smoothness finish of magnitude of less than 0.3 microinch, and a hardness characteristic greater than that of the other one of said ball and said contact surface of said socket;
and where one of said ball and said contact surface further has:
a first Mhos hardness characteristic of at least 11;
a tensile strength of at least 30,000 psi;
a compressive strength of at least 200,000 psi;
a Weibull modulus greater than nine, and further having a hydrophilic characteristic;
and where
the other of said ball and said contact surface has:
a second Mhos hardness characteristic less than that of said first Mhos hardness characteristic;
whereby
said ball and socket joint is suitable for a prosthetic implant for a person and will provide a suitable service life over an average life expectancy.

11 more elements

Dependencies are inferred from the claim text.

Wear resistant ball and socket joint

Life of this patent

Wear resistant ball and socket joint

Life of this patent

Abstract

Claims10