Artificial disc

• US 5,893,889 A
• Filed: 06/20/1997
• Issued: 04/13/1999
• Est. Priority Date: 06/20/1997
• Status: Expired due to Fees

• Current Assignee: Michael Harrington
• Original Assignee: Michael Harrington
• Inventors: Harrington, Michael
• Primary Examiner(s): Yu, Mickey
• Assistant Examiner(s): SNOW, BRUCE EDWARD
• Application Number:
  US08/879,410
• Time in Patent Office: 662 Days
• Field of Search: 623/17, 623/18, 606/61
• US Class Current: 623/17.16
• CPC Class Codes: A61B 17/86 Pins or screws or threaded wires; nuts therefor A61B17/72 take precedence
• CPC Class Codes: A61F 2/30742 Bellows or hose-like seals; Sealing membranes A61B17/8808 takes precedence; sealing membranes for retaining bone substitute A61F2/2846
• CPC Class Codes: A61F 2/4425 made of articulated components
• CPC Class Codes: A61F 2002/302 toroidal, e.g. rings
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30495 using a locking ring
• CPC Class Codes: A61F 2002/30563 having elastic means or damping means, different from springs, e.g. including an elastomeric core or shock absorbers
• CPC Class Codes: A61F 2002/30785 parallel
• CPC Class Codes: A61F 2002/30841 Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/30891 Plurality of protrusions
• CPC Class Codes: A61F 2002/443 having two transversal endplates and at least one intermediate component
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2230/0065 toroidal, e.g. ring-shaped, doughnut-shaped
• CPC Class Codes: Y10S 606/907 Composed of particular material or coated

Abstract

A disc prosthesis for insertion between vertebrae of the spin has upper and lower members and a pivot ball retained in a socket to prevent the ball from becoming removed from the socket. Also, a shock absorbing member is fitted between the upper and lower member of the prosthesis. The upper and lower members are also vertically movable to compress the shock absorbing member and absorb shock in the spine.

Claims

1. An intervertebral disc protheses for replacement of a disc between an upper vertebrae and a lower vertebrae comprising,

a lower member having a lower mounting surface for attachment against an upper surface of said lower vertebrae, said lower member having an upper surface,

an upper member having an upper mounting surface for attachment against a lower surface of said upper vertebrae, said upper member having a lower surface,

a pivot ball extending from a post from one of said upper member and said lower member,

the other of said upper member and said lower member having an elongate cavity therein,

means on said other of said upper member and said lower member for retaining said pivot ball in said cavity,

an elastomeric shock absorbing member between said upper member and said lower member, said elastomeric shock absorbing member compressible between a relief condition wherein said upper surface of said lower member has a first spacing from said lower surface of said upper member, and a compressed condition wherein said upper surface of said lower member has a second spacing from said lower surface of said upper member, said second spacing being less than said first spacing, and

said pivot ball is vertically movable within said elongate cavity to permit compression of said shock absorbing member from said relief condition to said compressed condition.

2. An intervertebral disc in accordance with claim 1 and further comprising,

one of said upper member and said lower member having an annular groove around the circumference thereof,

a retaining ring sized for insertion in said groove, and

a tubular membrane attached to said retainer ring.

3. An intervertebral disc in accordance with claim 1 wherein,

said means for retaining said pivot ball in said cavity including an annular retainer having a central opening with a diameter less than a diameter of said pivot ball.

4. An intervertebral disc prostheses for replacement of a disc between an upper vertebrae and a lower vertebrae comprising,

a lower member having a lower mounting surface for attachment against an upper surface of said lower vertebrae,

an upper member having an upper mounting surface for attachment against a lower surface of said upper vertebrae,

one of said upper member and said lower member have a base portion with a tubular central portion having an inner diameter,

an annular collar around said tubular central portion, said annular collar having a central opening,

a pivot ball extending from a post from the other of said upper member and said lower member,

said pivot ball having a diameter less than said inner diameter,

said central opening of said collar having a diameter which is less than said diameter of said pivot ball whereby said collar retains said pivot ball in said tubular central portion,

an elastomeric shock absorbing member between said upper member and said lower member, said elastomeric shock absorbing member movable between a relief condition wherein said upper member has a first spacing from said lower member and a compressed condition wherein said upper member has a second spacing from said lower member, and

said pivot ball vertically movable within said tubular central portion of said one of said upper member and said lower member to permit compression of said shock absorbing member from said relief condition to said compressed condition.

5. An intervertebral disc in accordance with claim 4 and further comprising,

one of said upper member and said lower member having an annular groove around the circumference thereof,

a retaining ring sized for insertion in said groove, and

a tubular membrane attached to said retainer ring.

6. An intervertebral disc in accordance with claim 4 and further comprising an elastomeric plug within said tubular central portion.