Spinal implant

• US 4,863,476 A
• Filed: 08/28/1987
• Issued: 09/05/1989
• Est. Priority Date: 08/29/1986
• Status: Expired due to Term

• Current Assignee: Zimmer Technology Incorporated (Zimmer Biomet Holdings, Inc.)
• Original Assignee: John A.N. Shepperd
• Inventors: Shepperd, John A. N.
• Primary Examiner(s): Apley, Richard J.
• Assistant Examiner(s): Isabella, David J.
• Application Number:
  US07/090,610
• Time in Patent Office: 739 Days
• Field of Search: 623/16-23, 128/92 YY, 128/92 YM, 128/85
• US Class Current: 623/17.15
• CPC Class Codes: A61F 2/30724 Spacers for centering an implant in a bone cavity, e.g. in a cement-receiving cavity
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/442 Intervertebral or spinal discs, e.g. resilient non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455
• CPC Class Codes: A61F 2/4455 for the fusion of spinal bodies, e.g. intervertebral fusion of adjacent spinal bodies, e.g. fusion cages intervertebral discs A61F2/442
• CPC Class Codes: A61F 2/446 having a circular or elliptical cross-section substantially parallel to the axis of the spine, e.g. cylinders or frustocones
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/30113 circular
• CPC Class Codes: A61F 2002/30224 cylindrical
• CPC Class Codes: A61F 2002/3037 Translation along the common longitudinal axis, e.g. piston
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30556 for adjusting thickness
• CPC Class Codes: A61F 2002/30579 with mechanically expandable devices, e.g. fixation devices
• CPC Class Codes: A61F 2002/30594 slotted, e.g. radial or meridian slot ending in a polar aperture, non-polar slots, horizontal or arcuate slots
• CPC Class Codes: A61F 2002/30975 made of two halves
• CPC Class Codes: A61F 2002/4627 with linear motion along or rotating motion about the instrument axis or the implantation direction, e.g. telescopic, along a guiding rod, screwing inside the instrument
• CPC Class Codes: A61F 2002/4628 with linear motion along or rotating motion about an axis transverse to the instrument axis or to the implantation direction, e.g. clamping
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0033 made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2230/0006 circular
• CPC Class Codes: A61F 2230/0069 cylindrical
• CPC Class Codes: A61F 2250/0009 : for adjusting thickness
• CPC Class Codes: A61F 2310/00017 : Iron- or Fe-based alloys, e.g. stainless steel
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00029 : Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium
• CPC Class Codes: A61F 2310/00179 : Ceramics or ceramic-like structures
• CPC Class Codes: A61F 2310/00796 : Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite

Abstract

A apinal implant has an elongate body which is divided into two portions with mutually opposed contact surfaces and is for insertion into the joint space between two adjacent vertebrae. A cam device or cam devices are movable between the contact surfaces to expand or increase the spacing between the body portions so as to increase the spacing between the adjacent vertebrae.

The implant has a porous external surface to facilitate bore and cartilage tissue growth therein. Alternatively, the external surface is smooth and coated with a bioactive material such as a hydroxyapatite, for example, tricalcium phospahte. In both instances bone, cartilage tissue and external surfaces of the implant are fused together to prevent migration of the implant. Advantageously, insertion of the implant requires a minimum incision in skin and cartilage tissue.

Claims

1. A spinal implant for insertion in the joint space between adjacent vertebrae comprising:

an elongated member divided longitudinally into two body portions which are movable between an open position, in which an external surface of each body portion is adapted to engage an adjacent vertebrae, and as closed position in which opposign adjacent flat contact surfaces on each said body portion abut each other, said body portions having a recess in eah of said flat contact surfaces so that said recesses define, in said closed position, an elongated aperture located centrally along the spinal implant; and

an expansion means adapted to be disposed within said aperture so as to move said body portions between said open and closed positions and adjust the joint spacing between adjacent vertebrae, said expansion means having cam means that engage oppositely pitched thread patterns on end portions of a rod assembly so that the rotation of said rod assembly causes the cam means to move in unison along said rod assembly and between said contact surfaces so as cause said body surfaces to be moved.

2. A spinal implant as claimed in claims 1 wherein the exterior surface of the implant is of a porous material.

3. A spinal implant as claimed in claims 1 wherein the exterior surface of the implant is smooth and coated with a bioactive material to chemically bond the bone and cartilage tissue of the vertebrae to the implant.