Spinal implant

• US 4,714,469 A
• Filed: 02/26/1987
• Issued: 12/22/1987
• Est. Priority Date: 02/26/1987
• Status: Expired due to Fees

• Current Assignee: Pfizer Hospital Products Group, Inc. (Pfizer Inc.)
• Original Assignee: Pfizer Hospital Products Group, Inc. (Pfizer Inc.)
• Inventors: Kenna, Robert V.
• Primary Examiner(s): FRINKS, RONALD
• Application Number:
  US07/019,283
• Time in Patent Office: 299 Days
• Field of Search: 623/16-18, 623/20, 128/69, 128/92 YM, 128/92 V, 128/92 VY, 128/92 VD, 128/92 VL, 128/303 R, 128/305
• US Class Current: 606/86.00A
• CPC Class Codes: A61B 17/1757 for the spine
• CPC Class Codes: A61B 2090/033 Abutting means, stops, e.g. abutting on tissue or skin
• CPC Class Codes: A61B 2090/062 penetration depth
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/30771 applied in original prostheses, e.g. holes or grooves
• 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 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2/4657 Measuring instruments used for implanting artificial joints for surgical instruments A61B90/06
• CPC Class Codes: A61F 2002/30769 madreporic
• CPC Class Codes: A61F 2002/30797 internally-threaded
• CPC Class Codes: A61F 2002/30879 Ribs
• CPC Class Codes: A61F 2002/30929 having at least two superposed coatings
• CPC Class Codes: A61F 2002/448 comprising multiple adjacent spinal implants within the same intervertebral space or within the same vertebra, e.g. comprising two adjacent spinal implants
• 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 2310/00029 Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium
• CPC Class Codes: B22F 7/002 of porous nature

Abstract

A spinal implant adapted to replace a disc between adjacent vertebrae having a predetermined thickness and profile chosen to match the space between said vertebrae and characterized by elongated protuberances adapted to be located in grooves drilled in said vertebrae and a porous coating on at least a portion of its surface. A method and apparatus for placement of said spinal implant are also disclosed.

Claims

1. A spinal implant comprising a rigid solid body having a first surface, a second surface and a third surface of predetermined thickness between and perpendicular to said first and second surfaces, each of said first and second surfaces being defined by a substantially D-shaped profile the curved portion of which conforms to the outer profile of the vertebrae between which the implant is adapted to be implanted, said predetermined thickness being chosen to correspond to the space between said vertebrae, each of said first and second surfaces having an elongated protuberance of substantially semi-circular cross-section extending the full width of the surface parallel to the straight side of the D, and at least a portion of each first and second surface having a porous coating thereon.

2. An implant according to claim 1, in which said porous coating is applied to each of said protuberances.

3. An implant according to claim 1, in which a threaded hole and an adjacent locking hole are located in said third surface parallel to the straight side of the D, for holding said implant and placing it in position between vertebrae.

4. An implant according to claim 1, in which the rigid solid body is made from a high strength, biocompatible, corrosion-resistant, cobalt-chromium-molybdenum alloy and the porous coating comprises two layers of substantially spherical particles of the same or similar alloy as the body.

5. A method of placing a spinal implant according to claim 1 between adjacent upper and lower vertebrae in a spinal column, which comprises removing the disc between said vertebrae, measuring the resulting space between said vertebrae, placing in said space a drill guide having dimensions matching said space, drilling semi-cylindrical grooves in the upper and lower vertebrae, which grooves are positioned by use of said guide to match with complimentary protuberances in the implant, removing said drill guide and inserting a spinal implant of predetermined thickness which matches said space by locating the protuberances on the implant in the pre-drilled grooves in the upper and lower vertebrae.

6. A method according to claim 5, wherein the integrity of the space to receive the implant is maintained by appropriate spacers prior to insertion of the implant.

7. A method of replacing a degenerate disc between adjacent upper and lower vertebrae in a spinal column, which comprises inserting two spinal implants in side by side relationship in the space formed by removal of said disc according to the method of claim 5.

8. An apparatus for placement of a spinal implant between adjacent upper and lower vertebrae in a spinal column, which comprises:

(a) a drill guide comprising an elongated arm with a distal end, a proximal end, an upper surface and a lower surface, said proximal end being attached to a handle, semi-cylindrical grooves extending from said distal end to said proximal end in both the upper surface and the lower surface, each of said grooves being adapted to accommodate a drill bit of predetermined diameter;

(b) at least one drill bit of predetermined diameter;

(c) a measuring device associated with or incorporated in said drill guide comprising a linear gauge adapted to measure the depth of the drill bore in the vertebrae the stop means for preventing further drilling when the desired depth is achieved;

(d) two spacers, each comprising an elongated arm having the same diameter as said drill bit of predetermined diameter, said arm being attached at its proximal end to a handle;

(e) a positioning tool comprising an elongated member with a distal end, a proximal end and an axial bore throughout its length, a cylindrical member with a distal end and a proximal end located in said axial bore, the distal end of said cylindrical member being threaded and being adapted to be screwed into a threaded hole located in a spinal implant, the proximal end of said cylindrical member being attached to a knurled knob for turning said cylindrical member to screw or unscrew said threaded distal end and a cylindrical locking key extending from the distal end of said elongated member adjacent and parallel to said threaded axial cylindrical member, which locking key is adapted to slide into a locking hole in a spinal implant.

9. An apparatus according to claim 8 in which the distal end of said elongated member is shaped to match the profile of a spinal implant for which it is to be used.