Allograft tissue material for filling spinal fusion cages or related surgical spaces

• US 5,910,315 A
• Filed: 07/18/1997
• Issued: 06/08/1999
• Est. Priority Date: 07/18/1997
• Status: Expired due to Term

• Current Assignee: Musculoskeletal Transplant Foundation
• Original Assignee: Arthur A. Gertzman, Sharon Stevenson
• Inventors: Gertzman, Arthur A., Stevenson, Sharon
• Primary Examiner(s): Page, Thurman K.
• Assistant Examiner(s): Seidleck, Brian K.
• Application Number:
  US08/943,549
• Time in Patent Office: 690 Days
• Field of Search: 424/422, 424/423, 424/424, 424/425, 424/426, 523/115, 523/116, 623/16, 623/17
• US Class Current: 424/422
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• 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 2/4601 for introducing bone substitute, for implanting bone graft implants or for compacting them in the bone cavity
• CPC Class Codes: A61F 2002/2835 Bone graft implants for filling a bony defect or an endoprosthesis cavity, e.g. by synthetic material or biological material
• CPC Class Codes: A61F 2002/30593 hollow
• CPC Class Codes: A61F 2310/00023 Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61L 27/3608 Bone, e.g. demineralised bone matrix [DBM], bone powder
• CPC Class Codes: A61L 27/3654 Cartilage, e.g. meniscus
• CPC Class Codes: A61L 27/3658 Intervertebral discs mechanical aspects and structures of intervertebral discs A61F2/442

Abstract

An extrudable allograft bone tissue material for filling surgical sites can be made from mineralized or demineralized cortical, cancellous, or cortical/cancellous bone powder. A method is disclosed for reconstituting the bone powder in a syringe which includes the steps of placing lyophilized bone material of predetermined mixed size in a syringe barrel having a distal circular opening that ranges in diameter from about 8 mm to about 15 mm and adding a volume of sterile fluid to wet the bone powders. The excess sterile fluid is drained through the bone allowing the fluid to remain in constant engagement with the bone for a period of time until the mass is fully reconstituted from its initial lyophilized state and attains self-adherence so that the mass conforms to the shape of the barrel of the syringe and retains the barrel shape and integrity after extrusion from the syringe into the surgical site in a semisolid mass.

Claims

1. A method for filling a surgical site with bone material, comprising the steps of:

placing a mass of lyophilized bone chips of predetermined mixed size ranging from 100 microns to 2.0 mm, said mass of chips including a packing of the interstitial spaces between the larger granular tissue particles of particulate cortical bone powder ranging from about 100 to about 300 microns and larger sized granular tissue particles in a straight-walled barrel of a syringe having a circular opening at the distal end thereof, ranging from about 8 mm to about 15 mm in diameter;

tamping the mass of bone chips to fill air pockets in the syringe;

adding a volume of sterile fluid ranging from about 3 to about 6 times the bulk of the volume of the mass of bone chips to provide adequate wetting;

allowing the fluid to flow through said mass of bone chip to filly hydrate the bone chips for a period of time hydrating the bone chips until the mass is fully reconstituted from its initial lyophilized state and obtains chip self-adherence conforming to the shape of the lumen of the barrel of the syringe and retain such shape and geometric integrity;

draining sterile fluid from the syringe; and

depressing a plunger of the syringe and extruding the shaped bone material in a semi-solid mass which retains its shape and integrity in a surgical site.

2. A method of filling a surgical site with bone material as claimed in claim 1 wherein said sterile fluid comprises sterile water with about 10% glycerol by volume and said period of time for hydration ranges from about twenty minutes to about thirty minutes.

3. A method of filling a surgical site as claimed in claim 1 wherein said surgical site is a spinal fusion cage.

5. A method of filling a surgical site with a shape-retaining, semi-solid bone composition as claimed in claim 1 wherein said bone particles are comprised of cancellous bone powder having a particle size ranging from about 250 to about 420 microns.

6. A method of filling a surgical site with a shape-retaining, semi-solid bone composition as claimed in claim 1 wherein said demineralized cortical bone particles packing the interstitial spaces have a particle size ranging from about 420 to about 850 microns.

4. A method of filling a surgical site with a shape-retaining, semi-solid bone composition, comprising the steps of:

placing a plurality of lyophilized bone particles of mixed sizes ranging from a particulate powder mixed with larger granular tissue particles, said lyophilized bone particles comprising a mixture containing about 75% by volume of lyophilized, demineralized cortical/cancellous bone powder ranging from 0.5 to 2 mm particle size and about 25% by volume of lyophilized, demineralized cortical bone powder ranging from 100 to 300 micron particle size to provide a bone composition with a packing of the interstitial spaces between the larger granular tissue particle with particulate powder or other granular tissue particles in a straight-walled extrusion vessel having an opening at the distal end thereof which opening has substantially the same dimensions as the interior of a spinal fusion chamber;

pouring a volume of hydrating solution into an open proximal end of said extrusion vessel and allowing the solution to flow through said mass of bone particles to fully hydrate same;

removing the air bubbles from the hydrating solution which adhere to said plurality of bone particles;

allowing the bone particles to hydrate for at least 20 minutes in said solution so that said bone particles become an extrudable, shape-retaining semi-solid mass; and

extruding said bone particle composition from said extrusion vessel into said surgical site in a semi-solid shape which substantially retains the shape of the interior of said extrusion vessel.

7. A method of filling a surgical site with a shape-retaining, semi-solid bone composition as claimed in claim 4 wherein said hydrating solution is saline.

8. A method of filling a surgical site with a shape-retaining, semi-solid bone composition as claimed in claim 4 wherein said hydrating solution is at least 90% water by volume and not more than 10% glycerol by volume.

9. A method of filling a surgical site with a shape retaining semi-solid bone composition as claimed in claim 4 wherein said hydrating solution volume is about three times the bulk volume of the bone composition.

10. An extrudable, shape-retaining bone filler composition, comprising:

a mass of freeze dried demineralized bone particles having a particle size ranging from about 100 to about 1,000 microns; and

packed together with the smaller particles packing the interstitial spaces between the larger granular tissue particles in a walled container so that the interstices formed between the largest bone particles are substantially filled; and

,

a sterile hydrating agent having a volume ranging from one to three to one to six in relation to the volume of the bone particle mass, and an elution speed through the bone particle mass ranging from two to six minutes, said bone particle mass being placed in contact with said hydrating agent for at least twenty minutes to provide a swell volume of the bone particles of at least about 40%.

11. An extrudable, shape-retaining bone filler composition as claimed in claim 10 wherein said hydrating agent is water.

12. An extrudable, shape-retaining bone filler composition as claimed in claim 10 wherein said hydrating agent is a saline solution.

13. An extudable, shape-retaining bone filler composition as claimed in claim 10 wherein said hydrating agent is at least 90% water by volume and not more than 10% glycerol by volume.

17. An extrudable, shape-retaining bone filler composition as claimed in claim 10 wherein said bone particles are cortical bone particles ranging in particle size from about 500 to about 1,000 microns.

18. An extrudable, shape-retaining bone filler composition as claimed in claim 10 wherein said bone particles are cortical bone particles ranging in particle size from about 420 to about 850 microns.

14. An extrudable, shape-retaining bone filler composition, comprising:

a mass of freeze dried demineralized cancellous bone particles having a particle size ranging from about 250 to 420 microns;

packed together in a walled container so that the interstices between the largest bone particles are substantially filled; and

,

a sterile hydrating agent having a volume ranging from one to three to one to six in relation to the volume of the bone particle mass, and an elution speed over five minutes and when immersing the bone particle mass, for at least twenty minutes provides a swell volume of the bone particles ranging from about 50% to 150%.

15. An extrudable shape retaining bone filler composition as claimed in claim 14 wherein said hydrating agent is water.

16. An extrudable, shape-retaining bone filler composition as claimed in claim 14 wherein said hydrating agent is at least 90% water by volume and not more than 10% glycerol by volume.