Polyporous hollow bone screw

• US 8,579,947 B2
• Filed: 09/14/2010
• Issued: 11/12/2013
• Est. Priority Date: 09/14/2009
• Status: Active Grant

• Current Assignee: Yangguan Wu
• Original Assignee: Yangguan Wu
• Inventors: Wu, Yangguan
• Primary Examiner(s): KEMMERER, ELIZABETH
• Application Number:
  US12/807,785
• Publication Number:
  US 20110093020A1
• Time in Patent Office: 1,155 Days
• Field of Search: None
• US Class Current: 606/301
• CPC Class Codes: A61B 17/74 Devices for the head or neck or trochanter of the femur trochanteric devices connected to the proximal part of an endoprosthetic femoral shaft A61F2/30739; endoprosthetic internal fixation devices for the head or neck of the femur A61F2/3601
• CPC Class Codes: A61B 17/866 Material or manufacture
• CPC Class Codes: A61B 17/8685 comprising multiple separate parts
• CPC Class Codes: A61B 2017/561 Implants with special means for releasing a drug
• CPC Class Codes: A61K 2300/00 Mixtures or combinations of active ingredients, wherein at least one active ingredient is fully defined in groups A61K31/00 - A61K41/00
• CPC Class Codes: A61K 35/28 Bone marrow; Haematopoietic stem cells; Mesenchymal stem cells of any origin, e.g. adipose-derived stem cells
• CPC Class Codes: A61K 38/1875 Bone morphogenic factor; Osteogenins; Osteogenic factor; Bone-inducing factor
• CPC Class Codes: A61K 9/0024 Solid, semi-solid or solidifying implants, which are implanted or injected in body tissue compositions for intravenous administration, normal injectable solutions or dispersions for, e.g. subcutaneous administration A61K9/0019; brain implants A61K9/0085; (coated) prostheses, catheters or stents A61L
• CPC Class Codes: A61K 9/19 lyophilised , i.e. freeze-dried, solutions or dispersions lyophilised products with subsequent particle size reduction A61K9/14; granules or pellets made by lyphilisation A61K9/1682; solid oral dosage forms made by lyophilisation A61K9/2095; lyophilisation additives A61K47/00
• CPC Class Codes: A61K 9/5161 Polysaccharides, e.g. alginate, chitosan, cellulose derivatives; Cyclodextrin
• CPC Class Codes: A61L 2300/252 Polypeptides, proteins, e.g. glycoproteins, lipoproteins, cytokines
• CPC Class Codes: A61L 2300/412 Tissue-regenerating or healing or proliferative agents
• CPC Class Codes: A61L 2300/64 Animal cells
• CPC Class Codes: A61L 2400/12 Nanosized materials, e.g. nanofibres, nanoparticles, nanowires, nanotubes; Nanostructured surfaces
• CPC Class Codes: A61L 31/129 containing macromolecular fillers
• CPC Class Codes: A61L 31/146 Porous materials, e.g. foams or sponges
• CPC Class Codes: A61L 31/16 Biologically active materials, e.g. therapeutic substances A61L31/047 takes precedence
• CPC Class Codes: A61P 19/08 for bone diseases, e.g. rachitism, Paget's disease
• CPC Class Codes: C08L 5/08 Chitin; Chondroitin sulfate; Hyaluronic acid; Derivatives thereof
• CPC Class Codes: C08L 89/06 derived from leather or skin , e.g. gelatin

Abstract

Present invention depicts a poly-porous (micropore) hollow screws as diffusion chamber filled with core matrix for targeted delivery of growth factors and bone marrow stem cells. The screws comprise at least two parts: the distal part of the screw consists of the tip of the screw made of poly porous material and hollow inside proximally. It has threaded navel attached to the threaded nipple of the distal part of the proximal screw which has the screw head and is made of the solid material of the same kind. The screw head had hexagonal recess targeted for screw driver insertion. Assembly of screw created a chamber in the middle of the screw. The chamber is filled with core matrix consisting of gelatin nano-particles pre-impregnated with BMPs (BMP2/BMP7 for bone or BMP12 for tendon, ligament) and fibrin sealants or Chitosan dispersed with bone marrow stem cells and/or other growth factors. Bioactive protein core material is prepared during the surgery and filled the chamber of the screw by the surgeon. Fibrin sealants or Chitosan will polymerize to form a gel to hold the growth factors and stem cell in place. The screw can be used as the lag screw or other function to provide mechanical fixation in variety of condition. Once the screw implanted in the human body, the fibrin sealant or Chitosin/gelatin nano-particles are gradually degraded and slowly release growth factors and stem cells via micropores of screw to facilitate the bone healing and regeneration. The gelatin nanoparticles and fibril sealant/or Chitosan matrix also serve as the scaffold and platform for bone in-growth to the screw or alternatively, the stem cell inside of screw can regenerate new bone, providing the biological fixation. At the mean time as the bone regenerate and/or in growth, mechanical strength of the screw increased.

Claims

1. A polyporous hollow bone screw which serves as a diffusion chamber, comprising:

a hollow bone screw forming a hollow chamber, said hollow bone screw being filled with a biodegradable core matrix as a carrier for bioactive materials;

the biodegradable core matrix being selected from the group consisting of gelatin nanoparticles, fibril sealant, and chitosan nanoparticles; and

the bioactive materials being selected from the group consisting of growth factors and bone marrow stem cells.

2. The polyporous hollow bone screw according to claim 1, wherein said bone screw includes a distal part A and a proximal part B, wherein said distal part A is made of a porous material having interconnected pores ranging from 200-500 microns in diameter and a porosity of 40-50% and said proximal part B is titanium or tantalum.

3. The polyporous hollow bone screw according to claim 2, wherein said distal part A and said proximal part B are joined by an internal thread that is formed between a threaded nipple on the distal end of said proximal part B and a threaded navel on the proximal end of said distal part A;

wherein said internal thread is threaded such that the junction is tightened when the screw is advanced; and

wherein coupling of said distal part A and said proximal part B via said internal thread forms a hollow chamber for delivery of said bioactive materials.

4. The polyporous hollow bone screw according to claim 2, wherein said bone screw includes a screw tip that is tapered or fluke-shaped.

5. The polyporous hollow bone screw according to claim 2, wherein the outside of said distal part A comprises cortical or cancellous thread and outside of said proximal part B has no thread.

6. The polyporous hollow bone screw according to claim 5, wherein said distal part A has a distal section and a proximal section, the cortical or cancellous thread being disposed only on the distal section and no thread being disposed on the proximal section, thereby forming an unthreaded middle shaft between said distal part A and said proximal part B.

7. The polyporous hollow bone screw according to claim 6, wherein said middle shaft has the same diameter as the shaft of said proximal part B.

8. The polyporous hollow bone screw according to claim 1, wherein the internal diameter of said hollow chamber is about ⅓

to ⅔

the outer diameter of the screw.

9. The polyporous hollow bone screw according to claim 1, wherein the screw includes an enlarged screw head with a hexagonal recess at the proximal end of the screw head.

10. The polyporous hollow bone screw according to claim 1, wherein said biodegradable core matrix comprises gelatin nanoparticles pre-impregnated with a growth factor selected from the group consisting of BMP-2, BMP-7, and MMP-12.

11. The polyporous hollow bone screw according to claim 1, wherein said biodegradable core matrix comprises fibril sealant dispersed with:

a) a growth factor selected from the group consisting of BMP-2, BMP-7, and MMP-12; and

/or b) bone marrow stem cells.

12. The polyporous hollow bone screw according to claim 11, wherein said fibril sealant comprises pooled fibrinogen and thrombin, wherein when the fibrinogen and thrombin are mixed, said fibrinogen is converted to fibril monomers which spontaneously aggregate to form a fibril clot, and wherein the aggregate is cross-linked via Factor Xllla.

13. The polyporous hollow bone screw according to claim 1, wherein said biodegradable core matrix comprises chitosan nanoparticles dispersed with:

a) a growth factor selected from the group consisting of BMP-2, BMP-7, and MMP-12; and

/or b) bone marrow stem cells.

14. The polyporous hollow bone screw according to claim 13, wherein each of said chitosan nanoparticles comprises a first component comprising said bioactive materials, a second component of low molecule weight chitosan, and a third component comprising a negatively charged organic compound, wherein said second component dominates on a surface of said nanoparticle, and wherein said negatively charged organic compound is complexed with a substantial portion of said low molecular weight chitosan.

15. The polyporous hollow bone screw according to claim 1, further comprising VEGF.