BIODEGRADABLE, MAGNESIUM-CONTAINING BONE SCREWS, METHODS FOR THEIR PREPARATION AND MEDICAL APPLICATIONS THEREFOR

• US 20140243911A1
• Filed: 02/20/2014
• Published: 08/28/2014
• Est. Priority Date: 02/22/2013
• Status: Active Grant

• Current Assignee: University of Pittsburgh of The Commonwealth System of Higher Education
• Original Assignee: University of Pittsburgh of The Commonwealth System of Higher Education
• Inventors: ALMARZA, ALEJANDRO JOSE, HOLMES, JOHN A., CHUNG, WILLIAM LEE, HENDERSON, SARAH E.
• Granted Patent: US 10,849,667 B2
• Time in Patent Office: Days
• US Class Current: 606/305
• CPC Class Codes: A61B 17/8605 Heads, i.e. proximal ends projecting from bone
• CPC Class Codes: A61B 17/8635 Tips of screws
• CPC Class Codes: A61B 17/866 Material or manufacture
• CPC Class Codes: A61L 31/022 Metals or alloys

Abstract

The invention relates to a biodegradable, magnesium-containing bone screw for implanting into a patient body for use in medical applications, such as, orthopedic, craniofacial and cardiovascular surgery. The bone screw has a head, shaft and tip. The thickness of the head is greater than the thickness of conventional bone screws. The shaft includes both a non-threaded and a threaded portion. The tip is non-threaded and pointed, such as, conical in shape. The composition of the bone screws provide for improved biodegradability and biocompatibility, and the features of the structure of the bone screws facilitate guidance and placement during implantation as well as reduce the potential for mechanical failures.

Claims

1. A biodegradable, magnesium-containing bone screw, comprising:

a head having a top surface, a bottom surface and a thickness extending between the top and bottom surfaces;

a shaft having a first end and a second end and a length linearly extending between the first and second ends, the first end of the shaft coupled to the bottom surface of the head, a portion of the length of the shaft extending from the first end to a transition point being non-threaded and a remaining portion of the length of the shaft extending from the transition point to the second end of the shaft being threaded; and

a non-threaded, pointed tip extending from the second end of the shaft,

wherein the thickness of the head is greater than a conventional bone screw head thickness.

2. The bone screw of claim 1, wherein the top surface of the head has an indentation diametrically formed therein, the indentation having a length and height that is suitable to accommodate a driver mechanism for rotating and guiding the bone screw.

3. The bone screw of claim 2, wherein the length of the indentation extends along an entire or nearly entire diameter of the head.

4. The bone screw of claim 1, wherein the non-threaded portion of the length of the shaft is less than the threaded portion of the length of the shaft.

5. The bone screw of claim 1, wherein the tip is cone shaped.

6. The bone screw of claim 1, wherein said screw is composed of magnesium alloy.

7. The bone screw of claim 1, wherein said screw is employed as an implant device for medical applications.

8. The bone screw of claim 7, wherein said medical applications include craniofacial surgery.

9. A method of preparing a biodegradable, magnesium-containing bone screw, comprising:

(a) preparing a magnesium-containing composition;

(b) melting the magnesium-containing composition at an elevated temperature;

(c) introducing the magnesium-containing composition from step (b) into a mold, the mold comprising;

a head having a top surface, a bottom surface and a thickness extending between the top and bottom surfaces, the thickness of the head being greater than a conventional bone screw head thickness;

a shaft having a first end and a second end and a length linearly extending between the first and second ends, the first end of the shaft coupled to the bottom surface of the head, a portion of the length of the shaft extending from the first end to a transition point being non-threaded and a remaining portion of the length of the shaft extending from the transition point to the second end of the shaft being threaded; and

a non-threaded, pointed tip extending from the second end of the shaft; and

(d) cooling and solidifying the mold.

10. A method of employing a biodegradable screw as a medical device to regenerate new tissue in a patient, comprising:

preparing a magnesium-containing bone screw in accordance with claim 9;

forming an opening in existing tissue in the patient; and

implanting the bone screw into the opening in the existing tissue of the patient.

11. The method of claim 10, wherein the existing tissue is selected from the group consisting of craniofacial bone, orthopedic bone and cardiovascular tissue.