METHOD AND APPARATUS FOR BONE FRACTURE FIXATION

• US 20100179600A1
• Filed: 03/25/2010
• Published: 07/15/2010
• Est. Priority Date: 02/22/2002
• Status: Active Grant

• Current Assignee: Zimmer Biomet CMF and Thoracic, LLC (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Biomet Microfixation LLC (Zimmer Biomet Holdings, Inc.)
• Inventors: Schumacher, Brian S., Duncan, Jeffrey A., Steger, Shon D.
• Granted Patent: US 8,460,345 B2
• Time in Patent Office: Days
• US Class Current: 606/281
• CPC Class Codes: A61B 17/80 Cortical plates , i.e. bone plates; Instruments for holding or positioning cortical plates, or for compressing bones attached to cortical plates
• CPC Class Codes: A61B 17/8047 wherein the additional element surrounds the screw head in the plate hole A61B17/8052 takes precedence
• CPC Class Codes: A61B 17/8052 immobilised relative to screws by interlocking form of the heads and plate holes, e.g. conical or threaded
• CPC Class Codes: A61B 17/8076 for the ribs or the sternum
• CPC Class Codes: A61B 17/8685 comprising multiple separate parts
• CPC Class Codes: A61B 17/8863 Apparatus for shaping or cutting osteosynthesis equipment by medical personnel
• CPC Class Codes: A61B 2017/00004 (bio)absorbable, (bio)resorbable or resorptive

Abstract

A method according to the present disclosure may include determining a load to be supported across separated bone regions by a bridge region of a bone plate. The method may further include determining an acceptable cut force (CF) for the bridge region, determining a cross-sectional area (a) of the bridge region based on the determined load, and determining a height (h) and a width (w) of the bridge region. A bone plate may be provided including a bridge region having the height (h) and width (w) for securing the separated bone regions.

Claims

1. A method comprising:

determining a load to be supported across separated bone regions by a bridge region of a bone plate;

determining an acceptable cut force (CF) for the bridge region;

determining a cross-sectional area (a) of the bridge region based on the determined load;

determining a height (h) and a width (w) of the bridge region based on the following equation;

$\mathrm{CF}=\left(\left(S<br><br><br><br>1\right)<br><br>\left(a\right)+C<br><br><br><br>1\right)<br><br>{\left(\frac{w}{h_{\max }}\right)}^{S<br><br><br><br>2}$

wherein “

S1,”

“

C1,” and

“

S2”

are constants for a given bridge material, constant “

S1”

is a slope of a curve defined by a range of cut force versus cross-sectional area, constant “

C1”

is a Y-intercept of the curve, and constant “

S2”

is a slope of Ln(ARF) versus Ln(aspect ratio), wherein “

ARF”

is an aspect ratio factor that is defined by;

$\mathrm{ARF}=\frac{\mathrm{CF}<br><br><br><br>1}{\left(\mathrm{CF}<br><br><br><br>1+\mathrm{CF}<br><br><br><br>2\right)/2}$

wherein (h_max) is a maximum height of the bridge region, “

CF1”

is a first cut force associated with one of the width (w) and the maximum height (h_max) of the bridge region, “

CF2”

is a second cut force associated with the other of the width (w) and the maximum height (h_max), and the aspect ratio is a ratio between the maximum height (h_max) and the width (w); and

providing a bone plate including a bridge region having the height (h) and width (w) for securing the separated bone regions.

2. The method of claim 1, wherein said determined acceptable cut force (CF) is a maximum allowable cut force for the bridge region.

3. The method of claim 1, further comprising removing the bone plate from a sternum by severing the bridge region with a cutting tool.

4. The method of claim 3, wherein the severing includes cutting along the width (w).

5. The method of claim 3, further comprising securing the plate to the separated bone region, the plate including a first fixation region on a first end of the bridge region and a second fixation region on a second end of the bridge region, the securing including fixing the first fixation region to a first side of the separated bone region and fixing the second fixation region to a second side of the separated bone region.

6. The method of claim 5, wherein the first fixation region includes a hook and the securing includes locating the hook around the first side of the separated bone region.

7. The method of claim 1, further comprising securing the plate to a separated sternum, the plate including a first fixation region on a first end of the bridge region and a second fixation region on a second end of the bridge region, the securing including coupling the first fixation region to a first side of the separated sternum and coupling the second fixation region to a second side of the separated sternum.

8. The method of claim 7, wherein the first fixation region includes a hook and the securing includes locating the hook around the first side of the separated sternum.

9. The method of claim 1, wherein the cross-sectional area (a) is defined by the product of the maximum height (h_max) and the width (w).

10. The method of claim 1, wherein the determined height (h) is less than or equal to the maximum height (h_max).

11. The method of claim 1, wherein the first cut force (CF1) is defined along the width (w).

12. The method of claim 1, wherein the first cut force (CF1) is defined along the height (h).

13. A bone plate comprising:

a first fixation region adapted to secure the bone plate to a first side of a separated bone region;

a second fixation region adapted to secure the bone plate to a second side of the separated bone region; and

a bridge region extending between and coupling said first and second fixation regions to one another, said bridge region defining a cross-sectional area (a) severable by a predetermined maximum allowable cut force (CF) and adapted to support a predetermined load across the separated bone region, said bridge region being defined by;

$\mathrm{CF}=\left(\left(S<br><br><br><br>1\right)<br><br>\left(a\right)+C<br><br><br><br>1\right)<br><br>{\left(\frac{w}{h_{\max }}\right)}^{S<br><br><br><br>2}$

and having a width (w) and a height (h) that is less than or equal to a maximum height (h_max), wherein “

S1,”

“

C1,” and

“

S2”

are constants for a given bridge material, constant “

S1”

is a slope of a curve defined by a range of cut force versus cross-sectional area, constant “

C1”

is a Y-intercept of the curve, and constant “

S2”

being a slope of Ln(ARF) versus Ln(aspect ratio), and “

ARF”

is an aspect ratio factor that is defined by;

$\mathrm{ARF}=\frac{\mathrm{CF}<br><br><br><br>1}{\left(\mathrm{CF}<br><br><br><br>1+\mathrm{CF}<br><br><br><br>2\right)/2}$

wherein “

CF1”

is a first cut force associated with one of the width (w) and the maximum height (h_max) of said bridge region, “

CF2”

is a second cut force associated with the other of the width (w) and the maximum height (h_max), and the aspect ratio is a ratio between the maximum height (h_max) and the width (w).

14. The bone plate of claim 13, wherein said first fixation region includes a hook adapted to extend around the first side of a separated bone region.

15. The bone plate of claim 14, wherein said second fixation region includes a first aperture adapted to receive a first fastener to couple the bone plate to the second side of the separated bone region.

16. The bone plate of claim 15, wherein said first fixation region includes a second aperture located between said bridge region and said hook and adapted to receive a second fastener to couple the bone plate to the second side of the separated bone region.

17. The bone plate of claim 14, wherein said hook is adapted to extend around a first side of a separated sternum.

18. The bone plate of claim 13, wherein the cross-sectional area (a) is defined by the product of the maximum height (h_max) and the width (w).

19. The bone plate of claim 13, wherein the first cut force (CF1) is defined along the width (w).

20. The bone plate of claim 13, wherein the first cut force (CF1) is defined along the height (h).