# Patent

## Title
Universal bone screw screwdriver

## Abstract

The instant invention is directed to a universal bone screw screwdriver and in particular to a universal screwdriver that permits the removal of screws from bone plates that are manufactured by different manufacturers having distinct characteristics. The universal bone screw screwdriver is adapted to replaceably receive tool bits corresponding to the screw heads of different manufacturers and comprises a torque limiting spring to secure the tool bit to the driver shaft and inhibit over-tightening of the bone screw into the bone or bone plate as the case may be.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims priority to U.S. Provisional Patent Application No. 61/456,746 filed Nov. 12, 2010, entitled UNIVERSAL BONE SCREW SCREWDRIVER, the entire disclosure of which is incorporated herein by reference.


BACKGROUND OF THE INVENTION
1. Field of the Invention
The embodiments of the present invention relate to a universal bone screw screwdriver for use with interchangeable tool bits made by different screw and bone plate manufacturers. More specifically, the invention relates to a universal bone screw screwdriver that allows for the user to select the tool bit that is compatible with the screw that the user is trying to manipulate and further can prevent the user from over-tightening the screw in the bone or the bone plate.
2. Description of Related Art
Heretofore, use of bone screws and bone plates have become a significant aide in the treatment of bone fracture repair. There are numerous manufacturers that supply the plates and bone screws to hospitals and other surgical centers to permit open reduction internal fixation. Although the efficacy of the bone plates and bone screws has been established as a standard of care over many years, certain problems have arisen regarding the after care that may occur with respect thereto. For example, when a patient that has an open reduction internal fixation procedure performed and is suddenly brought to an emergency room for treatment, it is incumbent upon the hospital or treatment facility to have an inventory of each of the screwdrivers necessary to remove each company's particular screws. Because each company uses different types of screws, it is not assured that the hospital or treatment facility will have the correct screwdriver. Further, even if the appropriate screwdriver is available, it is not assured that that there will be time to sterilize the screwdriver for several hours as is required by emergency room protocol.
Accordingly, a universal screwdriver that is suitable for use with the screw heads of each manufacturer of screw and bone plates is desirable.
SUMMARY OF THE INVENTION
Generally speaking, in accordance with the invention, a universal screwdriver capable of removing screws made by different bone screw and plate manufacturers is provided. A driver shaft is adapted to receive interchangeable tool bits that are suitable for use with the screw heads of different manufacturers. A recess is disposed in the driver shaft for receiving a torque limiting spring which will secure the tool bit in the shaft. The torque limiting spring is removable and hence, permits the tool bit to be replaceably removed from the shaft and further, when the tool bit is disposed in the driver shaft the torque limiting spring inhibits over tightening of the bone screws.
Accordingly an object of the instant invention is to provide an improved universal screwdriver for use with the bone screws of many companies.



BRIEF DESCRIPTION OF THE DRAWINGS
In the drawing figures, which are merely illustrative, and wherein like reference characters denote similar elements throughout the several views:
FIG. 1 is a perspective view of the universal screwdriver constructed with a preferred embodiment of the instant invention;
FIG. 2 is a perspective view of the driver shaft and tool bit interface constructed in accordance with the instant invention;
FIG. 3 is an exploded view of the driver shaft, tool bit and torque limiting spring constructed in accordance with the instant invention;
FIG. 4 is an exploded view of the tool bit visible through the;
FIG. 5 is a sectional view of the driver shaft securing a tool bit using the torque limiting spring in accordance with the instant invention;
FIG. 6 is a sectional view showing the manner in which the torque limiting spring is connected to the driver shaft and is used to inhibit over-tightening of the screw in accordance with the instant invention; and
FIG. 7 is an elevational view of an torque limiting spring to be used in accordance with the instant invention.



DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT
Generally speaking, in accordance with the instant invention, a universal screwdriver generally indicated as 10 in FIG. 1 is provided. In the preferred embodiment depicted in FIGS. 1, 2 and 3, the universal screwdriver includes a handle 12, a driver shaft 14, a tool bit 16, a recess 30 and a torque limiting spring 20. With specific references to FIGS. 2, 3 and 4, the tool bit illustrated therein is representative of the type of screws manufactured by numerous different companies, such as Synthes, Ostiomed, Villex, and Stryker as well as other orthopedic device manufacturers.
As illustrated in FIG. 2, the tool bit design will have a unique configuration such as a cruciform or hexagram or other types of configurations and each manufacturer has a tool bit configuration that is unique to the company. These tool bit configurations are designed to mate with a screw and hence, the screwdrivers provided by each company are not suitable for use with the screws of another company. Accordingly, tool bit 16 illustrated in FIGS. 2, 3 and 4, is by way of example only, and is not limiting in any sense to the instant invention.
The driver shaft 14 is connected to the handle 12 as depicted in FIG. 1. One of ordinary skill in the art would appreciate the mechanism by which the driver shaft 14 is connected to the handle.
As illustrated in FIG. 3, a recess 30 is disposed on the driver shaft 14 which can allow the inside of the driver shaft 14 to be externally visible. An elongated opening 22 extends through the driver shaft 14. The shank of the tool bit 16 has a uniformed cross-sectional dimension and is adapted to be received in the opening 22. The shank of the tool bit is inserted into the opening 22 formed in driver shaft 14 and comes to rest at the thrust bearing surface 26 inside the driver shaft 14 as shown in FIG. 5. A slot 28, which includes a flat 29 (as shown in FIG. 4), is provided in each of the tool bits and is brought into alignment with the recess 30 formed in the each shaft on the tool bit. When the shaft of the tool bit is inserted up, into and against the thrust bearing surface 26 so that the tool bit is brought into alignment with the recess 30 in the driver shaft 14, a locking mechanism can be inserted to secure the tool bit within the driver shaft 14.
In the preferred embodiment, the torque limiting spring 20 is the locking mechanism to secure the tool bit into the driver shaft 14 as depicted in FIGS. 3 and 4. One of ordinary skill in the art would appreciate other methods by which the tool bit can be locked into the driver shaft 14.
The preferred dimensions of the torque limiting spring are depicted in FIG. 7, but by no means is limiting in any sense to the instant invention. When the slot 28 of the tool bit is brought into alignment with the recess 30, the torque limiting spring 20 is inserted in the recess 30 to secure the tool bit 16 into the driver shaft 14 and thereby preventing any actual displacement of the tool bit. Removal of the spring to permit replacement of the tool bit is provided by snapping the torque limiting spring 20 on or off thereby permitting the tool bit to be easily removed or attached.
Additionally, in this position, the torque limiting spring 20 will rest against the flat 29 during each rotation of the handle 12 and will inhibit the over-tightening of the screw in the bone or in the plate as the case may be. When the tool bit 16 is engaged with the screw, as the user rotates the handle 12, the tool bit 16 will encounter resistance from turning the screw into the bone or bone plate. As torque is applied to the bone screw, the torque limiting spring 20 will start to be lifted by the flat 29. When the torque applied to the bone screw reaches the pre-set torque value of the torque limiting spring 20, the torque limiting spring 20 will become disengaged from the flat 29. At this point, the driver shaft 14 can continue to be rotated, but the tool bit 16 will have ceased rotating, thus inhibiting a user from over-tightening a screw into the bone or bone plate. The user can select the desired torque limitation by utilizing a torque limiting spring 20 that conforms to the user's needs.
In one embodiment, the torque limiting spring 20 comprises a flat arm 21 flexibly connected on one end to a semicircular arm 23 as depicted in FIG. 7. In another embodiment, the torque limiting spring 20 further comprises a notch 25 on the interior surface where the flat arm 23 is flexibly connected to the semicircular arm 25 as depicted in FIGS. 2, 4, and 6.
In another embodiment, a flush hole 24 may be disposed on the driver shaft 14. The flush hole 24 extends into the thrust bearing surface 26. When a flush hole 24 is provided, the thrust bearing surface 26 does not extend through the entire diameter of the driver shaft 14. Rather the thrust bearing surface 26 extends perpendicularly to the wall of the driver shaft 14 such that the area behind the tool bit 16 is accessible. In this manner, the flush hole 24 permits the area that receives the shaft of the tool bit 16 to be easily autoclaved and cleaned and any bone debris can be removed between usages.
Thus, while there have been shown and described and pointed out novel features of the present invention as applied to preferred embodiments thereof, it will be understood that various omissions and substitutions and changes in the form and details of the disclosed invention may be made by those skilled in the art without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall there between. In particular, this invention should not be construed as being limited to the dimensions, proportions or arrangements disclosed herein.

## Claims

1. An orthopedic universal screwdriver comprising:
a handle;
a driver shaft connectable to said handle that is adapted to receive an interchangeable tool bit for engaging bone screws;
a recess disposed in said driver shaft; and
a torque limiting spring removeably attachable to the driver shaft via said recess for securing the interchangeable tool bit to said driver shaft and configured to prevent rotation of the interchangeable tool bit when said torque limiting spring reaches a pre-set torque value, wherein the torque limiting spring further comprises at least two arms, wherein the first arm is a flat arm and the second arm is a semicircular arm.

2. The orthopedic universal screwdriver of claim 1, wherein the end of the driver shaft adapted to receive the tool bit is hollow.

3. The orthopedic universal screwdriver of claim 1, wherein the torque limiting spring is capable of preventing over tightening of the bone screw.

4. The orthopedic universal screwdriver of claim 1, wherein said torque limiting spring further comprises a notch on an interior surface where the first arm and the second arm connect.

5. The orthopedic universal screwdriver of claim 1, further comprising:
a flat surface on the interchangeable tool bit and configured to align with the recess when said interchangeable tool bit is inserted into said driver shaft and
said torque limiting spring engages the flat.

6. An orthopedic universal screwdriver comprising:
a handle;
a driver shaft connectable to said handle that is adapted to receive an interchangeable tool bit for engaging bone screws;
a recess disposed in said driver shaft;
the interchangeable tool bit having a shank comprising a slot that is configured to correspond to the recess on the driver shaft so that a torque limiting spring is received in the recess and the slot;
wherein the torque limiting spring is removeably attachable to the driver shaft via said recess for securing the interchangeable tool bit to said driver shaft and configured to prevent rotation of the interchangeable tool bit when said torque limiting spring reaches a pre-set torque value.

7. The orthopedic universal screwdriver of claim 6, further comprising a thrust bearing surface within said driver shaft that receives one end of the interchangeable tool bit.

8. The orthopedic universal screwdriver of claim 6, further comprising a flush hole extending to a thrust bearing surface.

9. The orthopedic universal screwdriver of claim 6, wherein when said torque limiting spring reaches a pre-set torque value, the driver shaft is configured to rotate without imparting a rotational force on the interchangeable tool bit.

10. A method of using the orthopedic screwdriver of claim 6, comprising:
inserting an interchangeable tool bit into the driver shaft;
attaching a torque-limiting spring to the driver shaft and securing the tool bit to the driver shaft;
engaging the screwdriver to a bone screw; and
applying a rotational force to at least one of the handle or driver shaft;
rotating the bone screw until a pre-set torque value is reached whereby the torque-limiting spring is automatically disengaged from the driver shaft;
disengaging the screwdriver from the bone screw.