NZ754560A - A pedicle screw tool - Google Patents

Abstract

Problems targeted include causing soft tissue damage when turning pedicle screws in difficult positions to access, and not always being able to know the pedicle screw system at time of surgery. According to one aspect of the invention there is provided a pedicle screw tool comprising a shaft; a handle that can be gripped and turned by hand to cause the shaft to turn; a yoke at an end of the shaft; and a pin supported in the yoke such that it can turn on an axis that is substantially at right angles to the shaft; the tool being formed such that: the pin is adapted to be inserted into a tulip of a pedicle screw; and with the pin in the tulip the shaft can be tilted with respect to the pin and then turned to cause the pedicle screw to screw into or out of bone, depending on the direction that the shaft is turned.

Description

TITLE A Pedicle Screw Tool FIELD OF THE INVENTION A preferred form of the invention relates to a tool for screwing pedicle screws into or out of bone.

BACKGROUND In spinal surgery, it is not always the case that the screw heads or tulips of pedicle screws will be easily accessible such that the screw can be readily screwed into, or unscrewed from, the bone of a patient. A problem is that when the pedicle screw head or tulip is more difficulty positioned, such as deep in the patient’s back or oriented at an awkward angle, there is a risk, when screwing or unscrewing the screw, of causing significant soft tissue disruption to the patient.

Additionally, it is not always the case that the type of pedicle screw system being dealt with will be known at the time of surgery. There are many different types of screw systems that have been used and these vary in the type of screw removal means required e.g. different types and/or sizes of screw drivers. As a result, the surgeon may not have the correct tool on hand at the time of surgery. There is therefore a need for a more universal pedicle screw tool which can remove pedicle screws of any of these systems. For example, by instead applying a turning force directly to the tulip of the pedicle screw in order to turn the screw.

OBJECT OF THE INVENTION It is accordingly an object of preferred embodiments of the invention to go at least some way towards addressing the above problem. While this object applies to preferred embodiments, it should not be seen as a limitation on claims expressed more broadly. The object of the invention per se is simply to provide the public with a useful choice.

DEFINITIONS The term “comprising” if and when used in this document in relation to a combination of features should not be seen as excluding the option of additional unspecified features or steps. In other words, the term should not be interpreted in a limiting way.

SUMMARY OF THE INVENTION According to one aspect of the invention there is provided a pedicle screw tool comprising:  a shaft;  a handle that can be gripped and turned by hand to cause the shaft to turn;  a yoke at an end of the shaft; and  a pin supported in the yoke such that it can turn on an axis that is substantially at right angles to the shaft; the tool being formed such that: o the pin is adapted to be inserted into a tulip of a pedicle screw; and o with the pin in the tulip the shaft can be tilted with respect to the pin and then turned to cause the pedicle screw to screw into or out of bone, depending on the direction that the shaft is turned.

Optionally, the handle is generally T-shaped.

Optionally, the pedicle screw tool is engaged with the pedicle screw, such that a threaded shaft of the screw is substantially parallel to the shaft of the tool and the tulip extends between these shafts but is not co-linear with either.

Optionally, the tulip is angled between said shafts.

Optionally, the tool’s pin bears against the tulip to cause the tulip to be locked with respect to the screw’s shaft.

Optionally, the screw has a substantially spherical head and the tulip is able to rotate about the head when not locked.

Optionally, the screw comprises a grooved insert within the tulip and wherein the tool’s pin is engaged with the groove of said insert.

Optionally, the pedicle screw tool is substantially as herein described with reference to the accompanying drawings.

DRAWINGS Some preferred embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, of which: Figure 1 is a front view of a pedicle screw; Figure 2 is a side view of the screw when disassembled; Figure 3 is an isometric view of a pedicle screw tool; Figure 4 is an isometric view of a pin and yoke assembly forming part of the tool; Figure 5 is a side view of the tool when engaged with the pedicle screw, and the screw being driven into bone; Figure 6 is an alternative side view of the tool when engaged with the screw.

DETAILED DESCRIPTION As shown in Figures 1 and 2 the pedicle screw 1 comprises a pointed tip 2 for boring into bone, an elongate threaded shaft 3, a generally spherical head 4, a tulip 5, a grooved insert 6 and a grub screw 7. The tulip 5 is free to rotate around or pivot on the spherical head 4 such that it can be angled relative to the screw’s shaft 3.

However, the tulip 5 can be locked with respect to the spherical head 4 by turning the grub screw 7 into the grooved insert 6, for example so as to screw down on a pin when located in the grooved insert 6 within the tulip 5. To facilitate this, the inside walls of the tulip 5 have a thread complementary to the grub screw 7. When the tulip is locked in this way, a turning force on the tulip 5 will cause the threaded shaft 3 to turn, so as to advance the screw 1 into or back it out of the bone, depending on which direction the screw 1 is turned.

The ability of the tulip 5 to be set to different angles with respect to the threaded shaft 3 is helpful. This is because, for example in spinal surgery, it is sometimes necessary to align several pedicle screws in bone and place a single bar across the tulips of each of them. When so aligned the bar can be engaged with the tulips simultaneously.

Referring to Figure 3 the pedicle screw tool 8 comprises a generally T-shaped handle 9, a shaft 10 and a yoke 11 that supports a pin 12. The yoke may or may not be integral with the shaft 10. As shown, the longitudinal axis of the pin 12 is substantially perpendicular to the longitudinal axis of the tool’s shaft 10. The yoke 11, which is rigid with respect to the shaft 10, can pivot about the pin 12 so that the shaft 10 can effectively also pivot about the pin 12.

Referring to Figure 4, the tool’s pin 12 is adapted for insertion into the tulip 5 of the pedicle screw 1, where it can be subsequently locked into place by screwing the grub screw 7 into the tulip 5 and down onto the pin 12. The pressure exerted by the grub screw 7 locks the tulip 5 with respect to the rest of the screw 1. As the tool’s yoke 11 can pivot on the tool’s pin 12, the tool 8 can be pivoted as desired with respect to the pedicle screw 1. In this relationship, the tool 8 is locked to the screw 1 but is still able to be angle adjusted with respect to the screw 1.

Referring to Figure 5, with the tool 8 and screw 1 engaged as above, the tool’s handle 9 can be turned by hand to drive the screw 1 into or out of the bone 13 of the patient 14. In the case of figure 5, the tool 8 and the screw 1 are co-linear. In this instance the tulip 5 is not in a tilted disposition.

As shown in Figure 6, if necessary, the tulip 5 can be engaged in a similar manner to that described above when in a tilted disposition. In this case the shaft 3 of the screw 1 is parallel to the shaft 10 of the tool 8. This enables the tool 8 to be rotated to insert or remove the screw 1 even when the tool 8 cannot be made co-linear with the screw 1. In some embodiments, the tulip 5 may be locked at an angle with respect to the shaft 3 of the screw 1 even when the bar is removed. In that instance, the tool 8 can be used to remove the screw 1 in essentially the same manner described in Figure 6.

An advantage of being able to use the tool 8 when in parallel with the screw 1 is that the turning motion of the tool 8 is in many cases less likely to interfere with and wound tissue around the screw 1.

In terms of disclosure, any feature mentioned in this document may be combined with one or more other features mentioned in the document and such combinations may be in any permutation. This applies regardless of whether such combinations have been claimed.

While some preferred embodiments of the invention have been described by way of example it should be appreciated that modifications and improvements can occur without departing from the scope of the following claims.

Claims (8)

1. A pedicle screw tool comprising: 5  a shaft;  a handle portion that can be gripped and turned by hand to cause the shaft to turn;  a yoke at an end of the shaft; and  a pin supported in the yoke such that it can turn on an axis that is 10 substantially perpendicular to the shaft; the tool being formed such that: o the pin is adapted to be inserted into a tulip of a pedicle screw; o with the pin in the tulip the shaft can be tilted with respect to the 15 pin and turned to cause the pedicle screw to move into or out of bone, depending on the direction that the shaft is turned.

2. The pedicle screw tool according to claim 1, wherein the handle is generally T-shaped.

3. The pedicle screw tool according to claim 1 or 2, when engaged with the pedicle screw referred to in claim 1, such that a threaded shaft of the screw is substantially parallel to the shaft of the tool and the tulip extends between these shafts but is not co-linear with either.

4. The pedicle screw tool according to claim 3, wherein the tulip is angled between said shafts.

5. The pedicle screw tool according to claim 3 or 4, wherein the tool’s pin bears 30 against the tulip to cause the tulip to be locked with respect to the screw’s shaft.

6. The pedicle screw tool according to claim 3, 4, or 5 wherein the screw has a substantially spherical head and the tulip is able to rotate about the head 35 when not locked.

7. The pedicle screw tool according to any one of claims 3-6, wherein the screw comprises a grooved insert within the tulip and wherein the tool’s pin is engaged with the groove of said insert. 5

8. A pedicle screw tool according to claim 1, substantially as herein described with reference to the accompanying drawings. FIG. 6