WO2007100769A2

WO2007100769A2 - Lockable wire and cannula assembly

Info

Publication number: WO2007100769A2
Application number: PCT/US2007/004941
Authority: WO
Inventors: Jack White; David Stephens; Wayne Black
Original assignee: Cp Medical Corporation
Priority date: 2006-02-24
Filing date: 2007-02-26
Publication date: 2007-09-07
Also published as: WO2007100769A3

Abstract

A wire probe and locking assembly including a cannula, a locking assembly attached to the cannula, and a wire probe disposed in an axial bore extending through the locking assembly and the cannula. The locking assembly includes engageable elliptical surfaces that can be positioned relative to each other to clamp the wire probe against axial movement.

Description

LOCKABLE WIRE AND CANNULA ASSEMBLY Background of the Invention

This invention relates to a device for precisely positioning a wire probe at a desired location prior to a surgical or diagnostic procedure, and in particular, to a cannula needle and probe wire assembly in which the probe wire can be inserted through the cannula into the body of a patient, and once in position, locked into place.

In the surgical removal of breast lesions, a probe wire is often used to precisely mark the location of non-palpable breast lesion. A cannula is surgically inserted until its tip is in the general vicinity of the lesion. A probe wire having a curved hook on the end

is then inserted through the cannula to position the curved end of the wire as closely as possible to the lesion. A mammogram is taken to view the location of the probe wire, which is then repositioned if necessary. Once the probe wire is positioned satisfactorily, it is locked into place in the cannula, and the cannula is taped into place in preparation for the surgical procedure to remove the lesion.

The prior art includes several cannula/probe wire designs that provide for locking the probe wire into place in the cannula. U.S. Patent No. 5,423,426 discloses a lesion marking device having a helically wound coil of wire attached to an end of the shaft, and which is insertable into the body through a cannula for anchoring the marking device into

a lesion or tumor. A second helical wire may be provided on the shaft which cooperates with a wire guide device attached to the needle to enable the physician to determine the depth of the marking device as it anchors into the lesion.

U.S. Patent No. 5,011 ,473 to Gatturna discloses a wire probe unit having a cannula and a wire hub unit engageable with the cannula. The wire hub unit includes a set of tapered clamping fingers surrounding the probe wire. A threaded cap having a tapered socket is placed over the tapered clamping fingers and is threaded onto the wire hub. Once the probe wire is in position the clamping fingers are clamped around the probe wire by tightening the threaded cap onto the wire hub. The assembly is complex and expensive to manufacture, and clamping of the probe wire requires more manipulation of the threaded cap than is preferable in a surgical setting.

In another known design disclosed in U.S. Patent No. 4,616,656 the probe wire is secured in position by use of a set screw threaded into a portion of the cannula assembly. The set screw can deform the probe wire if over- tightened, and adversely affect the utility of the probe wire if it must be repositioned.

A need therefore remains for a probe wire assembly that permits easy movement of a probe wire through the cannula and in which the probe wire can be readily and easily clamped against axial movement without deforming the probe wire. Summary of the Invention

The present invention is embodied in a preferred embodiment of a wire probe assembly that includes a cannula and locking assembly having an axial bore, and a wire probe disposed in the axial bore. The locking assembly includes a lock body and a lock cap rotatably mounted on the lock body. The cannula includes a mounting hub which engages a portion of the lock body to connect the cannula to the lock body.

In one preferred embodiment a pair of spaced-apart flanges extends from the lock body. At least one of the flanges has a peripheral cam surface. The lock cap has a first bore portion adjacent the peripheral cam surface of the flanges. The first bore portion has a first bore radius that is less than a first radius of the peripheral cam surface and a second bore radius that is at least as long as the first radius of the peripheral cam surface. The lock cap is operable to rotate on the lock body to align the lock cap first bore radius with the first flange radius to urge the spaced-apart flanges toward each other and exert a clamping force on the wire probe. In certain preferred embodiments the lock cap is rotated about 90 degrees to clamp the wire probe into place, but the invention is not intended to be so limited.

Stated slightly differently with regard to a first preferred embodiment, the flange assembly includes an elliptical outer surface. The lock body includes a corresponding elliptical bore portion having a minor diameter that is less than the major diameter of the

elliptical peripheral surface of the flange assembly. When the major diameters of the lock cap and the flange assembly are aligned, the wire probe is freely moveable within the assembly. When the lock cap is rotated to move the lock cap bore major diameter out of alignment with the major diameter of the elliptical flange assembly, the flanges are compressed together clamping the wire probe and locking it against axial movement. In a preferred embodiment the lock body and the lock cap include respective surface markings that align with each other when the lock cap is rotated to the second position.

In another preferred embodiment the clamp member is also formed of a resilient

material, but rather than including a pair of spaced-apart flanges, includes an axial bore. The resilient clamp member also includes a peripheral cam surface as described above. This preferred embodiment is otherwise as described above, and rotation of the lock cap relative to the lock body asserts a clamping force on the clamp member and clamps the wire probe into place. These and other features of the invention will now be explained in greater detail by reference to the drawings. Brief Description of the Drawings

Fig. 1 is a side elevational view of a wire probe/cannula assembly according to a preferred embodiment of the invention.

Fig. 2 is a cross-sectional view of the embodiment shown in Fig. 1.

Fig. 2 A is an enlarged portion of the cross-sectional view of the embodiment shown in Fig. 2.

Fig. 3 is a side elevational view of the cannula of the wire probe/cannula assembly shown in Fig. 1.

Fig. 4 is a side cross-sectional view of the locking assembly shown in Fig. 1.

Fig. 5 is a partial perspective view of the embodiment shown in Fig. 1, and showing the lock body inserted into the mounting hub of the cannula (in phantom).

Fig. 6 is an enlarged view a shown in Fig. 5, and with the lock cap (shown in phantom) rotated to clamp the wire between the flanges of the clamp.

Fig. 7 is a partial cutaway view of the perspective view shown in Fig. 6.

Fig. 8 A is a perspective view of the lock cap according to a preferred embodiment- of the invention.

Fig. 8B is a cross-sectional view of the lock cap illustrated in Fig. 8 A.

Fig. 8C is an end view of the lock cap showing the elliptical bore portion.

Fig. 8D is a perspective view of the lock cap according to a preferred embodiment of the invention showing the stop lugs that limit rotation of the lock cap around the lock body. Fig. 9 is a partial cross-sectional view of the lock body and lock cap according to a preferred embodiment.

Fig. 10 is a side elevational view of a typical wire probe as utilized in the

invention. Detailed Description of Preferred Embodiments

Turning now to Fig.'s 1 and 2 a preferred embodiment of the wire probe/cannula

assembly according to the present invention is shown at 10. Assembly 10 includes a cannula 12, a wire probe 13, a locking assembly 15, and a removeable wire cover 17. Referring to Fig. 3, cannula 12 includes a mounting hub 14 and a pointed hollow needle 16. Mounting hub 14 is a generally cylindrical hollow hub. Needle 16 is disposed in one end of the hub as shown. The opposite end of hub 14 includes a threaded portion 19 that engages with a corresponding threaded portion 20 in locking assembly 15 (Fig. 2). In alternative embodiments hub 14 may be provided without a threaded portion, and is mountable in locking assembly 15 by other known methods, such as an interference fit.

Turning now to Fig.'s 4-7, locking assembly 15 includes a lock body 21, a lock cap 22 rotatably mounted on lock body 15, and a central axial bore 24 through which wire probe 13 passes. Lock body 15 includes a tapered front protrusion 28, a central gripping portion 30, and a clamp 32. Tapered front protrusion 28 is sized and shaped to be inserted into a corresponding tapered opening 29 in cannula 12. Lock body 15 also includes a circular flange 33 that receives and resiliently holds hub 14 of cannula 12 (Fig. 2). Clamp 32 extends from the opposite end of lock body 15, and includes an elliptical

outer surface 34 and a transverse central channel 36. (Fig. 6). In this preferred embodiment clamp 32 includes two spaced-apart resilient flanges 35a and 35b. (Fig.'s 4, 6, and^'7). In other embodiments (not shown), clamp 32 can be a single member with a transverse channel rather than being formed with flanges having distal ends.

Referring now additionally to Fig.'s 8A through 8D₃ lock cap 22 is shown in

greater detail. Lock cap 22 is a hollow member having an open front end 36, a central bore 38 and a rear surface 40. Central bore 38 includes an elliptical bore portion 39. Bore portion 39 includes a major diameter 41that is at least a large as the major diameter 45 of elliptical outer surface 34, and a minor bore diameter 43 that is less than the major diameter 45 of elliptical outer surface 34. In one preferred embodiment the minor bore diameter 43 is about 0.020 inches less than the major diameter 45 of elliptical outer surface 34, but the invention is not limited to any specific amount. Those of skill in the art can readily determine an amount of "interference" necessary for a particular embodiment.

The inner surface of front end 36 includes at least one raised flange 42 that resiliently engages a corresponding recess 44 in lock body 21 (Fig. 7). Lock cap 22 is attached to lock body 21 by snapping flange 42 into recess 44. Lock cap 22 is then rotatable on lock body 21 as will be described in greater detail below. Referring to Fig. 7 probe wire 13 passes through the end of lock cap 22, between flanges 35a and 35b, then through axial bore 24 and cannula 12. Probe wire 26 is axially slidable through the needle assembly 10 to position the probe wire in a desired axial position relative to the cannula and locking assembly.

Probe wire 26 can be locked in the desired axial position by operation of the locking assembly. Probe wire 26 is axially slidable when lock cap 22 is rotated to a first position relative to lock body 15 (Fig. 5), and locked in position when lock cap 22 is rotated to a second position relative to lock body 15 (Fig. 6). In the first position the respective long axes of elliptical bore of lock cap 22 and of the split elliptical flanges 32 are aligned. When so positioned, the central channel 36 is spread and probe wire 26 is freely slidable through the channel. Once the probe wire is in the desired position, lock

cap 26 is rotated around lock body 21 toward a second position where the long axes of elliptical bore of lock cap 22 is no longer parallel with and may be perpendicular to the long axis of the split elliptical flange 32. The rotation of the lock cap 22 as described exerts a clamping force on the split elliptical flange 32 and clamps probe wire 13 in place.

Referring to FIG.'s 8D - 8F, in a preferred embodiment the rotation of lock cap 24 about lock body 22 is limited by lugs 82 in lock body 22 and lugs 84 in lock cap 24. Lugs 82 and 84 are positioned to limit the rotational position of lock cap 22 relative to lock body 22 as it is rotated from the clamped to undamped position and back.

In other embodiments mentioned above, clamp 32 could be a single member having an axial bore extending through clamp 32 and lock body 21 rather than a transverse channel. In this embodiment, clamp 32 includes a peripheral outer surface as described above, and which squeezes a portion of the axial bore to clamp probe wire 13 in place as lock cap 22 is rotated around lock body 21 as described in the foregoing paragraph.

The invention as described above is preferably manufactured of a polymeric material by well-known molding processes, other than, the wire probe which is preferably formed of a metallic material. In either instance the invention is not limited to any specific material of construction, and is intended to include any suitable material now known or which is later developed. In addition, the invention is not intended to be limited to any particular form of medical procedure, and while described in that context, is suitable for any application which would benefit from having an elongate member lockable in an axial position in a locking assembly.

Although the invention has been described by reference to the foregoing preferred embodiments, the description is intended to illustrate the invention rather than to limit its scope. Those of skill in the art will appreciate that the invention as described could be modified in detail and arrangement without departing from the scope of the invention.

Claims

CLAIMS:

1. A wire probe assembly comprising:

a cannula and locking assembly defining an axial bore, and a wire probe disposed

in the axial bore; the locking assembly including a lock body and a lock cap rotatably mounted on the lock body; a pair of spaced-apart flanges extending from the lock body, at least one of said flanges having a peripheral cam surface; the lock cap having a first bore portion adjacent the at least one peripheral cam

surface, the first bore portion having a first bore radius that is less than a first radius of the peripheral cam surface and a second bore radius that is at least as long as the first radius of the peripheral cam surface; and, the lock cap operable to rotate on the lock body to align the lock cap first bore radius with the first flange radius to urge the spaced-apart flanges toward each other and exert a clamping force on the wire probe.

2. A wire probe assembly according to claim 1 further comprising the cannula having a mounting hub, and the lock body having a portion removably disposed in the mounting hub.

3. A wire probe assembly according to claim 1 wherein the at least one of said flanges having a peripheral cam surface comprises both flanges having a peripheral cam surface.

4. A wire probe assembly according to claim 1 wherein the at least one of said peripheral cam surface comprises an elliptical surface portion.

5. A wire probe assembly according to claim 3 wherein the at least one of said flanges having a peripheral cam surface comprises each of said flanges having an

elliptical surface portion.

6. A wire probe assembly according to claim 1 wherein the lock cap rotates about 90 degrees to align the lock cap first bore radius with the first flange radius.

7. A wire probe assembly according to claim 1 wherein one of said pair of flanges is movable responsive to rotation of the lock cap.

8. A wire probe assembly according to claim 1 wherein each of said pair of flanges is movable responsive to rotation of the lock cap.

9. A wire probe assembly according to claim 1 wherein the lock body and the lock cap include respective surface markings that align with each other when the lock cap is rotated to the second position.

10. A wire probe assembly according to claim 1 wherein the lock cap first bore portion is elliptical.

11. A wire probe assembly comprising: a cannula and a locking assembly defining an axial bore, and a wire probe having a portion disposed in the axial bore; the locking assembly including a lock body and a lock cap rotatably mounted on the lock body; a clamp extending from the lock body and including a pair of resilient flanges, the clamp having an elliptical peripheral surface having a major diameter, a smaller minor diameter, and a transverse channel between the flanges; the lock cap having an elliptical bore adjacent the clamp member, the elliptical bore having a minor diameter that is smaller than the major diameter of the elliptical peripheral surface of the clamp; and, the lock cap rotatable to rotate the elliptical bore minor diameter toward the major diameter of the clamp to urge the resilient flanges toward each other and clamp the wire probe between the flanges.

12. A wire probe assembly comprising: a cannula and locking assembly defining an axial bore, and a wire probe disposed in the axial bore; the locking assembly including a lock body and a lock cap rotatably mounted on the lock body; a resilient clamp member extending from the lock body and including an axial bore and having a peripheral cam surface; the lock cap having a first non-circular bore portion adjacent the at least one peripheral cam surface, the first bore portion having a first bore diameter that is less than a first diameter of the peripheral cam surface and a second bore diameter that is at least as long as the first diameter of the peripheral cam surface; and, the lock cap operable to rotate on the lock body to align the lock cap first bore diameter with the first diameter of the peripheral cam surface to squeeze the axial bore into clamping engagement with the wire probe.

13. A wire probe assembly comprising: a cannula and locking assembly defining an axial bore, and a wire probe disposed in the axial bore;

the locking assembly including a lock body and a lock cap rotatably mounted on the lock body; a resilient clamp member extending from the lock body and including an axial bore and having a raised resilient peripheral surface portion; the lock cap having a first non-circular bore portion adjacent the at least one peripheral cam surface, the first bore portion having a first bore diameter that is less than a first diameter of the raised resilient peripheral clamp surface and a second bore diameter that is at least as long as the first diameter of the peripheral cam surface; and,

the lock cap operable to rotate on the lock body to align the lock cap first bore diameter with the first diameter of the raised resilient peripheral clamp surface to squeeze the axial bore into clamping engagement with the wire probe.