Needle assembly with removable depth stop
A needle assembly (10) includes a needle (14) attached to mounting structure (12), and is used to insert the needle into the body of a patient. A depth stop unit (50) of the needle assembly provides a stop surface (58) to limit the distance the needle can be inserted into the body. The depth stop unit may include a depth stop (52) that is adjustable to selectively change the depth to which the needle can be inserted. The entire depth stop unit can be removed from the needle assembly to permit the full length of the needle to penetrate into the body.
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This application includes subject matter in common with co-assigned U.S. patent application Ser. No. ______, entitled Bayonet Release of Safety Shield for Needle Tip, filed simultaneously herewith. The subject matter of this application is incorporated herein in its entirety by reference.
BACKGROUND OF THE INVENTIONThis invention relates generally to needles used in medicine and more particularly to a needle assembly having a depth stop to limit penetration of the needle into the subject, which depth stop can be selectively removed from the needle.
In some medical applications needles are used to make relatively deep penetrations into the body in order to perform their tasks. For instance where it is necessary to obtain a biopsy sample, the needle may have to penetrate deep inside tissue to the location from which the sample is to be taken. However, there are also situations where the needle has to penetrate a substantial distance through tissue in order to inject a drug or withdraw fluid. One specific example is that of accessing the intramedullary canal of bone. This may be done to collect a specimen of bone marrow or fluid from the intramedullary canal. It is also possible that a drug or other fluid may be infused into the canal through the needle.
To penetrate the hard cortical bone surrounding the intramedullary canal, the needle must be hard and strong, and substantial force has to be applied to the needle. The needle is typically mounted on a handle that can be grasped by a medical technician to supply the necessary force to penetrate the cortical bone to reach the intramedullary canal. It is important that the medical technician exercise care so that the needle is not driven elsewhere in the body other than the target bone. Depending upon the location of the bone selected for penetration, the bone may be near to organs or blood vessels that could be damaged by a misdirected needle. For example, if the needle penetrates too deeply, it could damage an untargeted area of the body. Thus, the use of a bone needle assembly of this type requires the simultaneous exercise of substantial force and precision.
One way to reduce the chance that the needle will damage the body is to provide a depth stop that limits the depth of penetration of the needle into the body. Typically the depth stop is disposed around the needle below the handle and can engage the exterior of the body to stop the inward thrust of the needle. The depth stop reduces the length of the needle that is available for penetrating into the body. The appropriate depth of penetration can vary widely from one patient to the next. For example, an obese patient may require penetration of several inches of skin and soft tissue to reach the bone, while a thin patient requires very little penetration to reach the bone. Moreover, the location of the target bone may call for a different depth of penetration. To meet this need, depth stop units have been provided that permit the depth stop to be adjusted to expose a greater or lesser length of the needle for penetration into the body. While these adjustable depth stop units provide greater flexibility they do not fully meet the need for variability in needle length. Moreover, some procedures have less reason to use the depth stop than others. Medical technicians differ on their preference for use of needle assemblies incorporating depth stops.
In instances where a depth stop is present in the needle assembly, a substantial length of the needle will never be available for use to penetrate into the body because it will remain covered by the depth stop. This is true even if the depth stop is adjusted to expose the maximum possible length of the needle for penetration. Accordingly, it is necessary to keep on hand multiple needle assemblies having different lengths and/or needle assemblies that do not have depth stops.
SUMMARY OF THE INVENTIONIn one aspect of the present invention, a convertible needle assembly generally comprises a mounting structure and a needle having a longitudinal axis and a sharp end, the needle being mounted on the mounting structure and projecting outwardly from the mounting structure so that the sharp end is generally remote from the mounting structure. A depth stop adapted to limit the depth of penetration of the needle is releasably connected by a rotary connector to the needle assembly. The released depth stop is removable from the needle for increasing the possible depth of penetration of the needle.
In another aspect of the present invention, a bone needle assembly generally comprises a handle and a needle having a longitudinal axis and a sharp end. The needle is mounted on the handle at a location away from the sharp end of the needle and projects outwardly from the handle. A depth stop unit comprises a positioning stem and a depth stop mounted on the position stem and movable along a length of the stem to different selected positions along the stem and along the longitudinal axis of the needle. The depth stop has a stop surface adapted to limit the depth of penetration of the needle. A rotary connector of the depth stop unit is adapted to releasably connect the stem to the needle assembly. The rotary connector is capable of releasing connection of the stem so that the stem and depth stop may be removed from the needle for increasing the possible depth of penetration of the needle.
In still another aspect of the present invention, a method of adjusting a permissible depth of penetration of a needle of a needle assembly generally comprises releasing a rotary connection of a depth stop unit to the needle assembly. The depth stop unit includes a depth stop positioned along a longitudinal axis of the needle and limiting the depth of penetration of the needle to a first depth. The depth stop unit is slid off of the needle to expose an additional length of the needle for penetration of the needle to a second depth greater than the first depth.
Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.
DETAILED DESCRIPTION Referring now to the drawings and in particular to
The cannula 20 has an axial passage extending the length of the cannula and opening at both ends of the cannula. A distal tip 28 of the cannula 20 is beveled and sharpened. A proximal end portion of the cannula 20 is received in the distal handle member 24. The stylet 18 is solid and includes a sharp distal tip 32, and a proximal end portion received in the proximal handle member 22. The stylet 18 can be inserted through the axial passage opening in the proximal end portion of the cannula 20 and received entirely through the axial passage of the cannula so that its sharp distal tip 32 projects axially outward from the distal tip 28 of the cannula. The stylet 18 provides the tool for penetrating the cortical bone, and can be removed from the cannula 20 once the intramedullary canal is accessed by the needle 14.
The handle 12 formed by the proximal and distal handle members 22, 24 has an ergonomic shape that can be comfortably received in a medical technician's hand, and allows the technician to easily control the needle assembly 10 as he or she applies the substantial forces needed to penetrate the bone. More specifically, the top or proximal surface 38 of the proximal handle member 22 is rounded in conformance with the shape of the palm of the hand. The bottom or distal surface 40 of the distal handle member 24 is also rounded but is undulating in shape thereby forming finger wells 40A for receiving the technician's fingers. The proximal and distal handle members 22, 24 can be securely connected together when the stylet 18 is received in the cannula 20, so that the handle 12 acts essentially as a single piece when used to drive the needle 14 through a patient's skin and into the bone. The proximal and distal handle members 22, 24 can be disconnected and moved apart for removing the stylet 18 from the cannula 20.
To assemble the proximal handle member 22 and stylet 18 with the distal handle member 24 and cannula 20, the sharp distal tip 32 of the stylet is inserted into the central open portion of the distal handle member so that it enters the axial passage of the cannula. The proximal and distal handle members are turned from their aligned position to a position in which the proximal handle member 22 is perpendicular to the distal handle member 24 (not shown). When the handle members 22, 24 are fully brought together, they are turned toward alignment with each other. This results in the handle members 22, 24 being interconnected in the position illustrated in
The proximal end portion of the stylet 18 extends into the open center of the proximal handle member 22, and is secured is a suitable manner to the proximal handle member. For instance, the handle member 22 may be molded around the stylet 18 or the stylet may be attached to the proximal handle member by an adhesive. The proximal handle member 22 can be formed of polymeric or other material. Although shown as opaque in the drawings, the handle member 22 could be partially or totally transparent. A proximal end portion of the cannula 20 extends into a tubular, projecting portion 66 of the distal handle member 24 located at its center. The cannula 20 is mounted on the distal handle member 24 in a suitable manner. For instance, the distal handle member 24 may be molded around the cannula 20 or the cannula may be adhered to the distal handle member. The distal handle member 24 can be formed of polymeric or other suitable material. Although shown as opaque, the handle member 24 could be partially or totally transparent.
The needle assembly 10 further comprises a depth stop unit (broadly, “an operative member), generally indicated at 50. The depth stop unit includes a depth stop 52 that has a generally conical portion 54 with a cylindrical nose 56 projecting therefrom, calling to mind roughly the shape of a space capsule. The conical portion 54 has an annular bottom stop surface 58 that is engageable with the body of the patient to limit the penetration depth of the needle 14 into the body. A hub 59 generally in the center of the bottom of the depth stop 52 is sized and shaped to receive and hold a tube (not shown) by a releasable interference fit. The tube covers the sharp ends 28, 32 of the cannula 20 and stylet 32, and is removed by pulling off of the hub 59 prior to usage of the needle assembly 10.
The depth stop unit 50 further includes an elongate, tubular threaded member, indicated generally at 60, on which the depth stop 52 is threadably mounted. The threaded member 60 has an axially extending passage 61 (
As shown in
The adjustment of the depth stop 52 along the length of the threaded member 60 allows considerable variance in the effective length of the needle 14 and selected depth of penetration. However, in some instances it will be necessary or desirable to employ substantially the full length of the needle 14 projecting outward from the tubular portion 66 of the distal handle member 24 to reach the target bone. The depth stop unit 50 can be removed from the needle assembly 10 by disconnecting the threaded member 60 from the distal handle member 24.
The threaded member 60 is attached to the distal handle member 24 by the fingers 70 of the arms 68 being received in circumferentially extending slots 80 formed in a projecting tubular portion (generally indicated at 82) of the distal handle member (see,
When the triangular projections 70A are received in the triangular recesses 80A, the threaded member 60 is held against rotation relative to the tubular portion 82 of the distal handle member 24 (
To release the threaded member 60, and hence the depth stop unit 50 from connection with the distal handle member 24, the connector 66 (and hence the entire threaded member 60) is rotated about 90 degrees in the direction indicated by arrow A3 from its connected position shown in
Once the threaded member 60 is disconnected from the distal handle member 24 by this motion, the depth stop unit 50 can freely slide down the needle 14 and off of its distal end so that the depth stop unit is entirely removed from the needle assembly 10, as is illustrated in
Generally circumferentially extending ribs 88 are located on the depth stop 52 at the intersection of the conical portion 54 and the cylindrical portion 56. It will be understood that ribs (not shown) could be placed at other locations, such as on the arms 68 of the threaded member 60. The ribs 88 are spaced apart axially of each other along the longitudinal axis of the threaded member 60. The wave shape of the ribs 88 suggests by its circumferential extent that removal of the depth stop unit 50 requires rotary motion about the axis of the threaded member 60 and needle 14. The axial extent of the ribs 88 suggests a second movement along the axis is needed. These provide indications to the medical technician of how to release the depth stop unit 50 and then slide it off of the needle assembly.
When introducing elements of the present invention or the preferred embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Moreover, the use of “up”, “down”, “top” and “bottom” and variations of these terms is made for convenience, but does not require any particular orientation of the components.
As various changes could be made in the above without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
Claims
1. A convertible needle assembly (10) comprising:
- a mounting structure (12);
- a needle (14) having a longitudinal axis and a sharp end (28, 32), the needle being mounted on the mounting structure and projecting outwardly from the mounting structure so that the sharp end is generally remote from the mounting structure;
- a depth stop (52) adapted to limit the depth of penetration of the needle;
- a rotary connector (66) adapted to releasably connect the depth stop to the needle assembly, the released depth stop being removable from the needle for increasing the possible depth of penetration of the needle.
2. A convertible needle assembly as set forth in claim 1 wherein the rotary connector (66) is constructed to connect to the mounting structure (12) by making a turn in a first direction about an axis that is less than 360 degrees, and to release from the mounting structure by making a turn in a second direction opposite the first direction about the axis that is less than 360 degrees.
3. A convertible needle assembly as set forth in claim 2 wherein the rotary connector (66) is constructed to connect to the mounting structure (12) and release from the mounting structure by making turns in the first and second directions, respectively, that are less than 180 degrees.
4. A convertible needle assembly as set forth in claim 2 wherein the rotary connector (66) is constructed to connect to the mounting structure (12) and release from the mounting structure by making turns in the first and second directions, respectively, that are about 90 degrees
5. A convertible needle assembly as set forth in claim 4 wherein the rotary connector (66) and mounting structure (12) are constructed for bayonet connection of the rotary connector to the mounting structure.
6. A convertible needle assembly as set forth in claim 5 wherein the mounting structure (12) comprises a pair of slots (80) and the rotary connector includes a pair of fingers (70) adapted to be received in the slots.
7. A convertible needle assembly as set forth in claim 6 wherein at least one of the slots (80) and the fingers (70) includes retention structure (70A, 80A) to resist relative rotation between the rotary connector (66) and the handle (12).
8. A convertible needle assembly as set forth in claim 7 wherein the retention structure comprises a projection (80A) located in the slot (80) and a recess (70A) located on the finger (70), the projection being adapted to snap into the recess to provide a tactile confirmation of engagement.
9. A convertible needle assembly as set forth in claim 1 wherein the rotary connector (66) mounts the depth stop (52) for selective positioning along the length of the needle (14) to change the depth limit of penetration.
10. A convertible needle assembly as set forth in claim 9 wherein the rotary connector (66) is elongate and has threads (64) along its length, the depth stop (52) having threads (76) mated with the threads of the rotary connector and being rotatable on the rotary connector for selective positioning along the length of the needle (14).
11. A convertible needle assembly as set forth in claim 10 wherein the rotary connector (66) and depth stop (52) are conjointly removable from the needle (14).
12. A bone needle assembly (10) comprising:
- a handle (12);
- a needle (14) having a longitudinal axis and a sharp end (28, 32), the needle being mounted on the handle at a location away from the sharp end of the needle and projecting outwardly from the handle;
- a depth stop unit (50) comprising a positioning stem (62), a depth stop (52) mounted on the position stem and movable along a length of the stem to different selected positions along the stem and along the longitudinal axis of the needle, the depth stop having a stop surface (58) adapted to limit the depth of penetration of the needle, and a rotary connector (66) adapted to releasably connect the stem to the needle assembly, the rotary connector being capable of releasing connection of the stem so that the stem and depth stop may be removed from the needle for increasing the possible depth of penetration of the needle.
13. A bone needle assembly as set forth in claim 12 wherein the rotary connector (66) is constructed to connect to the handle (12) by making a turn in a first direction about an axis that is less than 360 degrees, and to release from the handle by making a turn in a second direction opposite the first direction about the axis that is less than 360 degrees.
14. A bone needle assembly as set forth in claim 13 wherein the rotary connector (66) is constructed to connect to the handle (12) and release from the handle by making turns in the first and second directions, respectively, that are about 90 degrees.
15. A bone needle assembly as set forth in claim 14 wherein the handle (12) includes a pair of slots (80) and the rotary connector (66) includes a pair of fingers (70) adapted to be received in the slots.
16. A bone needle assembly as set forth in claim 12 wherein the rotary connector (66) and positioning stem (62) are formed as one piece (60).
17. A bone needle assembly as set forth in claim 16 wherein the positioning stem (62) is elongate and has threads (64) along its length, the depth stop (52) having threads (76) mated with the threads of the positioning stem and being rotatable on the positioning stem for selective positioning along the length of the needle (14).
18. A method of adjusting a permissible depth of penetration of a needle (14) of a needle assembly (10) comprising:
- releasing a rotary connection of a depth stop unit (50) to the needle assembly, the depth stop unit including a depth stop (52) positioned along a longitudinal axis of the needle and limiting the depth of penetration of the needle to a first depth;
- sliding the depth stop unit off of the needle to expose an additional length of the needle for penetration of the needle to a second depth greater than the first depth.
19. A method as set forth in claim 18 wherein the step of releasing connection of the depth stop unit (50) comprises rotating a rotary connector (66) attaching the depth stop unit to the needle assembly (10) less than 360 degrees relative to the needle assembly.
20. A method as set forth in claim 19 wherein the step of releasing the connection of the depth stop unit (50) comprises rotating the rotary connector (66) about 90 degrees relative to the needle assembly (10).
Type: Application
Filed: Jun 6, 2005
Publication Date: Dec 7, 2006
Applicant: Sherwood Services AG (Schaffhausen)
Inventors: Kimberly Moos (Florissant, MO), David Swisher (St. Charles, MO), Whitney Reynolds (Cumberland, RI)
Application Number: 11/145,684
International Classification: A61M 5/00 (20060101);