Safety reset key and needle assembly

[0001] This invention relates generally to needle assemblies and more particularly to needle assemblies that have shields to cover sharp ends of needles.

[0002] Needle assemblies of the present invention have particular, although not exclusive application in the field of medicine and have needles with sharpened ends for use in piercing the skin to withdraw materials as needed. The needle is supported by some other structure that is used to manipulate the needle. The most common example is a syringe. However, some needle assemblies require the application of substantial force in use. One example of such a needle assembly is a bone marrow needle assembly that is used to penetrate cortical bone to reach the intramedullary canal for withdrawing liquid or a biopsy sample of bore marrow, or for infusing the canal with a selected material. Typically, the needle includes a cannula and a stylet that is received in the cannula and has a hard, sharp tip that can penetrate cortical bone. The tip projects out from the distal end of the cannula. The stylet can be withdrawn from the cannula after the needle penetrates the bone so that the hollow interior of the cannula can be used as a conduit for liquid or a receptacle to collect bone marrow.

[0003] In order to penetrate cortical bone, a substantial amount of force must be applied to the needle. For this reason, bone needle assemblies conventionally mount the needle in a handle that is sized and shaped so that the technician may comfortably grip the handle and apply the force necessary to penetrate the bone. The handle may comprise two handle members that can be selectively put together and separated for inserting the stylet into the cannula and removing the stylet from the cannula. A proximal handle member mounts the stylet and a distal handle member mounts the cannula. “Proximal” and “distal” refer to the relative location of the handle members to the technician when the needle assembly is in use. The proximal handle member is in contact with the palm of the technician's hand in use, and the distal handle member is on the opposite side of the proximal handle member from the palm.

[0004] Some needle assemblies, including bone needle assemblies, have associated safety mechanisms that shield the sharp tips of the needle components when they are not needed and after they have become contaminated with potentially hazardous biological material. The safety mechanism includes a shield and usually a mechanism for locking the shield in place over the sharpened tip. As a matter of convenience, and to enhance the probability that the safety feature will be used by a medical technician, the safety feature may be secured to the needle assembly. However, the safety feature must be retained out of the way when the needle assembly is being used, for example, to collect a liquid or solid sample from the intramedullary canal. The safety feature then must be released from its stowed position and moved to an operative position in which its shield covers the sharpened tip of the needle.

[0005] In cases where a sample (e.g., a bone marrow sample) is collected by the needle assembly, the sample has to be removed from the needle assembly. An obturator is a device including a long thin shaft, and in some cases includes a blunt tip, that can fit inside the cannula for pushing the sample of bone marrow out of the cannula. This can be done with the safety shield in position covering the sharp end of the cannula to protect the technician. In some cases it will be determined that the sample is not satisfactory and it will be necessary to obtain a second sample. It is not necessary to use a new needle assembly, because the needle assembly would be reused on the same patient. However, the shield is held in place over the tip of the needle assembly making it unusable for a collecting a second sample. Accordingly, there is a need for a needle assembly that can be easily reset for second use, but which will not result in inadvertent release of the safety shield.

[0006] In one aspect of the present invention, a needle assembly generally comprises mounting structure and a needle mounted on the mounting structure and extending outwardly therefrom. The needle has a longitudinal axis, a sharp end and a central axial passageway. A safety shield associated with the needle comprises a tubular housing adapted for movement relative to the needle between a stowed position in which the tubular housing is spaced from the sharp end of the needle and a deployed position in which the tubular housing covers the sharp end. A locking mechanism is adapted to releasably lock the tubular housing in position covering the sharp end of the needle. The tubular housing has distal and proximal ends and at least one peripheral slot extending radially inwardly from the periphery and axially along the housing from the distal end of the housing. A reset key adapted to actuate release of the locking mechanism to permit the shield to be moved relative to the needle comprises a support and at least one rib on the support sized and arranged for reception in the peripheral slot of the tubular housing for entering the tubular housing to actuate release of the locking mechanism.

[0007] In another aspect of the present invention, a reset key for use in releasing a locking mechanism of a safety shield covering a sharp tip of a needle for movement of the safety shield relative to the needle generally comprises a support defining a central open space sized and shaped for receiving at least a portion of the safety shield. Ribs mounted on the support and located at positions spaced circumferentially of each other generally around the perimeter of the central open space are shaped and arranged for reception in slots on the safety shield when the safety shield is received in the central open space for actuating release of the locking mechanism.

[0008] In yet another aspect of the present invention, a reset key for use in releasing a locking mechanism of a safety shield covering a sharp tip of a needle for movement of the safety shield relative to the needle generally comprises a shroud sized and shaped for receiving at least a majority of the safety shield therein. A reset member associated with the shroud can actuate release of the locking mechanism when the safety shield is received in the shroud.

[0009] Other objects and features of the present invention will be in part apparent and in part pointed out hereinafter.

[0021] Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

[0022] Referring now to the drawings and in particular to FIG. 1, a medical instrument constructed according to the principles of the present invention is shown in the form of a bone needle assembly, generally indicated at 10. The bone needle assembly includes a handle 12 (broadly, “mounting structure”), a needle 14 and a cannula safety shield 16, all reference numbers indicating their subjects generally. The needle 14 includes a stylet 18 and a cannula 20 that can receive the stylet. The handle 12 includes a first or proximal handle member (indicated generally at 22) mounting the stylet 18, and a second or distal handle member (indicated generally at 24) mounting the cannula 20. It will be understood that a needle could include only a single component part, or more than two parts within the scope of the present invention. Similarly, a handle could be a single part or more than two parts. The mounting structure for a needle can be other than a handle without departing from the present invention. The needle assembly 10 further includes an obturator 26, which is described more fully below, that may be used to remove a sample captured in the cannula 20.

[0023] The cannula 20 has a central 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, and 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, and a proximal end portion of the stylet is received in the proximal handle member 22. The stylet 18 can be inserted through the central 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 projects axially outward from the distal tip 28 of the cannula (as shown in FIG. 1). 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.

[0024] 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 42 for receiving the technician's fingers. The form of the handle can be other than described herein without departing from the scope of the present invention. Moreover, needle mounting structure can be other than a handle within the scope of the present invention. The proximal and distal handle members 22, 24 can be connected together in a suitable manner 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.

[0025] The cannula safety shield 16 may be moved to cover the distal tip 28 of the cannula 20 after the needle assembly 10 has been used. The safety shield 16 includes a generally tubular housing 50 and an internal locking mechanism (generally indicated at 52 in FIG. 2) capable of releasably locking the tubular housing in position covering the distal tip 28 of the cannula 20. The tubular housing 50 has a proximal end closer to the handle 12 and a distal end farther away from the handle. A distal end piece of the tubular housing 50 (generally indicated at 54) includes a funnel-shaped distal end surface 56 of the tubular housing 50 and a central aperture 58 generally aligned with the central axial passageway of the cannula 20. Although illustrated as a separately formed part attached to the tubular housing 50, the distal end piece 54 and tubular housing may be formed as a single piece of material. The shape of the distal end surface 56 may be other than described (e.g., lying in a plane perpendicular to the longitudinal axis of the cannula 20) within the scope of the present invention. Three slots 60 located on the periphery of the tubular housing distal end piece 54 each extend radially inwardly from the periphery of the end piece at its distal end and also extend axially along the end piece toward the proximal end of the tubular housing 50. The number of slots and their precise configuration may be other than described without departing from the scope of the present invention. The function of the slots 60 will be described hereinafter. The tubular housing 50 and handle 12 may include structure to secure the tubular housing in a retracted position adjacent the handle when not needed. An example of such structure is shown in co-assigned U.S. application Ser. No. 11/146,173, filed Jun. 6, 2005, the disclosure of which is incorporated herein by reference.

[0026] The locking mechanism 52 inside the safety shield 16 comprises a canting member including a base 62 having a hole and a pair of arms 64 (only one is shown) extending generally axially from the base. The arms 64 are connected together by a U-shaped member 66 at their ends and each has an upwardly (as oriented in the figures) bent tab 68 (only one is shown) projecting axially outward from the end. Before the locking mechanism 52 is activated to lock the tubular housing 50 in position, the ends of the arms 64 ride on the exterior surface of the cannula 20. This holds the canting member so that the base 62 is generally orthogonal so the longitudinal axis of the cannula 20 and the base can move along the cannula (with the safety shield 16), with the cannula sliding substantially unimpeded through the hole in the base. Once the ends of the arms 64 pass the distal tip 28 of the cannula 20, the locking mechanism 52 is constructed so that the ends of the arms move in a generally radial direction toward an opposite side of the longitudinal axis of the cannula 20. This causes the base 62 of the canting member to cant relative to the axis of the cannula 20 so that the hole in the base is no longer orthogonal to the axis of the cannula. As a result, the base 62 at the edge of the hole grippingly engages the cannula 20 to lock the safety shield 16 in place. The locking mechanism 52 further includes angled surfaces 69A, 69B fixed to the tubular housing 50 that can engage the canting member base 62 to keep the canting member in its canted, locking position upon movement of the tubular housing 50 in either direction relative to the cannula 20. It will be understood that a locking mechanism could take on other forms than shown and described without departing from the scope of the present invention.

[0027] The safety shield 16 further includes an annular reset plunger 70 located inside the tubular housing 50 near its distal end. The reset plunger 70 is movable axially relative to the housing 50 toward the proximal end and includes a frustoconically shaped front surface 72 that is engageable with the tabs 68 of the locking mechanism to release the locking mechanism, as will be more fully described hereinafter. A spring 74 engages the reset plunger 70 and biases it toward the distal end of the tubular housing 50. Thus, unless the reset plunger 70 is forcibly moved, it normally does not interfere with the operation of the locking mechanism 52.

[0028] The needle assembly 10 is driven into the bone by grasping the handle 12 and pushing the stylet 18 through the skin, underlying tissue and cortical bone. Once this penetration has been achieved, the stylet 18 is no longer required. The proximal handle member 22 is disconnected from the distal handle member 24 and moved axially away from the distal handle member so that the stylet 18 slides out of the central axial passageway of the cannula 20 while the cannula remains in the bone. In order to collect a sample of bone marrow, the distal handle member 24 is advanced further into the bone. The sharp tip 28 of the cannula 20 cuts into the bone marrow and a sample is received in the central axial passageway of the cannula. The cannula 20 can then be withdrawn from the patient by pulling on the distal handle member 24. The sample remains lodged in the central axial passageway of the cannula 20 near the sharp tip 28. It will be understood that a needle assembly may be used to collect a sample other than of bone marrow within the scope of the present invention. Moreover, it is not necessary that a cannula be used to collect any sample. For instance, the cannula could also be used to withdraw or infuse fluid.

[0029] The obturator 26 is used to remove a lodged sample of bone marrow that has been collected in the central axial passageway of cannula 20. The obturator 26 includes a grip 78 and a long, thin shaft 80 extending from the grip that is sized to be received in the central axial passageway of the cannula 20 in generally close fitting relation therein. The grip 78 is sized and shaped to be grasped by a user (e.g., between the thumb and pointer finger) for manipulating the obturator 26, as will be described. As shown best in FIGS. 6 and 7, a reset key, generally indicated 82, extends from the grip 78 in the same direction as the shaft 80, and as illustrated is formed as one piece of material with the grip. In the illustrated embodiment, the reset key 82 comprises a tubular shroud 84 (broadly, “a support”) defining a central open space 86 sized and shaped to receive a portion of the tubular housing 50 therein. Although shown as a solid tubular piece of material with an open end, the shroud 84 need not be solid around its circumference within the scope of the present invention. Three elongate ribs 88 formed on an inner wall 90 of the tubular shroud 84 extend generally parallel to the axis of the shroud and are arranged for reception in the slots 60 of the tubular housing 50 as will be described. It will be appreciated that a reset key (not shown) may not be part of an obturator (i.e., the reset key would not include a shaft like shaft 80) without departing from the scope of the present invention.

[0030] FIG. 2 illustrates the initial position of the obturator 26 with the shaft 80 entering the distal end of the tubular housing 50. The free end of the shaft 80 has not yet entered the central axial passageway of the cannula 20 or the aperture 58 of the distal end piece 54. The funnel-shaped surface 56 of the distal end piece 54 guides the shaft 80 toward the aperture 58 that is aligned with the central axial passageway of the cannula 20, thereby facilitating reception of the shaft in the passageway. The grip 78 is pushed to advance the shaft 80 through the aperture 58 in the funnel-shaped surface 56 and into the central axial passageway, which pushes the sample toward the proximal end of the central axial passageway. The shaft 80 is advanced until it protrudes out of the proximal end of the central axial passageway, thereby pushing the sample (not shown) out of the cannula 20 where it can be collected in a Petri dish or other suitable container. The relative location of the tubular shroud 84 and safety shield 16 are in this position are illustrated in FIG. 3. As the shaft 80 is advanced, it slides through the aperture 58 in the distal end piece 54. The locking mechanism 52 remains engaged so that the safety shield 16 does not move and the sharp tip 28 remains covered.

[0031] The technician may observe the sample ejected from the central axial passageway of the cannula 20. If it is determined that the sample is satisfactory, the obturator 26 can be pulled so that the shaft 80 slides back through and out of the cannula 20. The needle assembly 10 can be discarded, or possibly but less likely, cleaned and sterilized for a subsequent use. If the sample is not satisfactory, however, it will be necessary to obtain a second sample from the same patient. This can be done using the same needle assembly 10, but the tubular housing 50 is locked in place by the locking mechanism 52 over the sharp tip 28 of the cannula 20. The tubular housing 50 needs to be moved away from the tip 28 before the needle assembly 10 can be used to obtain a second sample.

[0032] The obturator 26 of the present invention is particularly adapted to permit the safety shield 16 to be released and moved back from the sharp tip 28 of the cannula 20. It should be understood, however, that a device other than an obturator 26 incorporating the resetting, or unlocking, features of the obturator described herein, but not functioning as an obturator, is also contemplated as within the scope of the present invention. From the position shown in FIG. 3, the grip 78 can be advanced toward the tubular housing 50 so that the ribs 88 are received into the corresponding peripheral slots 60 in the tubular housing 50. It will be necessary to align the ribs 88 with corresponding ones of the slots 60 before the ribs may enter the slots. The slots 60 and ribs 88 may be shaped and/or arranged to make this easier or harder to accomplish as desired. In the illustrated embodiment, the three slots 60 and three ribs 88 are all the same size and shape and located at 120 degree intervals. This arrangement makes it relatively easy to align the obturator 26 and safety shield 16 so that the ribs 88 will be received in the slots 60. However, as stated previously, other arrangements and configurations are envisioned. For example and without limiting the breadth of the present disclosure, the slots 60 and ribs 88 can be arranged at unequal intervals. Moreover, the slots 60 and ribs 88 may have different sizes so that the ribs will be received in the slots in only one relative orientation of the obturator 26 and the safety shield 16. Those of ordinary skill in the art will appreciate other possible configurations and/or arrangements. The bias of the spring 74 resists further advancement of the ribs 88 and hence of the obturator 26. This provides a tactile signal to the technician that the obturator shaft 80 has been inserted far enough into the central axial passageway of the cannula 20 to remove the sample, and that further insertion will result in release of the locking mechanism 52.

[0033] If the safety shield 16 is to be reset to expose the sharp tip 28 of the cannula 28, the grip 78 can be advanced toward the tubular housing 50 so that the ribs 88 move into the slots 60 and push the reset plunger 70 against the bias of the spring 74 axially toward the proximal end of the tubular housing 50. The front surface 72 of the reset plunger 70 engages the tabs 68 of the canting member moving the arms 64 back to a position more nearly parallel to the longitudinal axis of the cannula 20. This moves the base 62 of the canting member to a position substantially orthogonal to the longitudinal axis of the cannula 20 so that the cannula can once again slide freely through the hole in the base (FIG. 4). The locking mechanism 52 is thereby released. Thus as shown in FIG. 5, the tubular housing 50 can be grasped to pull back the safety shield 16 toward the distal housing member 24 so that the sharp tip 28 of the cannula 20 is once again exposed. The obturator shaft 80 can be removed and the stylet 18 can be reinserted into the cannula 20 for a second collection of a sample. When the ribs 88 move back out of the slots 60, the spring 74 moves the reset plunger 70 back toward the distal end of the tubular housing 50 so that the locking mechanism 52 is again free to operate for locking the safety shield 16 over the sharp tip 28 of the cannula 20.

[0034] Referring now to FIGS. 9 and 10, a needle assembly of a second embodiment is shown. Parts of the needle assembly of the second embodiment are given the same reference numerals as the corresponding parts of the needle assembly of the first embodiment, plus “100”. A safety shield 116 may have substantially the same construction as the safety shield 16. In particular, the shield 116 includes a tubular housing 150 having peripheral slots 160, as in the first embodiment. An obturator 126 and reset key 182 also have similar constructions (e.g., including ribs 188) as in the first embodiment. However, a tubular shroud 184 of the second embodiment has a length which is sufficiently great so that a central open space 186 of the shroud can receive substantially the entire tubular housing 150. Preferably at least a majority of the tubular housing 150 is received in the open space 186 of the shroud 184. The operation of ribs 188 associated with the tubular shroud 184 to release a locking mechanism 152 may be as described for the first embodiment. However by receiving tubular housing 150 in the central open space 186 of the shroud 184, the tubular housing is shielded from being inadvertently grasped as the obturator is pulled away from the safety shield so that the safety shield 116 is not unintentionally pulled off of the cannula 20. As best seen in FIG. 11, the peripheral edge of a distal end piece 154 of the tubular housing 150 is shaped to include edge segments 192 arranged at converging angles to funnel the ribs 188 into the slots 160 when the ribs engage the distal end piece. Because the ribs 188 are located deep inside the tubular shroud 184 at the bottom of the open space 186, alignment of the ribs with the slots 160 could be difficult. However, the shaped peripheral edge segments 192 engage the ribs 188 and urge the rotation of the obturator 126 to properly orient the reset key 182 so that the ribs move into the slots 160.

[0035] 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.

[0036] 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.