TISSUE-SAMPLING INSTRUMENT AND METHODS OF USE
FIELD
The present invention relates to surgical instruments for obtaining tissue samples.
BACKGROUND In the field of medicine, before effective treatment can be prescribed, physicians normally perform a series of tests to determine the nature of the illness, infection, or disease. Such tests, in many cases, are performed on diseased tissue. This, in fact, requires the physician to obtain a specimen of the infected or diseased tissue in the most efficient manner with the least discomfort to the patient. Various biopsy methods are known for obtaining tissue samples.
Biopsies typically are performed using an open or a closed technique. Open biopsy removes the entire mass (excision biopsy) or a part of the mass (incision biopsy). Closed biopsy is usually performed with a needle-like instrument and may be either an aspiration or a core biopsy. In needle aspiration biopsy, individual cells or clusters of cells are obtained for cytologic examination and may be prepared such as in a Papanicolaou smear. In core biopsy, a core or filament of tissue is obtained for histologic examination. The type of biopsy that is performed depends on the circumstances; however, core biopsy is extremely useful in a number of conditions and is the most widely used type of biopsy. Minimally invasive biopsy instruments are commonly used to obtain tissue specimens for examination to aid in the diagnosis of disease. These types of instruments are used to nήnimize trauma and reduce the risk of serious injury to the patient. Typically, these instruments consist of an outer hollow needle, referred to as a "cutting cannula," and a coaxial inner needle, referred to as a "stylet." The stylet has a notch proximate the end thereof so that when the stylet is advanced into the targeted tissue of interest, a tissue sample is received in the notch.
The stylet and cannula usually are contained within, and extend from, one end of a housing. In order to obtain a tissue specimen, the entire instrument is moved forward and the needles are advanced through the tissue. Once the desired location is reached, the stylet is advanced into the adjacent tissue of interest, followed by the cutting cannula. As the cutting cannula advances forward
over the stylet, prolapsed tissue is severed and trapped within the notch of the stylet. The instrument is then withdrawn and the tissue sample removed from the notch for analysis.
One example of a biopsy instrument is disclosed in U.S. Patent No. 4,699,154 to Lindgren. The Lindgren patent is understood to disclose a biopsy needle instrument that automatically projects the cannula immediately after the stylet is fired. However, this arrangement is disadvantageous in that it does not allow the physician to first determine whether the stylet has been deployed into the targeted tissue of interest (e.g., a tumor) before the cutting cannula is fired.
U.S. Patent No. 4,958,625 to Bates et al. is understood to disclose a biopsy needle instrument that, in part, attempts to address the problem of the device disclosed in the Lindgren patent by providing a locking-mechanism in one embodiment for preventing automatic deployment of the cannula upon deployment of the stylet. Thus, if it is determined that the stylet missed the targeted area, unnecessary damage to healthy tissue by projection of the cannula can be avoided. To activate the cannula, the locking-mechanism is moved to an unlocked position and pressure is applied to a slide switch. The Bates device suffers from the disadvantage that the switch for firing the cannula is separate from the button used to fire the stylet. Thus, pressure must be applied at separate locations on the device for firing the stylet and the cannula, which may make the device difficult to operate. Thus, a need exists for new and improved tissue-sampling instruments, and methods for their use.
SUMMARY
The present invention provides a tissue-sampling device having an inner stylet, an outer cannula, and a single trigger-mechanism that can be used to independently activate both the stylet and the cannula. For example, in particular embodiments, when the stylet and cannula are in retracted positions, depressing the trigger-mechanism a first time causes the stylet, but not the cannula, to advance to an extended position. Depressing the trigger-mechanism a second time causes the cannula to advance to an extended position over the stylet. In alternative embodiments, the trigger mechanism can be used to incrementally advance the cannula to a series of extended positions over the stylet.
More specifically, a tissue-sampling device according to one representative embodiment includes a housing having a first opening. A needle assembly includes a hollow cannula extending outwardly through the first opening so that a distal end of the cannula is positioned outside the housing. A stylet of the needle assembly is at least partially received in the cannula and has a distal end with at least one tissue-receiving recess, or notch. A first biasing-mechanism is configured to urge the cannula distally in a first direction from a retracted position to an extended position. A second biasing-mechanism is similarly configured to urge the stylet distally in the first direction from a retracted position to an extended position. First and second latch-mechanisms are configured to releasably hold the stylet and the cannula, respectively, in their retracted positions. A firing-mechanism is provided for actuating both the stylet and cannula. The firing- mechanism is configured to be positionable at a plurality of positions for independently deploying the cannula and stylet to their extended positions. More specifically, when the firing-mechanism is moved from a first position to a second position, the firing-mechanism causes the first latch- mechanism to release the stylet and thus allow the stylet to move to its extended position under the biasing force of the second biasing-mechanism. In its fully extended position, the distal end of the stylet extends beyond the distal end of the cannula at least enough to advance the tissue-receiving recess into the tissue of interest. When the firing-mechanism is moved from the second position to a third position, the firing-mechanism causes the second latch-mechanism to release the cannula and thus allow the cannula to move to its extended position over the stylet under the biasing force of the first biasing-mechanism. As the cannula is driven over the stylet, tissue in the tissue-receiving recess is sheared off from any surrounding tissue by the distal end of the cannula.
Since a single firing-mechanism is configured to deploy both the stylet and the cannula, the instrument may be operated to retrieve a tissue sample while maintaining hand position on the instrument. This allows a user (e.g., a physician) to operate the instrument with only one hand. Unlike conventional biopsy instruments, the user is not required to adjust the settings of a selector switch or apply pressure at multiple locations on the instrument to deploy the stylet and cannula. In addition, because the firing-mechanism provides for independent firing of the stylet and cannula, the user is given the opportunity to withdraw the stylet from the patient and/or re-position the instrument before activating the cannula.
The instrument may also include a cocking-mechanism configured to retract the cannula and the stylet from their extended positions to their retracted positions after the cannula and the stylet have been deployed to retrieve a tissue sample. In a specific implementation, the cocking-mechanism is supported for movement relative to the housing. Movement of the cocking-mechanism over a first. distance causes the cannula to move back to its retracted position to allow the second latch- mechanism to re-latch the cannula. Further movement of the cocking-mechanism over a second distance beyond the first distance causes the stylet to move back to its retracted position to allow the first latch-mechanism to re-latch the cannula.
The instrument desirably has a locking-mechanism, or safety-switch, to prevent inadvertent firing of the cannula. The locking-mechanism is adapted for movement between a locked position and a release position. When the locking-mechanism is in the locked position, the locking- mechanism is in position to oppose the release of the second latch-mechanism. When the locking- mechanism is in the release position, the locking-mechanism is removed from opposing the release of the second latch-mechanism. A tissue-sampling device according to another representative embodiment comprises a housing defining an opening. An outer cannula is supported in the housing and extends outwardly through the opening. The cannula is movable between a retracted position and an extended position. An inner stylet is slidably received in the cannula and is also movable between a retracted position and an extended position. An activation-element, such as a trigger-mechanism in disclosed embodiments, is provided for independently deploying the stylet and the cannula to their respective extended positions. The activation-element is configured such that, when the stylet and the cannula are in their respective retracted positions, activating the activation-element (e.g., by depressing the activation-element) a first time causes the stylet but not the cannula to deploy to its extended position, and activating the activation-element a second time causes the cannula to deploy to its extended position.
A tissue-sampling device according to yet another representative embodiment comprises a housing defining an opening. A cannula is supported in the housing and extends outwardly through the opening. The cannula is movable between a retracted position, a first extended position and a second extended position. A stylet is slidably received in the cannula and is movable between a
retracted position and an extended position. A trigger-mechanism is operatively coupled to the cannula. The trigger-mechanism is configured such that, when the stylet is in its extended position and the cannula is in its retracted position, activating the trigger-mechanism causes the cannula to deploy to its first extended position and activating the trigger-mechanism another time causes the cannula to deploy from its first extended position to its second extended position.
In a disclosed embodiment, the trigger-mechanism is operatively coupled to both the stylet and the cannula. Thus, the trigger-mechanism in this embodiment is configured such that, when the stylet and cannula are in their respective retracted positions, activation of the trigger-mechanism a first time causes the stylet to deploy to its extended position, activation of the trigger-mechanism a second time causes the cannula to deploy to its first extended position and activation of the trigger- mechanism a third time causes the cannula to deploy from its first extended position to its second extended position.
A tissue-sampling device according to still another representative embodiment comprises a cannula and a stylet slidably received in the cannula and formed with at least first and second longitudinally spaced tissue-receiving notches. The stylet and cannula are operable to move longitudinally with respect to each other. A trigger-mechanism is operatively coupled to the cannula. The trigger-mechanism is configured such that, whenever the stylet is in an extended position and the cannula is in a retracted position, activating the trigger-mechanism causes the cannula to move to an extended position over the first tissue-receiving notch but not the second tissue-receiving notch, and activating the trigger-mechanism another time causes the cannula to move to an extended position over the second tissue-receiving notch.
The foregoing and other features and advantages of the invention will become more apparent from the following detailed description of several embodiments, which proceeds with reference to the accompanying figures.
BRIEF DESCRIPTION OF THE DRA WINGS
FIG. 1 is a side elevation view of a biopsy instrument according to one embodiment.
FIG. 1A is a top plan view of the biopsy instrument shown in FIG. 1.
FIG. 2A is a front elevation view of the biopsy instrument taken along line 2-2 of FIG. 1.
FIG. 2B is a back elevation view of the biopsy instrument of FIG. 1.
FIG. 3 is a vertical section of the biopsy instrument taken along lines 3-3 of FIGS. 1A and
2A.
FIG. 4 is a vertical section of the biopsy instrument taken along lines 4-4 of FIGS. 1A and
2B.
FIG. 5 is a horizontal section of the biopsy instrument taken along line 5-5 of FIG. 1.
FIG. 6 is a horizontal section of the biopsy instrument taken along line 6-6 of FIG. 1.
FIG. 7 is a horizontal section of the biopsy instrument taken along line 7-7 of FIG. 1.
FIG. 8 is a horizontal section of the biopsy instrument taken along line 8-8 of FIG. 1. FIGS. 9 and 9A show a side elevation view and a top plan view, respectively, of a biopsy instrument according to another embodiment.
FIG. 10 is a front elevation view of the biopsy instrument of FIGS. 9 and 9A taken along line 10-10 of FIG. 9.
FIG. 11A is a vertical section of the biopsy instrument of FIGS. 9 and 9A taken along lines 11-11 of FIGS. 9 A and 10 showing the cannula-assembly and the stylet-assembly in their respective retracted positions.
FIG. 1 IB is a view similar to FIG. 11 A showing the stylet-assembly in its extended position and the cannula-assembly in its retracted position.
FIG. 1 IC is a view similar to FIG. 11A showing the stylet-assembly in its extended position and the cannula-assembly in its first extended position with the distal end of the cannula extending past a first set of tissue-receiving notches in the stylet.
FIG. 1 ID is a view similar to FIG. 11A showing the stylet-assembly in its extended position and the cannula-assembly in its second extended position with the distal end of the cannula extending past a second set of tissue-receiving notches in the stylet. FIG. 1 IE is a view similar to FIG. 11A showing the stylet-assembly in its extended position and the cannula-assembly in its third extended position with the distal end of the cannula extending past a third set of tissue-receiving notches in the stylet.
FIG. 12 is a vertical section of the biopsy instrument of FIGS. 9 and 9A taken along lines 12-12 of FIGS. 9A and 10.
FIG. 13 is a horizontal section of the biopsy instrument of FIGS. 9 and 9A taken along line 13-13 of FIG. 9.
FIG. 14 is a horizontal section of the biopsy instrument of FIGS. 9 and 9A taken along line 14-14 of FIG. 9. FIG. 15 is a horizontal section of the biopsy instrument of FIGS. 9 and 9A taken along line
15-15 of FIG. 9.
FIG. 16 is an enlarged, cross-sectional view of the distal end portions of the cannula and stylet of the biopsy instrument of FIGS. 9 and 9A.
DETAILED DESCRIPTION
According to one aspect, a tissue-sampling instrument or biopsy instrument is configured to permit a user, such as a physician or other health care professional, to independently actuate a stylet- assembly and a cannula-assembly of a needle system to obtain a tissue sample using a single activation-element (also referred to herein as a trigger-mechanism or firing-mechanism). Thus, when activated (e.g., by depressing a button), the activation-element deploys the stylet-assembly, but not the cannula-assembly. After the stylet-assembly is deployed, the cannula-assembly may be deployed upon further activation of the activation-element. In one embodiment, for example, movement of the activation-element from a first position to a second position causes a stylet of the stylet-assembly to advance into the targeted tissue. Further movement of the activation-element from the second position to a third position causes a cutting cannula of the cannula-assembly to advance over the specimen notches of the stylet to shear off the tissue in the notches from any surrounding tissue. The instrument can then be removed from the patient for testing of the tissue sample.
More specifically, and referring initially to FIGS. 1 and 1 A, there is shown side and top views respectively, of a biopsy instrument 100 according to one embodiment. Instrument 100 has an elongated housing, or body, 102, which has a top wall 111 , a bottom wall 113, side walls 115 and
117, a front wall 104, and a rear wall 108. A longitudinal axis L extends between the front wall 104 and the rear wall 108. The housing 102 in the illustrated form has a rectangular box-like shape. The particular shape of the housing 102, however, is not limited to that of the illustrated embodiment. Accordingly, the housing 102 may comprise various other geometric shapes. In addition, the housing
502 may include a gun-like handle, configured to allow a user to grip the instrument like a gun, as is generally known in the art.
Referring to FIGS. 3, 6 and 7, a cannula-assembly 119 and a stylet-assembly 305 are supported in the housing 102. Both the cannula-assembly 119 and the stylet-assembly 305 are moveable fore and aft along the longitudinal axis L (as represented by arrows A and B, respectively) relative to each other and the housing 102. When the cannula-assembly 119 and the stylet-assembly 305 are activated to retrieve a tissue sample, they are caused to move forwardly in the A direction from a retracted position, such as shown in FIG. 3, to an extended position. After firing, the cannula- assembly 119 and the stylet-assembly 305 maybe moved rearwardly in the direction of arrow B from their extended positions to their retracted positions for reloading. The operation of the cannula- assembly 119 and the stylet-assembly 305 is described in greater detail below.
The cannula-assembly 119 includes a hollow, elongate cannula 304 that extends outwardly through an opening 302 defined in the front end wall 104 of the housing 102. The cannula 304 has a tapered or beveled distal end 309, as generally known in the art. The proximal end of the cannula 304 (i.e., the end opposite the distal end 309) is connected to a stepped collar 328, the rear portion of which forms a large-diameter collar 330.
A cannula-moving-mechanism, such as a biasing-mechanism or other resilient member, is provided to urge the cannula-assembly 119 to its extended position. In the illustrated embodiment, for example, a compression spring 334 is concentrically disposed around a spring guide 332. The spring guide 332 is connected to and desirably extends from the rear end of collar 330 through an opening in a support member 324, which extends perpendicularly from the side wall 115 of the housing 102 (as best shown in FIG. 7). In an alternative embodiment, the spring guide 332 extends from the rear end of the collar 330 toward the support member 324, but does not extend through the support member 324. In either case, one end of the spring 334 abuts against the rear end of the collar 330 and the other end of spring 334 abuts against the support member 324. In this manner, the biasing force of the compression spring 334 provides the motive force to drive the cannula 304 forwardly to its extended position when activated. The support member 324 maintains the axial alignment of the cannula-assembly 119 and serves as a bearing surface for the spring guide 332 as the cannula-assembly 119 is moved fore and aft.
The stylet-assembly 305 has an elongate stylet 306 that is slidably received in the cannula 304 and corresponding axial bores extending through the collar 328 and the spring guide 334. Like the cannula 304, the stylet 305 also has a tapered or beveled distal end 311. When the stylet 305 is in its retracted, or cocked, position (such as shown in FIG. 3), the distal end 311 desirably is aligned with the distal end 309 of the cannula 304. When activated, the stylet 305 and the cannula 306 desirably move outwardly from the housing 102 an equal distance so that the distal ends 309, 311 of the cannula and stylet 304, 306, respectively, align with each other in their extended positions.
The stylet 306 has at least one tissue-receiving notch or recess for receiving a tissue sample when the stylet 306 is advanced into the tissue of interest. As shown in FIG. 3, for example, elongated notches, or recesses, 308 and 310 are formed in the distal end portion of the stylet 306.
The notches 308, 310 extend longitudinally along the top and bottom, respectively, of the distal end portion of the stylet 306. Although the stylet 306 in the illustrated embodiment is shown as having two tissue-receiving notches, more or fewer notches may be used. Moreover, forms other than the illustrated elongated notches may be used. For example, in alternative embodiments, a tissue- receiving notch may comprise an annular groove.
The proximal end of stylet 306 is connected to a collar 350 (FIGS. 3, 6 and 7). A stylet- moving-mechanism, such as compression spring 354, provides the motive force for moving the stylet-assembly 305 to its extended position. The illustrated compression spring 354 is concentrically disposed around a spring guide 352. The spring guide 352 is connected to the rear surface of the collar 350. Desirably, but not necessarily, the spring guide 352 extends through an opening in a support member 326, which extends perpendicularly from the side wall 115 of the housing 102. Alternatively, the spring guide 352 may extend to a position in front of the support member 326. In either configuration, one end of the spring 354 abuts against the rear surface of the collar 350 and the other end abuts against the support member 326. Thus, the biasing force of the spring 354 urges the stylet 306 forwardly to its extended position. The support member 326 maintains the axial alignment of the stylet-assembly 305 and serves as a bearing surface for the spring guide 352 as the stylet- assembly 305 is move fore and aft.
The cannula-assembly 119 and the stylet-assembly 305 desirably are retained in their retracted positions by respective latch-mechanisms. Referring to FIGS. 3, 4 and 5, a cannula-latch-
mechanism 336 comprises a rocker-arm 337 pivotally mounted on a pivot pin 116, which is connected at each end to a respective side wall 115, 117 (as best shown in FIG. 5). As best shown in FIG. 3, the rocker-arm 337 has a distal end 338 configured to engage the collar 330. The cannula- latch-mechanism 336 also has a downwardly extending trigger-engaging portion 404 (as best shown in FIG. 4). The trigger-engaging portion 404 has an angled lower surface 407 that is adapted to engage a corresponding inclined trigger-surface 411 of a trigger-mechanism 120 (described below). The rocker-arm 337 is pivotable about pin 116, in the directions indicated by arrows E and F, between a latched position (such as shown in FIG. 3) and an unlatched position. In the latched position, a vertical surface 136 of the distal end 338 engages the vertical leading edge 138 of the collar 330 (as best shown in FIG. 6) to retain the cannula-assembly 119 in its retracted position against the biasing force of the compression spring 334. To unlatch the cannula-assembly 119 from the cannula-latch-mechanism 336, the trigger-mechanism 120 is moved in the A direction to cause the trigger-surface 411 to bear against the lower surface 407 of the trigger-engaging portion 404, which in turn causes upward pivoting of the rocker-arm 337 in the F direction. When the rocker-arm 337 has pivoted to the point at which the distal end 338 releases the collar 330, the cannula-assembly 119 is deployed to an extended position under the biasing force of the compression spring 334.
An optional biasing-mechanism may be provided to urge the cannula-latch-mechanism 336 to its latched position of FIG. 3. For example, in the illustrated embodiment, a leaf spring 130 is interposed between the top surface of the rocker-arm 337 and the inner surface of the top wall 111 (FIG. 3). The biasing force of the leaf spring 130 causes the rocker-arm 337 to pivot downwardly, in the direction of arrow E, for engagement with the collar 330 when the cannula-assembly 119 is moved back to its retracted position. If a biasing-mechanism, such as the leaf spring 130, is not provided, the proximal end of the compression spring 334 may be situated to at least partially contact a lower portion 339 of the rocker-arm 337 below pin 116. In this configuration, when the cannula- assembly 119 is moved back to its retracted position, compression of the spring 334 against portion 339 of the rocker-arm 337 causes the distal end 338 to pivot downwardly, in the direction of arrow E, for engagement with the collar 330.
A motion-limiting member (not shown) may be disposed within the housing 102 to prevent the rocker-arm 337 from rotating under the biasing force of the leaf spring 130 in the E direction past
- l i ¬
the substantially horizontal position shown in FIG. 3 after the cannula-assembly 119 is deployed to its extended position. A motion-limiting member may comprise, for example, a projection extending inwardly from one of the side walls 115, 117 underneath the lower surface of the rocker-arm 337. A stylet-latch-mechanism 340, the construction of which is identical to the cannula-latch- mechanism 336, is provided for retaining the stylet-assembly 305 in its retracted position. The stylet- latch-mechanism 340 comprises a rocker-arm 341 pivotably disposed on a pivot pin 118 that is connected at each end to a respective side wall 115, 117 (as best shown in FIG. 5). As best shown in FIG. 3, the rocker-arm 341 has a distal end 342 configured to engage the collar 350. The stylet-latch- mechanism 340 also has a downwardly extending trigger-engaging portion 406 (as best shown in FIG. 4). The trigger-engaging portion 406 has an angled lower surface 403 that is adapted to engage a corresponding inclined trigger-surface 412 of the trigger-mechanism 120.
The rocker-arm 341 is pivotable about pin 118, in the directions indicated by arrows E and F, between a latched position (such as shown in FIG. 3) and an unlatched position. In the latched position, a vertical surface 140 of the distal end 342 engages the vertical leading edge 142 of the collar 350 (as best shown in FIG. 6) to retain the stylet-assembly 305 in its retracted position against the biasing force of the compression spring 354. To unlatch the stylet-assembly 305 from the stylet- latch-mechanism 340, the trigger-mechanism 120 is moved in the A direction to cause the trigger- surface 412 to bear against the lower surface 403 of the trigger-engaging portion 406, which in turn' causes upward pivoting of the rocker-arm 341 in the F direction. When the rocker-arm 341 has pivoted to the point at which the distal end 342 releases the collar 350, the stylet-assembly 305 is deployed to an extended position under the biasing force of the compression spring 354.
An optional leaf spring 132 may be interposed between the top surface of the rocker-arm 341 and the inner surface of the top wall 111 for urging the rocker-arm 341 downwardly for engagement with collar 350 when the stylet-assembly 305 is moved back to its retracted position. In addition, a motion-limiting member (not shown) may be disposed within the housing 102 to prevent the rocker-arm 341 fromrotating under the biasing force of the leaf spring 132 in the E direction past the substantially horizontal position (shown in FIG. 3) after the stylet-assembly 305 is deployed to its extended position. If leaf spring 132 is not provided, the compression spring 354 may be situated with its proximal end in contact with a lower portion 343 of the rocker-arm 341 below pin 118 to
urge the distal end 342 downwardly for engagement with collar 350 when the stylet-assembly 305 is moved back to its retracted position.
Referring to FIGS. 4, 5 and 6, the trigger-mechanism 120 in the illustrated form includes an elongated trigger-shaft 124. The trigger-shaft 124 extends outwardly through an opening 402 defined in the back end wall 108 of the housing 102 (FIG. 4). The proximal end of the trigger-shaft 124 forms a user-engageable button 122. The trigger-shaft 124 is supported within the housing 102 on a recessed portion 420b of a trigger pad 420 (as best shown in FIG. 4). The trigger-mechanism 120 is slidable longitudinally fore and aft relative to the trigger pad 420. A vertical ledge 422 extending between the upper surface of the recessed portion 420b and the upper surface of a distal end portion 420a of the trigger pad 420 limits the forward movement of the trigger-mechanism 120.
The distal end portion of the trigger-shaft 124 defines the inclined trigger-surface 411 for engaging the lower surface 407 of the trigger-engaging portion 404 of the cannula-latch-mechanism 336. The trigger-shaft 124 also has a recessed portion 413 disposed in the housing 102. The proximal end portion of the recessed portion 413 defines the inclined trigger-surface 412 for engaging the lower surface 403 of the trigger-engaging portion 406 of the stylet-latch-mechanism 340.
A stop-member 416 extends inwardly from the side wall 117 over the recessed area 413 of the trigger-shaft 124. As can be seen in FIG. 4, the stop member 416 is positioned to engage a vertical ledge 414 at the distal end of the recessed portion 413 and therefore limit backward movement of the trigger-shaft 124. A trigger-guide 418 also extends inwardly from the side wall 117 over the recessed portion 413 of trigger-shaft 124. The trigger-guide 418 and the stop-member 416 prevent upward displacement of the trigger-shaft 124 (arrow C in FIG. 4) and provide bearing surfaces for the trigger-mechanism 120, as the trigger-mechanism 120 is moved fore and aft.
Referring to FIGS. 3 and 4, the trigger-surfaces 411, 412 are spaced on the trigger-shaft 124 such that, when the trigger-mechanism 120 is moved forwardly over a first distance, the trigger- surface 412 engages the corresponding lower surface 403 of the trigger-engaging portion 406 of the stylet-latch-mechanism 340, which in turn causes the rocker-arm 341 to pivot upward and release the stylet-assembly 305. As the trigger-mechanism 120 is moved through the first distance to deploy the stylet-assembly 305, the trigger-surface 411 remains spaced from the corresponding lower surface 407 of the trigger-engaging portion 404 of the cannula-latch-mechanism 336. Consequently, the
cannula-assembly 119 remains latched in its retracted position by the cannula-latch-mechanism 336. Upon further forward movement of the trigger-mechanism 120 over a second distance beyond the first distance, the trigger-surface 411 engages the lower surface 407, which causes the rocker arm 337 to pivot upward and release the cannula-assembly 119. An optional safety-switch, or locking-mechanism, 109 may be provided to prevent inadvertent firing of the cannula-assembly 119. The safety-switch 109, as best shown in FIG. 3, includes a horizontal slide member 126 and user-engageable tab, or button, 114. The tab 114 extends through an opening 202 defined in the top wall 111 of the housing 102. The safety-switch 109 is operable to slide fore and aft between a locked position (as shown in FIG. 3) and an unlocked position (not shown). In the locked position, the slide member 126 is disposed between the top surface of the rocker-arm 337 and the inner surface of the top wall 111 to oppose upward pivoting of the rocker-arm 337, and thereby prevent deployment of the cannula-assembly 119. To unlock the cannula-latch-mechanism 336, the safety-switch 109 is slid forwardly in the A direction until the slide member 126 is no longer in a position over the rocker-arm 337 to oppose its upward pivoting movement.
Referring to FIGS. 3, 5, 6 and 8, a cocking-mechanism 315 may be provided to return the cannula-assembly 119 and the stylet-assembly 305 back to their retracted positions after being deployed. The cocking-mechanism 315 is mounted for fore and aft movement along the inner surface of the bottom wall 113. As best shown in FIG. 3, the cocking-mechanism 315 has a longitudinally extending body 316 and a vertically upright front-end member 317 positioned in front of the collar 328. The front-end member 317 defines an opening 134 through which the cannula 304 and stylet 306 extend (FIGS. 5, 6 and 7). The opening 134 is dimensioned to permit fore and aft longitudinal movement of the cannula 304 but restrict the forward movement of the collar 328 into or through the opening 134. The base 316 also has a vertically upright rear-end member 318 and a vertically upright member 320 positioned in front of the collar 350 (as best shown in FIG. 3). As best shown in FIG. 8, a post, or projection, 322 extends perpendicularly from one side of the base 316 at a position in front of the distal end 410 of the trigger-shaft 124.
A user-engageable switch, or knob, 112 extends perpendicularly from one side of the front- end member 317 through a longitudinal slot or opening 110 defined in the side wall 115 (FIGS. 1 and
7). The knob 112 is moveable longitudinally fore and aft in the slot 110 to cause fore and aft longitudinal movement of the cocking-mechanism 315 inside the housing 102. As can be seen in FIG. 1, fore and aft movement of the cocking knob 112 is limited by the ends of the slot 110. The cocking knob 112 extends through the slot 110 a sufficient amount to permit manipulation of the knob 112 with a thumb or finger.
When the cannula-assembly 119 is deployed, the collar 328 bears against the front-end member 317 and therefore moves the cocking-mechanism 315 to a forward position (not shown). When the knob 112 is retracted (i.e., moved in a rearward direction), front-end member 317 bears against the collar 328 to cause rearward movement of the cannula-assembly 119. Similarly, member 320 bears against the collar 350 to cause rearward movement of the stylet-assembly 305, and post 322 bears against the distal end 410 of the trigger-shaft 124 to cause rearward movement of the trigger-mechanism 120. The operation of the cocking-mechanism 315 is described in greater detail below.
Referring to FIGS. 1-8, the operation of instrument 100 will now be described. Instrument 100 is shown in a cocked or ready-to-fire position in FIGS. 1-8. In this position, the trigger- mechanism 120 is moved to its farthest extent in the B direction (as best shown in FIG. 4) and the cannula-latch-mechanism 336 and the stylet-latch-mechanism 340 are in their latched positions for releasably holding the cannula-assembly 119 and the stylet-assembly 305, respectively (as best shown in FIG. 3) in their retracted positions. As mentioned, the distal end 311 of the stylet 306 desirably is aligned with the distal end 309 of the cannula 304 when the stylet 306 and cannula 304 are in their retracted positions.
To obtain a tissue sample for the purpose of, among other things, testing such tissue, the distal ends 309, 311 of the cannula and the stylet 304, 306, respectively, are positioned adjacent to, or within, the tissue of interest in a conventional manner. Once the instrument 100 is properly positioned, the button 122 of the trigger-mechanism 120 is depressed a distance sufficient to cause the trigger-surface 412 to engage the trigger-engaging portion 406 and cause the rocker-arm 341 to pivot upward and relase the stylet-assembly 305. This allows the stylet-assembly 305 to move to its extended position under the biasing force of the compression spring 354, thereby causing the stylet 306 to advance forwardly into the adjacent tissue. In its extended position, the distal end 311 of the
stylet 306 desirably extends past the distal end 309 of the cannula 304 at least enough to fully expose the specimen notches 308 and 310 to the tissue of interest. The firing of the stylet-assembly 305 also causes the collar 350 to engage the member 320 of the cocking-mechanism 315 and therefore move the cocking-mechanism 315 to a forward position (not shown). At this point, the physician (or other health care professional) operating the instrument 100 may now examine the tissue into which the stylet 306 has been deployed to determine whether the stylet 306 has been properly deployed into the tissue of interest. If the stylet 306 missed the targeted tissue and is instead embedded in adjacent healthy tissue, the stylet 306 may be removed without further damage to the healthy tissue. If, on the other hand, the stylet 306 has been properly deployed into the targeted tissue, the safety-switch 109 can be moved to its unlocked position to permit firing of the cannula-assembly 119.
To fire the cannula-assembly 119, the button 122 of the trigger-mechanism 120 is further depressed a distance sufficient to cause the trigger-surface 411 to engage the trigger-engaging portion 404 and cause the rocker-arm 337 to pivot upward and relase the cannula-assembly 119. This allows the cannula-assembly 119 to move to its extended position under the biasing force of the compression spring 334, thereby causing the cannula 304 to advance forwardly over the stylet 306. As the cannula 304 is driven over the stylet 306, the tissue in notches 308, 310 is sheared off from any surrounding tissue by the cannula 304. When the cannula 304 is deployed to its extended position, the distal end 309 of the cannula 304 is again aligned with the distal end 311 of the stylet 306. After firing the cannula-assembly 119, the instrument 100 may be removed from the patient and the tissue samples removed from the notches 308, 310. To remove the tissue sample from the notches 308, 310, the cannula-assembly 119 is retracted (i.e., returned to its retracted position) to expose the tissue samples in the notches 308, 310. To retract the cannula-assembly 119, knob 112 of the cocking-mechanism 315 is retracted (i.e., moved in the rearward direction) a distance sufficient to cause the collar 330 to slide back under the distal end 338 of the rocker-arm 337. When the leading edge 138 of the collar 330 is at a position behind the vertical surface 136 of the distal end portion 338, the biasing force of the leaf spring 130 returns the rocker-arm 337 to its latched position for retaining the cannula-assembly 119 against the biasing force of compression spring 334.
As mentioned, retraction of the knob 112 also causes post 322 of cocking-mechanism 315 to bear against the distal end 410 of the trigger-shaft 124, thereby moving the trigger-mechanism 120 back toward its pre-firing position. In addition, member 320 of the cocking-mechanism 315 bears against collar 350 to move the stylet-assembly 305 toward its retracted position. However, without further retraction of the knob 112 beyond the position where cannula-latch-mechanism 336 latches onto the collar 330, the collar 350 will remain spaced, and therefore unlatched from the respective rocker-arm 341 of the stylet-latch-mechanism 340. Thus, once the cannula-assembly 119 is retained in its retracted position, knob 112 can be released to allow the stylet 306 to move to its extended position under the biasing force of the compression spring 354 to expose the tissue samples, at which point the tissue samples can be removed for analysis and/or storage. To prevent inadvertent firing of the cannula-assembly 119, the safety-switch 109 can be returned to its locked position (FIG. 3)
Following removal of the tissue samples, the exposed distal end portion of the stylet 306, including the notches 308, 310, may be cleaned in a convention manner. Thereafter, the stylet- assembly 305 can be returned to its retracted position by retracting knob 112 until the leading edge 142 of the collar 350 is at a position behind the vertical surface 140 of the distal end 342 of the rocker-arm 341 to allow the leaf spring 132 to return the rocker-arm 341 to its latched position for retaining the stylet-assembly 305.
Before the instrument 100 is reused, it may be sterilized in a conventional manner. In an alternative embodiment, a biopsy instrument is adapted to receive a removable, disposable needle system. In this configuration, a needle system may be removed and replaced with a new needle system after each use.
Referring now to FIGS. 9-16, there is shown a biopsy instrument 500 according to another embodiment for retrieving tissue" samples. As best shown in FIGS. 9, 9A and 10, instrument 500, like instrument 100 of FIGS. 1-8, comprises an elongated housing 502 having a generally rectangular box-like shape with a top wall 504, a bottom wall 506, a front wall 508, a rear wall 510, and opposing side walls 512 and 514. A longitudinal axis L of the housing 502 extends between the front wall 508 and the rear wall 510. Configurations for the housing 502 other than the illustrated rectangular boxlike shape also may be used. In addition, the housing 502 may include a gun-like handle, as is generally known in the art.
As best shown in FIGS. 11A and 14, a cannula-assembly 516 and a stylet-assembly 518 are supported in the housing 502. Both the cannula-assembly 516 and the stylet-assembly 518 are moveable fore and aft along the longitudinal axis L, as indicated by arrows A and B in FIG. 11 A, respectively, relative to each other and the housing 502. The cannula-assembly 516 comprises an elongate cannula 522 coupled to a stepped collar 520, the rear portion of which forms a larger- diameter collar 520a that serves as a latch member for the cannula-assembly 516. The cannula 522 extends outwardly through an opening 524 defined in the front wall 508 of the housing 502. The cannula 522 may have a tapered or beveled distal end 530, as generally known in the art. A compression spring 526 is concentrically disposed around a spring guide 528. The spring guide 528 is coupled to and extends rearwardly from the collar 520a through an opening in a support member 532, which extends inwardly from the side wall 512. One end of the spring 526 abuts against the collar 520a and the other end of the spring 526 abuts against the support member 532 and a projection 636 that depends from the lower surface of the rocker-arm 570 below pin 572. The biasing force of the spring 526 provides the motive force to drive the cannula 522 in the forward direction, as represented by arrow A, when the cannula 522 is activated.
The stylet-assembly 518 comprises an elongate stylet 534 that is slidably received in the cannula 522 and corresponding axial bores extending through the stepped collar 520 and the spring guide 528. As best shown in FIG. 16, the stylet 534 has a distal end 536 that may be tapered or beveled to correspond to the tapered distal end 530 of the cannula 522. When the stylet 534 is in its retracted, or cocked, position (such as shown in FIG. 11 A), the distal end 536 of the stylet 534 desirably is aligned with the distal end 530 of the cannula 522 (as best shown in FIG. 16).
Referring to FIGS. 11A and 14, the proximal end of the stylet 534 is connected to a collar 540 that serves as a latch member for the stylet-assembly 518. A compression spring 542 is concentrically disposed around a spring guide 544. The spring guide 544 is coupled to and extends rearwardly from the collar 540 through an opening in a support member 546, which extends inwardly from the side wall 512 of the housing 502. One end of the spring 542 abuts against the collar 540 and the other end of the spring 542 abuts against the support member 546 and a projection 638 that depends from the lower surface of the rocker-arm 550 below pin 552. The biasing force of the spring
542 provides the motive force to drive the stylet 534 in the forward direction, as represented by arrow A, when the stylet 534 is activated.
Referring to FIG. 16, a plurality of tissue-receiving notches 538a, 538b, 538c, 538d, 538e and 538f are formed in the distal end portion of the stylet 534. Notches 538a, 538b and 538c are longitudinally spaced along the top of the stylet 534 and are aligned with notches 538d, 538e and
538f, respectively, longitudinally spaced along the bottom of the stylet 534. Notches 538c and 538f comprise a first set of notches; notches 538b and 538e comprise a second set of notches; and 538a and 538d comprise a third set of notches. The notches may have different lengths for obtaining different size tissue samples. In the illustrated embodiment, for example, notches 538c and 538f have a length Li; notches 538b and 538e have a length L2; and notches 538a and 538d have a length L3. Length Li is greater than length L2, which is greater than length L3. Other notch configurations also may be used. For example, more or fewer than the illustrated three sets of notches may be used and/or more or fewer than two notches may be provided in each set of notches.
An activation-element, such as the illustrated trigger-mechanism 558 is provided for activating, or deploying, the stylet-assembly 518 and the cannula-assembly 516. Referring to FIGS. 11-15, the trigger-mechanism 558 comprises an elongate body 560 that extends longitudinally of the housing 502 and through an opening 525 defined in the rear wall 510. The proximal end of the body 560 forms a user-engageable button 562. The body 560 of the trigger-mechanism 558 is supported for longitudinal movement on a trigger pad 563. As best shown in FIG. 12, the body 560 is formed with longitudinally spaced recesses 564a, 564b and 564c and a series of longitudinally spaced trigger- surfaces, namely, a first trigger-surface 566a, a second trigger-surface 566b, a third trigger-surface 566c and a fourth trigger-surface 566d. Laterally extending projections 626 and 628 disposed on the inner surface of side wall 514 are positioned in recess 564a to prevent upward displacement of the trigger-mechanism 558 and provide upper bearing surfaces for the trigger-mechanism 558. The trigger-mechanism 558 is configured such that, as the trigger-mechanism 558 is moved in the forward direction, each trigger-surface 566a, 566b, 566c and 566d successively engages a trigger-engaging . portion of an associated latch-mechanism for deploying the stylet-assembly 518 to an extended position and thereafter deploying the cannula-assembly 516 to a series of extended positions, as described in greater detail below.
Like the embodiment of FIGS. 1-8, and as best shown in FIG. 11 A, the stylet-assembly 518 is releasably retained in its retracted position by a stylet-latch-mechanism 548 which comprises a rocker-arm 550 pivotably disposed on a pivot pin 552. Each end of the pin 552 is connected to a respective side wall 512, 514 of the housing (as best shown in FIG. 13). The rocker-arm 550 is formed with a downwardly extending distal end 554 that is configured to engage a top portion of the collar 540 for retaining the stylet-assembly 518 in its retracted position. As best shown in FIG. 12, the stylet-latch-mechanism 548 includes a downwardly extending trigger-engaging portion 556, the bottom end of which is positioned in the first recess 564a of the trigger-mechanism 558 proximate the first trigger-surface 566a. Referring to FIGS. 11A, 12 and 13, a first cannula-latch-mechanism 568, the construction of which is identical to the stylet-latch-mechanism 548, is provided for releasably holding the cannula- assembly 516 in a retracted position. The first cannula-latch-mechanism 568 comprises a rocker-arm 570 pivotably disposed on a pivot pin 572. The rocker-arm 570 is formed with a downwardly extending distal end 574 that is configured to engage a top portion of the collar 520a for retaining cannula-assembly 516 in its retracted position (FIG. 11 A). The first cannula-latch-mechanism 508 also has a downwardly extending trigger-engaging portion 576, the bottom end of which is positioned in the second recess 564b of the trigger-mechanism 558 (FIG. 12).
A second cannula-latch-mechanism 580 is positioned forward the first cannula-latch- mechanism 568 and a third cannula-latch-mechanism 582 is positioned forward the second cannula- latch-mechanism 580. The second cannula-latch-mechanism 580 has a respective a rocker-arm 584 having a distal end 586 and pivotably mounted on a respective pivot pin 596 (FIG. 11 A) The second cannula-latch-mechanism 580 has a downwardly extending trigger-engaging portion 588 positioned in the third recess 564c of the trigger-mechanism 558 (FIG. 12). Similarly, the third cannula-latch- mechanism 582 has a respective rocker-arm 590 having a distal end 592 and is pivotably mounted on a respective pivot pin 598 (FIG. 11A). The third cannula-latch-mechanism 582 also has a downwardly extending trigger-engaging portion 594, which is positioned forward the fourth trigger- surface 566d of the trigger-mechanism 558 (FIG. 12). Support members (not shown) may be disposed in the housing 502 to support rocker-arms 584 and 590 of the second and third cannula- latch-mechanisms 580, 582, respectively, in their substantially horizontal positions shown in FIG.
11 A. Suitable support members may comprise, for example, projections disposed on one of the side walls 512, 514 and extending underneath the rocker-arms 584, 590 at positions to support the rocker- arms 584, 590 in their substantially horizontal positions.
As best shown in FIG. 11 A, biasing elements, such as leaf springs 630 and 632, may be provided to bias the rocker-arms 584 and 590 of the second and third cannula-latch-mechanisms 580 and 582, respectively, toward their substantially horizontal positions. The illustrated leaf springs 630, 632 are coupled to the inner surface of the top wall 504 and are positioned to bear against rocker- arms 584, 590, respectively.
An optional safety-switch, or locking-mechanism, 618 maybe provided to prevent inadvertent firing of the stylet-assembly 518. The safety-switch 618, as best shown in FIGS. 9A and 11 A, includes a horizontal slide member 620 and switch 622 that extends upwardly through an opening 624 defined in the top wall 504 of the housing 502. The safety-switch 618 is operable to slide fore and aft between a locked position for locking the stylet-latch-mechanism 548 and an unlocked position for unlocking the stylet-latch-mechanism 548. In the locked position, the slide member 620 is disposed between the top surface of the rocker-arm 550 and the inner surface of the top wall 504 (FIG. 11A) to oppose upward pivoting of the rocker-arm 550, and thereby prevent deployment of the stylet-assembly 518. To unlock the stylet-latch-mechanism 548, the safety-switch 618 is slid forwardly until the slide member 620 is no longer in a position over the rocker-arm 550 to oppose its upward pivoting movement (FIG. 1 IB). In alternative embodiments, one or more safety- switches can be similarly provided for one or more of the first, second and third cannula-latch- mechanisms 568, 580 and 582.
Referring to FIGS. 11 A, 14 and 15, a cocking-mechanism 600 is provided to return the cannula-assembly 516 and stylet-assembly 518 to their retracted positions and permit removal of the tissue samples from the notches. The illustrated cocking-mechanism 600 comprises a longitudinally extending body 602 mounted for fore and aft movement along the inner surface of the bottom wall 506. The body 602 includes a vertically upright front-end portion 604 and a vertical projection 612 proximate the rear end of the body 602. The front-end portion 604 defines an opening 606 through which the cannula 522 and stylet 534 extend (as best shown in FIG. 14). A switch, or knob, 608 extends perpendicularly from one side of the front-end portion 604 through a longitudinal slot, or
opening, 610, defined in the side wall 512 of the housing 502 (FIGS. 9 and 14). As best shown in FIG. 15, a generally rectangular-shaped recess 614 is formed on one side of the body 602 for receiving a laterally extending projection 616 of the body 560 of the trigger-mechanism 558.
The illustrated biopsy instrument 500 is configured to allow a user to deploy the stylet 534 without deploying the cannula 522, and thereafter successively deploy the cannula 522 over a series of positions over the stylet 534 for successively capturing tissue samples in the first, second and third sets of notches. Explaining the operation of instrument 500, and referring initially to FIGS. 11A, 12 and 13, the stylet-latch-mechanism 548 and the first cannula-latch-mechanism 568 releasably hold the stylet-assembly 518 and the cannula-assembly 516, respectively, in retracted positions (as best shown in FIGS. 11A and 13). In this state, the biopsy instrument 500 can be positioned by a user for retrieving tissue samples.
To deploy the stylet 534, the safety-switch 618 is moved to the unlocked position and the trigger-mechanism 558 is moved forward relative to the housing 502, such as by depressing the button 562, a distance sufficient to cause the first trigger-surface 566a to engage the trigger-engaging portion 556 and cause upward pivoting of the rocker-arm 550. When the rocker-arm 550 has pivoted to the point at which its distal end 554 releases the collar 540, the stylet-assembly 518 is moved from a retracted position (FIGS. 11A and 13) to an extended position (FIG. 1 IB) under the biasing force of the spring 542. Deployment of the stylet-assembly 518 also causes die collar 540 to bear against the projection 612 of the cocking-mechanism 600, thereby driving the cocking-mechanism 600 to a forward position (FIG. 1 IB). As shown in FIG. 1 IB, in its extended position, the notches 538a, 538b, 538c, 538d, 538e and 538f of the stylet 534 extend beyond the distal end 530 of the cannula 522.
As with the embodiment of FIGS. 1-8, the trigger-mechanism 558 is configured such that after the trigger-mechanism 558 has been depressed to deploy the stylet-assembly 518 in the manner described above, the first cannula-latch-mechanism 568 remains latched to the collar 520a to prevent deployment of the cannula-assembly 516 (as shown in FIG. 1 IB). Again, this provides the health care professional operating the instrument 500 the opportunity to re-position or completely remove the stylet 534 from the subject (e.g., a patient) if the stylet 534 did not deploy into the targeted area.
The cannula-assembly 516 can be successively deployed to first, second and third extended positions for successively capturing tissue samples in the first set of notches (notches 538c and 538f), the second set of notches (notches 538b and 538e) and the third set of notches (notches 538a and 538d), respectively. To obtain tissue samples in notches 538c and 538f, the button 562 is depressed a distance sufficient to cause the second trigger-surface 566b to engage the trigger-engaging portion 576 of the first cannula-latch-mechanism 568 and cause the rocker-arm 570 to pivot upward and release the collar 520a. This allows the cannula 522 to deploy forwardly under the biasing force of the spring 526 for severing the tissue in notches 538c and 538f from any surrounding tissue. The distal end 586 of the second cannula-latch-mechanism 580 is positioned to contact the collar 520a and arrest the forward movement of the cannula-assembly 516 so that the cannula-assembly 516 is releasably held by the second cannula-latch-mechanism 580 in a first extended position (FIG. 1 IC). In this position, the cannula 522 extends over notches 538c and 538f but stops short of notches 538b and 538e.
If desired, the instrument 500 can now be re-positioned prior to activating the trigger- mechanism 558 for capturing tissue samples in the second set of notches (538b and 538e). To obtain tissue samples in notches 538b and 538e, the button 562 is depressed a distance sufficient to cause the third trigger-surface 566c to engage the trigger-engaging portion 588 of the second cannula-latch- mechanism 580 and cause the rocker-arm 584 to pivot upward and release the collar 520a. This allows the cannula 522 to deploy from the first extended position (FIG. 1 IC) to a second extended position (FIG. 1 ID) for severing the tissue in notches 538b and 538e from any surrounding tissue. In this position, the cannula-assembly 516 is releasably held by the third cannula-latch-mechanism 582 with the cannula 522 extending over notches 538b and 538e but stopping short of notches 538a and 538d.
Again, the instrument 500 may be re-positioned, if necessary, prior activating the trigger- mechanism 120 for capturing tissue samples in the third set of notches (notches 538a and 538d). To capture tissue samples in notches 538a and 538d, the button 562 is depressed a distance sufficient to cause the fourth trigger-surface 566d to engage the trigger-engaging portion 594 of the third cannula- latch-mechanism 582 and cause the rocker-arm 590 to pivot upward and release the collar 520a. This allows the cannula 522 to deploy from the second extended position (FIG. 1 ID) to a third extended
position (FIG. 1 IE) for severing the tissue in notches 538a and 538d from any surrounding tissue. The stylet 534 and cannula 522 can then be withdrawn from the patient to retrieve the tissue samples embedded in the notches.
To permit removal of the tissue samples from the notches, the cannula-assembly 516 is returned to its retracted position by retracting the knob 608 of the cocking-mechanism 600 to cause the front-end portion 604 of the cocking-mechanism 600 to bear against the collar 520 and move the cannula-assembly 516, and therefore the cannula 522, rearwardly against the biasing force of the spring 526. The knob 508 is retracted at least until the collar 520a is positioned behind the distal end 574 of the rocker arm 570. Compression of spring 526 against projection 636 causes the rocker-arm 570 to pivot downwardly to engage collar 520a and restrain the cannula-assembly 516 in its retracted position.
Retraction of the cocking-mechanism 600 also causes a surface portion 634 of the recess 614 (FIG. 15) to bear against projection 616 of the trigger-mechanism 558 and projection 612 to bear against the collar 540. Consequently, retraction of the knob 608 causes simultaneous rearward movement of the trigger-mechanism 558, the stylet-assembly 518 and cannula-assembly 516. This, in turn, allows the leaf springs 630, 632 to return their associated rocker-arms 584, 594, respectively, of the second and third cannula-latch-mechanisms 580, 582, respectively, to the substantially horizontal positions shown in FIG. 11 A.
If the knob 608 is not retracted beyond the position at which the rocker-arm 570 latches onto collar 520a to retain the cannula-assembly 516, the collar 540 of the stylet-assembly 518 will remain spaced, and therefore unlatched from the respective rocker-arm 550 of the stylet-latch-mechanism 548. Thus, with the cannula-assembly 516 retained in its retracted position, the knob 608 of the cocking-mechanism 600 can be released to allow the compression spring 542 to move the stylet- assembly 518 to move to its extended position to expose the notches 538a, 538b, 538c, 538d, 538e and 538f (such as shown in FIG 1 IB) and allow the tissue samples to be removed. Following removal of the tissue samples, the stylet 534 may be cleaned and/or returned to its retracted position by retracting the knob 608 until the rocker-arm 550 of the stylet-latch-mechanism 548 latches onto the collar 540.
The present invention has been shown in the described embodiments for illustrative purposes only. The present invention may be subject to many modifications and changes without departing from the spirit or essential characteristics thereof. We therefore claim as our invention all such modifications as come within the spirit and scope of the following claims.