Abstract:
The present invention provides automated biopsy instruments especially useful for improving minimally invasive medical procedures to obtain soft tissue biopsy samples. The biopsy instruments provide side-by-side actuators which retract a stylet and a cannula in specific sequences. The biopsy instruments may include a single spring or two springs to sequentially fire the stylet and the cannula.

Description:
RELATED APPLICATION DATA 
     This application is a divisional of parent U.S. patent application Ser. No. 08/474,756 filed Jun. 7, 1995, now U.S. Pat. No. 5,779,647 which issued on Jul. 14, 1998. 
    
    
     FIELD OF THE INVENTION 
     This invention generally relates to biopsy instruments. More specifically, this invention relates to automated biopsy instruments especially useful for improving minimally invasive medical procedures to obtain soft tissue biopsy samples. 
     BACKGROUND OF THE INVENTION 
     A soft tissue biopsy procedure is a medical procedure for removing a soft tissue sample from a human or animal. The tissue sample can be analyzed to assist a medical professional in formulating a diagnosis. The biopsy procedure is a minimally invasive procedure for obtaining the tissue sample. 
     The biopsy procedure can be performed utilizing various techniques and devices. Typically, a biopsy device includes an inner stylet slidably positioned inside an outer cannula. The stylet is a solid, pointed needle having a tissue sampling recess, and the cannula is a hollow, open ended needle having a sharp tip. The stylet and the cannula are manipulated to capture a tissue sample in the sample recess. Existing biopsy devices include manual, semi-automated, and automated devices. 
     Manual biopsy devices allow for manual movement of the stylet and the cannula. Initially, the stylet and the cannula are inserted into soft tissue with the cannula covering the stylet tissue recess. Next, the stylet is manually advanced into the soft tissue to expose the tissue recess and to allow tissue to prolapse into the recess. The cannula is then manually advanced to sever the tissue and capture a tissue sample within the recess. Next, the stylet or the entire the biopsy device is withdrawn from the patient and the tissue sample removed from the recess. 
     Existing manual biopsy devices have exhibited drawbacks. For example, manual devices require the use of two hands to advance the stylet while holding the cannula in position, and to hold the stylet in position while advancing the cannula. This biopsy technique requires great manual dexterity and coordination. Further, the cutting speed of the manually advanced cannula is quite slow which may result in a poor quality tissue sample. 
     Existing semi-automatic biopsy devices provide stylet and cannula advancement motions similar to manually operated devices. After the stylet is manually advanced, the semi-automatic devices typically include a compression spring that advances the cannula to capture a tissue sample. The semi-automatic devices still require manual manipulation of the stylet. 
     Existing automatic biopsy devices also provide stylet and cannula advancement motions to capture a tissue sample in a stylet sample recess. The automatic devices generally include two compression springs to advance the stylet and the cannula. A first compression spring advances the stylet forward after a firing button is depressed. A second compression spring subsequently advances the cannula forward to sever and capture a tissue sample. Existing automatic devices have exhibited drawbacks. For example, automatic devices have required the use of two hands to cock the device (compress the springs). One device purports to be cockable with a single hand; but, the hand must change positions after cocking the cannula in order to cock the stylet. Changing hand positions is cumbersome and encourages two handed cocking. Additionally, as a compression spring expands, the spring force decreases. As the spring force decreases, the stylet and cannula speeds decrease, which may compromise the quality of the tissue sample. Also, existing automatic devices have provided insufficient time to allow the tissue to relax into the sample recess. Consequently, the size of the tissue sample may be reduced. 
     Existing biopsy devices have been designed to be either reusable or disposable. The reusable devices include a reusable handle and disposable needle assemblies. The stylet and cannula are removable from the handle and disposable with a new stylet and cannula. The handle can be cleaned and re-sterilized after use and thus, is reusable. Disposable devices include a permanent stylet and cannula and are not re-sterilizable. Accordingly, disposable devices are used on a single patient and then discarded. 
     Examples of existing biopsy devices are disclosed in U.S. Pat. Nos. 4,600,014; 4,944,308; 4,958,625; 5,368,045; and Re34,056. A reusable automatic device containing a single spring for stylet and cannula advancement is disclosed in U.S. Pat. No. 5,121,751. 
     Therefore, needs exist to improve biopsy devices. Particularly, needs exist to improve automated biopsy instruments especially useful for minimally invasive medical procedures to obtain soft tissue biopsy samples. The present invention satisfies these and other needs to improve biopsy devices. 
     Other aspects and advantages of the present invention will become apparent after reading this disclosure, including the claims, and reviewing the accompanying drawings. 
     SUMMARY OF THE INVENTION 
     The present invention provides automated biopsy instruments especially useful for improving minimum invasive medical procedures to obtain soft tissue biopsy samples. The biopsy instruments provide side-by-side actuators which retract a stylet and a cannula in specific sequences. The retraction sequences include cannula retraction with subsequent stylet retraction, and simultaneous cannula and stylet retraction. The side-by-side design of the cannula and stylet actuators allow the biopsy instrument to be operated with a single human hand without repositioning the hand 
     The biopsy instruments may include a single spring or two springs to sequentially fire the stylet and the cannula. A constant force spring is utilized in the single spring embodiment. The single spring embodiment also includes an engagement mechanism connected to the constant force spring. The engagement mechanism first fires the stylet, initiates concurrent cannula firing, and then completes cannula firing. The biopsy device provides a time delay to allow tissue to more effectively prolapse into the stylet tissue sample recess. 
     A safety cover is also provided to prevent accidental firing of the biopsy instrument. 
    
    
     BRIEF DESVRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a biopsy instrument made in accordance with the principles of the present invention. 
     FIG. 2 is a cross-sectional, perspective view of a biopsy instrument made in accordance with the principles of the present invention. 
     FIG. 3 is a cross-sectional view of the biopsy instrument of FIG. 2 in a cannula retracted mode. 
     FIG. 4 is a cross-sectional view of the biopsy instrument of FIG. 2 in a cannula and stylet retracted mode. 
     FIG. 5 is an enlarged, cross-sectional view of an interlocking mechanism. 
     FIG. 6 is an exploded, perspective view of an alternative embodiment of a biopsy instrument made in accordance with the principles of the present invention. 
     FIG. 7 is a perspective view of another alternative embodiment of a biopsy instrument made in accordance with the principles of the present invention. 
     FIG. 8 is a perspective view of the biopsy instrument of FIG. 7 in a cannula retracted mode. 
     FIG. 9 is a perspective, partial cross-sectional view of the biopsy instrument of FIG. 7 in a cannula and stylet retracted mode. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Although the present invention can be made in many different forms, the preferred embodiments are described in this disclosure and shown in the attached drawings. This disclosure exemplifies the principles of the present invention and does not limit the broad aspects of the invention only to the illustrated embodiments. 
     FIG. 1 shows a perspective view of a biopsy instrument  10  made in accordance with the principles of the present invention. The biopsy instrument  10  includes a housing  12  having a left housing  14  and a right housing  16 . The housing could be made from other components, for example, an upper housing and a lower housing as shown in FIG.  6 . Referring to FIG. 1, preferably, the housing  12  is ergonomically designed to conform to the human hand and may include one or more finger rests  18 . The ergonomic design includes a housing shape that coincides with contours of the human hand and is comfortable to hold. The biopsy instrument  10  also includes a cannula actuator  30 , a stylet actuator  32 , and a safety cover  34  as described below. 
     A cannula  20  and a stylet  22  are slidably contained within the housing  12  and extend out of an opening  24  in a housing end  26 . The cannula  20  is a hollow needle having a sharp, open end. The stylet  22  is a solid needle having a pointed end and a tissue sample recess  28 . The recess  28  is shown in FIG.  3 . The stylet  22  is slidably positioned within the cannula  20  and extends beyond the cannula end, 
     FIG. 2 shows a cross-sectional, perspective view of a biopsy instrument  10  made in accordance with the principles of the present invention. The cannula  20  and the stylet  22  are permanently attached to two self-guided slides, a cannula slide  36  and a stylet slide  38 , respectively. The cannula and stylet slides  36 ,  38  are axially slidable on a guide  40  connected to the housing  12 . There may be two guides  40 , one guide  40  on each half of the housing. The stylet slide  38  is slidable between a rear stop block  42  and a middle stop block  44 , and the cannula slide  36  is slidable between the middle stop block  44  and a front stop block  46 . The front, middle, and rear stop blocks  42 ,  44 ,  46  are permanently secured to the housing  12  at their respective locations. 
     Accordingly, the stylet slide  38  is slidable between a first position adjacent the rear stop block  42  and a second position adjacent the middle stop block  44 . The cannula slide  36  is slidable between a first position adjacent the middle stop block  44  and a second position adjacent the front stop block  46 . When the stylet slide  38  and the cannula slide  36  are in their first positions, a portion of the stylet  22  and a portion of the cannula  20  are retracted into the instrument  10 . When the stylet slide  38  and the cannula slide  36  are in their second positions, the stylet  22  and cannula  20  are advanced out of the instrument  10 . 
     A constant force spring  48  provides the driving force for the stylet  22  and the cannula  20 . The constant force spring  48  maintains a constant speed of travel for both the stylet  22  and the cannula  20 . The constant force spring  48  is a rotatable and flexible spring coil. Also one or more constant force springs  48  can be utilized by connecting the multiple springs at their non-coiled ends. Accordingly, multiple springs  48  having relatively small coil diameters can be utilized to supply the same force as a single spring  48  having a relatively larger coil diameter. The Coiled end of the spring.  48  is secured to the housing  12  and the free end of the-spring  48  slidably extends through a passageway  50  in the cannula slide  36  and is attached to an engagement mechanism  52 . 
     The engagement mechanism  52  includes an interlock end  54  and a cam surface  56 . The cam surface  56  of the engagement mechanism  52  cams along a ramp  58  to alternatively interlock and release the interlock end  54  with the stylet slide  38  as described in detail below. The engagement mechanism  52  may include multiple cam surfaces  56  that cam along multiple spaced apart ramps  58 , as shown more clearly in FIG. 6, for example. 
     Referring to FIG. 2, the cannula actuator  30  and the stylet actuator  32  are independent and slidably extend along the housing  12  and through a housing opening  60 . The stylet actuator  32  and the cannula actuator are juxtaposed. Particularly, the cannula actuator  30  and the stylet actuator  32  are positioned side-by-side each other to permit actuation of both actuators  30 ,  32  by a single finger of a single hand without repositioning the hand. The actuators  30 ,  32  provide a mechanism to place the biopsy device  10  in a ready mode as described in detail below. The actuators  30 ,  32  include a finger surface  62  which can be contacted by a single finger of a single human hand to actuate (slide) the actuators  30 ,  32 . A projection  64  on the stylet slide  38  engages the stylet actuator  32 . Likewise, a projection  66  on the cannula slide  36  engages the cannula actuator  30 . 
     A spring loaded firing trigger  68  is provided at a distal end  70  of the instrument  10  opposite of the proximal front end  26 . The firing trigger  68  is pressed to fire the instrument  10 . Particularly, the firing trigger  68  fires and releases the stylet  22  as described below. The hinged safety cover  34  (shown in FIG. 1) is provided to prevent accidental firing of the instrument. The safety cover  34  can be moved between a first position covering the firing trigger  68  and a second position allowing access to the firing trigger  68 . The firing trigger  68  could be placed at any location on the instrument  10 , including the proximal front end, and an appropriate mechanism provided to fire the instrument  10 . 
     Operation of the biopsy instrument  10  will be described with reference to FIGS. 2-5. Initially, FIG. 2 shows the instrument  10  in a fired mode. The biopsy instrument  10  is placed in a ready mode by holding the instrument  10  in a single hand in a first position and actuating the cannula actuator  30  and the stylet actuator  32  to retract the cannula  20  and the stylet  22 . 
     Referring to FIG. 3, a cross-sectional view of the biopsy instrument  10  in a cannula retracted mode is shown. First, the cannula actuator  30  is retracted rearwardly by a finger of the same single hand contacting the finger surface  62 . The cannula actuator  30  engages the projection  66  on the cannula slide  36  and slides the cannula slide  36  and the cannula  20  rearwardly against the force of the constant force spring  48 . The engagement mechanism  52  is abutted against the cannula slide  36  and thus, the spring  48  is uncoiled as the cannula actuator  30  is actuated. 
     FIG. 5 shows an enlarged, cross-sectional view of an interlocking mechanism in three stages. The first stage is shown where the cannula slide  36  retracts, the cam surface  56  of the engagement mechanism  52  is advanced and elevated along a first cam surface  58   a  of the ramp  58 . The second stage is when the cam surface  56  slides along a horizontal ramp surface  58   c . The interlock end  54  of the engagement mechanism  52  is guided into a lock  72  on the stylet slide. The third stage is shown as the engagement mechanism cam surface  56  advances and descends along a second cam surface  58   b  of the ramp  58 ; the interlock end  54  releasably locks to the lock  72  of the stylet slide  38 . 
     Referring to FIG. 3, the cannula slide  36  contacts a first stylet latch  74  and releases the stylet slide  38  from being latched to the middle stop block  44 . The first stylet latch  74  is shown in FIG. 4 unlatched to the middle stop block  44 . As shown in FIG. 3, a cannula latch  76  latches the cannula slide  36  to the middle stop block  44 . In this position of the instrument  10 , the cannula  20  is retracted and the stylet tissue sample recess  28  is exposed. If a tissue sample had previously been captured within the recess  28 , the tissue sample could now be expelled. 
     Referring to FIG. 4, a cross-sectional view of the biopsy instrument  10  in a cannula and stylet retracted mode (instrument ready for firing mode) is shown. Second, while the same single hand remains in its first position on the instrument  10 , the stylet actuator  32  is retracted rearwardly by the same finger contacting the finger surface  62  on the stylet actuator  32 . The stylet actuator  32  engages the projection  64  on the stylet slide  38  and slides the stylet slide  38  and the stylet  22  rearwardly against the force of the constant force spring  48 . The engagement mechanism  52  is locked to the stylet slide  38  and thus, the spring  48  is further uncoiled as the stylet actuator  32  is actuated. A second stylet latch  78  latches the stylet slide  38  to the rear stop block  42 . In this position of the instrument  10 , both the cannula  20  and the stylet  22  are retracted and the biopsy instrument  10  is ready for firing. 
     In the ready mode, the stylet  22  and the cannula  20  are inserted into a patient in the area where a tissue sample is desired. 
     The biopsy instrument  10  is fired by moving the safety cover  34  at the rear end  70  of the housing  12  away from the spring loaded trigger  68  and depressing the trigger  68 . The trigger  68  releases the second stylet latch  78  and the spring  48  propels the stylet slide  38  and the stylet  22  forward extending the stylet  22  into the tissue. The stylet recess  28  is exposed and the tissue prolapses into the recess  28 . The stylet slide  38  advances forward until it contacts the middle stop block  44 , and at that point the first stylet latch  74  latches onto the middle stop block  44 . The first stylet latch  74  latches onto the middle stop block  44  to prevent the stylet  22  from recoiling as the cannula  20  advances forward. 
     As the stylet slide  38  approaches the middle stop block  44 , the stylet slide  38  impacts the cannula latch  76  and moves the cannula latch  76  radially outward and axially forward. The forward axial movement of the cannula latch  76  initiates forward movement of the cannula slide  36  and the cannula  20  simultaneously and concurrently with the forward travel of the stylet  22 . 
     As the stylet slide  38  approaches the middle stop block  44 , the cam surface  56  of the engagement mechanism  52  is elevated along the ramp second cam surface  58   b . After the cannula  20  has started its forward motion, the interlock end  54  is elevated sufficiently to be released from the stylet slide lock  72 . 
     The engagement mechanism  52  continues to travel forwardly under the force of the spring  48  and abuts the cannula slide  36 . The constant force spring  48  advances the cannula slide  36  and the cannula  22  until the cannula slide  36  contacts the front stop block  46 . After the concurrent stylet  22  and cannula  20  motion, the cannula  20  briefly stops until the spring  48  resumes movement of the cannula  20 . For example, there may be approximately a millisecond time delay. The time delay provided by the engagement mechanism  52  and the ramp  58  allows additional time for the tissue to prolapse into the stylet recess  28 . 
     As the cannula  20  advances over the stylet  22 , the cannula  20  severs the tissue and captures a tissue sample within the recess. After the tissue sample is captured, the biopsy instrument  10  is removed from the patient. The cannula  20  can be retracted as discussed above to expose the tissue sample and remove the sample from the biopsy instrument  10 . 
     The biopsy instrument  10  only permits a specific actuation sequence of the cannula  20  and the stylet  22 . The cannula  20  must be retracted prior to retraction of the stylet  22  because in the fired mode, the stylet slide  38  is latched to the middle stop block  44 . The stylet slide  38  is unlatched from the middle stop block  44  only by the cannula slide  36  contacting the first stylet latch  74 . This prevents a captured tissue sample from being dragged along the inside of the cannula  20  and damaged. In other words, the cannula actuator  30  is actuated independently of the stylet actuator  32 , and subsequently the stylet actuator  32  is actuated. The cannula actuator  30  and the stylet actuator  32  return to their forward positions as shown in FIG. 1 as the stylet  22  and the cannula  20  are fired. 
     FIG. 6 shows an exploded, perspective view of an alternative embodiment of a biopsy instrument  10  made in accordance with the principles of the present invention. Components of the alternative biopsy instrument  10  shown in FIG. 6 are identified by the same reference numerals as used in FIGS. 1-5. 
     The biopsy instrument  10  shown in FIG. 6 includes an upper housing  14  and a lower housing  16 . A guide  40  is a separate component from the housing. The stylet slide  38  and the cannula slide  36  slide along the guide  40 . The front stop block  46 , the middle stop block  44 , and the rear stop block  42  are attached to the guide  40  in their respective locations. The cannula actuator  30  and the stylet actuator  32  slide on an actuator support  80 . The actuator support  80  includes two slots  82 ,  84 . The projection  64  on the stylet slide  38  extends through and slides along the slot  82  such that the stylet actuator  32  engages the stylet slide  38 . Likewise, the projection  66  on the cannula slide  36  extends through and slides along the slot  84  such that the cannula actuator  30  engages the cannula slide  36 . 
     FIG. 7 shows a perspective view of the internal components of an alternative embodiment of a biopsy instrument  100  made in accordance with the principles of the present invention. Components of the alternative biopsy instrument  100  which are similar to the components in biopsy instrument  10  of FIG. 2 are identified by corresponding numerals in the  100  series. 
     The biopsy instrument  100  includes two springs, a stylet spring  186  and a cannula spring  188 . The stylet spring  186  is positioned between the rear stop block  142  and the stylet slide  138 , and biases the stylet slide  138  forward. Likewise, the cannula spring  188  is positioned between the middle stop block  144  and the cannula slide  136 , and biases the cannula slide  136  forward. In the fired mode, as shown in FIG. 7, the springs  186 ,  188  constantly exert forward biasing forces on the slides  138 ,  136 . Accordingly, the first stylet latch on the stylet slide  138  has been removed because the stylet spring  186  prevents the stylet  122  from recoiling when the cannula  120  is fired. 
     The biopsy instrument  100  can be placed in a ready mode by actuating the cannula actuator  130  and the stylet actuator  132  in three different sequences. Referring to FIGS. 7-9, the first actuating or cocking sequence is the same as described above with reference to the instrument  10  shown in FIGS. 2-4 in which the cannula actuator  130  is actuated first and independently of the stylet actuator  132 , and subsequently the stylet actuator  132  is actuated. 
     Referring to FIG. 9, the second actuating sequence is simultaneous actuation of the cannula actuator  130  and the stylet actuator  132  by a single finger while the finger contacts both actuators  130 ,  132  simultaneously. The single finger of the single hand is simultaneously placed on both of the finger surfaces  162 . The side-by-side location of the actuators  130 ,  132  allows for the single finger to contact both of the finger surfaces  162 . As the single finger actuates both actuators  130 ,  132 , the stylet  122  and cannula  120  are retracted simultaneously. 
     The third actuating sequence also simultaneously actuates the cannula actuator  130  and the stylet actuator  132 . The third sequence includes a single finger contacting only the finger surface  162  of the stylet actuator  132 . Referring to FIGS. 7 and 9, as the stylet actuator  132  is actuated, a wall  190  on the stylet actuator  132  engages a projection  192  on the cannula actuator  130 . The projection  192  is shown in FIG.  8 . Accordingly, as the stylet actuator  132  slides rearwardly, the cannula actuator  130  simultaneously slides rearwardly. 
     Regardless of which actuation sequence is utilized for the instrument shown in FIGS. 7-9, the stylet  122  cannot be retracted prior to retraction of the cannula  120 . This prevents a captured tissue sample from being dragged along the inside of the cannula  120  and damaged. The three actuating sequences provide medical personnel with flexibility in placing the biopsy instrument  100  in a ready mode, while, preventing retraction of the stylet  122  prior to retraction of the cannula  120 . 
     While the preferred embodiments have been illustrated and described, numerous changes and modifications can be made without significantly departing from the spirit and scope of this invention. Therefore, the inventors intend that such changes and modifications be covered by the appended claims.