Abstract:
A biopsy device includes an outer cannula, an inner rod, a sheath operably associated with the outer cannula, a handle assembly removably attachable to the sheath, and a release member for releasably attaching the handle assembly to the sheath. In one embodiment, a locking element associated with the sheath comprises a pair of notches located on either side of the sheath, and a locking element associated with the handle assembly comprises a pair of slots in communication with an opening within the handle assembly. The release member comprises a rotatable collar located in a channel on the handle assembly. When the release member is rotated from a first position to a second position, a portion thereof protrudes through the slots into the notches on the sheath, thereby locking the sheath in place.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates in general to biopsy devices and, more particularly, to a biopsy device with a removable handle assembly. 
     2. Background Art 
     Biopsy devices have been known in the art for many years. In particular, many such biopsy devices have included a hollow outer cannula with some form of inner rod slidable within the outer cannula. The outer cannula conventionally consists of a proximal end, a distal end, and some form of a handle associated with the proximal end. The inner rod may typically take several different forms, including a sharpened stylet for insertion of the biopsy device into a patient, an inner cannula for sampling tissue, and/or an ejector rod for forcing the sample out of the outer cannula. The inner rod also typically includes a second or connection handle which may be secured to the handle portion of the outer cannula. 
     Such devices typically provide for the securable joining together of the outer cannula and inner rod handles when the inner rod is inserted within the outer cannula. Once the entire assembly is inserted within a patient, the inner rod is typically removed by separating the outer cannula and inner rod handles, and removing the inner rod by means of the inner rod handle. This type of structure is disclosed by Baldridge, U.S. Pat. No. 5,357,974, Tretinvak, U.S. Pat. No. 4,403,617, Tretinvak, U.S. Pat. No. 4,630,616, Lee, U.S. Pat. No. 4,655,266, and Strasser, et al., U.S. Pat. No. 4,838,282, among others. 
     Many of these types of devices require rotation of one of the handles themselves to unlock and separate the handles from one another, resulting in a change of orientation of the handles with respect to one another while the device is within the patient. This change in orientation of the handles, however, can often cause a corresponding change in the orientation of the inner rod with respect to the outer cannula, which can be undesirable to the user. Likewise, the manipulations of the overall device while in use can inadvertently separate the cannula handle from the rod handle, unlocking the device and causing the aligned tips of the cannula and rod to become misaligned. Other such devices contain a locknut securing device positioned directly atop the inner rod, which must be repeatedly rotated in order to remove the inner rod, thereby allowing the user to directly remove the rod itself from the interior of the cannula. 
     One application in which such devices are used is to repair crushed vertebrae. Typically, the cannula and rod portions of the biopsy device are inserted within the patient in order to locate the proper vertebra. After the cannula has been positioned within a vertebra, then an imaging device, such as an x-ray machine, is used to view the location of the cannula tip to determine whether it is positioned properly. If the cannula is not in the desired position, then the position of the biopsy device is adjusted as needed. Once it is determined that the cannula is positioned properly, then the inner rod is removed, and a form of cement or other binding element is injected into the vertebra through the cannula in order to reexpand the crushed vertebra. The devices in the prior art, however, present a particular disadvantage for this type of application. Once the user has removed the inner rod, along with its corresponding handle, the outer cannula handle remains in place, providing an undesired impediment to the imaging process. 
     It is therefore desired to provide a biopsy device with a separate handle assembly which is capable of being removed after the device is inserted into a patient, leaving the outer cannula and inner rod in place in the desired location, thereby eliminating the impediment to the imaging process presented by the presence of the outer cannula handle, as described above. 
     It is further desired to provide a biopsy device which allows the user to readily unlock and remove the handle assembly without affecting the orientation of the outer cannula and the inner rod with respect to one another, in order to prevent an undesired corresponding change in orientation of the distal ends of each. 
     Another object of the invention is to provide a biopsy device having a threaded region for the connection of external devices to the outer cannula, thereby allowing the outer cannula to be used with any number of medical devices requiring access to interior regions of the body. 
     It is also an object of the invention to provide a biopsy device in which the handle assembly may be resterilized after use and reused, resulting in significant cost savings over similar devices with attached handles which are disposed along with the rest of the device after use. 
     These and other objects of the present invention will become apparent in light of the present specification, claims, and drawings. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a biopsy device having a removable handle for alternatively attaching and removing a handle assembly while the cannula portion of the device is inserted into a patient, without affecting the orientation of the cannula portion of the device within the patient. The biopsy device comprises an outer cannula having a proximal end, a distal end, and a substantially hollow cross-section between the proximal and distal ends; an inner rod capable of being telescopically inserted into and retracted from the outer cannula and having a proximal end and a distal end; a sheath operably associated with and surrounding at least a portion of the outer cannula, and comprising a locking element; a handle assembly removably attachable to the sheath comprising a locking element and an opening for receiving at least a portion of the sheath; and a release member for releasing the handle assembly from attachment to the sheath by interacting with the locking elements associated with the sheath and the handle assembly. Further, the sheath may be at least partially inserted within the opening in the handle assembly and attached thereto, thereby retainably, yet releasably, locking the handle assembly to the outer cannula and the inner rod. 
     In another embodiment of the invention, the release member is a release element which is capable of toggling by the user between at least two positions in order to alternatively lock and release the handle assembly to the sheath. 
     In a further embodiment, the locking element associated with the sheath comprises at least one slot on the sheath which is capable of interacting with the release member to prevent separation of the sheath and the handle assembly. 
     In a still further embodiment, the locking element associated with the handle assembly comprises at least one aperture in the handle assembly which is capable of interacting with the release member to prevent separation of the sheath and the handle assembly. 
     In a yet further embodiment, the release member comprises a rotatable collar associated with at least one of the sheath and the handle assembly, and which is capable of being rotated at least partially about the sheath and the handle assembly when the two are joined together. The rotatable collar has at least two stationary positions, so that when the collar is in one position, a portion of the collar interacts with both of the locking elements associated with the sheath and the handle assembly to prevent separation of the sheath and the handle assembly. When the collar is in the other position, it avoids interaction with both of the locking elements, thereby permitting separation of the sheath and handle assembly from one another. 
     In an alternative embodiment, the release member comprises a slide member associated with at least one of the sheath and the handle assembly, and which is capable of lateral movement relative to the sheath and the handle assembly when the two are joined together. The slide member has at least two stationary positions, so that when the slide member is in one position, a portion of the slide member interacts with both of the locking elements associated with the sheath and the handle assembly to prevent separation of the sheath and the handle assembly. When the slide member is in the other position, it avoids interaction with both of the locking elements, thereby permitting separation of the sheath and handle assembly from one another. 
     In another embodiment of the invention, the opening in the handle assembly for receipt of the sheath is asymmetrical about at least one axis substantially perpendicular to the longitudinal axis of the opening. 
     In a further embodiment, at least a portion of the sheath has an asymmetrical cross-section substantially similar to that of the asymmetrical opening in the handle assembly, so as to be insertable into the handle assembly only when the sheath and the handle assembly are aligned in one particular orientation. This ensures that the outer cannula and the inner rod will be aligned in the same particular orientation relative to the handle assembly when the sheath and the handle assembly are locked together. 
     In still another embodiment of the invention, at least a portion of the outer surface of the sheath is threaded to enable the attachment of a comparably threaded component of a separate conduit for attachment to the outer cannula after the handle assembly is removed from the sheath. 
     An additional embodiment of the invention further includes an attachment member for securably attaching the inner rod within the outer cannula. 
     In a further embodiment, the attachment member comprises at least one prong associated with the inner rod for engaging with the sheath to securably attach the inner rod within the outer cannula. 
     Yet another embodiment includes a locking indicia for readily indicating whether the sheath and the handle assembly are in a locked or an unlocked orientation, relative to one another. 
     In alternative embodiments of the invention, the inner rod may comprise at least one of an inner cannula, a stylet, an obturator and an ejector rod. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 a  is a perspective view of the biopsy device according to the present invention, showing the handle assembly portion of the device lockably attached to the sheath portion. 
     FIG. 1 b  is an exploded perspective view of the biopsy device shown in FIG. 1 a.    
     FIG. 2 is a front elevational view of the biopsy device shown in FIG. 1 a.    
     FIG. 3 is a side elevational view of the biopsy device shown in FIG. 1 a.    
     FIG. 4 is an elevated cross-sectional view of the biopsy device shown in FIG. 1 a  taken along lines B—B of FIG. 2, and looking in the direction of the arrows. 
     FIG. 5 is an elevated cross-sectional view of the biopsy device shown in FIG. 1 a  taken along lines A—A of FIG. 3, and looking in the direction of the arrows. 
     FIG. 6 a  is a perspective view of the lower portion of the handle body of the biopsy device shown in FIG. 1 a , showing the sheath housing within the handle body. 
     FIG. 6 b  is a front elevational view of the lower portion of the handle body shown in FIG. 6 a.    
     FIG. 6 c  is a side elevational view of the lower portion of the handle body shown in FIG. 6 a.    
     FIG. 6 d  is a top plan view of the lower portion of the handle body shown in FIG. 6 a.    
     FIG. 6 e  is a cross-sectional bottom plan view of the lower portion of the handle body shown in FIG. 6 a  taken along lines A—A of FIG. 6 b , and looking in the direction of the arrows. 
     FIG. 7 a  is a perspective view of the sheath portion of the biopsy device shown in FIG. 1 a.    
     FIG. 7 b  is a front elevational view of the sheath portion shown in FIG. 7 a.    
     FIG. 7 c  is a side elevational view of the sheath portion shown in FIG. 7 a.    
     FIG. 7 d  is a top plan view of the sheath portion shown in FIG. 7 a.    
     FIG. 8 a  is a perspective view of the release member of the biopsy device shown in FIG. 1 a.    
     FIG. 8 b  is a front elevational view of the release member shown in FIG. 8 a.    
     FIG. 8 c  is a top plan view of the release member shown in FIG. 8 a.    
     FIG. 8 d  is a side elevational view of the release member shown in FIG. 8 a.    
     FIG. 9 a  is a perspective view of the lower portion of the handle body of the biopsy device according to another embodiment of the present invention. 
     FIG. 9 b  is a front elevational view of the lower portion of the handle body shown in FIG. 9 a.    
     FIG. 9 c  is a side elevational view of the lower portion of the handle body shown in FIG. 9 a.    
     FIG. 9 d  is a top plan view of the lower portion of the handle body shown in FIG. 9 a.    
     FIG. 9 e  is a cross-sectional elevated side view of the lower portion of the handle body shown in FIG. 9 a  taken along lines A—A of FIG. 9 b , and looking in the direction of the arrows. 
     FIG. 9 f  is a cross-sectional elevated side view of the lower portion of the handle body shown in FIG. 9 a  taken along lines B—B of FIG. 9 b , and looking in the direction of the arrows. 
     FIG. 9 g  is a cross-sectional elevated front view of the lower portion of the handle body shown in FIG. 9 a  taken along lines C—C of FIG. 9 b , and looking in the direction of the arrows. 
     FIG. 9 h  is a cross-sectional top plan view of the lower portion of the handle body shown in FIG. 9 a  taken along lines D—D of FIG. 9 b , and looking in the direction of the arrows. 
     FIG. 10 a  is a perspective view of the sheath portion of the embodiment shown in FIG. 9 a.    
     FIG. 10 b  is a front elevational view of the sheath portion shown in FIG. 10 a.    
     FIG. 10 c  is a side elevational view of the sheath portion shown in FIG. 10 a.    
     FIG. 10 d  is a top plan view of the sheath portion shown in FIG. 10 a.    
     FIG. 11 a  is a perspective view of the release member of the embodiment shown in FIG. 9 a.    
     FIG. 11 b  is a front elevational view of the release member shown in FIG. 10 a.    
     FIG. 11 c  is a top plan view of the release member shown in FIG. 10 a.    
     FIG. 11 d  is a side elevational view of the release member shown in FIG. 10 a.    
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While this invention is susceptible of embodiment in many different forms, there is shown in the drawings, and will herein be described in detail, several specific embodiments, with the understanding that the present disclosure can be considered as an exemplification of the principals of the invention and is not intended to limit the invention to the embodiments illustrated. 
     Biopsy device  20  is shown in FIGS. 1-8 as comprising outer cannula  22 , inner rod  24 , sheath  26 , handle assembly  28 , and release member  30 . Outer cannula  22  comprises a cylindrical tube, preferably fashioned from stainless steel or other metal, having distal end  34 . While outer cannula  22  is shown here as having a flush distal end  34 , distal end  34  may also comprise a saddle point or other configuration conducive to cutting through human tissue. Moreover, distal end  34  may also include an inner tapered portion to facilitate retrieval of tissue, such as disclosed in Mittermeier, U.S. Pat. No. 6,063,037. 
     Inner rod  24  is shown in FIGS. 4 and 5 as comprising a cylindrical rod contained within outer cannula  22 , having distal end  44 , and an attachment member  46 . Attachment member  46  includes prongs  48 , which are preferably flexible and biased inward, for attachment of inner rod  24  to sheath  26 , and proximal end  49 . Attachment member  46  typically has the same cross-sectional shape as barrel portion  52  of sheath  26 , so that inner rod  24  and outer cannula  22  may be joined to handle assembly  28 , as described below. While inner rod  24  is shown here as being shorter than outer cannula  22  and having a blunt distal end  44 , typically inner rod  24  will be longer than outer cannula  22  and will have a sharpened stylet or obturator which protrudes from outer cannula  22  for cutting through human tissue. Additionally, inner rod  24  may also comprise a hollow inner cannula for sampling tissue, an ejector rod for forcing tissue from outer cannula  22 , as well as other types of inner rods commonly used with such biopsy devices known by those of ordinary skill in the art having the present disclosure before them. 
     Sheath  26  is shown in FIGS. 7 a - 7   d  as comprising base portion  50 , barrel portion  52  and thread  54 . Sheath  26  surrounds outer cannula  22 , and is preferably constructed from plastic or similar material. Sheath  26  progressively decreases in width from bottom to top, with base portion  50  having the largest width, and barrel portion  52  and thread  54  being successively smaller in width. Barrel portion  52  includes locking elements thereon, namely notches  56  on either side thereof for interacting with release member  30 , as described below. Thread  54  includes notches  58  which facilitate the connection of inner rod  24  and outer cannula  22 . When inner rod  24  is inserted within outer cannula  22 , prongs  48  encounter thread  54  and are bent slightly outward. When prongs  48  have passed over thread  54 , they return to their unbent position, coming to rest within notches  58 . Because prongs  48  are biased inward, they are therefore held in place in notches  58 , thereby securing inner rod  24  in place relative to outer cannula  22 . Because prongs  48  are flexible, however, inner rod  24  can be easily separated from outer cannula  22  by pulling on attachment member  46 , which causes prongs  48  to encounter thread  54  and bend outward. 
     Thread  54  is also adapted for the connection of external medical devices to outer cannula  22  by means of a threaded connector. These may include devices for suction, devices for injecting matter into a body cavity, endoscopic devices for examining the interior of the body, and any other devices which would be obvious to one of ordinary skill in the art. This feature allows the user of the biopsy device to accomplish multiple tasks in a particular region of the body without having to insert a separate needle for each task. 
     Handle assembly  28  is shown in FIGS. 1 a ,  1   b ,  2 ,  3 ,  5 , and  6   a - 6   e  as comprising handle body  60 , opening  66 , channel  68 , sheath housing  70 , and insert hole  72 . Handle body  60  comprises upper portion  62 , lower portion  64 , and neck portion  65 . In this embodiment, upper portion  62  and lower portion  64  are separate pieces, joining together at seam  63 . However, this separation of handle body  60  into two components is solely to facilitate the molding of handle body  60 , and is not necessary to practice the invention. Upper portion  62  further includes stop  61 , which constitutes an inward projection that is aligned with the proximal end of sheath housing  70 , to restrain the position of proximal end  49  of attachment member  46  and ensure orientation of inner rod  24  with outer cannula  22 . Opening  66  leads into sheath housing  70 , which extends vertically through the interior of handle body  60 , and which includes side portions  67 . Sheath housing  70  has the same cross-section as barrel portion  52  of sheath  26 , and holds barrel portion  52  in place when sheath  26  and handle assembly  28  are joined together. Insert hole  72  is adapted for the placement of a rubber insert (not shown) to absorb some of the force generated by the use of a hammer or similar device in connection with the insertion of biopsy device  20  into a patient, so as to minimize the amount of noise generated by the application of such force. 
     In the present embodiment, opening  66  has an oblong shape which is asymmetrical about the longer axis of handle assembly  28 , and which corresponds to the cross-sectional shape of barrel portion  52  of sheath  26 . As a result, opening  66  will receive barrel portion  52  only when sheath  26  and handle assembly  28  are aligned in the correct orientation. This design feature ensures that distal end  34  of outer cannula  22  and distal end  44  of inner rod  24  are aligned in a desired orientation relative to one another when sheath  26  and handle assembly  28  are joined together, and that sheath  26  and handle assembly  28  cannot be joined in any other orientation. 
     Channel  68  comprises a shallow channel on the outside of neck portion  65  which extends approximately three-quarters of the way around neck portion  65 . Channel  68  includes locking elements, namely slots  69  and  71 , which are located opposite from one another and open into side portions  67  of sheath housing  70 . When handle assembly  28  is viewed from the front, as in FIG. 6 b , slots  69  and  71  are located within channel  68  on the left and right-hand sides of neck  65 , respectively. Channel  68  begins at slot  71 , and extends counterclockwise approximately one-quarter revolution past slot  69 , terminating at the front of neck  65 . 
     Release member  30  is shown in FIGS. 8 a - 8   d  as a substantially flat, semicircular member having an aperture diameter slightly larger than the inner diameter of channel  68 , and which includes notch  80  and dimpled or knurled portion  82 , which provides a gripping surface to facilitate rotation of release member  30  by the user. Release member  30  is adapted to fit within channel  68  and has an outer circumference extending slightly less than three-quarters around neck portion  65 , so that release member  30  is able to be manipulated and rotate within channel  68  about a small angular displacement on the order of one-eighth of one rotation. This effectively allows for release member  30  to be toggled between two positions, which correspond to the locked and unlocked orientation of handle assembly  28 . When release member  30  is rotated counterclockwise as far as possible, no portions of release member  30  protrude through slots  69  and  71 , as a result of which side portions  67  of sheath housing  70  are unobstructed. This owes to the fact that, on the left-hand side of channel  68 , notch  80  is aligned with slot  69 , and on the right-hand side of channel  68 , the end  84  of release member  30  is located slightly counterclockwise of slot  71 . This position corresponds to the unlocked orientation of biopsy device  20 , as described below. Alternatively, when release member  30  is rotated clockwise as far as possible, notch  80  is no longer aligned with slot  69 , thereby causing a portion of release member  30  to protrude through slot  69  and obstruct one side portion  67  of sheath housing  70 . Additionally, the end  84  of release member  30  now protrudes through slot  71 , obstructing the other side portion  67  of sheath housing  70 . This position of release member  30  corresponds to the locked orientation of biopsy device  20 . 
     In order to join handle assembly  28  to sheath  26 , and thereby to outer cannula  22  and inner rod  24 , sheath  26  must first be inserted into opening  66  in handle assembly  28 . In order to do so, release member  30  must be in the unlocked position, in which notch  80  is aligned with slot  69 , in order to permit insertion of sheath  26 . If release member  30  is in the locked position, then side portions  67  will be obstructed by release member  30  as described above, thereby preventing full insertion of sheath  26 . Opening  66  will accommodate sheath  26  with or without inner rod  24  attached, owing to the fact that attachment member  46  of inner rod  24  and barrel portion  52  of sheath  26  have substantially identical cross-sections. When inserted, sheath  26  passes through opening  66  into sheath housing  70 , which is of a sufficient length to accommodate both barrel portion  52  and thread  54 . When barrel portion  52  is fully inserted into sheath housing  70 , base portion  50  will abut the bottom of neck portion  65  of handle assembly  28 , and notches  56  on barrel portion  52  will be aligned with slots  69  and  71 . 
     Once sheath  26  has been fully inserted into sheath housing  70 , the user may then lock handle assembly  28  to sheath  26  by rotating release member  30  clockwise. As release member  30  is rotated from its unlocked position to its locked position, sheath  26  is fixed in place within sheath housing  70 , due to the fact that the portions of release member  30  which protrude through slots  69  and  71  into notches  56  prevent sheath  26  from moving. Because sheath  26  is fixed in place, prongs  48  on inner rod attachment member  46  are held in place by the walls of sheath housing  70 , thereby ensuring that outer cannula  22  and inner rod  24  remain fixed in place relative to one another while sheath  26  and handle assembly  28  are locked together. Additionally, sheath  26  and handle assembly  28  are maintained in axial alignment, relative to one another, by proximal end  49  of attachment member  46 , which abuts stop  61  on upper portion  62  of handle assembly  28 , as shown in FIG. 5, thereby preventing inner rod (stylet)  24  from moving longitudinally within outer cannula  22 . This likewise ensures a matched grind between the distal ends of cannula  22  and rod  24 . Therefore, the user of biopsy device  20  can use a large amount of force, if necessary, to manipulate biopsy device  20  in order to penetrate tissue and/or bone, without undesired movement of the distal ends of outer cannula  22  and inner rod  24  relative to one another. 
     One application for which biopsy device  20  is particularly well-suited is that of repairing crushed vertebrae. In this type of application, inner rod  24  typically comprises a sharpened stylet, which is used to penetrate tissue in order to reach the vertebrae. Once outer cannula  22  and inner rod  24  have been positioned within the desired vertebra, handle assembly  28  is removed from sheath  26  by means of release member  30 , as described above, in order to facilitate use of an imaging device to view the vertebral region to determine whether the distal end  34  of outer cannula  22  is in the desired location. If it is determined that outer cannula  22  and inner rod  24  are not positioned as desired, then handle assembly  28  may be reattached to sheath  26  in order to reposition biopsy device  20 . Once outer cannula  22  and inner rod  24  have been placed in the desired position, then inner rod  24  may then be removed from outer cannula  22  by means of attachment member  46 . Cement or other desired material may then be injected into the vertebra through outer cannula  22  by means of attachment of an external component to thread  54  in order to inflate the crushed vertebra. When the procedure is complete, handle assembly  28  may then be reattached to sheath  26  in order to remove biopsy device  20  from the patient. 
     Another embodiment of the invention is shown in FIGS. 9-11. In this embodiment, the outer cannula and inner rod portions (not shown) are substantially identical to those in the embodiment of FIGS. 1-8. Lower portion  164  of handle assembly  128  is shown in FIGS. 9 a - 9   h  as comprising opening  166 , sheath housing  170 , slots  172  and  174 , and indicia  176 . Upper portion of handle assembly (not shown) is identical to upper portion  62  of the previous embodiment. As in the previous embodiment, the separation of handle assembly  128  into multiple parts is not necessary to practice the invention. Indicia  176  preferably comprises a visual indicator which indicates to the user whether handle assembly  128  is in the locked or unlocked orientation, which in this embodiment takes the form of two lines, with the letters “L” (for locked) and “U” for unlocked written above them. 
     Sheath  126  is shown in FIGS. 10 a - 10   d  as comprising base portion  150 , barrel portion  152 , and thread  154 . Barrel portion  152  includes notch  156 , which in this embodiment comprises a single notch located on the front side of barrel portion  152 , and thread  154  includes notches  158  for receipt of the prong portions of the inner rod, as in the previous embodiment. 
     Release member  130  is shown in FIGS. 11 a - 11   e  as comprising slide portion  180 , projection  182 , and connection member  184 . Release member  130  attaches to the front of handle assembly  128  such that release member  130  reciprocates along the front surface of handle assembly  128 . Slide portion  180  comprises a rectangular member with rounded ends which is flat on one side and has a raised midsection on the other side to facilitate manipulation by hand. Connection member  184  comprises a pair of flanges  186  protruding from the flat side of slide portion  180 . The flanges protrude through slot  174  on handle assembly  128 , and are restrained from being removed due to the fact that connection member  184  is wider than slot  174 , which serves to fixedly attach release member  130  to handle assembly  128 . Projection  182  comprises a parallelepiped-shaped structure with one corner cut off, which protrudes from the flat side of slide portion  180 . 
     Sheath  126  and handle assembly  128  are alternatively locked and unlocked by sliding release member  130  from its locked position to its unlocked position, and vice versa. Release member  130  is in the unlocked position when it is in its rightmost position. In this position, notch  156  on sheath  126  is aligned with the cut-out portion of projection  182 , as a result of which sheath  126  and handle assembly  128  may be easily separated merely by pulling them apart. When release member  130  is moved to its leftmost position, then projection  182  correspondingly translates to the left, causing a portion of projection  182  to protrude into notch  156 . When one attempts to remove handle assembly  128  from sheath  126 , projection  182  will exert a force on the side of notch  156 , preventing removal of handle assembly  128  from sheath  126 . As a result, the leftmost position of release member  130  corresponds to the locked position, due to the fact that sheath  126  and handle assembly  128  are securely attached to one another, while the rightmost position of release member  130  corresponds to the unlocked position. 
     Further, release member  130  interacts with indicia  176  to indicate whether the release member is in the locked or unlocked position, as shown in FIGS. 9 a  and  9   b . When release member  130  is in its rightmost, or unlocked, position, then the right end of release member is aligned with the right mark of indicia  176 , above which is written the letter “U”, for “unlocked”. Similarly, when release member  130  is in its leftmost, or locked position, the right end of release member  130  is aligned with the left mark of indicia  176 , above which is written the letter “L”, for “locked”. Thus, the user will be able to tell whether the release member  130  is in its locked or unlocked position merely by glancing at handle assembly  128 . 
     The foregoing description and drawings are merely to explain and illustrate the invention, and the invention is not limited thereto except insofar as the independent claims are so limited, as those skilled in the art with the present disclosure before them will be able to make modifications and variations therein without departing from the scope of the invention.