with reference to fig1 through 4 , a surgical device 10 is shown in accordance with a first embodiment of this invention . the device 10 is particularly intended and suitable for extraction procedures , in which biological materials are required to be surgically moved , manipulated and / or extracted from a cavity of the human body . as such , the device 10 can be adapted for use as , for example , a urological , gynecological , cardiological , laparoscopical , or gastrointestinal instrument . the extraction device 10 is depicted as comprising a sheath 12 , legs 14 that project from a passage within the sheath 12 , and a cable 18 ( or other suitable actuating member ) for deploying the legs 14 from the sheath 12 once the distal end of the device 10 is properly positioned within a body cavity for the intended procedure , and then maintaining the positions of the legs 14 within the body cavity while the sheath 12 is advanced over the legs 14 to collapse them . a distal portion 16 of the cable 18 projects from the sheath 12 so as to be surrounded by the legs 14 , as seen in fig1 and 4 . the sheath 12 can be formed of any suitable material known in the art . the passage within the sheath 12 can be sized to be sufficiently large to not only accommodate the legs 14 and cable 18 , but also provide an irrigation or injection lumen , or a channel for a laser fiber to be passed through so that stones and other biological materials can be captured , held and fragmented to allow the resulting fragments to pass . the sheath 12 may also be equipped with a hollow channel ( not shown ) through which a sparking wire can be passed to enable the legs 14 ( if formed of a conductive material ) to be energized with electrosurgical cutting or coagulating current . the embodiment of fig1 through 4 shows the ends 28 of the legs 14 as being connected together , so that the legs 14 in combination form a basket 20 . in fig1 through 4 , the ends 28 of the legs 14 and the distal portion 16 of the cable 18 are interconnected with a distal connector 30 which , depending on the materials used to form the legs 14 and cable 18 , can be attached by metallurgical joining ( e . g ., soldering , brazing , etc .) or with a mechanical crimp joint . while the device 10 is shown as being equipped with four legs 14 , it is foreseeable that fewer or greater numbers of legs could be employed . for example , the device could have two legs 14 ( forming , in effect , a snare ) or as many as eight legs 14 or more . as represented in fig1 , the legs 14 are formed to have a parabolic curved shape , as by such known methods as stamping , rolling , extruding , etc . the legs 14 are formed from a sufficiently rigid material , such as a stainless steel , or a “ shape memory ” nickel - titanium alloy such as nitinol , so that the parabolic curved shape of the legs 14 causes the midportions of the legs 14 to automatically deploy radially outward and away from each other ( and away from the distal portion 16 of the cable 18 ) when the legs 14 are deployed outside the sheath 12 with the cable 18 . as a result , the device 10 does not require a plunger capable of being actuated relative to the legs 14 in order to force the legs 14 radially apart to form the basket 20 of fig1 . the legs 14 are sufficiently elastically deformable so that , when the sheath 12 is advanced over the legs 14 , the legs 14 elastically collapse radially toward each other to acquire an intermediate position ( fig3 ) in which the basket 20 is partially collapsed . with further advancement of the sheath 12 ( fig4 ), the legs 14 are largely stowed within the sheath 12 and substantially parallel to each other and to the distal portion 16 of the cable 18 . a key feature of the present invention is that each leg 14 has a concave - convex cross - section that contributes greater strength to the legs 14 , such that the legs 14 maintain their form and alignment and provide greater grasping strength and expansion force than extraction devices equipped with wires having other cross - sectional shapes . as a result , the device 10 is well suited for moving , manipulating and extracting biological material , such as calculi , stones , etc . as depicted in fig5 , the legs 14 have a concave - convex cross - section in the sense that the inward surfaces 22 of the legs 14 facing each other are concave , while the oppositely - disposed outward surfaces 24 of the legs 14 are convex . each surface 22 and 24 is represented in fig5 as having a substantially constant radius of curvature , with the result that thicknesses of the legs 14 in the direction of a radial of the curvature are substantially constant . the sides 26 of the legs 14 are contiguous with the surfaces 22 and 24 , and can be of any suitable shape , e . g ., rounded , flat such as the radials of the curvatures of the surfaces 22 and 24 , etc . when fully collapsed , the legs 14 define a tubular shape in the sense that the legs 14 in combination define a circular exterior cross - section and a circular opening that is sized to accommodate the cable 18 . as such , and also as evident from fig4 , the sides 26 of the legs 14 contact each other when the legs 14 are fully collapsed within the sheath 12 . this aspect of the invention , in which gaps between adjacent legs 14 are eliminated as the sheath 12 advances over the legs 14 , enables the device 10 to define a circumferentially continuous enclosure capable of fully containing small renal and ureteral calculi and other very small biological material . this aspect of the invention also enables the device 10 to be used to remove polyps or growths for biopsy by placing the basket 20 so that the polyp / growth is between a pair of adjacent legs 14 , after which the basket 20 is completely collapsed with the sheath 12 such that the sides of the legs 14 have a scissor effect on the polyp / growth . fig6 shows a second embodiment of an extraction device 110 of this invention , in which the legs 14 have a longitudinal configuration that causes the basket 120 to have a helical shape . other than the helical shape of the basket 120 , the device 110 can have an identical construction to the device 10 of fig1 through 4 . when used to remove a stone ( or calculi or other object ) from a cavity of the human body , the legs 14 are extended from the sheath 12 with the cable 18 such that the legs 14 resiliently expand outward to reacquire their parabolic curved shape . once the stone is surrounded by the legs 14 so as to be nested with the basket 20 , the cable 18 is actuated relative to the sheath 12 to advance the sheath 12 over the legs 14 , causing the basket 20 to collapse and grasp the stone . by subsequently extending the legs 14 from the sheath 12 , the stone can be released . as such , surgically moving , manipulating and extracting bodies and materials within the human body is performed without additionally operating a plunger or other extraneous component to expand and contract the basket 20 formed by the legs 14 . as noted above , the legs 14 can be formed by such known methods as stamping , rolling , extruding , etc . rolling and stamping are particularly desirable from the standpoint of being able to produce legs 14 that are dense and therefore capable of generating greater strength and expansion force . fig7 depicts a multistage stamping or rolling process suitable for producing the legs 14 for the devices of fig1 through 6 , as well as subsequent embodiments of the invention described in reference to fig9 through 12 . in fig7 , a solid round wire 32 is shown supported on a die ( or bottom roller ) 34 , and then engaged with a ram ( or upper roller ) 36 during multiple operations until a leg 14 is produced . legs 14 produced in this manner can be continuous and spooled in coils for later cutting to length and assembly with the cable 18 . as a result of being formed from round solid wire 32 , the lateral sides 26 of the leg 14 are not as flat as those of the leg 14 depicted in fig5 , and the edges defined at the intersections of the lateral sides 26 with the concave inward surface 22 and the convex outward surface 24 of the leg 14 are rounded and not sharp . furthermore , the inward and outward surfaces 22 and 24 are not necessarily equidistant from each other , resulting in the leg 14 having a nonuniform radial thickness . for example , the leg 14 in fig7 can be seen to be thinner near its sides 26 than at its center . as previously described in reference to the embodiment of fig1 through 4 , when fully collapsed the legs 14 define a tubular shape in the sense that the legs 14 in combination define a circular exterior cross - section and a circular opening , which is a result of their lateral sides 26 contacting each other along their entire lengths . the tubular shape defined by the legs 14 is depicted in fig8 , which evidences that gaps between adjacent legs 14 are eliminated so that the legs 14 define a circumferentially continuous enclosure capable of fully containing very small biological material . this aspect of the invention also maximizes the grasping strength of the legs 14 when attempting to capture an object . fig9 and 10 represent an extraction device 210 with legs 14 shaped as a result of being produced by the process depicted in fig7 . as with the previous embodiments , the legs 14 are adapted for being stowed within a sheath 12 , where the legs 14 assume a fully - collapsed position consistent with fig4 . as before , the legs 14 may be actuated with a cable ( not shown ) or other suitable actuating member capable of simultaneously retracting the legs 14 into the sheath 12 and deploying the legs 14 from the sheath 12 . in the embodiment of fig9 and 10 , the proximal ends of the legs 14 are connected together with a proximal connector 240 while the distal ends 28 of the legs 14 are connected together with a distal connector 230 so that the legs 14 in combination form a basket 220 when deployed . fig1 is illustrated with a portion of the sheath 12 removed to expose the collapsed legs 14 within the sheath 12 and evidence contact between the lateral sides 26 of the legs 14 . as evident from fig9 and 10 , the ability to fully collapse the legs 14 until their sides 26 touch enables the device 210 to fully contain small renal and ureteral calculi . this aspect of the invention also enables the device 210 to be used to remove polyps or growths for biopsy by placing the basket 220 so that the polyp / growth is between a pair of adjacent legs 14 , after which the basket 220 is completely collapsed with the sheath 12 such that the sides 26 of the legs 14 have a scissor effect on the polyp / growth . though not depicted in fig9 and 10 , the device 210 could be configured with the cable 18 of fig1 through 4 extending from the sheath 12 alongside the legs 14 , with the distal ends 28 of the legs 14 attached to the distal end 16 of the cable 18 with the distal connector 230 or other suitable means , as discussed in reference to the embodiment of fig1 and 4 . an extraction device 310 represented in fig1 and 12 is essentially identical to that of fig9 and 10 , with the exception that a distal connector is not employed such that the device 310 operates as forceps 320 . as in the embodiment of fig9 and 10 , the proximal ends of the legs 14 are connected together with a proximal connector 340 , and a portion of the sheath 12 is removed in fig1 to illustrate the collapsed legs 14 within the sheath 12 . also consistent with the previous embodiments of this invention , the ability of the device 310 to fully collapse the legs 14 until their sides 26 touch enables the device 210 to fully contain small renal and ureteral calculi , as well as have a scissor effect to remove polyps and other growths . the embodiment of fig1 and 12 provides the additional capability of grasping biological materials with the distal ends 28 of the legs 14 , which together define and operate as jaws capable of extracting materials embedded in a cavity wall . the terminal surfaces of the distal ends 28 can be angled outward in the distal direction so that embedded materials , such as a stone embedded in the wall of the calyces in a kidney , can be more readily extracted . while the invention has been described in terms of a preferred embodiment , it is apparent that other forms could be adopted by one skilled in the art . for example , appropriate materials could be substituted for those noted . accordingly , the scope of the invention is to be limited only by the following claims .
a surgical device having a sheath and legs slidably received within the sheath . the legs are adapted to move outwardly away from each other when deployed from the sheath to establish a deployed position , and to move inwardly toward each other to collapse within the sheath and define a stowed or grasping position . each of the legs has a transverse cross - sectional shape defined by a concave surface , an oppositely - disposed convex surface , and lateral sides interconnecting the concave and convex surfaces . the legs and sheath are configured to cause the legs to fully collapse within the sheath such that the lateral sides of adjacent pairs of the legs contact each other , and / or the legs define a tubular shape having a circular opening defined by the convex surfaces of the legs and a circular exterior cross - section defined by the concave surfaces of the legs .