Power-assisted arthroscopic surgical device with suction tube

Abstract: A rotatable surgical shaver handpiece having a rotating elongated inner member within a fixed outer member is provided with a means for varying the cutting window orientation of the outer tubular member. The window orientation is adjusted by providing a rotatable collet assembly which has a hollow, outer, longitudinally movable body to which the outer hub member is keyed. The outer collet member is concentrically situated about an inner collet body and is fixed to an annular, toothed locking surface which is movably biased against an identical toothed locking surface fixed to the inner collet body. The teeth have sloped sides and are shallow such that the pre-loaded force compressing the two locking surfaces together is easily overcome by rotating the outer collet body to cause the teeth of one locking surface to slide along the teeth of the mating locking surface. In another embodiment, the invention is provided with a blade recognition means for identifying a code associated with a particular blade assembly regardless of the window orientation of the outer tubular member of the blade assembly. In another embodiment of the invention the handpiece is provided with an extruded body fitted with a longitudinally slidable aspiration control switch.

Description: BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a surgical instrument, suitable for example for use during endoscopic surgical procedures for driving an elongated rotatable surgical tool and aspirating material from the surgical work site. The invention also relates to the combination of such a surgical instrument with an elongated surgical tool. Description of the Prior Art Surgical handpieces have long been used to house the mechanical and electrical components necessary to operate a variety of powered surgical instruments attached to the handpiece. While some such instruments are used in open surgical procedures, the use of surgical cutting instruments has also become well accepted in performing closed surgery such as arthroscopic or more generally endoscopic surgery. The terms "arthroscopic" and "endoscopic" may be used interchangeably herein and are intended to encompass arthroscopic, endoscopic, laparoscopic, hysteroscopic or any other similar surgical procedures performed with elongated instruments inserted through small openings in the body. In such surgery, access to the surgical site is gained by one or more portals and instruments used in the surgical procedure must be elongated to permit the distal ends of the instruments to reach the surgical site. Surgical cutting instruments for use in closed surgery are commonly referred to as "shavers" or "blades" and comprise an assembly composed of a rotatable inner member situated within a non-rotatable outer member. Such shavers conventionally have an elongated outer tubular member terminating at a distal end having an opening in the side and/or end wall to form a cutting port or window. An elongated inner tubular member is concentrically disposed in the outer tubular member and has a distal end disposed adjacent the opening in the distal end of the outer tubular member. The distal end of the inner tubular member has a surface or edge for engaging tissue via the opening in the distal end of the outer tubular member and in many cases cooperates with the opening to shear or cut tissue. The inner and outer tubular members both have hubs at their proximal ends to enable the shaver blade assembly to be attached to a handpiece to facilitate manipulation of the shaver blade as well as to provide power to the inner tubular member so it can be rotatably driven at its proximal end. The drive mechanism is normally a small electric motor situated in the handpiece and controlled by a foot switch, a finger actuated switch on the handpiece or switches on a console supplying power to the handpiece. The distal end of the inner tubular member can have various configurations depending upon the surgical procedure to be performed and the opening of the distal end of the outer tubular member has a configuration to cooperate with the particular configuration of the distal end of the inner tubular member. Cut tissue and irrigating fluid are aspirated through the hollow lumen of the inner tubular member to be collected via a tube communicating with the handpiece. In such instruments, the cutting window at the distal end of the outer member is often fixed at a given angular orientation relative to the handpiece. The hub at the proximal end of the outer member is keyed to fit in a receiving collet having a keyway facing in only a particular orientation which necessarily causes the cutting window to face in a predetermined direction. The choice of where to position the keyway relative to other features on the handpiece is made during manufacture. However, in certain surgical procedures the surgeon may prefer to have the cutting window face in different directions relative to the handpiece, particularly if the handpiece has control switches or is shaped in a way which interferes with its use in certain window orientations. While some mechanisms are known by which the angular orientation of the cutting window is adjustable, such mechanisms are often cumbersome and are difficult to operate during the course of an endoscopic surgical procedure. One known cutting window orientation adjustment method involves simply providing multiple keyways (or bayonet locking mechanisms), removing the shaver blade and reinserting the hub into the collet in a different position. Another known method utilizes a single keyway to fix the window relative to the collet and means to enable the collet itself to be unlocked and turned without removing the blade. This method, utilized for example on a APS High Speed Arthrotome manufactured by Hall Surgical, Carpinteria, California, requires a procedure in which the handpiece body and collet are each held, moving the collet distally a certain distance relative to the body, turning the collet to orient the window as desired and then releasing the collet to lock it in place relative to the body. While not necessarily detrimental in an open surgical procedure, this type of adjustment may in some instances be awkward to perform during the course of an arthroscopic procedure. An easier window orienting mechanism would be desirable. While the ability to select the cutting window orientation is desirable, doing so with existing shaver blades destroys the blade recognition feature utilized in many arthroscopic shaver systems. This feature relies on encoding the blades with discrete magnets embedded in the hub of the outer tubular member and reading the position of these magnets with sensors in the handpiece. This information is used to control the speed of the drive motor and to perform other identification functions understood by those skilled in the art. Rotating the outer tubular member in order to orient the cutting window moves the magnets in the hub away from the sensors, thus providing inaccurate information to the control system operating the handpiece. It would be desirable to have the ability to orient the cutting window of a shaver blade without compromising the ability of the control system to read the code associated with the blade in use. It is an object of this invention to produce a surgical shaver handpiece in which the orientation of the cutting window of the outer member is easily adjustable without disengaging the blade from the handpiece. It is another object of this invention to produce a surgical shaver handpiece in which the orientation of the cutting window may be changed while retaining the ability of the control system to read the code associated with the blade in use in any window orientation. SUMMARY OF THE INVENTION These and other objects of this invention are achieved by the preferred embodiment disclosed herein which is a surgical instrument for driving an elongated surgical tool. The instrument comprises a housing with a drive means within the housing. A releasable collet means at the distal end of the housing receives the surgical tool and holds it longitudinally fixed relative to the drive means. The instrument is characterised by a detent means to retain the collet in a selected position, the detent means being manually rotatable without being first manually urged longitudinally. The detent means further comprises a first locking plate having a first locking surface facing in a distal direction and a second locking plate having a second locking surface facing in a proximal direction. The first and second locking surfaces engage each other to prevent relative rotation between the first and second locking plates. A hollow, outer cylindrical collet member is fixedly secured to the first locking plate. A spring means is interposed between the outer collet member and the second locking plate for selectively maintaining the first and second locking surfaces in engagement. The invention also provides the combination of a surgical instrument and an elongated surgical tool having a rotatable inner member rotatably situated within an outer member, the outer member having a cutting window facing at least partially in a direction transverse to the axis. The instrument comprises a housing with a drive means within the housing for driving the inner member of the tool. A releasable collet means receives the surgical tool and holds it longitudinally fixed relative to the drive means. The collet means receives the outer member of the tool in a predetermined angular orientation relative to the axis of the housing. A rotation enabling means is provided for enabling rotation of the collet means for varying the predetermined angular orientation. The instrument is characterised in that the rotation enabling means comprises detent means to retain the collet in a selected position, the detent means being manually rotatable without being first manually urged longitudinally. The detent means further comprises a first locking plate comprising a first locking surface facing in a distal direction and a second locking plate comprising a second locking surface facing in a proximal direction. The first and second locking surfaces engage each other to prevent relative rotation between the first and second locking plates. A hollow cylindrical collet member is fixedly secured to the first locking plate and has a keyway means for fixing the position of the outer member. A spring means is interposed between the collet member and the second locking plate for selectively maintaining the first and second locking surfaces in engagement. In a preferred embodiment the handpiece has a longitudinally aligned first bore extending between the proximal end and the distal end for containing a motor for driving a surgical instrument and a longitudinally aligned second bore, parallel to the first bore, for providing an aspiration conduit for aspirating material from the distal end to the proximal end. A method of manufacturing the hand piece comprises the steps of providing an extrudable material, extruding the extrudable material with the first and second bores extending through the body and forming an oblique aspiration channel extending from said second bore distally to said first bore. The method further comprises providing a longitudinally movable aspiration control valve having an elongated pin sized to be axially received in the distal end of the second bore and sufficiently elongated to selectively occlude the oblique aspiration channel. A slide body is adapted to slidably retain the pin within the second bore and to seal the distal end of the second bore. In another preferred embodiment, the instrument comprises a housing having a drive means for driving the tool and a releasable collet means for receiving the tool and holding it fixed to the drive means. The collet means is adapted to receive the tool in a predetermined angular orientation relative to the housing. The instrument has a means for enabling rotation of the tool to vary the predetermined angular orientation and a recognition means for identifying the tool regardless of its angular orientation relative to the housing. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side elevation view of a surgical shaver handpiece constructed in accordance with the principles of this invention. Figure 2 is a top view of Figure 1 showing the slide aspiration control valve in a fully closed, proximal-most position. Figure 3 is a top view of Figure 1 showing the slide aspiration control switch in a fully open, distal-most position. Figure 4 is an exploded partially cross-sectional view of Figure 1. Figure 5 is an assembled partially cross-sectional elevation view of Figure 1. Figure 6 is a cross-sectional view of Figure 4 taken along the lines 6-6. Figures 7a, 7b and 7c are side elevation views of the collet subassembly shown in Figure 4 in various stages of assembly. Figure 8 is a cross-sectional view of Figure 7b taken along the line 8-8. Figure 9 is a cross-sectional view of Figure 7c taken along the line 9-9. Figure 10 is a cross-sectional view of Figure 4 taken along the line 10-10. Figure 11 is a cross-sectional elevation view of a portion of the collet subassembly of Figure 7c. Figure 12 is a right end view of Figure 11. Figures 13a and 13b are side and front elevation views, respectively, of a locking ring component shown in Figure 7a. Figure 14 is an exploded side elevation view, partially in cross-section, of a shaver blade for use with the handpiece of Figure 1. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to Figures 1 through 5 there is shown a surgical shaver handpiece 10 constructed in accordance with the principles of this invention. Handpiece 10, constructed in a modular fashion to facilitate its assembly and repair, comprises a body 12 having a distal end 14, a proximal end 16, a collet assembly 18, a motor/seal assembly 20 and a cable assembly 22. As best seen in Figures 5 and 6, body 12 has two parallel, longitudinally extending throughbores: bore 24 is the main channel for receiving the motor/seal assembly 20 and collet assembly 18 and bore 26 is an aspirating channel which is provided with a slidable suction control valve 28 at the distal end 14 of body 12 and a tubing adapter 30 at the proximal end 16. An oblique aspiration communication channel 27 extends distally from bore 26 to bore 24. As best seen in Figure 6, body 12 has a tear-drop shape which, in the preferred embodiment, is formed by extruding an extrudable material (aluminum, plastic, etc.) with throughbores 24 and 26. Oblique channel 27 and the annular grooves, threads and internal component receiving channels must be machined into body 12 after the extrusion step, but these are relatively minor manufacturing steps which are also employed in prior art non-extruded units. All known prior art handpieces are more expensive and time consuming to produce because they are machined entirely from a single bar of material. An additional advantage to extrusion is that, as will be understood below, it facilitates the use of a simplified slide aspiration control valve 28. The rotatable self-locking collet mechanism in handpiece 10 comprises collet assembly 18 which is shown in more detail in Figures 7a, b and c. As will be understood below, collet assembly 18 serves to secure handpiece 10 to a shaver blade assembly. Collet inner body 100 is formed from an integral, hollow piece of material having a distal cylindrical portion 102, an intermediate cylindrical portion 104, a shoulder 106 and a proximal threaded portion 108. Cylindrical portion 102 is provided with three ball detents 110 equally spaced around the periphery of cylindrical portion 102 (only one ball detent is shown in Figure 7a). Cylindrical portion 104 is provided with three pin receiving apertures 112 (only one of which is shown) squally spaced around the periphery of cylindrical portion 104, the purpose of which will be explained below. Shoulder 106 is sized to smoothly abut collet body 100 against the distal opening 14 of handpiece body 12. Cylindrical threaded portion 108 is received in distal end 14 and secures the mounting of collet assembly 18 to handpiece body 12. Locking plate 120, best seen in Figures 7 and 13, is an annular ring having three equally spaced pin receiving apertures 122, a smooth proximally facing rear surface 124 and a toothed distally facing front surface 126. Locking ring 120 has an internal aperture 128 having a diameter sufficient to enable it to slide along intermediate cylindrical portion 104. An identical locking ring 130 is provided with three pin receiving apertures 132, a distally facing rear surface 134 and a proximally facing front surface 136. The central aperture of locking ring 130 is also sized to be received on intermediate portion 104 although locking ring 130 is fixed to portion 104 by pins 113 inserted through pin apertures 132 and into apertures 112, as best seen in Figure 8. As shown in Figure 7b, once locking rings 120 and 130 are assembled onto collet body 100, a cylindrical pre-loading spring 140, sized to be received on cylindrical portion 102, is abutted against the distally facing rear surface of locking ring 130 and ball retaining ring 142 is then abutted against the distally facing side of spring 140. Balls 144 are then inserted into ball detents 110 as shown in Figures 7c and 9 and the entire assembly is held together by hollow, cylindrical outer collet body member 150 which is pinned via pin 153 to three equally spaced pin receiving apertures 152 to corresponding apertures 122 in locking ring 120, as best seen in Figure 10. Pre-loading spring 140 serves to cam balls 144 into the locked position and also to urge locking plate 120 against locking plate 130 (note they are spaced in Figure 7c for clarity). Thus, it will be understood that while outer collet body 150 is normally biased distally by spring 140, thereby causing the toothed surfaces of locking rings 120 and 130 to engage, collet body 150 may be caused to move rearwardly (proximally) in the direction of arrow A by mere rotation. The mechanical advantage of the locking rings allows direct turning of the outer collet body without pulling it proximally or pushing it distally. It will be understood that turning the collet body 150 causes the facing front surfaces of the locking rings to disengage, thereby enabling relative rotation of the locking rings. Outer collet body 150, best seen in Figures 11 and 12, has a hollow interior 154 and an internal shoulder 156 which engages the distal side of ball retainer 142. A distal axially aligned aperture 158 is sized to receive a shaver blade assembly and is provided with a keyway 160 adapted to engage a corresponding key 192 on a shaver blade 172 best seen in Figure 14. Referring briefly to Figure 14, shaver blade assembly 172 comprises an elongated inner blade 174 and an elongated outer blade 176. Inner blade 174 comprises an elongated tubular member 178 having a cutter 180 at its distal end and a hub 182 at its proximal end. Hub 182 includes a drive tang 184 to engage drive connection 185 of motor/seal assembly 20 (best seen in Figure 5) to drive the inner member. Outer blade 176 comprises an elongated tubular member 186 having a cutting window 188 at its distal end and a hub 190 at its proximal end. Hub 190 includes a key tang 192 which fits into the keyway of the outer collet body member. Referring to Figures 13a and 13b, a detailed view of locking ring 120 shows that it has a central aperture 128 and a plurality of annularly arranged shallow teeth 125. The sides 126, 127 of adjacent teeth are separated by angle A which in the preferred embodiment is on the order of 119°. The shallow design of the teeth enables the locking rings to be easily rotated relative to one another without first having to push outer collet body longitudinally rearwardly to disengage the teeth. The teeth of one locking ring slide along the teeth of the other locking ring merely by manually rotating the outer collet body. The annular array of 24 teeth enables the collet to be adjustable throughout 360° in increments of 15°.

Claims: A surgical instrument (10) for driving an elongated surgical tool (172), said instrument comprising: a housing (12); a drive means (20) within said housing (12); a releasable collet means (18) for receiving the surgical tool (172) and holding it longitudinally fixed relative to said drive means (20); characterised in that the collet means comprises detent means to retain said collet in a selected position, said detent means being manually rotatable without being first manually urged longitudinally, said detent means further comprising: a first locking plate (120) comprising a first locking surface (125) facing in a distal direction; a second locking plate (130) comprising a second locking surface (136) facing in a proximal direction, said first and second locking surfaces (125, 136) adapted to engage each other to prevent relative rotation between said first and second locking plates (120, 130); a hollow cylindrical collet member (150) fixedly secured to said first locking plate (120); and spring means (140) interposed between said collet member (150) and said second locking plate (130) for selectively maintaining said first and second locking surfaces (125, 136) in engagement. A surgical instrument according to claim 1 wherein said first and second locking surfaces (125, 136) are annular and comprise a plurality of annularly arranged teeth (125) comprising a plurality of crests spaced by a plurality of troughs, the teeth (125) of said first locking surface (125) adapted to nest against the teeth (125) of said second locking surface (136). A surgical instrument according to claim 1 wherein adjacent ones of said teeth (125) have sides converging at approximately 120°. The combination of an elongated surgical tool (172) having a rotatable inner member (174) rotatably situated within an outer member (176), said outer member having a cutting window (188) facing at least partially in a direction transverse to the axis, and a surgical instrument (10) comprising: a housing (12); a drive means (20) within said housing (12) for driving the inner member of the tool; a releasable collet means (18) receiving the surgical tool (172) and holding it longitudinally fixed relative to said drive means (20), said collet means (18) receiving said outer member (176) of said tool (172) in a predetermined angular orientation relative to the axis of said housing (12); and means for enabling rotation of said collet means (18) for varying said predetermined angular orientation, characterised in that said means for enabling rotation comprises detent means to retain said collet in a selected position, said detent means being manually rotatable without being first manually urged longitudinally, said detent means further comprising: a first locking plate (120) comprising a first locking surface (125) facing in a distal direction; a second locking plate (130) comprising a second locking surface (136) facing in a proximal direction, said first and second locking surface (125, 136) engaging each other to prevent relative rotation between said first and second locking plates (120, 130); a hollow cylindrical collet member (150) fixedly secured to said first locking plate (120) and having a keyway means (160) for fixing the position of said outer member (176); and spring means (140) interposed between said collet member (150) and said second locking plate (130) for selectively maintaining said first and second locking surfaces (125, 136) in engagement.

Inventors: BERMAN PHILLIP J, GLOWA MICHAEL P, SLENKER DALE, BERMAN, PHILLIP J., GLOWA, MICHAEL P., SLENKER, DALE
Applicants: LINVATEC CORP, LINVATEC CORPORATION
Application year: 1995
Main classification: A61B17
IPC codes: A61B17, A61M1