FASCIA CUTTER WITH CAUTERIZING CAPABILITY

Abstract: A fascia cutter (10) comprises a shaft (12) having a transverse slot (18) at its distal end (14). The blade (20) is reciprocatably mounted within the shaft (12) so that it may be axially advanced within the slot (18). A rod (24) for manually reciprocating the blade (20) is provided on the proximal end (16) of the shaft. The fascia cutter (10) is useful for enlarging previously formed abdominal penetrations where the shaft (12) is inserted in the penetration, the slot (18) is engaged about the edge of the fascia, and a radial incision is made in the fascia.

Description: FASCIA CUTTER WITH CAUTERIZING CAPABILITY BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to the structure and use of surgical instruments, and more particularly, to a device and method for enlarging abdominal penetrations by the controlled cutting of the fascia transversalis. Least invasive surgical (LIS) techniques, such as laparoscopic, endoscopic, and arthroscopic surgery, are generally performed through small incisions using specialized instruments to perform desired surgical procedures. Usually the instruments are introduced through a tube, such as a cannula, while the physician observes manipulation of the instruments through specialized imaging equipment, such as a laparoscopes, endoscopes, and arthroscopes. Such LIS techniques offer significant advantages over conventional "open" surgical procedures. In particular, the LIS techniques are usually less traumatic, require a shorter recovery time, and are less costly than the corresponding conventional surgical techniques. Of particular interest to the present invention are laparoscopic cholecystectomy procedures where the gallbladder is surgically severed and withdrawn through a small cannula, typically having a diameter of about 10 mm. While such procedures have been very successful and have become increasingly common, complications sometimes arise when the gallbladder is enlarged or contains gallstones which are too large to be withdrawn through the cannula. In such cases, it is frequently necessary to remove the cannula and to enlarge the abdominal penetration, typically by making one or more incisions at the penetration using a scalpel or other conventional cutting blade. The ability to surgically enlarge the penetration, however is problematic. The surgeon must hold onto the gallbladder, and great care must be taken to avoid losing the gallbladder, cutting the gallbladder with the scalpel, or otherwise causing the gallbladder to spill its contents within the abdomen. Loss of the contents of the gallbladder into the abdomen is problematic, often causing bile septicemia. Enlargement of the abdominal penetration is made particularly difficult by the presence of the primary fascial layer, referred to as the fascia transversalis, which is a sheet of tough, fibrous material that envelops the body beneath the skin. It is the fascia transversalis which provides the primary barrier or resistance when making any abdominal incision or penetration. While the resistance is not a particular problem when an initial penetration is made using a needle, trocar, or other instrument, enlargement of an initial hole is problematic. The fascia transversalis lies beneath the skin, a superficial fascial layer, and the rectus muscle, thus making access quite limited. Moreover, it is desirable to enlarge the penetration as little as possible in order to minimize further trauma to the patient. This can be difficult, however, using a conventional surgical scalpel without visual access (as the laparoscope has already been removed and would be unable to visualize the fascia transversalis if in place) . For these reasons, it would be desirable to provide improved devices and methods for enlarging abdominal penetrations, particularly for enlarging very small holes on the order of 5-12 mm through the fascia transversalis. Such devices and methods should permit easy location of the fascial layer, even when the layer cannot be seen by the surgeon. The devices and methods should further provide for controlled cutting so that the penetration can be enlarged by a known amount as well as for operation by a single hand so that the surgeon can manipulate other surgical instruments simultaneously. 2. Description of the Background Art U. S. Patent No. 3,815,604 describes a device for intraocular surgery comprising an outer tube having an aperture and an inner tubular blade which can be advanced to sever material penetrating the aperture. U. S. Patent Nos. 1,978,495; 1,881,250; 1,798,902; and 1,683,708, describe electrosurgical instruments comprising a blade which reciprocates in an enclosed ring. The instruments are intended for removing tonsils, where the tonsils are captured by the ring, and the blade advanced within the ring to sever the tonsils. U. S. Patent No. 749,689 describes a surgical instrument with an actuable blade. U. S. Patent Nos. 1,741,461 and 1,731,069 describe surgical instruments having actuable components at their distal ends. SUMMARY OF THE INVENTION The present invention comprises a novel device and method for cutting and enlarging fascial penetrations during surgical procedures, such as laparoscopic cholecystectomy. The device and method permit the surgeon to locate the fascial layer "by feel" as the device is introduced through a previously formed narrow diameter abdominal penetration. Once the fascial layer has been located, the device can be readily positioned to make a first cut. The first cut can be lengthened by making successive cuts in the same direction. Alternatively, a series of radially spaced-apart incisions can be formed about the periphery of the hole through the fascial layer. In this way, the fascial penetration, which is the primary barrier to intra- abdominal access, can be enlarged with minimum risk of injury to surrounding tissues and structures. The device of the present invention comprises an elongate shaft having a U-shaped transversely oriented slot at its distal end. A blade having a generally transverse cutting edge is mounted to axially reciprocate within the slot, and a means for manually reciprocating the blade is provided at the proximal end of the shaft. An electrical connector is optionally provided to permit connection of the cutting blade to conventional electrosurgical power supply, allowing the surgeon to optionally perform cauterization following (or simultaneously with) each incision. The nature of the reciprocating means is not critical, but the reciprocating means will usually comprise a conventional three-ring actuator, lever grip, or the like. The dimensions of the device are preferably selected to permit controlled cutting of the fascial penetration, where the initial abdominal penetration was made to receive a 5 mm or 10 mm cannula. Preferably, the width of the shaft (along the distal end which will be inserted into the abdominal penetration) will be 10 mm or less, preferably being 7 mm or less, and more preferably being about 5 mm or less, at least over the distal 5 cm of its length. The length of the slot in the axial direction will be sufficient to receive the thickness of the fascial layer, typically being in the range from about 3 mm to 5 mm. The depth of the transverse slot will be selected to provide a. desired depth of cut, typically being in the range from 2 mm to 6 mm. In the method of the present invention, the shaft is inserted into a previously formed abdominal penetration until the surgeon can feel the distal tip of the shaft reach the fascial layer. The shaft is then manipulated so that the fascial layer is received within the slot, and the surgeon can then make a first incision by actuating the blade using the manual actuating means. Optionally, the incision is cauterized by applying current through the electrosurgical power supply. Usually, the surgeon will make a series of incremental cuts in a single direction from the preexisting hole, resulting in an enlarged penetration. In a preferred method, the enlarged penetration will be used to remove an enlarged gallbladder or a gallbladder containing oversized gallstones as part of a laparoscopic cholecystectomy procedure. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a fascial cutter device constructed in accordance with the principles of the present invention. Fig. 2 is a side elevational view of the fascial cutter of Fig. 1, shown in section. Fig. 3 illustrates an alternate blade configuration which could be employed with the fascial cutter of Fig. 1. Figs. 4 and 5 illustrate alternate blade actuating means comprising a lever grip handle. Figs. 6A-6C illustrate the method of the present invention for enlarging a penetration through the fascia transversalis in the abdomen. DESCRIPTION OF THE SPECIFIC EMBODIMENTS The fascia cutter of the present invention comprises an elongate shaft having proximal and distal ends and a U-shaped slot near its distal end. The blade, having a generally transverse cutting edge, is reciprocatably mounted within the shaft so that it can be axially translated through the slot. Usually, the blade will be axially advanced in the distal direction, but there is no reason why the design of the device could not be modified to permit the blade to be advanced in the proximal direction. A means for manually reciprocating the blade is provided at the proximal end of the shaft, and the device will be used by introducing the distal.end of the shaft through a previously formed abdominal penetration and engaging the slot about an edge of a fascial layer, usually the fascia transversalis. The blade can then be reciprocated to make one or more successive radial incisions in a single direction in the periphery of the previously formed hole through the fascial layer. The shaft of the fascia cutter will typically be tubular, but could have other cross-sectional geometries, such as rectangular, polygonal, irregular, or the like. The distal portion of the shaft, however, must have a maximal dimension (in any direction) which permits easy introduction of the shaft into the previously formed abdominal penetrations. Usually, the maximal dimension (i»e. , diameter in the case of tubular shafts) will be less than 10 mm, preferably being less than 7 mm, and most preferably being 5 mm or less. The narrow width of the shaft will usually be maintained along its entire length, but there is no reason why a proximal portion of the shaft cannot be enlarged. It is only necessary that the narrow dimension of the shaft be maintained over a distal length sufficient to permit introduction of the shaft to a desired depth, usually being at least 5 cm, preferably being at least 3 cm. The dimensions of the transverse slot are more critical. The slot should have a sufficient axial length to permit receiving of the fascial layer, typically being from 3 mm to 5 mm in axial length, although in some embodiments being 10 mm or longer in the axial direction. The depth of the slot will be selected to provide the desired depth of the cut when the blade is actuated, usually being from 1 mm to 6 mm, preferably being from 2 mm to 5 mm. The slot will be located at or near the distal tip of the shaft, preferably being within 5 mm of the distal tip, more preferably being within 2 mm of the distal tip. In some embodiments, however, the device may employ a more tapered blade which necessitates that the axial slot be moved proximally from the distal tip of the shaft (See Fig. 3 and the accompanying description hereinbelow) . The shaft will be substantially rigid, usually being formed from a metal or rigid plastic. Conveniently, the shaft may be formed from surgical stainless steel. The entire device will usually be disposable, but it will be possible to construct reuseable (sterilizable) devices having a replaceable 5 cutting blade. The blade will be similar to conventional surgical scalpel blades. It is possible, although not necessary, to construct the device to receive and utilize conventional scalpel blades. Preferably, the device will 10 employ a permanently mounted cutting blade, and the device will be disposed after a single use or procedure. The cutting edge of the cutting blade will be oriented transversely to the axis of the elongate shaft. By transverse, it is meant that the cutting edge of the 15 cutting blade will be able to cut through the fascial layer as the blade is axially advanced. In a preferred embodiment, the blade is oriented at an angle in the range from about 75° to 90° relative to the axis of the shaft. Such a blade orientation is utilized when the 20. shaft will have a blunt (non-tapered) end as illustrated in Figs. 1 and 2. Alternatively, the cutting edge of the blade can be tapered, as illustrated in Fig. 3, in which case the distal tip of the shaft will usually be tapered to accommodate the blade. Such tapered blades will 25 usually have a cutting edge which is oriented at 20° to 75° relative to the axis of the shaft. The remaining aspects of the device of the present invention will be described in connection with the figures which disclose and illustrate the exemplary 30 embodiments. Referring now to Figs. 1 and 2, the construction of a first exemplary fascia cutter 10 will be described. Fascia cutter 10 comprises an elongate shaft 12 having a distal end 14 and a proximal end 16. A 35 transversely oriented slot 18 is formed near the distal end 14 of the shaft 12. A cutting blade 20 slidably mounted within an axial lumen 22 of the shaft and connected to a rod assembly 24. The rod assembly 24, in turn, includes a reduced diameter region 26 which passes through a flange 30 formed in the lumen of the shaft 12. A spring 28 is received on the reduced diameter region 26 and abuts the flange 30 so that it is compressed as the rod assembly 24 is advanced distally, as described in more detail below. In this way, the blade 20 can be axially advanced by pressing on the end of the rod assembly 24 against the force provided by spring 28. Conveniently, a three-ring actuator is provided on the elongate shaft 12. Radially opposed side rings 40 and 42 are mounted on the shaft 12 itself, while the third ring 34 is secured to the proximal end of the rod assembly 34. In this way, the surgeon can hold the device in one hand with a pair of fingers inserted through rings 40 and 42 and a thumb inserted through ring 44. The surgeon can then manually actuate the blade 20 simply by manually depressing the third ring 44. As illustrated in Figs. 1 and 2, the distal end 14 of the shaft 12 is blunt (non-tapered) and the slot 18 is located very close to the distal tip. Such a blade and tip design is desirable since it permits the surgeon to locate the fascial layer with the tip, and only minor manipulation is necessary to engage the slot 18 through the previously formed hole in the fascial layer. An alternate tip and blade design is illustrated in Fig. 3. Blade 20• has a tapered cutting edge 50. Distal end 14' of the shaft must similarly be tapered in order to accommodate full advancement of the blade 20'. While the embodiment of Fig. 3 may be slightly more difficult to position than the embodiment of Figs. 1 and 2, the tapered nature of the blade 20' may enhance the cutting ability. An electrical connector 60 is attached to the proximal end of the rod assembly 24. The rod assembly 24 will be electrically conductive, or include a separate wire connector, so that a conductive path is provided between the connector 60 and the blade 20. Connector 60 extends outward through an elongate slot 62 in the shaft 12. In this way, the connector 60 can reciprocate back and forth within the slot 62 as the blade 20 is being advanced and retracted. The connector 60 is suitable for coupling the device 10 to a conventional electrosurgical power supply. Such power supplies are available from commercial suppliers, such as Valleylab, Inc. (a Pfizer Co.), Boulder, Colorado; Aspen Labs, Inc. (a Conmed Co.), Englewood, Colorado; and Birtcher Corp. , Irvine, California. The cutting blade 22 can thus be used for monopolar cauterization in a conventional manner. Referring now to Fig. 4 and 5, alternate means for actuating a cutting blade in a device according to the present invention will be described. Each of these figures illustrates a conventional type of lever grip actuator assembly. In Fig. 4, a fascia cutter 70 comprises a shaft 72 having an integral handle structure 74. A transverse slot 76 is formed near the distal end 78 of the shaft 72, and a blade 80 is mounted to reciprocate past the slot. Blade 80 is connected to a rod 84 which extends into a hollow cavity 86 formed in the handle 74. A lever 86 is pivotally mounted on pin 88 connected to a proximal end of rod 84 by pin 90. A spring 92 is mounted within the handle, so that the spring is compressed when the lever 86 is pulled into the handle 74 (i.e., when the blade 80 is advanced) . In this way, the blade 80 can be axially advanced in the distal direction and will return to its retracted position under the force of spring 92. The embodiment of Fig. 5 is similar in most respects to that of Fig. 4, with identical components being given the same reference numbers. The primary difference in the embodiment of Fig. 5 is that a spring 94 is connected between the proximal end of rod 84 and a fixed pin 96 within the handle 74. Thus, when the lever 86 is manually depressed by the surgeon, spring 94 will be extended. The spring 94 will thus be able to retract the blade 80 in a manner similar to spring 92 of the embodiment of Fig. 4. Numerous other specific configurations for actuating the blade within the fascia cutter of the present invention will be apparent to those skilled in the art. The method of the invention will now be described in connection with Fig. 6A-6C. Typically, a cannula 100 will have been previously placed through an abdominal penetration. The cannula extends through the skin S (dermis) , superficial fascia SF, rectus muscle RM, fascia transversalis FT, and the peritoneum P. The method of the present invention is intended to enlarge the penetration which has already been formed in the fascia transversalis FT. Commonly, the cannula 100 will have a diameter of about 10 mm, and it will be desired to enlarge the abdominal penetration (particularly the hole through the fascia transversalis) to a size in the range from about 12 mm to 20 mm. After withdrawing the cannula 100, the shaft 12 of the device 10 of the present invention is inserted through the skin S, superficial fascia SF, and rectus muscle RM, until the distal tip of the shaft engages the fascia transversalis FT. The fascia transversalis is much more resistant to penetration than the other layers, and the surgeon will be able to feel when the tip of the shaft initially encounters the fascia transversalis. At that point, shaft 12 will be in the position illustrated in Fig. 6B. The surgeon next manipulates the distal end of shaft 12 until the edge of the fascia transversalis FT is received into the transverse slot 18 of the shaft 12. The surgeon will be able to confirm that the fascia has been engaged by feeling resistance in both directions as the shaft is urged up and down within the penetration. Once the shaft 12 is in place, the blade 20 can be manually reciprocated by the surgeon so that an initial radial incision is formed in the periphery of the hole. The incision can then be lengthened by making a series of successive (incremental) cuts in generally the same direction as the initial cut. The shaft 12 may then be withdrawn and the enlarged penetration is available for a variety of procedures. In particular, the enlarged penetration may facilitate removal of relatively large body parts or organs, such as removal of the gallbladder. In variations on the above-described method, the shaft 12 of the device 10 may be introduced after the gallbladder has been partially withdrawn through an abdominal penetration, typically using forceps after the cannula has been removed. The shaft 12 may be introduced down alongside the gallbladder which has been partially withdrawn, frequently after removal of the gallbladder has proven difficult. In this way, the penetration through the fascial layer can be enlarged during the course of a laparoscopic cholecystectomy. Although the foregoing invention has been described in detail for purposes of clarity of understanding, it will be obvious that certain modifications may be practiced within the scope of the appended claims.

Claims: WHAT IS CLAIMED ISI 1. A fascia cutter comprising: an elongate shaft having proximal and distal ends and a U-shaped transversely oriented slot at its distal end; a blade having a generally transverse cutting edge mounted to axially reciprocate within the transversely oriented slot; means at the proximal end of the shaft for manually reciprocating the blade within the slot; and means for connecting the blade to a power supply. 2. A fascia cutter as in claim 1, wherein the means for manually reciprocating the blade comprises a three-ring actuator. 3. A fascia cutter as in claim l, wherein the means for manually reciprocating the blade comprises a lever grip assembly. 4. A fascia cutter comprising: an elongate shaft having proximal and distal ends, an axial lumen extending between said proximal and distal ends, and a U-shaped transversely oriented slot at its distal end, wherein the width of the shaft does not exceed 10 mm over the distal 5 cm of its length and the slot has a length in the range from about 3 to 5 mm and a depth in the range from about 2 to 6 mm; a blade having a generally transverse cutting edge mounted to axially reciprocate within the transversely oriented slot; an electrically conductive rod assembly having proximal and distal ends and being slidably received within the axial lumen of the elongate shaft, wherein the blade is attached to the distal end of the rod assembly; an electrical connector attached to the rod assembly and extending through an axially elongate aperture in the shaft, whereby the blade can be connected to a power supply; and means at the proximal end of the shaft for manually reciprocating the blade within the transversely oriented slot. 5. A fascia cutter as in claim 4, wherein the cutting edge of the blade is oriented at an angle in the range from 75° to 90° relative to the axial direction. 6. A fascia cutter as in claim 5, wherein the distal tip of the shaft is blunt and extends no further than 2 mm from the distal extremity of the transverse slot. 7. A fascia cutter as in claim 4, wherein the cutting edge of the blade is oriented at an angle in the range from 20° to 75° relative to the axial direction. 8. A fascia cutter as in claim 4, wherein the means for manually reciprocating the blade comprises a three-ring actuator. 9. A fascia cutter as in claim 4, wherein the means for manually reciprocating the blade comprises a lever grip assembly. 10. A method for controlled cutting of a fascial layer, said method comprising: inserting a shaft having a transversely oriented slot near its distal end into an abdominal penetration; positioning the shaft so that the distal end extends through a hole in the fascial layer and that an edge of the fascial layer is received in the slot; and advancing a blade axially within the slot so that a limited portion of the fascial layer is severed. 11. A method as in claim 10, further comprising applying an electrical current to the blade to effect cauterization. 12. A method as in claim 10, wherein the slot has a transverse depth in the range from about 3 mm to 5 mm so that the depth of cut into the fascial layer is limited. 13. A method as in claim 10, further comprising rotating the shaft so that a radially spaced portion of the fascial layer is received in the slot and advancing the blade to make an additional cut in the fascial layer and enlarge the hole. 14. A method as in claim 13, further comprising withdrawing a gallbladder through the enlarged hole.

Inventors: MIZES CRAIG B, NODA WAYNE A, MIZES, CRAIG, B., NODA, WAYNE, A.
Applicants: LAPAROMED CORP, LAPAROMED CORPORATION
Application year: 1992
Main classification: A61B17
IPC codes: A61B17, A61B18