Powering Instrument For Stapling Skin And Fascia

Abstract

A disposable staple cartridge housing a plurality of staples on a flexible belt and adapted to inject and form the staples, singly, into the disunited skin or fascia of a patient. Downwardly projecting flanges on a staple pusher act directly on the forwardmost staple positioned between a pair of adjacent teeth in the flexible belt and move the staple, the belt and its contents, with each stroke of the pusher. The forwardmost staple, when acted upon by the pusher, advances, rides out of the plane of the flexible belt and into the plane of the pusher and is ejected and bent around an anvil assembly. On the return stroke of the pusher, the downwardly projecting flanges flex out of the plane of the next successive staple, moving over that staple, and then take a position in readiness for the following stapling operation. The cartridge is provided with means for preventing the retraction of the staple housing belt during the rearward stroke of the pusher. In a second embodiment of the disposable cartridge, a plurality of staples are advanced as described above, but the number of disposable elements are reduced. With this embodiment, an inventive adaptor serves to associate the cartridge with a powering instrument. Also disclosed is a novel and simplified gas activated powering unit which develops a rectilinear thrust for advancing and forming staples. In one embodiment of the instrument, the nose is rotatable to facilitate alignment of the cartridge with the incision to be sutured.

Parent Case Text

REFERENCE TO PRIOR APPLICATIONS

This application is a continuation-in-part of my prior U.S. Patent Application Ser. No. 97,995, entitled Cartridge and Powering Instrument for Stapling Skin and Fascia, filed on Dec. 14, 1970, now U.S. Pat. No. 3,717,294, issued Feb. 20, 1973.

Description

BACKGROUND OF THE INVENTION

The basic principle of ejecting and forming surgical staples in the disunited skin or facia of a patient is disclosed in U.S. Pat. No. 3,643,851, issued Feb. 22, 1972, and assigned to the present assignee. In this patent and in U.S. Pat. No. 3,662,939, issued May 16, 1972, also assigned to the present assignee, the staples housed in their respective cartridges are driven by helical screws which are, in turn, rotated by a complex gearbox arrangement integral with the powering instrument.

More recently, in the development of the skin and fascia staper, as evidenced in U.S. Pat. No. 3,618,842, issued Nov. 9, 1972, and U.S. Pat. No. 3,638,847, issued Feb. 1, 1972, each assigned to the present assignee, cartridges have been designed which eliminate the requirement for the complex gearing once needed in the powering of the instrument. In these issued patents, the output shaft of the powering instrument need only have rectilinear thrust capabilities. The staples are advanced by means designed into the cartridges themselves. In the first of these patents, the advancing pusher, integral with the cartridge, rotates a pair of staple-driving screws by means of cams formed in the rear portions of the screws. In the second of these patents, the staples are driven forward by the interaction of pairs of opposing ratchet teeth integral with the cartridge.

As with the known cartridges, gas powering units have been the subject matter of several patent applications in the past few years. Gas powering units have been described in the first of the issued patents noted above and in several of the subsequent patents also noted above. Further, a gas powering unit is described in U.S. Pat. No. 3,613,507, issued Oct. 19, 1971, entitled POWER PACK UNIT, also assigned to the present assignee. These units, while having proven themselves in actual usage tend to be somewhat more complex than is necessary. And, while the hydraulic actions of these units have been adequate for the intended purposes, there are areas wherein improvement is possible.

While the art of ejecting and forming staples in the skin or fascia of a patient has come a long way since its inception, both instruments and cartridges still tend to be somewhat complex in the manufacture and in operation. Accordingly, the costs associated with known cartridges and instruments tend to be high.

It is toward the provision of a cartridge and a powering instrument which are simplified both in design and in manufacture, and hence are reduced in cost, that the present invention is directed.

SUMMARY OF THE INVENTION

The present invention relates to two embodiments of a novel cartridge for carrying a plurality of surgical staples and adapted to form these staples in the disunited skin or fascia of a patient. The second embodiment of the inventive cartridge does not mount directly on a powering instrument, and hence the present invention also relates to a novel adaptor for associating the cartridge with the instrument. Still further, the present invention relates to a novel and simplified powering instrument, activated by gas under pressure, and adapted to mate with each embodiment of the invention cartridge for providing the rectilinear thrust capabilities necessary to actuate the cartridges.

In the first embodiment of the inventive cartridge, a flexible toothed belt is moveably housed in a main body. Staples are guided and are advanced by association with spaced teeth pf the flexible belt. The cartridge is equipped with an anvil integral with the main body and a pusher which serves the functions of advancing the staples and singly ejecting and forming same. On the forward face of the pusher element, are a pair of downwardly projecting flanges extending into the plane of the staples. With each forward stroke of the pusher, the flanges engage the forwardmost staple and advance same along a guide track in the cartridge. With the initial movement of the forwardmost staple, the flexible belt is advanced in the cartridge, thereby advancing each staple associated with the belt. With the advanced movement of the pusher, the forwardmost staple engages a ramp assembly and rides out of the plane of the flexible belt and into the plane of the pusher. The continued forward motion of the pusher ejects the forward staple from the cartridge and forms same about the anvil assembly.

On the return stroke of the pusher, with the flexible belt restrained against rearward movement, the downwardly projecting flanges ride over the next successive staple and then drop into the plane of that staple, thereby readying the cartridge for another staple ejecting operation.

With the invention cartridge, the surgeon is always apprised of the fullness of the cartridge. The number of staples remaining in the cartridge may easily be ascertained by inspecting the clear plastic bottom thereof. As the flexible belt moves into the region of the cartridge bottom, with each staple ejection, the line of the belt passes a set of numbers. The alignment of the belt end with a number is indicative of the remaining staples.

In the second embodiment of the invention cartridge, the staples are housed in and guided by a flexible belt and are ejected and formed much in the same manner as described above. However the second embodiment of the cartridge is much smaller than the first, is less costly to produce, and hence results in a savings when one remembers that the cartridge is disposable. The second embodiment of the cartridge takes the form of a main body in which is positioned a moveable flexible belt loaded with staples. A small pusher element, the forward face of which is constructed as described above, is slidably mounted in the main body.

The second embodiment of the inventive cartridge is designed to mate with an adaptor unit which connects the cartridge to the powering instrument. The adaptor takes the form of an elongate body in which is slidably mounted an arm for connecting the drive shaft of the instrument to the pusher of the cartridge, and on which is provided an anvil assembly. It should be apparent, therefore that the adaptor mates with the second embodiment of the cartridge in such a manner that the cartridge has each of the elements and functions possessed by the first embodiment of the cartridge. The difference, however, is that with the second embodiment of the cartridge, only a small pusher unit, rather than the elongated unit of the first embodiment, is disposable. Further, there is no disposable anvil assembly in the second embodiment.

The inventive instrument takes the form of a substantially cylindrical body housing a trigger unit, a gas supply chamber, a power pack unit and an output shaft. The instrument is designed to mate either with the first embodiment of the inventive cartridge or with the adaptor unit.

The power pack unit, or the portion of the inventive instrument which converts gas pressure into rectilinear motion, is similar, in many respects, to the power pack of U.S. Pat. No. 3,613,507 issued Oct. 19, 1971, noted above. Gas pressure originates in a standard CO.sub.2 tank and is maintained in the tank until the instrument is triggered. At that time, a spring biased gas seal is unseated, thereby allowing gas to flow into a first pressure chamber. Then the gas flows into a large pressure chamber and ultimately drives a piston integral with the output shaft of the instrument. Once the piston is driven, the gas seal is reseated by the action of the biasing spring, and the power pack unit is readied for the next driving operation.

Basically, the inventive powering unit differs from each of the units known to the prior art in that the prior art units require pressure differentials to reseat the gas seal. As a consequence of this, when the pressure in the CO.sub.2 tank changes from one firing to the next, so too does the required pressure for closing the gas seal. Therefore, the known gas powering units, while reliable, fail to operate with a constant set of parameters and hence may operate with slight variations between one firing and the next. In contradistinction to this, the inventive gas powering unit depends upon the constant forces developed by springs to reseat the gas seal. Hence, while pressure changes affect the operation of the unit to some extent, there is significantly less operational variance exhibited by the inventive unit than is exhibited by each of the units known to the prior art.

In one form of the invention, the nose of the instrument serving as a mount for the cartridge is rotatable with respect to the power pack unit. The output shaft of the power pack unit terminates in a cylindrical region adapted to rotatably associate with an extension which directly drives the pusher of the cartridge. In this manner, the extension, cartridge and mounting nose are free to rotate with respect to the remainder of the instrument, and hence the surgeon can easily align the forward force of the cartridge with the incision to be sutured.

Accordingly, it is one object of the present invention to provide a novel and simplified cartridge for housing a plurality of staples and having the capability of ejecting and forming staples singly in the disunited skin or fascia of a patient.

It is a further object of the present invention to provide a novel staple housing cartridge whose pusher element advances a plurality of staples and ejects and forms such staples singly, requiring only rectilinear motion from a power source.

Yet a further object of the invention is to provide a novel staple carrying cartridge housing a plurality of staples within the teeth of a flexible belt.

Still a further object of the present invention is to provide a staple carrying cartridge housing a plurality of staples along a flexible belt and equipped with a pusher element for advancing each of the staples and the belt and for simultaneously ejecting from said cartridge the forwardmost staple.

Yet another object of the present invention is to provide a compact, inexpensive and disposable cartridge for carrying a plurality of staples and for associating with a powering instrument, the cartridge and instrument serving, together, to join the disunited skin of the patient by means of surgical staples.

A further object of the present invention is to provide a novel and disposable cartridge housing a plurality of staples and designed to associate with an adaptor having anvil means and pusher means, and serving to connect the cartridge to a powering instrument.

Another object of the present invention is to provide a novel staple housing cartridge having simplified means for displaying the number of staples remaining in such cartridge.

A further object of the present invention is to provide a staple housing cartridge having a pusher element whose forward face is stepped in such a manner as to minimize the forces required for forming a surgical staple.

Still a further object of the present invention is to provide a novel adaptor to connect a disposable staple housing cartridge to a powering instrument.

Yet another object of the present invention is to provide a novel and simplified instrument for developing a rectilinear thrust for ejecting staples from an associated cartridge.

A further object of the present invention is to provide a novel gas powered instrument having a simplified power pack assembly.

A further object of the present invention is to provide a novel gas powered instrument having a novel hammer-type trigger assembly.

Still another object of the invention is to provide a novel and simplified stapling instrument which allows for easy assembly of the staples with the incision to be sutured.

These and other objects of the present invention, as well as many of the attendant advantages thereof, will become more readily apparent when reference is made to the following description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of the inventive gas-powered surgical instrument showing its association with a cartridge;

FIG. 2 is a cross-section through the body of a staple carrying cartridge constructed in accordance with the first embodiment of the present invention;

FIG. 3 is a bottom view of the cartridge illustrated in FIG. 2;

FIG. 4 is an enlarged top view of the forward portion of the cartridge illustrated in FIG. 2;

FIG. 5 is a cross-section similar to FIG. 2, illustrating the manner in which the staples change planes of travel during the staple driving operation.

FIG. 6 is a view similar to FIG. 5 showing the cartridge at a later time during the staple driving operation;

FIG. 7 is a view similar to FIG. 5 showing the cartridge during the return stroke of the pusher;

FIG. 8 is a view similar to FIG. 7, but showing an alternate arrangement for preventing retracting of the flexible belt;

FIG. 9 is an enlarged perspective of the forward end of the novel pusher;

FIG. 10 is a front view, partially in section, illustrating the cartridge shown in FIG. 2;

FIG. 11 is a schematic showing an early stage of staple formation in the skin of a patient;

FIG. 12 is a view similar to FIG. 11, but showing a later stage of staple formation;

FIG. 13 is a cross-section through the inventive power pack unit;

FIG. 14 is a side view, partially in section, illustrating the inventive adaptor unit and the second embodiment of the inventive cartridge unit;

FIG. 15 is a partial cross-section illustrating the interaction between the adaptor and the second embodiment of the cartridge;

FIG. 16 is a top view of the nose of the inventive adaptor, with its cover removed;

FIG. 17 is a front view of the second embodiment of the cartridge; and

FIG. 18 is a cross-sectional view through the front end of the inventive gas powered surgical instrument when provided with a freely rotatable nose assembly.

DETAILED DESCRIPTION OF THE DRAWINGS

With reference now to the figures, and particularly with reference to FIGS. 1 through 10, the first embodiment of the inventive cartridge will be described. The cartridge is shown generally at 10 and, in FIG. 1 is shown mounted on a CO.sub.2 power instrument 12. The cartridge 10 comprises, basically, a main body 14 having a pair of side walls 16 and 18, a front wall 20, and a rear wall 22. A solid projection 24, which may connect the side walls 16 and 18, is centrally positioned in the main body 14. A metallic cover 26 encloses the main body at the top thereof and a transparent plate 28 encloses the main body at its bottom. An anvil 44 is made integral with the forwardmost region of the cover 26.

A flexible belt or guide track 30, as of Lexan, polypropylene, or similar material, is fit in the main body 14 and is adapted to slide between the central projection 24 and the cover 26, and to slide between the projection 24 and the bottom plate 28. The flexible belt is substantially planar in configuration but also has a plurality of teeth 32 on one side thereof, between which teeth 32 are defined a plurality of staple carrying grooves or contact surfaces 34. For reasons which will be explained below, every third groove 34 is continuous at the central region 35 of the belt 30, extending entirely through the body of the belt. A staple 36 is housed in and is guided by every third groove 34 of the flexible belt 30. It can be seen that the staples are housed in other than the continuous grooves of the belt 30. A substantially planar and flexible staple pusher 38 is positioned intermediate the flexible belt 30 and the cover 26, and is adapted for linear motion along the length of the cartridge 10. As best seen in FIGS. 2, 4, 9 and 10, while the major portion of the pusher 38 lies above the plane of the staples 36, a pair of downwardly projecting flanges 40, at the forward outermost regions of the pusher 38, are adapted to project into the plane of the staples. The downwardly projecting flanges 40 of the pusher 38 are oriented outside the transverse limits of the flexible belt 30, but associate with the staples 36 through the means of the cross-pieces thereof.

The forward face of the pusher 38 is stepped. The deepest step defines a base 42, of a width equal to the width of the anvil 44 plus slightly more than twice the diameter of a staple 36. The steps defined in the pusher define what may be termed moment points 46, 48 and 50, which serve, as will be explained below, to assist in singly bending the staples 36 around the anvil 44.

The inventive cartridge 10 is provided with means for preventing the movement of the flexible belt 30 in a direction opposite to that indicated by arrow 52 (FIG. 2). These means take the following form. A body of material is removed from the central region of the projection 24. The material is removed, however, so as to define a thin flexible arm 54 having a projection 56, extending, when relaxed, into the plane of the flexible belt 30. The upper surface of the projection 56 is tapered at 58 so that when the flexible belt 30 moves in the direction of arrow 52, the arm 54 is cammed out of the plane of the belt by the full grooves 54.

As noted previously, the bottom plate 28 is formed from a transparent material. Therefore, as can be seen with referencee to FIG. 3, the lower portion of the flexible belt 30 is visible through the transparent plate 28. The plate 28 is provided with a set of indicia which is indicative of the number of staples remaining in the cartridge 10. As the staples are expelled from the cartridge, the belt 30 moves in the direction of arrow 59, with the lead end of the belt aligning with a number on the bottom plate 28. In this manner, the surgeon is always apprised of the need for replacing an exhausted cartridge.

With reference now to FIGS. 4, 5 and 10, the staple guiding mechanism of the inventive cartridge will be described. Over a major portion of the length of the body 10, the arms of the staples 36 are guided along ledges 59 defined in the respective side walls 16 and 18. Near the front face 20 of the cartridge 10, the staples are acted upon by two sets of ramps 60 and 62, respectively. The ramps 60 are spaced apart so as to act on the cross-pieces of the staples 36, while the ramps 62 are spaced apart so as to act on the legs of the staples. The sets of ramps 60 and 62 are longitudinally spaced apart so that when a staple 36 is advanced in the direction of arrow 64 (FIG. 4), it simultaneously engages the sets of ramps 60 and 62 so that the cross-piece and the arms of the staple change planes in unison.

With continuing reference to FIGS. 1 through 10, the operation of the inventive cartridge will now be described. As seen best in FIG. 2, the drive element 55 of the powering instrument 12 extends through a groove 68 in the rear of the pusher 38. As will be explained below, each triggering of the instrument 12 advances the drive element 66 toward the front of the cartridge 10. Therefore, the cover 26 is slotted at 70. And, as in each of the related copending patent applications described above, the movement of the pusher 38 is positively controlled by the drive element 66 of the powering instrument 12.

The cartridge 10 is shipped with the elements in the relative positions illustrated in FIG. 2. When in the operating arena, the pre-sterilized disposable cartridge 10 is removed from its sealed package and is inserted on the instrument 12. As seen best in FIG. 1, the rear of the cartridge cover 26 is provided with at least one upstanding tab 27 adapted to associate with a corresponding at least one notch (not shown) in the body of the instrument 12. The cartridge 10 is advanced toward the powering instrument 12 as shown in solid lines in FIG. 1 and is then moved into the position indicated in phantom. Finally, the U-shaped bracket 74 is moved into the position shown in phantom and the screw 76 is tightened so as to bear on the bottom plate 28 of the cartridge 10. The drive element 66 of the instrument 12 now unites with the slot 68 in the pusher 38 and the cartridge 10 is held fixed with respect to the instrument 12.

When the instrument 12 is fired, the driving element 66 moves forward relative to the cartridge 10. So, too, therefore, does the pusher 38. When the pusher 38 moves toward the foreward face of the cartridge 10, the downwardly extending flanges 40 come into contact with the cross-piece of the forwardmost staple 36. With continued forward movement of the pusher 38, the forwardmost staple 36 is urged forwardly. And, as the forward staple 36 is maintained in its groove 34 (held by the respective outer regions of the sides of the cover 26), the flexible belt 30 is caused to move in the direction of arrow 52. Therefore, each of the staples 36 is advanced in the body of the cartridge 10.

Continued forward movement of the pusher 38, in the direction of arrow 64, brings the cross-piece of the forwardmost staple 36 into engagement with the set of ramps 60 and brings the legs of the staple 36 into engagement with the set of ramps 62. Then, with still further movement of the pusher 38, the forwardmost staple 36 moves in the direction of arrows 78 (FIG. 5), up the sets of ramps 60 and 62, and shifts from the plane of the flexible belt 30 into the plane of the pusher 38. As the staple 36 rises from the plane of the belt into the plane of the pusher, the cross-piece of the staple slides along the respective forward faces of the downwardly extending flanges 40.

During the time when the forwardmost staple rides within the confines of its guiding groove 34, the flexible belt 30 moves in the direction of arrow 52; this movement continues until the staple rises out of its groove and into the plane of the pusher. Further movement of the pusher 38 in the direction of arrow 64 results in the expulsion of the forwardmost staple 36 from the cartridge 10 and the formation of that staple around the anvil 44.

When the pusher 38 is at the forwardmost portion of its stroke, each of the staples 36 has been advanced in the body of the cartridge 10 substantially one complete staple length. And, when the pusher is in this position, the upstanding flange 56 on the flexible arm 54 is in the plane of the flexible belt 30, entering such plane through one of the continuous grooves 34.

After a staple 36 has been formed around the anvil 44, as shown in FIG. 6, the drive element 66 and its integral pusher 38 reverse their respective directions of travel. The pusher 38 begins to retract and continues to do so, unimpeded in any way, until the sloping walls 80 of the downwardly projecting flanges 40 come into contact with the forwardmost staple 36 then remaining in the body of the cartridge 10. As the pusher 38 moves in the direction of arrow 82 (FIG. 7), the downwardly projecting flanges 40 are cammed, by the forwardmost staple, out of the plane of the staples 36 and ride over such forwardmost staple. To allow for this out-of-plane flexing of the pusher 38, the cover 26 is provided with a central raised region 84. Ultimately, the pusher 38 takes the position shown in phantom in FIG. 7, with the flanges 40 lying behind and in the plane of the forwardmost staple 36. This is precisely the position illustrated in FIG. 2, and hence the cartridge is then ready for the next firing operation.

During the movement of the pusher 38, in the direction of arrow 82, and when the sloping or cam surfaces 80 of the flanges 40 are in contact with the cross-piece of the forwardmost staple 36, forces are generated which tend to reverse the movement of the flexible belt 30 and hence the movement of each of the staples associated therewith. Such reversed movement is, of course, undesirable and hence precautions are taken to eliminate the same. It is for this reason that the flexible arm 54, with its upwardly extending projection 56, is fit in the cartridge 10.

As best seen in FIGS. 6 and 7, the projection 56 associates with a continuous groove 34 in the belt 30 when the pusher 38 is in its forwardmost position. In this manner, all reverse forces generated in the belt 30 when the pusher 38 is cammed over the forward staple 36, are dissipated without actual reverse movement taking place in the belt or staples. See FIG. 7. However, the arm 54 with its projection 56 in no way retards the forward movement of the belt and staples. When the pusher 38 drives the belt 30 so as to advance the staples 36, the rear face of the associated continuous groove cams the projection 56 out of the plane of the belt through the action of the sloping wall 58 of such groove. See FIG. 5.

In FIG. 8, an alternate manner of preventing the retraction of the belt 30 and its staples 36 is illustrated. Contrary to the embodiment of the cartridge illustrated in FIGS. 1 through 7, where every third groove 34 is continuous, the FIG. 8 embodiment has no continuous grooves tending to weaken the belt 30. The belt grooves extend only to the base of the belt. In this embodiment, unwanted retraction of the belt 30 and its staples 36 is prevented by the provision of a small spring 86 secured to the bottom plate 28 by a pin 88. When the belt 30 is driven so as to advance the staples 36, the rear faces of the grooves 34 cam the spring 86 out of the plane of the belt. However, when the belt 30 attempts to reverse its direction of travel, during the retraction of the pusher 38, the forward face of the groove 34 in which the spring 86 is biased contacts the spring 86 and prevents movement of the belt.

With reference now to FIGS. 11 and 12, the bending of the staples 36 about the anvil 44 will briefly be described. The staple 36, when in the position illustrated in solid lines in FIG. 11, has just left the domain of the main body 14 of the cartridge 10. The alignment illustrated in this figure is maintained, however, due to the rapid movement of the pusher 38 in the direction of arrow 64 and the association of the arms of the staple 36 with the skin of the patient. Movement of the pusher 38 in the direction of arrow 64 from that position illustrated in solid lines causes the staple 36 to bend as shown in phantom in FIG. 11. The bending occurs as a result of the interaction between the anvil 44 and the pusher 38 acting through moment points 46 of the stepped region thereof.

Further movement of the pusher 38 in the direction of arrow 64, shown in phantom in FIG. 12, causes further bending of the staples 36. This further bending is a result of forces exerted on the staple 36 by the anvil 44 and the moment points 48 of the stepped region of the pusher 38. Still further movement of the pusher 38 causes the staple to take the shape illustrated in solid lines in FIG. 12, the final bending of the staple being the result of forces generated by the anvil 44 and the moment points 50.

The forward face of the pusher 38 is stepped for the following reasons. The initial bending of the staple 36 is the most difficult stage of the bending operation. There are substantial inertial forces which must be overcome before the staple begins to bend; and to facilitate the bending of the staple, a long moment arm is employed. After the staple has begun to bend, the inertial forces are in favor of bending, and hence a shorter moment arm is employed. In this manner, when it is most difficult to bend the staple, the bending forces are greatest; when it is easiest to bend the staple, the bending forces are reduced. Therefore, a relatively constant input force may be used to bend the staple even though the necessary bending forces change during the bending operation.

With reference now to FIG. 13, the novel power pack forming a part of the present invention will be described. The power pack is shown generally at 100 and comprises the following elements. In the specific embodiment disclosed, the main body takes the form of a four-piece unit, comprising circular cylindrical elements 102, 104, 106 and 108, respectively. Unit 102 serves basically to house a CO.sub.2 bottle 110. A piercing pin 112 with a bore 114 passing therethrough is sealed, by O-ring 116, in the rear wall of the cylindrical unit 104, mating with the bottle 110 in the unit 102. A bore 118, extending from the forward face of the unit 104 into the region of the piercing pin 112, is provided in the cylindrical unit 104. Forward of the bore 118 in the cylindrical unit 104 is a piston housing 120 serving to slidably mount a cylindrical piston 122. An O-ring 124 seals the piston 122 against the piston housing 120.

Fixedly imbedded in the rear wall of the piston 122 is a flexible sealing element 126, such as of Celcon. The function of the element 126 is to seat against the wall of the cylindrical unit 104 in which the bore 118 is provided, thereby preventing the CO.sub.2 gas from entering the region of the piston housing 120. A bore 127 passes through the body of the piston 122 and leads from the piston housing 120 to the rear wall of the piston 122. A coil spring 128 biases the piston 122 so as to seat the element 126 against the bore 118 in the cylindrical unit 104.

A cylindrical stop 130 is fixedly mounted in the unit 106 and serves as an abutment for the end of the coil spring 128 remote from the piston 122. A bore 132 passes through the center of the stop 130, while a bore 134 is defined in an extension thereof located intermediate the cylindrical units 106 and 108, respectively.

The rearward nose of the cylindrical stop 130 is of a lesser diameter than is the inner diameter of the cylindrical unit 106 adjacent such nose. A second piston 136 is slidably mounted between the nose of the cylindrical stop 130 and the inner wall of the cylindrical unit 106. The forward face of the piston 136 extends into a ring-like projection 138. Between the projection 138 and the inner wall of the cylindrical unit 106 is an O-ring 140; and between the projection 138 and the nose of the cylindrical stop 130 is an O-ring 142. A coil spring 144 acts between the piston 136 and the cylindrical unit 104, thereby biasing the piston 136 away from the piston 122. At rest, the projection 138 of the piston 136 rests against a rear wall of the cylindrical stop 130.

The internal wall of the cylindrical unit 108 defines a cylinder 146. A main piston 148 slides in the cylinder 146 and is sealed against the wall thereof by an O-ring 150. A rod-like extension 152 is integral both with the main piston 148 and with the drive element 66 (FIG. 2). A coil spring 154 biases the main piston 148 against the forward wall of the cylindrical stop 130.

In addition to the elements described above, the cylindrical unit 104 houses a triggering unit shown generally at 156. The unit 156 comprises a trigger 158 having an oblong bore 160, which trigger is mounted on a pin 162 integral with the cylindrical unit 104. A spring 164 surrounds the pin 162 and biases the trigger 158 in a clockwise direction as shown in FIG. 13 with the lower region of the oblong bore 160 in contact with the pin 162. Integral with the trigger 158 is a tongue 166 extending into the body of the unit 104.

A hammer 168 is slidably mounted in the bore 170 defined in the cylindrical unit 104. The forward face of the hammer 168 is adapted, when at rest, to contact an upstanding flange 171 on the piston 122. A groove 174, having a sloping wall 176 and a flat wall 178, is defined between the forward region of the hammer 168 and the rear region thereof, and associates with the tongue 166 of the trigger 158. A bore 180 extends into the rear of the hammer 168 and accommodates a coil spring 172, biasing the hammer 168 toward the flange 171 on the piston 122. The spring 172 is held in place by means of a plug 174 threaded into the body of the cylindrical unit 104. As noted previously, the spring 164 serves to maintain the base of the oblong bore 160 in contact with the spring 166. This is made possible by contouring the surface of the trigger 158 so that it confortably associates with the upper surface of the hammer 168. A fulcrum is thus defined between the points (or surfaces) of contact between the lower surface of the trigger and the upper surface of the hammer.

The operation of the novel power pack unit is as follows. When the trigger 158 is depressed by the surgeon, the bias of the spring 164 is overcome and the trigger is pivoted in a counterclockwise direction. With the downwardly directed force acting on the trigger 158, the top of the oblong groove 160 is urged into contact with the pin 162. With pivoting of the trigger 158 in the counterclockwise direction, the tongue 166 abuts the wall 178 of the hammer 168 and causes movement of the hammer 168 in opposition to the bias of its spring 172. Such movement continues until the bottom surface of the trigger 158 comes into contact with a pin 182 rigidly secured to the cylindrical unit 104. Then, with continued force being exerted on the trigger 158, the oblong groove 160 moves with respect to the fixed pin 162 until the base of the groove 160 again nears the surface of the pin 162. Before actual contact is made, however, the tongue 166 exits the groove 174, thereby releasing the hammer 168.

When the hammer 168 is released by the trigger 158, it moves under the bias of its spring 172 and impacts the upstanding flange 171 of the piston 122, causes movement of the piston against the bias of its coil spring 128, and thereby unseats the element 126 from the adjacent wall of the cylindrical unit 104. Immediately after the element 126 is unseated, the piston 122 is acted upon by CO.sub.2 gas escaping through the bore 118 and into the piston housing 120. The combined inertial forces of the moving piston 122 and the forces exerted by the pressurized CO.sub.2 gas cause the piston 122 to seat against a flexible sealing element 184 integral with the nose of the cylindrical stop 130. With the pressurized CO.sub.2 gas free to escape from the bottle 110 into the piston housing 120, and with the piston 122 seated against the cylindrical stop 130, pressurized gas passes through the piston 122, via bore 127, through cylindrical stop 130, via bore 132, and enters a small volume chamber defined between the large area rear face of the main piston 148 and the front face of the cylindrical stop 130. Acting on the large area surface, the pressurized gas exerts a substantial thrust against the main piston 148 causing the main piston to rapidly travel in the direction of arrow 188. As noted previously, such action activates the staple carrying cartridge.

With the main piston 148 executing a staple driving stroke, a substantial pressure is generated in the cylinder or piston chamber 146. In response to such pressure, gas is caused to exit the cylinder 146, through the port 134, and enter the region of the slidable piston 136. Such gas pressure causes movement of the piston 136 against the bias of its spring 144.

It will be remembered that during the forward stroke of the main piston 148, the piston 122 seats against element 184. The upstanding flange 171 contacts or comes in close proximity to the forwardmost face of the piston 136. Therefore, movement of the piston 136 to the right (FIG. 13) causes engagement between the forwardmost face of such piston and the upstanding flange 171 of piston 122. As a consequence of this, piston 122 moves to the right, reseats itself against the adjacent wall of the cylindrical unit 104, and prevents further escape of the CO.sub.2 gas into the piston housing 120, biased by its coil spring 128.

With the port 118 sealed against the passage of CO.sub.2 gas, the main piston 148 is free to return to its rest position, biased by its spring 154. At the same time, the pressure is relieved on the left side of the piston 136 via passage 134 and such piston moves to the left in response to the bias of its coil spring 144. In this manner, each of the elements of the power pack are returned to their rest positions illustrated in FIG. 13.

The main advantage of the inventive power pack is that once the piston 122 is reseated, sealing the port 118, the constant force coil spring 128 maintains such seating. In contradistinction to this, prior art power packs maintain the seating mainly by gas pressure. And, because the gas pressure varies somewhat with the number of cycles developed by the CO.sub.2 bottle, the reseating mechanism of the prior art power packs tend to be somewhat unpredictable in nature. However, with the positive and constant force reseating mechanism of the present invention, positive and predictable reseating results.

With reference now to FIGS. 14 through 17, the second embodiment of the inventive cartridge, and the inventive adaptor, will be described. The inventive cartridge is shown generally at 200 and the inventive adaptor at 202.

The cartridge 200 comprises, basically, a main body 204 having a central projection 206 (FIG. 15) similar to that shown at 24 in FIG. 2. A flexible belt, elongated linkage or guide track 208 rides within a fixed guide member 210 defined between the central projection 206 and the body 204 of the cartridge 200. As with the first embodiment of the present invention, the belt is toothed on one side thereof, and ever third tooth houses and guides a staple. A pusher 212 is contained between the top surface of the body 204 and the flexible belt 208. The forward face of the pusher 212 is provided with a pair of downwardly projecting flanges 214 identical to those described with reference to the first embodiment of the present invention. A small opening 216 is provided in the rear of the pusher 212 and is adapted, as will be explained below, to mate with a downwardly projecting flange 218 integral with a pusher extension 220 in the adaptor 202. As seen in FIGS. 14 and 17, the forward face of the cartridge 200 is open, with the flexible belt 208 exiting the cartridge at theeupper region thereof, looping around and reentering the cartridge in the lower region of the guide member 210.

The cartridge 200 described above is adapted to house on the order of 30 to 40 staples. It can be seen that as the flexible belt 208 substantially forms a closed circuit around the guide member 210, such a substantial staple handling capacity results. If, on the other hand, it is desired that only six to 12 staples be housed, the body of the cartridge 200 may be made smaller, as indicated by the dash-dot line 222 in FIG. 14. With this arrangement, theestaples would be linearly housed within the body of the cartridge.

The adaptor 202 comprises, basically, a main body 224, a cover plate 226 rigidly mounted on the main body 224, a nose 228, a cartridge lock 230, and a pusher extension 220. The rear region of the cover 226 is provided with at least one upstanding tab 232 to secure the adaptor 202 to the power instrument 12 (as in FIG. 1). An anvil 234 is integral with the cover plate 226 and is provided at the forwardmost end thereof.

As seen in FIGS. 14 and 15, the nose 228 of the adaptor 202 is constructed so as to mate with the forward face of the cartridge 200. The cartridge 200 is associated with the adaptor 202 as follows. First, the forward face of the cartridge 200 is advanced toward the nose 228 of the adaptor 202 in the direction of arrow 236. Then, once the forward regions of the cartridge and adaptor are in contact, the rear of the cartridge 200 is moved in the direction of arrow 236 until the cartridge lock 230 snaps into a detent 238 in the body of the cartridge 200. Then, the cartridge is ready to be fired.

It should be noted that the disposable cartridge 200 is far more simple than is the disposable cartridge 10 described above. The pusher 212 is substantially smaller than is the pusher 38. There is no elongated metal cover to associate with the cartridge 200, nor is the cartridge 200 provided with an integral anvil. Further, and as shown in FIG. 16, the sets of ramps 240 and 242 are integral with the adaptor 202 rather than with the disposable cartridge 200. These sets of ramps serve the same function as do the sets of ramps 60 and 62 of FIG. 4. Again, therefore, the design of the cartridge 200 is simplified. In all other respects, the operation of the inventive cartridge 200 is identical with that of the inventive cartridge 10.

A further embodiment of the inventive gas-powered surgical instrument is illustrated in FIG. 18. In this embodiment, the cylindrical body unit 108 is provided with a cylindrical abutment 282 at its forward end and is attached to cylindrical element 106 in the same manner as is illustrated in FIG. 13. A piston chamber 284 is defined by the interior of cylindrical unit 108 and serves as a housing for the main piston 148 sealed in piston chamber 284 by O-ring 150.

A nose 290, shaped in the form of a truncated cone, is rotatably attached to the leading end of cylindrical body unit 108. Nose 290 is provided with a threaded cylindrical extension 292 which fits inside the forward cylindrical abutment 282 of unit 108. A nut 296 is threaded onto extension 292 and abuts the rear face of abutment 282. A slight clearance is maintained between nut 296 and the adjacent face of cylindrical abutment 282 so that nose 290 can freely rotate with respect to the cylindrical unit 108.

A preferably cylindrical channel 298 is bored axially through nose 290, and the lower portion of the truncated cone defining nose 290 is cut away so that the nose is sized and shaped to receive an inventive cartridge in a manner described above with reference to FIG. 1. The cut is made at 299 and opens the channel 298 for the free passage of the drive element 66. The rod-like extension 152 is located in channel 298 for driving the pusher of an associated cartridge. In addition, nose 290 is provided with means such as a bracket and screw (not shown) for holding the inventive cartridge in a manner previously described. The rearward end of extension 152 is screw-fit into the forward surface of main piston 148 in piston head 286.

With this design, nose 290, extension 152, and hence the associated cartridge, carried by nose 290, can be freely rotated about a longitudinal center line to any desired angle. This feature allows great flexibility in the positioning of the cartridge, and hence eases the task of the surgeon in those situations when the incision to be sutured is not conveniently positioned.

Above, several embodiments of the present invention have been described. It should be appreciated, however, that these embodiments are described for purposes of illustration only and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is the intent that the invention not be limited by the above but be limited only as defined in the appended claims.

Claims

What is claimed is:

1. A gas-powered driving unit for converting gas pressure into rectilinear motion, the unit comprising: an elongated casing unit; a gas inlet port at one end of said elongated casing for the introduction of pressurized gas into the body of said main casing; a first piston chamber continuous with said gas inlet port, of a diameter substantially larger than that of said gas inlet port, and extending along the length of said elongated casing unit; a piston-like valve seat slidably mounted in said first piston chamber, said valve seat having a bore therethrough for communicating said first piston chamber with the extremity of said valve seat remote from said gas inlet port; an abutment block positioned adjacent said piston-like valve seat, fixed with respect to said elongated casing unit and positioned on the side of said valve seat remote from said gas inlet port, said abutment block having a bore extending from one end thereof to the other, thereby defining uninterrupted communication between the end of the block remote from said gas inlet port and the bore in said valve seat; a seating piston mounted for reciprocation in a second piston chamber defined in said casing unit, and positioned intermediate said valve seat and said abutment block a driving piston mounted for reciprocation in a third piston chamber defined in said elongated casing unit, adjacent said abutment block and located on the side thereof remote from said gas inlet port; first biasing means for biasing said piston-like valve seat away from said abutment block and against said gas inlet port; second biasing means for biasing said seating piston away from said piston-like valve seat; and third biasing means for biasing said driving piston toward said abutment block.

2. A gas-powered driving unit recited in claim 1, and further comprising: trigger means for moving said piston-like valve seat away from said gas inlet port, thereby allowing the passage of pressurized gas from said inlet port into said first piston chamber and thereby initiating a drive stroke of said driving unit.

3. The gas-powered driving unit recited in claim 2, wherein said seating piston is idle until after the initiation of the driving stroke and after the pressure in the elongated casing unit have equalized; and wherein said seating piston then serves to abut against said valve seat and to drive said valve seat into communication with said gas inlet port, thereby sealing off the source of pressurized gas from said first piston chamber.

4. The gas-powered driving unit set forth in claim 3, wherein said seating piston is driven toward said valve seat, after pressure equalization, by gas pressure and against the biasing force developed by said second biasing means.

5. The gas-powered driving unit recited in claim 4, wherein the first biasing means is of sufficient strength to maintain the piston-like valve seat against the gas inlet port in opposition to the gas pressure developed in said gas inlet port, but is of strength insufficient to move the valve seat toward the gas inlet port in opposition to the gas pressure developed in said first piston chamber.

6. The gas-powered driving unit described in claim 4, wherein said piston-like valve seat, after triggering of the driving unit and the equalization of pressures in the casing unit, is driven toward said gas inlet port by the combined combined forces exerted by said seating piston and said first biasing means.

7. The gas-powered driving unit recited in claim 6, wherein said first and second biasing means take the form of coil springs.

8. The gas-powered driving unit recited in claim 2, wherein said trigger means is in the form of an impact device; wherein the operation of said impact device is mechanically initiated by an operator; and wherein said piston-like valve seat is moved off of said gas inlet port by an impact delivered by said impact device.

9. The gas-powered driving unit recited in claim 1, and further comprising a cartridge mount for associating a staple-housing cartridge with said driving unit, said cartridge mount attached to said elongated casing unit on the side adjacent said third piston chamber and remote from said gas inlet port.

10. The gas-powered driving unit recited in claim 9, wherein said cartridge mount is defined by a stationary element rigidly attached to said elongated casing unit and a movable element rotatably attached to said stationary element.

11. The gas-powered driving unit recited in claim 10, wherein said movable element is adapted to rotate about an axis parallel to the longitudinal center line of said staple-housing cartridge as oriented when associated with said driving unit.

12. The gas-powered driving unit recited in claim 10, wherein said movable element is adapted to rigidly receive said staple-housing cartridge.

13. The gas-powered driving unit recited in claim 12, and further comprising drive means rigidly attached to said driving piston for associating with and driving said staple-housing cartridge, wherein said drive means and said staple-housing cartridge rotate as said movable element is rotated.

14. A surgical stapling instrument for applying sterilized staples to the disunited skin of a patient for effecting the joining of the skin, the instrument being adapted to accept a staple-housing cartridge and comprising: a main body portion defining abutment means; mounting means rotatably mounted to said main body portion at the forward end of said main body portion for releasably rigidly holding said staple-housing cartridge and associating same with said surgical stapling instrument; and driving means for delivering power from said instrument to said cartridge for ejecting staples from said cartridge and clinching same in the disunited skin of the patient, said driving means including an elongated shaft having a coupling element at the forward end and a piston at the rear end, said mounting means comprising a nose defining a threaded extension which fits inside said abutment means and nut means secured to said threaded extension to abut the rear face of said abutment means so that said mounting means is rotatably associated with said main body portion in such a manner that said staple-housing cartridge rigidly associated with said mounting means can be rotated relative to said main body portion.