SURGICAL STAPLER

Abstract: A staple cartridge for use in skin and fascia closure of the type in which staples in the course of their ejection from the cartridge are formed about an anvil (37) located at the forward end of the cartridge, in which for the purpose of preventing excessive penetration of staples into the tissue, projections (53) extend beyond the forward surface of the anvil on either side thereof.

Description: SURGICAL STAPLER TECHNICAL FIELD This invention relates to surgical stapling instruments for the skin and fascia, of the type in which staples are housed and dispensed from a disposable cartridge, the staples in the course of their ejection from the cartridge being formed about an anvil located at the forward or skin-contacting end of the cartridge. BACKGROUND ART One form of such an instrument is described in Canadian patent specification 998308. In this instrument, the staples are located in spaced grooves in a flexible continuous belt within the cartridge, and are advanced by the engagement of a pusher with the foremost staple on each forward movement, the pusher advancing the staple into engagement with the anvil, and forming the staple about the anvil by means of an appropriately shaped stepped formation at the forward end of the pusher. The anvil consists of an integral portion of the metal cover of the cartridge at its forward end, projecting into the plane of the pusher. In this and other types of known cartridges for stapling skin or fascia, the anvil is located in, or substantially in, the plane of the forward end of the instrument, so that in operation, the outer, non-working, surface of the anvil contacts the skin or fascia during a stapling operation. This arrangement has been found to suffer from the disadvantage that if the anvil is pressed too firmly against the skin during stapling, the free ends of the staples may penetrate too deeply into the under¬ lying tissue before being- bent beneath the skin or fascia surface by the action of the pusher and anvil. This may result in suturing with excessive compression of the tissue between the staple arms, resulting in difficult and painful removal of the staples, and may allow the staple to catch underlying muscular tissue or bone. DISCLOSURE OF THE INVENTION The object of the present invention is to reduce the likelihood of such excessive staple penetration, and this is achieved by the provision of projections at the forward end of the cartridge, which extend substantially beyond the forward surface of the anvil, these projections contacting the skin or fascia during staple insertion. In this way, forceful contact of the anvil with the skin or fascia is prevented and excessive penetration of the staples under the conditions referred to above, is substantially avoided. ' BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a plan view of a staple cartridge embodying the present invention. Figure 2 is a side elevation of the cartridge illustrated in Figure 1. Figure 3 is a longitudinal cross-section taken on the line 3-3 of Figure 1. Figure 4 is a front elevation of the cartridge illustrated in Figures 1 and 2. Figure 5 is a lateral cross-section taken on the line 5-5 in Figure 1. Figure 6 is a plan view of a pusher element. Figure 7 is a side elevation of the pusher element illustrated in Figure 6. Figure 8 is a plan view of a spring. Figure 9 is a side elevation of the spring illustrated in Figure 8. Figure 10 shows in side elevation the front portion of a modified form of the cartridge illustrated in Figures 1 and 2. BEST MODE OF CARRYING OUT THE INVENTION The cartridge illustrated in the accompanying drawings is generally of a type known in the prior art and currently used in skin closure. As shown in the drawings, the cartridge consists of a metal cover 20 having an upper surface 21 and a pair of side surfaces 22, which cover substantially encloses, with the exception of the underneath portion of the cartridge, a plastics body 23.- The body 23 is fixed in its correct longitudinal position within the cover 20 by means of lateral extensions 24 which engage within recesses 25 provided in the lower edge of the side surfaces 22 of the cover 20 towards the rear of the cartridge. The body 23 is fixed within the cover 20 by means of inwardly bent lugs 26 in the side walls 22 which co-operate with slotted formations 27 provided in the side surfaces of the body 23. As is well known, a cartridge of the general type illustrated is adapted for co-operation with a staple driving instrument by the insertion of the rear end of the cartridge into such an instrument, and for the purpose of correct alignment of the cartridge within such an instrument a pair of upstanding flanges 28 are provided at the rear of the cover 20. As is most clearly shown in Figures 3 and 5, the plastics body 23 comprises a bottom wall 29 and a pair of side walls 30. Within these walls 29 and 30 there is mounted a central body portion 31 which fits snugly between the side walls 30 and rests, by means of a downwardly directed flange 32, on the bottom wall 29 as seen in Figure 5. Each end of the central body portion 31 is rounded at 33 (Figure 3), and surrounding the central body portion 31 is a flexible belt 34 of plastics material such as polypropylene. As in the prior art, this belt is provided continuously throughout its length with lateral grooves as shown for example at 35 in Figure 3, for the reception and carriage of staples 36, the cross-bar of each staple resting within a groove 35.. At the forward end of the cartridge an anvil 37 is provided, consisting of a downwardly bent portion of the metal cover 20. As is well known, O PI in the operation of the instrument staples are successively advanced towards the anvil 37, and bent around the anvil 37 during their penetration of the skin, the forward end of the cartridge being held firmly against the skin while the staple is formed around the anvil. To this end, the cartridge further comprises a pusher element 38 which is mounted between the inner surface of the upper wall 21 of the cover 20 and the belt 34. The pusher element 38 is guided in its longitudinal movement by shoulders 39 formed in the upper wall 21 of the cover 20 by longitudinal depressions of the marginal portions of the wall 21. At the rear end of the pusher element 38 there is provided a slot 40 and a pair of upwardly disposed lugs 41 and 42 for the driving engage¬ ment of the pusher element 38 with the mechanism of the staple powering instrument. The lugs 41 and 42 move within a slot 43 extending longitudinally in the upper wall 21 of the cover 20. At the forward, staple engaging, end of the pusher element 38 there are provided a pair of staple engaging and staple forming prongs 44 as are well known in the prior art, these portions depending downwardly from the plane of the pusher element 38 for engagement with the cross-bar of successive staples. The forward portion of the pusher element 38 is also provided with a longitudinally extending slot 45 for a purpose described below. The remaining integer of the illustrated cartridge is a spring 46 illustrated tn Figures 8 and 9 where the spring is shown in its relaxed condition prior to the assembly of the cartridge. This spring 46 comprises a pair of forwardly and downwardly arcuately extending arms 47, a central T-shaped body portion 48 and a central forwardly and downwardly extending arm 49 connected with the body portion 48 by means of a rearward extending portion 50. As will be seen from Figures 1 and 3, the body portion 48 of the spring 46 rests snugly against the upper surface of the body 20. By means of downwardly bent portions 51 passing through apertures 52 in the upper wall 21, the spring arms 47 extend forwardly within the cartridge to straddle the anvil 37 functioning, as is known in the prior art, to assist in the release of staples from the anvil 37 at the conclusion of staple formation. The junction of the spring portions 49 and 50 passes through the cover upper wall 21 at aperture 52 so that the arm 49 extends forwardly above the belt 34, the distal end of the arm 49 engaging with the belt grooves 35 to prevent rearward movement of the belt upon retraction of the pusher element 38. This arm 49 passes through the slot 45 in the pusher 38, this slot extending over a sufficient length of the pusher 38 to enable its reciprocation without interfering with the arm 49. As will have been appreciated, the features of the cartridge thus far described are included in the prior art. The characteristics by which cartridges of the present invention are distinguished from those presently employed are concerned with the arrangement of the housing at the region of the anvil 37. As will be observed in Figures 1, 2 and 3, the cartridge body 23 is extended forwardly for a substantial distance beyond the anvil 37, by projections 53. As indicated in the preamble hereof, the function of these projections is to ensure that, when the anvil end of the cartridge is pressed firmly against the skin or fascia tissue, the anvil 37 cannot bear so heavily against the skin or fascia as to depress the surface to an extent which would allow excessive penetration of the staple into the tissue. The extent to which the projections 53 should project beyond the anvil 37 will vary according to the particular type of cartridge employed, whether that be a cartridge for skin wound closure employing narrow or wide staples, or a cartridge for closure of internal tissue. It will be appreciated also that the surface area of the projections 53, or their equivalents, will also be a factor in determining the correct projection distance. It has been found that in the case of the illustrated embodiment employed for narrow skin closure that staples of 10 m.m. width and with projections 53 having a width of 4 m. ., the projections 53 should extend approximately 4 m.m. beyond the front surface of the anvil 37, while in the case of 15 m.m. staples with the projections 53 having a width of 6 m.m., an extension of the projections 53 of - approximately 3 m.m. beyond the front surface of the anvil 37 is adequate. While the use of projections 53 is the preferred manner in which the present invention is applied to a cartridge of the type illustrated, it will be understood that many alternative arrangements are possible, and are embraced within the scope of the present invention.. For example there is shown in Figure 10 an alternative arrangement whereby the,side walls 22 of the cartridge cover are.extended at 54 to produce a similar effect. Other arrangements, such as the extension of the upper surface 21 of the cartridge cover 20, or the extension of both the cover and the body, will be apparent to the skilled reader.

Claims: AMENDED CLAIMS (received by the International Bureau on 27 May 1981 (27.05.81)) AMENDED) 1. A surgical stapling instrument for the insertion of metal staples into the skin or fascia, comprising an elongated staple carrying cartridge having at its forward end an anvil about which staples are bent during insertion, characterised in that the cartridge is provided with projecting means extending forwardly of the anvil to contact the skin or fascia during staple insertion, said means extending beyond the anvil for such a distance as substantially to prevent forceful contact between the front surface of the anvil and the skin or fascia. 2. A surgical stapling instrument according to claim 1, further characterised in that the cartridge comprises an outer cover and a body mounted substantially within said cover, the body extending forwardly beyond the anvil on either side thereof to form said projecting means. 3. A surgical stapling instrument according to claim 1, further characterised in that the cartridge comprises an outer cover extending forwardly beyond the anvil on either side thereof to form said projecting means. ^NCELLED) 4. 4®&

Inventors: BLACKMAN A
Applicants: BLACKMAN A, HOSPITAL PROD INT PTY
Application year: 1981
Main classification: A61B17
IPC codes: A61B17