INSERTION DEVICE, INSERTION SYSTEM AND SURGICAL INSTRUMENT
SYSTEM
The present invention relates to an insertion device and system for a surgical instrument, and in particular to insertion devices for use with circular staplers.
In a gastric bypass operation using the Roux-en-Y method it is necessary to insert a circular stapler into the body of the patient through an incision that has previously been used for smaller instruments. Typically the incision used before the circular stapler is inserted will be under 10 mm in diameter, while the circular stapler may have a diameter of 21 mm or greater. It is therefore necessary to increase the diameter of the existing incision to a sufficient size that a circular stapler can pass through it.
Various methods and instruments have been proposed to expand the existing incision. In many procedures the surgeon will manually tear the incision wider. This is not ideal because it may damage the abdominal wall and increase the chance of the patient suffering a hernia in later life. It also can require some force from the surgeon, making it difficult to control the tearing.
Devices to ease the insertion of a circular stapler have been proposed. US-2007/0198045 Al (Morton et al) discusses a dilating device that can dilate an orifice to facilitate the introduction of a surgical instrument such as a circular stapler. The dilating device includes a three dimensional dilating surface that functions to dilate an orifice, an alignment surface that functions to align and centre the dilating device, a coupling element that functions to couple the dilating device to the surgical instrument and a removal element to assist in removal of the dilating device from the body cavity.
In one embodiment, the dilating device of Morton et al has a conical dilating surface and includes a conical alignment surface with an angle of opening greater than the angle of opening of the dilating surface. In an alternate embodiment the dilating surface may be parabolic so that it functions to both align the device and dilate the orifice.
The device of Morton et al presents difficulties in use because despite the alignment surface it is still difficult to insert the device along the path previously made by the trocar and catmula. Furthermore, the device of Morton et al is designed for a specific size of surgical stapler and an inventory of different sizes is required for each size of surgical stapler. The present invention aims to address one or more of these difficulties.
According to a first aspect, the present invention provides an insertion device for a medical instrument, wherein the insertion device comprises: a distal portion having an external surface; an intermediate portion adjacent the distal portion, having an external surface which defines a cross section perpendicular to a longitudinal axis that increases in the direction away from the distal portion; and a proximal portion adjacent the intermediate portion, configured to engage a surgical instrument; wherein at the transition between the distal portion and the intermediate portion, the external surface of the distal portion and the external surface of the intermediate portion define an angle which is less than 180 degrees.
The proximal portion can be configured to engage a surgical instrument in any suitable way, including a press-fitting or using an anvil.
It has been found that the tissue tends to close in on itself when the trocar and cannula are removed. This can make it difficult the path followed by the trocar and cannula when inserting the surgical instrument. In use, the distal portion functions to open the incision before the intermediate portion enlarges it. It has been found that the device is easier to insert and remove if the distal portion has an external surface that meets the intermediate portion at an angle of less then 180 degrees. This has the result that the incision is opened for its full depth before it is enlarged, rather than opening and enlarging the incision
simultaneously as with prior art devices.
Morton et a! teaches that an insertion device should have a blunt end and proposes embodiments in which the diameter of the device increases more rapidly at the distal end than towards the proximal end. However, this makes it difficult to insert and remove because it is both opening the incision and enlarging it at the same time as it passes through the abdominal wall. In contrast, a device according to this aspect provides a distal portion which can open the incision before the intermediate portion enlarges it.
Preferably the external surface of the distal portion defines a substantially constant cross section perpendicular to the longitudinal axis. This means that the distal portion is generally straight although it may optionally have a rounded distal end. The straight section can function simply to open the incision without enlarging it. It also has the advantage that it can be used to grasp the device for removal from the body cavity after use. In a preferred embodiment, the distal portion is substantially cylindrical.
The increasing cross section of the intermediate portion functions to open the incision to a diameter such that the surgical instrument can pass through it. The intermediate portion is preferably substantially conical, although other profiles may also be used providing that the cross sectional area increases towards the proximal end.
The intermediate portion may further comprise a screw thread on at least a part of its external surface. The screw thread can assist the opening of the incision by the insertion device. It helps the surgeon to impart a rotational motion, allowing the incision to open more easily. In one embodiment, the screw thread is a helical thread.
The insertion device may be expandable in a radial direction about the longitudinal axis.
This allows the insertion device to be adjusted for use with surgical instruments of different diameters. The expansion may be achieved by any suitable means, for example splitting the device into longitudinal struts joined in a circumferential direction with linkages or a bellows-type construction.
The proximal portion may delimit an opening or cut-away. This can provide features so that the insertion device can be removed more easily from the surgical instrument. It has been found that a "vacuum" type effect can act to make the insertion device difficult to remove when it is attached to the surgical instrument by a press fitting. The opening or cut away reduces this effect.
The intermediate portion may have a stepped profile. This allows the surgeon to pause during insertion, allowing the muscle to relax and reducing the likelihood of tearing. In one embodiment the intermediate portion comprises a proximal enlarging portion, a distal enlarging portion and a cylindrical portion between the proximal enlarging portion and the distal enlarging portion, thereby forming a stepped profile.
According to another aspect of the present invention, there is provided an insertion device for a medical instrument, wherein the insertion device comprises: a distal portion having an external surface which defines a cross section perpendicular to a longitudinal axis that increases in the direction away from a distal end; a proximal portion adjacent the distal portion, configured to engage a surgical instrument; and a screw thread on at least a part of the external surface of the distal portion.
The screw thread allows the device to enlarge an incision more easily by assisting the surgeon to rotate the device.
According to another aspect of the present invention, there is provided an insertion device for a surgical instrument, wherein the insertion device comprises: a distal portion having an external surface which defines a cross section perpendicular to a longitudinal axis that increases in the direction away from a distal end; and a proximal portion configured to engage a surgical instrument; wherein the insertion device is expandable in a radial direction relative to the longitudinal axis.
This allows the insertion device to be adjusted for use with surgical instruments of different diameters. The expansion may be achieved by any suitable means, for example splitting the device into longitudinal struts joined in a circumferential direction with linkages or a bellows-type construction.
According to a further aspect of the invention, there is provided an insertion device for a medical instrument, wherein the insertion device comprises: an enlarging portion having proximal and distal ends and a stepped profile; and a proximal portion adjacent the proximal end of the enlarging portion, configured to engage a surgical instrument.
The reference to the stepped profile refers to the cross section of the device in a plane passing through a longitudinal axis. A stepped profile provides portions which do not enlarge the incision to allow the muscle to relax before further enlargement. This reduces the risk of tearing during enlargement.
The enlarging portion may comprise a generally cylindrical portion between a first, proximal enlarging portion and a second, distal enlarging portion wherein both the first enlarging portion and the second enlarging portion define a cross section perpendicular to a longitudinal axis that increases in the direction away from the distal end. The first and second enlarging portions may be generally conical or have other shapes.
According to another aspect of the present invention, there is provided an insertion device for a surgical instrument, wherein the insertion device comprises: a distal portion comprising engaging means for engaging an introducer member, and for allowing movement of the distal portion along the introducer member; an intermediate portion adjacent the distal portion, having an external surface which defines a cross section perpendicular to a longitudinal axis that increases in the direction away from the distal portion; and a proximal portion adjacent the intermediate portion, configured to engage a surgical instrument.
The introducer member may be used to open the incision. The insertion device can then be guided through the incision by following the introducer member. This provides more reliable expansion of the incision because the insertion device is required only to expand the incision, not also open it.
The engaging means may be a through-hole formed in the distal portion. In that case the insertion device can be guided by the introducer member by guiding the introducer member through the through hole.
Alternatively, the engaging means may comprises a recess and in that case the insertion device can be guided by engaging the recess with a corresponding ridge or groove on the introducer member.
In another embodiment, the engaging means may be a rounded end. The insertion device can then be guided by engaging a longitudinal groove or recess on the introducer member.
The above described aspect may from part of an insertion system which further comprises an introducer member. The introducer member may be substantially cylindrical for use when the insertion device has a through hole. Alternatively, the introducer member may have a longitudinal axis and the external surface of the introducer member defines a ridge aligned with the longitudinal axis for engaging the recess in the insertion device. In another embodiment, the introducer member could comprise a longitudinal recess along its length forming a channel for engaging the engaging means of the insertion device. For example, in one embodiment the introducer member could have a generally "U" shaped cross section.
Any of the above described aspects may be used with a surgical instrument having a distal portion for attachment to the proximal portion of the insertion device to form part of a surgical instrument system. The surgical instrument may be a circular stapler, although the present invention may be used with any other surgical instruments which are required to be inserted through an incision which is smaller than that required by the instrument.
Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic representation of a perspective view of an insertion device according to a first embodiment of the present invention; Figure 2 is a diagrammatic representation of a cross-section of an insertion device according to another embodiment of the present invention; Figures 3A-3D depict diagrammatic representations of cut away portions or holes in the proximal portion of an insertion device according to alternative embodiments of the present invention; Figures 4A and 4B depict diagrammatic representations of an insertion device according to another embodiment of the present invention that can expand in the expanded and contracted positions, respectively; Figure 5 depicts a diagrammatic representation of an alternative embodiment of the insertion device of the present invention that can be expanded; Figure 6 depicts a diagrammatic representation of an embodiment of an insertion system according to the present invention; Figure 7A depicts a diagrammatic representation of an alternative embodiment of an insertion system according to the present invention; Figure 7B depicts a diagrammatic representation of a cross section through the introducer member of the embodiment of Figure 7A; Figures 8A-8C depict the use of the insertion system of Figure 6 to insert a surgical instrument into the body of a patient; Figure 9 depicts a diagrammatic representation of an insertion device according another embodiment of the present invention; Figure 10 depicts a diagrammatic representation of an insertion device according another embodiment of the present invention; Figure 1 depicts an insertion device 2 according to a first embodiment of the present invention. The insertion device 2 comprises a distal portion 4, an intermediate portion 6 and a proximal portion 8.
The distal portion 4 is cylindrical in this embodiment, so that it fonns a generally straight portion at the distal end of the insertion device 4. The distal end is rounded so that sharp edges which could damage body tissue are minimised. A through hole 10 is formed in the distal end. Adjacent the distal portion 4 is the intermediate portion 6. Intermediate portion 6 is cone shaped so that its cross sectional area perpendicular to a longitudinal axis increases towards the proximal end. As can clearly be seen in Figure 1, at the transition from the distal portion 4 to the intermediate portion 6, an angle 0 is formed which is less than 1800. In this embodiment 0 is approximately 165° however, in other embodiments other values may be used providing that 0 is less than 180°. The value of 0 determines at rate at which the incision is expanded by the intermediate portion 6 (discussed in more detail below).
Adjacent the intermediate portion 6 is the proximal portion 8. Proximal portion 8 is generally tubular allowing it to be press fitted to the end of a surgical instrument. Cut outs 12 are formed at the proximal end of the proximal portion 8. They serve two purposes, firstly to reduce the "vacuum" or suction effect that could make it difficult to remove the insertion device 2 from the surgical instrument. Secondly, they give more flexibility to the proximal portion so that it can be more easily fitted to a surgical instrument and more securely retained by the innate resilience of the material.
In this embodiment, the distal portion 4 is about 25 mm long and about 6 mm in diameter.
The intermediate portion 6 is about 40 mm long and increases from a diameter of about 7mm to about 28mm at it's proximal end. The proximal portion extends for about 16 mm.
In other embodiments these dimensions may be altered depending on factors such as the amount of enlargement required, the size and depth of the existing incision and the size of the surgical instrument to which the insertion device is to be attached.
The insertion device is preferably manufactured by machining an autoclavable material so that it is reusable, for example acetal copolymer. Alternatively, if the insertion device is intended to be disposable and not reusable it may be formed by injection moulding with a material such as polypropylene.
In use, the proximal portion 8 insertion device 2 is press fitted to the distal end of a surgical tool, preferably a circular stapler. A length of suture is optionally attached to the through hole 10, leaving sufficient length so that a part of the suture will remain outside the patient when the insertion device is in a body cavity.
The surgeon then proceeds to insert the insertion device through an existing incision. The distal portion 4 serves to open the incision but is not large enough to dilate the incision further. As the insertion device continues to be inserted, the intermediate portion 6 engages the abdominal wall at the point of the incision. The expanding cross section of the intermediate portion 6 then enlarges the incision to a size sufficient that the surgical instrument can pass through it in a controlled manner. The distal portion 4 ensures that the incision is open for the enlargement so that the enlarging is more controlled and reliable than when the incision is both opened and enlarged at the same time. Further insertion of the insertion device 2 moves the proximal portion into contact with the abdominal wall and guides the surgical instrument into the body cavity.
Next, the insertion device is removed from the surgical instrument and placed to one side inside the body cavity. The cut outs 12 assist removal by reducing and vacuum effect that might act to retain the insertion device 2 on the surgical instrument. When the insertion device 2 is used with a circular stapler in the Roux-en-Y procedure there is sufficient space for the insertion device 2 to remain in the body cavity while the procedure is carried out.
With the press fit used in this embodiment, the insertion device is mainly kept in place on the surgical instrument by the combination of external forces acting on it. Firstly, there is the force of the surgeon pressing the surgical instrument and the insertion device into the incision. Secondly, there is a corresponding reaction force exerted as a result of the resistance of the abdominal wall to the passage of the insertion device. This keeps the insertion device in place and ensures easy removal once the device is fully in the body cavity because there is then no reaction force to hold it in place.
Once the procedure is complete the surgical instrument is removed. The insertion device is then removed from the body cavity. This can be done either by grasping the distal portion 4 with surgical graspers or by pulling the suture which remains outside the body.
Alternatively a small loop of suture may be provided attached to the through hole 10. This will remain inside the body and not extend outside it but can still be used to remove the insertion device 2 by grasping the loop of suture with surgical graspers.
A cross section of an alternate embodiment of an insertion device 14 according to the present invention is depicted in Figure 2. This embodiment is the same as first described above except that it is manufactured from silicone. As can be seen in the cross section, the insertion device includes a distal portion 16, intermediate portion 18 and proximal portion 20. The properties of silicone enable the intermediate portion 18 to be manufactured from solid silicone, as shown in Figure 2. This provides a stable surface for enlarging the incision but the innate flexibility of the silicone assists removal.
Figures 3A to 3D depict alternative arrangements of cut outs that can be used in the proximal portion of the device. They can be applied to any of the embodiments of the insertion device of the present invention but for clarity are depicted without the distal portion.
Figure 3A depicts through holes 22 and 24. Through holes 22 are provided in the proximal portion. Through hole 24 is provided in the intermediate portion, which is hollow. The through holes 22 and 24 reduce the vacuum effect that may make it difficult to remove the insertion device from the surgical instrument.
Figures 3B, 3C and 3D depict alternative arrangements of cut-outs 26, 28, 30 that reduce the vacuum effect. The are all variations on a "T" shape. In the cut-out 26 Figure 3B a large part of the proximal portion has been cut away to form the stem of the "T" and then extended horizontally at the distal end. In the cut-out 28 of Figure 3C a narrower width in the circumferential direction has been cut away from the proximal portion to form the stem of the "T" and then extended horizontally. In the cut-out 30 of Figure 3D, the horizontal extension has been extended further than in the construction of Figure 3C.
The above described embodiments provide an insertion device that is designed to fit a particular surgical instrument. However, there may be more than one size of surgical instrument. For example circular staplers are typically available in two sizes. Although multiple insertion devices for each size of surgical instrument can be provided, it may be desirable to provide a single insertion device that can be used with different sizes of surgical instrument.
Figures 4A, 4B and 5 depict alternative embodiments of the present invention that can be adapted to fit different sizes of surgical instruments. Figures 4A and 4B depict an insertion device 32 in both expanded (Figure 4A) and contracted (Figure 4B) positions, allowing it to fit surgical instruments of different diameters. The insertion device comprises longitudinal members 34 which are made from relatively stiff material. They are joined to adjacent longitudinal members by flexible members 36 that extend along the length of the longitudinal members. The flexible members 36 are more flexible than the longitudinal members 34. Flexible member 36 is narrower at the distal end than the proximal end, so that the longitudinal members can move together and apart from each other to form a cone of different angles. The flexible members 36 fold in contracted positions (Figure 4B) in a similar way to bellows. This enables the longitudinal members 34 to move and define a cone that will enlarge an incision by different amounts, depending on the size of incision required by a particular surgical instrument.
In the embodiment of Figures 4A and 4B, the distal portion is formed by a single loop section 38. The proximal end of the longitudinal members 34 can be attached directly to the surgical instrument or may be extended proximally (not shown).
Figure 5 depicts an alternative insertion device 40 that is the same as figure 4A and 4B except as described below. The longitudinal members 42 of insertion device 40 are joined by a linkage member 44. Linkage member 44 includes a apex which allows the circumferential distance between its ends to vary, thereby altering the separation of the longitudinal members 42. Figure 5 also depicts an extension at the proximal end of the longitudinal members 42. No distal portion is present to open the incision before enlargement in the embodiment of Figure 5, although this may be included in an alternate construction.
Figures 6, 7A and 7B depict alternative embodiments of an insertion system according to the present invention in which an introducer member is used to guide the insertion device to enlarge the incision. The introducer member can provide a more stable guide for the insertion device. It is also advantageous when space inside the body cavity is limited because the insertion device need not include along distal portion, making the overall length shorter.
Figure 6 depicts an insertion system 46 which comprises an introducer member 48 and an insertion device 50. The introducer member 48 is a cylindrical rod. The insertion device 50 is the same as any of the above described embodiments except that the distal portion has been modified to engage the introducer member 48. As the introducer member 48 is a cylindrical rod, the insertion device 50 includes a through hole 52 at its distal end for engaging the introducer member 48. The through hole 52 has a diameter slightly larger than the diameter of the introducer member 48.
An alternative insertion system 54 is depicted in Figure 7A and 7B. This is the same as the insertion system 46 in the embodiment of Figure 6 save as described below. The introducer member 56 is not cylindrical. Instead it has a cross section that defines a longitudinal ridge 57 (visible in the cross section of the introducer member shown in Figure 7B). The distal portion of the insertion device 60 includes a recess that can engage the ridge. As can be seen from the cross section in Figure 7B the ridge 57 is partially cylindrical, including a curved surface that extends through more then 180°. This enables the distal portion of the insertion devce 60 to be clipped into place and remain secure on the introducer member.
Also visible in Figure 7A is the rounded conical end 58 of the introducer member 56. This assists in opening the incision and reduces the chance of damage being caused to internal organs.
Figures 8A to 8C depict the use of the embodiment of Figure 6. First, the introducer member 48 is inserted through the incision into the body cavity. This opens the incision but does not enlarge it. Next, as shown in Figure 8A, the insertion device is attached to the surgical instrument 62 and then slid over the introducer member 48. The insertion device is then slid down the introducer member to enlarge the incision (Figure 8B).
As with the embodiment of Figure 1, the insertion device 50 is maintained in place on the surgical instrument 62 by the insertion force applied by the surgeon against the reaction or frictional force applied by the abdominal wall. Once the insertion device 50 is inside the body cavity the reaction or friction force is removed and the insertion device 50 will naturally tend to fall off the surgical instrument 62 under its own weight (Figure 8C). The introducer member 48 is then removed from the body cavity and the surgical procedure carried out.
At the end of the procedure the surgical instrument is removed from the body cavity. The insertion device is then removed from the body cavity using surgical graspers. Optionally, a length of suture may be tied through the through hole 52 to allow the insertion device 50 to be retrieved by pulling on the suture, in a similar way to the first embodiment described above.
Figure 9 depicts a perspective view of an insertion device 70 according to another embodiment of the present invention. This embodiment is the same as the embodiment of Figure 1, save as described below. In this embodiment an external screw thread 72 is formed on the external surface of the intermediate portion. The screw thread 72 is formed as a ridge following a helical path around the intermediate portion. The screw thread assists the enlargement of the incision because it helps the surgeon impart a rotational component to the insertion force. This provides more control over the enlargement.
Figure 10 depicts a cross section of an insertion device 74 according to still another embodiment of the present invention. This embodiment is the same as the embodiment of Figure 1, save as described below. In this embodiment, the insertion device has a stepped profile so that the enlargement of the incision is carried out in stages. Insertion device 74 of this embodiment includes a cylindrical portion 78 positioned between distal enlargement portion 76 and proximal enlargement portion 80. Both of the distal enlargement portion 76 and proximal enlargement portion 80 have a cross sectional area which increases towards the proximal end. The cylindrical portion 78 has a diameter of 13 mm and a length of mm, although other values can be used in alternate embodiments. In this embodiment the distal and proximal enlargement portions 76, 80 are cone-shaped but other shapes may be used in alternate embodiments. As with the embodiment of Figure 1, proximal portion 82 is for attaching the insertion device to a surgical instrument.
In use, the surgeon can use the cylindrical portion 80 to pause insertion. The length of the cylindrical portion is chosen such that the entire depth of the incision is at the same diameter. This ensures that there is no difference in the enlargement along the depth of the incision and allows a pause during insertion so that the muscle can relax. It is believed that relaxation of the muscle allows further enlargement with reduced risk of tearing.
In alternate embodiments, additional cylindrical portions may be provided to reduce the between additional enlargement portions. This allows more pauses for the muscle to relax between enlargements but is usually less preferable because the length of the insertion device, and hence the space taken up by it inside the body cavity when the surgical instrument is used for a procedure, increases.
It will be appreciated that the different features of the embodiments described above may be combined. For example, the expandable feature and/or the screw thread feature may be combined with the introducer member. Likewise the stepped profile could be applied to the intermediate portion of the Figure 1 embodiment. The stepped profile can also be used in addition to the snout and/or expandable feature and/or the screw thread.