WO2011050387A1

WO2011050387A1 - A minimally invasive surgical technique to retract target issue in a body cavity

Info

Publication number: WO2011050387A1
Application number: PCT/AU2009/001414
Authority: WO
Inventors: Jason Jit-Sun Tan; Naven Chetty
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-10-29
Filing date: 2009-10-29
Publication date: 2011-05-05
Anticipated expiration: 2012-04-29

Abstract

Apparatus (100) for retracting a target (200), such as target tissue in a body cavity (202) accessed by minimally invasive technique is described along with a kit (600) and method (700) for doing the same. The apparatus includes a target-engaging head (102) deliverable into the body cavity through an endoscopic port (210). The target-engaging head (102) is preferably releasably engageable with the target (200). A tether (104) is provided which is attachable (or pre-attached) toward a first end thereof to the target-engaging head (102) and retractable toward a second end thereof through a puncture (204) in the body cavity wall for external fixation. Retracting at least part of the tether (104) through the puncture (204) retracts the engaged target (200) within the body cavity (202). Once retracted, the tether (104) may be anchored externally of the body cavity using anchor means (206) to maintain the target (200) in retraction.

Description

A MINIMALLY INVASIVE SURGICAL TECHNIQUE TO RETRACT TARGET

ISSUE IN A BODY CAVITY

Field of the Invention

The present invention relates to methods and devices for performing surgery. It relates particularly but not exclusively to methods and devices for assisting surgeons during minimally invasive surgery e.g. to retract target tissue during a minimally invasive surgical procedure. The invention also relates to a surgical kit for use during minimally invasive surgery. Background to the Invention

Minimally invasive surgery (MIS), also frequently referred to as keyhole surgery, bandaid surgery and the like, is a surgical technique in which operations are performed using small incisions through which surgical instruments and cameras for visualising the surgical site are inserted. This is in contrast to traditional or open surgery which involves larger incisions through which the surgeon's hands may be passed to access the surgical site. Laparoscopic surgery is one form of MIS performed in the abdomen. By minimising the size of the incisions in MIS, blood loss is reduced as is the risk of infection which generally leads to less pain, reduced hospital stay and generally shorter recovery periods.

Many MIS procedures are now being performed with the use of trocars and cannulas. A trocar is a semi-rigid duct through which surgical instruments are introduced into a body cavity to gain access to the tissue beneath. A piercing tip (obturator) of the trocar is inserted through a cannula or sheath and the cannula partially enters the body cavity through the incision made by the trocar. The obturator can then be removed from the cannula and an elongate endoscope may be inserted through the cannula to view the body cavity. Alternatively/additionally, endoscopic instruments may be inserted through the trocar to perform procedures at the surgical site.

During laparoscopic surgery, it is typical to make 3 or 4 incisions which form laparoscopic port sites used to access the abdomen e.g. for exploratory surgery, removal of an ovary or the like. One incision is required for the endoscopic camera which also illuminates the surgical field. Another incision is required for endoscopic tools manipulated externally of the body cavity to e.g. cut or cauterise tissue. One or two further incisions are required for further endoscopic tools used to manipulate the tissue which obstructs access to the surgical site.

Usually, a surgical assistant (also a physician) assists by manipulating the obstructing tissue. To do this, the assistant uses a grasping instrument inserted through a laparoscopic port site, to grasp the tissue and retract it from the surgical field. The assistant then holds the instrument in position externally, while the surgeon works. While it is necessary to retract obstructing tissue in order to provide clear access to the surgical site, this approach has many drawbacks.

One drawback is that the surgical assistant who holds the instrument retracting the obstructing tissue may cause crowding in the surgical area. This can be hazardous and a source of frustration for the surgical team. Further, even very good surgical assistants are unable to maintain consistently the position of the instrument for prolonged periods so movement of the retracted tissue within the surgical field can occur during the procedure. This can temporarily and unpredictably obstruct access to the surgical site. There is also a cost associated with employing the assistant which ultimately increases the cost of minimally invasive procedures. Furthermore, the need for an extra incision for the retracting endoscopic instrument (grasper) increases the risk of infection and protracted recovery time, while the endoscopic instruments used to retract the obstructive tissue require sterilisation between procedures further driving up costs.

It would be desirable to provide an improved approach to MIS surgery which ameliorates, improves upon or at least provides a viable alternative to the current approaches.

The discussion of the background to the invention included herein including reference to documents, acts, materials, devices, articles and the like is intended to explain the context of the present invention. This is not to be taken as an admission or a suggestion that any of the material referred to was published, known or part of the common general knowledge in Australia as at the priority date of any of the claims.

Summary of the Invention

According to an aspect of the present invention, there is provided apparatus for retracting a target in a body cavity accessed by minimally invasive technique, the apparatus including: a target-engaging head deliverable into the body cavity through an endoscopic port and engageable with the target; and a tether attachable toward a first end thereof to the target- engaging head and at least part of which is retractable toward a second end thereof through a puncture in the body cavity for external fixation; wherein retracting at least part of the tether through the puncture retracts the engaged target within the body cavity.

The tether may be any thin, filamentous extrusion or woven material having sufficient strength to remain in tension while the target tissue is retracted during the surgical procedure. The tether may be manufactured from a range of suitable compositions including e.g. nylon, polypropylene, biocompatible extrudable metals or metal composites to name a few. The target is preferably target tissue in the surgical field which requires manipulation or retraction so as to clear the surgical field and provide improved access to the surgical site. However, the invention may also be used to retract non-tissue targets such as implants or other foreign bodies in the body cavity; clips; surgical instruments; surgical aids and the like.

The target-engaging head is preferably configured to releasably engage the target and may include one or more of e.g. a clamp, a clip, a basket, a net and a loop. The foregoing may be particularly desirable when engaging soft tissue such as the ovaries, bowel and tumours. Alternatively/additionally, the target-engaging head may include one or more of e.g., a screw, an anchor, a barb, and a hook for engaging more robust hard tissues and formations.

In one embodiment, the tether is delivered into the body cavity through an endoscopic port. In this arrangement, the tether may have a degree of inherent rigidity so that the surgeon can controllably deploy the tether through the instrument into the body cavity. Alternatively the tether may be delivered into the body cavity via the puncture through which the tether or part thereof is subsequently retracted and anchored to retract the target.

In a preferred embodiment the tether is deployed into the body cavity, together with a target-engaging head to which it is attached, through an endoscopic port. In such arrangement, the apparatus may also include a substantially rigid shaft which is releasably couplable with the target-engaging head and deployable through the endoscopic port into the body cavity. The rigid shaft assists with location of the target-engaging head near the target and preferably includes an actuator operable externally of the body cavity to control the target-engaging head to engage with the target. In one embodiment, the shaft is releasably couplable with one or more interchangeable target-engaging heads.

The releasable coupling may employ e.g. magnetic, threaded and/or other coupling means. A preferred coupling arrangement also provides means for aligning the target- engaging head and shaft during coupling. The alignment means is particularly useful to guide the two parts during re-coupling of the shaft and target-engaging head prior to removal of the head from the body cavity through an endoscopic port. Preferably, when the target-engaging head and the shaft are coupled together, the head becomes operable from outside the body cavity by use of an actuator such as handles or a trigger operable by the surgeon outside the body cavity.

Preferably, the apparatus includes anchor means such as a clamp, forceps or clip

(e.g. artery clip) for anchoring the retracted part of the tether externally of the body cavity to minimise movement of the target after it is coupled with the target-engaging head. The apparatus may be used with a retraction device insertable through a puncture in the body cavity wall and retracted to a desired position, having a hook, notch or eyelet for grabbing the tether and retracting at least a portion of the tether through the puncture.

According to another aspect of the present invention, there is provided a surgical kit including: one or more tethers and one or more target-engaging heads attachable or pre- attached to a tether and engageable with a target in a body cavity. The one or more target- engaging heads are deployable into the body cavity through an endoscopic port. In use, at least part of a tether engaged with the target is retracted through a puncture in the body cavity wall to retract the target, and is anchorable externally of the body cavity to maintain a retracted position of the target.

In some surgeries, tissue obstructs direct endoscopic access to the surgical site and this tissue is the target. A target-engaging head may include one or more of a clamp, clip, basket, loop, net, screw, anchor, barb, hook or other functional tip configured to engage the target. Preferably, one or more of the target-engaging heads is releasably engageable with the target Typically a target-engaging head is too large to deploy into the body cavity through a mere puncture of around 1 mm through which the tether may be retracted. Thus, a target- engaging head is deployable into (and removable from) the body cavity through an endoscopic port.

In a preferred embodiment, the kit includes at least one substantially rigid shaft which is releasably couplable with a target-engaging head so as to permit interchange between head types. The shaft is deployable into the body cavity through an endoscopic port and assists with locating and engaging the target-engaging head with the target. Once coupled to the target, the target-engaging head is decoupled from the shaft and the shaft is removed from the body cavity through the endoscopic port making the port available for other instruments used by the surgeon.

Any suitable coupling may be provided between the target-engaging heads and the shaft such as e.g. magnetic, threaded or the like. As well as allowing interchange of target- engaging heads on the shaft, the coupling enables a target-engaging head to be re-attached to the shaft so that the head may be removed from the body cavity before the surgery concludes. Preferably, alignment means is provided to assist with alignment of the target- engaging head and the shaft during coupling, particularly when the head is re-coupled to the shaft prior to removal from the body cavity. Prior to removal of the target-engaging head from the body cavity, the tether may be detached or cut from the head and removed from the body cavity e.g. by withdrawal through the puncture. Alternatively, the target-engaging head may be disengaged from the target and the tether and drawn back through the puncture into the body cavity and removed still attached to the target-engaging head through the endoscopic port.

The shaft is deployable into the body cavity through an endoscopic port formed by a trocar, endoscopy catheter, sheath or the like. Preferably, the shaft includes an actuator operable externally of the body cavity by a surgeon. The actuator may be in the form of a trigger, handle or handles operably communicating with a target-engaging head at the other end of the shaft so as to engage the target-engaging head with the target. Where a target-engaging head in the kit does not have a pre-attached tether, a tether in the kit may include a loop toward a first end thereof and a target-engaging head in the kit may include a hook. The tether is attachable to the target-engaging head by engaging the loop and the hook. Alternatively/additionally, a tether in the kit may include a loop at a first end thereof and a target-engaging head in the kit may include an eyelet. The tether is attachable to the target-engaging head by passing the looped end of the tether through the eyelet and passing a portion of the second end of the tether through the loop.

The kit may also provide anchor means such as a clamp or forceps or clip (e.g. artery clip) for anchoring a portion of the tether externally of the body cavity. Anchoring the tether in this way substantially maintains the position of the retracted target e.g. to provide clear access between the surgeon's endoscopic instruments and the surgical site. A tether in the kit may include a substantially rigid portion toward a first end thereof with a loop for coupling with a target in the body cavity. Preferably the loop is adjustable and can be secured or tightened around the target.

According to yet another aspect of the present invention, there is provided a retraction method for use in minimally invasive surgery performed in a body cavity including the steps of: engaging a tether toward a first end thereof with a target in the body cavity; forming a puncture in the body cavity sufficient to retract a length of the tether through the puncture thereby retracting the engaged target within the body cavity; anchoring at least part of the tether externally of the body cavity when the target is in a retracted position; wherein anchoring the tether while the target is in the retracted position improves surgical access.

In one embodiment, the tether is delivered into the body cavity using a needle, catheter or similar such device used to form and/or pass through the puncture. In another embodiment, the tether is attached to a target-engaging head delivered into the body cavity using an endoscopic instrument inserted through an endoscopic port. In such arrangement, it is preferred that the target-engaging head is releasably couplable to a substantially rigid shaft which locates the target-engaging head near the target. The method thus includes engaging the target-engaging head with the target and decoupling the head from the shaft.

The shaft is removed from the endoscopic port making it available for other endoscopic instruments. Prior to concluding the surgery, the tether may be cut from the target-engaging head and withdrawn from the body cavity through the puncture. Alternatively the tether may be removed from the body cavity through the endoscopic port, together with the target-engaging head. The target-engaging head is preferably disengaged from the target and removed from the body cavity e.g. by re-coupling with the shaft re-deployed through an endoscopic port into the cavity. Brief Description of the Drawings

Embodiments of the present invention will now be described in greater detail with reference to the accompanying drawings which are provided by way of non-limiting example. It is to be understood that the particularity of the accompanying drawings does not supersede the generality of the preceding description of the invention.

Figure 1 is a schematic illustration of apparatus for retraction of a target in a body cavity, according to an embodiment of the invention.

Figure 2 is a schematic illustration of the apparatus of Figure 1 together with a substantially rigid shaft coupled with the target-engaging head and actuator means.

Figure 3 is a schematic illustration of the apparatus of Figure 1 in use inside a body cavity to retract target tissue and provide clear access to a surgical site.

Figure 4 shows another embodiment of the invention wherein a looped tether is coupled to target tissue and being retracted through a puncture in the body cavity wall.

Figures 5a to 5c show another embodiment of the invention. In Figure 5a, a target- engaging head is deployed into the body cavity using a shaft inserted through an endoscopic port; a retraction device in the form of a cannula-over needle forms a puncture in the cavity wall. In Figure 5b needle has been removed and a retraction loop is inserted into the cannula; the target-engaging head is directed through the retraction loop and toward the target. In Figure 5c the target-engaging head engages the tissue and is de-coupled from the shaft which has been removed from the endoscopic port; the retraction loop is retracted through the catheter drawing the tether out of the body cavity to retract the engaged target.

Figure 6 is a schematic diagram showing a surgical kit according to an embodiment of the invention.

Figure 7 is a flow chart showing steps in a surgical retraction method according to an embodiment of the present invention.

Figure 8 is a schematic illustration showing a coupling between a shaft and target- engaging head according to an embodiment of the invention.

Detailed description

Referring firstly to Figure 1 there is shown apparatus 100 for retraction of a target in a body cavity accessed by minimally invasive technique such as laparoscopic surgery. The apparatus includes a target-engaging head 102 deliverable into the body cavity through an endoscopic port and engageable with the target. A tether 104 is attachable (or pre-attached) toward a first end thereof to the target-engaging head and at least part of the tether toward a second end thereof is retractable through a puncture in body cavity for external fixation or anchoring (see Figures 3 to 5c). Figure 2 shows the apparatus of Figure 1 , together with a substantially rigid shaft 106 which is coupled with the target-engaging head 102. An example of a coupling is illustrated in Figure 8. Tether 104 extends inside the shaft 106. Also shown in Figure 2 is an actuator 108 in the form of handles which are operably connected to the target-engaging head 102 when coupled to the rigid shaft. The handles are manipulated by a surgeon externally of the body cavity to control operation of the target-engaging head e.g. by opening and closing jaws of target-engaging head 102 to engage or disengage the target. Coupling the target-engaging head 102 with the shaft 106 renders the target-engaging head controllable from outside the body cavity. This may involve a mechanism which, upon rotation of the shaft about its elongate axis in a clockwise direction opens the jaws and when rotated counter-clockwise, closes the jaws.

Figure 3 shows the apparatus of Figure 1 in use inside a body cavity 202. In this arrangement, the rigid shaft 106 has been inserted through a trocar 210 to deploy the target- engaging head 102 into the body cavity 202. Actuator handles 108 are operated to engage the target-engaging head with target tissue 200. Figure 3 shows puncture 204 through which a portion of the tether 104 is withdrawn to retract the engaged target 200. The retracted tether is anchored in place by anchor means 206 in the form of a clamp.

The puncture is a small (e.g. 1 mm) opening formed in the body cavity wall 208 using any suitable instrument. In one embodiment, a simple suture needle is used. In another embodiment a device such as an Endo Close™ is used, in which a spring-loaded blunt stylet having a notched end is used to capture and retract the tether. The stylet contains a needle which can be pushed through and puncture the body cavity wall. In another embodiment, an intravenous cannula-over-needle is utilised. The needle punctures the body cavity wall, the cannula is positioned across the wall and the needle is removed from the cannula which remains in situ providing a channel through which a retraction device such as a hook or needle may be deployed to grab and retract the tether. The portion of the tether which extends outside the body cavity when retracted is anchored in place by anchor means 206 in the form of a clip (e.g. an artery clip).

The target tissue 200 shown in Figure 3 represents a tissue obstruction which obstructs access to the surgical site beneath to which the surgeon requires access. The present invention may be used to manipulate any target in the abdomen such as part of the bowel or ovary, or hard tissues, tumours and the like. The target-engaging head used to engage the target is selected according to the nature of the target. Accordingly, for engaging an ovary or the bowel an atraumatic head would be employed (e.g. basket, net, loop) where as a hook, anchor or corkscrew head may be used to engage hard tissue or non-tissue targets by penetrating the target. Referring now to Figure 4, there is shown another embodiment of the invention wherein a looped tether 104 is coupled to target tissue 200 inside body cavity 202. The tether may include a substantially rigid portion toward a first end thereof which is ejected from a substantially rigid shaft 106 and guided over the target tissue 200. The loop portion is adjustable and tightened securely over the target tissue 200. Prior to engaging the looped tether with the target tissue, the tether may be passed through an eye 304 of retraction device 302. The retraction device may also provide a puncturing tip for forming a puncture in the body cavity wall as shown in Figure 4 (Figures 5a-c show an alternative retraction device and method). The retraction device is then withdrawn from puncture 204 drawing with it a portion of the tether 104 and retracting the engaged target 200 which may then be anchored in position using anchor means 206 (Figure 3) externally of the body cavity.

Figure 5a shows a target-engaging head 102 coupled to substantially rigid shaft 106 deployed into body cavity 202 through trocar 210. The target-engaging head is attached to a tether (not shown) which extends inside the shaft. Prior to engaging the target-engaging head with the target (tissue), puncture 204 is formed by retraction device 302 comprising a cannula 302a over a needle 302b having a sharp tip which forms a puncture 204 in the body cavity wall 208 through which cannula 302a passes. When the cannula tip is located inside the body cavity the needle is withdrawn from the cannula remains in situ, the hollow interior of which provides a small channel across the body cavity wall (see Figure 5c).

Figure 5b shows cannula 302a in situ with a loop 312 being inserted by the surgeon.

The loop passes through cannula 302a into body cavity 202 where it forms an eye 314. Target engaging head 102 is passed through the eye 314, directed by rigid shaft 106 deployed through trocar 210 and the head is located proximal to the target 200. Now turning to Figure 5c, the target-engaging head 102 engages with the target 200 by operation of the actuator (not shown) and the shaft 106 is decoupled from the target-engaging head and withdrawn from trocar 210 making the trocar available for other endoscopic instruments required for the surgery. Tether 104 may remain inside trocar 210 or it may be drawn through the trocar into the body cavity and subsequently retracted through puncture 204 to retract the target 200. In the embodiment illustrated in Figure 5c, the tether is retracted by withdrawing loop 312 in direction W. Retraction of 2 to 3 cm may be achieved by retracting the tether 104 2 to 3 cm outside the cavity prior to anchoring.

Should other targets require manipulation or retraction during the procedure, the same cannula 302a may be utilised to withdraw a second or further tethers and they may be anchored outside the body using a single anchor means 206 in the form of a clamp or clip or multiple anchor means if they require separate anchoring and/or control. Once the shaft has been withdrawn from the endoscopic port formed by trocar 210 it is available for other endoscopic instruments and the target 200 remains retracted from the surgical field providing clear access to the surgical site.

Preferably, the devices used to perform the inventive method are provided in sterile kit form such as that shown in Figure 6. The kit 600 includes one or more tethers 104 which may be provided in sterile packaging. The tethers are engageable either directly (e.g. via a loop) or indirectly (via a target-engaging head) with a target such as a target tissue in the body cavity. Other targets may be retracted, such as implants or foreign bodies (stents, bands, clamps and the like) in the surgical field. A tether in the kit may include a substantially rigid portion containing a loop toward a first end of the tether, as has been described in connection with Figure 4.

The kit also includes one or more target-engaging heads 102 which are releasably couplable with a substantially rigid shaft 106 which may also be provided in the kit. A target- engaging head may include one or more of e.g. a screw portion A (e.g. corkscrew) a hook B, jaws C, basket D or any other engaging element such as a clamp, clip, barb, anchor or the like for engaging the target. The target-engaging heads (e.g. heads C and D) may come pre-attached to tethers 104a. Alternatively, they may be attachable by knotting or looping the first end of a tether onto a hook or eyelet provided on a target-engaging head.

Typically, the target-engaging heads are deployable into the body cavity through an endoscopic port and, in the embodiment illustrated, the target-engaging heads are releasably couplable with internal end I of a shaft 106 which may also be provided in the kit. In an embodiment the kit also includes an actuator 108 shown in the form of handles connectable to an external end E of rigid shaft 106.

Preferably, the target-engaging heads are interchangeable and adapted to engage with the rigid shaft by a coupling. An embodiment of a coupling 1 10 is illustrated in Figure 8. Shaft 106 has a magnetic tip 802a on the interior end I which is attracted to corresponding magnetic 802b on the target-engaging head 102. Magnetic tip 802a includes a hex-shaped socket 812 which receives a corresponding hex-shaped protrusion 810 on the target- engaging head. Magnetic coupling exploits attractive forces between end I of shaft 106 and the target-engaging head help to guide the two parts together, as well as maintain coupling. The corresponding hex-shaped protrusion 810 and socket 812 into which the protrusion cooperates assists with alignment during coupling, particularly when the target-engaging head is being re-coupled onto the shaft prior to removal of the head from the body cavity. Alternate alignment means may include e.g. two or more protrusions on one of the target- engaging head (on its shaft-coupling end) and end I of shaft 106 which, when brought into an abutment, align with corresponding grooves in the other of end I of shaft 106 and the target- engaging head (on its shaft-coupling end). Alternatively, a web, tongue and groove or other coupling arrangement, as may be known in the art, may be used to couple and/or align the target-engaging head and the shaft.

Preferably, the target-engaging heads are releasably engageable with the target so they can be removed from the body cavity when retraction of the target is no longer required although it is contemplated that absorbable target-engaging heads and absorbable tethers may be utilised. These absorbable components dissolve in the body over time and do not, therefore, require removal from the body cavity.

The kit 600 may also include a retraction device 302 for retracting a portion of tether out of a puncture formed in the body cavity wall although there are many approaches that may be adopted for this purpose. In one embodiment the retraction device also creates the puncture and thus has a tip which is sufficiently sharp to puncture the body cavity wall, although a separate skin needle could be used for this purpose. Preferably the retraction device includes a hook, notch or eyelet for grabbing the tether. A hooked/notched retraction device may be deployed into the body cavity with or without a cannula. In one preferred embodiment, a cannula-over-needle of the type commonly used in intravenous catheterisation may be used to puncture the body cavity wall and form a percutaneous channel into the body cavity by removing the needle and leaving the cannula in situ. A retraction loop may be inserted through the cannula for engaging and retracting the tether, as described with reference to Figures 5a-c.

Anchor means 206 may also be provided with the kit although a range of readily available surgical devices (such as artery clips and forceps) may be used to anchor the tether in a retracted state.

Now referring to Figure 7, there is shown a flow chart for performing a retraction method 700 according to an embodiment of the invention. According to the inventive method, a target in a body cavity can be manipulated by, in a step 702, coupling a tether towards its first end with the target within the body cavity. In a step 704 a puncture is formed in the body cavity and a length of the tether is withdrawn through the puncture in a step 706 in order to manipulate the target within the body cavity, e.g. to retract target tissue which is obstructing MIS access to a surgical site. When the target has been retracted into the required position the withdrawn portion of the tether is anchored externally of the body cavity in a step 708 clearing the surgical field and providing access to the surgical site enabling the surgery to be performed (710). Prior to concluding the surgery, the tether is separated from the target tissue in a step 712, e.g. by cutting the tether or disengaging it from the tissue and the tether is removed from the body cavity, preferably by withdrawing it through the puncture in a step 714. The surgery may then be concluded (step 716).

The tether may be delivered into the body cavity using a needle which is used to perform the puncture. Alternatively, the tether may be delivered into the body cavity using the substantially rigid shaft as shown in Figures 2, 4, 5a-c and 6, which is deployed into the body cavity through an endoscopic port. In this embodiment, the tether is pre-attached to a target- engaging head which is used to engage the tether and the target. Once engaged with the target, the target-engaging head is decoupled from the shaft and the shaft is removed from the body cavity freeing up the endoscopic port for other instruments which are required for performing the surgery. The tether is withdrawn through a small puncture as described previously, obviating the need for a further endoscopic port which, in prior art approaches, has been required to maintain the position of the target tissue when grasped by an endoscopic instrument and retracted from the surgical field.

While the embodiments exemplified herein are directed to laparoscopic surgery performed in the abdomen, it is to be understood that the apparatus, method and kit described herein also has applicability in other minimally invasive surgery approaches performed in the thorax, pelvis or spine. It may also be used in other minimally invasive surgeries e.g. as performed in the joints. Indeed, the present invention may also have utility in open surgery approaches where obstructive tissue must be retracted to clear the surgical field.

Advantageously, the present invention provides a technique and devices where one or more than one obstructive tissue or tissue region or other target can be retracted from the surgical site by use of a simple and very small diameter tether. More than one tether can be retracted through a single puncture which makes the inventive approach more attractive than the existing approach which necessitates a separate endoscopic port and instrument for each retraction. Given that the puncture site formed to retract the target is small (e.g. in the order of 1 or 2 mm) the location and orientation of retraction may be altered by forming a new puncture and repositioning and retracting the tether to achieve a desired vector of movement/retraction of the engaged target.

In addition, since no assistant is required to maintain the target in the retracted position, once the anchor means is in place externally to the body cavity, the patient can be sent for imaging, or moved with the target maintained in the retracted position but without the need for an assistant holding a retracting instrument. This reduces costs and also reduces risks to the patient and surgical staff. Moreover, since only a very small puncture (e.g. 1 to 2 mm) is required to retract the target, in most cases no stiches are required to close the puncture sites and healing may be achieved after application of a simple sterile dressing.

It is to be understood that various modifications, additions and/or alterations may be made to the parts previously described without departing from the ambit of the present invention as defined in the claims appended hereto.

Claims

The claims defining the invention are as follows:

1 Apparatus for retracting a target in a body cavity accessed by minimally invasive technique, the apparatus including:

a. a target-engaging head deliverable into the body cavity through an endoscopic port and engageable with the target; and

b. a tether attachable toward a first end thereof to the target-engaging head and retractable toward a second end thereof through a puncture formed in the body cavity wall for external fixation;

wherein in use, retracting at least part of the tether through the puncture retracts the engaged target within the body cavity.

2 Apparatus according to claim 1 wherein the tether is deliverable to the body cavity through an endoscopic port.

3 Apparatus according to any one of the preceding claims further including a substantially rigid shaft releasably couplable with the target-engaging head and deployable through an endoscopic port.

4 Apparatus according to claim 3 wherein the shaft includes an actuator operable externally of the body cavity such that when the shaft and target-engaging head are coupled the target-engaging head is controllable from outside the body cavity.

5 Apparatus according to claim 3 or claim 4 including a magnetic coupling between the target-engaging head and the shaft.

6 Apparatus according to any one of claims 3 to 5 including alignment means for aligning the target-engaging head and the shaft for coupling.

7, Apparatus according to any one of the preceding claims further including anchor means for anchoring the retracted part of the tether externally of the body cavity.

8 A surgical kit including:

a. one or more tethers; b. one or more target-engaging heads attachable or pre-attached to a tether and engageable with a target in a body cavity, said one or more target-engaging heads deployable into the body cavity through an endoscopic port.

wherein in use, at least part of a tether engaged with the target is retracted through a puncture in the body cavity wall to retract the target and is anchorable externally of the body cavity to maintain a retracted position of the target.

9. A surgical kit according to claim 8 wherein one or more of the target-engaging heads is releasably engageable with the target.

10. A surgical kit according to claim 8 or claim 9 further including a substantially rigid shaft releasably couplable with a target-engaging head in the kit and deployable through an endoscopic port.

1 1 . A surgical kit according to claim 10 wherein the one or more target-engaging heads is interchangeable on the substantially rigid shaft.

12. A surgical kit according to claim 10 or claim 1 1 further including an actuator operable externally of the body cavity to control a target-engaging head when coupled with the shaft to engage the target.

13. A surgical kit according to any one of claims 10 to 12 wherein the one or more target- engaging heads and the shaft include a magnetic coupling.

14. A surgical kit according to any one of claims 10 to 13 wherein the one or more target- engaging heads and the shaft include alignment means for aligning a head and shaft for coupling.

15. A surgical kit according to any one of claims 8 to 14 further including anchor means for anchoring a portion of the tether externally of the body cavity to maintain the position of the retracted target.

16. A surgical kit according to any one of claims 8 to 15 wherein the one or more target- engaging heads includes target-engaging means selected from the group including: a clamp, a clip, a basket, a loop, a net, a screw, an anchor, a barb, and a hook.

17. A surgical kit according to any one of claims 8 to 16 further including a retraction device adapted to retract at least a portion of a tether through the puncture to retract the target within the body cavity, the retraction device having one or more of a hook, notch or eyelet for grabbing the tether and withdrawing at least a portion of the tether through the puncture.

18. A surgical kit according to any one of claims 8 to 17 wherein a tether in the kit includes a stiffened portion forming a loop for coupling with a target in a body cavity.

19. A surgical kit according to any one of claims 8 to 18 wherein a tether in the kit includes a loop toward a first end thereof and a target-engaging head in the kit includes a hook; wherein the tether is attachable to the target-engaging head by engaging the loop and the hook.

20. A surgical kit according to any one of claims 8 to 18 wherein a tether in the kit includes a loop at a first end thereof and a target-engaging head in the kit includes an eyelet; wherein the tether is attachable to the target-engaging head by:

a. passing the looped end through the eyelet; and

b. passing a portion of the second end of the tether through the loop.

21 . A retraction method for use in minimally invasive surgery performed in a body cavity including the steps of:

a. engaging a tether toward a first end thereof with a target in the body cavity;

b. forming a puncture in the body cavity sufficient to retract a length of the tether through the puncture thereby retracting the engaged target within the body cavity; and

anchoring at least part of the tether externally of the body cavity when the target is in a retracted position.

22. A retraction method according to claim 21 including delivering the tether into the body cavity using an endoscopic instrument.

23. A retraction method according to claim 21 including delivering the tether into the body cavity using a needle used to perform the puncture.

24. A retraction method according to any one of claims 21 to 23 including the step of removing the tether from the body cavity by withdrawing through the puncture.

25. A retraction method according to any one of claims 21 to 24 wherein the tether is attached to a target-engaging head which is releasably coupled to a substantially rigid shaft, and the method includes the steps of:

a. engaging the target-engaging head with the target; and

b. decoupling the target-engaging head from the shaft.

26. A retraction method according to claim 26 including the steps of:

prior to concluding the surgery:

a. cutting the tether from the target-engaging head and withdrawing the tether through the puncture; and

b. disengaging the target-engaging head from the target and removing the target- engaging head from the body cavity through an endoscopic port.