WO2000062689A1

WO2000062689A1 - A trocar with expandable point

Info

Publication number: WO2000062689A1
Application number: PCT/DK2000/000196
Authority: WO
Inventors: Therkel BISGÅRD
Original assignee: Bisgaard Therkel
Priority date: 1999-04-21
Filing date: 2000-04-18
Publication date: 2000-10-26
Also published as: DK199900539A; AU3958600A

Abstract

The invention concerns a trocar with expandable point. The trocar comprises mutually sliding outer and inner tubes. The point of the inner tube may be slid forward in relation to the point of the outer tube. The point of the inner tube is provided with slits so that flaps are formed. When the inner tube is retracted in relation to the outer tube, the flaps are folded together while overcoming an elastic force in the material which the inner tube is made of. When the inner tube is advanced forward in relation to the outer tube, the flaps will be automatically unfolded due to the elastic force and form a collar having a lateral dimension which is greater than a forward dimension.

Description

A TROCAR WITH EXPANDABLE POINT

Background of the Invention

The present invention concerns a trocar with expandable point as stated in the pream- ble of claim 1.

WO 98/03121 describes a trocar intended for forming abutment with the inner side of a wall of a body part. The trocar has a point consisting of a number of flaps. The flaps are mounted by means of hinges on a flange so that the flaps may be folded up and unfolded, respectively, in relation to the flange. In the folded state the flaps are capable of being inserted through a hole in the wall on the body part. Subsequently, the flaps may be unfolded in order to form abutment on the wall for the trocar.

This trocar implies several drawbacks. First, it has appeared that by using hinges for mounting the flaps to the flange there is a great risk that body fluids and remains from the wall of the body part after penetrating through may prevent that the flaps may be unfolded. Second, it is necessary to have means that may extend through the flange for unfolding the flaps from the folded-up state. Third, no means for holding the flaps in the unfolded state have been provided, and this implies risk of the flaps unintention- ally being folded up again after having been unfolded.

US 5,707,359 describes a trocar with an expandable point, and where the expandable point is intended for forming a funnel for catching bodies like gallstones from a gall bladder or the like from other body cavities. The trocar has an inner tube which is sliding in an outer tube, and where the inner tube is provided with fingers between which are fastened a flexible membrane so that a funnel is formed. The funnel is designed so that the forward dimension is substantially greater than the lateral dimension in order thereby to project far into the body cavity and for holding fast the bodies caught in the membrane when the expandable point is folded up.

As mentioned, this trocar has the purpose of forming a funnel for catching foreign bodies in body cavities. It is not possible to maintain a given protrusion in relation to the body cavity of the point of the trocar, but it is neither necessary with the indicated purpose of the trocar. For the same reason, the trocar cannot be used as a hole of passage for surgical instruments like scissors, files, or the like for performing surgery in the body cavity. Finally, the trocar is only usable in larger body cavities due to the relatively great lateral dimension and even greater forward dimension.

A trocar with expandable point is also known from US patent no. 5,279,564. This trocar comprises an outer tube in which there is disposed a smaller syringe. The inner syringe is provided with spring-biased elements 12 that subsequent to insertion the syringe through a cavity may be brought into abutment on a body wall via a spring loading, as they will be expanded so that they have a greater diameter than the diameter of the outer tube. In order to establish a lenient abutment against the body wall, there are provided cylindric segments 22 at the ends of the separate, spring-biased elements 12, and which 22 are arranged for distributing the pressure load exerted on the body wall.

A trocar described in the US patent is complicated to produce as it comprises several elements to be mutually connected. Furthermore, during the insertion there will be a risk that spring elements normally held in recesses 16 may be displaced out of the re- cesses and be disposed in the interspace between the outer tube and the syringe so that advancing of the syringe will be impeded.

The object of the present invention is to provide a very simple trocar which in a secure way may be inserted into a body cavity and be held in contact with a wall for the body cavity and where it is quick, easy and secure to slide forward the point of the trocar for expanding the point, for holding the point in its expanded state and for subsequently retracting the point again and withdrawing the trocar from of the cavity.

This object is achieved with a trocar which is peculiar in that the point of the inner tube is provided with a number of slits extending longitudinally of the inner tube, that the point of the inner tube thus consists of a number of flaps, that at least the flaps are made of flexible material, that the flaps in a folded state are elastically prestressed and that the elastic prestressing is released when the flaps are in an unfolded state so that the flaps are unfolded in a protruding position and form a collar consisting of the flaps and interspaces formed between the flaps, and that in the protruding position the lateral extension of the collar is greater that the forward extension of the collar.

A trocar with these characteristics is capable of creating a sufficient contact with an inner side of the body part. Simultaneously, the trocar according to the invention ensures good access for surgical instruments passed through the trocar as the forward dimension is very limited. Insertion into and withdrawal from the body part of the trocar takes place easily and quickly in that the flaps forming the collar may be folded up just by pulling the inner tube, and will be unfolded when the inner tube is slid forward relatively to the outer tube.

Furthermore, the trocar according to the invention can be produced in a very simple way as it only consists of an outer tube and an inner tube. Instead of providing abutment on the inner side of the body wall by separate elastic elements, the flaps formed at the end of the inner tube are used in an advantageous way. As there are only two elements to perform the mutual displacing there is no risk of they being wedged to each other as would be the case if the contact means were provided in the shape of separate means provided between the inner and the outer tube.

By making at least the flaps, but preferably all of the inner tube, of an elastic material, it is possible to avoid special solutions for establishing expansion of the point of the inner tube. This occurs automatically when the inner tube is displaced forward relative to the outer tube. The elastic material will preferably be a suitable type of plastic, but may also be a suitable type of metal. The elasticity has to be relatively high as the flaps have to be unfolded so much that the collar formed by the flaps have a lateral dimension which is greater than the forward dimension.

Brief description of the drawing

The invention will now be described in more detail with reference to the accompanying drawing, where Fig. 1 is a section through a trocar according to the invention with an inner tube in retracted position, Fig. 2 is a section through a trocar according to the invention with an inner tube in protruding position, Figs. 3 A and 3B are side views of a way of holding the inner tube in retracted and in protruding position, respectively, in relation to the outer tube, and Fig. 4 is a perspective view of a trocar according to the invention with the inner tube in the protruding position.

Fig. 1 shows a trocar with an outer tube 1 and an inner tube 2. The outer tube 1 is cylindric in the shown embodiment and has an outer diameter D and an inner diameter d. The inner tube 2 is situated inside the outer tube 1 , and the inner tube 2 is likewise cylindric with an outer diameter E just less that the inner diameter d of the outer tube and an inner diameter e. The inner tube 2 has a thickness t.

The outer tube 1 has a point 3 intended for being passed through the wall 5 of an outer or inner body part, e.g. through a muscle, through a joint-capsule, through the abdominal wall or through walls to other body cavities. Before the point 3 of the outer tube 1 is passed through the wall 5 of the body part, there is initially established a hole 6 through the wall. Alternatively, the outer tube 1 may be provided with a sharp point, possibly arrow-shaped, so that the trocar itself may establish the hole by displacing the outer tube through the wall. When the outer tube 1 is passed through the wall 5, the inner tube 2 situated inside the outer tube 1 is similarly passed through the wall 5.

In the embodiment shown, the inner tube 2 is situated in retracted position. The inner tube has a point 4 provided with slits 7, and between the slits 7 flaps 8 are formed. The slits 7 are formed just by performing cutting up of the point 4 of the inner tube 2 in direction parallel with the longitudinal axis L of the trocar. The flaps have a length 1. The inner tube 2 are made of an elastic material. In a protruding position of the inner tube 2 relative to the outer tube 1 (see Fig. 2), it is possible for the flaps 8 to extend laterally outwards relative to the longitudinal axis L. Fig. 2 shows the trocar with the inner tube 2 displaced forward as shown with the arrow directed to the left to a protruding position. The point 4 of the inner tube 2 extends past the point 3 of the outer tube 1. The flaps 8 at the point 4 of the inner tube 2 extend forward and outward in relation to the longitudinal axis L. The flaps 8 extend forward the distance a and laterally the distance A. The distance A is greater than the distance a. It is illustrated how the point 3 of the outer tube 1 is passed through the hole 6 in the wall 5 and into a cavity 10 on a body part. Furthermore, it is illustrated how an outer side 9 of the flaps 8 are in contact with an inner side 11 of the wall 5 of the body part.

Thereby it is possible to hold the trocar in accurate position relative to the wall as it is possible to draw the whole trocar backwards relative to the wall. Hereby the outer side 9 of the flaps 8 will come into contact with the inner side 11 of the wall 5, and thereby the trocar may be withdrawn no further. Then it is possible to pass surgical instru- ments (not shown) for surgery through the inner tube 2 of the trocar and into the cavity

10.

A displacement forward or backward of the surgical instrument (not shown) relative to the trocar, will imply a completely corresponding displacing of the instrument in rela- tion to the wall as the trocar is completely secured relative to the wall when the flaps are in contact with the wall. Since in the protruding position the flaps extend relatively much laterally as compared with forward direction, there will be created good accessibility for instruments intended for surgical intervention. In particular, with the instrument it will be possible to reach out to the sides as the forward extension of the flaps is considerably less than the lateral extension. The instrument may be passed very far to the side in the cavity in immediate vicinity of the wall of the body part. If the trocar is simultaneously pulled back as shown with the arrow pointing to the right, the distance between the point of the trocar and e.g. the underlying cartilage in a joint or other internal body parts to be treated surgically is increased.

When the surgical intervention in the cavity 10 is finished, the instrument may be taken out. Hereafter it is possible to retract the inner tube 2 in relation to the outer tube 1 whereby the point 4 of the inner tube will be withdrawn past the point 3 of the outer tube 1, and the flaps 8 will be folded up and into the outer tube 1 (see Fig. 1). Then the trocar may be taken out of the cavity 10 through the hole 6 in the wall 5.

The flaps 8 have an elasticity being sufficiently low that the flaps 8 may be folded up when the inner tube 2 is withdrawn relative to the outer tube 1, but which is sufficiently great after all that it can hold the trocar inside the cavity 10 even though the trocar is drawn back relative to the wall 5.

Figs. 3 A and 3B show a mechanism for holding fast the inner tube 2 and the outer tube 1 in a mutual desired position. The mechanism consists of a first sleeve 12 fastened around an end 13 of the outer tube 1 which is opposite to the point 3 (not shown), and a second sleeve 14 fastened to an end 15 of the inner tube 2 opposite to the point 4 (not shown).

The first sleeve 12 has a contact surface 16 forming an angle α with the common longitudinal axis L for the outer tube 1 and the inner tube 2. In the illustration shown the contact surface slopes from a forward point 17 to the rear toward the end 13 of the outer tube 1 and downward to a rear point 18. The other sleeve 14 has a contact sur- face 19 which likewise forms an angle α with the longitudinal axis L. In the embodiment shown, the contact surface 19 slopes from a forward point 20 to the rear toward the end 15 of the inner tube 2 and downward to a rear point 21.

The view in Fig. 3A is the position taken by the sleeves and the respective contact surfaces when the inner tube is in its protruding position relative to the outer sleeve.

The view in Fig. 3B is the position to be taken by the first sleeve 12 and the second sleeve 14 and the respective contact surfaces 16,19 when the inner tube 2 is in its retracted position relative to the outer tube 1. Shifting between one position and the other occurs by rotating the inner tube 2 and the second sleeve 14 which is fastened to the inner tube 2 one half turn about the longitudinal axis L simultaneously with displacement occurring in rearward or forward direction. Fig. 4 is a perspective view of a trocar. In the view shown, the inner tube 2 is in the protruding position. The flaps 8 extend forward and laterally relative to the point 3 of the outer tube 1 and thus form the collar intended for bearing against the inner side of the wall of the body part (see Fig. 2). In the illustration shown there are six flaps 8 formed by six slits 7. In other embodiments it will be possible to provide more or less flaps by forming more or less slits. The flaps may have a length between 1 mm and 50 mm, preferably about 10 mm.

The inner tube is preferably made of plastic with sufficiently elasticity in order to se- cure a certain large strength in the collar when the inner tube is in its protruding position and a sufficiently small strength for the flaps to be folded up when the inner tube is drawn back in relation to the outer tube, the inner tube may be made of POM, nylon or other kind of plastic, and the outer tube may be made of a corresponding type or other, more stiff kind of plastic, or may be made of stainless steel or other metal.

The invention is described in the above with reference to outlined sketches of the invention. It will be possible to made a trocar with other relative diameters and other lengths. Trocars with other cross sections than circular, e.g. square, triangular, oval etc., are possible to make. The outer tube and the inner tube may be made of either plastic or metal, or each of a combination of these materials. In the opposite end of the point of the inner tube and the outer tube it will be possible to provide the outer tube and the inner tube with various other means than described for mutually sliding the two tubes and/or for passing surgical instruments into and out of the trocar.

Claims

1. A trocar with expandable point, said trocar comprising an outer tube for inserting a point of the trocar into a body cavity, and in which tube there is accommodated an inner tube for advancing relative to the outer tube so that a point of the inner tube in an advanced position protrudes in relation to a point of the outer tube, that the point in a retracted position has a first outer circumference being lesser that an inner circumference of the outer tube surrounding the inner tube, and that the point in an advanced position has a second outer circumference which is greater than the first outer circum- ference, and where the point of the inner tube in the protruding position extends forwards of the point of the inner tube and laterally outward in relation to a longitudinal axis of the tubes, characterised in that the point of the inner tube is provided with a number of slits extending longitudinally of the inner tube, that the point of the inner tube thus consists of a number of flaps, that at least the flaps are made of flexible ma- terial, that the flaps in a folded state are elastically prestressed and that the elastic pre- stressing is released when the flaps are in an unfolded state so that the flaps are unfolded in a protruding position and form a collar consisting of the flaps and interspaces formed between the flaps, and that in the protruding position the lateral extension of the collar is greater that the forward extension of the collar.

2. A trocar according to claim 1, characterised in that the flaps have an abutting surface for the collar consisting of an outer side of the flaps, and that the flaps in the advanced position extend in a downward and outward curve so that the abutting surface is concave.

3. A trocar according to claim 1 or 2, characterised in that the flaps have a length between 1 and 50 mm, preferably between 2 and 20 mm, and that in the protruding position, the collar has a lateral dimension between 5 and 100 mm and a forward dimension between 1 and 50 mm.

4. A trocar according to any preceding claim, characterised in that the inner tube is made of a flexible plastic material, that the outer tube surrounds the inner tube and has an internal diameter between < ??? > mm and < ??? > mm, that the inner tube is circular, alternatively oval, and has an outer circumference equal to the inner diameter of the outer tube, and that the inner tube has an inner diameter between 0.5 and 2 mm.

5. A trocar according to any preceding claim, characterised in that the point of the inner tube is provided with between 2 and 20 flaps, preferably between 4 and 12 flaps, more preferably provided with 6 flaps.

6. A trocar according to any preceding claim, characterised the inner tube is made of plastic, preferably made of POM, and that the outer tube is made of plastic, alternatively made of metal.