The invention relates to a grasper comprising at least two movable parts embodying a jaw, wherein each of the movable parts is mounted on at least one support, wherein a relative position of the movable parts with respect to each other is variable by changing the relative position of the supports with respect to each other.

US 3,527,492 discloses a trash pickup device wherein a shaft has at its outer circumference outer spring members affixed thereto, which are further affixed at a far end of the shaft to inner spring members that have a common and movable operating rod within the shaft. At the far end of the sheath the outer spring members and inner spring members both connect to cups which serve as grasping tools.

A grasper according to the preamble is further known from US2012/0239080. This document discloses two merged laparoscopic graspers, having one external sheath, one handle, two pairs of jaws, two actuating rods, and two controls. As a re- suit a dual grasper is provided and the surgeon making use of it may use two instruments in one hand facilitating for instance intra-corporeal knot tying, at the expense however of a complicated and costly design.

It is one of the objectives of the invention to pro- vide a less complicated and less costly design that still enables the surgeon to attune the instrument to his particular needs during surgery, and to provide such an instrument with different modalities of use, making the surgeon's life during surgery easier with associated less risk for the patient.

The grasper of the invention is provided with one or more of the features according to the appended claims.

In a first aspect of the invention the grasper comprises an outer sheath wherein all supports of the movable parts are movable into and out of said sheath, wherein the outer sheath is longitudinally movable along all supports of the two movable parts between two positions, a first position in which the supports of the two movable parts are moved out of said sheath and released from restriction imposed by the outer sheath and in which the relative position of the two movable parts is determined only by the relative position of the supports, and a second position in which all supports of the two movable parts are moved into the sheath so as to restrict the relative position of said supports and to arrange that the position of the two movable parts is determined by the outer sheath only. In this way the grasper of the invention has two modalities of use, notably a first modality in which 'fine' grasping is enabled and a second modality in which 'coarse' grasping is enabled. Fine grasping which can be understood as delicately grasping is enabled by retraction of the outer sheath so as to have the relative position of the two movable parts of the jaw determined exclusively by the relative position of the supports. Coarse or firm grasping is enabled by moving the outer sheath forward and having it re- strict the relative position of the two movable parts of the jaw therewith overruling the control of the jaw's two movable parts by the relative position of the supports of the two mov ^¬ able parts.

It is remarked that WO95/09566 teaches a hingeless grasping tool having two movable parts forming a jaw that are mounted on a single and shared support. An outer sheath is ap ^¬ plied to engage the two movable parts of the jaw so as to control movement of the two movable parts with respect to each other so as to control opening and closing of the jaw.

WO95/09566 does however not teach dual grasping modalities distinguishing between delicate grasping and firm grasping.

In a beneficial design of the grasper of the invention each movable part is mounted on at least two supports. The movement of each movable part can then be determined by each of such two supports alone or in combination. It may further be beneficial that the supports of the movable parts comprise flexural members so as to arrange that a force applied by the supports to the movable parts is limited to a value defined by mechanical properties of the flexural members.

The invention will hereinafter be further elucidated with reference to the drawing of an exemplary embodiment of a grasper according to the invention that is not limiting as to the appended claims .

In the drawing: - figures 1A, IB and 1C show the grasper of the invention in an embodiment wherein the outer sheath is retracted; and

- figures 2A, 2B and 2C show the grasper of the in- vention of the embodiment shown in figures 1A, IB and 1C wherein the outer sheath restricts the movement of the two movable members of the jaw.

Whenever in the figures the same reference numerals are applied, these numerals refer to the same parts.

Making reference first to figure 1A, IB and 1C the grasper of the invention is indicated with reference 1. The grasper 1 comprises two movable parts 4, 5 defining a jaw 2. The movable part 4 is mounted in this exemplary embodiment on cooperating supports 6, 6' , whereas the movable part 5 is mounted on cooperating supports 7, 1' . Instead of mounting each movable parts on two cooperating supports it is also possible to mount each movable part on a single support which is dedicated to the concerning movable part.

Opposite to the jaw 2 is the proximal side 3 of the grasper 1 at which side the grasper is controlled. At this proximal side 3 an outer sheath 8 is provided which for clarity purposes is shown in figures 1A, IB and 1C in dotted lines. In said figures 1A, IB and 1C the outer sheath 8 is in a position in which the two movable parts 4, 5 of the jaw 2 are re- leased from restriction by the outer sheath 8 so as to enable that the relative position of the movable parts 4, 5 is exclusively determined by the relative position of the supports 6, 6' and 7, 7' .

Operation of the grasper 1 with the outer sheath 8 in the retracted position is as follows. Movement of movable part 4 can be done by changing the relative position of the supports 6, 6' of movable part 4 with respect to each other.

Movement of movable part 5 can be done by changing the relative position of the supports 7, 7' of movable part 5 with re- spect to each other.

In figure 1A the movable parts 4, 5 of the jaw 2 are moved concertedly by movement of the central supports 6' and 1' whilst the outer supports 6 and 7 remain stationary. In figure IB an alternative is shown in which the movable parts outer supports 6 and 7 whilst the central supports 6' and V remain stationary.

In all situations shown in figures 1A, IB and 1C the outer sheath 8 is kept in a first position in which all supports 6, 6 ^r 1, 1' of the two movable parts 4, 5 that are movable into and out of said sheath 8 are moved out of said sheath 8 and released from any restriction imposed by the outer sheath 8 so that the relative position of the two movable parts 4, 5 is determined by the relative position of the supports 6, 6'; 1, 1' only. This corresponds to fine or delicate grasping .

In figures 2A, 2B and 2C the outer sheath 8 is moved forward to engage the outer supports 6, 7 of the movable parts 4, 5 of the jaw 2. Correspondingly all supports 6, 6'; 7, 7' of the two movable parts 4, 5 are moved into the sheath 8 so as to restrict movement of said supports 6, 6'; 7, 1' to arrange that the position of the movable parts 4, 5 is deter ^¬ mined by the outer sheath (8) only so that control of the opening and closing of the jaw 2 is done by positioning and moving the outer sheath 8 back-and-forth . This corresponds to coarse or firm grasping.

It is remarked that the supports 6, 6' and 1, 1' of the movable parts 4, 5 preferably comprise or are embodied as flexural members. One of the advantages of arranging that the supports 6, 6' and 7, 1' of the movable parts 4, 5 comprise or are embodied as flexural members is that a force applied by the supports 6, 6' and 7, 1' to the movable parts 4, 5 is limited to a well-defined pre-established value which is deter- mined by properly selecting the mechanical properties of the flexural members. It will be clear that this only applies when the outer sheath 8 is in the retracted position, and the position of the movable parts 4, 5 is only determined by their supports 6, 6' and 7, Ί' .

Although the invention has been discussed in the foregoing with reference to an exemplary embodiment of the grasper of the invention, the invention is not restricted to this particular embodiment which can be varied in many ways without departing from the gist of the invention. The dis- cussed exemplary embodiment shall therefore not be used to construe the appended claims strictly in accordance therewith. On the contrary the embodiment is merely intended to explain the wording of the appended claims without intent to limit the claims to this exemplary embodiment. The scope of protection of the invention shall therefore be construed in accordance with the appended claims only, wherein a possible ambiguity in the wording of the claims shall be resolved using this exem ^¬ plary embodiment.