Lockable arm for medical device

Abstract

The invention relates to a medical device, for example for surgery or examination, said medical device comprising at least two segments and at least one joint having at least one degree of freedom, wherein the two segments are connected to each other via said joint, such that the two segments are moveable with respect to each other, wherein the joint comprises a locking means arranged to be adjustable between a first state in which the locking means lock the joint and thereby the segments in a certain position and / or orientation with respect to each other and a second state in which the locking means unlock the joint, such that in the second state the segments are able to move with respect to each other. The invention also relates to a medical system comprising such a medical device.

Description

[0001] LOCKABLE ARM FOR MEDICAL DEVICE

[0002] The invention relates to a medical device, for example for surgery or examination, said medical device comprising at least two segments and at least one joint having at least one degree of freedom, wherein the two segments are connected to each other via said joint, such that the two segments are moveable with respect to each other, wherein the joint comprises a locking means arranged to be adjustable between a first state in which the locking means lock the joint and thereby the segments in a certain position and / or orientation with respect to each other and a second state in which the locking means unlockthe joint, such that in the second state the segments are able to move with respect to each other.

[0003] The medical device may in particular be an invasive medical device, i.e. a device that is intended to be inserted into a human or animal body.

[0004] The medical device provides the advantage of allowing the at least one joint to be in the second, flexible state, such that the position and / or orientation of the segments with respect to each other and thereby the shape of the medical device may be adjusted such that it may be inserted into the human or animal body without harming any tissue or organs and / or may be located close to a point of interest, e.g. where surgery or examination is needed. When the two segments have a desired position and / or orientation with respect to each other the at least one joint can be locked, such that the segments that are connected to each other via that locked joint are in a fixed position and / or orientation with respect to each other.

[0005] That the segments are able to move with respect to each other in the second state may alternatively be rephrased as that in the second state the segments are allowed to change position and / or orientation with respect to each other.

[0006] Dependent on the type of joint used, which may be any desired and / or suitable type of joint, the segments may be moveably with respect to each other in at least one and preferably two or three planes and / or about at least one and preferably two or three axes.

[0007] In an embodiment of the medical device accordingto the invention the locking means are made of or comprise a variable stiffness material, for example a shape memory polymer, that is adjustable between the first state in which the variable stiffness material is relatively stiff and thereby locks the joint and the second state in which the variable stiffness material is relatively flexible and thereby unlocks the joint.

[0008] As a result of the variable stiffness material being relatively stiff in the first state it is able to lock the joint in the first state, and as a result of the variable stiffness material being relatively flexible in the second state it is able to unlock the joint in the second state.

[0009] Relatively stiff and flexible may at least be understood with respect to the two states, i.e. the variable stiffness material is stiffer in the first state than in the second state. For example, the variable stiffness material may be at least five times stiffer in the first state than in the second state.

[0010] An advantage of a shape memory polymer as the variable stiffness material is that it may return to it original shape upon activation by a suitable stimulus and if no external force is exerted on the segments.

[0011] The locking means may be adjustable between the first state and the second state by means of any suitable stimulus, such as heating and / or cooling, light, stress, or a chemical stimulus. A suitable source for any such stimulus may be provided, which source may either be part of the medical device or may be an external and / or remote source.

[0012] In an embodiment of the medical device accordingto the invention the locking means are adjustable between the first state and the second state by means of heating and / or cooling, optionally wherein the device comprises at least one heating and / or cooling element for heating and / or cooling the locking means.

[0013] Heating and / or cooling is currently seen as a preferred way of adjustingthe locking means between the first state and the second state. However, as noted above, othersuitable stimuli may be applied.

[0014] The optionally provided at least one heating and / or cooling element provides active heating and / or cooling of the locking means for adjusting the locking means from the first state to the second state or vice versa. Additionally or alternatively an external heating and / or cooling source may be provided.

[0015] Preferably at least one such active heating and / or cooling element is provided, either for adjusting the locking means from the first state to the second state, or from the second state to the first state. Practically heating will adjust the locking means from the first state to the second state and cooling will adjust the locking means from the second state to the first state. Adjusting the locking means to the reversed state may occur passively. For example, a heating element may be provided for adjusting the locking means from the first state to the second state, and passive cooling may be used for adjusting the locking means from the second state to the first state. Similarly, a cooling element may be provided for adjusting the locking means from the second state to the first state, and passive heating may be used for adjusting the locking means from the first state to the second state. Such passive cooling or heating provides the advantage that no active cooling or heating element has to be provided therefor, therefore allowing the medical device to be simpler and / or smaller and / or lighter and / or cheaper. However, passive heating or cooling may take more time than active heating or cooling, so it may alternatively be possible to provide a second heating or cooling element for adjustingthe locking means to the reversed state. In other words, a heating element may be provided for adjusting the locking means from the first state to the second state and a cooling element may be provided for adjusting the locking means form the second state to the first state. Alternatively one element may be provided that is arranged for heating and cooling. The temperature used for heating or cooling may be chosen in dependence of the type of variable stiffness material used and may in particular be chosen around the transition or glass temperature of the variable stiffness material.

[0016] The heating and / or cooling element may be any suitable type of heating or cooling element, such as an electric heating or cooling element, more in particular for example a wire, strip or inductive heating or cooling element.

[0017] In an embodiment of the medical device according to the invention the at least one heating and / or cooling element is provided and is embedded into the locking means.

[0018] Embedding the at least one heating and / or cooling element in the locking means provides the advantage of efficient heat transfer from the heating and / or cooling element to the locking means. An alternative or additional advantage is that by embedding the heating or cooling element in the locking means the heating or cooling element is isolated from the surroundings, such that the heating and / or cooling element does not heat or cool the human or animal body, or at least only in a limited way.

[0019] Embedded may mean that the locking means at least partially and preferably fully enclose the heating and / or cooling element. Wires or other connections for activating the heating and / or cooling element may protrude from the locking means and may be connected to a power source.

[0020] The locking means comprising the at least one heating and / or cooling element embedded therein may be made in any suitable way. For example, the locking means may comprise at least two layers between which the heating or cooling element is sandwiched. Alternatively the locking means and heating or cooling element embedded therein may be made usingfor example 3D printing.

[0021] In an embodiment of the medical device accordingto the invention the locking means comprise at least one compliant element that connects the two segments to each other, wherein the compliant element is adjustable between the first state in which the compliant element is relatively stiff and locks the segments in said certain position and / or orientation with respect to each other and the second state in which the compliant element is relatively flexible, thereby allowing the segments to move with respect to each other.

[0022] The compliant element provides flexibility to the joint in the second state thereof and thereby allows for movement of the segments in the second state. In the first state the stiffness of the compliant element prevents movement of the segments and thereby locks the segments.

[0023] Such compliant element preferably comprises the variable stiffness material as described above.

[0024] The above described at least one heating or cooling element may be embedded in the compliant element. The compliant element may directly connect the two segments to each other, i.e. without any intermediate parts or elements, or may indirectly connect the two segments together, e.g. via one or more intermediate parts or elements.

[0025] In an embodiment of the medical device accordin to the invention the locking means of said joint comprise at least two of said compliant elements, wherein the compliant elements are individually adjustable.

[0026] An advantage of this embodiment is that this may allow for more accurate control of the movement of the segments connected to each other via the joint comprising said at least two individually adjustable compliant elements.

[0027] Practically each compliant element may be arranged such that it allows movement in a certain plane and / or about a certain axis in the second state, i.e. each compliant element may provide one degree of freedom. If at least two such compliant elements are provided, the compliant elements may allow movement in different planes and / or about different axis. If such two compliant elements are individually adjustable the joint may be controlled to be moveable in a desired plane and / or about a desired axis by adjusting the compliant element that allows movement in the desired plane and / or about the desired axis to the second state and by having the other compliant element in the first state, or in multiple planes and / or about multiple axes by adjusting multiple compliant elements at the same time.

[0028] In an embodiment of the medical device accordingto the invention the joint comprises an intermediate element, for example a substantially cross-shaped intermediate element, arranged between the two segments, and wherein a first compliant element of the at least two compliant elements is connected to the intermediate element with one end thereof and connected to a first segment of the two segments with the second end thereof, and wherein a second compliant element of the at least two compliant elements is connected to the intermediate element with one end thereof and connected to the second segment of the two segments with the second end thereof.

[0029] In such an embodiment the two segments are connected to each other via the intermediate element and at least two compliant elements. The intermediate element and the at least two compliant elements allow for the segments to be moveable with respect to each other with at least one degree of freedom, preferably two degrees of freedom.

[0030] In an embodiment of the medical device accordingto the invention the compliant element provides a rolling contact between the segment and intermediate element.

[0031] This may for example be achieved by the compliant element being provided between the segment and intermediate element.

[0032] In an embodiment of the medical device accordingto the invention the two segments define or comprise at least one yoke of the joint.

[0033] Practically the at least one and preferably at least two compliant elements are connected to the yoke(s). The compliant element may in particular extend between the yoke and the intermediate element.

[0034] In an embodiment of the medical device accordingto the invention the compliant elements are substantially S- or Z-shaped, wherein a central part of the substantially S- or Z-shaped compliant element extends between the intermediate element and the yoke of the segment.

[0035] The central part may provide a rolling contact extends between the intermediate element and the yoke of the segment.

[0036] The two ends of the substantially S- or Z-shaped compliant elements may respectively be attached to the intermediate element and the yoke.

[0037] Such compliant element may allow the segments to be moved or bent in the length direction of the S- or Z-shaped compliant element. In an embodiment of the medical device according to the invention the device comprises actuating means or actuatable means for actuating at least one of the segments to move in a certain direction with respect to the other segment in the second state of the locking means.

[0038] Such actuating means may for example comprise a tendon-drive or any other suitable actuation means.

[0039] The actuatable means may be any suitable actuatable means.

[0040] Preferably the actuatable means comprise a magnet, even more preferably a permanent magnet.

[0041] Such a magnet may be controlled by a remote actuator, such that the device itself does not require means for actuating the actuatable means. This allows the device to be smaller, and in particular allows a smaller cross-sectional size, which is especially convenient for an invasive medical device.

[0042] In an embodiment of the medical device according to the invention the device comprises a plurality of pairs of segments, wherein the segments of each pair are connected to each other via a respective joint, and the pairs of segments together define a row, wherein the actuatable means are provided at or near a segment located at a free end of the row.

[0043] An advantage of such embodiment is that the movement of all segments being connected to an unlocked joint, i.e. a joint in the second state, can be controlled by providing the actuatable means, for example the magnet, at the end of the row.

[0044] The invention also relates to a medical system, said system comprising a medical device as described above or below, having any one or more of the above or below described features, alone or in anysuitable combination, and further comprising a remote actuator for actuating the actuatable means at a distance from the actuatable means.

[0045] As described above, an advantage of such an embodiment is that the remote actuator allows the medical device itself to be smaller. Preferably the actuator comprise a source for creating a magnetic field and wherein the actuatable means can be actuated by controlling a direction and / or magnitude of the magnetic field.

[0046] In such an embodiment the actuatable means comprise said above described magnet.

[0047] The system may further optionally comprise a stimulus source, which source is for example a heat and / or cooling source, a light source, a stress source or a chemical source.

[0048] The invention will be further elucidated with reference to the attached figures, in which:

[0049] Fig. 1 is a schematic perspective view of a medical device according to a first embodiment of the invention;

[0050] Figs. 2A and 2B show two joints segments connected via a joint of figure 1 in more detail, wherein figure 2A is a schematic perspective view en figure 2B is an schematic exploded view;

[0051] Fig. 3 shows a compliant element as used in the joint of figure 1 in more detail in a schematic perspective view;

[0052] Fig. 4 is a schematic cross-sectional view through a segment of the device of figure 1 ;

[0053] Figs. 5A and 5B show a schematic perspective view of two segments and a joint accordingto a second embodiment, wherein figure 5A shows the two segments in line and figure 5B shows the segments bend with respect to each other;

[0054] Figs. 6A and 6B show a schematic perspective view of two segments and a joint according to a third embodiment, wherein figure 6A shows the two segments in line and figure 6B shows the segments bend with respect to each other;

[0055] In the figures same elements are denoted by same reference numbers.

[0056] The figures show a medical device 1 or details or parts thereof. The medical device 1 is in particular an invasive medical device, meaning that it can be inserted into a human or animal body. The medical device 1 may for example be used for surgery or examination. It is noted that the surgical instrument or camera is not shown in the figures, because these are well known in the prior art. The invention relates to how the shape of such a medical device may be adjusted such that it may be inserted into the human or animal body without harming any tissue or organs and / or may be located close to a point of interest, i.e. where surgery or examination is needed, and may be locked in a fixed shape when a desired shape of the medical device is obtained, and this adjustment and locking is explained by means of the figures.

[0057] Figure 1 shows an exemplary embodiment of the medical device 1 . In this exemplary embodiment the medical device 1 comprises in total four segments 2. It will be clear forthe skilled person that the medical device 1 may comprise any desired number of segments 2 with a lower limit of two. By increasing the number of segments the flexibility of the shape and / or the length of the medical device 1 may be increased. Each pair of two segments 2 is connected to each other via a respective joint 3, such that in this embodiment three joints 3 are provided, because the four segments 2 define in total three pairs of segments. The three joints 3 are in this embodiment individually controllable between a first state in which a said joint 3 is locked, thereby locking the segments 2 connected to each other via such locked joint 3 in a certain position and / or orientation with respect to each other, and a second state in which a said joint 3 is unlocked, thereby allowingthe segments 2 connected to each other via such unlocked joint 3 to move with respect to each other. In this embodiment each joint 3 allows for movement of the two segments 3 in two planes, but it will be clear for the skilled person that any suitable and / or desired type of joint may be provided, allowing the segments to be moved in any desired amount of planes out of a maximum of three planes and / or about any desired amount of axes out of a maximum of three axes. As will be clear from figure 1 , the three joints 3 allow the medical device 1 to adopt a rather complex, desired shape.

[0058] The locking and unlocking of a said joint 3 will now be described in further detail with respect to figures 2A, 2B and 3, which show an exemplary embodiment of the joint 3 and segments 2. These figures show that in this embodiment each joint 3 comprises in total four compliant elements 4 that connect the two segments 2 to each other. Each compliant element 4 comprises a variable stiffness material, in this embodiment a shape memory polymer, wherein the variable stiffness material and thereby the compliant element 4 is adjustable between a first state in which the variable stiffness material and thereby the compliant element 4 is relatively stiff and a second state in which the variable stiffness material and thereby the compliant element 4 is relatively flexible. Because the variable stiffness material and thereby the compliant element 4 is relatively stiff in the first state thereof, the compliant element 4 does not bend in the first state, at least not under forces exerted on the joint 3 and segments 2 in use of the device 1 , such that the compliant element 4 locks the joint 3. In the flexible second state the compliant element 4 is bendable, such that it allows movement of the segments 2 with respect to each other. The four compliant elements 4 of this exemplary embodiment are substantially S- or Z-shaped and connect the two segments 2 to each other via an crossshaped intermediate element 5 and via yokes 6 of the segments 2. In particular, two of the four compliant elements 4 are connected to yokes 6 of one of the two segments 2 with one end thereof and to the cross-shaped intermediate element 5 with the other end thereof. The other two compliant elements 4 out of the four compliant elements 4 are connected to the yokes 6 of the other segment 2 with one end thereof and to the crossshaped intermediate element 5 with the other end thereof. For example, as is best visible in figures 2A and 2B, compliant elements 4a are connected to yokes 6 of the lower segment 2 and to the intermediate element 5, in particular to bars of the crossshaped element 5. Compliant elements 4b are connected to yokes 6 of the upper segment 2 and to the intermediate element 5. As is best visible in figure 2A, the compliant elements 4, in particular a central part thereof, is present between the yokes 6 and intermediate element 5, such that it allows a rolling contact between the yokes 6 and intermediate element 5 in the second state of the compliant element 4. The compliant elements 4a together with the yokes 6 of the lower segment 2 and intermediate element 5 allow the segments 2 to move in a first plane. The compliant elements 4b together with the yokes 6 of the upper segment 2 and intermediate element

[0059] 5 allow the segments 2 to move in a second, orthogonal plane. The compliant elements 4a, 4b are in this embodiment individually adjustable and are preferably adjusted in pairs, i.e. the compliant elements 4a are adjusted together and the compliant elements 4b are adjusted together, such that it can be controlled in which of the two planes the segments 2 are moveable. If the compliant elements 4a are in the second state and the compliant elements 4b are in the first state, the segments 2 are moveable in the first plane only. If the compliant elements 4b are in the second state and the compliant elements 4a are in the first state, the segments 2 are moveable in the second plane only. If all compliant elements 4a, 4b are in the second state the segments 2 are moveable in both planes. If all compliant elements 4a, 4b are in the first state the segments 2 the joint is completely locked and the segments are not moveable, at least not under pressures exerted on the segments 2 in use of the device 1 . The planes in which the segments are moveable extend in the length direction of the compliant elements 4. It is noted that by providing two compliant elements 4a that work in pairs with pairs of yokes

[0060] 6 of the lower segment 2 and two compliant elements 4b that work in pairs with pairs of yokes 6 of the upper segment 2, a relatively stable movement of the segments in the first and / or second plane may be provided. The pairs of yokes 6 of one segment are located at opposite angular positions of that segment 2. The pairs of yokes 6 of the two connected segments 2 are at an angular distance of 90 degrees with respect to each other.

[0061] Figure 3 shows a compliant element 4 in more detail. In this exemplary embodiment of the compliant element 4 the compliant element 4 comprises two layers or sheets 7 of variable stiffness material that extend in the length direction L of the compliant element 4 and between which an electrical heating element 8 is embedded or sandwiched. Contacts 9 of the electrical heating element protrude or extend out of the compliant element 4 and are connected to a power source of the device 1 (not shown in the figures). By activating the electrical heatingto heat the compliant element 4 the variable stiffness material will transfer to the second, flexible state thereof. In this embodiment no cooling element is provided, the compliant element 4 will transfer back to the first state as a result of passive cooling. In alternative embodiments a cooling element may be provided instead of a heating element, or both a cooling and heating element may be provided. Figure 4 shows a transverse cross section of one of the segments 2. This view shows that the segments 2 comprise a circumferential or cylindrical wall 12. Within the cylindrical wall 12 the segments 2 may be hollow or filled with a filling material, such as PMMA. A central channel 10 runs or extends through the intermediate element 5 and segments 2 in the length direction thereof, see also figure 2B. Between the intermediate element 5, yokes 6 and compliant elements 4 space is left free, thereby defining four further channels 11 that extend in the length direction of the device 1 through the segments 2. These channels 10, 11 allows for wires or other desired elements to run through the medical device 1 . For example, wires, cables or other elements for connecting the heating element 8 to the power source may extend through the channels 11 . For example, wires, cables or other elements of the camera or surgery tool may extend through the channel 10.

[0062] With reference to figure 1 , the device 1 may further comprise a permanent magnet 13. The magnet 13 allows for the device 1 to be actuated in movement by an external actuator (not shown). The external actuator may create a magnetic field, wherein the direction and magnitude of the magnetic field is adjustable. By adjusting the direction and magnitude of the magnetic field the magnet 13 is steerable in a certain direction and the segments 2 that connect to unlocked joint(s) 3, i.e. joint(s) 3 in the second state, will thereby be moved. Segments of locked joint(s) 3 will not move. The magnetic field is maintained until the joint(s) 3 are transferred back to the first state and are thereby locked. This step may be repeated for other or same joint(s) 3.

[0063] It is noted that instead of an actuatable means such as the magnet 13 the device 1 may comprise actuating means, such as a tendon-drive.

[0064] Figures 5A and 5B show a schematic perspective view of a medical device 1 comprising in this second embodiment two segments 2 and a joint 3 that is in this second embodiment defined by the compliant element 4, i.e. the joint 3 is the compliant element 4. The compliant element 4 is in this embodiment directly attached to the two segments 2, without any intermediate element. The segments 2 have rounded parts between which the compliant element 4 is present and provides a rolling contact. In the second state the segments 2 of this embodiment are moveable or bendable in one plane that extends in the length direction of the compliant element 4, as will be clear from figure 5B. The segments 2 are shown to have one rounded end, but alternatively these may have rounded ends at both ends, such that these may connect to further segments 2 via further compliant elements 4. It is noted that the segments 2 of this embodiment are embodied as yokes. Instead, the parts that are shown in figures 5A and 5B by reference number 2 may be yokes that are part of segments in a similar manner as shown in the first embodiment of figures 1 - 4. In the latter case each segment, for example each cylindrical segment, may for example comprise two or four of such yokes that are located at different angular positions of the cylindrical segment 2. The yokes of a next segment 2 may be located at the same angular positions and thereby aligned and the compliant element 4 may connect to those yokes and extend between the rounded ends of those yokes as shown in figures 5A and 5B.

[0065] Other features of the device 1 of figures 5A and 5B will not be repeated here and will be apparent from figures 1 -4 and the description thereof.

[0066] Figures 6A and 6B show a schematic perspective view of a medical device 1 comprising in this third embodiment two segments 2 and a joint 3 that is in this second embodiment defined by the compliant element 4, i.e. the joint 3 is the compliant element 4. The compliant element 4 is in this embodiment directly attached to the two segments 2, without any intermediate element. In this embodiment the compliant element 4 does not provide a rolling contact, but allows to be bent in the length direction thereof and therefore allows the segments 2 to be bent with respect to each other, as is shown in figure 6B. It is noted that also in this embodiment the segments 2 of this embodiment are embodied as yokes, but in a similar manner as the second embodiment the elements denoted by reference number 2 may be yokes of a segment 2, for example a cylindrical segment as shown in the first embodiment of figures 1 -4.

[0067] It is noted that the compliant elements 4 of the third embodiment may alternatively have a substantially cylindrical shape, thereby allowing movement of the segments 2 in any direction.

[0068] Other features of the device 1 of figures 6A and 6B will not be repeated here and will be apparent from figures 1 -4 and the description thereof.

[0069] It will be apparent from the above figures that the segments 2 and joint 3 may be embodied in any suitable way and may have one or more degrees of freedom.

[0070] Although the invention is elucidated above on the basis of a number of specific examples and embodiments, the invention is not limited thereto. Consequently, the scope of the invention is defined by the following claims.

Claims

Claims1 . Medical device, for example for surgery or examination, said medical device comprising at least two segments and at least one joint having at least one degree of freedom, wherein the two segments are connected to each other via said joint, such that the two segments are moveable with respect to each other, wherein the joint comprises a locking means arranged to be adjustable between a first state in which the locking means lock the joint and thereby the segments in a certain position and / or orientation with respect to each other and a second state in which the locking means unlock the joint, such that in the second state the segments are able to move with respect to each other.

2. Medical device accordin to claim 1 , wherein the locking means are made of or comprise a variable stiffness material, for example a shape memory polymer, that is adjustable between the first state in which the variable stiffness material is relatively stiff and thereby locks the joint and the second state in which the variable stiffness material is relatively flexible and thereby unlocks the joint.

3. Medical device according to claim 1 or 2, wherein the locking means are adjustable between the first state and the second state by means of heating and / or cooling, optionally wherein the device comprises at least one heating and / or cooling element for heating and / or cooling the locking means.

4. Medical device accordingto claim 3, wherein the at least one heating and / or cooling element is provided and is embedded into the locking means.

5. Medical device accordingto any of the preceding claims, wherein the locking means comprise at least one compliant element that connects the two segments to each other, wherein the compliant element is adjustable between the first state in which the compliant element is relatively stiff and locks the segments in said certain position and / or orientation with respect to each other and the second state in which the compliant element is relatively flexible, thereby allowing the segments to move with respect to each other.

6. Medical device according to claim 5, wherein the locking means of said joint comprise at least two of said compliant elements, wherein the compliant elements are individually adjustable.

7. Medical device according to claim 5 or 6, wherein the joint comprises an intermediate element, for example a substantially cross-shaped intermediate element, arranged between the two segments, and wherein a first compliant element of the at least twocompliant elements is connected to the intermediate element with one end thereof and connected to a first segment of the two segments with a second end thereof, and wherein a second compliant element of the at least two compliant elements is connected to the intermediate element with one end thereof and connected to the second segment of the two segments with a second end thereof.

8. Medical device accordingto claim 7, wherein the compliant element provides a rolling contact between the segment and intermediate element.

9. Medical device according to any of the preceding claims, wherein the two segments define or comprise at least one yoke of the joint.

10. Medical device accordingto any of the preceding claims, comprising actuating means or actuatable means for actuating at least one of the segments to move in a certain direction with respect to the other segment in the unlocked state of the locking means.

11. Medical device accordin to claim 10, wherein the actuating means comprise a tendon-drive or wherein the actuatable means comprise a magnet, preferably a permanent magnet.

12. Medical device according to claim 10 or 11 , comprising a plurality of pairs of segments, wherein the segments of each pair are connected to each other via a respective joint, and the pairs of segments together define a row, wherein the actuatable means are provided at or near a segment located at a free end of the row.

13. Medical system, said system comprising a medical device accordingto any of claims 10 - 12, and further comprising a remote actuator for actuating the actuatable means at a distance from the actuatable means.

14. Medical system accordingto claim 13, wherein the actuator comprises a source for creating a magnetic field and wherein the actuatable means can be actuated by controlling a direction and / or magnitude of the magnetic field.

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