SURGICAL FORCEPS

Abstract: The present invention relates to a surgical instrument for providing clamping action around an object, comprising a first leg (1) and a second leg (2) which are articulated to each other by means of a pivot (9). The first (1) and the second (2) legs each have a gripping portion (3) and a clamping portion (4), and at least one hook means (5, 6). The hook means (5) of the first leg (1) is further engageable with the hook means (6) of the second leg (2) to establish temporary locking of the clamping portions of the legs at a certain minimum distance from each other. The hook means (5) of the first leg (1) comprises a turnable means (5) having at least one thread with a pitch to allow, by turning of the means, stepless fine adjustment of the distance between the clamping portions (4) of the legs (1, 2).

Description: SURGICAL FORCEPS Technical Field The present invention relates to a surgical instrument for providing clamping action around an object, comprising a first leg and a second leg which are ar- ticulated to each other by means of a pivot, which have a gripping portion and a clamping portion and which each have at least one hook means, the hook means of the first leg being engageable with the hook means of the second leg to establish temporary locking of the clamping por- tions of the legs at a certain minimum distance from each other and thus static but adjustable clamping action around the object. Background of the Invention Instruments for clamping together blood vessels, so- called vascular clamps, are used in surgical operations with a view to temporarily stopping the blood flow in a blood vessel . This type of instrument has been used in surgery since the beginning of the 20 th century, and the locking device of traditional vascular clamps comprises a hook device on each leg, one leg often having only one hook which can engage one of several hooks on the other leg to lock the jaws or clamping portions of the legs at a certain minimum distance from each other. The legs are thus lockable stepwise in relation to each other. However, such a locking device suffers from the drawback that the hooks are usually widely spaced apart, which means that the degree of clamping of the blood vessel can only be adjusted fairly roughly. Therefore, there is a risk that the clamping will be either too loose, so that the blood flow is not stopped, or too tight, so that the blood vessel is injured. In addition, when applying the vascular clamp the clamping portions of the legs must normally first be brought together more closely, resulting in a higher clamping pressure than is necessary to stop the blood flow, and then be able to be somewhat moved apart when hooks, one on each leg, have passed each other and can engage. Also such initial excessive clamping may cause injuries to a blood vessel. Blood vessel injuries may cause complications. On the one hand, there is a risk of thrombosis in the injured part, in which case the blood vessel is obstructed, and, on the other, there may occur so-called excessive healing in the injured part, i.e. the tissue grows and gets thicker than normal, resulting in the blood vessel getting narrow and maybe obstructed. Summary of the Invention One object of the present invention is thus to obviate the drawbacks and problems of prior-art technique and to provide a surgical instrument for clamping blood vessels, which makes it possible to rapidly and step- lessly clamp together to a desired degree a blood vessel in one simple operation and with precision to stop the blood flow, without causing any injuries to the blood vessel. It is also an object of the invention to provide a surgical instrument which is simple and cheap to manufacture. At least these objects are achieved by means of a surgical instrument according to claim 1. The invention is thus based on the understanding that, by designing the hook means of one of the legs as a turnable means having a thread in which the hook means of the other leg can run, a stepless adjustment of the distance between the legs is allowed by turning or screwing the thread means. When clamping, for instance, a blood vessel, the clamping portions of the legs are brought together from each side of the blood vessel and applied to the same with a desired clamping pressure which is preferably less than the final pressure. In this connection, the hook means of the second leg is hooked on the hook means of the first leg to lock the legs in relation to each other in a first rough adjustment, after which the thread means is turned until a desired distance is obtained between the clamping portions of the legs and thus a desired clamping pressure against the blood vessel or some other object which is to be clamped. It is important to the function of the invention that the thread has a pitch so that its distance from the leg on which it is arranged is changed when turning the thread means. This may be provided in a number of different ways. In a preferred embodiment, the thread is helical and arranged on one side of a thread means which is turnably mounted on the first leg. In a preferred embodiment, the thread means is plate-shaped, but can also be formed in other ways, for instance, as an elongated cylinder having the thread arranged on one end surface . Furthermore, the thread means is preferably circular, but can also be, for instance, rectangular or octagonal. In a preferred embodiment, the thread is concentric with the turning centre of the thread means. The thread can, however, also be arranged in other ways. It may, for instance, have the form of a plurality of closed, circular threads which are eccentrically arranged about the turning centre of the thread means, thus obtaining an ascending pitch on one half of the circumference of the threads and a descending pitch on the other side. The thread could also be helical and arranged on the circumferential surface of a roll or cylinder which is turnably mounted on the first leg. In a preferred embodiment, the hook means of the second leg comprises one or more projecting portions which are cam- shaped or toothed. The portion or the por- tions preferably have a certain extent in the longitudinal direction, but can, for instance, comprise a part which is tapered or pointed in cross-section and whose pointed end is arranged to engage with and run in the thread. One projecting portion of the hook means is enough for the instrument to be adjustable in a stepless manner, but several cam portions facilitate a first rough adjustment of the instrument before the turning of the thread means begins . In a preferred embodiment, the cam-shaped portion or portions are pointed in cross-section, but they can, of course, also have another shape, for instance, be provided with a plane top, such as that of a buttress thread or a square thread. In addition, in a preferred embodiment that flank of each cam-shaped portion which is oriented in the direction opposite to the direction of mo- tion when clamping is substantially perpendicular to or makes an angle which is less than 90° with the plane of motion of the legs. Similarly, in a preferred embodiment the inner flank of the helical thread, i.e. the flank facing the turning centre of the thread, is substantially perpendicular to or makes an angle which is less than 90° with the plane of motion of the legs. If the instrument is held so that the plane of motion of the legs is horizontal, said flanks are thus substantially vertical or make an angle with the horizontal plane, which is less than 90°. By forming the flanks of the thread and the cam- shaped portions, respectively, in the above-mentioned manner, a satisfactory engagement is obtained between the flank surfaces of the cam portion and the thread, respec- tively, and the gripping portions of the legs are prevented from moving away from each other, perpendicularly to the plane of turning or motion, when they are engaged. The hook means of the legs must thus be "lifted out" of each other to be able to move freely in the release di- rection. The cam-shaped portions do not, of course, have to have plane flanks. The portions may, for instance, have cross-sectional profiles which are similar to that of round threads, i.e. rounded flanks having rounded tops. Certain shapes of the flanks do not, however, pro- vide sufficient blocking effect preventing the gripping portions of the legs from moving apart, perpendicularly to the plane of turning or motion, when they are engaged, and therefore the instrument may in such cases be equipped with some form of locking device which is not showed in more detail and which locks the hook means in engagement with each other. Moreover, in a preferred embodiment the helical thread is pointed in cross-section. It goes without saying that the cross-section could have another shape just like the cam- shaped portions, for instance, like that of a buttress thread. Summarising, there are thus a number of variants of the design of the thread and the cam portions, respectively. The cross-sectional profiles may, for instance, have the shape of a V-thread, a buttress thread, a square thread or a round thread. When using the instrument, the gripping portions of the legs are moved in the clamping direction so that their respective hook means engage each other. The instrument is, preferably, adjusted stepwise in a first, roughly adjusted position by making the thread of the thread means gradually engage successive cam portions. Then the thread means is turned so that the legs continue to move in the clamping direction until the blood flow in the blood vessel has been stopped. It is, however, perfectly possible to operate the instrument in such manner that the hook means of the respective legs is moved "in the air", parallel to the other hook means, without any contact with each other, and that the legs are not brought together and do not hook on to each other until a desired rough adjustment of the clamping portions has been obtained. Subsequently, the fine adjustment takes place by the thread means being turned until the blood flow is stopped, as previously described. When releasing the legs to remove the instrument from the blood vessel, the legs are displaced a distance from each other in the direction transversely of the plane of motion so that the hook means disengage and then the legs can be pivoted in the release direction. In the preferred embodiment of the invention, the legs are articulated to each other substantially at the middle of their longitudinal extent, their gripping portions on one side of the pivot and their clamping por- tions on the other side. It would, however, be feasible to design the instrument so that the legs are articulated at one of their ends, the gripping portions and the clamping portions thus being located on the same side of the pivot . Other possible fields of application of the invention, besides clamping blood vessels, could, for instance, be clamping intestines or regulating the flow in elastic hoses in a stepless manner. Brief Description of the Drawing In the drawing FIG 1 shows the surgical instrument according to a preferred embodiment of the invention, the arrows indicating the movements of the legs and the thread means when releasing the instrument, FIG 2 shows the surgical instrument according to a preferred embodiment of the invention, the arrows indicating the movements of the legs and the thread means when clamping the instrument, and FIG 3 is a side view of the surgical instrument according to a preferred embodiment of the invention, the helical thread and the hook means of the second leg being shown in cross-section and the arrows indicating the direction of motion of the second leg when turning the thread means and thus clamping or releasing. Description of a Preferred Embodiment Figs 1-3 show a preferred embodiment of the instrument according to the invention. The instrument has a first and a second leg 1, 2, which are crosswise connected to each other by means of a pivot 9. Each leg 1, 2 has a gripping portion in the form of a loop 3, which is adapted to be gripped by the user's fingers. Furthermore, each leg 1, 2 has a clamping portion 4 adapted to be lo- cated on each side of a blood vessel to clamp the same when the grip loops 3 are moved towards each other, as shown in Fig. 2. Fig. 1 shows the movement of the clamping portions in the opposite direction, i.e. in the re- lease direction. The first leg 1 has a hook means in the form of a circular plate, which in its centre is rotatably mounted on the leg 1 and which on one side has a helical thread 5. Both Figs 1 and 2 show the thread means 5 of the leg 1 and a hook means 6 on the leg 2 when they are engaged with each other, but in different positions. Moreover, arrows indicate the direction of motion of the leg 2 when turning the thread 5. When turning the thread 5 in the clockwise direction, the legs 1, 2 move away from each other, i.e. both the gripping portions 3 and the clamping portions 4 move away from each other, as shown in Fig. 1. Correspondingly, the legs 1, 2, i.e. both the gripping portions 3 and the clamping portions 4, move towards each other when turning the thread 5 in the counter-clockwise direction, as shown in Fig. 2. Fig. 3 shows the engagement of the thread means 5 of the leg 1 with the hook means 6 of the leg 2. The hook means 6 is cam-shaped and pointed in cross-section. That flank 7 of each such portion which is oriented in the direction opposite to the clamping direction is perpendicular to the plane of motion of the legs 1, 2. Correspondingly, the flank 8 of the thread facing the centre of the thread means 5 is perpendicular to the plane of motion of the legs 1, 2. As a result, the legs 1, 2 can- not slide apart by themselves when engaged, but an active force must be applied transversely of the plane of motion of the legs for the hook means to be able to disengage. When clamping a blood vessel by means of the instrument according to the preferred embodiment of the inven- tion, the loops 3 are gripped and the legs 1, 2 are brought together until their respective hook means engage each other. Subsequently, the legs 1, 2 are brought to- gether stepwise, one cut at a time, until a first initial position or a first rough adjustment has been obtained. The thread means 5 can then be turned in the counterclockwise direction so that the legs 1, 2 move in a step- less manner towards each other until the blood flow in the blood vessel has been stopped. Alternatively, the first initial position can be taken, before the turning of the thread means 5 begins, by the legs 1, 2 being displaced in parallel without any contact with each other, and only after this the legs are brought together so that their respective hook means engage each other in this position. When removing the instrument ' from the blood vessel, the legs 1, 2 are displaced in the direction transversely of the plane of motion so that the hook means disengage and then the legs can be moved in the release direction.

Claims: CLAIMS 1. A surgical instrument for providing clamping action around an object, comprising a first leg (1) and a second leg (2) which are articulated to each other by means of a pivot (9) , which have a gripping portion (3) and a clamping portion (4) and which each have at least one hook means (5, 6), the hook means (5) of the first leg (1) being engageable with the hook means (6) of the second leg (2) to establish temporary locking of the clamping portions of the legs at a certain minimum distance from each other and thus static but adjustable clamping action around the object, c h a r a c t e r - i s e d in that the hook means of the first leg (1) comprises a turnable means (5) having at least one thread with a pitch to allow, by turning of the means, stepless fine adjustment of the distance between the clamping portions (4) of the legs (1, 2) . 2. A surgical instrument as claimed in claim 1, wherein the thread is helical. 3. A surgical instrument as claimed in claim 1 or 2 , wherein the thread is arranged on one side of the means (5) which is turnably mounted on the first leg (1) . 4. A surgical instrument as claimed in claim 3, wherein the means (5) is plate-shaped. 5. A surgical instrument as claimed in claim 3 or 4 , wherein the thread is concentric with the turning centre of the means (5) . 6. A surgical instrument as claimed in any one of the preceding claims, wherein the hook means (6) of the second leg (2) comprises one or more cam-shaped portions. 7. A surgical instrument as claimed in claim 6, wherein the cam-shaped portion or portions are pointed in cross-section. 8. A surgical instrument as claimed in claim 6 or 7 , wherein that flank (7) of each cam-shaped portion which is oriented in the direction opposite to the clamping direction of the legs (1, 2) is substantially perpendicular to or makes an angle which is less than 90° with the plane of motion of the legs (1, 2) . 9. A surgical instrument as claimed in any one of the preceding claims, wherein the thread is pointed in cross-section. 10. A surgical instrument as claimed in any one of the preceding claims, wherein the flank (8) facing the turning centre of the means (5) is substantially perpendicular to or makes an angle which is less than 90° with the plane of motion of the legs (1, 2) . 11. A surgical instrument as claimed in any one of the preceding claims, wherein the instrument is stepwise adjustable in a desired initial position from which the instrument is adapted to be finely adjusted in a stepless manner .

Inventors: RISBERG BO, STENBECK ARNE, WINCRANTZ FREDRIK, RISBERG, BO, STENBECK, ARNE, WINCRANTZ, FREDRIK
Applicants: RISBERG BO, STENBECK ARNE, STILLE SURGICAL AB, WINCRANTZ FREDRIK, RISBERG, BO, STENBECK, ARNE, WINCRANTZ, FREDRIK
Application year: 2000
Main classification: A61B17
IPC codes: A61B17