Surgical Shaver

Abstract

The present invention relates to a surgical shaver having a tubular-shaped inner sleeve 4 rotatable about a longitudinal axis 5 of the surgical shaver, which inner sleeve can be coupled to a rotary drive, and a tubular-shaped outer sleeve 3 surrounding the inner sleeve 4 and non-rotatable relative to it. In this case, according to the invention, the free distal ends of the inner sleeve 4 and the outer sleeve 3 are axially open, and the outer sleeve 3 has, in the region of its free end, at least one longitudinally extending and longitudinally projecting cutting web 7, which cutting web has at least one first cutting edge 8 having a longitudinal component and running from a leg region 7a of the cutting web 7, and at least one further cutting edge 9, 12 in the free end region, which further cutting edge has a component directed inwards in the circumferential direction, and the inner sleeve 4 has, in the region of its free end, at least one longitudinally extending and longitudinally projecting first counter web 10, which first counter web extends essentially up to the free end of the at least one cutting web 7. This is what is intended.

Description

[Technical field]

[0001] The present invention relates to a surgical shaver, The surgical shaver has a tubular shaped inner sleeve rotatable about a longitudinal axis of the surgical shaver, the inner sleeve being connectable to a rotary drive; and The surgical shaver has a tubular shaped outer sleeve which surrounds the inner sleeve and is non-rotatable relative to the inner sleeve. [Background technology]

[0002] Arthroscopic and endoscopic procedures are often performed to diagnose and treat joint problems. Thus, for example, ligament reconstruction, bone replenishment, and replacement of worn menisci can be performed by arthroscopic reconstructive procedures, during which the surgeon usually needs to work through a series of relatively small openings. During such procedures, it may be necessary, for example, to remove meniscal or other soft tissue present in the joint cavity (Gelenkraum).

[0003] Surgical shavers are motor-driven instruments which are adapted for various of the abovementioned areas of use, for example for the (partial) resection of meniscal tissue. Such a surgical shaver has a tubular-shaped inner sleeve rotatable about the longitudinal axis of the surgical shaver, the inner sleeve being connectable to a rotary drive device, and the surgical shaver has a tubular-shaped outer sleeve surrounding the inner sleeve and non-rotatable relative to the inner sleeve. The inner sleeve is driven at high rotational speeds (up to more than a thousand revolutions per minute), usually in an oscillating manner, by a rotary drive. A cutting effect is achieved by this (relative) rotational movement between the inner and outer sleeves when the shaver is guided with its cutting edge to the edge of the tissue to be removed at the inner and outer sleeves.

[0004] From DE 10 200 03 133 A1 a surgical shaver is known, which has an outer sleeve and an inner sleeve, which is accommodated rotatably about a longitudinal axis inside the non-rotatable outer sleeve, whereby the inner sleeve can be coupled to a drive motor. The inner sleeve and the outer sleeve have a tapered, distal free end region, whereby an oval window with a cutting edge is cut out in each case in the inner sleeve as well as in the outer sleeve adjacent to this end region. A further development of such a surgical shaver, with a special geometric shape of the window opening, is known from US Pat. No. 5,399,633.

[0005] These known shavers, however, still require improvement, since due to their construction, they are not able to fully reach the tissue to be removed for cutting, due to the construction height of the shaver and the arrangement of the cutting edges, for example, in the narrow joint gap. In some cases, no shaver or other instrument can be used, and therefore relatively long surgical times often result. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] US Patent Application Publication No. 5 741 287 A [Patent Document 2] European Patent Specification No. 2 907 460 B1 Summary of the Invention [Problem to be solved by the invention]

[0007] The object of the present invention is to significantly improve a surgical shaver with regard to its usability and cutting action in order to achieve shorter operating times. [Means for solving the problem]

[0008] This problem is solved according to the invention in a surgical shaver of the type mentioned at the beginning, the free distal ends of the inner sleeve and the outer sleeve being axially open; and the outer sleeve has at least one longitudinally extending and longitudinally projecting cutting web in the region of its free end, the cutting web has at least one first cutting edge having a longitudinal component and extending from a foot region of the cutting web and at least one further cutting edge in the free end region, the further cutting edge having a component directed inwards in the circumferential direction, In this case, the inner sleeve is provided with: - has at least one longitudinally extending and longitudinally projecting first counter web, which first counter web extends essentially up to the free end of the at least one cut web, and, the inner sleeve having at least one longitudinally extending and longitudinally projecting second mating web; the second mating web does not extend to the free end of at least one of the cut webs; is solved by: Effect of the Invention

[0009] By means of such a surgical shaver, significantly better cutting results during tissue removal can be achieved compared to known shavers, and therefore the operation time can be significantly reduced. The shaver is guided with its open distal end to the edge of the tissue to be removed and grasps the tissue edge, i.e. the tissue edge is in this situation located between at least one cutting web and at least one counter web. Subsequently, when the inner sleeve is displaced in a rotational movement, the shaver not only cuts longitudinally with its first cutting edge, as in a conventional shaver, but additionally also cuts circumferentially with a further cutting edge that is aligned inwardly of the shaver, so that tissue can basically be removed in a shorter time. In addition, the shaver can also remove tissue in narrow joint gaps without further procedures, since the shaver can be inserted into the joint gap from the front with its distal free end area.

[0010] In an advantageous embodiment, the inner sleeve having at least one longitudinally extending and longitudinally projecting second mating web; It is provided that the second counter web does not extend up to the free end of the at least one cut web. The outer side of the second counter web is then preferably slightly tapered towards its free end. Particularly preferably, the inner sleeve has two counter webs, a first and a second.

[0011] According to an advantageous embodiment, At least one cutting web is provided with a second cutting edge in an end face side edge region, It is contemplated that the second cutting edge has a circumferentially inwardly directed component. This second cutting edge is then in this embodiment a further cutting edge. The first counter web of the inner sleeve is made long enough that between this second cutting edge and the free distal end of the first counter web in the outer sleeve with the second cutting edge there remains only a ring-shaped gap large enough for cutting of the tissue in the circumferential direction.

[0012] Alternatively or additionally, a third cutting edge is provided adjacent to the first cutting edge in a free end region of at least one of the cutting webs, It is possible for this third cutting edge to have a component directed inwards in the circumferential direction. This third cutting edge is then either a further cutting edge or two further cutting edges are provided, i.e. a second cutting edge and a third cutting edge.

[0013] Furthermore, advantageously, It is provided that at least one of the cutting webs of the outer sleeve has a first cutting edge on each side. This cutting web is then effective in both rotation directions.

[0014] Correspondingly, advantageously, It is provided that at least one of the cutting webs of the outer sleeve has a third cutting edge on each side.

[0015] In yet another embodiment, It is contemplated that the third cutting edge is formed within a recess or bulge in the cutting web. If the cutting web has a third cutting edge on both sides, it is possible that both cutting edges are formed in a depression or in a bulge, or alternatively, one third cutting edge is formed in a depression and the other in a bulge. If the outer sleeve has several cutting webs, it is possible that the third cutting edges of the outer sleeves are formed identically or differently, also in the manner described above.

[0016] Furthermore, advantageously, It is possible that it is provided that the first cutting edge has at least two cutting portions, which have different inclinations relative to the longitudinal axis.

[0017] Yet another embodiment comprises: The first cutting edge is characterized in that it is at least locally curved.

[0018] Likewise, the third cutting edge is also formed at least in areas with a curved shape, in which case it is advantageous if the third cutting edge is formed within a depression or a bulge.

[0019] It is likewise possible for the edge of this or the counter web of the inner sleeve to also be embodied, at least in areas, as a cutting edge.

[0020] The invention will now be explained in more detail by way of example with reference to the figures, which are respectively shown in three-dimensional representation. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is an overall view of a surgical shaver. [Diagram 2] FIG. 2 is a partial view of the shaver according to the first embodiment. [Diagram 3]3 is a view of the shaver according to FIG. 2 in a second position. [Figure 4] FIG. 3 is a view of the shaver according to FIG. 2 in a third position. [Diagram 5] FIG. 3 is a partial view of the outer sleeve of the shaver according to FIG. 2; [Figure 6] FIG. 6 is a view of the outer sleeve according to FIG. 5 from another perspective. [Figure 7] FIG. 3 is a partial view of the inner sleeve of the shaver according to FIG. 2; [Figure 8] 8 is a view of the inner sleeve according to FIG. 7 from a second perspective. [Figure 9] FIG. 8 is a view of the inner sleeve according to FIG. 7 from a third perspective. [Figure 10] FIG. 11 is a partial view of an outer sleeve in the second embodiment. [Figure 11] FIG. 11 is a view of the outer sleeve according to FIG. 10 from a second perspective. [Figure 12] FIG. 11 is a view of the outer sleeve according to FIG. 10 from a third perspective. [Figure 13] 11 is a partial view of a shaver having an outer sleeve according to FIG. 10 and an inner sleeve according to FIG. 7. [Figure 14] FIG. 14 is a diagram of the shaver according to FIG. 13 in a second position. [Figure 15] FIG. 14 is a view of the shaver according to FIG. 13 in a third position. [Figure 16] FIG. 10 is a partial view of an outer sleeve in the third embodiment. [Figure 17] FIG. 10 is a partial view of an outer sleeve in the fourth embodiment. [Figure 18] FIG. 10 is a partial view of an outer sleeve in the fifth embodiment. [Figure 19] FIG. 13 is a partial view of the outer sleeve in the sixth embodiment. [Figure 20] FIG. 13 is a partial view of the outer sleeve in the seventh embodiment. [Figure 21] FIG. 21 is a view of the outer sleeve according to FIG. 20 from a second perspective. [Figure 22]FIG. 23 is a partial view of the outer sleeve in the eighth embodiment. [Diagram 23] FIG. 23 is a view of the outer sleeve according to FIG. 22 from a second perspective. [Figure 24] FIG. 13 is a partial view of the outer sleeve in the ninth embodiment. [Diagram 25] FIG. 23 is a partial view of the outer sleeve in the tenth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] A surgical shaver according to the present invention is indicated generally by the reference numeral 1 in FIG. At its rear end, the shaver 1 has a connecting piece 2 for connection to a rotary drive (not shown), designated by the reference number 2. In this connecting piece 2, a tubular-shaped outer sleeve 3 is arranged non-rotatably. A tubular-shaped inner sleeve 4 is accommodated inside this outer sleeve 3, which is rotatable relative to the outer sleeve 3 about the longitudinal axis 5 of the shaver 1. For this purpose, the inner sleeve 4 is connected in the usual way via a connecting piece 2 to the rotation shaft of a rotary drive. The rotary drive is capable of putting the inner sleeve 4 into a rotary motion, preferably oscillatingly, at high rotational speeds (several thousand revolutions per minute). The annular gap between the inner sleeve 4 and the outer sleeve 3 is dimensioned in such a way that the inner sleeve 4 is, on the one hand, guided approximately centrally with respect to the longitudinal axis 5 and, on the other hand, accommodated freely rotatably inside the outer sleeve 3.

[0023] The configuration of the shaver 1 in its free distal end region, generally designated in FIG. 1 by reference number 6, or the configuration of the outer sleeve 3 and the inner sleeve 4 in its free distal end region 6, is fundamental to the invention. This configuration is illustrated in various embodiments in FIGS. 2 to 25, where the outer sleeve 3 as well as the inner sleeve 4, respectively, are only shown in the free end region 6 of the shaver 1. The free distal end regions 6 of the inner sleeve 4 and of the outer sleeve 3 are in all embodiments open in the longitudinal direction, i.e. in the direction of the longitudinal axis 5, and therefore The shaver 1 can grasp the edge of tissue (not shown) to be separated (e.g. meniscus tissue) with its free end region 6 when the longitudinal axis 5 of the shaver 1 approximately coincides with the surface of the tissue.

[0024] A first embodiment of the outer sleeve 3 and the inner sleeve 4 is shown in a strongly enlarged view in Figures 2 to 9. The outer sleeve 3 has at least one longitudinally extending and longitudinally projecting cutting web 7 in the region of its free end adjacent to its tubular-shaped region 3a, whereby in all illustrated embodiments two cutting webs 7 are provided. Each cutting web 7 has a first cutting edge 8 with a longitudinal component which starts from the foot region 7a of the cutting web 7 and which, in the first embodiment, is configured in a curved shape. Each cutting web 7 has, in the free end region 6, at least one further cutting edge which further has a component directed inwards in the circumferential direction. In the first embodiment according to Figures 2 to 6, this further cutting edge is formed by a second cutting edge 9 in the end edge region 7b of the cutting web 7. Both cutting webs 7 are formed identically in the first embodiment.

[0025] Adjacent to the tubular region 4a of the inner sleeve, in the region of the free end of the inner sleeve, the inner sleeve 4 has at least one first mating web 10 extending longitudinally and projecting longitudinally, which first mating web extends essentially up to the free end of the at least one cutting web 7. As can best be seen from Figures 2 to 4, in the first embodiment the first mating web 10 is only slightly shorter than the respective cutting web 7, so that between the free end of this first mating web 10 and the second cutting edge 9 a ring-shaped gap remains for the tissue to be separated. The longitudinal edges 10a of the first counter web 10 are then preferably designed in such a way that they likewise form cutting edges.

[0026] In the first embodiment, the inner sleeve 4 has two identically constructed counter webs 10. Furthermore, the inner sleeve 4 has at least one longitudinally extending and longitudinally projecting second counter web 11 which does not extend all the way to the free end of the at least one cutting web 7, but rather is preferably configured to be significantly shorter. The second counter web 11 is then preferably configured such that its outer side 11a tapers slightly inwards, so that the distance between the second counter web 11 and the cutting web 7, viewed in the longitudinal direction, increases towards the free end of the second counter web 11. The longitudinal edge 11b of the second counter web 11 is then preferably configured such that it likewise forms a cutting edge.

[0027] In figures 2 to 4 three different rotational positions between the outer sleeve 3 and the inner sleeve 4 are illustrated. In the position according to FIG. 2, the first mating web 10 is adjacent to the cutting web 7 (obviously with a certain distance therebetween) so that the free distal end of the first mating web 10 is located in the area of ​​the second cutting edge 9 of the cutting web 7, whereby the tissue (not shown) is cut in the circumferential direction by the second cutting edge 9. In addition, the longitudinal edge 10a of the first counter web 10 is in approximately point-like adjoining state with the first cutting edge 8, so that the tissue, not shown, is essentially cut in the longitudinal direction by the first cutting edge 8. 3 and 4 show further rotational positions of the cutting web 7 and the first and second counter webs 10 and 11 with correspondingly changed spatial correspondence.

[0028] It can be seen that due to the configuration of the shaver 1, i.e. the free end region 6 of the shaver, the tissue to be separated is not only cut essentially in the longitudinal direction, as in known shavers, but also additionally in the circumferential direction.

[0029] 10 to 12, a second embodiment of the outer sleeve 3 is shown. In contrast to the first embodiment, each cutting web 7 has, on one side, adjacent to the first cutting edge 8, a further cutting edge 9, i.e. a third cutting edge 12, which has a component directed inwards in the circumferential direction. This third cutting edge 12 is formed in a recess 13 of the cutting web 7 and is formed with a curved shape. The third cutting edge 12 merges towards the free distal end into the second cutting edge 9. In a variant of this embodiment, the second cutting edge 9 can be omitted, in which case the third cutting edge 12 is the only further cutting edge.

[0030] In this embodiment, the recesses 13 of both cutting webs 7 are oriented in opposite directions relative to one another when viewed in the circumferential direction, so that only one of the two third cutting edge portions 12 is effective depending on the respective direction of rotation. In a further alternative configuration, it is also possible that on both sides of each cutting web 7 there is provided a recess 13 with a third cutting edge 12. As shown, however, it is also possible that the side surfaces of the cutting web 7 are formed without a recess 13, as in the first embodiment.

[0031] In figures 13 to 15 the outer sleeve 3 according to the second embodiment is illustrated together with the inner sleeve 4 remaining unchanged in three different rotational positions.

[0032] In FIG. 16 a third embodiment of the outer sleeve 3 is shown. In this embodiment, the outer sleeve 3 has a third cutting edge 12 on one cutting web 7, which is curved along a bulge 14. Basically, it is also possible for both cutting webs 7 to have at least one bulge 14 each with a third cutting edge 12 in this third embodiment. It is likewise possible for one cutting web 7 to have on one side a depression 13 with a third cutting edge 12 and on the other side a bulge 14 with a third cutting edge 12. If two cutting webs 7 are provided, it is possible for these to be provided with at least one depression 13 and / or one bulge 14 in different orientation directions.

[0033] In FIG. 17 a fourth embodiment of the outer sleeve 3 is shown, which differs from the outer sleeve according to FIG. 16 only in that the bulge 14 and the third cutting edge 12 formed in this bulge 14 are not formed in a curved shape, but rather also in a rectangular shape.

[0034] Figure 18 shows a fifth embodiment of the outer sleeve 3. In this embodiment, in the cutting web 7, a recess 13 is provided which has a rectangular shape. The third cutting edge 12 then merges into the second cutting edge 9. In this embodiment, in contrast to the second embodiment, only one cutting web 7 is provided with a recess 13.

[0035] Figure 19 shows a sixth embodiment of the outer sleeve 3. This embodiment differs from the outer sleeve according to Figure 18 only by the curved shape of the recess 13 and therefore of the course of the third cutting edge 12.

[0036] Figures 20 and 21 show the outer sleeve 3 in a seventh embodiment. In one cutting web 7, the first cutting edge 8 has two cutting portions 8a and 8b, which have different inclinations relative to the longitudinal axis 5. The first cutting portion 8a is curved, whereas the second cutting portion 8b is essentially linear. It is further provided that in this cutting web 7 the second cutting edge 9 is joined to a ring-shaped web 15 .

[0037] 22 and 23 show an eighth embodiment of the outer sleeve 3. This eighth embodiment of the outer sleeve 3 differs from the seventh embodiment only in that the web 15 is omitted.

[0038] In FIG. 24 a ninth embodiment of the outer sleeve 3 is shown. In this embodiment, two cutting webs 7 are provided, one cutting web 7 having a curved recess 13 with a third cutting edge 12 and the other cutting web 7 having a curved bulge 14 with a third cutting edge 12. In addition, a first cutting edge 8 and a second cutting edge 9 are provided in both cutting webs 7.

[0039] Finally, in Fig. 25 a tenth embodiment of the outer sleeve 3 is shown, which also differs from the ninth embodiment in that the depression 13 with the third cutting edge 12 on the one cutting web 7 and the bulge 14 with the third cutting edge 12 on the other cutting web 7 are not formed in a curved shape, but rather in a rectangular shape.

[0040] Needless to say, the invention is not limited to the illustrated embodiment: further embodiments are possible without departing from the basic idea. Different geometric configurations of the outer sleeve 3 within the scope of the above-mentioned embodiments can therefore be combined with one another in any suitable manner. Thus, it is possible for one cutting web 7 to have one depression 13 on one side and one bulge 14 on the other side. Basically, it is also possible that only one cutting web 7 is provided or, alternatively, that more than two cutting webs are provided. It is also possible that the inner sleeve 4 has only one first counter web 10 with or without a second counter web 11. In addition, the present application relates to the invention described in the claims, but may also include the following as other aspects. 1. A surgical shaver comprising: The surgical shaver has a tubular inner sleeve (4) rotatable about a longitudinal axis (5) of the surgical shaver, the inner sleeve being connectable to a rotary drive; and The surgical shaver has a tubular outer sleeve (3) surrounding the inner sleeve (4) and non-rotatable relative to the inner sleeve, the free distal ends of the inner sleeve (4) and the outer sleeve (3) being axially open, and the outer sleeve (3) has, in the region of its free end, at least one longitudinally extending and longitudinally projecting cutting web (7), the cutting web has at least one first cutting edge (8) having a longitudinal component and extending from a foot region (7a) of the cutting web (7) and at least one further cutting edge (9, 12) in the free end region, the further cutting edge having a component directed inwards in the circumferential direction, in which the inner sleeve (4) has, in the region of its free end, at least one longitudinally extending and longitudinally projecting first counter web (10), which extends essentially up to the free end of the at least one cutting web (7); A surgical shaver characterized by: 2. The inner sleeve (4) has at least one longitudinally extending and longitudinally projecting second mating web (11); 2. The shaver according to claim 1, characterized in that the second counter web does not extend up to the free end of at least one cutting web (7). 3. At least one of the cutting webs (7) is provided with a second cutting edge (9) in the end edge region (7b), 3. A shaver as claimed in claim 1 or 2, characterized in that the second cutting edge portion has a component which is directed inwards in the circumferential direction. 4. A third cutting edge (12) is provided adjacent to the first cutting edge (8) in the free end region of at least one of the cutting webs (7), 4. A shaver as claimed in any one of claims 1 to 3, characterised in that the third cutting edge portion has a component which is directed inwards in the circumferential direction. 5. A shaver according to any one of claims 1 to 4, characterized in that at least one of the cutting webs (7) of the outer sleeve (3) has one first cutting edge portion (8) on each side. 6. A shaver as claimed in claim 4 or 5, characterized in that at least one of the cutting webs (7) of the outer sleeve (3) has one third cutting edge portion (12) on each side. 7. A shaver as described in any one of claims 4 to 6, characterized in that the third cutting edge portion (12) is formed within a depression (13) or bulge (14) of the cutting web (7). 8. A shaver as described in any one of claims 1 to 7, characterized in that the first cutting edge (8) has at least two cutting portions (8a, 8b), which have different inclinations relative to the longitudinal axis (5). 9. The shaver according to any one of 1 to 7 above, wherein the first cutting edge portion (8) is formed in a curved shape at least in a region thereof. 10. The shaver according to any one of 1 to 9 above, wherein the third cutting edge portion (12) is formed in a curved shape at least in a region thereof. [Explanation of symbols]

[0041] 1. Surgical shaver 2 Connecting pieces 3 Outer Sleeve 3a Tube Shape Area 4 Inner Sleeve 4a Tube Shape Area 5 Longitudinal axis 6 Free edge area 7 Cutting Web 7a Leg area 7b Edge area 8 First cutting edge 8a First cut portion 8b Second cut part 9 Second cutting edge 10 First Counterparty Web 10a Longitudinal edge portion 11 Second Partner Web 11a External surface 11b Longitudinal edge portion 12 Third cutting edge 13 Recess 14 Bulge 15. Web

Claims

1. 1. A surgical shaver, comprising: The surgical shaver has a tubular inner sleeve (4) rotatable about a longitudinal axis (5) of the surgical shaver, the inner sleeve being connectable to a rotary drive; and The surgical shaver has a tubular outer sleeve (3) surrounding the inner sleeve (4) and non-rotatable relative to the inner sleeve, the free distal ends of the inner sleeve (4) and the outer sleeve (3) being axially open, and the outer sleeve (3) has, in the region of its free end, at least one longitudinally extending and longitudinally projecting cutting web (7), the cutting web has at least one first cutting edge (8) having a longitudinal component and extending from a foot region (7a) of the cutting web (7) and at least one further cutting edge (9, 12) in the free end region, the further cutting edge having a component directed inwards in the circumferential direction, In this case, the inner sleeve (4) has, in the region of its free end, at least one longitudinally extending and longitudinally projecting first counter web (10), which extends essentially up to the free end of the at least one cutting web (7), and the inner sleeve (4) having at least one longitudinally extending and longitudinally projecting second mating web (11); the second counter web does not extend up to the free end of at least one of the cut webs (7); A surgical shaver characterized by:

2. At least one of the cutting webs (7) is provided with a second cutting edge (9) in the end edge region (7b), 2. A shaver according to claim 1, wherein the second cutting edge has a circumferentially inwardly directed component.

3. a third cutting edge (12) is provided adjacent to the first cutting edge (8) in a free end region of at least one of the cutting webs (7), 3. A shaver according to claim 1 or 2, characterized in that the third cutting edge has a component which is directed inwards in the circumferential direction.

4. 4. A shaver according to claim 1, wherein at least one of the cutting webs (7) of the outer sleeve (3) has a first cutting edge (8) on each side.

5. 5. Shaver according to claim 3 or 4, characterized in that at least one of the cutting webs (7) of the outer sleeve (3) has a third cutting edge (12) on each side.

6. 6. A shaver according to claim 3, wherein the third cutting edge (12) is formed in a depression (13) or a bulge (14) of the cutting web (7).

7. 7. A shaver according to any one of the preceding claims, characterized in that the first cutting edge (8) has at least two cutting portions (8a, 8b) having different inclinations relative to the longitudinal axis (5).

8. 7. A shaver according to claim 1, wherein the first cutting edge (8) is at least in areas formed with a curved shape.

9. 4. A shaver according to claim 3, characterized in that the third cutting edge (12) is at least in areas formed with a curved shape.

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