Trocar sleeve with an asymmetrical helix

Abstract

A trocar sleeve has a hollow shaft having a distal end and a proximal end, the shaft having a rectilinear shaft axis, an external thread rising from an outer surface of the shaft, wherein a first external thread having a shape of a helix has a height, measured from the outer surface up to a vertex of the helix, the height of the helix, seen along the rectilinear shaft axis from distal to proximal increases, and wherein a pitch of the helix, seen along the rectilinear shaft axis from distal to proximal decreases.

Claims

1. A trocar sleeve, comprising: a hollow shaft having a distal end and a proximal end, said shaft having a rectilinear shaft axis; and an external thread rising from an outer surface of said shaft, said external thread comprising a first external thread having a shape of a helix has a height, measured from said outer surface up to a vertex of said helix; wherein said height of said helix is non-constant and increases gradually in a direction extending along said rectilinear shaft axis from said distal end toward said proximal end; wherein a pitch of said helix is non-constant and decreases gradually in a direction extending along said rectilinear shaft axis from said distal end toward said proximal end; wherein said helix has a distal flank and a proximal flank; and wherein an angle of said proximal flank with respect to said rectilinear shaft axis is non-constant and decreases gradually in a direction extending along said rectilinear shaft axis from said distal end toward said proximal end, said angle defined between said proximal flank and said rectilinear shaft axis in a plane in which said rectilinear shaft axis extends.

2. The trocar sleeve of claim 1, wherein said angle of said proximal flank decreases up to approximately 90 degrees.

3. The trocar sleeve of claim 1, wherein said height of said helix increases constantly.

4. The trocar sleeve of claim 1, wherein an angle of gradient of said pitch of said helix, with respect to a plane extending perpendicular to said rectilinear shaft axis and in a direction extending along said rectilinear shaft axis from said proximal end toward said distal end, changes from an acute angle of more than 45 degrees to an angle of less than 20 degrees.

5. The trocar sleeve of claim 1, wherein said pitch of said helix amounts approximately half of a thickness of a tissue through which said trocar sleeve has to be turned in.

6. The trocar sleeve of claim 1, wherein said helix extends about two windings of said thread.

7. The trocar sleeve of claim 1, wherein distally to said helix a distal portion of said outside of said shaft is present without a thread.

8. The trocar sleeve of claim 1, wherein said helix extends over one section of said shaft only.

9. The trocar sleeve of claim 1, wherein said hollow shaft is cylindrical.

10. The trocar sleeve of claim 1, wherein said hollow shaft and said first external thread are integrally shaped.

11. The trocar sleeve of claim 1, wherein said height of said helix is non-constant and increases gradually in said direction extending along said rectilinear shaft axis, such that such that said height has a first height magnitude at a distal position along said helix, and said height has a second height magnitude at a proximal position along said helix, said first height magnitude being less than said second height magnitude; wherein a pitch of said helix is non-constant and decreases gradually in said direction extending, such that said pitch has a first pitch magnitude at a distal position along said helix, and said pitch has a second pitch magnitude at a proximal position along said helix, said first pitch magnitude being greater than said second pitch magnitude; and wherein said angle of said proximal flank with respect to said rectilinear shaft axis is non-constant and decreases gradually in said direction extending along said rectilinear shaft axis, such that said angle has a first angle magnitude at a distal position along said helix, and said angle has a second angle magnitude at a proximal position along said helix, said first angle magnitude being greater than said second angle magnitude.

12. The trocar sleeve of claim 1, wherein said height of said helix increases from zero to a maximum height.

13. The trocar sleeve of claim 12, wherein said maximum height amounts up to an external diameter of said shaft.

14. The trocar sleeve of claim 1, wherein said height of said helix increases from zero to a maximum height, and wherein said height, following to said maximum height, decreases to zero.

15. The trocar sleeve of claim 14, wherein said height following to said maximum height, decreases to zero within at most one 360 degree winding of said helix.

16. The trocar sleeve of claim 1, wherein said shaft is made from a flexible material.

17. The trocar sleeve of claim 16, wherein said flexible material is a plastic material.

18. The trocar sleeve of claim 1, wherein a retainer is arranged on said outside of said shaft proximal to said helix, wherein said retainer is movable along said rectilinear shaft axis and arranged to be placed on an outer surface of a tissue through which the trocar sleeve has to be turned through.

19. The trocar sleeve of claim 18, wherein said retainer is designed as a slit element that is arranged to be clipped laterally onto said shaft.

20. The trocar sleeve of claim 18, wherein said retainer is designed as a disc-like element which is movable along said rectilinear shaft axis and which retainer is held stationary on said shaft in at least one position.

21. The trocar sleeve of claim 18, wherein said retainer is made from a flexible plastic material, and wherein said retainer is movable axially to and fro over a second external thread on said outer surface of said shaft.

22. The trocar sleeve of claim 18, wherein said retainer has an internal thread, and wherein said outer surface of said shaft is provided with a second external thread on a side proximal to said helix, said retainer is arranged to be axially moved to and fro over said second external thread.

23. The trocar sleeve of claim 22, wherein a thread-free shaft portion is present between said helix and said second external thread.

24. A trocar sleeve, comprising: a shaft having a rectilinear shaft axis extending between a distal end and a proximal end of the shaft, the shaft being hollow; and an external thread rising from an outer surface of the shaft, the external thread being helically-shaped and having a distal flank, a proximal flank, and a vertex where the distal flank and the proximal flank meet, and the external thread having a height defined between the outer surface of the shaft and the vertex of the external thread; wherein the height of the external thread is non-constant and increases in a direction extending along the rectilinear shaft axis from the distal end toward the proximal end, such that the height has a first height magnitude at a distal position along the external thread, and the height has a second height magnitude at a proximal position along the external thread, the first height magnitude being less than the second height magnitude; wherein a pitch of the external thread is non-constant and decreases in a direction extending along the rectilinear shaft axis from the distal end toward the proximal end, such that the pitch has a first pitch magnitude at a distal position along the external thread, and the pitch has a second pitch magnitude at a proximal position along the external thread, the first pitch magnitude being greater than the second pitch magnitude; and wherein an angle is defined between the proximal flank and the rectilinear shaft axis in a plane in which the rectilinear shaft axis extends, and the angle is non-constant and decreases in a direction extending along the rectilinear shaft axis from the distal end toward the proximal end, such that the angle has a first angle magnitude at a distal position along the external thread, and the angle has a second angle magnitude at a proximal position along the external thread, the first angle magnitude being greater than the second angle magnitude.

25. The trocar sleeve of claim 24, wherein the height of the external thread increases gradually in the direction extending along the rectilinear shaft axis from the distal end toward the proximal end; wherein the pitch of the external thread decreases gradually in the direction extending along the rectilinear shaft axis from the distal end toward the proximal end; and wherein the angle is non-constant and decreases gradually in the direction extending along the rectilinear shaft axis from the distal end toward the proximal end.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described and explained in more detail below with reference to the attached drawings, in which:

(2) FIG. 1 shows a perspective view of a trocar sleeve according to the invention without a proximal seal,

(3) FIG. 2 shows a side view of the trocar sleeve with a proximal seal,

(4) FIG. 2a shows a side view of the trocar sleeve with demonstrating an angle of gradient of the helix,

(5) FIG. 3 shows a longitudinal section along the line III-III in FIG. 2 in the area of the helix,

(6) FIG. 4 shows a cross section along the line IV-IV in FIG. 2,

(7) FIG. 5 shows a cross section along the line V-V in FIG. 2,

(8) FIG. 6 shows a cross section along the line VI-VI in FIG. 2,

(9) FIG. 7 shows a cross section along the line VII-VII in FIG. 2,

(10) FIG. 8 shows a cross section along the line VIII-VIII in FIG. 2,

(11) FIG. 9 shows a partial side view of the trocar sleeve with a trocar mandrel pushed in shortly before placement on an abdominal wall,

(12) FIG. 10 shows a view corresponding to FIG. 9, in a situation in which a distal end portion of the shaft has already been pushed through the abdominal wall and the trocar has been withdrawn,

(13) FIG. 11 shows a situation comparable to FIG. 10 as the helix begins to be screwed into the abdominal wall,

(14) FIG. 12 shows a situation in which the helix has been screwed completely through the abdominal wall, and

(15) FIG. 13 shows a situation in which a retainer is placed onto the outer face of the abdominal wall.

DETAILED DESCRIPTION OF THE INVENTION

(16) A trocar sleeve shown in the figures is designated in its entirety by reference number 10.

(17) As can be seen in particular from FIGS. 1 and 2, the trocar sleeve 10 has a rectilinearly extending hollow shaft 12, which has a shaft axis 13. The shaft 12 is cylindrical and has a cylindrical outer face 22.

(18) The shaft 12 has an open distal end 14 and is provided, at its proximal end, with a housing 18 that can be closed in a gas-tight manner by a seal 20 (FIG. 2). As can be seen from FIGS. 1 and 2, the outer face 22 is smooth in a distal end portion 24 of the shaft 12, i.e. has no thread there.

(19) This distal end portion 24 is adjoined in the proximal direction by a longitudinal portion 25 on which a first external thread 26 is present in the form of a helix 28, wherein the helix 28 rises from the cylindrical outer face 22 of the shaft 12.

(20) The exact design of the helix 28 will first be described and explained in detail in particular in connection with FIG. 2 and with the sectional views in FIGS. 3 to 8.

(21) In the illustrative embodiment shown, the helix 28 is constructed from a helical winding which has approximately two complete thread turns.

(22) As can be seen from FIG. 2a, the helix 28 and the respective vertex line of the first outer thread has an angle of gradient with respect to a plane perpendicular to the shaft axis 13, which changes, seen from distal to proximal, from an acute angle of more than 45 degrees to an angle of less than 20 degrees. The vertex line is the line where all vertices of the helix lie.

(23) It will be seen from the sectional views in FIGS. 3 and 4 that, viewed from the distal end 14 in the direction of the proximal end 16, the helix 28 rises from a height zero through a height H1 and a height H2 to a maximum height H3. The increase is constant.

(24) The helix begins at a height zero, then immediately rises to a height of approximately 2.7 mm, has a height of 5 mm in the area of the cross section in FIG. 5, and it has a height of 6.5 mm at the level of the cross sections in FIGS. 6 and 7. Following the maximum height H3 of approximately 6.5 mm, the height drops very rapidly again (ca. 90) to a very low height of approximately 2.7 mm, as is shown in FIG. 8.

(25) The respective heights are indicated in FIGS. 5 to 8 by the vertices S5, S6, S7 and S8.

(26) Turning now to FIG. 2, it will be seen that the pitch of the helix decreases continuously from distal to proximal. The pitch is defined by the height difference of two opposite vertices after a 360 rotation.

(27) The pitch at the start of the helix 28, i.e. according to the cross section in FIG. 4, is 20 mm per revolution, the pitch in the area of the cross section in FIG. 5 is in the range of 10 mm per revolution, the pitch in the area of the cross section in FIG. 6 is in the range of 7 mm per revolution, and the pitch in the area of the cross section in FIG. 7 is only 4 mm per revolution. Following the maximum, the pitch is 8 mm per revolution.

(28) The term per revolution is to be understood as meaning that, if one takes this point and if one were to make a complete revolution, this pitch would result.

(29) In actual fact, however, the pitch of the helix 28 changes continuously from distal to proximal.

(30) It will be seen in particular from the sectional view in FIG. 3 that the angle of the distal flank 48 of the helix 28 remains almost unchanged.

(31) However, the angle of the flank 50 directed towards the proximal end decreases continuously. The flank angle of the flank 50 is the angle between the flank 50 and, seen from distal to proximal, the shaft axis 13. Thus, at the start of the helix, the flank angle .sub.1 with respect to the shaft axis 13, seen from distal to proximal, is approximately 140. This flank angle decreases such that, for example, the flank angle .sub.2 is approximately 130. In the area of the last winding, i.e. in the area of the maximum height H.sub.3 , the flank angle .sub.3 is not quite 100.

(32) Overall, the height H of the helix 28 in the shaft portion 25 thus increases from zero to the maximum height H.sub.3 and then drops rapidly. The whole thread turn of the helix 28 includes approximately two complete 360 revolutions.

(33) At the same time, the pitch decreases, seen from distal to proximal, and the angle of the flank of the helix with respect to the shaft axis 13, directed towards the proximal end, becomes ever smaller.

(34) Returning to FIGS. 1 and 2, it will first be noted that the shaft portion 25 with the helix 28 is adjoined by a thread-free portion 37. Following this thread-free portion 37, a second external thread 30 rises from the outer face 22 of the shaft, but this second external thread is configured as a regular external thread with a constant height, constant pitch and constant flank shape.

(35) A retainer 34 in the form of a triangular disc 36 is received on this second external thread 30. The retainer 34 is made from a flexible silicone material. The triangular disc 36 can be moved axially in the proximal or distal direction. The triangular shape makes it easier to grip and turn or move the retainer. In the area of its central opening 32, the flexible silicone material bears, as as result of deformation, on the contour of the second external thread 30.

(36) An example of a use of the trocar sleeve 10 according to the invention in laparoscopy will be described with reference to the sequence of FIGS. 9 to 13.

(37) As can be seen from FIG. 9, a trocar mandrel 42 is pushed into the inner space of the shaft 12 and its tip 44 extends past the distal end of the trocar sleeve 10. This tip 44 is placed on an incision 46 on the upper or outer face 41 of an abdominal wall 40. When this assembly is pushed forward axially, the trocar sleeve 10 is initially pushed via the smooth distal end portion 24 through the abdominal wall 40, until the helix 28 reaches the upper face 41, as is shown in FIG. 10. The trocar mandrel 42 can now be withdrawn.

(38) As can be seen from the transition from FIG. 10 to FIG. 11, the helix 28 is now screwed gradually through the abdominal wall 40. It is therefore the area of the helix 28 provided with the low height but with the high pitch that is first to enter the abdominal wall. The trocar sleeve 10 can thus be screwed in by a certain distance through a 360 revolution, as can be seen from the transition from FIG. 10 to FIG. 11.

(39) By further rotation of the trocar sleeve 10 about the shaft axis 13, the helix 28 is screwed in further and all the way through the abdominal wall 40. This is shown in FIG. 12. It is clear that at least one further 360 revolution was necessary for this. The first outer thread 26 has only two complete windings. The overall pitch of the two windings approximately corresponds to the height of the tissue, i.e. the abdominal wall 40 through which the trocar sleeve 10 has to be turned.

(40) From FIG. 11 it can be seen that in the direction of the axis relatively large surface areas between the windings 29 and 31 are present, onto which free space, the tissue of the abdominal wall can rest. Less tissue has to be dilated resulting in less stress and turning through of the helix 28 needs less force. Additionally, less torsional stresses act on the shaft during turning. This opens to produce the shaft from a flexible plastic material. This also opens the possibility to form the shaft together with the helix with a blow-mold procedure.

(41) The proximal flank 50 with the small inclination angle .sub.3 (see FIG. 3) now lies opposite the underside 43 of the abdominal wall 40. At the same time, the height H of the helix 28 is at its most pronounced in this area. It is thus clear from FIG. 12 that the helix 28 offers considerable resistance to an axial movement of the trocar sleeve 10 in the proximal direction.

(42) This prevents a situation in which, during the usual manipulations, the trocar sleeve 10 is inadvertently withdrawn from the abdominal wall 40.

(43) The retainer 34 is provided as an additional safety feature, it being possible for the retainer 34 to be rotated about the second external thread 30 until its underside comes to lie on the upper face 41 of the abdominal wall 40, as is shown in FIG. 13.

(44) In this position, the trocar sleeve 10 is secured against axial movement both in the proximal direction and also in the distal direction and is also held relatively stable against tilting. It will be seen from FIG. 13 that the tissue in the area of the opening in the abdominal wall 40 has positioned itself around the thread-free, smooth portion 37 between the end of the helix 28 and the start of the second external thread 30. That is to say, the tissue is not adversely affected by the two external threads 26 and 30, not even during protracted interventions.

(45) After completion of the surgical procedure, the trocar sleeve 10 is unscrewed again from the abdominal wall 40, this being made easier by the fact that the helix 28 is continued proximally of the maximum elevation to the height zero but with a small pitch.