Abstract
A sonotrode suitable for use with an ultrasonic surgical instrument for cutting or punching bones, as well as a method for manufacturing the sonotrode.
Claims
1. A sonotrode for an ultrasonic surgical instrument being suitable for punching out tissue areas from bone, wherein the sonotrode has a head and a distal end piece, the distal end piece being equipped as a stamp for penetration of bones using mechanical vibration.
2. The sonotrode according to claim 1, wherein the distal end piece comprises a blade whose distal cutting edge corresponds to the contour of a tissue area that is to be punched out.
3. The sonotrode according to claim 1, wherein the distal end piece or the blade is designed as a hollow body being open at its distal end.
4. The sonotrode according to claim 3, wherein the hollow body is not rotationally symmetric.
5. The sonotrode according to claim 3, wherein the hollow body is a hollow elliptic cylinder.
6. The sonotrode according to claim 1, wherein the sonotrode has a lateral rib running along a longitudinal axis of the sonotrode.
7. The sonotrode according to claim 6, wherein the sonotrode has one lateral rib inside of the distal end piece or the blade and a second lateral rib outside of the distal end piece or the blade.
8. The sonotrode according to claim 6, wherein the sonotrode has two lateral ribs being located outside of the distal end piece or blade or two lateral ribs being located inside of the distal end piece or blade.
9. The sonotrode according to claim 6, wherein the rib or ribs run only along the distal end piece of the sonotrode.
10. The sonotrode according to claim 6, wherein the at least one rib has a flattened distal end.
11. A sonotrode for an ultrasonic surgical instrument, wherein the sonotrode has a head and a distal end piece, the distal end piece being equipped as a punch for penetration of bones or a blade for cutting and the distal end piece has a maximal diameter being at least one and a half times the size of the diameter of the head.
12. The sonotrode according to claim 11, wherein the distal end piece has a maximal diameter being at least three times the size of the diameter of the head.
13. The sonotrode according to claim 11, wherein the distal end piece comprises a blade whose distal cutting edge corresponds to the contour of a tissue area that is to be punched out.
14. The sonotrode according to claim 11, comprising an intermediate element between the distal end piece and the head.
15. The sonotrode according to claim 14, wherein the intermediate element comprises through holes.
16. The sonotrode according to claim 11, wherein the distal end piece has a sharpened distal edge as cutting edge.
17. The sonotrode according to claim 1, further comprising a sleeve with a window which allows that only a part of the distal end of the sonotrode protrudes out of the sleeve.
18. The sonotrode according to claim 11, wherein the surface of the sonotrode or the surface of the blade has a roughness average Ra between 5-40 μm.
19. The sonotrode according to claim 11, wherein the sonotrode or at least the blade of the sonotrode is manufactured using an additive manufacturing method such as direct metal laser sintering.
20. The sonotrode according to claim 11, comprising a distal rim being a distal outward protrusion extending along the cutting edge, whereby an outer cross section of the sonotrode proximally of the rim is smaller than an outer cross section of the rim.
21. The sonotrode according to claim 11, further comprising a suction port for applying a vacuum in an interior of the sonotrode.
22. The sonotrode according to claim 11, comprising at least one interior blade arranged in an interior of a hollow body of the sonotrode, the hollow body being open at its distal end, the blade configured for breaking up punched-out bone fragments.
23. The sonotrode according to claim 22, comprising a plurality of interior blades, at least two of the interior blades being arranged in a staggered manner.
24. The sonotrode according to claim 11, wherein a distal end forming a cutting edge forms a closed contour.
25. The sonotrode according to claim 11, wherein the distal end piece defines an axis around which the distal end piece extends, and wherein a distal end forming a cutting edge follows a curve in 3D space, which curve is different from a curve extending in a plane perpendicular to the axis.
26. The sonotrode according to claim 25, wherein the curve extends in a plane that is at an angle to the axis, which angle is different from 90° and different from 0°
27. A surgical punching device, comprising a sonotrode according to claim 1, and further comprising a tube encompassing the sonotrode.
28. The device according to claim 27, wherein the tube is equipped to supply a liquid to the distal end of the sonotrode.
29. An ultrasonic surgical instrument for cutting bones, comprising a housing containing an ultrasonic transducer and a sonotrode as defined in claim 1 mechanically coupled to said transducer.
30. The instrument according to claim 29, further comprising a suction device equipped to apply a vacuum in an interior or the sonotrode or in a vicinity of the sonotrode.
31. The instrument according to claim 29, further comprising a liquid supply for supplying a liquid to a distal end of the sonotrode.
32. The instrument according to claim 31, wherein the liquid supply comprises a tube encompassing the sonotrode, the instrument being equipped to conduct the liquid through a space between an outer surface of the sonotrode and in inner surface of the tube.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0094] Exemplary embodiments of device and method according to the invention are described in further detail in connection with the appended Figures.
[0095] FIG. 1 shows in a schematic drawing a cross section of an exemplary embodiment of a sonotrode.
[0096] FIG. 2 shows in a schematic drawing a cross section of an exemplary embodiment of a sonotrode.
[0097] FIG. 3 shows the distal part of an ultrasonic surgical instrument for cutting bones including a piezoelectric stack located inside a housing with a sonotrode according to the invention at the tip of the housing.
[0098] FIG. 4 shows a schematic drawing of an exemplary embodiment of a sonotrode.
[0099] FIG. 5 shows in a schematic drawing a cross section of an exemplary embodiment of a sonotrode.
[0100] FIG. 6 shows in a schematic drawing a cross section of an exemplary embodiment of a sonotrode.
[0101] FIG. 7 shows in a schematic drawing a cross section of an implant which may be cut out using a sonotrode according to FIG. 5 or 6.
[0102] FIG. 8 shows in a schematic drawing an exemplary embodiment of a sonotrode with a slanting cut.
[0103] FIG. 9 shows in a schematic drawing an exemplary embodiment of a sonotrode with a parabolic cut.
[0104] FIG. 10 shows in a schematic drawing an exemplary embodiment of a sonotrode with a rim.
[0105] FIG. 11 shows in a schematic drawing an exemplary embodiment of a sonotrode with a rim.
[0106] FIG. 12 shows in a schematic drawing an exemplary embodiment of sonotrode within an arthroscopic tube.
[0107] FIG. 13 illustrates two examples of the sonotrode (B and C) according to the invention.
[0108] FIG. 14 shows a cross section of a sonotrode according to FIG. 13B located within an arthroscopic tube.
[0109] FIG. 15 shows the distal part of an ultrasonic surgical instrument.
[0110] FIG. 16 shows the cross section of an exemplary embodiment of a sonotrode.
[0111] FIG. 17 shows the distal part of an exemplary embodiment of a sonotrode.
[0112] FIG. 18 shows a longitudinal section of an exemplary embodiment of a sonotrode.
[0113] FIG. 19 shows a longitudinal section of an exemplary embodiment of a sonotrode.
[0114] FIG. 20 shows an exemplary embodiment of a sonotrode.
[0115] FIG. 21 depicts the distal part of a further with encompassing tube.
[0116] FIGS. 22-24 show, in longitudinal section and bottom view, distal ends of sonotrodes with interior blades.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0117] In all appended Figs., same reference numerals designate same elements or similar elements serving same functions.
[0118] FIGS. 1 and 2 illustrate each an embodiment of a sonotrode according to the first aspect of the invention. Shown is a cross section of the distal end piece 5 of the sonotrode. The distal end piece 5 is designed as a hollow elliptic cylinder being open at the very distal end by having a cylindrical body. The distal end piece can serve as a punch or hollow cutting device using mechanical vibration. Therefore, the very distal end of the punch or hollow cutting device may be flattened. The sonotrode or respectively the distal end piece may have lateral ribs 7. These ribs run along a longitudinal axis of the distal end piece and face inwardly from the body.
[0119] The sonotrode of FIG. 1 has four ribs 7. Each rib 7 is located inside of the distal end piece. It is preferred that these ribs 7 are evenly distributed, in particular the ribs 7 are located at points where the minor axis and the major axis of the elliptic cross section cut the circumference of the cross section or respectively the surface of the distal end piece. It is also possible that the ribs 7 may each be placed at points of the circumference located half the way between the aforementioned points. Each rib 7 may be radially upstanding (radially protruding, inwardly protruding in the depicted embodiment) to a constant height above the inner surface of the distal end piece. The cross section of the ribs can vary. Here the cross section of the ribs is nearly triangular, but it may also be nearly semicircular or rectangular. Nevertheless, it is generally preferred that no sharp edges at the ribs and at the transition between rib and surface of the sonotrode body exist.
[0120] The sonotrode of FIG. 2 has eight ribs 7. Four ribs 7a are located inside of the distal end piece body and four ribs 7b are located outside of the distal end piece body. In case that a sonotrode has several ribs, it has been shown to be advantageous that these ribs are placed symmetrically. It is preferred that the ribs 7 are located at the points the minor axis and the major axis of the elliptic cross section cut the circumference of the cross section or respectively the surface of the distal end piece. Each rib 7a may be radially upstanding (radially inwardly protruding) to a constant height above the inner surface of the distal end piece and in addition each rib 7b may be radially upstanding (radially outwardly protruding) to a constant height above the outer surface of the distal end piece. The sonotrodes according to FIGS. 1 and 2 are suitable to be used to treat spinal stenosis in particular to trim or remove bone spurs or synovial cysts.
[0121] FIG. 3 shows the distal part of an ultrasonic surgical instrument including a transducer, such as a piezoelectric stack 3 located inside a housing 2 with a sonotrode 1 at the tip of the housing. The sonotrode 1 has been attached to the housing 2 via its proximal end of the head. Therefore, the head may have a thread or a plug-in connector or bayonet coupling or other suitable coupling structure at its proximal end. The sonotrode 1 connected to the housing may have longitudinal ribs 7. The ribs 7 may be located only on the distal end piece of the sonotrode, as an alternative to extending to the proximal head of the sonotrode as shown here. The sonotrode 1 may be a sonotrode according to FIG. 1 or 2 having an oval or elliptic cross section. It may alternatively have a different hollow cross section. However, it is preferred that the cross section does not vary over the length of the sonotrode 1, i.e., that the sonotrode is cylindrical (in this text, generally “cylindrical” is not restricted to the shape of a rotational cylinder but pertains to any general cylinder the base of which is a closed curve. The direction of oscillation is indicated by arrow 11. The oscillation is thus a longitudinal oscillation.
[0122] FIG. 4 shows a schematic side view of a sonotrode arrangement including a piezoelectric stack 3 (not shown) located inside a housing 2 coupled to a sonotrode according to the second aspect of the invention. The head 9 of the sonotrode may be formed as a solid rod. At the distal end of the sonotrode head 9 follows an intermediate element 8, which may be a separate part or a main body when produced one piece with the blade 5. The sonotrode blade 5 and/or the intermediate element (if present) includes elongate holes 10 (through slits) in the direction of oscillation 11. In addition, the blade 5 may be tapered towards the cutting edge 12. The width of the blade is about 5 times the size of the diameter of the sonotrode head 9. The intermediate element or the main body may have a thickness of 5-12 mm at the point of connection to the sonotrode head 9, which thickness tapers down to 2-6 mm towards the cutting edge 12 of blade 5, of which the width may be between 10-60 mm.
[0123] The blade 5 may have a straight cutting edge 12. Nevertheless, the cutting edge is preferably formed having the contour of the area to be cut or stamped out. The intermediate element 8 is used to transfer the oscillation towards the blade and the cutting edge. The intermediate element thereby may be a booster. Alternatively, the arrangement does not include a separate intermediate element, but the structure thereof may be formed by a main body of the blade 5. In addition to serving as a booster or as an alternative thereto, the intermediate element or corresponding structure forming the blade main body may serve for the expansion of the width (see FIG. 5) and the transition to the form of the cutting edge.
[0124] FIGS. 5 and 6 each show each a schematic bottom views on the cutting edge 12 of a blade of an exemplary sonotrode according to the second aspect of the invention. Both blades are adapted to cut out (for a removal process) an implant as shown in FIG. 7. FIG. 7 shows a cross section of an implant to be removed with the aid of sonotrodes having blades as illustrated in FIGS. 5 and 6. The implant is a dual-anchor with two pin-shaped anchorage portions 13 and a stabilization portion 14 situated between the two anchorage portions 13, for example as taught in WO2010/045749. It may be used as a fusion device particularly suited for fusion of a human lumbar facet joint. The blade as shown in FIG. 5 is formed to have the contour of one half of the implant. This means the sonotrode has to be used twice (once on each side of the implant) to stamp out the implant after being implanted and ingrown into the bone. The blade as shown in FIG. 6 is formed to encompass at one lateral side a slightly more than half of the contour of the implant to be stamped out. Thus, it can be ensured that there is an overlap of the cuttings, when using the sonotrodes twice, once on each side.
[0125] FIG. 8 shows a sonotrode with a distal end piece being hollow and having a slanted cut. The distal end portion of the sonotrode is cut slantwise. Thus, the cutting edge 12 of the punch is located in a plane that forms an angle with the longitudinal axis 40 of the sonotrode. The distance d between the maximum and the minimum length of the distal end portion or the blade is less than 10% of the length of the resonator (the effective length of the vibrating part). FIG. 9 shows a sonotrode with a distal end piece having a parabolic cut 16 at the distal end.
[0126] FIGS. 10 and 11 show each an axial section of alternative distal end pieces of a sonotrode. The sonotrode according to FIG. 10 has a rim 17, i.e. a radially outwardly protruding feature that is for example flange-like. The rim 17 at the distal end of the sonotrode according to FIG. 11 bounds a depression. The depression consists of a groove 19, especially circumferential groove, which runs parallel to the rim 17. The area 18 proximal to the rim 17 and the groove 19 is elevated in regard to the groove 19 but low-rise compared to the rim 17, i.e., the outer diameter of the section 18 proximally of the groove is smaller than the outer diameter of the rim but larger than the outer diameter of the sonotrode at the axial position of the groove 19. The area 18 may be between 0.1 and 5 μm lower than the rim 17. The groove 19 may be between 0.2 and 5 μm lower than the area 18. The minimal depth of the area 18 is sufficient to adequately lower the friction compared to a situation in which no rim was present or in which the outer diameter proximally of the groove was the same as the outer diameter of the rim.
[0127] The rim 17 may also be formed with a curvature or parabolic. The (axial) width of the rim may be <1 mm and preferably between 0.2-0.5 mm. The rim 17 runs preferably perpendicular to the longitudinal axis of the sonotrode.
[0128] FIG. 12 shows in an axial section a distal part of a sonotrode 1 within an arthroscopic tube 20. The sonotrode can be moved in a distal direction relative to the tube 20. Within tube 20 is a lumen being all in all a lumen similar to a lumen as used for the optical instruments (camera) used within an arthroscopy. The sonotrode is equipped with a portion 21 of a larger cross section in a node position N. This larger cross section is caused by a ring around the sonotrode wall. This ring may be a polymeric ring or a ring made of the same material as the sonotrode.
[0129] The arthroscopic tube may include a supply 23 for a liquid, which may be used to cool the sonotrode, to fill the joint and/or to flush the operating side of the sonotrode. The liquid should be sterile and may be physiological saline solution.
[0130] FIGS. 13B and C are axial sections and show each a distal portion of a sonotrode, which is adapted to a selected vibration frequency to vibrate with a node position N. FIG. 13A illustrates the vibration of the sonotrode by showing the deflection in dependence on the axial position. N1 and N2 denote nodes.
[0131] An arthroscopic tube (not shown in FIGS. 13B and 13C) reaches distally to cover the distal end of the sonotrode 1. The sonotrode 1 is equipped with a portion 22 of a larger cross section in the node position N. The larger cross section is caused by a bulge of the wall of the sonotrode. The bulge may be an integral part of the sonotrode wall and can be formed as a ring around the sonotrode having a square cross section (FIG. 13B). Alternatively, there may be several rectangles sitting on one cycle around the sonotrode with some space between them. These rectangles can be arranged within a consistent interval on that circle. Instead of rectangles there may also be spherical bulges attached on one circle around the sonotrode. The circle is always located in a node position N.
[0132] FIG. 14 shows a cross section of the sonotrode according to FIG. 13B in the node position N1. The sonotrode 1 is located within an arthroscopic tube 20. As can be seen, four rectangle bulges cause a larger cross section of the sonotrode in the node position N. Between these bulges is space 61, which may serve as channel for a liquid (cooling/flushing). Alternatively, the liquid may flow through the lumen of the sonotrode 1 and the space 61 may be used to suck liquid and debris.
[0133] FIG. 15 shows the distal part of an ultrasonic surgical instrument including a transducer 3 located inside a housing 2 with a sonotrode 1 at the tip of the housing. The sonotrode 1 has been attached to the housing 2 via its proximal end of the head. The device may further include a sleeve 24 around the sonotrode 1, which sleeve may be connected to the housing. The sonotrode 1 may be any sonotrode according to an embodiment of the present invention. In many embodiments, it is preferred that the sonotrode is symmetrical. The sleeve may have a window at the distal end so that only a part of the sonotrode protrudes out of the sleeve. Therefore, the window is like a longitudinal cut starting at the distal edge and ending in a curve leveling off. Alternatively, the window is a like a cut cutting away a part of the cross section from the sleeve. The window of the sleeve 24 may be formed to shield at least the half of the sonotrode cross section at the distal end of the sonotrode.
[0134] FIG. 16 shows the cross section of an embodiment of a sonotrode according to the invention. This sonotrode is particularly suitable to be used during total disc replacement surgery. The sonotrode as shown in FIG. 16 may be used for preparation of a vertebral body before implantation of a disc replacement implant or artificial disc. It may also be used for removing the problematic or damaged disc and/or to clean the space between the vertebral bodies. The most commonly used total disc replacement designs have two plates. One attaches to the vertebrae above the disc being replaced and the other to the vertebrae below. The plates have an essentially planar level, side or area to come into contact with the vertebral body. Nevertheless, the vertebral body are not planar. Therefore, the surgeon may cut the vertebral body. It is preferred that the cross section of the sonotrode is (essentially) rectangular or has at least one planar side. These plates may have inclined teeth for generating stability. Therefore, the sonotrode may have structures 29 attached to the distal end corresponding to the inclined teeth of the plates. Alternatively, the distal end piece may have a cross section including structures 29 corresponding to such teeth. The structures 29 may be ribs attached to the sonotrode having a triangular cross section or the cross section of the sonotrode may include triangular bulges.
[0135] It is possible that the sonotrode may optionally include a sleeve 24 as described for the sonotrode shown in FIGS. 15 and 17.
[0136] FIG. 17 shows the distal part of a sonotrode 1. Around the sonotrode 1 is attached a sleeve 24. The sonotrode 1 may be any sonotrode according to an embodiment of the present invention. It is preferred that the sonotrode is located symmetrically within the sleeve. The sonotrode may have a symmetrical cross section. The sleeve may have a window at the distal end so that only a part of the sonotrode protrudes out of the sleeve. Alternatively, the sleeve may be completely or partly (concerning only a part of the cross section) retractable. The part of the sonotrode protruding out of the sleeve can be used to punch out bone.
[0137] FIG. 18 shows a longitudinal section of a sonotrode 1 according to the invention. It illustrates that behind a distance used for punching, structures 27 may be attached, which are suitable for rasping or scratching bone. They may further be suitable for cutting into bone by moving the sonotrode along a longitudinal direction. It is preferably possible to remove or ablate bone by back and/or forth movement (bidirectional movement in regard to the surgeon). As shown the structure 27 may include circumferential ribs which may have a triangular cross section or a rectangular cross section. Alternatively, these structure may be formed like spikes or may be helical.
[0138] FIG. 19 shows a longitudinal section of a sonotrode 1 according to the invention having a structure 27 that is stepped, for example by being formed by several ribbons (bands) of rectangular cross section being attached around the circumference.
[0139] FIG. 20 shows a further embodiment of a sonotrode suitable for the device according to the invention. The sonotrode is particularly suitable for creating a series of bone openings before being removed from the operation site, and for removal of bone tissue (in particular the complete bone fragments punched out) from the openings created using the device. Bone fragments 30 punched out of a bone opening created with the aid of the sonotrode 1 may be stored within the hollow sonotrode or a space within the sonotrode, which may be formed by an extended cross section of the sonotrode. Thus, the sonotrode may include a space suitable as depot for bone fragments 30 or bone debris. The sonotrode 1 may be designed as disposable item, suitable to create several bone openings within one operation side and store the resulting (stamped or punched out) bone fragments. After removal from the operation side the bone fragments may be used as sample for tests or as allogenic transplant material. The sonotrode may be thrown away (with or without the bone fragments) or may easily be cleaned. The embodiment may be designed so that the vibration of the sonotrode facilitates transport of the bone fragments 30 and retain them within the open space.
[0140] In another embodiment the bone fragments may further be transported using hydraulic pressure. Therefore, there may be a channel within the device suppling a liquid such as water from the handle to the sonotrode. This liquid flow can be stopped or reversed to generate negative pressure. Alternatively, the liquid may be used to transport (or eject) the bone fragment out of the sonotrode. The bone fragment can be ejected into the operation side and flush away using the liquid generally used to clean the operation side (e.g. from blood). When using this alternative, the liquid flow into the sonotrode is not stopped, but in the moment the sonotrode cuts into the bone the outflow of the liquid is stopped. Therefore, the pressure within the sonotrode increases and this pressure can be used to remove the bone fragment from the sonotrode. In case that a negative pressure is used to transport and store bone fragments punched out, the bone fragments are suctioned. This supports the process of breaking away the portion of the dense bone punched out. Therefore, it is possible to remove the bone within the cutting edge of the sonotrode in one piece and without less damage to the surrounding tissue.
[0141] The liquid fed through the instrument may further be used to cool the sonotrode and/or to rinse the operation side. A space between the sonotrode and a cannula or guide shaft may be used to suck liquid and debris of the bone out of the operational side.
[0142] A further embodiment of the sonotrode 1 for removal of bone tissue (in particular the complete bone fragments punched out) from the bone openings created using the sonotrode the sonotrode may be designed so that vacuum facilitates transport of the bone fragments 30 and retains them within the sonotrode 1. Therefore, there may be a suction port 30.1 communicating with an interior 42 of the sonotrode 1 for pulling out air and applying vacuum within the sonotrode. FIG. 20 illustrates two possibilities (in reality, often the sonotrode will only have one suction port). A first suction port 30.1 (first possibility) is laterally attached to the sonotrode head. A second suction port 30.2 (second possibility) communicates with a proximal end of the sonotrode. Especially, the suction port may be present in a connecting piece 31 that is coupled to the proximal end of the sonotrode 1 in an airtight manner but from which the sonotrode may be removed.
[0143] In embodiments, the suction port 30.1, 30.2 is attached to the sonotrode in a node position. A suction port 30.1, 30.2 comprised within the sonotrode head and perhaps the handle or housing has to be cleaned after each operation (each treatment of a patient). A suction port 30.1 integrated in the distal end piece of the sonotrode 1 has the advantage that it has not be cleaned in case the sonotrode is a disposable item or is easier to clean because it is very short and without bend structure. On the other side it is more expensive to include such a suction port in the sonotrode, in particular in case that it is a disposable item.
[0144] A vacuum as applied by a suction port may also be used to support or facilitate breaking away the portion of the dense bone punched out. Therefore, it is possible to remove the bone within the cutting edge in one piece and without less damage to the surrounding tissue. In FIG. 20, reference number 25 denotes dense bone tissue (cortical bone), and reference number 26 denotes cancellous bone tissue.
[0145] FIG. 21 illustrates the possibility of using a tube 20 or a sleeve for supplying a liquid, as explained referring to FIG. 24 hereinbefore, in combination with removing material via the interior 42 of the sonotrode. The liquid is supplied to the tube 20 and flows in the space between the tube and the sonotrode towards distally. It flows, together with any tissue/material flushed away, back through the sonotrode, as illustrated by the arrows. As mentioned referring to FIG. 14 hereinbefore, also the reverse arrangement is possible.
[0146] In approaches of this kind, the liquid is not only a cooling/flushing liquid but also serves for promoting the transport of tissue and debris material away from the operation site. To this end, a vacuum may be applied to the interior 42 of the sonotrode, for example by providing a suction port as explained hereinbefore.
[0147] In embodiments, it may be advantageous if the to-be removed tissue, especially dense bone tissue, is not only punched out of the live tissue but also broken up into smaller pieces, as a larger bone fragment 30 of the kind illustrated in FIG. 20 may plug up the transport path. FIG. 22 illustrates the sonotrode with at least one interior blade 51 that disintegrates bone fragments that are transported towards proximally relative to the sonotrode.
[0148] In a most simple design, such an interior blade just extends transversely across the interior of the sonotrode.
[0149] The interior blade (this pertains to all embodiments with an interior blade) may have a cutting edge that extends in a plane perpendicular to the axis of the sonotrode, or, often preferably, it may have a cutting edge that is not parallel to such plane but is curved and/or at an angle therewith, as illustrated in FIG. 22, for cutting more smoothly into the tissue.
[0150] In special embodiments, a plurality of interior blades is present in a staggered arrangement, with a first interior blade 51 distally and a second interior blade 52 that is at a different angular position (i.e., angularly offset) more proximally (at a distance d). This is schematically illustrated in FIG. 22 as well as, in bottom views, in FIGS. 23 and 24 for different interior blade geometries.
[0151] In embodiments that include braking up the to-be removed tissue into smaller pieces, the device that includes the sonotrode may be used as morcellator.
[0152] Of course, the approaches of FIGS. 20/21 and of FIGS. 22-24 can be combined. Also, combinations of either or both with the features described referring to the other embodiments, especially a distal outward protrusion and/or inwardly facing ribs, are possible and often advantageous also.
[0153] Embodiments that include supplying a liquid to the site where the sonotrode acts (operation site) may include using the effect of cavitation for targeted tissue treatment. Cavitation (the creation and implosion of small vapor-filled bubbles due to the pressure variations) may lead to a highly aggressive environment around the sonotrode. This may be used in a targeted manner for removal of tumors, etc. In view of this, the configuration of FIGS. 20-24 involving removal of tissue via the interior of the sonotrode may be advantageous by preventing tissue and debris from being spread around in an uncontrolled manner.
[0154] In embodiments, the effect of the stamping out (punching out) and cavitation can be supplemented by supplying an according chemical agent, for example a cytostatic, in the supplied liquid.
[0155] The distal end piece of the hollow sonotrode according to the invention may have ribs on its inner side. These ribs may run parallel to the longitudinal axis of the sonotrode and along the complete length or may be arranged only in a distal part. The ribs may alternatively run along paths different from parallel to the longitudinal axis, for example by along a helical or other curve on the inner side of the distal end piece of the sonotrode. The ribs or protruding spikes or alternative protruding elements attached to the inner side of the sonotrode may facilitate breaking away of bone fragments after introduction of the sonotrode into the dense bone. Therefore, the sonotrode or the complete device may be rotated, so that torsion is applied to the bone fragment within the sonotrode. Alternatively, slicing elements may be arranged within the tube or sonotrode. These elements are suitable for cutting or breaking the bone core into small fragments respectively bone debris which may be aspirate from the sonotrode. The slicing elements may be formed as thin blades (e.g., two, three, four or five blades), which are arranged in a way to meet one another at the central axis of the tube. The sonotrode may cut into the dense bone with its distal end and when cutting deeper into the bone the slicing elements chop the bone core into smaller fragments. The distal ends of the slicing elements or blades may be sharp and may be slanting.
