Abstract
An augmentation method is provided, wherein a thermoplastic augmentation element is subject to mechanical energy impact and mechanical pressure by a tool so that augmentation material of the augmentation element is liquefied and pressed into hard tissue to augment the hard tissue, wherein in at least one axial depth, the augmentation element is segmented as a function of the circumferential angle so that at this axial depth the circumferential wall of the initial opening in first regions is in contact with the augmentation element and in second regions is not in contact with the augmentation element.
Claims
1. A method of augmenting hard tissue and/or hard tissue replacement material method comprising the steps of: providing an initial opening in the hard tissue and/or hard tissue replacement material; providing a thermoplastic augmentation element and a tool; placing the augmentation element in the initial opening, placing the tool in contact with a face of the augmentation element and pressing the tool against the face while energy is coupled into the tool and while a periphery of a liquefaction interface of the tool and the augmentation element is within the opening; thereby liquefying material of the augmentation element at the liquefaction interface(s) to yield liquefied material; causing portions of the liquefied material to penetrate into structures of the hard tissue and/or hard tissue replacement material; allowing the liquefied material to harden and to thereby become augmentation material; and removing the tool; wherein at least one of the following conditions is fulfilled: a. in at least one axial depth, the augmentation element is segmented as a function of the circumferential angle so that at this axial depth the circumferential wall of the initial opening in first regions is in contact with the augmentation element and in second regions is not in contact with the augmentation element; b. in at least one axial depth of a resulting, augmented opening, the augmentation material is caused to be segmented as a function of the circumferential angle; c. in a resulting, augmented opening, the augmentation material is provided in at least two augmented regions axially spaced from each other, wherein between the two augmented regions there is a non-augmented region; d. the augmentation element does not have the symmetry of a rotational cylinder but is asymmetric with respect to rotation around any axis.
2. The method according to claim 1, wherein in the step of pressing the tool against the face, the tool is pressed into a distal direction.
3. The method according to claim 2, wherein the augmentation element is guided by an auxiliary element during the step of pressing the tool towards a distal direction.
4. The method according to claim 3, wherein the auxiliary element comprises a distal foot, wherein during the step of pressing the tool towards a distal direction, the auxiliary element is compressed between the tool and the foot, and wherein after the step of causing portions of the liquefied material to penetrate into structures of the hard tissue and/or hard tissue replacement material, the auxiliary element is removed.
5. The method according to claim 3, wherein the auxiliary element has a non-circular cross section, and wherein a sub-assembly consisting of the auxiliary element and the augmentation element has a circular cross section.
6. The method according to claim 3, wherein the auxiliary element forms at least 60° of an outer contour of a sub-assembly consisting of the auxiliary element and the augmentation element in a cross section perpendicular to a proximodistal axis.
7. The method according to claim 1, wherein the augmentation element comprises a plurality of separate augmentation element parts.
8. The method according to claim 1, wherein the tool is a sonotrode and wherein in the step of pressing while energy is coupled into the tool, mechanical vibration energy is coupled into the tool.
9. A method of augmenting hard tissue and/or hard tissue replacement material, comprising the steps of: providing at least one thermoplastic augmentation element; placing the augmentation element in contact with the hard tissue and/or hard tissue replacement material and causing mechanical energy to impinge on the augmentation element to liquefy at least portions of the augmentation element and causing liquefied augmentation material portions of the augmentation element to penetrate into the hard tissue and/or hard tissue replacement material; letting the liquefied augmentation material portions re-solidify; and removing a portion of the hard tissue and/or hard tissue replacement material and of the re-solidified augmentation material to yield an augmented opening, the augmented opening having surface portions of the hard tissue and/or hard tissue replacement material with the re-solidified augmentation material and having surface portions of the hard tissue and/or hard tissue replacement material without the re-solidified augmentation material.
10. The method according to claim 9, comprising, prior to the step of causing liquefied augmentation material to penetrate into the hard tissue and/or hard tissue replacement material, providing an initial opening of a geometry different from the geometry of the augmented opening.
11. The method according to claim 10, wherein the step of causing liquefied augmentation material to penetrate into the hard tissue and/or hard tissue replacement material comprises causing the liquefied material to penetrate into lateral walls of the initial opening, wherein the augmentation element has a non-circular symmetry.
12. The method according to claim 9, wherein the step of removing a portion of the hard tissue and/or hard tissue replacement material and of the re-solidified augmentation material is a step of making an opening in the tissue, at a surface of which opening a part of the augmentation material is present.
13. A method of augmenting hard tissue and/or hard tissue replacement material, comprising the steps of: providing an initial opening in the hard tissue and/or hard tissue replacement material; providing a thermoplastic augmentation element, and further providing a tool and an auxiliary element; placing the augmentation element in the initial opening, the augmentation element at least partially encompassing a guiding portion of the tool or of the auxiliary element, coupling a pressing force and energy into the tool and from the tool into the augmentation element while a portion of the augmentation element is within the opening and in contact with the hard tissue and/or hard tissue replacement material; thereby liquefying material of the augmentation element to yield liquefied material; causing portions of the liquefied material to penetrate into structures of the hard tissue and/or hard tissue replacement material and/or into structures of an element connected to the hard tissue and/or hard tissue replacement material; allowing the liquefied material to harden and to thereby become augmentation material; and removing the tool; wherein at least one of the following conditions is fulfilled: A. during the step of coupling a pressing force and energy into the tool, an outer protection element at least partially encompasses the tool and locally prevents the tool from being in contact with the hard tissue and/or hard tissue replacement material; B. the augmentation element is generally sleeve-shaped and comprises at least one indentation or hole in a sleeve wall; C. during the step of coupling a pressing force and energy into the tool, in a telescoping region a portion of the tool encompasses a portion of the auxiliary element or a portion of the auxiliary element encompasses the tool, wherein at least one of the tool and of the auxiliary element comprises at least one protrusion facing to the other one of the tool and the auxiliary element, whereby in the telescoping region a contact between the tool and the auxiliary element at locations different from the at least one protrusion is prevented; D. during the step of coupling a pressing force and energy into the tool, the tool is pressed towards the distal direction, and wherein the tool comprises a distal broadening forming an salient feature that prevents a contact between the tool and the hard tissue and/or hard tissue replacement material at locations proximally of the salient feature; E. prior to the step of coupling a pressing force and energy into the tool, the augmentation element is connected to the tool by an axial positive-fit connection, and during the step of coupling a pressing force and energy into the tool, the auxiliary element is pressed against a distal direction to activate the step of liquefying material of the augmentation element and to push portions of the liquefied material aside and into the structures of the hard tissue and/or hard tissue replacement material.
14. The method according to claim 13, wherein at least condition A. is fulfilled, wherein the protection element comprises a tap for cutting a thread.
15. The method according to claim 13, wherein at least condition B. is fulfilled, wherein the augmentation element is generally sleeve-shaped.
16. The method according to claim 13, wherein at least condition C. is fulfilled, wherein at a distal end of the tool any remaining gap between the tool and the auxiliary element has a width of 0.2 mm or less.
17. The method according claim 13, wherein at least condition E. is fulfilled, wherein the tool has a threaded outer surface portion, and wherein the threaded outer surface portion is encompassed by the augmentation element.
18. The method according to claim 13, wherein the energy is coupled into the tool in the form of mechanical vibrations.
19. The method according to claim 13, wherein the augmentation element is generally sleeve-shaped.
20. The method according to claim 13, wherein the auxiliary element comprises a guiding shaft, wherein during the step of coupling a pressing force and energy into the tool at least a portion of the augmentation element at least partially surrounds the guiding shaft and the tool is arranged proximally of the augmentation element at least partially surrounding the guiding shaft, wherein the tool comprises the protrusion facing radially inwardly towards the guiding shaft.
21. The method according to claim 20, wherein the protrusion is arranged at a distal end of the tool.
22. The method according to claim 20, wherein the augmentation element is sleeve shaped with at least a portion of the auxiliary element completely surrounding the guiding shaft, and wherein the tool is sleeve shaped with a distal portion completely surrounding the guiding shaft.
23. The method according to claim 22, wherein the protrusion is an inwardly facing ridge.
24. The method according to claim 20, wherein the protrusion is an inwardly facing annular ridge.
25. The method according to claim 20, wherein in the step of coupling a pressing force and energy into the tool, the tool is pressed towards a distal direction against a proximal end face of the augmentation element.
26. The method according to claim 20, wherein the tool has a tapered distal end surface.
27. The method according to claim 20, wherein the protrusion is one-piece with other portions of the tool.
28. The method according to claim 20, wherein the tool is a sonotrode and wherein the step of coupling a pressing force and energy into the tool comprises coupling mechanical vibration energy into the tool.
29. The method according to claim 25, wherein the auxiliary element has a distal foot forming a proximally-facing shoulder and, whereby the augmentation element is clampable between tool and the distal foot.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) In the following, ways to carry out the invention and embodiments are described referring to drawings. The drawings mostly are schematic. In the drawings, same reference numerals refer to same or analogous elements. The drawings show:
(2) FIG. 1 bone tissue with an initial opening;
(3) FIGS. 1a and 1b distal portions of opening forming sonotrodes;
(4) FIG. 2a-8 arrangements including a tool (namely, a sonotrode), an augmentation element and/or an auxiliary element for segmented augmentation;
(5) FIGS. 9a-20 concepts of augmentation with impact/energy minimization;
(6) FIGS. 21-25 concepts of deflecting mechanical vibrations for an augmentation process;
(7) FIG. 26 the concept of using radiation for coupling energy into the augmentation element; and
(8) FIG. 27 the concept of using electricity for coupling energy into the augmentation element.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
(9) FIG. 1 shows a portion of bone tissue of a living human or animal bone. For example, the bone tissue may be jawbone tissue or bone tissue of other regions of the skull or may be bone tissue of the spinal column, such as of a vertebral body, or may be bone tissue of an extremity, or of a bone of the thorax, or of any other part of the human or animal bone framework. The depicted bone tissue includes comparably dense cortical bone 201 along the bone surface and less dense trabecular or spongy bone 202. An initial opening 203 in which an implant—such as, for example, a bone screw or a suture anchor—is to be anchored has, for example, been made by drilling. Alternatively, the initial opening 203 may be naturally present or may have been caused otherwise, for example in the course of a surgical operation. An opening axis 204 is shown. In case the opening is made by drilling, the opening may have rotational symmetry with respect to the axis 204. Because of the relatively low mechanical load resistance of the trabecular bone, especially if the bone is osteoporotic or osteopenic, it is desirable to augment the mechanical stability of the bone tissue prior to the implantation of the implant. According approaches have been described in WO 2010/045 751 incorporated herein by reference.
(10) In accordance with a further, sixth, aspect of the invention, an initial opening 203 is made by a set-up in which a vibrating tool (sonotrode) or a counter element is also used as hole forming instrument.
(11) Referring to FIGS. 1a and 1b, firstly the option of using the tool (for example, sonotrode) as hole forming element is discussed. For the purpose of forming the initial opening 203, the forward (distally) facing portions of the sonotrode are accordingly shaped. During introduction of the tool, the tool is forced into a distal direction while vibrations are coupled into the tool, wherein the parameters of the vibration are chosen to cause the distal end of the sonotrode to be forced into the bone tissue to cause an opening that is cylindrical or that in cross section is ring-shaped. This may be combined with a subsequent augmentation step in a ‘rearward’ configuration as, for example, described in WO 2010/045751 incorporated herein by reference, or as described for some embodiments hereinafter. More specifically, after the forcing step is finished, the sonotrode is again subject to mechanical oscillations—with accordingly adapted energy and other parameters—while it is retracted. At this time, proximally of the most distal sonotrode portion an augmentation element is placed and is at least in part liquefied by the simultaneous retraction and vibration energy impact.
(12) FIGS. 1a and 1b show example of distal portions of a sonotrode 3. The distal portions include a distal broadening that forms a shoulder that is pressed against the augmentation element 1 in the augmentation step in which the sonotrode is subject to a pulling force, and the interface between the sonotrode (or, More particularly, the shoulder) and the augmentation element serves as the liquefaction interface. The distally facing portions of the sonotrode are equipped with a cutting edge 93 (FIG. 1a) and/or with a piercing tip 94 (FIG. 1b) configurations with a piercing tip 94 are especially suited in situations where the bone tissue is very weak and has little density and/or the diameter of the opening is comparably small.
(13) In accordance with a second option, the instrument by which the initial opening is made or extended is not the tool that is later used for coupling the energy required for liquefaction into the augmentation element, but is the counter element for applying the counter force (in a forward configuration where the tool is held towards a distal direction while energy is coupled into the augmentation element for liquefying material of it). The counter element 2 in this may be shaped for example like the shown in FIG. 1a, FIG. 1b and described hereinbefore referring to the tool.
(14) Alternatively, the step of forcing the counter element into the tissue may be carried out manually without any further energy source.
(15) In embodiments according to the second option, the energy coupled into the augmentation element may as an alternative to mechanical energy also be radiation and/or heat.
(16) For the forcing step and for the augmentation step, the vibration tool is coupled to a vibration source, in particular to a source of ultrasonic vibration (e.g., piezoelectric vibration generator possibly including a booster to which the tool is coupled) and the tool and is suitable for transmission of the vibration from the proximal tool end to the distal tool and, preferably such that a tool face—that faces to the proximal side and in contact with the augmentation element forms the liquefaction interface—vibrates with a maximal longitudinal amplitude. It is possible also to activate the tool to vibrate in a radial or in a rotational direction.
(17) For the augmentation step, it is preferable to work with a substantially constant output of vibrational power, i.e. with vibration (base vibration) of substantially constant frequency and amplitude, wherein the frequency is in the above named frequency range (preferably between 2 and 200 kHz, between 10 and 100 kHz, or between 20 and 40 kHz) and is a resonant frequency of the vibrating system, and wherein the amplitude is in the range of 10 to 50 μm, preferably 20-40 μm. For the forcing step, in particular in cases in which the hard tissue constitutes a relatively high resistance, vibrational modes as known from, for example, vibration assisted bone cutting are preferable. Such vibration modes usually include pulses of higher amplitude and possibly sharper profiles (e.g., rectangular profile or Dirac impulse) and are, for example, provided by modulating the amplitude of the base vibration to, for example, form pulses of higher amplitude and preferably by also sharpening the input wave form as compared with the base vibration and by matching the system's resonance frequency. The so created pulses can include one or several wave cycles of the base vibration each, and can be periodic with a modulation frequency preferably in the range of 0.5-5 kHz or they can be generated stochastically (in amplitude and modulation frequency) but in any case in phase with the system's resonance frequency. A means for producing stochastically occurring pulses is described in the publication U.S. Pat. No. 7,172,420, which is incorporated herein by reference. Therein the higher amplitude of the pulses is preferably greater than the base vibration amplitude by a factor of between 2 and 10.
(18) Alternatively, such pulses can be achieved by overlaying the base vibration or replacing it with a pulse excitation generated by a mechanical impulse generator (e.g., including a rotationally driven unbalanced mass or hammer). Therein the higher amplitude of the pulses is preferably again greater than the base vibration amplitude by a factor of between 2 and 10 and the pulse frequency which may be regular in the region of 20 to 200 Hz and in particular lower than the lowest resonance frequency of the vibrating system (e.g., undesired flexural vibration of the sonotrode). The low pulse frequencies are particularly important if material liquefaction during the forcing step is possible but is to be prevented as best as possible.
(19) If as described above two different vibration modes are to be used in the forcing and in the anchoring step, the vibration source to which the vibration tool is coupled during the two steps is to be equipped for selectively producing the two vibration modes and with switching means for switching the vibration source from one vibration mode into the other one.
(20) Referring to the following figures, methods of augmenting bone tissue of, for example, a configuration as shown in FIG. 1 are described. With reference to FIGS. 2-8, embodiments of segmented augmentation are described.
(21) A first example of an assembly for circumferential segmentation is depicted, in sections along different planes, in FIGS. 2a and 2b. FIG. 2c shows a view of the sonotrode 3 of the assembly, FIG. 2d shows a schematic view of the assembly in section in the initial opening during the process, FIG. 2e shows a variant of an augmentation element, FIG. 2f shows the augmentation element of FIG. 2e together with a specially adapted auxiliary element, and FIG. 2g shows yet another augmentation element. FIG. 2a shows a cross section in plane A-A of FIG. 2b.
(22) The assembly includes an augmentation element 1 that has two separate augmentation element portions 1.1, 1.2, a tool (sonotrode) 3, and an auxiliary element 2 serving as counter element. The auxiliary element forms a guiding shaft 5 and a distal broadening 6 that forms a shoulder so that the augmentation element is capable of being compressed between the sonotrode 3 and the shoulder 6 during the process. The guiding shaft in the depicted embodiment in other word forms part of a counter element that in addition to the guiding element shaft includes a distal broadening 6 with proximally (rearwardly) facing counter element contact faces through which a counter force is coupled into the augmentation element portions. The counter force is a force of equal magnitude but opposite direction to the force by which the sonotrode is pressed against the augmentation element portions.
(23) The guiding shaft 5 does not have the shape of a rotational cylinder but is circumferentially structured to include two axial grooves in which the two augmentation element portions 1.1, 1.2 are placed. The sonotrode 3 is correspondingly segmented to include two pushing portions 3.1, 3.2 with a cross section approximately corresponding to the cross section of the augmentation element portions 1.1, 1.2. The sonotrode also includes a central cannulation 3.7 for the shaft portion 5 of the auxiliary element 2.
(24) In alternative embodiments, the auxiliary element may lack the distal broadening and merely be a guiding pin. In these embodiments, the counter force opposite to the sonotrode pressing force may be exerted by the tissue against which the augmentation element is pressed, or an adhesion and/or friction force by which the augmentation element portions adhere to the guiding element, or a combination thereof. In addition or as an alternative, it is also possible to provide the shaft and the augmentation element with surface structure engaging with each other, such as small indentations of the shaft into which corresponding inner protrusions of the augmentation element protrude.
(25) The segmentation of the augmentation element as illustrated with respect to FIGS. 2a and 2b may be over the full axial length of the augmentation element portions, or it may be partial, i.e., the segmentation my be restricted to certain axial positions whereas in other axial positions the augmentation element may include a portion 1.8 that surrounds the guiding shaft, so that the augmentation element is one-piece. A first according example is shown in FIG. 2e, where the shaft surrounding portion 1.8 is at the proximal end of the augmentation element. By the construction of the augmentation element shown in FIG. 2e, towards the distal end of the augmentation element there are open gaps between the element portions 1.1, 1.2. This may optionally be combined with an auxiliary element having a distal end that has according projections 5.2 as illustrated in FIG. 2f that prevent liquefied portions of the thermoplastic material to be spread into circumferential directions and. More particularly, the dimensions of the open gaps and the projections 5.2 may be adapted to each other so that the distance d.sub.1 is smaller than or approximately equal to the distance d.sub.2.
(26) Yet another embodiment of an augmentation element with portions 1.1-1.5 held together by a shaft surrounding portion 1.8 is shown in FIG. 2g. In this embodiment, the shaft surrounding portion is in an axially central position. Also the embodiment of FIG. 2g may optionally be used together with an auxiliary element of the kind depicted in FIG. 2f.
(27) In FIG. 2b a proximodistal axis 4 is also depicted. In the configuration of FIGS. 2a-2g, the elements 1, 2, 3, of the assembly do not have circular symmetry around this axis.
(28) For carrying out the method with segmented augmentation, the assembly of FIGS. 2a and 2b is placed in the initial opening with the axis 4 approximately parallel to the opening axis 204. Then the sonotrode 3 is pressed towards the distal side while mechanical oscillations are coupled into the tool and while the auxiliary element is held against the pressing force so that the augmentation element is compressed between the vibrating sonotrode and the auxiliary element. The vibration energy is chosen to be sufficient so that a melting process of the thermoplastic auxiliary element material sets in the forward movement of the sonotrode (and/or the rearward movement of the auxiliary element) causes the molten thermoplastic material to be pushed aside and into structures of the surrounding cancellous bone tissue. This is illustrated in FIG. 2d. The displaced thermoplastic material portions 11.1, 11.2 re-solidify and thereby augment the bone tissue. The process is, for example, continued until all augmentation element material has been liquefied and displaced and until the distal end faces of the pushing portions abut against the shoulder 6 formed by the distal broadening.
(29) Because the augmentation element is segmented, i.e. includes two augmentation element portions at different angular positions with respect to the proximodistal axis, the thermoplastic material portions 11.1 remain separate and form two augmentation regions.
(30) Whereas referring to FIGS. 2a-2d circumferential segmentation of the augmentation element has been described referring to a configuration to augment a circular hole and using two segmentation element portions in a symmetrical arrangement, various other embodiments are possible. For example, the two segmentation element portions need not be arranged symmetrically with respect to a symmetry plane as the illustrated embodiment, but other, asymmetrical arrangements are possible. Further, more than two segmentation element portions may be used (as, for example, in the lower part of the augmentation element of FIG. 2g), for example three, four, five, six or even more—all in a symmetrical or asymmetrical arrangement. Also, the augmented initial opening need not be circular but can have any other shape.
(31) A further example of segmented augmentation is described referring to FIGS. 3a-4. This example uses the insight that the augmentation process does not rely on circular symmetry of the opening to be augmented. Rather, it is possible for mechanical energy capable of liquefying the thermoplastic augmentation element also in non-circular arrangements.
(32) FIG. 3a shows, in cross section along plane A-A in FIG. 3d, a guiding shaft 5 of an auxiliary element, and an augmentation element 1 surrounding the guiding shaft 5. The guiding shaft and the augmentation element have a translational symmetry along the proximodistal axis and a generally triangular shape in cross section. The sonotrode 3 is proximal of the augmentation element and has a portion with a similar shape.
(33) For augmentation, in a first step, the assembly of FIGS. 3a and 3d is placed in the initial opening. Then the sonotrode 3 is pressed towards the distal side while mechanical oscillations are coupled into the tool and while the auxiliary element is held against the pressing force so that the augmentation element is compressed between the vibrating sonotrode and the auxiliary element and so that at the interface between the sonotrode and the augmentation element the thermoplastic material of the augmentation element starts melting and is displaced into the surrounding bone tissue. The result is illustrated, again in section, in FIG. 3b. The initial opening, that is triangular in cross section, is surrounded by an augmented region where the bone tissue is interpenetrated by the augmentation material 11. The dashed line 21 in FIG. 3b shows where in a next step a bore is added. The bore 23 has a circular cross section and is thus suitable for implanting, in a subsequent step (not shown) a surgical screw. When the bore is made, further bone tissue as well as regions of the augmentation material are removed. What remains (FIG. 3c) is bone tissue that is augmented in the regions where the augmentation material is not removed. FIG. 3c illustrated three separated augmentation material portions 11.1, 11.2, 11.3. The lobes 25 that may optionally remain at the edges of the initial opening may add further flexibility and may soon after implantation of the surgical screw (or other implant) be filled by tissue.
(34) As an alternative to being triangular, the initial opening and the augmentation element in variants of this group of embodiments may have other non-circular cross sections. An example of such an alternative is illustrated in FIG. 4, schematically in section perpendicular to the proximodistal axis. The initial opening and the augmentation element 1 have a generally elongate cross section, so that after augmentation and adding the bore (dashed line 21) two augmented regions will remain. Various other non-circular shapes are possible, both, symmetric and asymmetric. In particular, it is possible to adapt the shape to the anatomy of the place where the implant is to be anchored.
(35) The approach of FIG. 4 can be implemented both, in forward configurations with a sonotrode 3 that is pushed during the augmentation process (as illustrated in FIG. 3d) and in “rearward” configurations in which the sonotrode is pulled, as for example described in WO 2010/045 751. In “rearward” configurations, further in accordance with the sixth aspect, the sonotrode may optionally have a cutting distal edge that allows manufacturing the initial opening by introduction of the sonotrode while mechanical energy is coupled into the sonotrode.
(36) With reference to FIGS. 5a and 5b yet another possibility to provide segmented augmentation is depicted. FIG. 5a shows a section along the proximodistal axis, whereas FIG. 5b shows a view onto the tissue surface. In accordance with this possibility, the sequence of steps is reversed. As a further difference to the previously described embodiments, an auxiliary element with a guiding shaft is not required. Instead, a plurality of pin-like augmentation elements 31 are implanted in a first step. To this end, an according number of bores (initial openings) may be prepared, whereafter the pin-like augmentation elements 31, which consist of the thermoplastic material, are implanted. The pre-made bores may as an option have a depth that merely corresponds to the depth of the cortical bone tissue, i.e., the preparation then only includes locally removing the cortical bone. Alternatively, the pre-made bores may have a larger depth, or in case of weak bone or already-removed cortical bone, the augmentation elements may be directly driven into the bone tissue without any prior additional removal of bone tissue. Concerning the process of driving implants (here serving as augmentation elements) of thermoplastic material into bone tissue, it is referred to WO 02/06981 the content of which is incorporated herein by reference in its entirety.
(37) The augmentation elements are implanted along the contour 32 of a bore 33 that is made subsequently to implanting the augmentation elements. The bore may be conical or have another shape with a cross section that diminishes as a function of the dept. More particularly, the cross section at the bone surface is such that the augmentation element is within the bore (dashed line 32 in FIG. 5b), and the cross section at the distal end of the bore (dotted line 34 in FIG. 5b) is such that at least part of the augmentation elements is outside of the bore. By this, not only a circumferential segmentation may be achieved but also a restriction of the augmented region to the deeper part of the bore so that for example no augmentation material reaches the top. This may be desired to make possible that after healing the cortical bone can be contiguous around the implant.
(38) FIGS. 5c and 5d yet depict two versions of a guiding tool 121 for preparing bores for the augmentation process of FIGS. 5a and 5b. The tool 121 has a body 122 that in the depicted embodiments is essentially disk-like. The body has per augmentation element a guiding opening 123 for guiding a drill that pre-makes the holes and/or that guides the pin-like augmentation elements and sonotrode during the insertion of the augmentation elements. The tool may further include a holding structure 124 such as one or more spikes that secures the tool 121 against lateral movements. The embodiment of FIG. 5d further includes a central through opening 125 for the drilling of a centering bore for the later conical bore.
(39) Whereas this embodiment has been described with a conical bore or a bore that has an otherwise tapering shape, the concept of implanting an augmentation element or a plurality of augmentation elements along a contour of a bore made subsequently may also be applied to cylindrical bores. In these embodiments, the outer contour of the bore should go through the implanted augmentation elements.
(40) It is further also possible to combine a cylindrical bore with pin-like augmentation elements that are not implanted parallel to the proximodistal axis but radially outward (so that the distal end points away from the proximodistal axis). By such configuration, a similar effect as the one of the depicted embodiment may be achieved.
(41) In the shown embodiment, two pin-like augmentation elements 31 are shown, however, the concept may also be realized with one or with more than two augmentation elements. Generally, a plurality of augmentation elements may be arranged in a symmetrical or in an asymmetrical configuration.
(42) The effect of restricting the augmentation material to deeper regions of the bore by means of a tapering bore may also be used in configurations in which the augmentation material is applied by a method as described referring to FIGS. 1-4 or by variants thereof without segmentation (but, for example, with a tube-shaped augmentation element, including ‘rearward’ configurations as described in WO 2010/045751 incorporated herein by reference).
(43) FIG. 6 shows, in cross section along the proximodistal axis, a configuration where an initial opening 203 of for example cylindrical shape has been augmented so that augmentation material portions 11 strengthen the bone tissue. This augmentation may be a segmented augmentation where the segmentation material is confined to certain angles around the circumference—for example as taught referring to previous figures—or may be a non-segmented augmentation where the augmentation material is distributed around the periphery. Subsequently, tissue and material may be removed along the dashed line 33 so that the augmented bone surface becomes restricted to the deeper regions of the opening.
(44) Circumferential segmentation and depth dependence of the augmentation may be combined. An example is illustrated in FIGS. 7a-7c. The initial opening is stepped and has a large diameter proximal portion and a smaller diameter distal portion so that a shoulder 111 is formed. The guiding shaft 5 in cross section has a shape as illustrated in FIG. 7c. FIGS. 7a and 7b correspond to cross sections along planes that in the section only through the guiding shaft (FIG. 7c) correspond to the lines A-A and B-B, respectively. The augmentation element has first augmentation element portions 1.1, 1.2 that are positioned around at the periphery and that during the method step of liquefying are pressed against the shoulder. Second augmentation element portions 1.3, 1.4 are located distally in the channels 5.1 of the guiding shaft. During liquefaction, they are pressed against the bottom of the initial opening. The shape of the sonotrode 3 is accordingly adapted. As an alternative to the depicted configuration, the auxiliary element may include abutment protrusions that axially extend from the guiding shaft proximally of the shoulder 111 and/or a distal broadening of the kind illustrated in FIG. 2b so that the counterforce to the pressing force is not exerted by the tissue but by the auxiliary element.
(45) FIG. 8 shows yet another example of segmented augmentation, again in cross section parallel to the proximodistal axis. The embodiment of FIG. 8 may combine axial segmentation (i.e. augmentation at different depths) with circumferential segmentation. In the embodiment of FIG. 8, the initial opening is tapered, it is for example conical. The auxiliary element 2 has an accordingly tapered shape. For the augmentation process, it is to be placed in the initial opening, with a circumferential wall and possibly a distal end in contact with bone tissue as shown in FIG. 8. The auxiliary element is a body with openings accessible from the proximal side. Between the openings and the circumferential wall, there are holes. For example, a larger, central opening 41 includes a plurality of holes 43 distributed regularly or irregularly around the periphery. Smaller, peripheral openings, for example, each include a lateral hole 43. The peripheral openings 42 may be distributed regularly or irregularly along the periphery. It would also be possible for the auxiliary element to include a single peripheral opening only. The augmentation elements 1 may, for example, be pin-shaped, with an outer diameter adapted to the dimension of the opening they are provided for. During the augmentation process, augmentation elements 1 are inserted in the openings and pressed towards the distal direction while mechanical energy impinges on the respective augmentation element. Thereby, the augmentation material at the distal end of the augmentation elements is liquefied and pressed out of the holes into the surrounding tissue. The auxiliary element may be removed after liquefaction of the augmentation material; for example, removal may be made immediately after the offset of the mechanical energy input (for example the vibrations) so that the augmentation material is still soft in vicinity to the auxiliary element. As an alternative, a cutting element may be used for removing the auxiliary element; such cutting element may for example be a feature (proximally facing cutting edge or similar) adjacent to the holes 43 that cuts through the augmentation material portions that are at the interface between the auxiliary element 2 and the bone tissue.
(46) In addition or as an alternative to the openings 41, 42, the auxiliary element—that may be viewed as guiding tool for individual augmentation elements 1 may have indentations (openings) along the circumferential surface. After an augmentation process using such an auxiliary element, thermoplastic augmentation material portions may protrude into the conical opening and thus need not be restricted to the bone tissue. Such embodiments are especially advantageous in situations where the subsequent implantation of the implant involves welding thermoplastic material of the implant to the augmentation material or involves an implant with a surface structure into which, when the augmentation material during implantation is again liquefied, again thermoplastic material may penetrate to generate a positive-fit connection. The principle of a positive-fit connection between a thermoplastic part (here: the augmentation element) and a non-liquefiable part having according structures is, for example, described in WO 2008/034 276 incorporated herein by reference; especially the basic principle is shown referring to FIGS. 1-7.
(47) Next, embodiments of the aspect of impact/energy minimization are described. In these described embodiments, the energy coupled into the set-up during the process is mechanical vibration energy and the tool is a sonotrode. However, the concept can readily be expanded to other energy forms, including other mechanical energy (for example rotation), heat, electromagnetic radiation.
(48) FIGS. 9a and 9b, in cross sections parallel to the proximodistal axis, show a first approach. It has been found that substantial noise and also possibly energy losses are caused by the contact between the sonotrode 3 and the guiding shaft 5 of the auxiliary element in configurations where the sonotrode and possibly also the augmentation element is/are guided by the guiding shaft. The region where the tool (sonotrode) and the auxiliary element slidingly overlap is also denoted “telescoping region” in the present text.
(49) In FIGS. 9a and 9b, the inner diameter of the sonotrode is larger than the outer diameter of the guiding shaft so that a buffer volume 52 is formed around the guiding shaft. The sonotrode includes an inward projection 51 at the distal end thereof. The inward projection is, for example, an inwardly projecting ridge forming a contact surface in direct contact with the guiding shaft. The contact surface fully encompasses the shaft forming a sealing for liquefied material preventing the latter from penetrating into the buffer volume.
(50) In the embodiment of FIG. 9a, the distal end face of the sonotrode that forms the contact with the augmentation element 1 is essentially flat and radial with respect to the axis, whereas the embodiment of FIG. 9b has a tapered sonotrode surface that helps to push the liquefied augmentation material outward into the surrounding tissue. In all embodiments, the contact face between the sonotrode and the augmentation element may generally have any shape, including flat, curved, tapered etc.
(51) In the shown embodiment, the inward projection 51 is one-piece with the rest of the sonotrode. In alternative embodiments, a separate part—that can be viewed as a bushing—may be used. The use of such separate part may be advantageous, especially since a suitable material may be used. Such suitable material may be chosen so that it minimizes the sonotrode impact while it is not necessarily a good conductor for ultrasonic vibrations. An example of a suitable material for a bushing is PEEK; alternatively other polymer materials that have a comparably small friction coefficient to steel, such as PTFE, PA, etc. or other plastic or non-plastic materials may be used.
(52) As a further option, the inward projection, especially if formed by a separate part (bushing), could include a small circumferential scraping lip in contact with the guiding shaft. As an alternative to such a scraping lip, also a corresponding fit allowing for a relative movement, such as a transition fit etc. may be used, especially for a hard-soft material combination between guiding shaft and projection/bushing 51.
(53) In addition or as an alternative to the above-discussed variants, the buffer volume 52 may be partially or entirely filled by a material with reduced friction/noise development between the shaft and the vibrating (or directly heated or energy conducing) parts. Such material then may serve as a kind of inner liner; the material may for example be a polymer such as PEEK, PTFE, PA, etc.
(54) FIG. 10 depicts, in cross section perpendicular to the proximodistal axis, an embodiment where the sonotrode includes inwardly projecting axial ribs 54 so that again the contact surface between the sonotrode and the guiding shaft is diminished. This may optionally be combined with a distal inwardly projecting ridge as shown in FIGS. 9a, 9b. FIG. 11 (in cross section parallel to the proximodistal axis) similarly shows a configuration with inwardly projecting circumferential ribs 55. Again, a combination with the distal ridge is possible. Alternatively, instead of ribs or in addition thereto the sonotrode may include other inward projections such as humps etc.
(55) FIGS. 9a-11, as well as FIGS. 17 and 18 described hereinafter, show examples of configurations where the area of the surface between the sonotrode and the auxiliary element is considerably reduced compared to configurations where the sonotrode is a cylindrical sleeve surrounding a cylindrical shaft. More particularly, in the telescoping region the contact surface is substantially (for example by at least a factor 2) smaller than the outer surface area of the auxiliary element in that telescoping region.
(56) Another group of approaches for impact minimization, which may be combined with the approach of diminishing the direct contact between sonotrode and guiding shaft, is shown in FIGS. 12-15. The embodiments of these figures all include the concept that the augmentation element is shaped in a manner that causes the augmentation element, or at least portions thereof, to be liquefied with less energy impact, i.e., onset as a function of the energy that impinges on the augmentation element is earlier. This allows to reduce the power of the energy source, for example the power by which the sonotrode is operated.
(57) The cross sections of FIGS. 12 and 13 show a section of a generally rotationally symmetrical arrangement, with the symmetry axis (not shown) through the guiding shaft 5. The augmentation element 1 of FIG. 12 includes outer and inner grooves 61, 62, respectively, whereas the augmentation element of FIG. 13 has inner grooves 62. The grooves systematically weaken the augmentation element and, by causing necks, provide spots where the liquefaction upon absorption of the mechanical energy sets in first. Further, the inner grooves 62 of the embodiment of FIG. 13 are slanted towards the outside so that after onset of liquefaction at the necks the more proximal portions slide on the more distal portions and are forced outwardly, so that additional friction of not yet liquefied augmentation material with the lateral walls of the initial opening and/or an additional pressure onto the liquefied material is caused, both effects potentially assisting the augmentation process. A similar effect could be achieved by outer grooves that run along same conical surfaces as the illustrated embodiments, i.e. the grooves are such that after a liquefaction at the weak spots (necks) the more proximal parts of the augmentation element are subject to a shear movement that forces them outwardly when they are subject to pressure from the sonotrode 3. In both variants (and in combinations), an additional axial division (not shown in FIG. 13) or a circumferential segmentation as illustrated in previous embodiments may ensure sufficient flexibility for such an outward movement.
(58) The grooves 61, 62 of the embodiments of FIGS. 12 and 13 or similar weakenings of the augmentation element 1 may also be chosen for not rotationally symmetrical arrangements, such as arrangements that include segmentation in accordance with any one of the embodiments described hereinbefore.
(59) The embodiments of FIGS. 14 and 15 show views of other variants of systematically weakened augmentation elements. The embodiment of FIG. 14 includes an augmentation element 1 having generally a shape of a rotational cylinder with a plurality of through holes 63. In the depicted embodiment, the through holes are arranged in axial rows. Generally, the position and distribution of holes or other weakenings of the augmentation element may be chosen according to the needs.
(60) In the embodiment of FIG. 15, the augmentation element 1 having generally a shape of a rotational cylinder includes elongate axial holes 64. The axial extension of such holes may be such as to correspond to a substantial portion (for example, at least ½ or even at least ⅔) of the axial length of the augmentation element 1. The axial holes, in addition to reducing the power requirements of the mechanical (or other) energy impact, may have the effect of causing a weak circumferential segmentation. The extension (along the circumferential direction) and the distribution of the axial elongate holes 64 may be chosen accordingly. In the depicted configuration, the augmentation element further includes bridge portions 65 that form bridges over the elongate holes, for example approximately in their middle, to enhance the mechanical stability of the augmentation element. Especially if a circumferential segmentation effect of the augmentation material is desired, the bridge portions 65 may have a minimal material strength only; for example, they may be thinner than the body of the augmentation element.
(61) The embodiment of FIG. 16 (shown in section) includes a sonotrode 3 with an outwardly protruding (salient) distal feature 71 such as a circumferential ridge. Due to this shape, the sonotrode has a reduced thickness at more proximal positions so that it does not get into direct contact with the bone tissue proximally of the distal feature 71. This significantly reduces the impact, especially frictional heating of the adjacent bone tissue. The same applies if the tool 3 is not a sonotrode but a heating element or a rotating element.
(62) An outwardly protruding distal feature of the kind illustrated in FIG. 16 may be realized in embodiments with a tapering contact face of the sonotrode to the augmentation element (as shown in FIG. 16), in embodiments with a flat contact face, or in combination with any other contact face shape. Combinations with the approaches of any one of the previous figures, including minimization of the contact surface between sonotrode and guiding shaft as illustrated in FIGS. 9-11 are possible.
(63) Another possibility of minimizing the sonotrode impact, especially the noise created by friction between sonotrode and guiding shaft, is shown in section in FIG. 17. The sonotrode in this embodiment includes a plurality of inwardly facing micro-protrusions 81. The micro-protrusions, which may be conical or calotte shaped or have other shapes, abut against the auxiliary element 2 guiding shaft and thereby cause the contact surface between the sonotrode 3 and the guiding shaft to be minimal. The micro-protrusions 81 have a height that is comparably small so that the resulting gap between the shaft and the sonotrode has a thickness d that is so small that due to surface tension substantially no liquefied thermoplastic material will penetrate into the gap. More particularly, the gap thickness d (approximately corresponding to the height of the protrusions) may be between 0.02 mm and 0.2 mm. In a gap having a thickness of this order of magnitude, no thermoplastic material will penetrate.
(64) Whereas FIG. 17 shows the micro-protrusions being inwardly protruding features of the sonotrode, it would also be possible to provide according outwardly facing protrusions of the guiding shaft.
(65) As an alternative to micro-protrusions that define punctiform contact surface portions, it would also be possible to have ridge-shaped micro-protrusions 82 as illustrated in FIG. 18. The embodiment of FIG. 18 includes the micro-protrusions 82 at the guiding shaft; of course, according (inwardly facing) ridge-shaped micro-protrusions may also be present at the sonotrode. The radial dimension of the protrusions of FIG. 18 may again be in the range between 0.02 mm and 0.2 mm.
(66) Next, referring to all embodiments of the various aspects of the invention, some considerations on augmentation element dimensions, especially wall thickness are made. The thickness primarily depends on the desired infiltration depth (penetration depth), and on the porosity of the bone. First assuming that the augmentation element is tube-shaped and the radius of the augmentation element is much larger than the wall thickness—so that a plane configuration can be assumed in approximation, for an infiltration depth of 1 mm and a porosity of 40% (healthy bone in the present model), the wall thickness is 0.4 mm. For a porosity of 80% (osteoporotic bone in the present model), one gets a wall thickness of 0.8 mm for a penetration depth of 1 mm, and for a porosity of 60% one obtains 0.6 mm wall thickness. In the present approximation, the wall thickness is a linear function of the penetration depth, so that for example for a penetration depth of 2 mm and a porosity of 80%, the wall thickness has to be 1.6 mm. In these considerations, it is assumed that the material flow is ideal and that all augmentation element material is displaced into the bone tissue. In reality, this is not the case. Rather, the bone tissue promotes a freezing behavior of penetrating thermoplastic material, which freezing behavior is the more pronounced the denser the bone tissue. This effect can be taken into account by replacing the real, measured porosity by a reduced apparent porosity. The apparent porosity can be measured by the following process: Augmentation using a simple augmentation cylinder of given wall thickness d.sub.w (for example 0.5 mm) in spongy bone, for example a pig's femoral condyle, complete displacing in penetration Measuring of an average penetration depth d.sub.m and a penetration height h.sub.m (corresponding to the axial extension of the augmented bone tissue portion) Calculating a correction factor F=d.sub.m/d.sub.t*h.sub.s/h.sub.m where d.sub.t denotes the theoretical penetration depth in accordance with the above considerations for ideal material flow and h.sub.s is the original height of the augmentation element, and Calculating an apparent porosity P.sub.A to be P*F.
(67) In an example measurement with P=35%, the values of d.sub.m/d.sub.t=0.6 and h.sub.m/h.sub.s=0.9 have been obtained, so that F=0.667. For a porosity of 40% and a penetration depth of 1 mm one then obtains a wall thickness of 0.267 mm. The wall thickness is again proportional to both, the penetration depth and the porosity, so that starting from this value other wall thicknesses can be calculated.
(68) If not all augmentation material is displaced into the bone tissue, residual wall thicknesses of material remaining within the augmented opening are to be added to the wall thickness.
(69) In cases of segmented augmentation and/or augmentation elements with openings, along the axially running edges there will be additional material flow in circumferential directions to some extent. As a rule, polymer flow will broaden the augmented region (in circumferential direction) by about 0.5-1 mm. Thus, at these regions there will be an accordingly reduced infiltration depth. This is clinically not critical. Especially in dental medicine this will result in a reduced potential exposure of sensitive structures.
(70) FIG. 19 shows, again in section, yet another approach of sonotrode impact minimization. In the embodiment of FIG. 19, the sonotrode 3 includes a sonotrode shaft 91 that is, at more proximal axial positions, encompassed by the auxiliary element 2 having the shape a sleeve. The augmentation element 1 is held by the sonotrode, for example in an interlocking connection. For example, the sonotrode 3 may have an outer thread, and the auxiliary element may be screwed onto the sonotrode. In the depicted configuration, the sonotrode has an—optional—distal broadening 92 (foot) that is an additional support securing the augmentation element against escaping in a distal direction. During the augmentation process, the sonotrode with the augmentation element affixed to it vibrates while the sleeve-like auxiliary element is pressed against the proximal surface of the augmentation element. At the interface between the sonotrode and the sleeve-like auxiliary element, mechanical energy is absorbed causing the augmentation element material to partially liquefy. During the process, for example the sonotrode's axial position may be held still while the auxiliary element 2 is pressed forward.
(71) The embodiment of FIG. 19 features the advantage that due to the configuration with the central sonotrode and the peripheral auxiliary element, there is only minimal contact between the sonotrode and the tissue surrounding the initial opening.
(72) An assembly corresponding to the one of FIG. 19 would also be possible in a ‘forward’ arrangement where the contact face between the augmentation element and the auxiliary element is at the distal end of the augmentation element. In such an assembly, the auxiliary element may for example have a thin shaft carrying a distal foot (that includes the contact face), the shaft reaching through the sonotrode. While such a configuration is a possibility, the configuration of FIG. 19 has the additional advantage of being more straightforward to implement.
(73) Further, optionally, the distal end of the sonotrode could be provided with a cutting or piercing functionality, for example according to the sixth aspect of the invention. Such a piercing or cutting feature could for example work as a optionally vibration assisted awl when introducing the assembly in the tissue—the initial opening does then not need to be pre-made in a separate step but can be made by introducing the assembly.
(74) FIG. 20 shows in section an embodiment including a protecting element 96. The protection element at least partially encompasses the sonotrode 3 and thereby protects the bone tissue. The protection element 96 may include a distal cutting/reaming structure and/or a tapping structure to provide the augmented or not augmented bone tissue with a thread.
(75) In the depicted configuration, the protecting element 96 is shown in combination with a stepped opening. This is not a requirement; sufficiently thin (<0.1 mm or 0.05 mm) protecting elements of sufficiently stiff material (for example steel) may also be used together with not stepped openings. A stepped opening may be provided in that the initial opening is made in a stepped fashion (for example using two drills of different diameters), or by a self-cutting structure of the protecting element itself, that then may for example also advance during the augmentation process to prevent all of the sonotrode with the possible exception of the most distal portion from getting into contact with the bone tissue.
(76) A protecting element 96 could optionally be segmented in a circumferential direction and then optionally project further to the distal side, for example down to the bottom of the opening. Thereby, it locally masks the bone tissue and causes segmented augmentation. In this variant, the set-up of FIG. 20 is a further embodiment of the method according to its first aspect.
(77) In an even further embodiment, a protecting element 96 serving as a mask could have a geometry of the kind illustrated for the augmentation element in FIGS. 14 and 15, i.e. include a body with a plurality of openings, especially in a segmented manner, i.e. comprising, as a function of the azimuthal angle, sections with openings and sections without openings. The openings in this even further embodiment may constitute a substantial portion of the surface of the element's convex hull, i.e. the empty spaces may constitute a substantial portion of for example at least 50%, at least 60% or at least ⅔ of the surface of an imaginary cylinder of which the protecting element 96 forms the non-empty portions.
(78) In all embodiments with a protecting element, (that may in some embodiments, as mentioned, serve as mask) the material of the protecting element may be a metal or a ceramic material. Because the surface of such material is repellant for liquefied thermoplastic material, the polymer will only weakly adhere to the protecting element so that the latter may be relatively easily be removed. This is even the case in configurations of the above-mentioned kind with openings through which the polymer material gets to the bone tissue—if the thickness of the protecting element is sufficiently thin, for example having a thickness of 0.1 mm or less.
(79) In all embodiments with a protecting element, the protecting element may optionally be provided with an axial slit so that after removal of the shaft it may be radially collapsed and/or peeled off for removal.
(80) The embodiments of FIG. 20 in addition may have the following optional features: the distal foot 6 that for example may protect a nerve underneath the initial opening; weakening grooves at the outside of the augmentation element 1.
(81) In addition or as an alternative to protection from friction, an outer protection element 96 as shown in FIG. 20 may also serve other purposes. Especially, it may protect from heat conducted in the elements encompassed by the protection element 96. In addition, or as an alternative, it may itself take part in the energy conduction, for example by serving as a (ground) electrode for conducting electricity for the purpose of heating from the auxiliary element through the tool 3 or directly the augmentation element.
(82) According to yet another approach, the augmentation process may be combined with measures to deflect mechanical oscillations. A first approach is schematically illustrated in FIG. 21. FIG. 21 depicts a device 101 for deflecting mechanical oscillations including an elongate and bent oscillation element 102, so that the oscillation element 101 when excited to oscillate transversally at a coupling-in point oscillates transversally at a coupling-out point. The coupling-in point includes an input terminal 103 (that may be coupled to an oscillation source), and at the coupling-out point an output terminal 104 is formed, wherein a is provided with a sleeve-like terminal 104 that may either serve as the sonotrode (or a part thereof) or that may define an interface to the sonotrode. An auxiliary element that guides the augmentation element during the process may be guided in the center of the sleeve-like terminal 104. The device 101 at the region of the output terminal 104 may also include a through opening (cannulation) through which the auxiliary element may project and be held from its proximal side. While the embodiment of FIG. 20 does not readily allow for active application of a counter-force to the applied force by which the sonotrode is pressed against the distal direction, such active counter-force may not be necessary in cases where the tissue has enough strength to provide sufficient resistance.
(83) Yet another approach is depicted in FIG. 22. FIG. 22 illustrates a deflection device 101 that has a ring-shaped resonating body. The angle between the coupling-in port and the coupling-out point is an integer fraction of 360°. The coupling-out terminal 104 may again be sleeve-like. The auxiliary element 2 may be passively guided in an interior of the sleeve-like terminal 104. It may also be held by (not shown) elements that grip the auxiliary from outside of the plane defined by the ring-shaped resonating body.
(84) A variant of the embodiment of FIG. 22 is shown in FIG. 23. In contrast to the embodiment of FIG. 22, the coupling-out terminal 104 is attached to the inside of the ring and to its proximal (upper) portion.
(85) In a variant of the embodiment of FIG. 23, the ring-shaped resonating body may be closed. The coupling-out terminal 104 may then project through a bore in the ring.
(86) A further possibility of deflecting mechanical oscillations for inputting energy to liquefy at least portions of the augmentation element is shown in FIG. 24. FIG. 24 very schematically illustrates a “rearward” configuration, i.e. a configuration in which a tensile force is coupled into the tool—namely, the sonotrode 3—while energy is coupled into the tool and from there into the augmentation element 1.
(87) In this configuration, the sonotrode has a distal broadening 92 (foot) that has a proximally facing coupling-out face that during the coupling of energy into the augmentation element 1 interfaces with a distal coupling-in face of the augmentation element 1. The sonotrode in addition has a cable 8 through that is connected to the distal broadening 92 and that connects the latter to a vibration source that in FIG. 24 is encased in the housing of a vibration generating apparatus 401. The cable 8 may, for example, be connected to a vibration generating module within the apparatus 401, which vibration generating module includes an ultrasonic transducer and is shiftable inside the housing so that during the process the cable can be pulled in the housing thereby pulling the distal broadening 92 towards the housing.
(88) For deflecting the mechanical oscillations, the arrangement includes a deflection structure that in the depicted embodiment includes a mounting protrusion 402 with a deflection wheel 403 rotatingly mounted thereto. The counter element 2 (auxiliary element) is, in the embodiment of FIG. 24, also directly mounted to the housing of the apparatus 401. For augmentation, the arrangement with the apparatus 401, sonotrode 8, 92 and the augmentation element is positioned relative to the tissue so that the distal broadening 92 and, at least partially, the augmentation element 1 are placed in the tissue opening, and then the distal broadening is retracted towards a proximal direction by pulling the cable 8 while mechanical vibrations are coupled into the latter. The deflection structure serves for deflecting the mechanical vibrations by an angle that in the depicted configuration is at least approximately defined by the structure of the apparatus 401 with the counter element 2.
(89) A configuration as illustrated in FIG. 24 may, for example, like the previously discussed concept, be advantageous for accessing tissue openings that would be difficult to access by an arrangement with movements only along a particular axis being possible, for example cavities resulting after a tooth extraction.
(90) FIG. 24 also shows the deflection angle α (in this text, the deflection angle is defined in a manner that a deflection by 180° is no deflection).
(91) In the variant of FIG. 25, the counter element 2 is not mounted to the housing of the apparatus but is a separate part. In this configuration, the operator (surgeon, dentist) needs to position two different parts (namely, the apparatus and the counter element) but can choose the deflection angle freely and can vary it during the process. The deflection unit including the deflection wheel 403 may be mounted to the housing of the apparatus (may be part of the apparatus) or may be a separate part.
(92) In embodiments where the deflection unit belongs to the apparatus, is readily possible to make the deflection unit extendible, i.e. to adjust the distance between the housing 401 and the deflecting element (the wheel 403 in the depicted configuration).
(93) As an alternative to using a wheel, also a deflection edge, for example with a cable guiding channel may be used.
(94) FIG. 26 schematically illustrates using a radiation source for coupling energy into the augmentation element 1 for the step of impinging the augmentation element with energy while the same is subject to a pressing force. To this end, the tool 3 is chosen to be a glass cylinder into which radiation is coupled from the proximal side. The auxiliary element 2 includes a foot interfacing with the distal end face of the augmentation element. The light coming in through the tool 3 may be absorbed at the distal end 301 of the tool 3, by the augmentation element (reference number 302), or at the surface 303 of the foot at the interface to the augmentation element.
(95) FIG. 27 shows an example of electricity conducted through the augmentation element 1 (which then includes an electrically conducting material with a relatively low conductivity). To this end, the tool 3 includes a first electrode 311 at the interface to the augmentation element 1 and the auxiliary element 2 includes a second electrode 312 at the interface to the augmentation element.
(96) As an alternative, the tool 3 could be provided with a resistance heater capable of heating the interface to the augmentation element. Note that this is possible both in a forward configuration with a tool 3 as shown in FIG. 27 as well as in rearward configurations with a tool having the shape of the auxiliary element 2 of FIG. 27 and with a counter element for exerting a counter force, the counter element example having the shape of the tool of FIG. 3.
(97) The configurations in FIGS. 26 and 27 may be symmetric about the axis 204 or may be formed as in examples of the hereinbefore described kind, especially in examples of segmented augmentation. The principle of radiation or electricity as energy source is further also applicable to other embodiments of the invention taught herein.
