Abstract
A system for establishing an anchorage or augmentation in hard tissue with the aid of a material having thermoplastic properties, which is brought to the site of the anchorage or reinforcement in a solid state, is liquefied in situ, and, in a liquefied state, is displaced to contact the object. The system includes a housing with a proximal housing part and mounted therein, a transmitting piece possibly coupled to an energy source and a driver spring, a distal housing part releasably coupled to the proximal housing part, a permeable sleeve couplable to the distal housing part, and a thermoplastic element positionable in the permeable sleeve. The two housing parts, the transmitting piece, the driver spring and the permeable sleeve form a closed load frame in which the thermoplastic element is compressed between the transmitting piece and the permeable sleeve.
Claims
1. A system for establishing an anchorage or a reinforcement in an object with the aid of a material having thermoplastic properties, which is brought to the site of the anchorage or reinforcement in a solid state, is liquefied in situ, and, in a liquefied state, is displaced to contact the object, the system comprising: a housing with a proximal housing part and a distal housing part, the distal housing part having a smaller cross section than the proximal housing part, a distal end of the proximal housing part tapering down to a cross section similar to the cross section of the distal housing part, and the distal housing part being releasably coupled or couplable to the proximal housing part, a transmitting piece suitable for transmitting energy coupled into the transmitting piece from an energy source, the transmitting piece having a proximal and a distal end, the proximal end being arranged in the proximal housing part to be axially moveable in a limited manner and the distal end suitable for extending through the distal housing part and for protruding from a distal end of the distal housing part, a drive being arranged to act between the proximal housing part and the proximal end of the transmitting piece to bias the proximal end of the transmitting piece away from a proximal end of the housing, a permeable sleeve couplable to the distal end of the distal housing part, and a thermoplastic element comprising the material having thermoplastic properties and being positionable in the permeable sleeve, wherein, in an assembled configuration of the system the permeable sleeve with the thermoplastic element positioned therein is coupled to the distal end of the housing, the coupling being designed for tensile load transmission, and the proximal and the distal housing parts, the transmitting piece, the drive, the permeable sleeve and the thermoplastic element form a closed load frame in which the thermoplastic element is compressed between the transmitting piece and the permeable sleeve, and wherein, for enabling use of permeable sleeves and/or thermoplastic elements or for use in a revision method, the system is equipped for adjustment of an effective axial length of the distal housing part or comprises a plurality of distal housing parts or a plurality of transmitting pieces of differing axial lengths.
2. The system according to claim 1, wherein the permeable sleeve is a cannulated screw, and wherein the distal housing part, when separated from the proximal housing part, is equipped for transmitting torque to the screw.
3. The system according to claim 2, wherein the distal housing part comprises an outer cannulated shaft and an inner cannulated shaft being arranged within the outer cannulated shaft, the two shafts being rotatable relative to each other, wherein one of the cannulated shafts is equipped for being coupled to the screw in a manner suitable for transmitting a tensile load, and an other one of the two shafts is equipped for being coupled to the screw in a manner suitable for transmitting torque.
4. The system according to claim 3, wherein the inner cannulated shaft comprises a distal end suitable for transmitting torque and a proximal end suitable for coupling to the proximal housing part and suitable for coupling to a handle for applying torque, wherein the outer cannulated shaft comprises a distal end equipped with a thread dimensioned to cooperate with a thread arranged on a proximal end of the screw and a proximal end suitable for manual rotation of the outer shaft relative to the inner shaft and wherein, when the screw is not coupled to the distal housing part, the inner and the outer shafts are axially moveable relative to each other in a limited manner.
5. The system according to claim 4, wherein the cannulated screw is a poly-axial pedicle screw with a rod receiver piece, wherein the thread comprised by the outer cannulated shaft is dimensioned to cooperate with a thread arranged on the rod receiver piece, and wherein the relative axial movability of the two cannulated shafts is dimensioned for the arrangement of the poly-axial pedicle screw and the two cannulated shafts to be axially tensioned when the two threads are treaded into each other.
6. The system according to claim 1, wherein the energy source is an ultrasonic transducer unit arranged in the proximal housing part, and the transmitting piece is a sonotrode coupled to the transducer unit.
7. The system according to claim 1, wherein the axial length of the distal housing part is incrementally adjustable.
8. The system according to claim 7, wherein adjustability of the effective axial length of the distal housing part is realized by providing a telescopic length adjustment arrangement which is lockable in a selected one of a plurality of axially distanced locking positions, the telescopic length adjustment arrangement comprising a female portion and a male portion, wherein the male portion is axially moveable in the female portion.
9. The system according to claim 8, wherein, the telescopic length adjustment arrangement is integrated in a quick release coupling provided for releasably coupling the distal housing part to the proximal housing part.
10. The system according to claim 9, wherein a depth of introduction of the male portion into the female portion and therewith one of the plurality of locking positions is pre-settable by positioning a setting ring dimensioned for not being able to enter the female portion in a selected one of a plurality of setting positions.
11. The system according to claim 10, wherein the setting ring is resilient and the setting positions are circumferential grooves provided on the male portion.
12. The system according to claim 8, wherein, for locking the male part in the female part in a selected one of the axial locking positions, a locking ring with a protrusion reaching through the female portion into a selected one of a corresponding opening in the male portion is provided.
13. The system according to claim 1 and further comprising a nut or a gripper with an inner thread adapted to an outer thread provided on a portion of the transmitting piece or the energy source protruding from the proximal end of the proximal housing part.
14. The system according to claim 13, wherein the nut comprises a left and a right part, the two parts comprising cooperating pairs of pegs and openings.
15. An ultrasonic hand piece particularly suitable for implanting and augmenting a poly-axial pedicle screw in bone tissue, the hand piece comprising a proximal housing part, a distal housing part, a sonotrode coupled or couplable to a transducer unit, and a driver spring, wherein the transducer unit, a proximal portion of the sonotrode and the driver spring are arranged in the proximal housing part, wherein the distal housing part is releasably coupled or couplable to the proximal housing part, wherein an effective axial length of the distal housing part is adaptable, wherein the distal housing part comprises an inner cannulated shaft and an outer cannulated shaft, the inner cannulated shaft comprising a distal end equipped for transmitting torque and the outer cannulated shaft comprising a distal end with a thread, and wherein the two cannulated shafts are rotatable and axially moveable in a limited manner relative to each other.
16. The ultrasonic hand piece according to claim 15, and further comprising a quick release coupling with a plurality of locking positions which are axially distanced from each other, wherein a distal end of the proximal housing part constitutes a male portion of the quick release coupling and a proximal end of the inner cannulated shaft of the distal housing part constitutes a male portion of the quick release coupling.
17. A method for establishing an anchorage or reinforcement in an object with the aid of a material having thermoplastic properties, which material is brought to a site of the anchorage or reinforcement in a solid state, is liquefied in situ, and, in a liquefied state is displaced to contact the object, the method being carried out using a system according to claim 1 and comprising the steps of: adapting the system to an introduction depth by one of adjusting the effective axial length of the distal housing part, choosing from a plurality of distal housing parts having differing axial lengths one housing part, and choosing from a plurality of transmitting pieces having differing axial lengths one transmitting piece, coupling the distal housing part to the permeable sleeve and introducing the thermoplastic element into the permeable sleeve, pre-anchoring or positioning the permeable sleeve relative to the object with the aid of the distal housing part coupled to the permeable sleeve, coupling the proximal housing part to the distal housing part, liquefying and displacing material of the thermoplastic element by activating the drive and the energy source, and re-solidifying the liquefied material by deactivating the energy source, and removing part of the system from the object.
18. The method according to claim 17, wherein adapting the effective axial length of the distal housing part is carried out together with the step of coupling the distal housing part to the proximal housing part.
19. The method according to claim 18, wherein the permeable sleeve is a screw, and the step of pre-anchoring comprises rotating the screw into the object.
20. The method according to claim 17, wherein before the step of removing, the transmitting piece is eased away from the thermoplastic element by forcing the transmitting piece in a proximal direction relative to the proximal housing part.
21. The method according to claim 17, wherein, in the step of removing, the distal housing part is separated from the permeable sleeve and the permeable sleeve is left in the object.
22. The method according to claim 17, wherein the method is a medical method of minimally invasive or open surgery and the object comprises hard tissue or hard tissue replacement material in a human or animal patient.
23. The method according to claim 17, wherein the method is a non-medical method and the object comprises fibrous, porous or foam material or, at least in an area in which the anchoring or reinforcement is to be established, comprises cavities or structures suitable for being penetrated by the liquefied material having thermoplastic properties.
24. A method for revision of an anchorage established with the method according to claim 17, the method comprising the steps of: providing a transmitting piece with an axial length greater by a revision stroke than the axial length of the transmitting piece used for establishing the anchorage, assembling the system comprising coupling the distal housing part to the permeable sleeve and coupling the proximal housing part to the distal housing part, liquefying and displacing material of the thermoplastic element by activating the drive and the energy source, removing the system from the object before re-solidification of the liquefied material.
25. The method according to claim 24, wherein the revision stroke is 2 mm long.
26. The method according to claim 24, wherein, before the step of removing, the proximal housing part is de-coupled from the distal housing part and the distal housing part is used for removing the permeable sleeve.
27. The method according to claim 26, wherein the permeable sleeve is a cannulated screw and wherein, in the step of removing, the distal housing part is used to rotate the screw out of the object.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] Exemplary embodiments of the invention are described in further detail in connection with the appended Figs., wherein:
[0039] FIGS. 1A and 1B show, in a very schematic manner, a known system for establishing an anchorage or reinforcement in hard tissue with the aid of liquefaction of a material having thermoplastic properties, the system being shown in a configuration ready for the liquefaction step (FIG. 1A) and after the liquefaction step (FIG. 1B);
[0040] FIGS. 2A, 2B, and 2C illustrate the adjustment of the system according to the invention: with a first permeable sleeve and corresponding distal housing part and transmitting piece (FIG. 2A), with a second permeable sleeve and adapted distal housing part (FIG. 2B), and with a second permeable sleeve and adapted transmitting piece (FIG. 2C);
[0041] FIGS. 3A, 3B, 3C and 3D illustrate the revision method, wherein FIG. 3A shows the system used for establishing the anchoring, FIGS. 3B/C show the system with an adapted transmitting piece suitable for the revision, ready for the liquefaction (FIG. 3B) and on completion thereof (FIG. 3C), and FIG. 3D shows the system with an adapted distal housing part suitable for the revision;
[0042] FIGS. 4A and 4B illustrate the step of easing the transmitting piece away from the thermoplastic element before system separation, FIG. 4A illustrating very schematically equipment for such easing and FIG. 4B shows an example of such equipment;
[0043] FIGS. 5A, 5B and 5C illustrate a preferred embodiment of the system according to the invention, wherein the system includes a length-adjustable quick release coupling between distal and proximal housing part, and wherein the systems of FIGS. 5A and 5B are adapted to differing permeable sleeves and wherein FIG. 5C shows a detail of the distal housing part on a larger scale;
[0044] FIG. 6 is a lateral view of the distal housing part of the system according to FIGS. 5A and 5B;
[0045] FIG. 7 shows on a larger scale the length adjustable quick release coupling between distal and proximal housing part of the system as shown in FIGS. 5A and 5B;
[0046] FIG. 8 shows a further example of a length adjustment suitable for a distal housing part;
[0047] FIG. 9 is a lateral view of a distal housing part equipped as shown in FIG. 8; FIGS. 10A and 10B are cross sections through a further example of a length adjustable distal housing part in a locked configuration (FIG. 10A) and in an un-locked configuration (FIG. 10B);
[0048] FIGS. 11 and 12 shown, in a schematic manner, further exemplary embodiments of telescopic incremental length adjustment arrangements being suitable for the system according to the invention;
[0049] FIG. 13 shows a further exemplary embodiment of a length adjustable quick-release coupling suitable for application in a system according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0050] In all appended Figs., same reference numerals designate same elements or similar elements serving same functions.
[0051] FIGS. 1A and 1B illustrate, in a very schematic manner, the principle of the system according to the state of the art, of which the invention constitutes a further development. The system is shown sectioned along its longitudinal axis and in an assembled configuration. FIG. 1A shows the system ready for the liquefaction step and FIG. 1B on completion of the liquefaction step. The system includes a housing with a proximal housing part 1 and a distal housing part 2, the two housing parts 1 and 2 fixed to each other in a location A or forming an integral unity. In the proximal housing part 1, the proximal end of the transmitting piece 3 and possibly coupled thereto the energy source 4, and the driver spring 5 are arranged in a per se known and therefore not further illustrated manner. A distal portion of the transmitting piece 3 extends through the distal housing part 2 and protrudes from the distal end thereof. For rendering the system particularly suitable for minimally invasive surgery, the distal housing part 2 has preferably a smaller cross section than the proximal housing part 1, wherein the distal end of the proximal housing part 1 tapers down to a reduced cross section adapted to the smaller cross section of the distal housing part 2. The permeable sleeve 6 with the thermoplastic element 7 positioned therein is coupled to the distal end of the distal housing part 2 (location B).
[0052] The system parts are dimensioned and arranged such that, in the initial configuration as shown in FIG. 1A, the transmitting piece 3 is in a most proximal position and is preferably locked in this position and the distal face of the transmitting piece 3 has substantially the same axial position C as the proximal face of the thermoplastic element 7. For the liquefaction step, the transmitting piece 3 is unlocked to be pressed against the thermoplastic element 7 by the driver spring 5 and to be moved in distal direction to compensate loss of axial length of the thermoplastic element 7 due to the dislocation of the liquefied material (dislocated material designated 7.1 in FIG. 1B). This movement is limited with the aid of a stop, constituted e.g., by the cross section reduction of the proximal housing part 2, as shown in FIG. 1B. The stop is preferably arranged such that when the transmitting piece 3 reaches the end of its stroke, its distal end is still distanced from the bottom of the central opening of the permeable sleeve 6 (axial position D) such that a rest of the thermoplastic element 7 remains in the permeable sleeve 6 and contact between the transmitting piece 3 and the permeable sleeve 6 is prevented. The stroke of the transmitting piece may be manually shortened by deactivation of the energy source or the system may be equipped with an axially displaceable stop for presetting a desired length of the stroke of the transmitting piece.
[0053] FIGS. 2A-2C illustrate the principle of the system according to the invention which is equipped for accommodating permeable sleeves and/or thermoplastic elements of differing axial lengths without change to its functioning. As in FIGS. 1A-1B, the system is shown axially sectioned and in an initial configuration, i.e. ready for the liquefaction step. FIG. 2A shows the assembled system, wherein the permeable sleeve 6.1 has a first effective axial length, the distal housing part 2 has an effective axial length LH.1 (distance between axial positions A and B), the thermoplastic element 7 has an axial length such that the distal end of the transmitting piece 3.1 has to reach into the permeable sleeve 6.1 by a depth LI.1 (distance between axial positions B and C) for being in contact with the thermoplastic element 7. FIGS. 2B and 2C show the system with a permeable sleeve 6.2 having a second, greater axial length and with a same thermoplastic element 7. This results in a greater depth LI.2, which is compensated by a correspondingly adapted smaller axial length LH.2 of the distal housing part 2 (FIG. 2B) or by a correspondingly longer transmitting piece 3.2 (FIG. 2C). Generally speaking, the axial length of the distal housing part 2 or of the transmitting piece 3 is adapted to the depth LI (distance between axial positions B and C) by which the transmitting piece 3 needs to initially reach into the permeable sleeve 6 to contact the proximal face of the thermoplastic element 7.
[0054] FIGS. 2A-2C show clearly, that the illustrated system adjustment to differing axial lengths of permeable sleeve 6 and/or thermoplastic element 7 does in no way interfere with the arrangement of proximal housing part 1, transmitting piece 3 and driver spring 5 and therefore does not interfere with the functioning of the system.
[0055] The inventive system adjustment as illustrated by FIGS. 2A-2C is realized by a corresponding adjustment of the effective distal length of the distal housing part 2 or by providing a plurality of distal housing parts 2 or transmitting pieces 3 of differing axial lengths and by mounting a selected one of the plurality in the system. If the system works with vibrational energy and the transmitting piece is designed to vibrate with maximum amplitude at its distal end, adaptation of the axial length of the distal housing part is preferred in particular for larger differences to be compensated, because only small such compensations can be realized with transmitting pieces with only differing axial length, i.e., without adaptation of their vibration characteristics also.
[0056] FIGS. 3A-3D illustrate the method of revision using the system as already described in connection with FIGS. 1A-B and 2A-2C. FIG. 3A shows the system on completion of the liquefaction step being part of the anchoring or reinforcing procedure in which the anchorage to be revised is produced. FIG. 3A shows the system according to FIG. 2A in a configuration as illustrated in FIG. 1B, i.e., the transmitting piece 3.1 has reached the end of its stroke and is stopped with its distal end at axial position D, a rest 7.2 of the thermoplastic element 7 remaining in the permeable sleeve 6.1. FIG. 3B shows the assembled system ready for the liquefaction step of the revision method, for which only a small stroke (revision stroke) of the transmitting piece, e.g., of 2 mm, is needed. For enabling this small stroke, the system comprises, compared with the system according to FIG. 3A, a slightly longer (e.g., longer by 2 mm) transmitting piece 3.3 enabling the small stroke necessary for the revision, without the transmitting piece 3.3 to be brought into its initial position. FIG. 3C shows the system after the liquefaction step, in which again the transmitting piece 3.3 is stopped in its final position and its distal end has reached axial position D.1 preferably still being distanced from the bottom of the central opening of the permeable sleeve.
[0057] FIG. 3D illustrates the fact that the same as is achievable with the slightly longer transmission piece 3.3 as illustrated in FIGS. 3B-3C can be achieved with a slightly shorter distal housing part 2.3. This means that for being applicable for the revision method, the system is equipped with the same adjustability (adaptable axial length of distal housing part or plurality of distal housing parts or transmitting pieces of differing axial lengths) as above described for its adjustability for permeable sleeves and or thermoplastic elements, wherein because of the small size of the stroke of the transmitting piece necessary for the revision, the embodiment with the plurality of transmitting pieces may be preferred. If a revision specific distal housing part with a slightly shortened axial length is provided and if the permeable sleeve is a cannulated screw, it is advantageous to equip the proximal end of this distal housing part with means for applying torque to the screw for removing it from the hard tissue, e.g., with a gnarled grip or a hand wheel (not shown).
[0058] FIG. 4A shows again in a very schematic manner, the system according to FIG. 2A which is shown in a configuration as illustrated in FIG. 1B (after the liquefaction step of the anchoring or reinforcing procedure) and which is further equipped for easing separation of the transmitting piece 3 from the thermoplastic element 7 before system separation on completion of the liquefaction and re-solidification step. Such easing is in particular necessary in cases in which the material of the thermoplastic element 7 is liquefied not only in a distal part of the element 7 but also in the vicinity of the proximal face thereof and, after re-solidification, tends to stick to the distal face of the transmitting piece 3. For easing the transmitting piece 3 away from the thermoplastic element 7, the transmitting piece is forced relative to the housing and against the force of the driver spring 5 in a proximal direction. For this purpose, forcing means are provided in either one of axial positions M, N or A. A suitable such forcing means in axial position M is e.g., a threaded nut 10 cooperating with a thread on a portion of the transmitting piece 3 or of the transducer unit 4 respectively, which nut 10 abuts against the proximal end of the housing and, on rotation, forces the transmitting piece 3 in a proximal direction relative to the housing and therewith away from the thermoplastic element 7. A suitable forcing means in an axial position N is e.g., a pivoting lever 11 acting on the transmitting piece 3 or on the transducer unit 4 respectively and reaching through an opening in the proximal housing part 1. Pushing the lever end protruding from the housing in a distal direction relative to the housing forces the transmitting piece 3 proximally. A suitable forcing means for position A acts to slightly increase the axial length of the housing, preferably by forcing the proximal housing part 1 away from the distal housing part 2, which again forces the transmitting piece 3 away from the thermoplastic element 7. Such forcing means is e.g., a pair of corresponding threads one arranged on the proximal and the other one arranged on the distal housing part.
[0059] FIG. 4B illustrates in more detail an exemplary easing means being applicable to be used in axial position M as already mentioned above. The easing means is a nut 10, preferably a wing nut with an interior thread being adapted to a cooperating thread provided on the proximal end of the transmitting piece or transducer unit respectively. For being easily mounted around this proximal end, in particular if a cable is connected thereto, the nut 10 may include separable left and right parts 10.1 and 10.2, which include cooperating pairs 10.3 of peg and opening. The two nut parts are positioned around the cable or the proximal part of transmitting piece or transducer unit while being axially distanced from each other and aligned to each other. Then, they are moved axially towards each other such that each peg is introduced into the corresponding opening and therewith the two nut parts are secured relative to each other in radial direction, rendering the nut ready for operation. In the same way applicable as the wing nut according to FIG. 4B are e.g., a two-part hand wheel with an inner thread, a gripper with gripping jaws equipped with a thread on their gripping surfaces, or a pivoting lever.
[0060] FIGS. 5A-5C and FIG. 6 show in more detail a first exemplary embodiment of the system according to the invention, which is the most preferred embodiment whose features have already been listed further above. FIGS. 5A-5B show the system in section along the longitudinal axis and in a configuration ready for the liquefaction step of the anchoring or reinforcing procedure. FIG. 5C shows on a larger scale a detail of the distal housing part and FIG. 6 is a lateral view of the distal housing part without a permeable sleeve, or poly-axial pedicle screw respectively, coupled thereto.
[0061] As best illustrated by FIGS. 5A-5B, the system includes system parts as described in connection with FIGS. 1A-3D, wherein the proximal housing part is shown only partially and the transducer unit and driver spring are not shown. FIGS. 5A and 5B differ from each other like FIGS. 2A and 2B by including permeable sleeves 6.1 and 6.2 of differing axial lengths, the differing depths LI.1 and LI.2 (distance between axial positions B and C) being compensated by adaptation of the effective axial length of the distal housing part 2 (distance between axial positions A and B). The distal housing part 2 is releasably coupled to the proximal housing part 1 with the aid of a quick release coupling 8 and the adjustability is integrated in this coupling 8, i.e., the coupling is a releasable telescopic coupling arrangement with a plurality of axial locking positions, wherein locking of the coupling in a selected one of the locking positions results in a selected effective axial length of the distal housing part 2 (distance between positions A and B). The coupling 8 and its function is described in detail further below in connection with FIG. 7.
[0062] As best illustrated by FIG. 6, the distal end of the distal housing part 2 is equipped for being coupled to the proximal end of the permeable sleeve 6, which in the illustrated system is a cannulated poly-axial pedicle screw 6.3 with a rod receiver piece 6.4 held freely rotatable and pivoting by the screw head and including an inner thread for eventually receiving a locking piece for locking a rod in the receiver piece 6.4. The distal housing part 2 is a double cannulated shaft, wherein the outer shaft 12 is rotatable and movable in an axial direction in a limited manner relative to the inner shaft 13 and includes a proximal gripping portion 14 and a distal outer thread 15 dimensioned for being coupled to the inner thread of the receiver piece 6.4. The inner shaft 13 includes a proximal portion suitable as male part 8.1 of the coupling 8. Furthermore, the inner shaft 13 is equipped like a screw driver, i.e. its distal end 16 is shaped to cooperate with the screw head for transmitting torque and a compressive force to the screw, e.g., has a polygon cross section to cooperate with a corresponding polygon opening in the screw head (push-on coupling), and its proximal end 17 is equipped for coupling e.g., a handle (nor shown) thereto, e.g., by having again a polygon cross section cooperating with a polygon-shaped opening in the handle.
[0063] FIG. 5C shows on a larger scale the connection of the inner and outer shafts 13 and 12 constituting the distal housing part 2 of the system according to FIGS. 5A-5B and 6. For the two shafts being rotatable and axially moveable relative to each other, the inner shaft 13 includes a circumferential groove 60 of an axial extension LG and the outer shaft 12 includes a locking element 61 extending into the groove 60, the locking element 61 being mounted in a through bore 62, when the inner shaft 13 is positioned in the outer shaft 12.
[0064] For coupling the poly-axial pedicle screw including the screw 6.3 and the receiver piece 6.4 to the distal housing part 2 as illustrated in FIGS. 5A/B and 6, the distal end 16 of the inner shaft 13 is pushed into the corresponding opening in the head of screw 6.3, and then the receiver piece 6.4 is positioned coaxially with the screw 6.3 and the distal housing part and the outer shaft 12 is rotated for engaging the distal thread 15 of the outer shaft 13 with the inner thread of the rod receiver piece 6.4, whereby the locking piece 61 moves in a distal direction in the groove 60. Therein the axial extension LG of groove 60 is adapted to the axial lengths of the distal ends 15 and 16 of the two shafts 12 and 13 such that LG is larger than the axial length x of the polygon end 16 of the inner shaft 13, or the depth to which this end can be introduced into the screw head respectively, and shorter than the sum of x plus the axial lengthy of the thread 15 of the outer shaft 12. This means that by threading the thread 15 into the receiver piece 6.4, the two shafts 12 and 13, the screw 6.3 and the receiver piece 6.4 can be axially tensioned together when the locking piece 61 has reached its most distal position in the groove 60, such that the assembly of poly-axial screw and double-shaft distal housing part 2 form a rigid entity in which the screw head is forced into the receiver piece and therewith is oriented as coaxially as possible with the distal housing part.
[0065] Alternative designs of the distal housing part 2 and in particular of the distal end thereof are dependent on the proximal end of the permeable sleeve 6 to be used in the system. For cooperation with a threaded permeable sleeve (screw) including a proximal end (e.g., screw head) with a threaded opening and an outer non-circular (e.g., hexagonal) shape, the distal housing part 2 may again include an inner and an outer cannulated shaft, wherein the function of the two shafts is, compared to the distal housing part as shown in FIGS. 5A-5B and 6, is reversed as described for the applicator in the above cited publication WO 2011/091545. Designing couplings between any permeable sleeve suitable for the system according to the invention and a corresponding distal housing part constitutes no problem for one skilled in the art, wherein, as detailed further above, the coupling needs to be capable of transmitting the tensile load acting on it during the liquefaction process and any compressive force necessary for positioning and possibly pre-anchoring the permeable sleeve in the hard tissue before the step of liquefaction and re-solidification, and wherein the coupling needs to be releasable when the permeable sleeve is finally positioned and anchored in the tissue, i.e., with as little force acting on the permeable sleeve as possible, and, in particular in the case of application in minimally invasive surgery, with the necessary handling restricted to the proximal end of the distal housing part 2.
[0066] FIG. 7 illustrates in further detail the functioning of the coupling 8 between the distal housing part 1 and the proximal housing part 2 as already shown in FIGS. 5A-5B, wherein this coupling is shown in section along the longitudinal axis. The coupling 8 is a quick release coupling with integrated telescopic length adaptability. FIG. 7 shows the coupling configuration in which the effective axial length of the distal housing part 2 is the smallest possible. The male part 8.1 of the coupling 8 is constituted by the proximal end of the inner shaft 13 of the distal housing part 2 and includes a plurality of circumferential grooves 22 and a resilient setting ring 23. The setting ring 23 is dimensioned for firmly sitting in a selected one of the grooves 22, for being able to be manually moved from one of the grooves 22 to another one, and for not being able to enter the distal opening of the female coupling part 8.2. This female coupling part 8.2 is constituted by the distal end of the proximal housing part 1, which, for this function, in a per se known manner, has an inner cross section adapted to the outer cross section of the male part 8.1 and is equipped with a spring loaded locking ring 26 and at least one locking ball 27 positioned in an opening in the proximal housing part 1, wherein the locking ball 27 is held in the opening by the locking ring 25 in its locking position and is protruding into the inside of the proximal housing part 1. Movement of the locking ball 27 radially outward and therewith allowing the male coupling part 8.1 to be introduced into and axially moved in the female coupling part 8.2 is possible only, when the locking ring 25 is moved axially against the action of its spring 28.
[0067] For coupling the distal housing part 2 to the proximal housing part 1 and at the same time setting the effective axial length of the distal housing part 2, the setting ring 23 is positioned in the corresponding groove 22, then, the locking ring 26 is moved against the action of its spring 28 from its locking position to its inactive position and the male coupling part 8.1 is introduced into the female coupling part 8.2 as deep as the setting ring 23 allows. Then the locking ring 26 is released to resume, driven by its spring 28, its locking position.
[0068] FIG. 8 shows in the same manner as FIG. 7 an alternative embodiment of a telescopic length adjustment arrangement, which, in this case, is not releasable and is therefore applicable in a system comprising, in addition to the telescopic length adjustment arrangement, a releasable coupling 8 between proximal and distal housing parts, which releasable coupling 8 has one locking position only. The non-releasable telescopic length adjustment arrangement connects two portions of the distal housing part or in the illustrated case two portions 13.1. and 13.2 of the inner shaft 13, wherein the two portions are designed for telescopically fitting inside each other, wherein the male portion 13.2 includes a plurality of axially spaced grooves 22 and the female portion 13.1 a through bore 29, and wherein a resilient locking clip 30 is provided, the locking clip 30 including an inner projection 31 adapted to be able to reach through the through bore 29 into a selected one of the grooves 22 which is aligned with the through bore 29, and therewith locking the male and the female portions 13.2 and 13.1 relative to each other in one of a plurality of possible locking positions. Therein, suitable provisions are preferably provided for preventing complete separation of the female and male portions.
[0069] FIG. 9 shows, in its entirety and separated from other system parts, the distal housing part 2 of the system embodiment which is partially shown in FIG. 8 and it shows in particular the above described resilient locking clip 30 of the telescopic length adjustment arrangement as discussed in connection with FIG. 8. This resilient locking clip 30 is shown in its locking position. For un-locking the telescopic length adjustment arrangement, the resilient locking clip 30 is moved radially away from the distal housing part 2 into a non-locking position in which the protrusion 31 (not visible in FIG. 9) is retrieved at least from the groove 22 to allow relative axial movement between the male and female portions 13.2 and 13.1 and is prevented from falling off the distal housing part 2 e.g., by a resilient safety strap 32.
[0070] FIGS. 10A-10B are cross sections through a telescopic length adjustment arrangement similar to the one discussed above in connection with FIGS. 8 and 9, wherein FIG. 10A shows the resilient locking clip 30 in its locking position and FIG. 10B in its non-locking position.
[0071] FIGS. 11 and 12 illustrate further exemplary telescopic length adjustment arrangements which may be designed to be releasable (applicable in a system similar to the system according to FIGS. 5A-5B, 6 and 7) or non-releasable (applicable in a system similar to the system according to FIGS. 8 and 9).
[0072] According to FIG. 11 the male or inner portion 35 of the arrangement includes at least one longitudinal groove 40 on its outer surface and a resilient wing 41 with one end fixed to the outer surface of the inner portion and an outwardly biased free end, the resilient wing 41 being forcible into a corresponding depression in the named outer surface. The female or outer portion 36 includes at least one protrusion 42 on its inner surface and a plurality of through openings 43. Therein, the groove 40 and the protrusion 42 are adapted to each other for preventing rotation of the inner portion 35 relative to the outer portion 36 and the resilient wing 41 is adapted to the through openings 43 for its free end to be positioned in one of the through openings 43 when the two are aligned to each other such locking the two portions 35 and 36 relative to each other in a selected one of a plurality of locking positions. For unlocking, the free end of the resilient wing 41 is manually pressed to the inside of the through opening 43.
[0073] According to FIG. 12, the male or inner portion 35 includes, on its outer surface, at least one longitudinal groove 40 and a plurality of axially distanced cross grooves 46 that cross the longitudinal groove 40 and have closed ends. The outer part 36 includes at least one inner protrusion 42 adapted to be moveable in the longitudinal groove 40 and in the cross grooves 46. For adjusting the axial length of the arrangement according to FIG. 12, the inner protrusion 42 being positioned in one of the cross grooves 46 is aligned with the longitudinal groove 40 by rotating the two portions 35 and 36 relative to each other such allowing relative axial movement between the two portions. For locking the arrangement, the inner protrusion 42 is aligned with a crossing of longitudinal and cross groove and the outer portion 36 is rotated relative to the inner portion 35 to move the protrusion 42 into the cross groove 46 therewith locking the arrangement.
[0074] FIG. 13 illustrates a further exemplary embodiment of a telescopic length arrangement. The inner or male portion 35 includes again a plurality of axially spaced circumferential grooves 22 which cooperate with a pair of spring loaded pivoting levers 50 having a locking end situated inside the outer portion 36 and adapted to reach into a selected one of the circumferential grooves 22, and a handle end situated outside of the outer portion 36 to be handlable by an operator. The springs 51 bias the locking ends of levers 50 towards the inner portion 35 for locking the arrangement. For un-locking the arrangement, the handle ends of the locking levers 50 are moved radially inwards to move the locking ends out of the circumferential groove 22 such allowing relative axial movement between the inner and outer portion.
[0075] In the preceding FIGS. 5A-13 a selection of exemplary telescopic length adjustment arrangements suitable for the systems according to the invention are described. Therein, all the described arrangements can be designed to be releasable, i.e., allowing complete removal of the male portion from the female portion, or non-releasable, i.e., equipped with suitable stops preventing removal of the male portion out of the female portion. There are a number of further, from other applications well known embodiments of such arrangements which one skilled in the art can adapt without difficulty to the present application.
